| 1 | /* Copyright (C) 1995,1996,1997,1998,1999,2000,2001,2002,2003,2004,2005,2006,2007,2008,2009 |
| 2 | * Free Software Foundation, Inc. |
| 3 | * |
| 4 | * This library is free software; you can redistribute it and/or |
| 5 | * modify it under the terms of the GNU Lesser General Public |
| 6 | * License as published by the Free Software Foundation; either |
| 7 | * version 2.1 of the License, or (at your option) any later version. |
| 8 | * |
| 9 | * This library is distributed in the hope that it will be useful, |
| 10 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 12 | * Lesser General Public License for more details. |
| 13 | * |
| 14 | * You should have received a copy of the GNU Lesser General Public |
| 15 | * License along with this library; if not, write to the Free Software |
| 16 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| 17 | */ |
| 18 | |
| 19 | \f |
| 20 | |
| 21 | /* SECTION: This code is compiled once. |
| 22 | */ |
| 23 | |
| 24 | #ifdef HAVE_CONFIG_H |
| 25 | # include <config.h> |
| 26 | #endif |
| 27 | |
| 28 | #include <alloca.h> |
| 29 | |
| 30 | #include "libguile/__scm.h" |
| 31 | |
| 32 | #include <assert.h> |
| 33 | #include "libguile/_scm.h" |
| 34 | #include "libguile/alist.h" |
| 35 | #include "libguile/async.h" |
| 36 | #include "libguile/continuations.h" |
| 37 | #include "libguile/debug.h" |
| 38 | #include "libguile/deprecation.h" |
| 39 | #include "libguile/dynwind.h" |
| 40 | #include "libguile/eq.h" |
| 41 | #include "libguile/feature.h" |
| 42 | #include "libguile/fluids.h" |
| 43 | #include "libguile/futures.h" |
| 44 | #include "libguile/goops.h" |
| 45 | #include "libguile/hash.h" |
| 46 | #include "libguile/hashtab.h" |
| 47 | #include "libguile/lang.h" |
| 48 | #include "libguile/list.h" |
| 49 | #include "libguile/macros.h" |
| 50 | #include "libguile/modules.h" |
| 51 | #include "libguile/objects.h" |
| 52 | #include "libguile/ports.h" |
| 53 | #include "libguile/print.h" |
| 54 | #include "libguile/procprop.h" |
| 55 | #include "libguile/root.h" |
| 56 | #include "libguile/smob.h" |
| 57 | #include "libguile/srcprop.h" |
| 58 | #include "libguile/stackchk.h" |
| 59 | #include "libguile/strings.h" |
| 60 | #include "libguile/threads.h" |
| 61 | #include "libguile/throw.h" |
| 62 | #include "libguile/validate.h" |
| 63 | #include "libguile/values.h" |
| 64 | #include "libguile/vectors.h" |
| 65 | |
| 66 | #include "libguile/eval.h" |
| 67 | #include "libguile/private-options.h" |
| 68 | |
| 69 | \f |
| 70 | |
| 71 | |
| 72 | static SCM unmemoize_exprs (SCM expr, SCM env); |
| 73 | static SCM canonicalize_define (SCM expr); |
| 74 | static SCM *scm_lookupcar1 (SCM vloc, SCM genv, int check); |
| 75 | static SCM unmemoize_builtin_macro (SCM expr, SCM env); |
| 76 | static void ceval_letrec_inits (SCM env, SCM init_forms, SCM **init_values_eol); |
| 77 | static SCM ceval (SCM x, SCM env); |
| 78 | static SCM deval (SCM x, SCM env); |
| 79 | |
| 80 | \f |
| 81 | |
| 82 | /* {Syntax Errors} |
| 83 | * |
| 84 | * This section defines the message strings for the syntax errors that can be |
| 85 | * detected during memoization and the functions and macros that shall be |
| 86 | * called by the memoizer code to signal syntax errors. */ |
| 87 | |
| 88 | |
| 89 | /* Syntax errors that can be detected during memoization: */ |
| 90 | |
| 91 | /* Circular or improper lists do not form valid scheme expressions. If a |
| 92 | * circular list or an improper list is detected in a place where a scheme |
| 93 | * expression is expected, a 'Bad expression' error is signalled. */ |
| 94 | static const char s_bad_expression[] = "Bad expression"; |
| 95 | |
| 96 | /* If a form is detected that holds a different number of expressions than are |
| 97 | * required in that context, a 'Missing or extra expression' error is |
| 98 | * signalled. */ |
| 99 | static const char s_expression[] = "Missing or extra expression in"; |
| 100 | |
| 101 | /* If a form is detected that holds less expressions than are required in that |
| 102 | * context, a 'Missing expression' error is signalled. */ |
| 103 | static const char s_missing_expression[] = "Missing expression in"; |
| 104 | |
| 105 | /* If a form is detected that holds more expressions than are allowed in that |
| 106 | * context, an 'Extra expression' error is signalled. */ |
| 107 | static const char s_extra_expression[] = "Extra expression in"; |
| 108 | |
| 109 | /* The empty combination '()' is not allowed as an expression in scheme. If |
| 110 | * it is detected in a place where an expression is expected, an 'Illegal |
| 111 | * empty combination' error is signalled. Note: If you encounter this error |
| 112 | * message, it is very likely that you intended to denote the empty list. To |
| 113 | * do so, you need to quote the empty list like (quote ()) or '(). */ |
| 114 | static const char s_empty_combination[] = "Illegal empty combination"; |
| 115 | |
| 116 | /* A body may hold an arbitrary number of internal defines, followed by a |
| 117 | * non-empty sequence of expressions. If a body with an empty sequence of |
| 118 | * expressions is detected, a 'Missing body expression' error is signalled. |
| 119 | */ |
| 120 | static const char s_missing_body_expression[] = "Missing body expression in"; |
| 121 | |
| 122 | /* A body may hold an arbitrary number of internal defines, followed by a |
| 123 | * non-empty sequence of expressions. Each the definitions and the |
| 124 | * expressions may be grouped arbitraryly with begin, but it is not allowed to |
| 125 | * mix definitions and expressions. If a define form in a body mixes |
| 126 | * definitions and expressions, a 'Mixed definitions and expressions' error is |
| 127 | * signalled. */ |
| 128 | static const char s_mixed_body_forms[] = "Mixed definitions and expressions in"; |
| 129 | /* Definitions are only allowed on the top level and at the start of a body. |
| 130 | * If a definition is detected anywhere else, a 'Bad define placement' error |
| 131 | * is signalled. */ |
| 132 | static const char s_bad_define[] = "Bad define placement"; |
| 133 | |
| 134 | /* Case or cond expressions must have at least one clause. If a case or cond |
| 135 | * expression without any clauses is detected, a 'Missing clauses' error is |
| 136 | * signalled. */ |
| 137 | static const char s_missing_clauses[] = "Missing clauses"; |
| 138 | |
| 139 | /* If there is an 'else' clause in a case or a cond statement, it must be the |
| 140 | * last clause. If after the 'else' case clause further clauses are detected, |
| 141 | * a 'Misplaced else clause' error is signalled. */ |
| 142 | static const char s_misplaced_else_clause[] = "Misplaced else clause"; |
| 143 | |
| 144 | /* If a case clause is detected that is not in the format |
| 145 | * (<label(s)> <expression1> <expression2> ...) |
| 146 | * a 'Bad case clause' error is signalled. */ |
| 147 | static const char s_bad_case_clause[] = "Bad case clause"; |
| 148 | |
| 149 | /* If a case clause is detected where the <label(s)> element is neither a |
| 150 | * proper list nor (in case of the last clause) the syntactic keyword 'else', |
| 151 | * a 'Bad case labels' error is signalled. Note: If you encounter this error |
| 152 | * for an else-clause which seems to be syntactically correct, check if 'else' |
| 153 | * is really a syntactic keyword in that context. If 'else' is bound in the |
| 154 | * local or global environment, it is not considered a syntactic keyword, but |
| 155 | * will be treated as any other variable. */ |
| 156 | static const char s_bad_case_labels[] = "Bad case labels"; |
| 157 | |
| 158 | /* In a case statement all labels have to be distinct. If in a case statement |
| 159 | * a label occurs more than once, a 'Duplicate case label' error is |
| 160 | * signalled. */ |
| 161 | static const char s_duplicate_case_label[] = "Duplicate case label"; |
| 162 | |
| 163 | /* If a cond clause is detected that is not in one of the formats |
| 164 | * (<test> <expression1> ...) or (else <expression1> <expression2> ...) |
| 165 | * a 'Bad cond clause' error is signalled. */ |
| 166 | static const char s_bad_cond_clause[] = "Bad cond clause"; |
| 167 | |
| 168 | /* If a cond clause is detected that uses the alternate '=>' form, but does |
| 169 | * not hold a recipient element for the test result, a 'Missing recipient' |
| 170 | * error is signalled. */ |
| 171 | static const char s_missing_recipient[] = "Missing recipient in"; |
| 172 | |
| 173 | /* If in a position where a variable name is required some other object is |
| 174 | * detected, a 'Bad variable' error is signalled. */ |
| 175 | static const char s_bad_variable[] = "Bad variable"; |
| 176 | |
| 177 | /* Bindings for forms like 'let' and 'do' have to be given in a proper, |
| 178 | * possibly empty list. If any other object is detected in a place where a |
| 179 | * list of bindings was required, a 'Bad bindings' error is signalled. */ |
| 180 | static const char s_bad_bindings[] = "Bad bindings"; |
| 181 | |
| 182 | /* Depending on the syntactic context, a binding has to be in the format |
| 183 | * (<variable> <expression>) or (<variable> <expression1> <expression2>). |
| 184 | * If anything else is detected in a place where a binding was expected, a |
| 185 | * 'Bad binding' error is signalled. */ |
| 186 | static const char s_bad_binding[] = "Bad binding"; |
| 187 | |
| 188 | /* Some syntactic forms don't allow variable names to appear more than once in |
| 189 | * a list of bindings. If such a situation is nevertheless detected, a |
| 190 | * 'Duplicate binding' error is signalled. */ |
| 191 | static const char s_duplicate_binding[] = "Duplicate binding"; |
| 192 | |
| 193 | /* If the exit form of a 'do' expression is not in the format |
| 194 | * (<test> <expression> ...) |
| 195 | * a 'Bad exit clause' error is signalled. */ |
| 196 | static const char s_bad_exit_clause[] = "Bad exit clause"; |
| 197 | |
| 198 | /* The formal function arguments of a lambda expression have to be either a |
| 199 | * single symbol or a non-cyclic list. For anything else a 'Bad formals' |
| 200 | * error is signalled. */ |
| 201 | static const char s_bad_formals[] = "Bad formals"; |
| 202 | |
| 203 | /* If in a lambda expression something else than a symbol is detected at a |
| 204 | * place where a formal function argument is required, a 'Bad formal' error is |
| 205 | * signalled. */ |
| 206 | static const char s_bad_formal[] = "Bad formal"; |
| 207 | |
| 208 | /* If in the arguments list of a lambda expression an argument name occurs |
| 209 | * more than once, a 'Duplicate formal' error is signalled. */ |
| 210 | static const char s_duplicate_formal[] = "Duplicate formal"; |
| 211 | |
| 212 | /* If the evaluation of an unquote-splicing expression gives something else |
| 213 | * than a proper list, a 'Non-list result for unquote-splicing' error is |
| 214 | * signalled. */ |
| 215 | static const char s_splicing[] = "Non-list result for unquote-splicing"; |
| 216 | |
| 217 | /* If something else than an exact integer is detected as the argument for |
| 218 | * @slot-ref and @slot-set!, a 'Bad slot number' error is signalled. */ |
| 219 | static const char s_bad_slot_number[] = "Bad slot number"; |
| 220 | |
| 221 | |
| 222 | /* Signal a syntax error. We distinguish between the form that caused the |
| 223 | * error and the enclosing expression. The error message will print out as |
| 224 | * shown in the following pattern. The file name and line number are only |
| 225 | * given when they can be determined from the erroneous form or from the |
| 226 | * enclosing expression. |
| 227 | * |
| 228 | * <filename>: In procedure memoization: |
| 229 | * <filename>: In file <name>, line <nr>: <error-message> in <expression>. */ |
| 230 | |
| 231 | SCM_SYMBOL (syntax_error_key, "syntax-error"); |
| 232 | |
| 233 | /* The prototype is needed to indicate that the function does not return. */ |
| 234 | static void |
| 235 | syntax_error (const char* const, const SCM, const SCM) SCM_NORETURN; |
| 236 | |
| 237 | static void |
| 238 | syntax_error (const char* const msg, const SCM form, const SCM expr) |
| 239 | { |
| 240 | SCM msg_string = scm_from_locale_string (msg); |
| 241 | SCM filename = SCM_BOOL_F; |
| 242 | SCM linenr = SCM_BOOL_F; |
| 243 | const char *format; |
| 244 | SCM args; |
| 245 | |
| 246 | if (scm_is_pair (form)) |
| 247 | { |
| 248 | filename = scm_source_property (form, scm_sym_filename); |
| 249 | linenr = scm_source_property (form, scm_sym_line); |
| 250 | } |
| 251 | |
| 252 | if (scm_is_false (filename) && scm_is_false (linenr) && scm_is_pair (expr)) |
| 253 | { |
| 254 | filename = scm_source_property (expr, scm_sym_filename); |
| 255 | linenr = scm_source_property (expr, scm_sym_line); |
| 256 | } |
| 257 | |
| 258 | if (!SCM_UNBNDP (expr)) |
| 259 | { |
| 260 | if (scm_is_true (filename)) |
| 261 | { |
| 262 | format = "In file ~S, line ~S: ~A ~S in expression ~S."; |
| 263 | args = scm_list_5 (filename, linenr, msg_string, form, expr); |
| 264 | } |
| 265 | else if (scm_is_true (linenr)) |
| 266 | { |
| 267 | format = "In line ~S: ~A ~S in expression ~S."; |
| 268 | args = scm_list_4 (linenr, msg_string, form, expr); |
| 269 | } |
| 270 | else |
| 271 | { |
| 272 | format = "~A ~S in expression ~S."; |
| 273 | args = scm_list_3 (msg_string, form, expr); |
| 274 | } |
| 275 | } |
| 276 | else |
| 277 | { |
| 278 | if (scm_is_true (filename)) |
| 279 | { |
| 280 | format = "In file ~S, line ~S: ~A ~S."; |
| 281 | args = scm_list_4 (filename, linenr, msg_string, form); |
| 282 | } |
| 283 | else if (scm_is_true (linenr)) |
| 284 | { |
| 285 | format = "In line ~S: ~A ~S."; |
| 286 | args = scm_list_3 (linenr, msg_string, form); |
| 287 | } |
| 288 | else |
| 289 | { |
| 290 | format = "~A ~S."; |
| 291 | args = scm_list_2 (msg_string, form); |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | scm_error (syntax_error_key, "memoization", format, args, SCM_BOOL_F); |
| 296 | } |
| 297 | |
| 298 | |
| 299 | /* Shortcut macros to simplify syntax error handling. */ |
| 300 | #define ASSERT_SYNTAX(cond, message, form) \ |
| 301 | { if (SCM_UNLIKELY (!(cond))) \ |
| 302 | syntax_error (message, form, SCM_UNDEFINED); } |
| 303 | #define ASSERT_SYNTAX_2(cond, message, form, expr) \ |
| 304 | { if (SCM_UNLIKELY (!(cond))) \ |
| 305 | syntax_error (message, form, expr); } |
| 306 | |
| 307 | \f |
| 308 | |
| 309 | /* {Ilocs} |
| 310 | * |
| 311 | * Ilocs are memoized references to variables in local environment frames. |
| 312 | * They are represented as three values: The relative offset of the |
| 313 | * environment frame, the number of the binding within that frame, and a |
| 314 | * boolean value indicating whether the binding is the last binding in the |
| 315 | * frame. |
| 316 | * |
| 317 | * Frame numbers have 11 bits, relative offsets have 12 bits. |
| 318 | */ |
| 319 | |
| 320 | #define SCM_ILOC00 SCM_MAKE_ITAG8(0L, scm_tc8_iloc) |
| 321 | #define SCM_IFRINC (0x00000100L) |
| 322 | #define SCM_ICDR (0x00080000L) |
| 323 | #define SCM_IDINC (0x00100000L) |
| 324 | #define SCM_IFRAME(n) ((long)((SCM_ICDR-SCM_IFRINC)>>8) \ |
| 325 | & (SCM_UNPACK (n) >> 8)) |
| 326 | #define SCM_IDIST(n) (SCM_UNPACK (n) >> 20) |
| 327 | #define SCM_ICDRP(n) (SCM_ICDR & SCM_UNPACK (n)) |
| 328 | #define SCM_IDSTMSK (-SCM_IDINC) |
| 329 | #define SCM_IFRAMEMAX ((1<<11)-1) |
| 330 | #define SCM_IDISTMAX ((1<<12)-1) |
| 331 | #define SCM_MAKE_ILOC(frame_nr, binding_nr, last_p) \ |
| 332 | SCM_PACK ( \ |
| 333 | ((frame_nr) << 8) \ |
| 334 | + ((binding_nr) << 20) \ |
| 335 | + ((last_p) ? SCM_ICDR : 0) \ |
| 336 | + scm_tc8_iloc ) |
| 337 | |
| 338 | void |
| 339 | scm_i_print_iloc (SCM iloc, SCM port) |
| 340 | { |
| 341 | scm_puts ("#@", port); |
| 342 | scm_intprint ((long) SCM_IFRAME (iloc), 10, port); |
| 343 | scm_putc (SCM_ICDRP (iloc) ? '-' : '+', port); |
| 344 | scm_intprint ((long) SCM_IDIST (iloc), 10, port); |
| 345 | } |
| 346 | |
| 347 | #if (SCM_DEBUG_DEBUGGING_SUPPORT == 1) |
| 348 | |
| 349 | SCM scm_dbg_make_iloc (SCM frame, SCM binding, SCM cdrp); |
| 350 | |
| 351 | SCM_DEFINE (scm_dbg_make_iloc, "dbg-make-iloc", 3, 0, 0, |
| 352 | (SCM frame, SCM binding, SCM cdrp), |
| 353 | "Return a new iloc with frame offset @var{frame}, binding\n" |
| 354 | "offset @var{binding} and the cdr flag @var{cdrp}.") |
| 355 | #define FUNC_NAME s_scm_dbg_make_iloc |
| 356 | { |
| 357 | return SCM_MAKE_ILOC ((scm_t_bits) scm_to_unsigned_integer (frame, 0, SCM_IFRAMEMAX), |
| 358 | (scm_t_bits) scm_to_unsigned_integer (binding, 0, SCM_IDISTMAX), |
| 359 | scm_is_true (cdrp)); |
| 360 | } |
| 361 | #undef FUNC_NAME |
| 362 | |
| 363 | SCM scm_dbg_iloc_p (SCM obj); |
| 364 | |
| 365 | SCM_DEFINE (scm_dbg_iloc_p, "dbg-iloc?", 1, 0, 0, |
| 366 | (SCM obj), |
| 367 | "Return @code{#t} if @var{obj} is an iloc.") |
| 368 | #define FUNC_NAME s_scm_dbg_iloc_p |
| 369 | { |
| 370 | return scm_from_bool (SCM_ILOCP (obj)); |
| 371 | } |
| 372 | #undef FUNC_NAME |
| 373 | |
| 374 | #endif |
| 375 | |
| 376 | \f |
| 377 | |
| 378 | /* {Evaluator byte codes (isyms)} |
| 379 | */ |
| 380 | |
| 381 | #define ISYMNUM(n) (SCM_ITAG8_DATA (n)) |
| 382 | |
| 383 | /* This table must agree with the list of SCM_IM_ constants in tags.h */ |
| 384 | static const char *const isymnames[] = |
| 385 | { |
| 386 | "#@and", |
| 387 | "#@begin", |
| 388 | "#@case", |
| 389 | "#@cond", |
| 390 | "#@do", |
| 391 | "#@if", |
| 392 | "#@lambda", |
| 393 | "#@let", |
| 394 | "#@let*", |
| 395 | "#@letrec", |
| 396 | "#@or", |
| 397 | "#@quote", |
| 398 | "#@set!", |
| 399 | "#@define", |
| 400 | "#@apply", |
| 401 | "#@call-with-current-continuation", |
| 402 | "#@dispatch", |
| 403 | "#@slot-ref", |
| 404 | "#@slot-set!", |
| 405 | "#@delay", |
| 406 | "#@future", |
| 407 | "#@call-with-values", |
| 408 | "#@else", |
| 409 | "#@arrow", |
| 410 | "#@nil-cond", |
| 411 | "#@bind" |
| 412 | }; |
| 413 | |
| 414 | void |
| 415 | scm_i_print_isym (SCM isym, SCM port) |
| 416 | { |
| 417 | const size_t isymnum = ISYMNUM (isym); |
| 418 | if (isymnum < (sizeof isymnames / sizeof (char *))) |
| 419 | scm_puts (isymnames[isymnum], port); |
| 420 | else |
| 421 | scm_ipruk ("isym", isym, port); |
| 422 | } |
| 423 | |
| 424 | \f |
| 425 | |
| 426 | /* The function lookup_symbol is used during memoization: Lookup the symbol in |
| 427 | * the environment. If there is no binding for the symbol, SCM_UNDEFINED is |
| 428 | * returned. If the symbol is a global variable, the variable object to which |
| 429 | * the symbol is bound is returned. Finally, if the symbol is a local |
| 430 | * variable the corresponding iloc object is returned. */ |
| 431 | |
| 432 | /* A helper function for lookup_symbol: Try to find the symbol in the top |
| 433 | * level environment frame. The function returns SCM_UNDEFINED if the symbol |
| 434 | * is unbound and it returns a variable object if the symbol is a global |
| 435 | * variable. */ |
| 436 | static SCM |
| 437 | lookup_global_symbol (const SCM symbol, const SCM top_level) |
| 438 | { |
| 439 | const SCM variable = scm_sym2var (symbol, top_level, SCM_BOOL_F); |
| 440 | if (scm_is_false (variable)) |
| 441 | return SCM_UNDEFINED; |
| 442 | else |
| 443 | return variable; |
| 444 | } |
| 445 | |
| 446 | static SCM |
| 447 | lookup_symbol (const SCM symbol, const SCM env) |
| 448 | { |
| 449 | SCM frame_idx; |
| 450 | unsigned int frame_nr; |
| 451 | |
| 452 | for (frame_idx = env, frame_nr = 0; |
| 453 | !scm_is_null (frame_idx); |
| 454 | frame_idx = SCM_CDR (frame_idx), ++frame_nr) |
| 455 | { |
| 456 | const SCM frame = SCM_CAR (frame_idx); |
| 457 | if (scm_is_pair (frame)) |
| 458 | { |
| 459 | /* frame holds a local environment frame */ |
| 460 | SCM symbol_idx; |
| 461 | unsigned int symbol_nr; |
| 462 | |
| 463 | for (symbol_idx = SCM_CAR (frame), symbol_nr = 0; |
| 464 | scm_is_pair (symbol_idx); |
| 465 | symbol_idx = SCM_CDR (symbol_idx), ++symbol_nr) |
| 466 | { |
| 467 | if (scm_is_eq (SCM_CAR (symbol_idx), symbol)) |
