| 1 | /* srfi-1.c --- SRFI-1 procedures for Guile |
| 2 | * |
| 3 | * Copyright (C) 1995, 1996, 1997, 2000, 2001, 2002, 2003, 2005, 2006, |
| 4 | * 2008, 2009, 2010, 2011 Free Software Foundation, Inc. |
| 5 | * |
| 6 | * This library is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU Lesser General Public License |
| 8 | * as published by the Free Software Foundation; either version 3 of |
| 9 | * the License, or (at your option) any later version. |
| 10 | * |
| 11 | * This library is distributed in the hope that it will be useful, but |
| 12 | * WITHOUT ANY WARRANTY; without even the implied warranty of |
| 13 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 14 | * Lesser General Public License for more details. |
| 15 | * |
| 16 | * You should have received a copy of the GNU Lesser General Public |
| 17 | * License along with this library; if not, write to the Free Software |
| 18 | * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 19 | * 02110-1301 USA |
| 20 | */ |
| 21 | |
| 22 | \f |
| 23 | #ifdef HAVE_CONFIG_H |
| 24 | # include <config.h> |
| 25 | #endif |
| 26 | |
| 27 | #include "libguile/_scm.h" |
| 28 | #include "libguile/eq.h" |
| 29 | |
| 30 | #include "libguile/validate.h" |
| 31 | #include "libguile/list.h" |
| 32 | #include "libguile/eval.h" |
| 33 | #include "libguile/srfi-1.h" |
| 34 | |
| 35 | #include <stdarg.h> |
| 36 | |
| 37 | |
| 38 | /* The intent of this file was to gradually replace those Scheme |
| 39 | * procedures in srfi-1.scm that extend core primitive procedures, |
| 40 | * so that using srfi-1 wouldn't have performance penalties. |
| 41 | * |
| 42 | * However, we now prefer to write these procedures in Scheme, let the compiler |
| 43 | * optimize them, and have the VM execute them efficiently. |
| 44 | */ |
| 45 | |
| 46 | |
| 47 | static SCM |
| 48 | equal_trampoline (SCM proc, SCM arg1, SCM arg2) |
| 49 | { |
| 50 | return scm_equal_p (arg1, arg2); |
| 51 | } |
| 52 | |
| 53 | /* list_copy_part() copies the first COUNT cells of LST, puts the result at |
| 54 | *dst, and returns the SCM_CDRLOC of the last cell in that new list. |
| 55 | |
| 56 | This function is designed to be careful about LST possibly having changed |
| 57 | in between the caller deciding what to copy, and the copy actually being |
| 58 | done here. The COUNT ensures we terminate if LST has become circular, |
| 59 | SCM_VALIDATE_CONS guards against a cdr in the list changed to some |
| 60 | non-pair object. */ |
| 61 | |
| 62 | #include <stdio.h> |
| 63 | static SCM * |
| 64 | list_copy_part (SCM lst, int count, SCM *dst) |
| 65 | #define FUNC_NAME "list_copy_part" |
| 66 | { |
| 67 | SCM c; |
| 68 | for ( ; count > 0; count--) |
| 69 | { |
| 70 | SCM_VALIDATE_CONS (SCM_ARGn, lst); |
| 71 | c = scm_cons (SCM_CAR (lst), SCM_EOL); |
| 72 | *dst = c; |
| 73 | dst = SCM_CDRLOC (c); |
| 74 | lst = SCM_CDR (lst); |
| 75 | } |
| 76 | return dst; |
| 77 | } |
| 78 | #undef FUNC_NAME |
| 79 | |
| 80 | |
| 81 | SCM_DEFINE (scm_srfi1_append_reverse, "append-reverse", 2, 0, 0, |
| 82 | (SCM revhead, SCM tail), |
| 83 | "Reverse @var{rev-head}, append @var{tail} to it, and return the\n" |
| 84 | "result. This is equivalent to @code{(append (reverse\n" |
