libguile/symbols.c

   1 /* Copyright (C) 1995, 1996, 1997, 1998, 2000, 2001, 2003, 2004,
   2  *   2006, 2009, 2011 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 License
   6  * as published by the Free Software Foundation; either version 3 of
   7  * the License, or (at your option) any later version.
   8  *
   9  * This library is distributed in the hope that it will be useful, but
  10  * 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
  17  * 02110-1301 USA
  18  */
  19
  20
  21 \f
  22 #ifdef HAVE_CONFIG_H
  23 #  include <config.h>
  24 #endif
  25
  26 #include "libguile/_scm.h"
  27 #include "libguile/chars.h"
  28 #include "libguile/eval.h"
  29 #include "libguile/hash.h"
  30 #include "libguile/smob.h"
  31 #include "libguile/variable.h"
  32 #include "libguile/alist.h"
  33 #include "libguile/fluids.h"
  34 #include "libguile/strings.h"
  35 #include "libguile/vectors.h"
  36 #include "libguile/hashtab.h"
  37 #include "libguile/weaks.h"
  38 #include "libguile/modules.h"
  39 #include "libguile/read.h"
  40 #include "libguile/srfi-13.h"
  41
  42 #include "libguile/validate.h"
  43 #include "libguile/symbols.h"
  44
  45 #include "libguile/private-options.h"
  46
  47
  48 #ifdef HAVE_STRING_H
  49 #include <string.h>
  50 #endif
  51
  52 \f
  53
  54 static SCM symbols;
  55 static scm_i_pthread_mutex_t symbols_lock = SCM_I_PTHREAD_MUTEX_INITIALIZER;
  56
  57 #ifdef GUILE_DEBUG
  58 SCM_DEFINE (scm_sys_symbols, "%symbols", 0, 0, 0,
  59             (),
  60             "Return the system symbol obarray.")
  61 #define FUNC_NAME s_scm_sys_symbols
  62 {
  63   return symbols;
  64 }
  65 #undef FUNC_NAME
  66 #endif
  67
  68 \f
  69
  70 /* {Symbols}
  71  */
  72
  73 unsigned long
  74 scm_i_hash_symbol (SCM obj, unsigned long n, void *closure)
  75 {
  76   return scm_i_symbol_hash (obj) % n;
  77 }
  78
  79 struct string_lookup_data
  80 {
  81   SCM string;
  82   unsigned long string_hash;
  83 };
  84
  85 static int
  86 string_lookup_predicate_fn (SCM sym, void *closure)
  87 {
  88   struct string_lookup_data *data = closure;
  89
  90   if (scm_i_symbol_hash (sym) == data->string_hash
  91       && scm_i_symbol_length (sym) == scm_i_string_length (data->string))
  92     {
  93       size_t n = scm_i_symbol_length (sym);
  94       while (n--)
  95         if (scm_i_symbol_ref (sym, n) != scm_i_string_ref (data->string, n))
  96           return 0;
  97       return 1;
  98     }
  99   else
 100     return 0;
 101 }
 102
 103 static SCM
 104 lookup_interned_symbol (SCM name, unsigned long raw_hash)
 105 {
 106   struct string_lookup_data data;
 107   SCM handle;
 108
 109   data.string = name;
 110   data.string_hash = raw_hash;
 111
 112   scm_i_pthread_mutex_lock (&symbols_lock);
 113   handle = scm_hash_fn_get_handle_by_hash (symbols, raw_hash,
 114                                            string_lookup_predicate_fn,
 115                                            &data);
 116   scm_i_pthread_mutex_unlock (&symbols_lock);
 117
 118   if (scm_is_true (handle))
 119     return SCM_CAR (handle);
 120   else
 121     return SCM_BOOL_F;
 122 }
 123
 124 struct latin1_lookup_data
 125 {
 126   const char *str;
 127   size_t len;
 128   unsigned long string_hash;
 129 };
 130
 131 static int
 132 latin1_lookup_predicate_fn (SCM sym, void *closure)