| 468 | /* found the symbol, therefore return the iloc */ |
| 469 | return SCM_MAKE_ILOC (frame_nr, symbol_nr, 0); |
| 470 | } |
| 471 | if (scm_is_eq (symbol_idx, symbol)) |
| 472 | /* found the symbol as the last element of the current frame */ |
| 473 | return SCM_MAKE_ILOC (frame_nr, symbol_nr, 1); |
| 474 | } |
| 475 | else |
| 476 | { |
| 477 | /* no more local environment frames */ |
| 478 | return lookup_global_symbol (symbol, frame); |
| 479 | } |
| 480 | } |
| 481 | |
| 482 | return lookup_global_symbol (symbol, SCM_BOOL_F); |
| 483 | } |
| 484 | |
| 485 | |
| 486 | /* Return true if the symbol is - from the point of view of a macro |
| 487 | * transformer - a literal in the sense specified in chapter "pattern |
| 488 | * language" of R5RS. In the code below, however, we don't match the |
| 489 | * definition of R5RS exactly: It returns true if the identifier has no |
| 490 | * binding or if it is a syntactic keyword. */ |
| 491 | static int |
| 492 | literal_p (const SCM symbol, const SCM env) |
| 493 | { |
| 494 | const SCM variable = lookup_symbol (symbol, env); |
| 495 | if (SCM_UNBNDP (variable)) |
| 496 | return 1; |
| 497 | if (SCM_VARIABLEP (variable) && SCM_MACROP (SCM_VARIABLE_REF (variable))) |
| 498 | return 1; |
| 499 | else |
| 500 | return 0; |
| 501 | } |
| 502 | |
| 503 | |
| 504 | /* Return true if the expression is self-quoting in the memoized code. Thus, |
| 505 | * some other objects (like e. g. vectors) are reported as self-quoting, which |
| 506 | * according to R5RS would need to be quoted. */ |
| 507 | static int |
| 508 | is_self_quoting_p (const SCM expr) |
| 509 | { |
| 510 | if (scm_is_pair (expr)) |
| 511 | return 0; |
| 512 | else if (scm_is_symbol (expr)) |
| 513 | return 0; |
| 514 | else if (scm_is_null (expr)) |
| 515 | return 0; |
| 516 | else return 1; |
| 517 | } |
| 518 | |
| 519 | |
| 520 | SCM_SYMBOL (sym_three_question_marks, "???"); |
| 521 | |
| 522 | static SCM |
| 523 | unmemoize_expression (const SCM expr, const SCM env) |
| 524 | { |
| 525 | if (SCM_ILOCP (expr)) |
| 526 | { |
| 527 | SCM frame_idx; |
| 528 | unsigned long int frame_nr; |
| 529 | SCM symbol_idx; |
| 530 | unsigned long int symbol_nr; |
| 531 | |
| 532 | for (frame_idx = env, frame_nr = SCM_IFRAME (expr); |
| 533 | frame_nr != 0; |
| 534 | frame_idx = SCM_CDR (frame_idx), --frame_nr) |
| 535 | ; |
| 536 | for (symbol_idx = SCM_CAAR (frame_idx), symbol_nr = SCM_IDIST (expr); |
| 537 | symbol_nr != 0; |
| 538 | symbol_idx = SCM_CDR (symbol_idx), --symbol_nr) |
| 539 | ; |
| 540 | return SCM_ICDRP (expr) ? symbol_idx : SCM_CAR (symbol_idx); |
| 541 | } |
| 542 | else if (SCM_VARIABLEP (expr)) |
| 543 | { |
| 544 | const SCM sym = scm_module_reverse_lookup (scm_env_module (env), expr); |
| 545 | return scm_is_true (sym) ? sym : sym_three_question_marks; |
| 546 | } |
| 547 | else if (scm_is_simple_vector (expr)) |
| 548 | { |
| 549 | return scm_list_2 (scm_sym_quote, expr); |
| 550 | } |
| 551 | else if (!scm_is_pair (expr)) |
| 552 | { |
| 553 | return expr; |
| 554 | } |
| 555 | else if (SCM_ISYMP (SCM_CAR (expr))) |
| 556 | { |
| 557 | return unmemoize_builtin_macro (expr, env); |
| 558 | } |
| 559 | else |
| 560 | { |
| 561 | return unmemoize_exprs (expr, env); |
| 562 | } |
| 563 | } |
| 564 | |
| 565 | |
| 566 | static SCM |
| 567 | unmemoize_exprs (const SCM exprs, const SCM env) |
| 568 | { |
| 569 | SCM r_result = SCM_EOL; |
| 570 | SCM expr_idx = exprs; |
| 571 | SCM um_expr; |
| 572 | |
| 573 | /* Note that due to the current lazy memoizer we may find partially memoized |
| 574 | * code during execution. In such code we have to expect improper lists of |
| 575 | * expressions: On the one hand, for such code syntax checks have not yet |
| 576 | * fully been performed, on the other hand, there may be even legal code |
| 577 | * like '(a . b) appear as an improper list of expressions as long as the |
| 578 | * quote expression is still in its unmemoized form. For this reason, the |
| 579 | * following code handles improper lists of expressions until memoization |
| 580 | * and execution have been completely separated. */ |
| 581 | for (; scm_is_pair (expr_idx); expr_idx = SCM_CDR (expr_idx)) |
| 582 | { |
| 583 | const SCM expr = SCM_CAR (expr_idx); |
| 584 | |
| 585 | /* In partially memoized code, lists of expressions that stem from a |
| 586 | * body form may start with an ISYM if the body itself has not yet been |
| 587 | * memoized. This isym is just an internal marker to indicate that the |
| 588 | * body still needs to be memoized. An isym may occur at the very |
| 589 | * beginning of the body or after one or more comment strings. It is |
| 590 | * dropped during unmemoization. */ |
| 591 | if (!SCM_ISYMP (expr)) |
| 592 | { |
| 593 | um_expr = unmemoize_expression (expr, env); |
| 594 | r_result = scm_cons (um_expr, r_result); |
| 595 | } |
| 596 | } |
| 597 | um_expr = unmemoize_expression (expr_idx, env); |
| 598 | if (!scm_is_null (r_result)) |
| 599 | { |
| 600 | const SCM result = scm_reverse_x (r_result, SCM_UNDEFINED); |
| 601 | SCM_SETCDR (r_result, um_expr); |
| 602 | return result; |
| 603 | } |
| 604 | else |
| 605 | { |
| 606 | return um_expr; |
| 607 | } |
| 608 | } |
| 609 | |
| 610 | |
| 611 | /* Rewrite the body (which is given as the list of expressions forming the |
| 612 | * body) into its internal form. The internal form of a body (<expr> ...) is |
| 613 | * just the body itself, but prefixed with an ISYM that denotes to what kind |
| 614 | * of outer construct this body belongs: (<ISYM> <expr> ...). A lambda body |
| 615 | * starts with SCM_IM_LAMBDA, for example, a body of a let starts with |
| 616 | * SCM_IM_LET, etc. |
| 617 | * |
| 618 | * It is assumed that the calling expression has already made sure that the |
| 619 | * body is a proper list. */ |
| 620 | static SCM |
| 621 | m_body (SCM op, SCM exprs) |
| 622 | { |
| 623 | /* Don't add another ISYM if one is present already. */ |
| 624 | if (SCM_ISYMP (SCM_CAR (exprs))) |
| 625 | return exprs; |
| 626 | else |
| 627 | return scm_cons (op, exprs); |
| 628 | } |
| 629 | |
| 630 | |
| 631 | /* The function m_expand_body memoizes a proper list of expressions forming a |
| 632 | * body. This function takes care of dealing with internal defines and |
| 633 | * transforming them into an equivalent letrec expression. The list of |
| 634 | * expressions is rewritten in place. */ |
| 635 | |
| 636 | /* This is a helper function for m_expand_body. If the argument expression is |
| 637 | * a symbol that denotes a syntactic keyword, the corresponding macro object |
| 638 | * is returned, in all other cases the function returns SCM_UNDEFINED. */ |
| 639 | static SCM |
| 640 | try_macro_lookup (const SCM expr, const SCM env) |
| 641 | { |
| 642 | if (scm_is_symbol (expr)) |
| 643 | { |
| 644 | const SCM variable = lookup_symbol (expr, env); |
| 645 | if (SCM_VARIABLEP (variable)) |
| 646 | { |
| 647 | const SCM value = SCM_VARIABLE_REF (variable); |
| 648 | if (SCM_MACROP (value)) |
| 649 | return value; |
| 650 | } |
| 651 | } |
| 652 | |
| 653 | return SCM_UNDEFINED; |
| 654 | } |
| 655 | |
| 656 | /* This is a helper function for m_expand_body. It expands user macros, |
| 657 | * because for the correct translation of a body we need to know whether they |
| 658 | * expand to a definition. */ |
| 659 | static SCM |
| 660 | expand_user_macros (SCM expr, const SCM env) |
| 661 | { |
| 662 | while (scm_is_pair (expr)) |
| 663 | { |
| 664 | const SCM car_expr = SCM_CAR (expr); |
| 665 | const SCM new_car = expand_user_macros (car_expr, env); |
| 666 | const SCM value = try_macro_lookup (new_car, env); |
| 667 | |
| 668 | if (SCM_MACROP (value) && SCM_MACRO_TYPE (value) == 2) |
| 669 | { |
| 670 | /* User macros transform code into code. */ |
| 671 | expr = scm_call_2 (SCM_MACRO_CODE (value), expr, env); |
| 672 | /* We need to reiterate on the transformed code. */ |
| 673 | } |
| 674 | else |
| 675 | { |
| 676 | /* No user macro: return. */ |
| 677 | SCM_SETCAR (expr, new_car); |
| 678 | return expr; |
| 679 | } |
| 680 | } |
| 681 | |
| 682 | return expr; |
| 683 | } |
| 684 | |
| 685 | /* This is a helper function for m_expand_body. It determines if a given form |
| 686 | * represents an application of a given built-in macro. The built-in macro to |
| 687 | * check for is identified by its syntactic keyword. The form is an |
| 688 | * application of the given macro if looking up the car of the form in the |
| 689 | * given environment actually returns the built-in macro. */ |
| 690 | static int |
| 691 | is_system_macro_p (const SCM syntactic_keyword, const SCM form, const SCM env) |
| 692 | { |
| 693 | if (scm_is_pair (form)) |
| 694 | { |
| 695 | const SCM car_form = SCM_CAR (form); |
| 696 | const SCM value = try_macro_lookup (car_form, env); |
| 697 | if (SCM_BUILTIN_MACRO_P (value)) |
| 698 | { |
| 699 | const SCM macro_name = scm_macro_name (value); |
| 700 | return scm_is_eq (macro_name, syntactic_keyword); |
| 701 | } |
| 702 | } |
| 703 | |
| 704 | return 0; |
| 705 | } |
| 706 | |
| 707 | static void |
| 708 | m_expand_body (const SCM forms, const SCM env) |
| 709 | { |
| 710 | /* The first body form can be skipped since it is known to be the ISYM that |
| 711 | * was prepended to the body by m_body. */ |
| 712 | SCM cdr_forms = SCM_CDR (forms); |
| 713 | SCM form_idx = cdr_forms; |
| 714 | SCM definitions = SCM_EOL; |
| 715 | SCM sequence = SCM_EOL; |
| 716 | |
| 717 | /* According to R5RS, the list of body forms consists of two parts: a number |
| 718 | * (maybe zero) of definitions, followed by a non-empty sequence of |
| 719 | * expressions. Each the definitions and the expressions may be grouped |
| 720 | * arbitrarily with begin, but it is not allowed to mix definitions and |
| 721 | * expressions. The task of the following loop therefore is to split the |
| 722 | * list of body forms into the list of definitions and the sequence of |
| 723 | * expressions. */ |
| 724 | while (!scm_is_null (form_idx)) |
| 725 | { |
| 726 | const SCM form = SCM_CAR (form_idx); |
| 727 | const SCM new_form = expand_user_macros (form, env); |
| 728 | if (is_system_macro_p (scm_sym_define, new_form, env)) |
| 729 | { |
| 730 | definitions = scm_cons (new_form, definitions); |
| 731 | form_idx = SCM_CDR (form_idx); |
| 732 | } |
| 733 | else if (is_system_macro_p (scm_sym_begin, new_form, env)) |
| 734 | { |
| 735 | /* We have encountered a group of forms. This has to be either a |
| 736 | * (possibly empty) group of (possibly further grouped) definitions, |
| 737 | * or a non-empty group of (possibly further grouped) |
| 738 | * expressions. */ |
| 739 | const SCM grouped_forms = SCM_CDR (new_form); |
| 740 | unsigned int found_definition = 0; |
| 741 | unsigned int found_expression = 0; |
| 742 | SCM grouped_form_idx = grouped_forms; |
| 743 | while (!found_expression && !scm_is_null (grouped_form_idx)) |
| 744 | { |
| 745 | const SCM inner_form = SCM_CAR (grouped_form_idx); |
| 746 | const SCM new_inner_form = expand_user_macros (inner_form, env); |
| 747 | if (is_system_macro_p (scm_sym_define, new_inner_form, env)) |
| 748 | { |
| 749 | found_definition = 1; |
| 750 | definitions = scm_cons (new_inner_form, definitions); |
| 751 | grouped_form_idx = SCM_CDR (grouped_form_idx); |
| 752 | } |
| 753 | else if (is_system_macro_p (scm_sym_begin, new_inner_form, env)) |
| 754 | { |
| 755 | const SCM inner_group = SCM_CDR (new_inner_form); |
| 756 | grouped_form_idx |
| 757 | = scm_append (scm_list_2 (inner_group, |
| 758 | SCM_CDR (grouped_form_idx))); |
| 759 | } |
| 760 | else |
| 761 | { |
| 762 | /* The group marks the start of the expressions of the body. |
| 763 | * We have to make sure that within the same group we have |
| 764 | * not encountered a definition before. */ |
| 765 | ASSERT_SYNTAX (!found_definition, s_mixed_body_forms, form); |
| 766 | found_expression = 1; |
| 767 | grouped_form_idx = SCM_EOL; |
| 768 | } |
| 769 | } |
| 770 | |
| 771 | /* We have finished processing the group. If we have not yet |
| 772 | * encountered an expression we continue processing the forms of the |
| 773 | * body to collect further definition forms. Otherwise, the group |
| 774 | * marks the start of the sequence of expressions of the body. */ |
| 775 | if (!found_expression) |
| 776 | { |
| 777 | form_idx = SCM_CDR (form_idx); |
| 778 | } |
| 779 | else |
| 780 | { |
| 781 | sequence = form_idx; |
| 782 | form_idx = SCM_EOL; |
| 783 | } |
| 784 | } |
| 785 | else |
| 786 | { |
| 787 | /* We have detected a form which is no definition. This marks the |
| 788 | * start of the sequence of expressions of the body. */ |
| 789 | sequence = form_idx; |
| 790 | form_idx = SCM_EOL; |
| 791 | } |
| 792 | } |
| 793 | |
| 794 | /* FIXME: forms does not hold information about the file location. */ |
| 795 | ASSERT_SYNTAX (scm_is_pair (sequence), s_missing_body_expression, cdr_forms); |
| 796 | |
| 797 | if (!scm_is_null (definitions)) |
| 798 | { |
| 799 | SCM definition_idx; |
| 800 | SCM letrec_tail; |
| 801 | SCM letrec_expression; |
| 802 | SCM new_letrec_expression; |
| 803 | |
| 804 | SCM bindings = SCM_EOL; |
| 805 | for (definition_idx = definitions; |
| 806 | !scm_is_null (definition_idx); |
| 807 | definition_idx = SCM_CDR (definition_idx)) |
| 808 | { |
| 809 | const SCM definition = SCM_CAR (definition_idx); |
| 810 | const SCM canonical_definition = canonicalize_define (definition); |
| 811 | const SCM binding = SCM_CDR (canonical_definition); |
| 812 | bindings = scm_cons (binding, bindings); |
| 813 | }; |
| 814 | |
| 815 | letrec_tail = scm_cons (bindings, sequence); |
| 816 | /* FIXME: forms does not hold information about the file location. */ |
| 817 | letrec_expression = scm_cons_source (forms, scm_sym_letrec, letrec_tail); |
| 818 | new_letrec_expression = scm_m_letrec (letrec_expression, env); |
| 819 | SCM_SETCAR (forms, new_letrec_expression); |
| 820 | SCM_SETCDR (forms, SCM_EOL); |
| 821 | } |
| 822 | else |
| 823 | { |
| 824 | SCM_SETCAR (forms, SCM_CAR (sequence)); |
| 825 | SCM_SETCDR (forms, SCM_CDR (sequence)); |
| 826 | } |
| 827 | } |
| 828 | |
| 829 | static SCM |
| 830 | macroexp (SCM x, SCM env) |
| 831 | { |
| 832 | SCM res, proc, orig_sym; |
| 833 | |
| 834 | /* Don't bother to produce error messages here. We get them when we |
| 835 | eventually execute the code for real. */ |
| 836 | |
| 837 | macro_tail: |
| 838 | orig_sym = SCM_CAR (x); |
| 839 | if (!scm_is_symbol (orig_sym)) |
| 840 | return x; |
| 841 | |
| 842 | { |
| 843 | SCM *proc_ptr = scm_lookupcar1 (x, env, 0); |
| 844 | if (proc_ptr == NULL) |
| 845 | { |
| 846 | /* We have lost the race. */ |
| 847 | goto macro_tail; |
| 848 | } |
| 849 | proc = *proc_ptr; |
| 850 | } |
| 851 | |
| 852 | /* Only handle memoizing macros. `Acros' and `macros' are really |
| 853 | special forms and should not be evaluated here. */ |
| 854 | |
| 855 | if (!SCM_MACROP (proc) |
| 856 | || (SCM_MACRO_TYPE (proc) != 2 && !SCM_BUILTIN_MACRO_P (proc))) |
| 857 | return x; |
| 858 | |
| 859 | SCM_SETCAR (x, orig_sym); /* Undo memoizing effect of lookupcar */ |
| 860 | res = scm_call_2 (SCM_MACRO_CODE (proc), x, env); |
| 861 | |
| 862 | if (scm_ilength (res) <= 0) |
| 863 | /* Result of expansion is not a list. */ |
| 864 | return (scm_list_2 (SCM_IM_BEGIN, res)); |
| 865 | else |
| 866 | { |
| 867 | /* njrev: Several queries here: (1) I don't see how it can be |
| 868 | correct that the SCM_SETCAR 2 lines below this comment needs |
| 869 | protection, but the SCM_SETCAR 6 lines above does not, so |
| 870 | something here is probably wrong. (2) macroexp() is now only |
| 871 | used in one place - scm_m_generalized_set_x - whereas all other |
| 872 | macro expansion happens through expand_user_macros. Therefore |
| 873 | (2.1) perhaps macroexp() could be eliminated completely now? |
| 874 | (2.2) Does expand_user_macros need any critical section |
| 875 | protection? */ |
| 876 | |
| 877 | SCM_CRITICAL_SECTION_START; |
| 878 | SCM_SETCAR (x, SCM_CAR (res)); |
| 879 | SCM_SETCDR (x, SCM_CDR (res)); |
| 880 | SCM_CRITICAL_SECTION_END; |
| 881 | |
| 882 | goto macro_tail; |
| 883 | } |
| 884 | } |
| 885 | |
| 886 | /* Start of the memoizers for the standard R5RS builtin macros. */ |
| 887 | |
| 888 | |
| 889 | SCM_SYNTAX (s_and, "and", scm_i_makbimacro, scm_m_and); |
| 890 | SCM_GLOBAL_SYMBOL (scm_sym_and, s_and); |
| 891 | |
| 892 | SCM |
| 893 | scm_m_and (SCM expr, SCM env SCM_UNUSED) |
| 894 | { |
| 895 | const SCM cdr_expr = SCM_CDR (expr); |
| 896 | const long length = scm_ilength (cdr_expr); |
| 897 | |
| 898 | ASSERT_SYNTAX (length >= 0, s_bad_expression, expr); |
| 899 | |
| 900 | if (length == 0) |
| 901 | { |
| 902 | /* Special case: (and) is replaced by #t. */ |
| 903 | return SCM_BOOL_T; |
| 904 | } |
| 905 | else |
| 906 | { |
| 907 | SCM_SETCAR (expr, SCM_IM_AND); |
| 908 | return expr; |
| 909 | } |
| 910 | } |
| 911 | |
| 912 | static SCM |
| 913 | unmemoize_and (const SCM expr, const SCM env) |
| 914 | { |
| 915 | return scm_cons (scm_sym_and, unmemoize_exprs (SCM_CDR (expr), env)); |
| 916 | } |
| 917 | |
| 918 | |
| 919 | SCM_SYNTAX (s_begin, "begin", scm_i_makbimacro, scm_m_begin); |
| 920 | SCM_GLOBAL_SYMBOL (scm_sym_begin, s_begin); |
| 921 | |
| 922 | SCM |
| 923 | scm_m_begin (SCM expr, SCM env SCM_UNUSED) |
| 924 | { |
| 925 | const SCM cdr_expr = SCM_CDR (expr); |
| 926 | /* Dirk:FIXME:: An empty begin clause is not generally allowed by R5RS. |
| 927 | * That means, there should be a distinction between uses of begin where an |
| 928 | * empty clause is OK and where it is not. */ |
| 929 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 930 | |
| 931 | SCM_SETCAR (expr, SCM_IM_BEGIN); |
| 932 | return expr; |
| 933 | } |
| 934 | |
| 935 | static SCM |
| 936 | unmemoize_begin (const SCM expr, const SCM env) |
| 937 | { |
| 938 | return scm_cons (scm_sym_begin, unmemoize_exprs (SCM_CDR (expr), env)); |
| 939 | } |
| 940 | |
| 941 | |
| 942 | SCM_SYNTAX (s_case, "case", scm_i_makbimacro, scm_m_case); |
| 943 | SCM_GLOBAL_SYMBOL (scm_sym_case, s_case); |
| 944 | SCM_GLOBAL_SYMBOL (scm_sym_else, "else"); |
| 945 | |
| 946 | SCM |
| 947 | scm_m_case (SCM expr, SCM env) |
| 948 | { |
| 949 | SCM clauses; |
| 950 | SCM all_labels = SCM_EOL; |
| 951 | |
| 952 | /* Check, whether 'else is a literal, i. e. not bound to a value. */ |
| 953 | const int else_literal_p = literal_p (scm_sym_else, env); |
| 954 | |
| 955 | const SCM cdr_expr = SCM_CDR (expr); |
| 956 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 957 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 2, s_missing_clauses, expr); |
| 958 | |
| 959 | clauses = SCM_CDR (cdr_expr); |
| 960 | while (!scm_is_null (clauses)) |
| 961 | { |
| 962 | SCM labels; |
| 963 | |
| 964 | const SCM clause = SCM_CAR (clauses); |
| 965 | ASSERT_SYNTAX_2 (scm_ilength (clause) >= 2, |
| 966 | s_bad_case_clause, clause, expr); |
| 967 | |
| 968 | labels = SCM_CAR (clause); |
| 969 | if (scm_is_pair (labels)) |
| 970 | { |
| 971 | ASSERT_SYNTAX_2 (scm_ilength (labels) >= 0, |
| 972 | s_bad_case_labels, labels, expr); |
| 973 | all_labels = scm_append (scm_list_2 (labels, all_labels)); |
| 974 | } |
| 975 | else if (scm_is_null (labels)) |
| 976 | { |
| 977 | /* The list of labels is empty. According to R5RS this is allowed. |
| 978 | * It means that the sequence of expressions will never be executed. |
| 979 | * Therefore, as an optimization, we could remove the whole |
| 980 | * clause. */ |
| 981 | } |
| 982 | else |
| 983 | { |
| 984 | ASSERT_SYNTAX_2 (scm_is_eq (labels, scm_sym_else) && else_literal_p, |
| 985 | s_bad_case_labels, labels, expr); |
| 986 | ASSERT_SYNTAX_2 (scm_is_null (SCM_CDR (clauses)), |
| 987 | s_misplaced_else_clause, clause, expr); |
| 988 | } |
| 989 | |
| 990 | /* build the new clause */ |
| 991 | if (scm_is_eq (labels, scm_sym_else)) |
| 992 | SCM_SETCAR (clause, SCM_IM_ELSE); |
| 993 | |
| 994 | clauses = SCM_CDR (clauses); |
| 995 | } |
| 996 | |