| 85 | "@var{rev-head}) @var{tail})}, but its implementation is more\n" |
| 86 | "efficient.\n" |
| 87 | "\n" |
| 88 | "@example\n" |
| 89 | "(append-reverse '(1 2 3) '(4 5 6)) @result{} (3 2 1 4 5 6)\n" |
| 90 | "@end example") |
| 91 | #define FUNC_NAME s_scm_srfi1_append_reverse |
| 92 | { |
| 93 | while (scm_is_pair (revhead)) |
| 94 | { |
| 95 | /* copy first element of revhead onto front of tail */ |
| 96 | tail = scm_cons (SCM_CAR (revhead), tail); |
| 97 | revhead = SCM_CDR (revhead); |
| 98 | } |
| 99 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (revhead), revhead, SCM_ARG1, FUNC_NAME, |
| 100 | "list"); |
| 101 | return tail; |
| 102 | } |
| 103 | #undef FUNC_NAME |
| 104 | |
| 105 | |
| 106 | SCM_DEFINE (scm_srfi1_append_reverse_x, "append-reverse!", 2, 0, 0, |
| 107 | (SCM revhead, SCM tail), |
| 108 | "Reverse @var{rev-head}, append @var{tail} to it, and return the\n" |
| 109 | "result. This is equivalent to @code{(append! (reverse!\n" |
| 110 | "@var{rev-head}) @var{tail})}, but its implementation is more\n" |
| 111 | "efficient.\n" |
| 112 | "\n" |
| 113 | "@example\n" |
| 114 | "(append-reverse! (list 1 2 3) '(4 5 6)) @result{} (3 2 1 4 5 6)\n" |
| 115 | "@end example\n" |
| 116 | "\n" |
| 117 | "@var{rev-head} may be modified in order to produce the result.") |
| 118 | #define FUNC_NAME s_scm_srfi1_append_reverse_x |
| 119 | { |
| 120 | SCM newtail; |
| 121 | |
| 122 | while (scm_is_pair (revhead)) |
| 123 | { |
| 124 | /* take the first cons cell from revhead */ |
| 125 | newtail = revhead; |
| 126 | revhead = SCM_CDR (revhead); |
| 127 | |
| 128 | /* make it the new start of tail, appending the previous */ |
| 129 | SCM_SETCDR (newtail, tail); |
| 130 | tail = newtail; |
| 131 | } |
| 132 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (revhead), revhead, SCM_ARG1, FUNC_NAME, |
| 133 | "list"); |
| 134 | return tail; |
| 135 | } |
| 136 | #undef FUNC_NAME |
| 137 | |
| 138 | SCM_DEFINE (scm_srfi1_concatenate, "concatenate", 1, 0, 0, |
| 139 | (SCM lstlst), |
| 140 | "Construct a list by appending all lists in @var{lstlst}.\n" |
| 141 | "\n" |
| 142 | "@code{concatenate} is the same as @code{(apply append\n" |
| 143 | "@var{lstlst})}. It exists because some Scheme implementations\n" |
| 144 | "have a limit on the number of arguments a function takes, which\n" |
| 145 | "the @code{apply} might exceed. In Guile there is no such\n" |
| 146 | "limit.") |
| 147 | #define FUNC_NAME s_scm_srfi1_concatenate |
| 148 | { |
| 149 | SCM_VALIDATE_LIST (SCM_ARG1, lstlst); |
| 150 | return scm_append (lstlst); |
| 151 | } |
| 152 | #undef FUNC_NAME |
| 153 | |
| 154 | |
| 155 | SCM_DEFINE (scm_srfi1_concatenate_x, "concatenate!", 1, 0, 0, |
| 156 | (SCM lstlst), |
| 157 | "Construct a list by appending all lists in @var{lstlst}. Those\n" |
| 158 | "lists may be modified to produce the result.\n" |
| 159 | "\n" |
| 160 | "@code{concatenate!} is the same as @code{(apply append!\n" |
| 161 | "@var{lstlst})}. It exists because some Scheme implementations\n" |
| 162 | "have a limit on the number of arguments a function takes, which\n" |
| 163 | "the @code{apply} might exceed. In Guile there is no such\n" |