 133 {
 134   struct latin1_lookup_data *data = closure;
 135
 136   return scm_i_symbol_hash (sym) == data->string_hash
 137     && scm_i_is_narrow_symbol (sym)
 138     && scm_i_symbol_length (sym) == data->len
 139     && strncmp (scm_i_symbol_chars (sym), data->str, data->len) == 0;
 140 }
 141
 142 static SCM
 143 lookup_interned_latin1_symbol (const char *str, size_t len,
 144                                unsigned long raw_hash)
 145 {
 146   struct latin1_lookup_data data;
 147   SCM handle;
 148
 149   data.str = str;
 150   data.len = len;
 151   data.string_hash = raw_hash;
 152
 153   scm_i_pthread_mutex_lock (&symbols_lock);
 154   handle = scm_hash_fn_get_handle_by_hash (symbols, raw_hash,
 155                                            latin1_lookup_predicate_fn,
 156                                            &data);
 157   scm_i_pthread_mutex_unlock (&symbols_lock);
 158
 159   if (scm_is_true (handle))
 160     return SCM_CAR (handle);
 161   else
 162     return SCM_BOOL_F;
 163 }
 164
 165 static unsigned long
 166 symbol_lookup_hash_fn (SCM obj, unsigned long max, void *closure)
 167 {
 168   return scm_i_symbol_hash (obj) % max;
 169 }
 170
 171 static SCM
 172 symbol_lookup_assoc_fn (SCM obj, SCM alist, void *closure)
 173 {
 174   for (; !scm_is_null (alist); alist = SCM_CDR (alist))
 175     {
 176       SCM sym = SCM_CAAR (alist);
 177
 178       if (scm_i_symbol_hash (sym) == scm_i_symbol_hash (obj)
 179           && scm_is_true (scm_string_equal_p (scm_symbol_to_string (sym),
 180                                               scm_symbol_to_string (obj))))
 181         return SCM_CAR (alist);
 182     }
 183
 184   return SCM_BOOL_F;
 185 }
 186
 187 /* Intern SYMBOL, an uninterned symbol.  Might return a different
 188    symbol, if another one was interned at the same time.  */
 189 static SCM
 190 intern_symbol (SCM symbol)
 191 {
 192   SCM handle;
 193
 194   scm_i_pthread_mutex_lock (&symbols_lock);
 195   handle = scm_hash_fn_create_handle_x (symbols, symbol, SCM_UNDEFINED,
 196                                         symbol_lookup_hash_fn,
 197                                         symbol_lookup_assoc_fn,
 198                                         NULL);
 199   scm_i_pthread_mutex_unlock (&symbols_lock);
 200
 201   return SCM_CAR (handle);
 202 }
 203
 204 static SCM
 205 scm_i_str2symbol (SCM str)
 206 {
 207   SCM symbol;
 208   size_t raw_hash = scm_i_string_hash (str);
 209
 210   symbol = lookup_interned_symbol (str, raw_hash);
 211   if (scm_is_true (symbol))
 212     return symbol;
 213   else
 214     {
 215       /* The symbol was not found, create it.  */
 216       symbol = scm_i_make_symbol (str, 0, raw_hash,
 217                                   scm_cons (SCM_BOOL_F, SCM_EOL));
 218       return intern_symbol (symbol);
 219     }
 220 }
 221
 222
 223 static SCM
 224 scm_i_str2uninterned_symbol (SCM str)
 225 {
 226   size_t raw_hash = scm_i_string_hash (str);
 227
 228   return scm_i_make_symbol (str, SCM_I_F_SYMBOL_UNINTERNED,
 229                             raw_hash, scm_cons (SCM_BOOL_F, SCM_EOL));
 230 }
 231
 232 SCM_DEFINE (scm_symbol_p, "symbol?", 1, 0, 0,
 233             (SCM obj),
 234             "Return @code{#t} if @var{obj} is a symbol, otherwise return\n"
 235             "@code{#f}.")