| 997 | /* Check whether all case labels are distinct. */ |
| 998 | for (; !scm_is_null (all_labels); all_labels = SCM_CDR (all_labels)) |
| 999 | { |
| 1000 | const SCM label = SCM_CAR (all_labels); |
| 1001 | ASSERT_SYNTAX_2 (scm_is_false (scm_c_memq (label, SCM_CDR (all_labels))), |
| 1002 | s_duplicate_case_label, label, expr); |
| 1003 | } |
| 1004 | |
| 1005 | SCM_SETCAR (expr, SCM_IM_CASE); |
| 1006 | return expr; |
| 1007 | } |
| 1008 | |
| 1009 | static SCM |
| 1010 | unmemoize_case (const SCM expr, const SCM env) |
| 1011 | { |
| 1012 | const SCM um_key_expr = unmemoize_expression (SCM_CADR (expr), env); |
| 1013 | SCM um_clauses = SCM_EOL; |
| 1014 | SCM clause_idx; |
| 1015 | |
| 1016 | for (clause_idx = SCM_CDDR (expr); |
| 1017 | !scm_is_null (clause_idx); |
| 1018 | clause_idx = SCM_CDR (clause_idx)) |
| 1019 | { |
| 1020 | const SCM clause = SCM_CAR (clause_idx); |
| 1021 | const SCM labels = SCM_CAR (clause); |
| 1022 | const SCM exprs = SCM_CDR (clause); |
| 1023 | |
| 1024 | const SCM um_exprs = unmemoize_exprs (exprs, env); |
| 1025 | const SCM um_labels = (scm_is_eq (labels, SCM_IM_ELSE)) |
| 1026 | ? scm_sym_else |
| 1027 | : scm_i_finite_list_copy (labels); |
| 1028 | const SCM um_clause = scm_cons (um_labels, um_exprs); |
| 1029 | |
| 1030 | um_clauses = scm_cons (um_clause, um_clauses); |
| 1031 | } |
| 1032 | um_clauses = scm_reverse_x (um_clauses, SCM_UNDEFINED); |
| 1033 | |
| 1034 | return scm_cons2 (scm_sym_case, um_key_expr, um_clauses); |
| 1035 | } |
| 1036 | |
| 1037 | |
| 1038 | SCM_SYNTAX (s_cond, "cond", scm_i_makbimacro, scm_m_cond); |
| 1039 | SCM_GLOBAL_SYMBOL (scm_sym_cond, s_cond); |
| 1040 | SCM_GLOBAL_SYMBOL (scm_sym_arrow, "=>"); |
| 1041 | |
| 1042 | SCM |
| 1043 | scm_m_cond (SCM expr, SCM env) |
| 1044 | { |
| 1045 | /* Check, whether 'else or '=> is a literal, i. e. not bound to a value. */ |
| 1046 | const int else_literal_p = literal_p (scm_sym_else, env); |
| 1047 | const int arrow_literal_p = literal_p (scm_sym_arrow, env); |
| 1048 | |
| 1049 | const SCM clauses = SCM_CDR (expr); |
| 1050 | SCM clause_idx; |
| 1051 | |
| 1052 | ASSERT_SYNTAX (scm_ilength (clauses) >= 0, s_bad_expression, expr); |
| 1053 | ASSERT_SYNTAX (scm_ilength (clauses) >= 1, s_missing_clauses, expr); |
| 1054 | |
| 1055 | for (clause_idx = clauses; |
| 1056 | !scm_is_null (clause_idx); |
| 1057 | clause_idx = SCM_CDR (clause_idx)) |
| 1058 | { |
| 1059 | SCM test; |
| 1060 | |
| 1061 | const SCM clause = SCM_CAR (clause_idx); |
| 1062 | const long length = scm_ilength (clause); |
| 1063 | ASSERT_SYNTAX_2 (length >= 1, s_bad_cond_clause, clause, expr); |
| 1064 | |
| 1065 | test = SCM_CAR (clause); |
| 1066 | if (scm_is_eq (test, scm_sym_else) && else_literal_p) |
| 1067 | { |
| 1068 | const int last_clause_p = scm_is_null (SCM_CDR (clause_idx)); |
| 1069 | ASSERT_SYNTAX_2 (length >= 2, |
| 1070 | s_bad_cond_clause, clause, expr); |
| 1071 | ASSERT_SYNTAX_2 (last_clause_p, |
| 1072 | s_misplaced_else_clause, clause, expr); |
| 1073 | SCM_SETCAR (clause, SCM_IM_ELSE); |
| 1074 | } |
| 1075 | else if (length >= 2 |
| 1076 | && scm_is_eq (SCM_CADR (clause), scm_sym_arrow) |
| 1077 | && arrow_literal_p) |
| 1078 | { |
| 1079 | ASSERT_SYNTAX_2 (length > 2, s_missing_recipient, clause, expr); |
| 1080 | ASSERT_SYNTAX_2 (length == 3, s_extra_expression, clause, expr); |
| 1081 | SCM_SETCAR (SCM_CDR (clause), SCM_IM_ARROW); |
| 1082 | } |
| 1083 | /* SRFI 61 extended cond */ |
| 1084 | else if (length >= 3 |
| 1085 | && scm_is_eq (SCM_CADDR (clause), scm_sym_arrow) |
| 1086 | && arrow_literal_p) |
| 1087 | { |
| 1088 | ASSERT_SYNTAX_2 (length > 3, s_missing_recipient, clause, expr); |
| 1089 | ASSERT_SYNTAX_2 (length == 4, s_extra_expression, clause, expr); |
| 1090 | SCM_SETCAR (SCM_CDDR (clause), SCM_IM_ARROW); |
| 1091 | } |
| 1092 | } |
| 1093 | |
| 1094 | SCM_SETCAR (expr, SCM_IM_COND); |
| 1095 | return expr; |
| 1096 | } |
| 1097 | |
| 1098 | static SCM |
| 1099 | unmemoize_cond (const SCM expr, const SCM env) |
| 1100 | { |
| 1101 | SCM um_clauses = SCM_EOL; |
| 1102 | SCM clause_idx; |
| 1103 | |
| 1104 | for (clause_idx = SCM_CDR (expr); |
| 1105 | !scm_is_null (clause_idx); |
| 1106 | clause_idx = SCM_CDR (clause_idx)) |
| 1107 | { |
| 1108 | const SCM clause = SCM_CAR (clause_idx); |
| 1109 | const SCM sequence = SCM_CDR (clause); |
| 1110 | const SCM test = SCM_CAR (clause); |
| 1111 | SCM um_test; |
| 1112 | SCM um_sequence; |
| 1113 | SCM um_clause; |
| 1114 | |
| 1115 | if (scm_is_eq (test, SCM_IM_ELSE)) |
| 1116 | um_test = scm_sym_else; |
| 1117 | else |
| 1118 | um_test = unmemoize_expression (test, env); |
| 1119 | |
| 1120 | if (!scm_is_null (sequence) && scm_is_eq (SCM_CAR (sequence), |
| 1121 | SCM_IM_ARROW)) |
| 1122 | { |
| 1123 | const SCM target = SCM_CADR (sequence); |
| 1124 | const SCM um_target = unmemoize_expression (target, env); |
| 1125 | um_sequence = scm_list_2 (scm_sym_arrow, um_target); |
| 1126 | } |
| 1127 | else |
| 1128 | { |
| 1129 | um_sequence = unmemoize_exprs (sequence, env); |
| 1130 | } |
| 1131 | |
| 1132 | um_clause = scm_cons (um_test, um_sequence); |
| 1133 | um_clauses = scm_cons (um_clause, um_clauses); |
| 1134 | } |
| 1135 | um_clauses = scm_reverse_x (um_clauses, SCM_UNDEFINED); |
| 1136 | |
| 1137 | return scm_cons (scm_sym_cond, um_clauses); |
| 1138 | } |
| 1139 | |
| 1140 | |
| 1141 | SCM_SYNTAX (s_define, "define", scm_i_makbimacro, scm_m_define); |
| 1142 | SCM_GLOBAL_SYMBOL (scm_sym_define, s_define); |
| 1143 | |
| 1144 | /* Guile provides an extension to R5RS' define syntax to represent function |
| 1145 | * currying in a compact way. With this extension, it is allowed to write |
| 1146 | * (define <nested-variable> <body>), where <nested-variable> has of one of |
| 1147 | * the forms (<nested-variable> <formals>), (<nested-variable> . <formal>), |
| 1148 | * (<variable> <formals>) or (<variable> . <formal>). As in R5RS, <formals> |
| 1149 | * should be either a sequence of zero or more variables, or a sequence of one |
| 1150 | * or more variables followed by a space-delimited period and another |
| 1151 | * variable. Each level of argument nesting wraps the <body> within another |
| 1152 | * lambda expression. For example, the following forms are allowed, each one |
| 1153 | * followed by an equivalent, more explicit implementation. |
| 1154 | * Example 1: |
| 1155 | * (define ((a b . c) . d) <body>) is equivalent to |
| 1156 | * (define a (lambda (b . c) (lambda d <body>))) |
| 1157 | * Example 2: |
| 1158 | * (define (((a) b) c . d) <body>) is equivalent to |
| 1159 | * (define a (lambda () (lambda (b) (lambda (c . d) <body>)))) |
| 1160 | */ |
| 1161 | /* Dirk:FIXME:: We should provide an implementation for 'define' in the R5RS |
| 1162 | * module that does not implement this extension. */ |
| 1163 | static SCM |
| 1164 | canonicalize_define (const SCM expr) |
| 1165 | { |
| 1166 | SCM body; |
| 1167 | SCM variable; |
| 1168 | |
| 1169 | const SCM cdr_expr = SCM_CDR (expr); |
| 1170 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1171 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 2, s_missing_expression, expr); |
| 1172 | |
| 1173 | body = SCM_CDR (cdr_expr); |
| 1174 | variable = SCM_CAR (cdr_expr); |
| 1175 | while (scm_is_pair (variable)) |
| 1176 | { |
| 1177 | /* This while loop realizes function currying by variable nesting. |
| 1178 | * Variable is known to be a nested-variable. In every iteration of the |
| 1179 | * loop another level of lambda expression is created, starting with the |
| 1180 | * innermost one. Note that we don't check for duplicate formals here: |
| 1181 | * This will be done by the memoizer of the lambda expression. */ |
| 1182 | const SCM formals = SCM_CDR (variable); |
| 1183 | const SCM tail = scm_cons (formals, body); |
| 1184 | |
| 1185 | /* Add source properties to each new lambda expression: */ |
| 1186 | const SCM lambda = scm_cons_source (variable, scm_sym_lambda, tail); |
| 1187 | |
| 1188 | body = scm_list_1 (lambda); |
| 1189 | variable = SCM_CAR (variable); |
| 1190 | } |
| 1191 | ASSERT_SYNTAX_2 (scm_is_symbol (variable), s_bad_variable, variable, expr); |
| 1192 | ASSERT_SYNTAX (scm_ilength (body) == 1, s_expression, expr); |
| 1193 | |
| 1194 | SCM_SETCAR (cdr_expr, variable); |
| 1195 | SCM_SETCDR (cdr_expr, body); |
| 1196 | return expr; |
| 1197 | } |
| 1198 | |
| 1199 | /* According to Section 5.2.1 of R5RS we first have to make sure that the |
| 1200 | variable is bound, and then perform the `(set! variable expression)' |
| 1201 | operation. However, EXPRESSION _can_ be evaluated before VARIABLE is |
| 1202 | bound. This means that EXPRESSION won't necessarily be able to assign |
| 1203 | values to VARIABLE as in `(define foo (begin (set! foo 1) (+ foo 1)))'. */ |
| 1204 | SCM |
| 1205 | scm_m_define (SCM expr, SCM env) |
| 1206 | { |
| 1207 | ASSERT_SYNTAX (SCM_TOP_LEVEL (env), s_bad_define, expr); |
| 1208 | |
| 1209 | { |
| 1210 | const SCM canonical_definition = canonicalize_define (expr); |
| 1211 | const SCM cdr_canonical_definition = SCM_CDR (canonical_definition); |
| 1212 | const SCM variable = SCM_CAR (cdr_canonical_definition); |
| 1213 | const SCM value = scm_eval_car (SCM_CDR (cdr_canonical_definition), env); |
| 1214 | const SCM location |
| 1215 | = scm_sym2var (variable, scm_env_top_level (env), SCM_BOOL_T); |
| 1216 | |
| 1217 | if (SCM_REC_PROCNAMES_P) |
| 1218 | { |
| 1219 | SCM tmp = value; |
| 1220 | while (SCM_MACROP (tmp)) |
| 1221 | tmp = SCM_MACRO_CODE (tmp); |
| 1222 | if (scm_is_true (scm_procedure_p (tmp)) |
| 1223 | /* Only the first definition determines the name. */ |
| 1224 | && scm_is_false (scm_procedure_property (tmp, scm_sym_name))) |
| 1225 | scm_set_procedure_property_x (tmp, scm_sym_name, variable); |
| 1226 | } |
| 1227 | |
| 1228 | SCM_VARIABLE_SET (location, value); |
| 1229 | |
| 1230 | return SCM_UNSPECIFIED; |
| 1231 | } |
| 1232 | } |
| 1233 | |
| 1234 | |
| 1235 | /* This is a helper function for forms (<keyword> <expression>) that are |
| 1236 | * transformed into (#@<keyword> '() <memoized_expression>) in order to allow |
| 1237 | * for easy creation of a thunk (i. e. a closure without arguments) using the |
| 1238 | * ('() <memoized_expression>) tail of the memoized form. */ |
| 1239 | static SCM |
| 1240 | memoize_as_thunk_prototype (const SCM expr, const SCM env SCM_UNUSED) |
| 1241 | { |
| 1242 | const SCM cdr_expr = SCM_CDR (expr); |
| 1243 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1244 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 1, s_expression, expr); |
| 1245 | |
| 1246 | SCM_SETCDR (expr, scm_cons (SCM_EOL, cdr_expr)); |
| 1247 | |
| 1248 | return expr; |
| 1249 | } |
| 1250 | |
| 1251 | |
| 1252 | SCM_SYNTAX (s_delay, "delay", scm_i_makbimacro, scm_m_delay); |
| 1253 | SCM_GLOBAL_SYMBOL (scm_sym_delay, s_delay); |
| 1254 | |
| 1255 | /* Promises are implemented as closures with an empty parameter list. Thus, |
| 1256 | * (delay <expression>) is transformed into (#@delay '() <expression>), where |
| 1257 | * the empty list represents the empty parameter list. This representation |
| 1258 | * allows for easy creation of the closure during evaluation. */ |
| 1259 | SCM |
| 1260 | scm_m_delay (SCM expr, SCM env) |
| 1261 | { |
| 1262 | const SCM new_expr = memoize_as_thunk_prototype (expr, env); |
| 1263 | SCM_SETCAR (new_expr, SCM_IM_DELAY); |
| 1264 | return new_expr; |
| 1265 | } |
| 1266 | |
| 1267 | static SCM |
| 1268 | unmemoize_delay (const SCM expr, const SCM env) |
| 1269 | { |
| 1270 | const SCM thunk_expr = SCM_CADDR (expr); |
| 1271 | /* A promise is implemented as a closure, and when applying a |
| 1272 | closure the evaluator adds a new frame to the environment - even |
| 1273 | though, in the case of a promise, the added frame is always |
| 1274 | empty. We need to extend the environment here in the same way, |
| 1275 | so that any ILOCs in thunk_expr can be unmemoized correctly. */ |
| 1276 | const SCM new_env = SCM_EXTEND_ENV (SCM_EOL, SCM_EOL, env); |
| 1277 | return scm_list_2 (scm_sym_delay, unmemoize_expression (thunk_expr, new_env)); |
| 1278 | } |
| 1279 | |
| 1280 | |
| 1281 | SCM_SYNTAX(s_do, "do", scm_i_makbimacro, scm_m_do); |
| 1282 | SCM_GLOBAL_SYMBOL(scm_sym_do, s_do); |
| 1283 | |
| 1284 | /* DO gets the most radically altered syntax. The order of the vars is |
| 1285 | * reversed here. During the evaluation this allows for simple consing of the |
| 1286 | * results of the inits and steps: |
| 1287 | |
| 1288 | (do ((<var1> <init1> <step1>) |
| 1289 | (<var2> <init2>) |
| 1290 | ... ) |
| 1291 | (<test> <return>) |
| 1292 | <body>) |
| 1293 | |
| 1294 | ;; becomes |
| 1295 | |
| 1296 | (#@do (<init1> <init2> ... <initn>) |
| 1297 | (varn ... var2 var1) |
| 1298 | (<test> <return>) |
| 1299 | (<body>) |
| 1300 | <step1> <step2> ... <stepn>) ;; missing steps replaced by var |
| 1301 | */ |
| 1302 | SCM |
| 1303 | scm_m_do (SCM expr, SCM env SCM_UNUSED) |
| 1304 | { |
| 1305 | SCM variables = SCM_EOL; |
| 1306 | SCM init_forms = SCM_EOL; |
| 1307 | SCM step_forms = SCM_EOL; |
| 1308 | SCM binding_idx; |
| 1309 | SCM cddr_expr; |
| 1310 | SCM exit_clause; |
| 1311 | SCM commands; |
| 1312 | SCM tail; |
| 1313 | |
| 1314 | const SCM cdr_expr = SCM_CDR (expr); |
| 1315 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1316 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 2, s_missing_expression, expr); |
| 1317 | |
| 1318 | /* Collect variables, init and step forms. */ |
| 1319 | binding_idx = SCM_CAR (cdr_expr); |
| 1320 | ASSERT_SYNTAX_2 (scm_ilength (binding_idx) >= 0, |
| 1321 | s_bad_bindings, binding_idx, expr); |
| 1322 | for (; !scm_is_null (binding_idx); binding_idx = SCM_CDR (binding_idx)) |
| 1323 | { |
| 1324 | const SCM binding = SCM_CAR (binding_idx); |
| 1325 | const long length = scm_ilength (binding); |
| 1326 | ASSERT_SYNTAX_2 (length == 2 || length == 3, |
| 1327 | s_bad_binding, binding, expr); |
| 1328 | |
| 1329 | { |
| 1330 | const SCM name = SCM_CAR (binding); |
| 1331 | const SCM init = SCM_CADR (binding); |
| 1332 | const SCM step = (length == 2) ? name : SCM_CADDR (binding); |
| 1333 | ASSERT_SYNTAX_2 (scm_is_symbol (name), s_bad_variable, name, expr); |
| 1334 | ASSERT_SYNTAX_2 (scm_is_false (scm_c_memq (name, variables)), |
| 1335 | s_duplicate_binding, name, expr); |
| 1336 | |
| 1337 | variables = scm_cons (name, variables); |
| 1338 | init_forms = scm_cons (init, init_forms); |
| 1339 | step_forms = scm_cons (step, step_forms); |
| 1340 | } |
| 1341 | } |
| 1342 | init_forms = scm_reverse_x (init_forms, SCM_UNDEFINED); |
| 1343 | step_forms = scm_reverse_x (step_forms, SCM_UNDEFINED); |
| 1344 | |
| 1345 | /* Memoize the test form and the exit sequence. */ |
| 1346 | cddr_expr = SCM_CDR (cdr_expr); |
| 1347 | exit_clause = SCM_CAR (cddr_expr); |
| 1348 | ASSERT_SYNTAX_2 (scm_ilength (exit_clause) >= 1, |
| 1349 | s_bad_exit_clause, exit_clause, expr); |
| 1350 | |
| 1351 | commands = SCM_CDR (cddr_expr); |
| 1352 | tail = scm_cons2 (exit_clause, commands, step_forms); |
| 1353 | tail = scm_cons2 (init_forms, variables, tail); |
| 1354 | SCM_SETCAR (expr, SCM_IM_DO); |
| 1355 | SCM_SETCDR (expr, tail); |
| 1356 | return expr; |
| 1357 | } |
| 1358 | |
| 1359 | static SCM |
| 1360 | unmemoize_do (const SCM expr, const SCM env) |
| 1361 | { |
| 1362 | const SCM cdr_expr = SCM_CDR (expr); |
| 1363 | const SCM cddr_expr = SCM_CDR (cdr_expr); |
| 1364 | const SCM rnames = SCM_CAR (cddr_expr); |
| 1365 | const SCM extended_env = SCM_EXTEND_ENV (rnames, SCM_EOL, env); |
| 1366 | const SCM cdddr_expr = SCM_CDR (cddr_expr); |
| 1367 | const SCM exit_sequence = SCM_CAR (cdddr_expr); |
| 1368 | const SCM um_exit_sequence = unmemoize_exprs (exit_sequence, extended_env); |
| 1369 | const SCM cddddr_expr = SCM_CDR (cdddr_expr); |
| 1370 | const SCM um_body = unmemoize_exprs (SCM_CAR (cddddr_expr), extended_env); |
| 1371 | |
| 1372 | /* build transformed binding list */ |
| 1373 | SCM um_names = scm_reverse (rnames); |
| 1374 | SCM um_inits = unmemoize_exprs (SCM_CAR (cdr_expr), env); |
| 1375 | SCM um_steps = unmemoize_exprs (SCM_CDR (cddddr_expr), extended_env); |
| 1376 | SCM um_bindings = SCM_EOL; |
| 1377 | while (!scm_is_null (um_names)) |
| 1378 | { |
| 1379 | const SCM name = SCM_CAR (um_names); |
| 1380 | const SCM init = SCM_CAR (um_inits); |
| 1381 | SCM step = SCM_CAR (um_steps); |
| 1382 | step = scm_is_eq (step, name) ? SCM_EOL : scm_list_1 (step); |
| 1383 | |
| 1384 | um_bindings = scm_cons (scm_cons2 (name, init, step), um_bindings); |
| 1385 | |
| 1386 | um_names = SCM_CDR (um_names); |
| 1387 | um_inits = SCM_CDR (um_inits); |
| 1388 | um_steps = SCM_CDR (um_steps); |
| 1389 | } |
| 1390 | um_bindings = scm_reverse_x (um_bindings, SCM_UNDEFINED); |
| 1391 | |
| 1392 | return scm_cons (scm_sym_do, |
| 1393 | scm_cons2 (um_bindings, um_exit_sequence, um_body)); |
| 1394 | } |
| 1395 | |
| 1396 | |
| 1397 | SCM_SYNTAX (s_if, "if", scm_i_makbimacro, scm_m_if); |
| 1398 | SCM_GLOBAL_SYMBOL (scm_sym_if, s_if); |
| 1399 | |
| 1400 | SCM |
| 1401 | scm_m_if (SCM expr, SCM env SCM_UNUSED) |
| 1402 | { |
| 1403 | const SCM cdr_expr = SCM_CDR (expr); |
| 1404 | const long length = scm_ilength (cdr_expr); |
| 1405 | ASSERT_SYNTAX (length == 2 || length == 3, s_expression, expr); |
| 1406 | SCM_SETCAR (expr, SCM_IM_IF); |
| 1407 | return expr; |
| 1408 | } |
| 1409 | |
| 1410 | static SCM |
| 1411 | unmemoize_if (const SCM expr, const SCM env) |
| 1412 | { |
| 1413 | const SCM cdr_expr = SCM_CDR (expr); |
| 1414 | const SCM um_condition = unmemoize_expression (SCM_CAR (cdr_expr), env); |
| 1415 | const SCM cddr_expr = SCM_CDR (cdr_expr); |
| 1416 | const SCM um_then = unmemoize_expression (SCM_CAR (cddr_expr), env); |
| 1417 | const SCM cdddr_expr = SCM_CDR (cddr_expr); |
| 1418 | |
| 1419 | if (scm_is_null (cdddr_expr)) |
| 1420 | { |
| 1421 | return scm_list_3 (scm_sym_if, um_condition, um_then); |
| 1422 | } |
| 1423 | else |
| 1424 | { |
| 1425 | const SCM um_else = unmemoize_expression (SCM_CAR (cdddr_expr), env); |
| 1426 | return scm_list_4 (scm_sym_if, um_condition, um_then, um_else); |
| 1427 | } |
| 1428 | } |
| 1429 | |
| 1430 | |
| 1431 | SCM_SYNTAX (s_lambda, "lambda", scm_i_makbimacro, scm_m_lambda); |
| 1432 | SCM_GLOBAL_SYMBOL (scm_sym_lambda, s_lambda); |
| 1433 | |
| 1434 | /* A helper function for memoize_lambda to support checking for duplicate |
| 1435 | * formal arguments: Return true if OBJ is `eq?' to one of the elements of |
| 1436 | * LIST or to the cdr of the last cons. Therefore, LIST may have any of the |
| 1437 | * forms that a formal argument can have: |
| 1438 | * <rest>, (<arg1> ...), (<arg1> ... . <rest>) */ |
| 1439 | static int |
| 1440 | c_improper_memq (SCM obj, SCM list) |
| 1441 | { |
| 1442 | for (; scm_is_pair (list); list = SCM_CDR (list)) |
| 1443 | { |
| 1444 | if (scm_is_eq (SCM_CAR (list), obj)) |
| 1445 | return 1; |
| 1446 | } |
| 1447 | return scm_is_eq (list, obj); |
| 1448 | } |
| 1449 | |
| 1450 | SCM |
| 1451 | scm_m_lambda (SCM expr, SCM env SCM_UNUSED) |
| 1452 | { |
| 1453 | SCM formals; |
| 1454 | SCM formals_idx; |
| 1455 | SCM cddr_expr; |
| 1456 | int documentation; |
| 1457 | SCM body; |
| 1458 | SCM new_body; |
| 1459 | |
| 1460 | const SCM cdr_expr = SCM_CDR (expr); |
| 1461 | const long length = scm_ilength (cdr_expr); |
| 1462 | ASSERT_SYNTAX (length >= 0, s_bad_expression, expr); |
| 1463 | ASSERT_SYNTAX (length >= 2, s_missing_expression, expr); |
| 1464 | |
| 1465 | /* Before iterating the list of formal arguments, make sure the formals |
| 1466 | * actually are given as either a symbol or a non-cyclic list. */ |
| 1467 | formals = SCM_CAR (cdr_expr); |
| 1468 | if (scm_is_pair (formals)) |
| 1469 | { |
| 1470 | /* Dirk:FIXME:: We should check for a cyclic list of formals, and if |
| 1471 | * detected, report a 'Bad formals' error. */ |
| 1472 | } |
| 1473 | else |
| 1474 | { |
| 1475 | ASSERT_SYNTAX_2 (scm_is_symbol (formals) || scm_is_null (formals), |
| 1476 | s_bad_formals, formals, expr); |
| 1477 | } |