| 164 | "limit.") |
| 165 | #define FUNC_NAME s_scm_srfi1_concatenate_x |
| 166 | { |
| 167 | SCM_VALIDATE_LIST (SCM_ARG1, lstlst); |
| 168 | return scm_append_x (lstlst); |
| 169 | } |
| 170 | #undef FUNC_NAME |
| 171 | |
| 172 | |
| 173 | SCM_DEFINE (scm_srfi1_count, "count", 2, 0, 1, |
| 174 | (SCM pred, SCM list1, SCM rest), |
| 175 | "Return a count of the number of times @var{pred} returns true\n" |
| 176 | "when called on elements from the given lists.\n" |
| 177 | "\n" |
| 178 | "@var{pred} is called with @var{N} parameters @code{(@var{pred}\n" |
| 179 | "@var{elem1} @dots{} @var{elemN})}, each element being from the\n" |
| 180 | "corresponding @var{list1} @dots{} @var{lstN}. The first call is\n" |
| 181 | "with the first element of each list, the second with the second\n" |
| 182 | "element from each, and so on.\n" |
| 183 | "\n" |
| 184 | "Counting stops when the end of the shortest list is reached.\n" |
| 185 | "At least one list must be non-circular.") |
| 186 | #define FUNC_NAME s_scm_srfi1_count |
| 187 | { |
| 188 | long count; |
| 189 | SCM lst; |
| 190 | int argnum; |
| 191 | SCM_VALIDATE_REST_ARGUMENT (rest); |
| 192 | |
| 193 | count = 0; |
| 194 | |
| 195 | if (scm_is_null (rest)) |
| 196 | { |
| 197 | /* one list */ |
| 198 | SCM_ASSERT (scm_is_true (scm_procedure_p (pred)), pred, SCM_ARG1, FUNC_NAME); |
| 199 | |
| 200 | for ( ; scm_is_pair (list1); list1 = SCM_CDR (list1)) |
| 201 | count += scm_is_true (scm_call_1 (pred, SCM_CAR (list1))); |
| 202 | |
| 203 | /* check below that list1 is a proper list, and done */ |
| 204 | end_list1: |
| 205 | lst = list1; |
| 206 | argnum = 2; |
| 207 | } |
| 208 | else if (scm_is_pair (rest) && scm_is_null (SCM_CDR (rest))) |
| 209 | { |
| 210 | /* two lists */ |
| 211 | SCM list2; |
| 212 | |
| 213 | SCM_ASSERT (scm_is_true (scm_procedure_p (pred)), pred, SCM_ARG1, FUNC_NAME); |
| 214 | |
| 215 | list2 = SCM_CAR (rest); |
| 216 | for (;;) |
| 217 | { |
| 218 | if (! scm_is_pair (list1)) |
| 219 | goto end_list1; |
| 220 | if (! scm_is_pair (list2)) |
| 221 | { |
| 222 | lst = list2; |
| 223 | argnum = 3; |
| 224 | break; |
| 225 | } |
| 226 | count += scm_is_true (scm_call_2 |
| 227 | (pred, SCM_CAR (list1), SCM_CAR (list2))); |
| 228 | list1 = SCM_CDR (list1); |
| 229 | list2 = SCM_CDR (list2); |
| 230 | } |
| 231 | } |
| 232 | else |
| 233 | { |
| 234 | /* three or more lists */ |
| 235 | SCM vec, args, a; |
| 236 | size_t len, i; |
| 237 | |
| 238 | /* vec is the list arguments */ |
| 239 | vec = scm_vector (scm_cons (list1, rest)); |
| 240 | len = SCM_SIMPLE_VECTOR_LENGTH (vec); |
| 241 | |
| 242 | /* args is the argument list to pass to pred, same length as vec, |
| 243 | re-used for each call */ |
| 244 | args = scm_make_list (SCM_I_MAKINUM (len), SCM_UNDEFINED); |
| 245 | |
| 246 | for (;;) |
| 247 | { |
| 248 | /* first elem of each list in vec into args, and step those |
| 249 | vec entries onto their next element */ |
| 250 | for (i = 0, a = args, argnum = 2; |
| 251 | i < len; |
| 252 | i++, a = SCM_CDR (a), argnum++) |
| 253 | { |
| 254 | lst = SCM_SIMPLE_VECTOR_REF (vec, i); /* list argument */ |
| 255 | if (! scm_is_pair (lst)) |
| 256 | goto check_lst_and_done; |