 236 #define FUNC_NAME s_scm_symbol_p
 237 {
 238   return scm_from_bool (scm_is_symbol (obj));
 239 }
 240 #undef FUNC_NAME
 241
 242 SCM_DEFINE (scm_symbol_interned_p, "symbol-interned?", 1, 0, 0,
 243             (SCM symbol),
 244             "Return @code{#t} if @var{symbol} is interned, otherwise return\n"
 245             "@code{#f}.")
 246 #define FUNC_NAME s_scm_symbol_interned_p
 247 {
 248   SCM_VALIDATE_SYMBOL (1, symbol);
 249   return scm_from_bool (scm_i_symbol_is_interned (symbol));
 250 }
 251 #undef FUNC_NAME
 252
 253 SCM_DEFINE (scm_make_symbol, "make-symbol", 1, 0, 0,
 254             (SCM name),
 255             "Return a new uninterned symbol with the name @var{name}.  "
 256             "The returned symbol is guaranteed to be unique and future "
 257             "calls to @code{string->symbol} will not return it.")
 258 #define FUNC_NAME s_scm_make_symbol
 259 {
 260   SCM_VALIDATE_STRING (1, name);
 261   return scm_i_str2uninterned_symbol (name);
 262 }
 263 #undef FUNC_NAME
 264
 265 SCM_DEFINE (scm_symbol_to_string, "symbol->string", 1, 0, 0,
 266            (SCM s),
 267             "Return the name of @var{symbol} as a string.  If the symbol was\n"
 268             "part of an object returned as the value of a literal expression\n"
 269             "(section @pxref{Literal expressions,,,r5rs, The Revised^5\n"
 270             "Report on Scheme}) or by a call to the @code{read} procedure,\n"
 271             "and its name contains alphabetic characters, then the string\n"
 272             "returned will contain characters in the implementation's\n"
 273             "preferred standard case---some implementations will prefer\n"
 274             "upper case, others lower case.  If the symbol was returned by\n"
 275             "@code{string->symbol}, the case of characters in the string\n"
 276             "returned will be the same as the case in the string that was\n"
 277             "passed to @code{string->symbol}.  It is an error to apply\n"
 278             "mutation procedures like @code{string-set!} to strings returned\n"
 279             "by this procedure.\n"
 280             "\n"
 281             "The following examples assume that the implementation's\n"
 282             "standard case is lower case:\n"
 283             "\n"
 284             "@lisp\n"
 285             "(symbol->string 'flying-fish)    @result{} \"flying-fish\"\n"
 286             "(symbol->string 'Martin)         @result{}  \"martin\"\n"
 287             "(symbol->string\n"
 288             "   (string->symbol \"Malvina\")) @result{} \"Malvina\"\n"
 289             "@end lisp")
 290 #define FUNC_NAME s_scm_symbol_to_string
 291 {
 292   SCM_VALIDATE_SYMBOL (1, s);
 293   return scm_i_symbol_substring (s, 0, scm_i_symbol_length (s));
 294 }
 295 #undef FUNC_NAME
 296
 297
 298 SCM_DEFINE (scm_string_to_symbol, "string->symbol", 1, 0, 0,
 299             (SCM string),
 300             "Return the symbol whose name is @var{string}. This procedure\n"
 301             "can create symbols with names containing special characters or\n"
 302             "letters in the non-standard case, but it is usually a bad idea\n"
 303             "to create such symbols because in some implementations of\n"
 304             "Scheme they cannot be read as themselves.  See\n"
 305             "@code{symbol->string}.\n"
 306             "\n"
 307             "The following examples assume that the implementation's\n"
 308             "standard case is lower case:\n"
 309             "\n"
 310             "@lisp\n"
 311             "(eq? 'mISSISSIppi 'mississippi) @result{} #t\n"
 312             "(string->symbol \"mISSISSIppi\") @result{} @r{the symbol with name \"mISSISSIppi\"}\n"
 313             "(eq? 'bitBlt (string->symbol \"bitBlt\")) @result{} #f\n"
 314             "(eq? 'JollyWog\n"
 315             "  (string->symbol (symbol->string 'JollyWog))) @result{} #t\n"
 316             "(string=? \"K. Harper, M.D.\"\n"
 317             "  (symbol->string\n"
 318             "    (string->symbol \"K. Harper, M.D.\"))) @result{}#t\n"
 319             "@end lisp")
 320 #define FUNC_NAME s_scm_string_to_symbol
 321 {
 322   SCM_VALIDATE_STRING (1, string);
 323   return scm_i_str2symbol (string);
 324 }
 325 #undef FUNC_NAME
 326
 327 SCM_DEFINE (scm_string_ci_to_symbol, "string-ci->symbol", 1, 0, 0,
 328             (SCM str),
 329             "Return the symbol whose name is @var{str}.  @var{str} is\n"
 330             "converted to lowercase before the conversion is done, if Guile\n"
 331             "is currently reading symbols case-insensitively.")