| 1478 | |
| 1479 | /* Now iterate the list of formal arguments to check if all formals are |
| 1480 | * symbols, and that there are no duplicates. */ |
| 1481 | formals_idx = formals; |
| 1482 | while (scm_is_pair (formals_idx)) |
| 1483 | { |
| 1484 | const SCM formal = SCM_CAR (formals_idx); |
| 1485 | const SCM next_idx = SCM_CDR (formals_idx); |
| 1486 | ASSERT_SYNTAX_2 (scm_is_symbol (formal), s_bad_formal, formal, expr); |
| 1487 | ASSERT_SYNTAX_2 (!c_improper_memq (formal, next_idx), |
| 1488 | s_duplicate_formal, formal, expr); |
| 1489 | formals_idx = next_idx; |
| 1490 | } |
| 1491 | ASSERT_SYNTAX_2 (scm_is_null (formals_idx) || scm_is_symbol (formals_idx), |
| 1492 | s_bad_formal, formals_idx, expr); |
| 1493 | |
| 1494 | /* Memoize the body. Keep a potential documentation string. */ |
| 1495 | /* Dirk:FIXME:: We should probably extract the documentation string to |
| 1496 | * some external database. Otherwise it will slow down execution, since |
| 1497 | * the documentation string will have to be skipped with every execution |
| 1498 | * of the closure. */ |
| 1499 | cddr_expr = SCM_CDR (cdr_expr); |
| 1500 | documentation = (length >= 3 && scm_is_string (SCM_CAR (cddr_expr))); |
| 1501 | body = documentation ? SCM_CDR (cddr_expr) : cddr_expr; |
| 1502 | new_body = m_body (SCM_IM_LAMBDA, body); |
| 1503 | |
| 1504 | SCM_SETCAR (expr, SCM_IM_LAMBDA); |
| 1505 | if (documentation) |
| 1506 | SCM_SETCDR (cddr_expr, new_body); |
| 1507 | else |
| 1508 | SCM_SETCDR (cdr_expr, new_body); |
| 1509 | return expr; |
| 1510 | } |
| 1511 | |
| 1512 | static SCM |
| 1513 | unmemoize_lambda (const SCM expr, const SCM env) |
| 1514 | { |
| 1515 | const SCM formals = SCM_CADR (expr); |
| 1516 | const SCM body = SCM_CDDR (expr); |
| 1517 | |
| 1518 | const SCM new_env = SCM_EXTEND_ENV (formals, SCM_EOL, env); |
| 1519 | const SCM um_formals = scm_i_finite_list_copy (formals); |
| 1520 | const SCM um_body = unmemoize_exprs (body, new_env); |
| 1521 | |
| 1522 | return scm_cons2 (scm_sym_lambda, um_formals, um_body); |
| 1523 | } |
| 1524 | |
| 1525 | |
| 1526 | /* Check if the format of the bindings is ((<symbol> <init-form>) ...). */ |
| 1527 | static void |
| 1528 | check_bindings (const SCM bindings, const SCM expr) |
| 1529 | { |
| 1530 | SCM binding_idx; |
| 1531 | |
| 1532 | ASSERT_SYNTAX_2 (scm_ilength (bindings) >= 0, |
| 1533 | s_bad_bindings, bindings, expr); |
| 1534 | |
| 1535 | binding_idx = bindings; |
| 1536 | for (; !scm_is_null (binding_idx); binding_idx = SCM_CDR (binding_idx)) |
| 1537 | { |
| 1538 | SCM name; /* const */ |
| 1539 | |
| 1540 | const SCM binding = SCM_CAR (binding_idx); |
| 1541 | ASSERT_SYNTAX_2 (scm_ilength (binding) == 2, |
| 1542 | s_bad_binding, binding, expr); |
| 1543 | |
| 1544 | name = SCM_CAR (binding); |
| 1545 | ASSERT_SYNTAX_2 (scm_is_symbol (name), s_bad_variable, name, expr); |
| 1546 | } |
| 1547 | } |
| 1548 | |
| 1549 | |
| 1550 | /* The bindings, which must have the format ((v1 i1) (v2 i2) ... (vn in)), are |
| 1551 | * transformed to the lists (vn ... v2 v1) and (i1 i2 ... in). That is, the |
| 1552 | * variables are returned in a list with their order reversed, and the init |
| 1553 | * forms are returned in a list in the same order as they are given in the |
| 1554 | * bindings. If a duplicate variable name is detected, an error is |
| 1555 | * signalled. */ |
| 1556 | static void |
| 1557 | transform_bindings ( |
| 1558 | const SCM bindings, const SCM expr, |
| 1559 | SCM *const rvarptr, SCM *const initptr ) |
| 1560 | { |
| 1561 | SCM rvariables = SCM_EOL; |
| 1562 | SCM rinits = SCM_EOL; |
| 1563 | SCM binding_idx = bindings; |
| 1564 | for (; !scm_is_null (binding_idx); binding_idx = SCM_CDR (binding_idx)) |
| 1565 | { |
| 1566 | const SCM binding = SCM_CAR (binding_idx); |
| 1567 | const SCM cdr_binding = SCM_CDR (binding); |
| 1568 | const SCM name = SCM_CAR (binding); |
| 1569 | ASSERT_SYNTAX_2 (scm_is_false (scm_c_memq (name, rvariables)), |
| 1570 | s_duplicate_binding, name, expr); |
| 1571 | rvariables = scm_cons (name, rvariables); |
| 1572 | rinits = scm_cons (SCM_CAR (cdr_binding), rinits); |
| 1573 | } |
| 1574 | *rvarptr = rvariables; |
| 1575 | *initptr = scm_reverse_x (rinits, SCM_UNDEFINED); |
| 1576 | } |
| 1577 | |
| 1578 | |
| 1579 | SCM_SYNTAX(s_let, "let", scm_i_makbimacro, scm_m_let); |
| 1580 | SCM_GLOBAL_SYMBOL(scm_sym_let, s_let); |
| 1581 | |
| 1582 | /* This function is a helper function for memoize_let. It transforms |
| 1583 | * (let name ((var init) ...) body ...) into |
| 1584 | * ((letrec ((name (lambda (var ...) body ...))) name) init ...) |
| 1585 | * and memoizes the expression. It is assumed that the caller has checked |
| 1586 | * that name is a symbol and that there are bindings and a body. */ |
| 1587 | static SCM |
| 1588 | memoize_named_let (const SCM expr, const SCM env SCM_UNUSED) |
| 1589 | { |
| 1590 | SCM rvariables; |
| 1591 | SCM variables; |
| 1592 | SCM inits; |
| 1593 | |
| 1594 | const SCM cdr_expr = SCM_CDR (expr); |
| 1595 | const SCM name = SCM_CAR (cdr_expr); |
| 1596 | const SCM cddr_expr = SCM_CDR (cdr_expr); |
| 1597 | const SCM bindings = SCM_CAR (cddr_expr); |
| 1598 | check_bindings (bindings, expr); |
| 1599 | |
| 1600 | transform_bindings (bindings, expr, &rvariables, &inits); |
| 1601 | variables = scm_reverse_x (rvariables, SCM_UNDEFINED); |
| 1602 | |
| 1603 | { |
| 1604 | const SCM let_body = SCM_CDR (cddr_expr); |
| 1605 | const SCM lambda_body = m_body (SCM_IM_LET, let_body); |
| 1606 | const SCM lambda_tail = scm_cons (variables, lambda_body); |
| 1607 | const SCM lambda_form = scm_cons_source (expr, scm_sym_lambda, lambda_tail); |
| 1608 | |
| 1609 | const SCM rvar = scm_list_1 (name); |
| 1610 | const SCM init = scm_list_1 (lambda_form); |
| 1611 | const SCM body = m_body (SCM_IM_LET, scm_list_1 (name)); |
| 1612 | const SCM letrec_tail = scm_cons (rvar, scm_cons (init, body)); |
| 1613 | const SCM letrec_form = scm_cons_source (expr, SCM_IM_LETREC, letrec_tail); |
| 1614 | return scm_cons_source (expr, letrec_form, inits); |
| 1615 | } |
| 1616 | } |
| 1617 | |
| 1618 | /* (let ((v1 i1) (v2 i2) ...) body) with variables v1 .. vn and initializers |
| 1619 | * i1 .. in is transformed to (#@let (vn ... v2 v1) (i1 i2 ...) body). */ |
| 1620 | SCM |
| 1621 | scm_m_let (SCM expr, SCM env) |
| 1622 | { |
| 1623 | SCM bindings; |
| 1624 | |
| 1625 | const SCM cdr_expr = SCM_CDR (expr); |
| 1626 | const long length = scm_ilength (cdr_expr); |
| 1627 | ASSERT_SYNTAX (length >= 0, s_bad_expression, expr); |
| 1628 | ASSERT_SYNTAX (length >= 2, s_missing_expression, expr); |
| 1629 | |
| 1630 | bindings = SCM_CAR (cdr_expr); |
| 1631 | if (scm_is_symbol (bindings)) |
| 1632 | { |
| 1633 | ASSERT_SYNTAX (length >= 3, s_missing_expression, expr); |
| 1634 | return memoize_named_let (expr, env); |
| 1635 | } |
| 1636 | |
| 1637 | check_bindings (bindings, expr); |
| 1638 | if (scm_is_null (bindings) || scm_is_null (SCM_CDR (bindings))) |
| 1639 | { |
| 1640 | /* Special case: no bindings or single binding => let* is faster. */ |
| 1641 | const SCM body = m_body (SCM_IM_LET, SCM_CDR (cdr_expr)); |
| 1642 | return scm_m_letstar (scm_cons2 (SCM_CAR (expr), bindings, body), env); |
| 1643 | } |
| 1644 | else |
| 1645 | { |
| 1646 | /* plain let */ |
| 1647 | SCM rvariables; |
| 1648 | SCM inits; |
| 1649 | transform_bindings (bindings, expr, &rvariables, &inits); |
| 1650 | |
| 1651 | { |
| 1652 | const SCM new_body = m_body (SCM_IM_LET, SCM_CDR (cdr_expr)); |
| 1653 | const SCM new_tail = scm_cons2 (rvariables, inits, new_body); |
| 1654 | SCM_SETCAR (expr, SCM_IM_LET); |
| 1655 | SCM_SETCDR (expr, new_tail); |
| 1656 | return expr; |
| 1657 | } |
| 1658 | } |
| 1659 | } |
| 1660 | |
| 1661 | static SCM |
| 1662 | build_binding_list (SCM rnames, SCM rinits) |
| 1663 | { |
| 1664 | SCM bindings = SCM_EOL; |
| 1665 | while (!scm_is_null (rnames)) |
| 1666 | { |
| 1667 | const SCM binding = scm_list_2 (SCM_CAR (rnames), SCM_CAR (rinits)); |
| 1668 | bindings = scm_cons (binding, bindings); |
| 1669 | rnames = SCM_CDR (rnames); |
| 1670 | rinits = SCM_CDR (rinits); |
| 1671 | } |
| 1672 | return bindings; |
| 1673 | } |
| 1674 | |
| 1675 | static SCM |
| 1676 | unmemoize_let (const SCM expr, const SCM env) |
| 1677 | { |
| 1678 | const SCM cdr_expr = SCM_CDR (expr); |
| 1679 | const SCM um_rnames = SCM_CAR (cdr_expr); |
| 1680 | const SCM extended_env = SCM_EXTEND_ENV (um_rnames, SCM_EOL, env); |
| 1681 | const SCM cddr_expr = SCM_CDR (cdr_expr); |
| 1682 | const SCM um_inits = unmemoize_exprs (SCM_CAR (cddr_expr), env); |
| 1683 | const SCM um_rinits = scm_reverse_x (um_inits, SCM_UNDEFINED); |
| 1684 | const SCM um_bindings = build_binding_list (um_rnames, um_rinits); |
| 1685 | const SCM um_body = unmemoize_exprs (SCM_CDR (cddr_expr), extended_env); |
| 1686 | |
| 1687 | return scm_cons2 (scm_sym_let, um_bindings, um_body); |
| 1688 | } |
| 1689 | |
| 1690 | |
| 1691 | SCM_SYNTAX(s_letrec, "letrec", scm_i_makbimacro, scm_m_letrec); |
| 1692 | SCM_GLOBAL_SYMBOL(scm_sym_letrec, s_letrec); |
| 1693 | |
| 1694 | SCM |
| 1695 | scm_m_letrec (SCM expr, SCM env) |
| 1696 | { |
| 1697 | SCM bindings; |
| 1698 | |
| 1699 | const SCM cdr_expr = SCM_CDR (expr); |
| 1700 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1701 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 2, s_missing_expression, expr); |
| 1702 | |
| 1703 | bindings = SCM_CAR (cdr_expr); |
| 1704 | if (scm_is_null (bindings)) |
| 1705 | { |
| 1706 | /* no bindings, let* is executed faster */ |
| 1707 | SCM body = m_body (SCM_IM_LETREC, SCM_CDR (cdr_expr)); |
| 1708 | return scm_m_letstar (scm_cons2 (SCM_CAR (expr), SCM_EOL, body), env); |
| 1709 | } |
| 1710 | else |
| 1711 | { |
| 1712 | SCM rvariables; |
| 1713 | SCM inits; |
| 1714 | SCM new_body; |
| 1715 | |
| 1716 | check_bindings (bindings, expr); |
| 1717 | transform_bindings (bindings, expr, &rvariables, &inits); |
| 1718 | new_body = m_body (SCM_IM_LETREC, SCM_CDR (cdr_expr)); |
| 1719 | return scm_cons2 (SCM_IM_LETREC, rvariables, scm_cons (inits, new_body)); |
| 1720 | } |
| 1721 | } |
| 1722 | |
| 1723 | static SCM |
| 1724 | unmemoize_letrec (const SCM expr, const SCM env) |
| 1725 | { |
| 1726 | const SCM cdr_expr = SCM_CDR (expr); |
| 1727 | const SCM um_rnames = SCM_CAR (cdr_expr); |
| 1728 | const SCM extended_env = SCM_EXTEND_ENV (um_rnames, SCM_EOL, env); |
| 1729 | const SCM cddr_expr = SCM_CDR (cdr_expr); |
| 1730 | const SCM um_inits = unmemoize_exprs (SCM_CAR (cddr_expr), extended_env); |
| 1731 | const SCM um_rinits = scm_reverse_x (um_inits, SCM_UNDEFINED); |
| 1732 | const SCM um_bindings = build_binding_list (um_rnames, um_rinits); |
| 1733 | const SCM um_body = unmemoize_exprs (SCM_CDR (cddr_expr), extended_env); |
| 1734 | |
| 1735 | return scm_cons2 (scm_sym_letrec, um_bindings, um_body); |
| 1736 | } |
| 1737 | |
| 1738 | |
| 1739 | |
| 1740 | SCM_SYNTAX (s_letstar, "let*", scm_i_makbimacro, scm_m_letstar); |
| 1741 | SCM_GLOBAL_SYMBOL (scm_sym_letstar, s_letstar); |
| 1742 | |
| 1743 | /* (let* ((v1 i1) (v2 i2) ...) body) with variables v1 .. vn and initializers |
| 1744 | * i1 .. in is transformed into the form (#@let* (v1 i1 v2 i2 ...) body). */ |
| 1745 | SCM |
| 1746 | scm_m_letstar (SCM expr, SCM env SCM_UNUSED) |
| 1747 | { |
| 1748 | SCM binding_idx; |
| 1749 | SCM new_body; |
| 1750 | |
| 1751 | const SCM cdr_expr = SCM_CDR (expr); |
| 1752 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1753 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 2, s_missing_expression, expr); |
| 1754 | |
| 1755 | binding_idx = SCM_CAR (cdr_expr); |
| 1756 | check_bindings (binding_idx, expr); |
| 1757 | |
| 1758 | /* Transform ((v1 i1) (v2 i2) ...) into (v1 i1 v2 i2 ...). The |
| 1759 | * transformation is done in place. At the beginning of one iteration of |
| 1760 | * the loop the variable binding_idx holds the form |
| 1761 | * P1:( (vn . P2:(in . ())) . P3:( (vn+1 in+1) ... ) ), |
| 1762 | * where P1, P2 and P3 indicate the pairs, that are relevant for the |
| 1763 | * transformation. P1 and P2 are modified in the loop, P3 remains |
| 1764 | * untouched. After the execution of the loop, P1 will hold |
| 1765 | * P1:( vn . P2:(in . P3:( (vn+1 in+1) ... )) ) |
| 1766 | * and binding_idx will hold P3. */ |
| 1767 | while (!scm_is_null (binding_idx)) |
| 1768 | { |
| 1769 | const SCM cdr_binding_idx = SCM_CDR (binding_idx); /* remember P3 */ |
| 1770 | const SCM binding = SCM_CAR (binding_idx); |
| 1771 | const SCM name = SCM_CAR (binding); |
| 1772 | const SCM cdr_binding = SCM_CDR (binding); |
| 1773 | |
| 1774 | SCM_SETCDR (cdr_binding, cdr_binding_idx); /* update P2 */ |
| 1775 | SCM_SETCAR (binding_idx, name); /* update P1 */ |
| 1776 | SCM_SETCDR (binding_idx, cdr_binding); /* update P1 */ |
| 1777 | |
| 1778 | binding_idx = cdr_binding_idx; /* continue with P3 */ |
| 1779 | } |
| 1780 | |
| 1781 | new_body = m_body (SCM_IM_LETSTAR, SCM_CDR (cdr_expr)); |
| 1782 | SCM_SETCAR (expr, SCM_IM_LETSTAR); |
| 1783 | /* the bindings have been changed in place */ |
| 1784 | SCM_SETCDR (cdr_expr, new_body); |
| 1785 | return expr; |
| 1786 | } |
| 1787 | |
| 1788 | static SCM |
| 1789 | unmemoize_letstar (const SCM expr, const SCM env) |
| 1790 | { |
| 1791 | const SCM cdr_expr = SCM_CDR (expr); |
| 1792 | const SCM body = SCM_CDR (cdr_expr); |
| 1793 | SCM bindings = SCM_CAR (cdr_expr); |
| 1794 | SCM um_bindings = SCM_EOL; |
| 1795 | SCM extended_env = env; |
| 1796 | SCM um_body; |
| 1797 | |
| 1798 | while (!scm_is_null (bindings)) |
| 1799 | { |
| 1800 | const SCM variable = SCM_CAR (bindings); |
| 1801 | const SCM init = SCM_CADR (bindings); |
| 1802 | const SCM um_init = unmemoize_expression (init, extended_env); |
| 1803 | um_bindings = scm_cons (scm_list_2 (variable, um_init), um_bindings); |
| 1804 | extended_env = SCM_EXTEND_ENV (variable, SCM_BOOL_F, extended_env); |
| 1805 | bindings = SCM_CDDR (bindings); |
| 1806 | } |
| 1807 | um_bindings = scm_reverse_x (um_bindings, SCM_UNDEFINED); |
| 1808 | |
| 1809 | um_body = unmemoize_exprs (body, extended_env); |
| 1810 | |
| 1811 | return scm_cons2 (scm_sym_letstar, um_bindings, um_body); |
| 1812 | } |
| 1813 | |
| 1814 | |
| 1815 | SCM_SYNTAX (s_or, "or", scm_i_makbimacro, scm_m_or); |
| 1816 | SCM_GLOBAL_SYMBOL (scm_sym_or, s_or); |
| 1817 | |
| 1818 | SCM |
| 1819 | scm_m_or (SCM expr, SCM env SCM_UNUSED) |
| 1820 | { |
| 1821 | const SCM cdr_expr = SCM_CDR (expr); |
| 1822 | const long length = scm_ilength (cdr_expr); |
| 1823 | |
| 1824 | ASSERT_SYNTAX (length >= 0, s_bad_expression, expr); |
| 1825 | |
| 1826 | if (length == 0) |
| 1827 | { |
| 1828 | /* Special case: (or) is replaced by #f. */ |
| 1829 | return SCM_BOOL_F; |
| 1830 | } |
| 1831 | else |
| 1832 | { |
| 1833 | SCM_SETCAR (expr, SCM_IM_OR); |
| 1834 | return expr; |
| 1835 | } |
| 1836 | } |
| 1837 | |
| 1838 | static SCM |
| 1839 | unmemoize_or (const SCM expr, const SCM env) |
| 1840 | { |
| 1841 | return scm_cons (scm_sym_or, unmemoize_exprs (SCM_CDR (expr), env)); |
| 1842 | } |
| 1843 | |
| 1844 | |
| 1845 | SCM_SYNTAX (s_quasiquote, "quasiquote", scm_makacro, scm_m_quasiquote); |
| 1846 | SCM_GLOBAL_SYMBOL (scm_sym_quasiquote, s_quasiquote); |
| 1847 | SCM_GLOBAL_SYMBOL (scm_sym_unquote, "unquote"); |
| 1848 | SCM_GLOBAL_SYMBOL (scm_sym_uq_splicing, "unquote-splicing"); |
| 1849 | |
| 1850 | /* Internal function to handle a quasiquotation: 'form' is the parameter in |
| 1851 | * the call (quasiquotation form), 'env' is the environment where unquoted |
| 1852 | * expressions will be evaluated, and 'depth' is the current quasiquotation |
| 1853 | * nesting level and is known to be greater than zero. */ |
| 1854 | static SCM |
| 1855 | iqq (SCM form, SCM env, unsigned long int depth) |
| 1856 | { |
| 1857 | if (scm_is_pair (form)) |
| 1858 | { |
| 1859 | const SCM tmp = SCM_CAR (form); |
| 1860 | if (scm_is_eq (tmp, scm_sym_quasiquote)) |
| 1861 | { |
| 1862 | const SCM args = SCM_CDR (form); |
| 1863 | ASSERT_SYNTAX (scm_ilength (args) == 1, s_expression, form); |
| 1864 | return scm_list_2 (tmp, iqq (SCM_CAR (args), env, depth + 1)); |
| 1865 | } |
| 1866 | else if (scm_is_eq (tmp, scm_sym_unquote)) |
| 1867 | { |
| 1868 | const SCM args = SCM_CDR (form); |
| 1869 | ASSERT_SYNTAX (scm_ilength (args) == 1, s_expression, form); |
| 1870 | if (depth - 1 == 0) |
| 1871 | return scm_eval_car (args, env); |
| 1872 | else |
| 1873 | return scm_list_2 (tmp, iqq (SCM_CAR (args), env, depth - 1)); |
| 1874 | } |
| 1875 | else if (scm_is_pair (tmp) |
| 1876 | && scm_is_eq (SCM_CAR (tmp), scm_sym_uq_splicing)) |
| 1877 | { |
| 1878 | const SCM args = SCM_CDR (tmp); |
| 1879 | ASSERT_SYNTAX (scm_ilength (args) == 1, s_expression, form); |
| 1880 | if (depth - 1 == 0) |
| 1881 | { |
| 1882 | const SCM list = scm_eval_car (args, env); |
| 1883 | const SCM rest = SCM_CDR (form); |
| 1884 | ASSERT_SYNTAX_2 (scm_ilength (list) >= 0, |
| 1885 | s_splicing, list, form); |
| 1886 | return scm_append (scm_list_2 (list, iqq (rest, env, depth))); |
| 1887 | } |
| 1888 | else |
| 1889 | return scm_cons (iqq (SCM_CAR (form), env, depth - 1), |
| 1890 | iqq (SCM_CDR (form), env, depth)); |
| 1891 | } |
| 1892 | else |
| 1893 | return scm_cons (iqq (SCM_CAR (form), env, depth), |
| 1894 | iqq (SCM_CDR (form), env, depth)); |
| 1895 | } |
| 1896 | else if (scm_is_vector (form)) |
| 1897 | return scm_vector (iqq (scm_vector_to_list (form), env, depth)); |
| 1898 | else |
| 1899 | return form; |
| 1900 | } |
| 1901 | |
| 1902 | SCM |
| 1903 | scm_m_quasiquote (SCM expr, SCM env) |
| 1904 | { |
| 1905 | const SCM cdr_expr = SCM_CDR (expr); |
| 1906 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1907 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 1, s_expression, expr); |
| 1908 | return iqq (SCM_CAR (cdr_expr), env, 1); |
| 1909 | } |
| 1910 | |
| 1911 | |
| 1912 | SCM_SYNTAX (s_quote, "quote", scm_i_makbimacro, scm_m_quote); |
| 1913 | SCM_GLOBAL_SYMBOL (scm_sym_quote, s_quote); |
| 1914 | |
| 1915 | SCM |
| 1916 | scm_m_quote (SCM expr, SCM env SCM_UNUSED) |
| 1917 | { |
| 1918 | SCM quotee; |
| 1919 | |
| 1920 | const SCM cdr_expr = SCM_CDR (expr); |
| 1921 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1922 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 1, s_expression, expr); |
| 1923 | quotee = SCM_CAR (cdr_expr); |
| 1924 | if (is_self_quoting_p (quotee)) |
| 1925 | return quotee; |
| 1926 | |
| 1927 | SCM_SETCAR (expr, SCM_IM_QUOTE); |
| 1928 | SCM_SETCDR (expr, quotee); |
| 1929 | return expr; |
| 1930 | } |
| 1931 | |
| 1932 | static SCM |
| 1933 | unmemoize_quote (const SCM expr, const SCM env SCM_UNUSED) |
| 1934 | { |
| 1935 | return scm_list_2 (scm_sym_quote, SCM_CDR (expr)); |
| 1936 | } |
| 1937 | |
| 1938 | |
| 1939 | /* Will go into the RnRS module when Guile is factorized. |
| 1940 | SCM_SYNTAX (s_set_x, "set!", scm_i_makbimacro, scm_m_set_x); */ |
| 1941 | static const char s_set_x[] = "set!"; |
| 1942 | SCM_GLOBAL_SYMBOL (scm_sym_set_x, s_set_x); |
| 1943 | |
| 1944 | SCM |
| 1945 | scm_m_set_x (SCM expr, SCM env SCM_UNUSED) |
| 1946 | { |
| 1947 | SCM variable; |
| 1948 | SCM new_variable; |
| 1949 | |
| 1950 | const SCM cdr_expr = SCM_CDR (expr); |
| 1951 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1952 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 2, s_expression, expr); |
| 1953 | variable = SCM_CAR (cdr_expr); |
| 1954 | |
| 1955 | /* Memoize the variable form. */ |
| 1956 | ASSERT_SYNTAX_2 (scm_is_symbol (variable), s_bad_variable, variable, expr); |
| 1957 | new_variable = lookup_symbol (variable, env); |
| 1958 | /* Leave the memoization of unbound symbols to lazy memoization: */ |
| 1959 | if (SCM_UNBNDP (new_variable)) |
| 1960 | new_variable = variable; |
| 1961 | |
| 1962 | SCM_SETCAR (expr, SCM_IM_SET_X); |
| 1963 | SCM_SETCAR (cdr_expr, new_variable); |
| 1964 | return expr; |
| 1965 | } |
| 1966 | |
| 1967 | static SCM |
| 1968 | unmemoize_set_x (const SCM expr, const SCM env) |
| 1969 | { |