| 257 | SCM_SETCAR (a, SCM_CAR (lst)); /* arg for pred */ |
| 258 | SCM_SIMPLE_VECTOR_SET (vec, i, SCM_CDR (lst)); /* rest of lst */ |
| 259 | } |
| 260 | |
| 261 | count += scm_is_true (scm_apply (pred, args, SCM_EOL)); |
| 262 | } |
| 263 | } |
| 264 | |
| 265 | check_lst_and_done: |
| 266 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, argnum, FUNC_NAME, "list"); |
| 267 | return scm_from_long (count); |
| 268 | } |
| 269 | #undef FUNC_NAME |
| 270 | |
| 271 | |
| 272 | SCM_DEFINE (scm_srfi1_delete, "delete", 2, 1, 0, |
| 273 | (SCM x, SCM lst, SCM pred), |
| 274 | "Return a list containing the elements of @var{lst} but with\n" |
| 275 | "those equal to @var{x} deleted. The returned elements will be\n" |
| 276 | "in the same order as they were in @var{lst}.\n" |
| 277 | "\n" |
| 278 | "Equality is determined by @var{pred}, or @code{equal?} if not\n" |
| 279 | "given. An equality call is made just once for each element,\n" |
| 280 | "but the order in which the calls are made on the elements is\n" |
| 281 | "unspecified.\n" |
| 282 | "\n" |
| 283 | "The equality calls are always @code{(pred x elem)}, ie.@: the\n" |
| 284 | "given @var{x} is first. This means for instance elements\n" |
| 285 | "greater than 5 can be deleted with @code{(delete 5 lst <)}.\n" |
| 286 | "\n" |
| 287 | "@var{lst} is not modified, but the returned list might share a\n" |
| 288 | "common tail with @var{lst}.") |
| 289 | #define FUNC_NAME s_scm_srfi1_delete |
| 290 | { |
| 291 | SCM ret, *p, keeplst; |
| 292 | int count; |
| 293 | |
| 294 | if (SCM_UNBNDP (pred)) |
| 295 | return scm_delete (x, lst); |
| 296 | |
| 297 | SCM_ASSERT (scm_is_true (scm_procedure_p (pred)), pred, SCM_ARG3, FUNC_NAME); |
| 298 | |
| 299 | /* ret is the return list being constructed. p is where to append to it, |
| 300 | initially &ret then SCM_CDRLOC of the last pair. lst progresses as |
| 301 | elements are considered. |
| 302 | |
| 303 | Elements to be retained are not immediately copied, instead keeplst is |
| 304 | the last pair in lst which is to be retained but not yet copied, count |
| 305 | is how many from there are wanted. When there's no more deletions, *p |
| 306 | can be set to keeplst to share the remainder of the original lst. (The |
| 307 | entire original lst if there's no deletions at all.) */ |
| 308 | |
| 309 | keeplst = lst; |
| 310 | count = 0; |
| 311 | p = &ret; |
| 312 | |
| 313 | for ( ; scm_is_pair (lst); lst = SCM_CDR (lst)) |
| 314 | { |
| 315 | if (scm_is_true (scm_call_2 (pred, x, SCM_CAR (lst)))) |
| 316 | { |
| 317 | /* delete this element, so copy those at keeplst */ |
| 318 | p = list_copy_part (keeplst, count, p); |
| 319 | keeplst = SCM_CDR (lst); |
| 320 | count = 0; |
| 321 | } |
| 322 | else |
| 323 | { |
| 324 | /* keep this element */ |
| 325 | count++; |
| 326 | } |
| 327 | } |
| 328 | |
| 329 | /* final retained elements */ |
| 330 | *p = keeplst; |
| 331 | |
| 332 | /* demand that lst was a proper list */ |
| 333 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME, "list"); |
| 334 | |
| 335 | return ret; |
| 336 | } |
| 337 | #undef FUNC_NAME |
| 338 | |
| 339 | |
| 340 | SCM_DEFINE (scm_srfi1_delete_x, "delete!", 2, 1, 0, |