 332 #define FUNC_NAME s_scm_string_ci_to_symbol
 333 {
 334   return scm_string_to_symbol (SCM_CASE_INSENSITIVE_P
 335                                ? scm_string_downcase(str)
 336                                : str);
 337 }
 338 #undef FUNC_NAME
 339
 340 /* The default prefix for `gensym'd symbols.  */
 341 static SCM default_gensym_prefix;
 342
 343 #define MAX_PREFIX_LENGTH 30
 344
 345 SCM_DEFINE (scm_gensym, "gensym", 0, 1, 0,
 346             (SCM prefix),
 347             "Create a new symbol with a name constructed from a prefix and\n"
 348             "a counter value. The string @var{prefix} can be specified as\n"
 349             "an optional argument. Default prefix is @code{ g}.  The counter\n"
 350             "is increased by 1 at each call. There is no provision for\n"
 351             "resetting the counter.")
 352 #define FUNC_NAME s_scm_gensym
 353 {
 354   static int gensym_counter = 0;
 355
 356   SCM suffix, name;
 357   int n, n_digits;
 358   char buf[SCM_INTBUFLEN];
 359
 360   if (SCM_UNBNDP (prefix))
 361     prefix = default_gensym_prefix;
 362
 363   /* mutex in case another thread looks and incs at the exact same moment */
 364   scm_i_scm_pthread_mutex_lock (&scm_i_misc_mutex);
 365   n = gensym_counter++;
 366   scm_i_pthread_mutex_unlock (&scm_i_misc_mutex);
 367
 368   n_digits = scm_iint2str (n, 10, buf);
 369   suffix = scm_from_latin1_stringn (buf, n_digits);
 370   name = scm_string_append (scm_list_2 (prefix, suffix));
 371   return scm_string_to_symbol (name);
 372 }
 373 #undef FUNC_NAME
 374
 375 SCM_DEFINE (scm_symbol_hash, "symbol-hash", 1, 0, 0,
 376             (SCM symbol),
 377             "Return a hash value for @var{symbol}.")
 378 #define FUNC_NAME s_scm_symbol_hash
 379 {
 380   SCM_VALIDATE_SYMBOL (1, symbol);
 381   return scm_from_ulong (scm_i_symbol_hash (symbol));
 382 }
 383 #undef FUNC_NAME
 384
 385 SCM_DEFINE (scm_symbol_fref, "symbol-fref", 1, 0, 0,
 386            (SCM s),
 387             "Return the contents of the symbol @var{s}'s @dfn{function slot}.")
 388 #define FUNC_NAME s_scm_symbol_fref
 389 {
 390   SCM_VALIDATE_SYMBOL (1, s);
 391   return SCM_CAR (SCM_CELL_OBJECT_3 (s));
 392 }
 393 #undef FUNC_NAME
 394
 395
 396 SCM_DEFINE (scm_symbol_pref, "symbol-pref", 1, 0, 0,
 397            (SCM s),
 398             "Return the @dfn{property list} currently associated with the\n"
 399             "symbol @var{s}.")