| 1970 | return scm_cons (scm_sym_set_x, unmemoize_exprs (SCM_CDR (expr), env)); |
| 1971 | } |
| 1972 | |
| 1973 | |
| 1974 | /* Start of the memoizers for non-R5RS builtin macros. */ |
| 1975 | |
| 1976 | |
| 1977 | SCM_SYNTAX (s_atapply, "@apply", scm_i_makbimacro, scm_m_apply); |
| 1978 | SCM_GLOBAL_SYMBOL (scm_sym_atapply, s_atapply); |
| 1979 | SCM_GLOBAL_SYMBOL (scm_sym_apply, s_atapply + 1); |
| 1980 | |
| 1981 | SCM |
| 1982 | scm_m_apply (SCM expr, SCM env SCM_UNUSED) |
| 1983 | { |
| 1984 | const SCM cdr_expr = SCM_CDR (expr); |
| 1985 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 1986 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 2, s_missing_expression, expr); |
| 1987 | |
| 1988 | SCM_SETCAR (expr, SCM_IM_APPLY); |
| 1989 | return expr; |
| 1990 | } |
| 1991 | |
| 1992 | static SCM |
| 1993 | unmemoize_apply (const SCM expr, const SCM env) |
| 1994 | { |
| 1995 | return scm_list_2 (scm_sym_atapply, unmemoize_exprs (SCM_CDR (expr), env)); |
| 1996 | } |
| 1997 | |
| 1998 | |
| 1999 | SCM_SYNTAX (s_atbind, "@bind", scm_i_makbimacro, scm_m_atbind); |
| 2000 | |
| 2001 | /* FIXME: The following explanation should go into the documentation: */ |
| 2002 | /* (@bind ((var init) ...) body ...) will assign the values of the `init's to |
| 2003 | * the global variables named by `var's (symbols, not evaluated), creating |
| 2004 | * them if they don't exist, executes body, and then restores the previous |
| 2005 | * values of the `var's. Additionally, whenever control leaves body, the |
| 2006 | * values of the `var's are saved and restored when control returns. It is an |
| 2007 | * error when a symbol appears more than once among the `var's. All `init's |
| 2008 | * are evaluated before any `var' is set. |
| 2009 | * |
| 2010 | * Think of this as `let' for dynamic scope. |
| 2011 | */ |
| 2012 | |
| 2013 | /* (@bind ((var1 exp1) ... (varn expn)) body ...) is memoized into |
| 2014 | * (#@bind ((varn ... var1) . (exp1 ... expn)) body ...). |
| 2015 | * |
| 2016 | * FIXME - also implement `@bind*'. |
| 2017 | */ |
| 2018 | SCM |
| 2019 | scm_m_atbind (SCM expr, SCM env) |
| 2020 | { |
| 2021 | SCM bindings; |
| 2022 | SCM rvariables; |
| 2023 | SCM inits; |
| 2024 | SCM variable_idx; |
| 2025 | |
| 2026 | const SCM top_level = scm_env_top_level (env); |
| 2027 | |
| 2028 | const SCM cdr_expr = SCM_CDR (expr); |
| 2029 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2030 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 2, s_missing_expression, expr); |
| 2031 | bindings = SCM_CAR (cdr_expr); |
| 2032 | check_bindings (bindings, expr); |
| 2033 | transform_bindings (bindings, expr, &rvariables, &inits); |
| 2034 | |
| 2035 | for (variable_idx = rvariables; |
| 2036 | !scm_is_null (variable_idx); |
| 2037 | variable_idx = SCM_CDR (variable_idx)) |
| 2038 | { |
| 2039 | /* The first call to scm_sym2var will look beyond the current module, |
| 2040 | * while the second call wont. */ |
| 2041 | const SCM variable = SCM_CAR (variable_idx); |
| 2042 | SCM new_variable = scm_sym2var (variable, top_level, SCM_BOOL_F); |
| 2043 | if (scm_is_false (new_variable)) |
| 2044 | new_variable = scm_sym2var (variable, top_level, SCM_BOOL_T); |
| 2045 | SCM_SETCAR (variable_idx, new_variable); |
| 2046 | } |
| 2047 | |
| 2048 | SCM_SETCAR (expr, SCM_IM_BIND); |
| 2049 | SCM_SETCAR (cdr_expr, scm_cons (rvariables, inits)); |
| 2050 | return expr; |
| 2051 | } |
| 2052 | |
| 2053 | |
| 2054 | SCM_SYNTAX(s_atcall_cc, "@call-with-current-continuation", scm_i_makbimacro, scm_m_cont); |
| 2055 | SCM_GLOBAL_SYMBOL(scm_sym_atcall_cc, s_atcall_cc); |
| 2056 | |
| 2057 | SCM |
| 2058 | scm_m_cont (SCM expr, SCM env SCM_UNUSED) |
| 2059 | { |
| 2060 | const SCM cdr_expr = SCM_CDR (expr); |
| 2061 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2062 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 1, s_expression, expr); |
| 2063 | |
| 2064 | SCM_SETCAR (expr, SCM_IM_CONT); |
| 2065 | return expr; |
| 2066 | } |
| 2067 | |
| 2068 | static SCM |
| 2069 | unmemoize_atcall_cc (const SCM expr, const SCM env) |
| 2070 | { |
| 2071 | return scm_list_2 (scm_sym_atcall_cc, unmemoize_exprs (SCM_CDR (expr), env)); |
| 2072 | } |
| 2073 | |
| 2074 | |
| 2075 | SCM_SYNTAX (s_at_call_with_values, "@call-with-values", scm_i_makbimacro, scm_m_at_call_with_values); |
| 2076 | SCM_GLOBAL_SYMBOL(scm_sym_at_call_with_values, s_at_call_with_values); |
| 2077 | |
| 2078 | SCM |
| 2079 | scm_m_at_call_with_values (SCM expr, SCM env SCM_UNUSED) |
| 2080 | { |
| 2081 | const SCM cdr_expr = SCM_CDR (expr); |
| 2082 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2083 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 2, s_expression, expr); |
| 2084 | |
| 2085 | SCM_SETCAR (expr, SCM_IM_CALL_WITH_VALUES); |
| 2086 | return expr; |
| 2087 | } |
| 2088 | |
| 2089 | static SCM |
| 2090 | unmemoize_at_call_with_values (const SCM expr, const SCM env) |
| 2091 | { |
| 2092 | return scm_list_2 (scm_sym_at_call_with_values, |
| 2093 | unmemoize_exprs (SCM_CDR (expr), env)); |
| 2094 | } |
| 2095 | |
| 2096 | #if 0 |
| 2097 | |
| 2098 | /* See futures.h for a comment why futures are not enabled. |
| 2099 | */ |
| 2100 | |
| 2101 | SCM_SYNTAX (s_future, "future", scm_i_makbimacro, scm_m_future); |
| 2102 | SCM_GLOBAL_SYMBOL (scm_sym_future, s_future); |
| 2103 | |
| 2104 | /* Like promises, futures are implemented as closures with an empty |
| 2105 | * parameter list. Thus, (future <expression>) is transformed into |
| 2106 | * (#@future '() <expression>), where the empty list represents the |
| 2107 | * empty parameter list. This representation allows for easy creation |
| 2108 | * of the closure during evaluation. */ |
| 2109 | SCM |
| 2110 | scm_m_future (SCM expr, SCM env) |
| 2111 | { |
| 2112 | const SCM new_expr = memoize_as_thunk_prototype (expr, env); |
| 2113 | SCM_SETCAR (new_expr, SCM_IM_FUTURE); |
| 2114 | return new_expr; |
| 2115 | } |
| 2116 | |
| 2117 | static SCM |
| 2118 | unmemoize_future (const SCM expr, const SCM env) |
| 2119 | { |
| 2120 | const SCM thunk_expr = SCM_CADDR (expr); |
| 2121 | return scm_list_2 (scm_sym_future, unmemoize_expression (thunk_expr, env)); |
| 2122 | } |
| 2123 | |
| 2124 | #endif /* futures disabled. */ |
| 2125 | |
| 2126 | SCM_SYNTAX (s_gset_x, "set!", scm_i_makbimacro, scm_m_generalized_set_x); |
| 2127 | SCM_SYMBOL (scm_sym_setter, "setter"); |
| 2128 | |
| 2129 | SCM |
| 2130 | scm_m_generalized_set_x (SCM expr, SCM env) |
| 2131 | { |
| 2132 | SCM target, exp_target; |
| 2133 | |
| 2134 | const SCM cdr_expr = SCM_CDR (expr); |
| 2135 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2136 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 2, s_expression, expr); |
| 2137 | |
| 2138 | target = SCM_CAR (cdr_expr); |
| 2139 | if (!scm_is_pair (target)) |
| 2140 | { |
| 2141 | /* R5RS usage */ |
| 2142 | return scm_m_set_x (expr, env); |
| 2143 | } |
| 2144 | else |
| 2145 | { |
| 2146 | /* (set! (foo bar ...) baz) becomes ((setter foo) bar ... baz) */ |
| 2147 | /* Macroexpanding the target might return things of the form |
| 2148 | (begin <atom>). In that case, <atom> must be a symbol or a |
| 2149 | variable and we memoize to (set! <atom> ...). |
| 2150 | */ |
| 2151 | exp_target = macroexp (target, env); |
| 2152 | if (scm_is_eq (SCM_CAR (exp_target), SCM_IM_BEGIN) |
| 2153 | && !scm_is_null (SCM_CDR (exp_target)) |
| 2154 | && scm_is_null (SCM_CDDR (exp_target))) |
| 2155 | { |
| 2156 | exp_target= SCM_CADR (exp_target); |
| 2157 | ASSERT_SYNTAX_2 (scm_is_symbol (exp_target) |
| 2158 | || SCM_VARIABLEP (exp_target), |
| 2159 | s_bad_variable, exp_target, expr); |
| 2160 | return scm_cons (SCM_IM_SET_X, scm_cons (exp_target, |
| 2161 | SCM_CDR (cdr_expr))); |
| 2162 | } |
| 2163 | else |
| 2164 | { |
| 2165 | const SCM setter_proc_tail = scm_list_1 (SCM_CAR (target)); |
| 2166 | const SCM setter_proc = scm_cons_source (expr, scm_sym_setter, |
| 2167 | setter_proc_tail); |
| 2168 | |
| 2169 | const SCM cddr_expr = SCM_CDR (cdr_expr); |
| 2170 | const SCM setter_args = scm_append_x (scm_list_2 (SCM_CDR (target), |
| 2171 | cddr_expr)); |
| 2172 | |
| 2173 | SCM_SETCAR (expr, setter_proc); |
| 2174 | SCM_SETCDR (expr, setter_args); |
| 2175 | return expr; |
| 2176 | } |
| 2177 | } |
| 2178 | } |
| 2179 | |
| 2180 | |
| 2181 | /* @slot-ref is bound privately in the (oop goops) module from goops.c. As |
| 2182 | * soon as the module system allows us to more freely create bindings in |
| 2183 | * arbitrary modules during the startup phase, the code from goops.c should be |
| 2184 | * moved here. */ |
| 2185 | |
| 2186 | SCM_SYMBOL (sym_atslot_ref, "@slot-ref"); |
| 2187 | |
| 2188 | SCM |
| 2189 | scm_m_atslot_ref (SCM expr, SCM env SCM_UNUSED) |
| 2190 | { |
| 2191 | SCM slot_nr; |
| 2192 | |
| 2193 | const SCM cdr_expr = SCM_CDR (expr); |
| 2194 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2195 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 2, s_expression, expr); |
| 2196 | slot_nr = SCM_CADR (cdr_expr); |
| 2197 | ASSERT_SYNTAX_2 (SCM_I_INUMP (slot_nr), s_bad_slot_number, slot_nr, expr); |
| 2198 | |
| 2199 | SCM_SETCAR (expr, SCM_IM_SLOT_REF); |
| 2200 | SCM_SETCDR (cdr_expr, slot_nr); |
| 2201 | return expr; |
| 2202 | } |
| 2203 | |
| 2204 | static SCM |
| 2205 | unmemoize_atslot_ref (const SCM expr, const SCM env) |
| 2206 | { |
| 2207 | const SCM instance = SCM_CADR (expr); |
| 2208 | const SCM um_instance = unmemoize_expression (instance, env); |
| 2209 | const SCM slot_nr = SCM_CDDR (expr); |
| 2210 | return scm_list_3 (sym_atslot_ref, um_instance, slot_nr); |
| 2211 | } |
| 2212 | |
| 2213 | |
| 2214 | /* @slot-set! is bound privately in the (oop goops) module from goops.c. As |
| 2215 | * soon as the module system allows us to more freely create bindings in |
| 2216 | * arbitrary modules during the startup phase, the code from goops.c should be |
| 2217 | * moved here. */ |
| 2218 | |
| 2219 | SCM_SYMBOL (sym_atslot_set_x, "@slot-set!"); |
| 2220 | |
| 2221 | SCM |
| 2222 | scm_m_atslot_set_x (SCM expr, SCM env SCM_UNUSED) |
| 2223 | { |
| 2224 | SCM slot_nr; |
| 2225 | |
| 2226 | const SCM cdr_expr = SCM_CDR (expr); |
| 2227 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2228 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 3, s_expression, expr); |
| 2229 | slot_nr = SCM_CADR (cdr_expr); |
| 2230 | ASSERT_SYNTAX_2 (SCM_I_INUMP (slot_nr), s_bad_slot_number, slot_nr, expr); |
| 2231 | |
| 2232 | SCM_SETCAR (expr, SCM_IM_SLOT_SET_X); |
| 2233 | return expr; |
| 2234 | } |
| 2235 | |
| 2236 | static SCM |
| 2237 | unmemoize_atslot_set_x (const SCM expr, const SCM env) |
| 2238 | { |
| 2239 | const SCM cdr_expr = SCM_CDR (expr); |
| 2240 | const SCM instance = SCM_CAR (cdr_expr); |
| 2241 | const SCM um_instance = unmemoize_expression (instance, env); |
| 2242 | const SCM cddr_expr = SCM_CDR (cdr_expr); |
| 2243 | const SCM slot_nr = SCM_CAR (cddr_expr); |
| 2244 | const SCM cdddr_expr = SCM_CDR (cddr_expr); |
| 2245 | const SCM value = SCM_CAR (cdddr_expr); |
| 2246 | const SCM um_value = unmemoize_expression (value, env); |
| 2247 | return scm_list_4 (sym_atslot_set_x, um_instance, slot_nr, um_value); |
| 2248 | } |
| 2249 | |
| 2250 | |
| 2251 | #if SCM_ENABLE_ELISP |
| 2252 | |
| 2253 | static const char s_defun[] = "Symbol's function definition is void"; |
| 2254 | |
| 2255 | SCM_SYNTAX (s_nil_cond, "nil-cond", scm_i_makbimacro, scm_m_nil_cond); |
| 2256 | |
| 2257 | /* nil-cond expressions have the form |
| 2258 | * (nil-cond COND VAL COND VAL ... ELSEVAL) */ |
| 2259 | SCM |
| 2260 | scm_m_nil_cond (SCM expr, SCM env SCM_UNUSED) |
| 2261 | { |
| 2262 | const long length = scm_ilength (SCM_CDR (expr)); |
| 2263 | ASSERT_SYNTAX (length >= 0, s_bad_expression, expr); |
| 2264 | ASSERT_SYNTAX (length >= 1 && (length % 2) == 1, s_expression, expr); |
| 2265 | |
| 2266 | SCM_SETCAR (expr, SCM_IM_NIL_COND); |
| 2267 | return expr; |
| 2268 | } |
| 2269 | |
| 2270 | |
| 2271 | SCM_SYNTAX (s_atfop, "@fop", scm_i_makbimacro, scm_m_atfop); |
| 2272 | |
| 2273 | /* The @fop-macro handles procedure and macro applications for elisp. The |
| 2274 | * input expression must have the form |
| 2275 | * (@fop <var> (transformer-macro <expr> ...)) |
| 2276 | * where <var> must be a symbol. The expression is transformed into the |
| 2277 | * memoized form of either |
| 2278 | * (apply <un-aliased var> (transformer-macro <expr> ...)) |
| 2279 | * if the value of var (across all aliasing) is not a macro, or |
| 2280 | * (<un-aliased var> <expr> ...) |
| 2281 | * if var is a macro. */ |
| 2282 | SCM |
| 2283 | scm_m_atfop (SCM expr, SCM env SCM_UNUSED) |
| 2284 | { |
| 2285 | SCM location; |
| 2286 | SCM symbol; |
| 2287 | |
| 2288 | const SCM cdr_expr = SCM_CDR (expr); |
| 2289 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2290 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 1, s_missing_expression, expr); |
| 2291 | |
| 2292 | symbol = SCM_CAR (cdr_expr); |
| 2293 | ASSERT_SYNTAX_2 (scm_is_symbol (symbol), s_bad_variable, symbol, expr); |
| 2294 | |
| 2295 | location = scm_symbol_fref (symbol); |
| 2296 | ASSERT_SYNTAX_2 (SCM_VARIABLEP (location), s_defun, symbol, expr); |
| 2297 | |
| 2298 | /* The elisp function `defalias' allows to define aliases for symbols. To |
| 2299 | * look up such definitions, the chain of symbol definitions has to be |
| 2300 | * followed up to the terminal symbol. */ |
| 2301 | while (scm_is_symbol (SCM_VARIABLE_REF (location))) |
| 2302 | { |
| 2303 | const SCM alias = SCM_VARIABLE_REF (location); |
| 2304 | location = scm_symbol_fref (alias); |
| 2305 | ASSERT_SYNTAX_2 (SCM_VARIABLEP (location), s_defun, symbol, expr); |
| 2306 | } |
| 2307 | |
| 2308 | /* Memoize the value location belonging to the terminal symbol. */ |
| 2309 | SCM_SETCAR (cdr_expr, location); |
| 2310 | |
| 2311 | if (!SCM_MACROP (SCM_VARIABLE_REF (location))) |
| 2312 | { |
| 2313 | /* Since the location does not contain a macro, the form is a procedure |
| 2314 | * application. Replace `@fop' by `@apply' and transform the expression |
| 2315 | * including the `transformer-macro'. */ |
| 2316 | SCM_SETCAR (expr, SCM_IM_APPLY); |
| 2317 | return expr; |
| 2318 | } |
| 2319 | else |
| 2320 | { |
| 2321 | /* Since the location contains a macro, the arguments should not be |
| 2322 | * transformed, so the `transformer-macro' is cut out. The resulting |
| 2323 | * expression starts with the memoized variable, that is at the cdr of |
| 2324 | * the input expression. */ |
| 2325 | SCM_SETCDR (cdr_expr, SCM_CDADR (cdr_expr)); |
| 2326 | return cdr_expr; |
| 2327 | } |
| 2328 | } |
| 2329 | |
| 2330 | #endif /* SCM_ENABLE_ELISP */ |
| 2331 | |
| 2332 | |
| 2333 | static SCM |
| 2334 | unmemoize_builtin_macro (const SCM expr, const SCM env) |
| 2335 | { |
| 2336 | switch (ISYMNUM (SCM_CAR (expr))) |
| 2337 | { |
| 2338 | case (ISYMNUM (SCM_IM_AND)): |
| 2339 | return unmemoize_and (expr, env); |
| 2340 | |
| 2341 | case (ISYMNUM (SCM_IM_BEGIN)): |
| 2342 | return unmemoize_begin (expr, env); |
| 2343 | |
| 2344 | case (ISYMNUM (SCM_IM_CASE)): |
| 2345 | return unmemoize_case (expr, env); |
| 2346 | |
| 2347 | case (ISYMNUM (SCM_IM_COND)): |
| 2348 | return unmemoize_cond (expr, env); |
| 2349 | |
| 2350 | case (ISYMNUM (SCM_IM_DELAY)): |
| 2351 | return unmemoize_delay (expr, env); |
| 2352 | |
| 2353 | case (ISYMNUM (SCM_IM_DO)): |
| 2354 | return unmemoize_do (expr, env); |
| 2355 | |
| 2356 | case (ISYMNUM (SCM_IM_IF)): |
| 2357 | return unmemoize_if (expr, env); |
| 2358 | |
| 2359 | case (ISYMNUM (SCM_IM_LAMBDA)): |
| 2360 | return unmemoize_lambda (expr, env); |
| 2361 | |
| 2362 | case (ISYMNUM (SCM_IM_LET)): |
| 2363 | return unmemoize_let (expr, env); |
| 2364 | |
| 2365 | case (ISYMNUM (SCM_IM_LETREC)): |
| 2366 | return unmemoize_letrec (expr, env); |
| 2367 | |
| 2368 | case (ISYMNUM (SCM_IM_LETSTAR)): |
| 2369 | return unmemoize_letstar (expr, env); |
| 2370 | |
| 2371 | case (ISYMNUM (SCM_IM_OR)): |
| 2372 | return unmemoize_or (expr, env); |
| 2373 | |
| 2374 | case (ISYMNUM (SCM_IM_QUOTE)): |
| 2375 | return unmemoize_quote (expr, env); |
| 2376 | |
| 2377 | case (ISYMNUM (SCM_IM_SET_X)): |
| 2378 | return unmemoize_set_x (expr, env); |
| 2379 | |
| 2380 | case (ISYMNUM (SCM_IM_APPLY)): |
| 2381 | return unmemoize_apply (expr, env); |
| 2382 | |
| 2383 | case (ISYMNUM (SCM_IM_BIND)): |
| 2384 | return unmemoize_exprs (expr, env); /* FIXME */ |
| 2385 | |
| 2386 | case (ISYMNUM (SCM_IM_CONT)): |
| 2387 | return unmemoize_atcall_cc (expr, env); |
| 2388 | |
| 2389 | case (ISYMNUM (SCM_IM_CALL_WITH_VALUES)): |
| 2390 | return unmemoize_at_call_with_values (expr, env); |
| 2391 | |
| 2392 | #if 0 |
| 2393 | /* See futures.h for a comment why futures are not enabled. |
| 2394 | */ |
| 2395 | case (ISYMNUM (SCM_IM_FUTURE)): |
| 2396 | return unmemoize_future (expr, env); |
| 2397 | #endif |
| 2398 | |
| 2399 | case (ISYMNUM (SCM_IM_SLOT_REF)): |
| 2400 | return unmemoize_atslot_ref (expr, env); |
| 2401 | |
| 2402 | case (ISYMNUM (SCM_IM_SLOT_SET_X)): |
| 2403 | return unmemoize_atslot_set_x (expr, env); |
| 2404 | |
| 2405 | case (ISYMNUM (SCM_IM_NIL_COND)): |
| 2406 | return unmemoize_exprs (expr, env); /* FIXME */ |
| 2407 | |
| 2408 | default: |
| 2409 | return unmemoize_exprs (expr, env); /* FIXME */ |
| 2410 | } |
| 2411 | } |
| 2412 | |
| 2413 | |
| 2414 | /* scm_i_unmemocopy_expr and scm_i_unmemocopy_body take a memoized expression |
| 2415 | * respectively a memoized body together with its environment and rewrite it |
| 2416 | * to its original form. Thus, these functions are the inversion of the |
| 2417 | * rewrite rules above. The procedure is not optimized for speed. It's used |
| 2418 | * in scm_i_unmemoize_expr, scm_procedure_source, macro_print and scm_iprin1. |
| 2419 | * |
| 2420 | * Unmemoizing is not a reliable process. You cannot in general expect to get |
| 2421 | * the original source back. |
| 2422 | * |
| 2423 | * However, GOOPS currently relies on this for method compilation. This ought |
| 2424 | * to change. */ |
| 2425 | |
| 2426 | SCM |
| 2427 | scm_i_unmemocopy_expr (SCM expr, SCM env) |
| 2428 | { |
| 2429 | const SCM source_properties = scm_whash_lookup (scm_source_whash, expr); |
| 2430 | const SCM um_expr = unmemoize_expression (expr, env); |
| 2431 | |
| 2432 | if (scm_is_true (source_properties)) |
| 2433 | scm_whash_insert (scm_source_whash, um_expr, source_properties); |
| 2434 | |
| 2435 | return um_expr; |
| 2436 | } |
| 2437 | |
| 2438 | SCM |
| 2439 | scm_i_unmemocopy_body (SCM forms, SCM env) |
| 2440 | { |
| 2441 | const SCM source_properties = scm_whash_lookup (scm_source_whash, forms); |
| 2442 | const SCM um_forms = unmemoize_exprs (forms, env); |
| 2443 | |
| 2444 | if (scm_is_true (source_properties)) |
| 2445 | scm_whash_insert (scm_source_whash, um_forms, source_properties); |
| 2446 | |
| 2447 | return um_forms; |
| 2448 | } |
| 2449 | |
| 2450 | |
| 2451 | #if (SCM_ENABLE_DEPRECATED == 1) |
| 2452 | |
| 2453 | /* Deprecated in guile 1.7.0 on 2003-11-09. */ |
| 2454 | SCM |
| 2455 | scm_m_expand_body (SCM exprs, SCM env) |
| 2456 | { |
| 2457 | scm_c_issue_deprecation_warning |
| 2458 | ("`scm_m_expand_body' is deprecated."); |
| 2459 | m_expand_body (exprs, env); |
| 2460 | return exprs; |
| 2461 | } |
| 2462 | |
| 2463 | |
| 2464 | SCM_SYNTAX (s_undefine, "undefine", scm_makacro, scm_m_undefine); |
| 2465 | |
| 2466 | SCM |
| 2467 | scm_m_undefine (SCM expr, SCM env) |
| 2468 | { |
| 2469 | SCM variable; |
| 2470 | SCM location; |
| 2471 | |
| 2472 | const SCM cdr_expr = SCM_CDR (expr); |
| 2473 | ASSERT_SYNTAX (SCM_TOP_LEVEL (env), "Bad undefine placement in", expr); |
| 2474 | ASSERT_SYNTAX (scm_ilength (cdr_expr) >= 0, s_bad_expression, expr); |
| 2475 | ASSERT_SYNTAX (scm_ilength (cdr_expr) == 1, s_expression, expr); |
| 2476 | |
| 2477 | scm_c_issue_deprecation_warning |
| 2478 | ("`undefine' is deprecated.\n"); |
| 2479 | |
| 2480 | variable = SCM_CAR (cdr_expr); |
| 2481 | ASSERT_SYNTAX_2 (scm_is_symbol (variable), s_bad_variable, variable, expr); |