 400 #define FUNC_NAME s_scm_symbol_pref
 401 {
 402   SCM_VALIDATE_SYMBOL (1, s);
 403   return SCM_CDR (SCM_CELL_OBJECT_3 (s));
 404 }
 405 #undef FUNC_NAME
 406
 407
 408 SCM_DEFINE (scm_symbol_fset_x, "symbol-fset!", 2, 0, 0,
 409            (SCM s, SCM val),
 410             "Change the binding of the symbol @var{s}'s function slot.")
 411 #define FUNC_NAME s_scm_symbol_fset_x
 412 {
 413   SCM_VALIDATE_SYMBOL (1, s);
 414   SCM_SETCAR (SCM_CELL_OBJECT_3 (s), val);
 415   return SCM_UNSPECIFIED;
 416 }
 417 #undef FUNC_NAME
 418
 419
 420 SCM_DEFINE (scm_symbol_pset_x, "symbol-pset!", 2, 0, 0,
 421            (SCM s, SCM val),
 422             "Change the binding of the symbol @var{s}'s property slot.")
 423 #define FUNC_NAME s_scm_symbol_pset_x
 424 {
 425   SCM_VALIDATE_SYMBOL (1, s);
 426   SCM_SETCDR (SCM_CELL_OBJECT_3 (s), val);
 427   return SCM_UNSPECIFIED;
 428 }
 429 #undef FUNC_NAME
 430
 431 SCM
 432 scm_from_locale_symbol (const char *sym)
 433 {
 434   return scm_from_locale_symboln (sym, -1);
 435 }
 436
 437 SCM
 438 scm_from_locale_symboln (const char *sym, size_t len)
 439 {
 440   SCM str = scm_from_locale_stringn (sym, len);
 441   return scm_i_str2symbol (str);
 442 }
 443
 444 SCM
 445 scm_take_locale_symboln (char *sym, size_t len)
 446 {
 447   SCM str;
 448
 449   str = scm_take_locale_stringn (sym, len);
 450   return scm_i_str2symbol (str);
 451 }
 452
 453 SCM
 454 scm_take_locale_symbol (char *sym)
 455 {
 456   return scm_take_locale_symboln (sym, (size_t)-1);
 457 }
 458
 459 SCM
 460 scm_from_latin1_symbol (const char *sym)
 461 {
 462   return scm_from_latin1_symboln (sym, -1);
 463 }
 464
 465 SCM
 466 scm_from_latin1_symboln (const char *sym, size_t len)
 467 {
 468   unsigned long hash;
 469   SCM ret;
 470
 471   if (len == (size_t) -1)
 472     len = strlen (sym);
 473   hash = scm_i_latin1_string_hash (sym, len);
 474
 475   ret = lookup_interned_latin1_symbol (sym, len, hash);
 476   if (scm_is_false (ret))
 477     {
 478       SCM str = scm_from_latin1_stringn (sym, len);
 479       ret = scm_i_str2symbol (str);
 480     }
 481
 482   return ret;
 483 }
 484
 485 SCM
 486 scm_from_utf8_symbol (const char *sym)
 487 {
 488   return scm_from_utf8_symboln (sym, -1);
 489 }
 490
 491 SCM
 492 scm_from_utf8_symboln (const char *sym, size_t len)
 493 {
 494   SCM str = scm_from_utf8_stringn (sym, len);
 495   return scm_i_str2symbol (str);
 496 }
 497
 498 void
 499 scm_symbols_prehistory ()
 500 {
 501   symbols = scm_make_weak_key_hash_table (scm_from_int (2139));
 502 }
 503
 504
 505 void
 506 scm_init_symbols ()
 507 {
 508 #include "libguile/symbols.x"
 509
 510   default_gensym_prefix = scm_from_latin1_string (" g");
 511 }
 512
 513 /*
 514   Local Variables:
 515   c-file-style: "gnu"
 516   End:
 517 */