| 2482 | location = scm_sym2var (variable, scm_env_top_level (env), SCM_BOOL_F); |
| 2483 | ASSERT_SYNTAX_2 (scm_is_true (location) |
| 2484 | && !SCM_UNBNDP (SCM_VARIABLE_REF (location)), |
| 2485 | "variable already unbound ", variable, expr); |
| 2486 | SCM_VARIABLE_SET (location, SCM_UNDEFINED); |
| 2487 | return SCM_UNSPECIFIED; |
| 2488 | } |
| 2489 | |
| 2490 | SCM |
| 2491 | scm_macroexp (SCM x, SCM env) |
| 2492 | { |
| 2493 | scm_c_issue_deprecation_warning |
| 2494 | ("`scm_macroexp' is deprecated."); |
| 2495 | return macroexp (x, env); |
| 2496 | } |
| 2497 | |
| 2498 | #endif |
| 2499 | |
| 2500 | |
| 2501 | #if (SCM_ENABLE_DEPRECATED == 1) |
| 2502 | |
| 2503 | SCM |
| 2504 | scm_unmemocar (SCM form, SCM env) |
| 2505 | { |
| 2506 | scm_c_issue_deprecation_warning |
| 2507 | ("`scm_unmemocar' is deprecated."); |
| 2508 | |
| 2509 | if (!scm_is_pair (form)) |
| 2510 | return form; |
| 2511 | else |
| 2512 | { |
| 2513 | SCM c = SCM_CAR (form); |
| 2514 | if (SCM_VARIABLEP (c)) |
| 2515 | { |
| 2516 | SCM sym = scm_module_reverse_lookup (scm_env_module (env), c); |
| 2517 | if (scm_is_false (sym)) |
| 2518 | sym = sym_three_question_marks; |
| 2519 | SCM_SETCAR (form, sym); |
| 2520 | } |
| 2521 | else if (SCM_ILOCP (c)) |
| 2522 | { |
| 2523 | unsigned long int ir; |
| 2524 | |
| 2525 | for (ir = SCM_IFRAME (c); ir != 0; --ir) |
| 2526 | env = SCM_CDR (env); |
| 2527 | env = SCM_CAAR (env); |
| 2528 | for (ir = SCM_IDIST (c); ir != 0; --ir) |
| 2529 | env = SCM_CDR (env); |
| 2530 | |
| 2531 | SCM_SETCAR (form, SCM_ICDRP (c) ? env : SCM_CAR (env)); |
| 2532 | } |
| 2533 | return form; |
| 2534 | } |
| 2535 | } |
| 2536 | |
| 2537 | #endif |
| 2538 | |
| 2539 | /*****************************************************************************/ |
| 2540 | /*****************************************************************************/ |
| 2541 | /* The definitions for execution start here. */ |
| 2542 | /*****************************************************************************/ |
| 2543 | /*****************************************************************************/ |
| 2544 | |
| 2545 | SCM_GLOBAL_SYMBOL (scm_sym_enter_frame, "enter-frame"); |
| 2546 | SCM_GLOBAL_SYMBOL (scm_sym_apply_frame, "apply-frame"); |
| 2547 | SCM_GLOBAL_SYMBOL (scm_sym_exit_frame, "exit-frame"); |
| 2548 | SCM_GLOBAL_SYMBOL (scm_sym_memoize_symbol, "memoize-symbol"); |
| 2549 | SCM_GLOBAL_SYMBOL (scm_sym_trace, "trace"); |
| 2550 | SCM_SYMBOL (sym_instead, "instead"); |
| 2551 | |
| 2552 | /* A function object to implement "apply" for non-closure functions. */ |
| 2553 | static SCM f_apply; |
| 2554 | /* An endless list consisting of #<undefined> objects: */ |
| 2555 | static SCM undefineds; |
| 2556 | |
| 2557 | |
| 2558 | int |
| 2559 | scm_badargsp (SCM formals, SCM args) |
| 2560 | { |
| 2561 | while (!scm_is_null (formals)) |
| 2562 | { |
| 2563 | if (!scm_is_pair (formals)) |
| 2564 | return 0; |
| 2565 | if (scm_is_null (args)) |
| 2566 | return 1; |
| 2567 | formals = SCM_CDR (formals); |
| 2568 | args = SCM_CDR (args); |
| 2569 | } |
| 2570 | return !scm_is_null (args) ? 1 : 0; |
| 2571 | } |
| 2572 | |
| 2573 | \f |
| 2574 | |
| 2575 | /* The evaluator contains a plethora of EVAL symbols. |
| 2576 | * |
| 2577 | * |
| 2578 | * SCM_I_EVALIM is used when it is known that the expression is an |
| 2579 | * immediate. (This macro never calls an evaluator.) |
| 2580 | * |
| 2581 | * SCM_I_XEVAL evaluates an expression that is expected to have its symbols already |
| 2582 | * memoized. Expressions that are not of the form '(<form> <form> ...)' are |
| 2583 | * evaluated inline without calling an evaluator. |
| 2584 | * |
| 2585 | * This macro uses ceval or deval depending on its 3rd argument. |
| 2586 | * |
| 2587 | * SCM_I_XEVALCAR evaluates the car of an expression 'X:(Y:<form> <form> ...)', |
| 2588 | * potentially replacing a symbol at the position Y:<form> by its memoized |
| 2589 | * variable. If Y:<form> is not of the form '(<form> <form> ...)', the |
| 2590 | * evaluation is performed inline without calling an evaluator. |
| 2591 | * |
| 2592 | * This macro uses ceval or deval depending on its 3rd argument. |
| 2593 | * |
| 2594 | */ |
| 2595 | |
| 2596 | #define SCM_I_EVALIM2(x) \ |
| 2597 | ((scm_is_eq ((x), SCM_EOL) \ |
| 2598 | ? syntax_error (s_empty_combination, (x), SCM_UNDEFINED), 0 \ |
| 2599 | : 0), \ |
| 2600 | (x)) |
| 2601 | |
| 2602 | #define SCM_I_EVALIM(x, env) (SCM_ILOCP (x) \ |
| 2603 | ? *scm_ilookup ((x), (env)) \ |
| 2604 | : SCM_I_EVALIM2(x)) |
| 2605 | |
| 2606 | #define SCM_I_XEVAL(x, env, debug_p) \ |
| 2607 | (SCM_IMP (x) \ |
| 2608 | ? SCM_I_EVALIM2 (x) \ |
| 2609 | : (SCM_VARIABLEP (x) \ |
| 2610 | ? SCM_VARIABLE_REF (x) \ |
| 2611 | : (scm_is_pair (x) \ |
| 2612 | ? (debug_p \ |
| 2613 | ? deval ((x), (env)) \ |
| 2614 | : ceval ((x), (env))) \ |
| 2615 | : (x)))) |
| 2616 | |
| 2617 | #define SCM_I_XEVALCAR(x, env, debug_p) \ |
| 2618 | (SCM_IMP (SCM_CAR (x)) \ |
| 2619 | ? SCM_I_EVALIM (SCM_CAR (x), (env)) \ |
| 2620 | : (SCM_VARIABLEP (SCM_CAR (x)) \ |
| 2621 | ? SCM_VARIABLE_REF (SCM_CAR (x)) \ |
| 2622 | : (scm_is_pair (SCM_CAR (x)) \ |
| 2623 | ? (debug_p \ |
| 2624 | ? deval (SCM_CAR (x), (env)) \ |
| 2625 | : ceval (SCM_CAR (x), (env))) \ |
| 2626 | : (!scm_is_symbol (SCM_CAR (x)) \ |
| 2627 | ? SCM_CAR (x) \ |
| 2628 | : *scm_lookupcar ((x), (env), 1))))) |
| 2629 | |
| 2630 | scm_i_pthread_mutex_t source_mutex; |
| 2631 | |
| 2632 | |
| 2633 | /* Lookup a given local variable in an environment. The local variable is |
| 2634 | * given as an iloc, that is a triple <frame, binding, last?>, where frame |
| 2635 | * indicates the relative number of the environment frame (counting upwards |
| 2636 | * from the innermost environment frame), binding indicates the number of the |
| 2637 | * binding within the frame, and last? (which is extracted from the iloc using |
| 2638 | * the macro SCM_ICDRP) indicates whether the binding forms the binding at the |
| 2639 | * very end of the improper list of bindings. */ |
| 2640 | SCM * |
| 2641 | scm_ilookup (SCM iloc, SCM env) |
| 2642 | { |
| 2643 | unsigned int frame_nr = SCM_IFRAME (iloc); |
| 2644 | unsigned int binding_nr = SCM_IDIST (iloc); |
| 2645 | SCM frames = env; |
| 2646 | SCM bindings; |
| 2647 | |
| 2648 | for (; 0 != frame_nr; --frame_nr) |
| 2649 | frames = SCM_CDR (frames); |
| 2650 | |
| 2651 | bindings = SCM_CAR (frames); |
| 2652 | for (; 0 != binding_nr; --binding_nr) |
| 2653 | bindings = SCM_CDR (bindings); |
| 2654 | |
| 2655 | if (SCM_ICDRP (iloc)) |
| 2656 | return SCM_CDRLOC (bindings); |
| 2657 | return SCM_CARLOC (SCM_CDR (bindings)); |
| 2658 | } |
| 2659 | |
| 2660 | |
| 2661 | SCM_SYMBOL (scm_unbound_variable_key, "unbound-variable"); |
| 2662 | |
| 2663 | static void error_unbound_variable (SCM symbol) SCM_NORETURN; |
| 2664 | static void error_defined_variable (SCM symbol) SCM_NORETURN; |
| 2665 | |
| 2666 | /* Call this for variables that are unfound. |
| 2667 | */ |
| 2668 | static void |
| 2669 | error_unbound_variable (SCM symbol) |
| 2670 | { |
| 2671 | scm_error (scm_unbound_variable_key, NULL, |
| 2672 | "Unbound variable: ~S", |
| 2673 | scm_list_1 (symbol), SCM_BOOL_F); |
| 2674 | } |
| 2675 | |
| 2676 | /* Call this for variables that are found but contain SCM_UNDEFINED. |
| 2677 | */ |
| 2678 | static void |
| 2679 | error_defined_variable (SCM symbol) |
| 2680 | { |
| 2681 | /* We use the 'unbound-variable' key here as well, since it |
| 2682 | basically is the same kind of error, with a slight variation in |
| 2683 | the displayed message. |
| 2684 | */ |
| 2685 | scm_error (scm_unbound_variable_key, NULL, |
| 2686 | "Variable used before given a value: ~S", |
| 2687 | scm_list_1 (symbol), SCM_BOOL_F); |
| 2688 | } |
| 2689 | |
| 2690 | |
| 2691 | /* The Lookup Car Race |
| 2692 | - by Eva Luator |
| 2693 | |
| 2694 | Memoization of variables and special forms is done while executing |
| 2695 | the code for the first time. As long as there is only one thread |
| 2696 | everything is fine, but as soon as two threads execute the same |
| 2697 | code concurrently `for the first time' they can come into conflict. |
| 2698 | |
| 2699 | This memoization includes rewriting variable references into more |
| 2700 | efficient forms and expanding macros. Furthermore, macro expansion |
| 2701 | includes `compiling' special forms like `let', `cond', etc. into |
| 2702 | tree-code instructions. |
| 2703 | |
| 2704 | There shouldn't normally be a problem with memoizing local and |
| 2705 | global variable references (into ilocs and variables), because all |
| 2706 | threads will mutate the code in *exactly* the same way and (if I |
| 2707 | read the C code correctly) it is not possible to observe a half-way |
| 2708 | mutated cons cell. The lookup procedure can handle this |
| 2709 | transparently without any critical sections. |
| 2710 | |
| 2711 | It is different with macro expansion, because macro expansion |
| 2712 | happens outside of the lookup procedure and can't be |
| 2713 | undone. Therefore the lookup procedure can't cope with it. It has |
| 2714 | to indicate failure when it detects a lost race and hope that the |
| 2715 | caller can handle it. Luckily, it turns out that this is the case. |
| 2716 | |
| 2717 | An example to illustrate this: Suppose that the following form will |
| 2718 | be memoized concurrently by two threads |
| 2719 | |
| 2720 | (let ((x 12)) x) |
| 2721 | |
| 2722 | Let's first examine the lookup of X in the body. The first thread |
| 2723 | decides that it has to find the symbol "x" in the environment and |
| 2724 | starts to scan it. Then the other thread takes over and actually |
| 2725 | overtakes the first. It looks up "x" and substitutes an |
| 2726 | appropriate iloc for it. Now the first thread continues and |
| 2727 | completes its lookup. It comes to exactly the same conclusions as |
| 2728 | the second one and could - without much ado - just overwrite the |
| 2729 | iloc with the same iloc. |
| 2730 | |
| 2731 | But let's see what will happen when the race occurs while looking |
| 2732 | up the symbol "let" at the start of the form. It could happen that |
| 2733 | the second thread interrupts the lookup of the first thread and not |
| 2734 | only substitutes a variable for it but goes right ahead and |
| 2735 | replaces it with the compiled form (#@let* (x 12) x). Now, when |
| 2736 | the first thread completes its lookup, it would replace the #@let* |
| 2737 | with a variable containing the "let" binding, effectively reverting |
| 2738 | the form to (let (x 12) x). This is wrong. It has to detect that |
| 2739 | it has lost the race and the evaluator has to reconsider the |
| 2740 | changed form completely. |
| 2741 | |
| 2742 | This race condition could be resolved with some kind of traffic |
| 2743 | light (like mutexes) around scm_lookupcar, but I think that it is |
| 2744 | best to avoid them in this case. They would serialize memoization |
| 2745 | completely and because lookup involves calling arbitrary Scheme |
| 2746 | code (via the lookup-thunk), threads could be blocked for an |
| 2747 | arbitrary amount of time or even deadlock. But with the current |
| 2748 | solution a lot of unnecessary work is potentially done. */ |
| 2749 | |
| 2750 | /* SCM_LOOKUPCAR1 is what SCM_LOOKUPCAR used to be but is allowed to |
| 2751 | return NULL to indicate a failed lookup due to some race conditions |
| 2752 | between threads. This only happens when VLOC is the first cell of |
| 2753 | a special form that will eventually be memoized (like `let', etc.) |
| 2754 | In that case the whole lookup is bogus and the caller has to |
| 2755 | reconsider the complete special form. |
| 2756 | |
| 2757 | SCM_LOOKUPCAR is still there, of course. It just calls |
| 2758 | SCM_LOOKUPCAR1 and aborts on receiving NULL. So SCM_LOOKUPCAR |
| 2759 | should only be called when it is known that VLOC is not the first |
| 2760 | pair of a special form. Otherwise, use SCM_LOOKUPCAR1 and check |
| 2761 | for NULL. I think I've found the only places where this |
| 2762 | applies. */ |
| 2763 | |
| 2764 | static SCM * |
| 2765 | scm_lookupcar1 (SCM vloc, SCM genv, int check) |
| 2766 | { |
| 2767 | SCM env = genv; |
| 2768 | register SCM *al, fl, var = SCM_CAR (vloc); |
| 2769 | register SCM iloc = SCM_ILOC00; |
| 2770 | for (; SCM_NIMP (env); env = SCM_CDR (env)) |
| 2771 | { |
| 2772 | if (!scm_is_pair (SCM_CAR (env))) |
| 2773 | break; |
| 2774 | al = SCM_CARLOC (env); |
| 2775 | for (fl = SCM_CAR (*al); SCM_NIMP (fl); fl = SCM_CDR (fl)) |
| 2776 | { |
| 2777 | if (!scm_is_pair (fl)) |
| 2778 | { |
| 2779 | if (scm_is_eq (fl, var)) |
| 2780 | { |
| 2781 | if (!scm_is_eq (SCM_CAR (vloc), var)) |
| 2782 | goto race; |
| 2783 | SCM_SET_CELL_WORD_0 (vloc, SCM_UNPACK (iloc) + SCM_ICDR); |
| 2784 | return SCM_CDRLOC (*al); |
| 2785 | } |
| 2786 | else |
| 2787 | break; |
| 2788 | } |
| 2789 | al = SCM_CDRLOC (*al); |
| 2790 | if (scm_is_eq (SCM_CAR (fl), var)) |
| 2791 | { |
| 2792 | if (SCM_UNBNDP (SCM_CAR (*al))) |
| 2793 | error_defined_variable (var); |
| 2794 | if (!scm_is_eq (SCM_CAR (vloc), var)) |
| 2795 | goto race; |
| 2796 | SCM_SETCAR (vloc, iloc); |
| 2797 | return SCM_CARLOC (*al); |
| 2798 | } |
| 2799 | iloc = SCM_PACK (SCM_UNPACK (iloc) + SCM_IDINC); |
| 2800 | } |
| 2801 | iloc = SCM_PACK ((~SCM_IDSTMSK) & (SCM_UNPACK(iloc) + SCM_IFRINC)); |
| 2802 | } |
| 2803 | { |
| 2804 | SCM top_thunk, real_var; |
| 2805 | if (SCM_NIMP (env)) |
| 2806 | { |
| 2807 | top_thunk = SCM_CAR (env); /* env now refers to a |
| 2808 | top level env thunk */ |
| 2809 | env = SCM_CDR (env); |
| 2810 | } |
| 2811 | else |
| 2812 | top_thunk = SCM_BOOL_F; |
| 2813 | real_var = scm_sym2var (var, top_thunk, SCM_BOOL_F); |
| 2814 | if (scm_is_false (real_var)) |
| 2815 | goto errout; |
| 2816 | |
| 2817 | if (!scm_is_null (env) || SCM_UNBNDP (SCM_VARIABLE_REF (real_var))) |
| 2818 | { |
| 2819 | errout: |
| 2820 | if (check) |
| 2821 | { |
| 2822 | if (scm_is_null (env)) |
| 2823 | error_unbound_variable (var); |
| 2824 | else |
| 2825 | scm_misc_error (NULL, "Damaged environment: ~S", |
| 2826 | scm_list_1 (var)); |
| 2827 | } |
| 2828 | else |
| 2829 | { |
| 2830 | /* A variable could not be found, but we shall |
| 2831 | not throw an error. */ |
| 2832 | static SCM undef_object = SCM_UNDEFINED; |
| 2833 | return &undef_object; |
| 2834 | } |
| 2835 | } |
| 2836 | |
| 2837 | if (!scm_is_eq (SCM_CAR (vloc), var)) |
| 2838 | { |
| 2839 | /* Some other thread has changed the very cell we are working |
| 2840 | on. In effect, it must have done our job or messed it up |
| 2841 | completely. */ |
| 2842 | race: |
| 2843 | var = SCM_CAR (vloc); |
| 2844 | if (SCM_VARIABLEP (var)) |
| 2845 | return SCM_VARIABLE_LOC (var); |
| 2846 | if (SCM_ILOCP (var)) |
| 2847 | return scm_ilookup (var, genv); |
| 2848 | /* We can't cope with anything else than variables and ilocs. When |
| 2849 | a special form has been memoized (i.e. `let' into `#@let') we |
| 2850 | return NULL and expect the calling function to do the right |
| 2851 | thing. For the evaluator, this means going back and redoing |
| 2852 | the dispatch on the car of the form. */ |
| 2853 | return NULL; |
| 2854 | } |
| 2855 | |
| 2856 | SCM_SETCAR (vloc, real_var); |
| 2857 | return SCM_VARIABLE_LOC (real_var); |
| 2858 | } |
| 2859 | } |
| 2860 | |
| 2861 | SCM * |
| 2862 | scm_lookupcar (SCM vloc, SCM genv, int check) |
| 2863 | { |
| 2864 | SCM *loc = scm_lookupcar1 (vloc, genv, check); |
| 2865 | if (loc == NULL) |
| 2866 | abort (); |
| 2867 | return loc; |
| 2868 | } |
| 2869 | |
| 2870 | |
| 2871 | /* During execution, look up a symbol in the top level of the given local |
| 2872 | * environment and return the corresponding variable object. If no binding |
| 2873 | * for the symbol can be found, an 'Unbound variable' error is signalled. */ |
| 2874 | static SCM |
| 2875 | lazy_memoize_variable (const SCM symbol, const SCM environment) |
| 2876 | { |
| 2877 | const SCM top_level = scm_env_top_level (environment); |
| 2878 | const SCM variable = scm_sym2var (symbol, top_level, SCM_BOOL_F); |
| 2879 | |
| 2880 | if (scm_is_false (variable)) |
| 2881 | error_unbound_variable (symbol); |
| 2882 | else |
| 2883 | return variable; |
| 2884 | } |
| 2885 | |
| 2886 | |
| 2887 | SCM |
| 2888 | scm_eval_car (SCM pair, SCM env) |
| 2889 | { |
| 2890 | return SCM_I_XEVALCAR (pair, env, scm_debug_mode_p); |
| 2891 | } |
| 2892 | |
| 2893 | |
| 2894 | SCM |
| 2895 | scm_eval_body (SCM code, SCM env) |
| 2896 | { |
| 2897 | SCM next; |
| 2898 | |
| 2899 | again: |
| 2900 | next = SCM_CDR (code); |
| 2901 | while (!scm_is_null (next)) |
| 2902 | { |
| 2903 | if (SCM_IMP (SCM_CAR (code))) |
| 2904 | { |
| 2905 | if (SCM_ISYMP (SCM_CAR (code))) |
| 2906 | { |
| 2907 | scm_dynwind_begin (0); |
| 2908 | scm_i_dynwind_pthread_mutex_lock (&source_mutex); |
| 2909 | /* check for race condition */ |
| 2910 | if (SCM_ISYMP (SCM_CAR (code))) |
| 2911 | m_expand_body (code, env); |
| 2912 | scm_dynwind_end (); |
| 2913 | goto again; |
| 2914 | } |
| 2915 | } |
| 2916 | else |
| 2917 | SCM_I_XEVAL (SCM_CAR (code), env, scm_debug_mode_p); |
| 2918 | code = next; |
| 2919 | next = SCM_CDR (code); |
| 2920 | } |
| 2921 | return SCM_I_XEVALCAR (code, env, scm_debug_mode_p); |
| 2922 | } |
| 2923 | |
| 2924 | |
| 2925 | /* scm_last_debug_frame contains a pointer to the last debugging information |
| 2926 | * stack frame. It is accessed very often from the debugging evaluator, so it |
| 2927 | * should probably not be indirectly addressed. Better to save and restore it |
| 2928 | * from the current root at any stack swaps. |
| 2929 | */ |
| 2930 | |
| 2931 | /* scm_debug_eframe_size is the number of slots available for pseudo |
| 2932 | * stack frames at each real stack frame. |
| 2933 | */ |
| 2934 | |
| 2935 | long scm_debug_eframe_size; |
| 2936 | |
| 2937 | int scm_debug_mode_p; |
| 2938 | int scm_check_entry_p; |
| 2939 | int scm_check_apply_p; |
| 2940 | int scm_check_exit_p; |
| 2941 | int scm_check_memoize_p; |
| 2942 | |
| 2943 | long scm_eval_stack; |
| 2944 | |
| 2945 | scm_t_option scm_eval_opts[] = { |
| 2946 | { SCM_OPTION_INTEGER, "stack", 22000, "Size of thread stacks (in machine words)." }, |
| 2947 | { 0 } |
| 2948 | }; |
| 2949 | |
| 2950 | scm_t_option scm_debug_opts[] = { |
| 2951 | { SCM_OPTION_BOOLEAN, "cheap", 1, |
| 2952 | "*This option is now obsolete. Setting it has no effect." }, |
| 2953 | { SCM_OPTION_BOOLEAN, "breakpoints", 0, "*Check for breakpoints." }, |
| 2954 | { SCM_OPTION_BOOLEAN, "trace", 0, "*Trace mode." }, |
| 2955 | { SCM_OPTION_BOOLEAN, "procnames", 1, |
| 2956 | "Record procedure names at definition." }, |
| 2957 | { SCM_OPTION_BOOLEAN, "backwards", 0, |
| 2958 | "Display backtrace in anti-chronological order." }, |
| 2959 | { SCM_OPTION_INTEGER, "width", 79, "Maximal width of backtrace." }, |
| 2960 | { SCM_OPTION_INTEGER, "indent", 10, "Maximal indentation in backtrace." }, |
| 2961 | { SCM_OPTION_INTEGER, "frames", 3, |
| 2962 | "Maximum number of tail-recursive frames in backtrace." }, |
| 2963 | { SCM_OPTION_INTEGER, "maxdepth", 1000, |
| 2964 | "Maximal number of stored backtrace frames." }, |
| 2965 | { SCM_OPTION_INTEGER, "depth", 20, "Maximal length of printed backtrace." }, |
| 2966 | { SCM_OPTION_BOOLEAN, "backtrace", 0, "Show backtrace on error." }, |
| 2967 | { SCM_OPTION_BOOLEAN, "debug", 0, "Use the debugging evaluator." }, |
| 2968 | |
| 2969 | { SCM_OPTION_INTEGER, "stack", 20000, "Stack size limit (measured in words; 0 = no check)." }, |
| 2970 | { SCM_OPTION_SCM, "show-file-name", (unsigned long)SCM_BOOL_T, |
| 2971 | "Show file names and line numbers " |
| 2972 | "in backtraces when not `#f'. A value of `base' " |
| 2973 | "displays only base names, while `#t' displays full names."}, |
| 2974 | { SCM_OPTION_BOOLEAN, "warn-deprecated", 0, |
| 2975 | "Warn when deprecated features are used." }, |
| 2976 | { 0 }, |
| 2977 | }; |
| 2978 | |
| 2979 | |
| 2980 | /* |
| 2981 | * this ordering is awkward and illogical, but we maintain it for |
| 2982 | * compatibility. --hwn |
| 2983 | */ |
| 2984 | scm_t_option scm_evaluator_trap_table[] = { |
| 2985 | { SCM_OPTION_BOOLEAN, "traps", 0, "Enable evaluator traps." }, |
| 2986 | { SCM_OPTION_BOOLEAN, "enter-frame", 0, "Trap when eval enters new frame." }, |
| 2987 | { SCM_OPTION_BOOLEAN, "apply-frame", 0, "Trap when entering apply." }, |
| 2988 | { SCM_OPTION_BOOLEAN, "exit-frame", 0, "Trap when exiting eval or apply." }, |
| 2989 | { SCM_OPTION_SCM, "enter-frame-handler", (unsigned long)SCM_BOOL_F, "Handler for enter-frame traps." }, |
| 2990 | { SCM_OPTION_SCM, "apply-frame-handler", (unsigned long)SCM_BOOL_F, "Handler for apply-frame traps." }, |
| 2991 | { SCM_OPTION_SCM, "exit-frame-handler", (unsigned long)SCM_BOOL_F, "Handler for exit-frame traps." }, |
| 2992 | { SCM_OPTION_BOOLEAN, "memoize-symbol", 0, "Trap when memoizing a symbol." }, |
| 2993 | { SCM_OPTION_SCM, "memoize-symbol-handler", (unsigned long)SCM_BOOL_F, "The handler for memoization." }, |
| 2994 | { 0 } |
| 2995 | }; |
| 2996 | |
| 2997 | |
| 2998 | SCM_DEFINE (scm_eval_options_interface, "eval-options-interface", 0, 1, 0, |
| 2999 | (SCM setting), |
| 3000 | "Option interface for the evaluation options. Instead of using\n" |
| 3001 | "this procedure directly, use the procedures @code{eval-enable},\n" |
| 3002 | "@code{eval-disable}, @code{eval-set!} and @code{eval-options}.") |
| 3003 | #define FUNC_NAME s_scm_eval_options_interface |
| 3004 | { |
| 3005 | SCM ans; |
| 3006 | |
| 3007 | scm_dynwind_begin (0); |
| 3008 | scm_dynwind_critical_section (SCM_BOOL_F); |
| 3009 | ans = scm_options (setting, |
| 3010 | scm_eval_opts, |
| 3011 | FUNC_NAME); |
| 3012 | scm_eval_stack = SCM_EVAL_STACK * sizeof (void *); |
| 3013 | scm_dynwind_end (); |
| 3014 | |
| 3015 | return ans; |
| 3016 | } |
| 3017 | #undef FUNC_NAME |
| 3018 | |
| 3019 | |
| 3020 | SCM_DEFINE (scm_evaluator_traps, "evaluator-traps-interface", 0, 1, 0, |
| 3021 | (SCM setting), |
| 3022 | "Option interface for the evaluator trap options.") |
| 3023 | #define FUNC_NAME s_scm_evaluator_traps |
| 3024 | { |
| 3025 | SCM ans; |
| 3026 | |
| 3027 | |
| 3028 | scm_options_try (setting, |
| 3029 | scm_evaluator_trap_table, |
| 3030 | FUNC_NAME, 1); |
| 3031 | SCM_CRITICAL_SECTION_START; |
| 3032 | ans = scm_options (setting, |
| 3033 | scm_evaluator_trap_table, |
| 3034 | FUNC_NAME); |
| 3035 | |
| 3036 | /* njrev: same again. */ |
| 3037 | SCM_RESET_DEBUG_MODE; |
| 3038 | SCM_CRITICAL_SECTION_END; |
| 3039 | return ans; |
| 3040 | } |
| 3041 | #undef FUNC_NAME |
| 3042 | |
| 3043 | |
| 3044 | |
| 3045 | \f |
| 3046 | |
| 3047 | /* Simple procedure calls |
| 3048 | */ |
| 3049 | |
| 3050 | SCM |
| 3051 | scm_call_0 (SCM proc) |
| 3052 | { |
| 3053 | return scm_apply (proc, SCM_EOL, SCM_EOL); |
| 3054 | } |
| 3055 | |
| 3056 | SCM |
| 3057 | scm_call_1 (SCM proc, SCM arg1) |
| 3058 | { |
| 3059 | return scm_apply (proc, arg1, scm_listofnull); |
| 3060 | } |
| 3061 | |
| 3062 | SCM |
| 3063 | scm_call_2 (SCM proc, SCM arg1, SCM arg2) |
| 3064 | { |
| 3065 | return scm_apply (proc, arg1, scm_cons (arg2, scm_listofnull)); |
| 3066 | } |
| 3067 | |
| 3068 | SCM |
| 3069 | scm_call_3 (SCM proc, SCM arg1, SCM arg2, SCM arg3) |
| 3070 | { |
| 3071 | return scm_apply (proc, arg1, scm_cons2 (arg2, arg3, scm_listofnull)); |
| 3072 | } |
| 3073 | |
| 3074 | SCM |
| 3075 | scm_call_4 (SCM proc, SCM arg1, SCM arg2, SCM arg3, SCM arg4) |
| 3076 | { |
| 3077 | return scm_apply (proc, arg1, scm_cons2 (arg2, arg3, |
| 3078 | scm_cons (arg4, scm_listofnull))); |
| 3079 | } |
| 3080 | |
| 3081 | /* Simple procedure applies |
| 3082 | */ |
| 3083 | |
| 3084 | SCM |
| 3085 | scm_apply_0 (SCM proc, SCM args) |
| 3086 | { |
| 3087 | return scm_apply (proc, args, SCM_EOL); |
| 3088 | } |
| 3089 | |
| 3090 | SCM |
| 3091 | scm_apply_1 (SCM proc, SCM arg1, SCM args) |
| 3092 | { |
| 3093 | return scm_apply (proc, scm_cons (arg1, args), SCM_EOL); |
| 3094 | } |
| 3095 | |
| 3096 | SCM |
| 3097 | scm_apply_2 (SCM proc, SCM arg1, SCM arg2, SCM args) |
| 3098 | { |
| 3099 | return scm_apply (proc, scm_cons2 (arg1, arg2, args), SCM_EOL); |
| 3100 | } |
| 3101 | |
| 3102 | SCM |
| 3103 | scm_apply_3 (SCM proc, SCM arg1, SCM arg2, SCM arg3, SCM args) |
| 3104 | { |
| 3105 | return scm_apply (proc, scm_cons (arg1, scm_cons2 (arg2, arg3, args)), |
| 3106 | SCM_EOL); |
| 3107 | } |
| 3108 | |
| 3109 | /* This code processes the arguments to apply: |
| 3110 | |
| 3111 | (apply PROC ARG1 ... ARGS) |
| 3112 | |
| 3113 | Given a list (ARG1 ... ARGS), this function conses the ARG1 |
| 3114 | ... arguments onto the front of ARGS, and returns the resulting |
| 3115 | list. Note that ARGS is a list; thus, the argument to this |
| 3116 | function is a list whose last element is a list. |
| 3117 | |
| 3118 | Apply calls this function, and applies PROC to the elements of the |
| 3119 | result. apply:nconc2last takes care of building the list of |
| 3120 | arguments, given (ARG1 ... ARGS). |
| 3121 | |
| 3122 | Rather than do new consing, apply:nconc2last destroys its argument. |
| 3123 | On that topic, this code came into my care with the following |
| 3124 | beautifully cryptic comment on that topic: "This will only screw |
| 3125 | you if you do (scm_apply scm_apply '( ... ))" If you know what |
| 3126 | they're referring to, send me a patch to this comment. */ |
| 3127 | |
| 3128 | SCM_DEFINE (scm_nconc2last, "apply:nconc2last", 1, 0, 0, |
| 3129 | (SCM lst), |
| 3130 | "Given a list (@var{arg1} @dots{} @var{args}), this function\n" |
| 3131 | "conses the @var{arg1} @dots{} arguments onto the front of\n" |
| 3132 | "@var{args}, and returns the resulting list. Note that\n" |
| 3133 | "@var{args} is a list; thus, the argument to this function is\n" |
| 3134 | "a list whose last element is a list.\n" |
| 3135 | "Note: Rather than do new consing, @code{apply:nconc2last}\n" |
| 3136 | "destroys its argument, so use with care.") |
| 3137 | #define FUNC_NAME s_scm_nconc2last |
| 3138 | { |
| 3139 | SCM *lloc; |
| 3140 | SCM_VALIDATE_NONEMPTYLIST (1, lst); |
| 3141 | lloc = &lst; |
| 3142 | while (!scm_is_null (SCM_CDR (*lloc))) /* Perhaps should be |
| 3143 | SCM_NULL_OR_NIL_P, but not |
| 3144 | needed in 99.99% of cases, |
| 3145 | and it could seriously hurt |
| 3146 | performance. - Neil */ |
| 3147 | lloc = SCM_CDRLOC (*lloc); |
| 3148 | SCM_ASSERT (scm_ilength (SCM_CAR (*lloc)) >= 0, lst, SCM_ARG1, FUNC_NAME); |
| 3149 | *lloc = SCM_CAR (*lloc); |
| 3150 | return lst; |
| 3151 | } |
| 3152 | #undef FUNC_NAME |
| 3153 | |
| 3154 | |
| 3155 | |
| 3156 | /* SECTION: The rest of this file is only read once. |
| 3157 | */ |
| 3158 | |
| 3159 | /* Trampolines |
| 3160 | * |
| 3161 | * Trampolines make it possible to move procedure application dispatch |
| 3162 | * outside inner loops. The motivation was clean implementation of |
| 3163 | * efficient replacements of R5RS primitives in SRFI-1. |
| 3164 | * |
| 3165 | * The semantics is clear: scm_trampoline_N returns an optimized |
| 3166 | * version of scm_call_N (or NULL if the procedure isn't applicable |
| 3167 | * on N args). |
| 3168 | * |
| 3169 | * Applying the optimization to map and for-each increased efficiency |
| 3170 | * noticeably. For example, (map abs ls) is now 8 times faster than |
| 3171 | * before. |
| 3172 | */ |
| 3173 | |
| 3174 | static SCM |
| 3175 | call_subr0_0 (SCM proc) |
| 3176 | { |
| 3177 | return SCM_SUBRF (proc) (); |
| 3178 | } |
| 3179 | |
| 3180 | static SCM |
| 3181 | call_subr1o_0 (SCM proc) |
| 3182 | { |
| 3183 | return SCM_SUBRF (proc) (SCM_UNDEFINED); |
| 3184 | } |
| 3185 | |
| 3186 | static SCM |
| 3187 | call_lsubr_0 (SCM proc) |
| 3188 | { |
| 3189 | return SCM_SUBRF (proc) (SCM_EOL); |
| 3190 | } |
| 3191 | |
| 3192 | SCM |
| 3193 | scm_i_call_closure_0 (SCM proc) |
| 3194 | { |
| 3195 | const SCM env = SCM_EXTEND_ENV (SCM_CLOSURE_FORMALS (proc), |
| 3196 | SCM_EOL, |
| 3197 | SCM_ENV (proc)); |
| 3198 | const SCM result = scm_eval_body (SCM_CLOSURE_BODY (proc), env); |
| 3199 | return result; |
| 3200 | } |
| 3201 | |
| 3202 | scm_t_trampoline_0 |
| 3203 | scm_trampoline_0 (SCM proc) |
| 3204 | { |
| 3205 | scm_t_trampoline_0 trampoline; |
| 3206 | |
| 3207 | if (SCM_IMP (proc)) |
| 3208 | return NULL; |
| 3209 | |
| 3210 | switch (SCM_TYP7 (proc)) |
| 3211 | { |
| 3212 | case scm_tc7_subr_0: |
| 3213 | trampoline = call_subr0_0; |
| 3214 | break; |
| 3215 | case scm_tc7_subr_1o: |
| 3216 | trampoline = call_subr1o_0; |
| 3217 | break; |
| 3218 | case scm_tc7_lsubr: |
| 3219 | trampoline = call_lsubr_0; |
| 3220 | break; |
| 3221 | case scm_tcs_closures: |
| 3222 | { |
| 3223 | SCM formals = SCM_CLOSURE_FORMALS (proc); |
| 3224 | if (scm_is_null (formals) || !scm_is_pair (formals)) |
| 3225 | trampoline = scm_i_call_closure_0; |
| 3226 | else |
| 3227 | return NULL; |
| 3228 | break; |
| 3229 | } |
| 3230 | case scm_tcs_struct: |
| 3231 | if (SCM_OBJ_CLASS_FLAGS (proc) & SCM_CLASSF_PURE_GENERIC) |
| 3232 | trampoline = scm_call_generic_0; |
| 3233 | else if (SCM_I_OPERATORP (proc)) |
| 3234 | trampoline = scm_call_0; |
| 3235 | else |
| 3236 | return NULL; |
| 3237 | break; |
| 3238 | case scm_tc7_smob: |
| 3239 | if (SCM_SMOB_APPLICABLE_P (proc)) |
| 3240 | trampoline = SCM_SMOB_DESCRIPTOR (proc).apply_0; |
| 3241 | else |
| 3242 | return NULL; |
| 3243 | break; |
| 3244 | case scm_tc7_asubr: |
| 3245 | case scm_tc7_rpsubr: |
| 3246 | case scm_tc7_gsubr: |
| 3247 | case scm_tc7_pws: |
| 3248 | trampoline = scm_call_0; |
| 3249 | break; |
| 3250 | default: |
| 3251 | return NULL; /* not applicable on zero arguments */ |
| 3252 | } |
| 3253 | /* We only reach this point if a valid trampoline was determined. */ |
| 3254 | |
| 3255 | /* If debugging is enabled, we want to see all calls to proc on the stack. |
| 3256 | * Thus, we replace the trampoline shortcut with scm_call_0. */ |
| 3257 | if (scm_debug_mode_p) |
| 3258 | return scm_call_0; |
| 3259 | else |
| 3260 | return trampoline; |
| 3261 | } |
| 3262 | |
| 3263 | static SCM |
| 3264 | call_subr1_1 (SCM proc, SCM arg1) |
| 3265 | { |
| 3266 | return SCM_SUBRF (proc) (arg1); |
| 3267 | } |
| 3268 | |
| 3269 | static SCM |
| 3270 | call_subr2o_1 (SCM proc, SCM arg1) |
| 3271 | { |
| 3272 | return SCM_SUBRF (proc) (arg1, SCM_UNDEFINED); |
| 3273 | } |
| 3274 | |
| 3275 | static SCM |
| 3276 | call_lsubr_1 (SCM proc, SCM arg1) |
| 3277 | { |
| 3278 | return SCM_SUBRF (proc) (scm_list_1 (arg1)); |
| 3279 | } |
| 3280 | |
| 3281 | static SCM |
| 3282 | call_dsubr_1 (SCM proc, SCM arg1) |
| 3283 | { |
| 3284 | if (SCM_I_INUMP (arg1)) |
| 3285 | { |
| 3286 | return (scm_from_double (SCM_DSUBRF (proc) ((double) SCM_I_INUM (arg1)))); |
| 3287 | } |
| 3288 | else if (SCM_REALP (arg1)) |
| 3289 | { |
| 3290 | return (scm_from_double (SCM_DSUBRF (proc) (SCM_REAL_VALUE (arg1)))); |
| 3291 | } |
| 3292 | else if (SCM_BIGP (arg1)) |
| 3293 | { |
| 3294 | return (scm_from_double (SCM_DSUBRF (proc) (scm_i_big2dbl (arg1)))); |
| 3295 | } |
| 3296 | else if (SCM_FRACTIONP (arg1)) |
| 3297 | { |
| 3298 | return (scm_from_double (SCM_DSUBRF (proc) (scm_i_fraction2double (arg1)))); |
| 3299 | } |
| 3300 | SCM_WTA_DISPATCH_1 (*SCM_SUBR_GENERIC (proc), arg1, |
| 3301 | SCM_ARG1, scm_i_symbol_chars (SCM_SNAME (proc))); |
| 3302 | } |
| 3303 | |
| 3304 | static SCM |
| 3305 | call_cxr_1 (SCM proc, SCM arg1) |
| 3306 | { |
| 3307 | return scm_i_chase_pairs (arg1, (scm_t_bits) SCM_SUBRF (proc)); |
| 3308 | } |
| 3309 | |
| 3310 | static SCM |
| 3311 | call_closure_1 (SCM proc, SCM arg1) |
| 3312 | { |
| 3313 | const SCM env = SCM_EXTEND_ENV (SCM_CLOSURE_FORMALS (proc), |
| 3314 | scm_list_1 (arg1), |
| 3315 | SCM_ENV (proc)); |
| 3316 | const SCM result = scm_eval_body (SCM_CLOSURE_BODY (proc), env); |
| 3317 | return result; |
| 3318 | } |
| 3319 | |
| 3320 | scm_t_trampoline_1 |
| 3321 | scm_trampoline_1 (SCM proc) |
| 3322 | { |
| 3323 | scm_t_trampoline_1 trampoline; |
| 3324 | |
| 3325 | if (SCM_IMP (proc)) |
| 3326 | return NULL; |
| 3327 | |
| 3328 | switch (SCM_TYP7 (proc)) |
| 3329 | { |
| 3330 | case scm_tc7_subr_1: |
| 3331 | case scm_tc7_subr_1o: |
| 3332 | trampoline = call_subr1_1; |
| 3333 | break; |
| 3334 | case scm_tc7_subr_2o: |
| 3335 | trampoline = call_subr2o_1; |
| 3336 | break; |
| 3337 | case scm_tc7_lsubr: |
| 3338 | trampoline = call_lsubr_1; |
| 3339 | break; |
| 3340 | case scm_tc7_dsubr: |
| 3341 | trampoline = call_dsubr_1; |
| 3342 | break; |
| 3343 | case scm_tc7_cxr: |
| 3344 | trampoline = call_cxr_1; |
| 3345 | break; |
| 3346 | case scm_tcs_closures: |
| 3347 | { |
| 3348 | SCM formals = SCM_CLOSURE_FORMALS (proc); |
| 3349 | if (!scm_is_null (formals) |
| 3350 | && (!scm_is_pair (formals) || !scm_is_pair (SCM_CDR (formals)))) |
| 3351 | trampoline = call_closure_1; |
| 3352 | else |
| 3353 | return NULL; |
| 3354 | break; |
| 3355 | } |
| 3356 | case scm_tcs_struct: |
| 3357 | if (SCM_OBJ_CLASS_FLAGS (proc) & SCM_CLASSF_PURE_GENERIC) |
| 3358 | trampoline = scm_call_generic_1; |
| 3359 | else if (SCM_I_OPERATORP (proc)) |
| 3360 | trampoline = scm_call_1; |
| 3361 | else |
| 3362 | return NULL; |
| 3363 | break; |
| 3364 | case scm_tc7_smob: |
| 3365 | if (SCM_SMOB_APPLICABLE_P (proc)) |
| 3366 | trampoline = SCM_SMOB_DESCRIPTOR (proc).apply_1; |
| 3367 | else |
| 3368 | return NULL; |
| 3369 | break; |
| 3370 | case scm_tc7_asubr: |
| 3371 | case scm_tc7_rpsubr: |
| 3372 | case scm_tc7_gsubr: |
| 3373 | case scm_tc7_pws: |
| 3374 | trampoline = scm_call_1; |
| 3375 | break; |
| 3376 | default: |
| 3377 | return NULL; /* not applicable on one arg */ |
| 3378 | } |
| 3379 | /* We only reach this point if a valid trampoline was determined. */ |
| 3380 | |
| 3381 | /* If debugging is enabled, we want to see all calls to proc on the stack. |
| 3382 | * Thus, we replace the trampoline shortcut with scm_call_1. */ |
| 3383 | if (scm_debug_mode_p) |
| 3384 | return scm_call_1; |
| 3385 | else |
| 3386 | return trampoline; |
| 3387 | } |
| 3388 | |
| 3389 | static SCM |
| 3390 | call_subr2_2 (SCM proc, SCM arg1, SCM arg2) |
| 3391 | { |
| 3392 | return SCM_SUBRF (proc) (arg1, arg2); |
| 3393 | } |
| 3394 | |
| 3395 | static SCM |
| 3396 | call_lsubr2_2 (SCM proc, SCM arg1, SCM arg2) |
| 3397 | { |
| 3398 | return SCM_SUBRF (proc) (arg1, arg2, SCM_EOL); |
| 3399 | } |
| 3400 | |
| 3401 | static SCM |
| 3402 | call_lsubr_2 (SCM proc, SCM arg1, SCM arg2) |
| 3403 | { |
| 3404 | return SCM_SUBRF (proc) (scm_list_2 (arg1, arg2)); |
| 3405 | } |
| 3406 | |
| 3407 | static SCM |
| 3408 | call_closure_2 (SCM proc, SCM arg1, SCM arg2) |
| 3409 | { |
| 3410 | const SCM env = SCM_EXTEND_ENV (SCM_CLOSURE_FORMALS (proc), |
| 3411 | scm_list_2 (arg1, arg2), |
| 3412 | SCM_ENV (proc)); |
| 3413 | const SCM result = scm_eval_body (SCM_CLOSURE_BODY (proc), env); |
| 3414 | return result; |
| 3415 | } |
| 3416 | |
| 3417 | scm_t_trampoline_2 |
| 3418 | scm_trampoline_2 (SCM proc) |
| 3419 | { |
| 3420 | scm_t_trampoline_2 trampoline; |
| 3421 | |
| 3422 | if (SCM_IMP (proc)) |
| 3423 | return NULL; |
| 3424 | |
| 3425 | switch (SCM_TYP7 (proc)) |
| 3426 | { |
| 3427 | case scm_tc7_subr_2: |
| 3428 | case scm_tc7_subr_2o: |
| 3429 | case scm_tc7_rpsubr: |
| 3430 | case scm_tc7_asubr: |
| 3431 | trampoline = call_subr2_2; |
| 3432 | break; |
| 3433 | case scm_tc7_lsubr_2: |
| 3434 | trampoline = call_lsubr2_2; |
| 3435 | break; |
| 3436 | case scm_tc7_lsubr: |
| 3437 | trampoline = call_lsubr_2; |
| 3438 | break; |
| 3439 | case scm_tcs_closures: |
| 3440 | { |
| 3441 | SCM formals = SCM_CLOSURE_FORMALS (proc); |
| 3442 | if (!scm_is_null (formals) |
| 3443 | && (!scm_is_pair (formals) |
| 3444 | || (!scm_is_null (SCM_CDR (formals)) |
| 3445 | && (!scm_is_pair (SCM_CDR (formals)) |
| 3446 | || !scm_is_pair (SCM_CDDR (formals)))))) |
| 3447 | trampoline = call_closure_2; |
| 3448 | else |
| 3449 | return NULL; |
| 3450 | break; |
| 3451 | } |
| 3452 | case scm_tcs_struct: |
| 3453 | if (SCM_OBJ_CLASS_FLAGS (proc) & SCM_CLASSF_PURE_GENERIC) |
| 3454 | trampoline = scm_call_generic_2; |
| 3455 | else if (SCM_I_OPERATORP (proc)) |
| 3456 | trampoline = scm_call_2; |
| 3457 | else |
| 3458 | return NULL; |
| 3459 | break; |
| 3460 | case scm_tc7_smob: |
| 3461 | if (SCM_SMOB_APPLICABLE_P (proc)) |
| 3462 | trampoline = SCM_SMOB_DESCRIPTOR (proc).apply_2; |
| 3463 | else |
| 3464 | return NULL; |
| 3465 | break; |
| 3466 | case scm_tc7_gsubr: |
| 3467 | case scm_tc7_pws: |
| 3468 | trampoline = scm_call_2; |
| 3469 | break; |
| 3470 | default: |
| 3471 | return NULL; /* not applicable on two args */ |
| 3472 | } |
| 3473 | /* We only reach this point if a valid trampoline was determined. */ |
| 3474 | |
| 3475 | /* If debugging is enabled, we want to see all calls to proc on the stack. |
| 3476 | * Thus, we replace the trampoline shortcut with scm_call_2. */ |
| 3477 | if (scm_debug_mode_p) |
| 3478 | return scm_call_2; |
| 3479 | else |
| 3480 | return trampoline; |
| 3481 | } |
| 3482 | |
| 3483 | /* Typechecking for multi-argument MAP and FOR-EACH. |
| 3484 | |
| 3485 | Verify that each element of the vector ARGV, except for the first, |
| 3486 | is a proper list whose length is LEN. Attribute errors to WHO, |
| 3487 | and claim that the i'th element of ARGV is WHO's i+2'th argument. */ |
| 3488 | static inline void |
| 3489 | check_map_args (SCM argv, |
| 3490 | long len, |
| 3491 | SCM gf, |
| 3492 | SCM proc, |
| 3493 | SCM args, |
| 3494 | const char *who) |
| 3495 | { |
| 3496 | long i; |
| 3497 | |
| 3498 | for (i = SCM_SIMPLE_VECTOR_LENGTH (argv) - 1; i >= 1; i--) |
| 3499 | { |
| 3500 | SCM elt = SCM_SIMPLE_VECTOR_REF (argv, i); |
| 3501 | long elt_len = scm_ilength (elt); |
| 3502 | |
| 3503 | if (elt_len < 0) |
| 3504 | { |
| 3505 | if (gf) |
| 3506 | scm_apply_generic (gf, scm_cons (proc, args)); |
| 3507 | else |
| 3508 | scm_wrong_type_arg (who, i + 2, elt); |
| 3509 | } |
| 3510 | |
| 3511 | if (elt_len != len) |
| 3512 | scm_out_of_range_pos (who, elt, scm_from_long (i + 2)); |
| 3513 | } |
| 3514 | } |
| 3515 | |
| 3516 | |
| 3517 | SCM_GPROC (s_map, "map", 2, 0, 1, scm_map, g_map); |
| 3518 | |
| 3519 | /* Note: Currently, scm_map applies PROC to the argument list(s) |
| 3520 | sequentially, starting with the first element(s). This is used in |
| 3521 | evalext.c where the Scheme procedure `map-in-order', which guarantees |
| 3522 | sequential behaviour, is implemented using scm_map. If the |
| 3523 | behaviour changes, we need to update `map-in-order'. |
| 3524 | */ |
| 3525 | |
| 3526 | SCM |
| 3527 | scm_map (SCM proc, SCM arg1, SCM args) |
| 3528 | #define FUNC_NAME s_map |
| 3529 | { |
| 3530 | long i, len; |
| 3531 | SCM res = SCM_EOL; |
| 3532 | SCM *pres = &res; |
| 3533 | |
| 3534 | len = scm_ilength (arg1); |
| 3535 | SCM_GASSERTn (len >= 0, |
| 3536 | g_map, scm_cons2 (proc, arg1, args), SCM_ARG2, s_map); |
| 3537 | SCM_VALIDATE_REST_ARGUMENT (args); |
| 3538 | if (scm_is_null (args)) |
| 3539 | { |
| 3540 | scm_t_trampoline_1 call = scm_trampoline_1 (proc); |
| 3541 | SCM_GASSERT2 (call, g_map, proc, arg1, SCM_ARG1, s_map); |
| 3542 | while (SCM_NIMP (arg1)) |
| 3543 | { |
| 3544 | *pres = scm_list_1 (call (proc, SCM_CAR (arg1))); |
| 3545 | pres = SCM_CDRLOC (*pres); |
| 3546 | arg1 = SCM_CDR (arg1); |
| 3547 | } |
| 3548 | return res; |
| 3549 | } |
| 3550 | if (scm_is_null (SCM_CDR (args))) |
| 3551 | { |
| 3552 | SCM arg2 = SCM_CAR (args); |
| 3553 | int len2 = scm_ilength (arg2); |
| 3554 | scm_t_trampoline_2 call = scm_trampoline_2 (proc); |
| 3555 | SCM_GASSERTn (call, |
| 3556 | g_map, scm_cons2 (proc, arg1, args), SCM_ARG1, s_map); |
| 3557 | SCM_GASSERTn (len2 >= 0, |
| 3558 | g_map, scm_cons2 (proc, arg1, args), SCM_ARG3, s_map); |
| 3559 | if (len2 != len) |
| 3560 | SCM_OUT_OF_RANGE (3, arg2); |
| 3561 | while (SCM_NIMP (arg1)) |
| 3562 | { |
| 3563 | *pres = scm_list_1 (call (proc, SCM_CAR (arg1), SCM_CAR (arg2))); |
| 3564 | pres = SCM_CDRLOC (*pres); |
| 3565 | arg1 = SCM_CDR (arg1); |
| 3566 | arg2 = SCM_CDR (arg2); |
| 3567 | } |
| 3568 | return res; |
| 3569 | } |
| 3570 | arg1 = scm_cons (arg1, args); |
| 3571 | args = scm_vector (arg1); |
| 3572 | check_map_args (args, len, g_map, proc, arg1, s_map); |
| 3573 | while (1) |
| 3574 | { |
| 3575 | arg1 = SCM_EOL; |
| 3576 | for (i = SCM_SIMPLE_VECTOR_LENGTH (args) - 1; i >= 0; i--) |
| 3577 | { |
| 3578 | SCM elt = SCM_SIMPLE_VECTOR_REF (args, i); |
| 3579 | if (SCM_IMP (elt)) |
| 3580 | return res; |
| 3581 | arg1 = scm_cons (SCM_CAR (elt), arg1); |
| 3582 | SCM_SIMPLE_VECTOR_SET (args, i, SCM_CDR (elt)); |
| 3583 | } |
| 3584 | *pres = scm_list_1 (scm_apply (proc, arg1, SCM_EOL)); |
| 3585 | pres = SCM_CDRLOC (*pres); |
| 3586 | } |
| 3587 | } |
| 3588 | #undef FUNC_NAME |
| 3589 | |
| 3590 | |
| 3591 | SCM_GPROC (s_for_each, "for-each", 2, 0, 1, scm_for_each, g_for_each); |
| 3592 | |
| 3593 | SCM |
| 3594 | scm_for_each (SCM proc, SCM arg1, SCM args) |
| 3595 | #define FUNC_NAME s_for_each |
| 3596 | { |
| 3597 | long i, len; |
| 3598 | len = scm_ilength (arg1); |
| 3599 | SCM_GASSERTn (len >= 0, g_for_each, scm_cons2 (proc, arg1, args), |
| 3600 | SCM_ARG2, s_for_each); |
| 3601 | SCM_VALIDATE_REST_ARGUMENT (args); |
| 3602 | if (scm_is_null (args)) |
| 3603 | { |
| 3604 | scm_t_trampoline_1 call = scm_trampoline_1 (proc); |
| 3605 | SCM_GASSERT2 (call, g_for_each, proc, arg1, SCM_ARG1, s_for_each); |
| 3606 | while (SCM_NIMP (arg1)) |
| 3607 | { |
| 3608 | call (proc, SCM_CAR (arg1)); |
| 3609 | arg1 = SCM_CDR (arg1); |
| 3610 | } |
| 3611 | return SCM_UNSPECIFIED; |
| 3612 | } |
| 3613 | if (scm_is_null (SCM_CDR (args))) |
| 3614 | { |
| 3615 | SCM arg2 = SCM_CAR (args); |
| 3616 | int len2 = scm_ilength (arg2); |
| 3617 | scm_t_trampoline_2 call = scm_trampoline_2 (proc); |
| 3618 | SCM_GASSERTn (call, g_for_each, |
| 3619 | scm_cons2 (proc, arg1, args), SCM_ARG1, s_for_each); |
| 3620 | SCM_GASSERTn (len2 >= 0, g_for_each, |
| 3621 | scm_cons2 (proc, arg1, args), SCM_ARG3, s_for_each); |
| 3622 | if (len2 != len) |
| 3623 | SCM_OUT_OF_RANGE (3, arg2); |
| 3624 | while (SCM_NIMP (arg1)) |
| 3625 | { |
| 3626 | call (proc, SCM_CAR (arg1), SCM_CAR (arg2)); |
| 3627 | arg1 = SCM_CDR (arg1); |
| 3628 | arg2 = SCM_CDR (arg2); |
| 3629 | } |
| 3630 | return SCM_UNSPECIFIED; |
| 3631 | } |
| 3632 | arg1 = scm_cons (arg1, args); |
| 3633 | args = scm_vector (arg1); |
| 3634 | check_map_args (args, len, g_for_each, proc, arg1, s_for_each); |
| 3635 | while (1) |
| 3636 | { |
| 3637 | arg1 = SCM_EOL; |
| 3638 | for (i = SCM_SIMPLE_VECTOR_LENGTH (args) - 1; i >= 0; i--) |
| 3639 | { |
| 3640 | SCM elt = SCM_SIMPLE_VECTOR_REF (args, i); |
| 3641 | if (SCM_IMP (elt)) |
| 3642 | return SCM_UNSPECIFIED; |
| 3643 | arg1 = scm_cons (SCM_CAR (elt), arg1); |
| 3644 | SCM_SIMPLE_VECTOR_SET (args, i, SCM_CDR (elt)); |
| 3645 | } |
| 3646 | scm_apply (proc, arg1, SCM_EOL); |
| 3647 | } |
| 3648 | } |
| 3649 | #undef FUNC_NAME |
| 3650 | |
| 3651 | |
| 3652 | SCM |
| 3653 | scm_closure (SCM code, SCM env) |
| 3654 | { |
| 3655 | SCM z; |
| 3656 | SCM closcar = scm_cons (code, SCM_EOL); |
| 3657 | z = scm_immutable_cell (SCM_UNPACK (closcar) + scm_tc3_closure, |
| 3658 | (scm_t_bits) env); |
| 3659 | scm_remember_upto_here (closcar); |
| 3660 | return z; |
| 3661 | } |
| 3662 | |
| 3663 | |
| 3664 | scm_t_bits scm_tc16_promise; |
| 3665 | |
| 3666 | SCM |
| 3667 | scm_makprom (SCM code) |
| 3668 | { |
| 3669 | SCM_RETURN_NEWSMOB2 (scm_tc16_promise, |
| 3670 | SCM_UNPACK (code), |
| 3671 | scm_make_recursive_mutex ()); |
| 3672 | } |
| 3673 | |
| 3674 | |
| 3675 | static int |
| 3676 | promise_print (SCM exp, SCM port, scm_print_state *pstate) |
| 3677 | { |
| 3678 | int writingp = SCM_WRITINGP (pstate); |
| 3679 | scm_puts ("#<promise ", port); |
| 3680 | SCM_SET_WRITINGP (pstate, 1); |
| 3681 | scm_iprin1 (SCM_PROMISE_DATA (exp), port, pstate); |
| 3682 | SCM_SET_WRITINGP (pstate, writingp); |
| 3683 | scm_putc ('>', port); |
| 3684 | return !0; |
| 3685 | } |
| 3686 | |
| 3687 | SCM_DEFINE (scm_force, "force", 1, 0, 0, |
| 3688 | (SCM promise), |
| 3689 | "If the promise @var{x} has not been computed yet, compute and\n" |
| 3690 | "return @var{x}, otherwise just return the previously computed\n" |
| 3691 | "value.") |
| 3692 | #define FUNC_NAME s_scm_force |
| 3693 | { |
| 3694 | SCM_VALIDATE_SMOB (1, promise, promise); |
| 3695 | scm_lock_mutex (SCM_PROMISE_MUTEX (promise)); |
| 3696 | if (!SCM_PROMISE_COMPUTED_P (promise)) |
| 3697 | { |
| 3698 | SCM ans = scm_call_0 (SCM_PROMISE_DATA (promise)); |
| 3699 | if (!SCM_PROMISE_COMPUTED_P (promise)) |
| 3700 | { |
| 3701 | SCM_SET_PROMISE_DATA (promise, ans); |
| 3702 | SCM_SET_PROMISE_COMPUTED (promise); |
| 3703 | } |
| 3704 | } |
| 3705 | scm_unlock_mutex (SCM_PROMISE_MUTEX (promise)); |
| 3706 | return SCM_PROMISE_DATA (promise); |
| 3707 | } |
| 3708 | #undef FUNC_NAME |
| 3709 | |
| 3710 | |
| 3711 | SCM_DEFINE (scm_promise_p, "promise?", 1, 0, 0, |
| 3712 | (SCM obj), |
| 3713 | "Return true if @var{obj} is a promise, i.e. a delayed computation\n" |
| 3714 | "(@pxref{Delayed evaluation,,,r5rs.info,The Revised^5 Report on Scheme}).") |
| 3715 | #define FUNC_NAME s_scm_promise_p |
| 3716 | { |
| 3717 | return scm_from_bool (SCM_TYP16_PREDICATE (scm_tc16_promise, obj)); |
| 3718 | } |
| 3719 | #undef FUNC_NAME |
| 3720 | |
| 3721 | |
| 3722 | SCM_DEFINE (scm_cons_source, "cons-source", 3, 0, 0, |
| 3723 | (SCM xorig, SCM x, SCM y), |
| 3724 | "Create and return a new pair whose car and cdr are @var{x} and @var{y}.\n" |
| 3725 | "Any source properties associated with @var{xorig} are also associated\n" |
| 3726 | "with the new pair.") |
| 3727 | #define FUNC_NAME s_scm_cons_source |
| 3728 | { |
| 3729 | SCM p, z; |
| 3730 | z = scm_cons (x, y); |
| 3731 | /* Copy source properties possibly associated with xorig. */ |
| 3732 | p = scm_whash_lookup (scm_source_whash, xorig); |
| 3733 | if (scm_is_true (p)) |
| 3734 | scm_whash_insert (scm_source_whash, z, p); |
| 3735 | return z; |
| 3736 | } |
| 3737 | #undef FUNC_NAME |
| 3738 | |
| 3739 | |
| 3740 | /* The function scm_copy_tree is used to copy an expression tree to allow the |
| 3741 | * memoizer to modify the expression during memoization. scm_copy_tree |
| 3742 | * creates deep copies of pairs and vectors, but not of any other data types, |
| 3743 | * since only pairs and vectors will be parsed by the memoizer. |
| 3744 | * |
| 3745 | * To avoid infinite recursion due to cyclic structures, the hare-and-tortoise |
| 3746 | * pattern is used to detect cycles. In fact, the pattern is used in two |
| 3747 | * dimensions, vertical (indicated in the code by the variable names 'hare' |
| 3748 | * and 'tortoise') and horizontal ('rabbit' and 'turtle'). In both |
| 3749 | * dimensions, the hare/rabbit will take two steps when the tortoise/turtle |
| 3750 | * takes one. |
| 3751 | * |
| 3752 | * The vertical dimension corresponds to recursive calls to function |
| 3753 | * copy_tree: This happens when descending into vector elements, into cars of |
| 3754 | * lists and into the cdr of an improper list. In this dimension, the |
| 3755 | * tortoise follows the hare by using the processor stack: Every stack frame |
| 3756 | * will hold an instance of struct t_trace. These instances are connected in |
| 3757 | * a way that represents the trace of the hare, which thus can be followed by |
| 3758 | * the tortoise. The tortoise will always point to struct t_trace instances |
| 3759 | * relating to SCM objects that have already been copied. Thus, a cycle is |
| 3760 | * detected if the tortoise and the hare point to the same object, |
| 3761 | * |
| 3762 | * The horizontal dimension is within one execution of copy_tree, when the |
| 3763 | * function cdr's along the pairs of a list. This is the standard |
| 3764 | * hare-and-tortoise implementation, found several times in guile. */ |
| 3765 | |
| 3766 | struct t_trace { |
| 3767 | struct t_trace *trace; /* These pointers form a trace along the stack. */ |
| 3768 | SCM obj; /* The object handled at the respective stack frame.*/ |
| 3769 | }; |
| 3770 | |
| 3771 | static SCM |
| 3772 | copy_tree ( |
| 3773 | struct t_trace *const hare, |
| 3774 | struct t_trace *tortoise, |
| 3775 | unsigned int tortoise_delay ) |
| 3776 | { |
| 3777 | if (!scm_is_pair (hare->obj) && !scm_is_simple_vector (hare->obj)) |
| 3778 | { |
| 3779 | return hare->obj; |
| 3780 | } |
| 3781 | else |
| 3782 | { |
| 3783 | /* Prepare the trace along the stack. */ |
| 3784 | struct t_trace new_hare; |
| 3785 | hare->trace = &new_hare; |
| 3786 | |
| 3787 | /* The tortoise will make its step after the delay has elapsed. Note |
| 3788 | * that in contrast to the typical hare-and-tortoise pattern, the step |
| 3789 | * of the tortoise happens before the hare takes its steps. This is, in |
| 3790 | * principle, no problem, except for the start of the algorithm: Then, |
| 3791 | * it has to be made sure that the hare actually gets its advantage of |
| 3792 | * two steps. */ |
| 3793 | if (tortoise_delay == 0) |
| 3794 | { |
| 3795 | tortoise_delay = 1; |
| 3796 | tortoise = tortoise->trace; |
| 3797 | ASSERT_SYNTAX (!scm_is_eq (hare->obj, tortoise->obj), |
| 3798 | s_bad_expression, hare->obj); |
| 3799 | } |
| 3800 | else |
| 3801 | { |
| 3802 | --tortoise_delay; |
| 3803 | } |
| 3804 | |
| 3805 | if (scm_is_simple_vector (hare->obj)) |
| 3806 | { |
| 3807 | size_t length = SCM_SIMPLE_VECTOR_LENGTH (hare->obj); |
| 3808 | SCM new_vector = scm_c_make_vector (length, SCM_UNSPECIFIED); |
| 3809 | |
| 3810 | /* Each vector element is copied by recursing into copy_tree, having |
| 3811 | * the tortoise follow the hare into the depths of the stack. */ |
| 3812 | unsigned long int i; |
| 3813 | for (i = 0; i < length; ++i) |
| 3814 | { |
| 3815 | SCM new_element; |
| 3816 | new_hare.obj = SCM_SIMPLE_VECTOR_REF (hare->obj, i); |
| 3817 | new_element = copy_tree (&new_hare, tortoise, tortoise_delay); |
| 3818 | SCM_SIMPLE_VECTOR_SET (new_vector, i, new_element); |
| 3819 | } |
| 3820 | |
| 3821 | return new_vector; |
| 3822 | } |
| 3823 | else /* scm_is_pair (hare->obj) */ |
| 3824 | { |
| 3825 | SCM result; |
| 3826 | SCM tail; |
| 3827 | |
| 3828 | SCM rabbit = hare->obj; |
| 3829 | SCM turtle = hare->obj; |
| 3830 | |
| 3831 | SCM copy; |
| 3832 | |
| 3833 | /* The first pair of the list is treated specially, in order to |
| 3834 | * preserve a potential source code position. */ |
| 3835 | result = tail = scm_cons_source (rabbit, SCM_EOL, SCM_EOL); |
| 3836 | new_hare.obj = SCM_CAR (rabbit); |
| 3837 | copy = copy_tree (&new_hare, tortoise, tortoise_delay); |
| 3838 | SCM_SETCAR (tail, copy); |
| 3839 | |
| 3840 | /* The remaining pairs of the list are copied by, horizontally, |
| 3841 | * having the turtle follow the rabbit, and, vertically, having the |
| 3842 | * tortoise follow the hare into the depths of the stack. */ |
| 3843 | rabbit = SCM_CDR (rabbit); |
| 3844 | while (scm_is_pair (rabbit)) |
| 3845 | { |
| 3846 | new_hare.obj = SCM_CAR (rabbit); |
| 3847 | copy = copy_tree (&new_hare, tortoise, tortoise_delay); |
| 3848 | SCM_SETCDR (tail, scm_cons (copy, SCM_UNDEFINED)); |
| 3849 | tail = SCM_CDR (tail); |
| 3850 | |
| 3851 | rabbit = SCM_CDR (rabbit); |
| 3852 | if (scm_is_pair (rabbit)) |
| 3853 | { |
| 3854 | new_hare.obj = SCM_CAR (rabbit); |
| 3855 | copy = copy_tree (&new_hare, tortoise, tortoise_delay); |
| 3856 | SCM_SETCDR (tail, scm_cons (copy, SCM_UNDEFINED)); |
| 3857 | tail = SCM_CDR (tail); |
| 3858 | rabbit = SCM_CDR (rabbit); |
| 3859 | |
| 3860 | turtle = SCM_CDR (turtle); |
| 3861 | ASSERT_SYNTAX (!scm_is_eq (rabbit, turtle), |
| 3862 | s_bad_expression, rabbit); |
| 3863 | } |
| 3864 | } |
| 3865 | |
| 3866 | /* We have to recurse into copy_tree again for the last cdr, in |
| 3867 | * order to handle the situation that it holds a vector. */ |
| 3868 | new_hare.obj = rabbit; |
| 3869 | copy = copy_tree (&new_hare, tortoise, tortoise_delay); |
| 3870 | SCM_SETCDR (tail, copy); |
| 3871 | |
| 3872 | return result; |
| 3873 | } |
| 3874 | } |
| 3875 | } |
| 3876 | |
| 3877 | SCM_DEFINE (scm_copy_tree, "copy-tree", 1, 0, 0, |
| 3878 | (SCM obj), |
| 3879 | "Recursively copy the data tree that is bound to @var{obj}, and return a\n" |
| 3880 | "the new data structure. @code{copy-tree} recurses down the\n" |
| 3881 | "contents of both pairs and vectors (since both cons cells and vector\n" |
| 3882 | "cells may point to arbitrary objects), and stops recursing when it hits\n" |
| 3883 | "any other object.") |
| 3884 | #define FUNC_NAME s_scm_copy_tree |
| 3885 | { |
| 3886 | /* Prepare the trace along the stack. */ |
| 3887 | struct t_trace trace; |
| 3888 | trace.obj = obj; |
| 3889 | |
| 3890 | /* In function copy_tree, if the tortoise makes its step, it will do this |
| 3891 | * before the hare has the chance to move. Thus, we have to make sure that |
| 3892 | * the very first step of the tortoise will not happen after the hare has |
| 3893 | * really made two steps. This is achieved by passing '2' as the initial |
| 3894 | * delay for the tortoise. NOTE: Since cycles are unlikely, giving the hare |
| 3895 | * a bigger advantage may improve performance slightly. */ |
| 3896 | return copy_tree (&trace, &trace, 2); |
| 3897 | } |
| 3898 | #undef FUNC_NAME |
| 3899 | |
| 3900 | |
| 3901 | /* We have three levels of EVAL here: |
| 3902 | |
| 3903 | - scm_i_eval (exp, env) |
| 3904 | |
| 3905 | evaluates EXP in environment ENV. ENV is a lexical environment |
| 3906 | structure as used by the actual tree code evaluator. When ENV is |
| 3907 | a top-level environment, then changes to the current module are |
| 3908 | tracked by updating ENV so that it continues to be in sync with |
| 3909 | the current module. |
| 3910 | |
| 3911 | - scm_primitive_eval (exp) |
| 3912 | |
| 3913 | evaluates EXP in the top-level environment as determined by the |
| 3914 | current module. This is done by constructing a suitable |
| 3915 | environment and calling scm_i_eval. Thus, changes to the |
| 3916 | top-level module are tracked normally. |
| 3917 | |
| 3918 | - scm_eval (exp, mod_or_state) |
| 3919 | |
| 3920 | evaluates EXP while MOD_OR_STATE is the current module or current |
| 3921 | dynamic state (as appropriate). This is done by setting the |
| 3922 | current module (or dynamic state) to MOD_OR_STATE, invoking |
| 3923 | scm_primitive_eval on EXP, and then restoring the current module |
| 3924 | (or dynamic state) to the value it had previously. That is, |
| 3925 | while EXP is evaluated, changes to the current module (or dynamic |
| 3926 | state) are tracked, but these changes do not persist when |
| 3927 | scm_eval returns. |
| 3928 | |
| 3929 | For each level of evals, there are two variants, distinguished by a |
| 3930 | _x suffix: the ordinary variant does not modify EXP while the _x |
| 3931 | variant can destructively modify EXP into something completely |
| 3932 | unintelligible. A Scheme data structure passed as EXP to one of the |
| 3933 | _x variants should not ever be used again for anything. So when in |
| 3934 | doubt, use the ordinary variant. |
| 3935 | |
| 3936 | */ |
| 3937 | |
| 3938 | SCM |
| 3939 | scm_i_eval_x (SCM exp, SCM env) |
| 3940 | { |
| 3941 | if (scm_is_symbol (exp)) |
| 3942 | return *scm_lookupcar (scm_cons (exp, SCM_UNDEFINED), env, 1); |
| 3943 | else |
| 3944 | return SCM_I_XEVAL (exp, env, scm_debug_mode_p); |
| 3945 | } |
| 3946 | |
| 3947 | SCM |
| 3948 | scm_i_eval (SCM exp, SCM env) |
| 3949 | { |
| 3950 | exp = scm_copy_tree (exp); |
| 3951 | if (scm_is_symbol (exp)) |
| 3952 | return *scm_lookupcar (scm_cons (exp, SCM_UNDEFINED), env, 1); |
| 3953 | else |
| 3954 | return SCM_I_XEVAL (exp, env, scm_debug_mode_p); |
| 3955 | } |
| 3956 | |
| 3957 | SCM |
| 3958 | scm_primitive_eval_x (SCM exp) |
| 3959 | { |
| 3960 | SCM env; |
| 3961 | SCM transformer = scm_current_module_transformer (); |
| 3962 | if (SCM_NIMP (transformer)) |
| 3963 | exp = scm_call_1 (transformer, exp); |
| 3964 | env = scm_top_level_env (scm_current_module_lookup_closure ()); |
| 3965 | return scm_i_eval_x (exp, env); |
| 3966 | } |
| 3967 | |
| 3968 | SCM_DEFINE (scm_primitive_eval, "primitive-eval", 1, 0, 0, |
| 3969 | (SCM exp), |
| 3970 | "Evaluate @var{exp} in the top-level environment specified by\n" |
| 3971 | "the current module.") |
| 3972 | #define FUNC_NAME s_scm_primitive_eval |
| 3973 | { |
| 3974 | SCM env; |
| 3975 | SCM transformer = scm_current_module_transformer (); |
| 3976 | if (scm_is_true (transformer)) |
| 3977 | exp = scm_call_1 (transformer, exp); |
| 3978 | env = scm_top_level_env (scm_current_module_lookup_closure ()); |
| 3979 | return scm_i_eval (exp, env); |
| 3980 | } |
| 3981 | #undef FUNC_NAME |
| 3982 | |
| 3983 | |
| 3984 | /* Eval does not take the second arg optionally. This is intentional |
| 3985 | * in order to be R5RS compatible, and to prepare for the new module |
| 3986 | * system, where we would like to make the choice of evaluation |
| 3987 | * environment explicit. */ |
| 3988 | |
| 3989 | SCM |
| 3990 | scm_eval_x (SCM exp, SCM module_or_state) |
| 3991 | { |
| 3992 | SCM res; |
| 3993 | |
| 3994 | scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE); |
| 3995 | if (scm_is_dynamic_state (module_or_state)) |
| 3996 | scm_dynwind_current_dynamic_state (module_or_state); |
| 3997 | else |
| 3998 | scm_dynwind_current_module (module_or_state); |
| 3999 | |
| 4000 | res = scm_primitive_eval_x (exp); |
| 4001 | |
| 4002 | scm_dynwind_end (); |
| 4003 | return res; |
| 4004 | } |
| 4005 | |
| 4006 | SCM_DEFINE (scm_eval, "eval", 2, 0, 0, |
| 4007 | (SCM exp, SCM module_or_state), |
| 4008 | "Evaluate @var{exp}, a list representing a Scheme expression,\n" |
| 4009 | "in the top-level environment specified by\n" |
| 4010 | "@var{module_or_state}.\n" |
| 4011 | "While @var{exp} is evaluated (using @code{primitive-eval}),\n" |
| 4012 | "@var{module_or_state} is made the current module when\n" |
| 4013 | "it is a module, or the current dynamic state when it is\n" |
| 4014 | "a dynamic state." |
| 4015 | "Example: (eval '(+ 1 2) (interaction-environment))") |
| 4016 | #define FUNC_NAME s_scm_eval |
| 4017 | { |
| 4018 | SCM res; |
| 4019 | |
| 4020 | scm_dynwind_begin (SCM_F_DYNWIND_REWINDABLE); |
| 4021 | if (scm_is_dynamic_state (module_or_state)) |
| 4022 | scm_dynwind_current_dynamic_state (module_or_state); |
| 4023 | else |
| 4024 | { |
| 4025 | SCM_VALIDATE_MODULE (2, module_or_state); |
| 4026 | scm_dynwind_current_module (module_or_state); |
| 4027 | } |
| 4028 | |
| 4029 | res = scm_primitive_eval (exp); |
| 4030 | |
| 4031 | scm_dynwind_end (); |
| 4032 | return res; |
| 4033 | } |
| 4034 | #undef FUNC_NAME |
| 4035 | |
| 4036 | |
| 4037 | /* At this point, deval and scm_dapply are generated. |
| 4038 | */ |
| 4039 | |
| 4040 | #define DEVAL |
| 4041 | #include "eval.i.c" |
| 4042 | #undef DEVAL |
| 4043 | #include "eval.i.c" |
| 4044 | |
| 4045 | |
| 4046 | void |
| 4047 | scm_init_eval () |
| 4048 | { |
| 4049 | scm_i_pthread_mutex_init (&source_mutex, |
| 4050 | scm_i_pthread_mutexattr_recursive); |
| 4051 | |
| 4052 | scm_init_opts (scm_evaluator_traps, |
| 4053 | scm_evaluator_trap_table); |
| 4054 | scm_init_opts (scm_eval_options_interface, |
| 4055 | scm_eval_opts); |
| 4056 | |
| 4057 | scm_tc16_promise = scm_make_smob_type ("promise", 0); |
| 4058 | scm_set_smob_print (scm_tc16_promise, promise_print); |
| 4059 | |
| 4060 | undefineds = scm_list_1 (SCM_UNDEFINED); |
| 4061 | SCM_SETCDR (undefineds, undefineds); |
| 4062 | scm_permanent_object (undefineds); |
| 4063 | |
| 4064 | scm_listofnull = scm_list_1 (SCM_EOL); |
| 4065 | |
| 4066 | f_apply = scm_c_define_subr ("apply", scm_tc7_lsubr_2, scm_apply); |
| 4067 | scm_permanent_object (f_apply); |
| 4068 | |
| 4069 | #include "libguile/eval.x" |
| 4070 | |
| 4071 | scm_add_feature ("delay"); |
| 4072 | } |
| 4073 | |
| 4074 | /* |
| 4075 | Local Variables: |
| 4076 | c-file-style: "gnu" |
| 4077 | End: |
| 4078 | */ |
| 4079 | |