| 341 | (SCM x, SCM lst, SCM pred), |
| 342 | "Return a list containing the elements of @var{lst} but with\n" |
| 343 | "those equal to @var{x} deleted. The returned elements will be\n" |
| 344 | "in the same order as they were in @var{lst}.\n" |
| 345 | "\n" |
| 346 | "Equality is determined by @var{pred}, or @code{equal?} if not\n" |
| 347 | "given. An equality call is made just once for each element,\n" |
| 348 | "but the order in which the calls are made on the elements is\n" |
| 349 | "unspecified.\n" |
| 350 | "\n" |
| 351 | "The equality calls are always @code{(pred x elem)}, ie.@: the\n" |
| 352 | "given @var{x} is first. This means for instance elements\n" |
| 353 | "greater than 5 can be deleted with @code{(delete 5 lst <)}.\n" |
| 354 | "\n" |
| 355 | "@var{lst} may be modified to construct the returned list.") |
| 356 | #define FUNC_NAME s_scm_srfi1_delete_x |
| 357 | { |
| 358 | SCM walk; |
| 359 | SCM *prev; |
| 360 | |
| 361 | if (SCM_UNBNDP (pred)) |
| 362 | return scm_delete_x (x, lst); |
| 363 | |
| 364 | SCM_ASSERT (scm_is_true (scm_procedure_p (pred)), pred, SCM_ARG3, FUNC_NAME); |
| 365 | |
| 366 | for (prev = &lst, walk = lst; |
| 367 | scm_is_pair (walk); |
| 368 | walk = SCM_CDR (walk)) |
| 369 | { |
| 370 | if (scm_is_true (scm_call_2 (pred, x, SCM_CAR (walk)))) |
| 371 | *prev = SCM_CDR (walk); |
| 372 | else |
| 373 | prev = SCM_CDRLOC (walk); |
| 374 | } |
| 375 | |
| 376 | /* demand the input was a proper list */ |
| 377 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (walk), walk, SCM_ARG2, FUNC_NAME,"list"); |
| 378 | return lst; |
| 379 | } |
| 380 | #undef FUNC_NAME |
| 381 | |
| 382 | |
| 383 | SCM_DEFINE (scm_srfi1_delete_duplicates, "delete-duplicates", 1, 1, 0, |
| 384 | (SCM lst, SCM pred), |
| 385 | "Return a list containing the elements of @var{lst} but without\n" |
| 386 | "duplicates.\n" |
| 387 | "\n" |
| 388 | "When elements are equal, only the first in @var{lst} is\n" |
| 389 | "retained. Equal elements can be anywhere in @var{lst}, they\n" |
| 390 | "don't have to be adjacent. The returned list will have the\n" |
| 391 | "retained elements in the same order as they were in @var{lst}.\n" |
| 392 | "\n" |
| 393 | "Equality is determined by @var{pred}, or @code{equal?} if not\n" |
| 394 | "given. Calls @code{(pred x y)} are made with element @var{x}\n" |
| 395 | "being before @var{y} in @var{lst}. A call is made at most once\n" |
| 396 | "for each combination, but the sequence of the calls across the\n" |
| 397 | "elements is unspecified.\n" |
| 398 | "\n" |
| 399 | "@var{lst} is not modified, but the return might share a common\n" |
| 400 | "tail with @var{lst}.\n" |
| 401 | "\n" |
| 402 | "In the worst case, this is an @math{O(N^2)} algorithm because\n" |
| 403 | "it must check each element against all those preceding it. For\n" |
| 404 | "long lists it is more efficient to sort and then compare only\n" |
| 405 | "adjacent elements.") |
| 406 | #define FUNC_NAME s_scm_srfi1_delete_duplicates |
| 407 | { |
| 408 | scm_t_trampoline_2 equal_p; |
| 409 | SCM ret, *p, keeplst, item, l; |
| 410 | int count, i; |
| 411 | |
| 412 | /* ret is the new list constructed. p is where to append, initially &ret |
| 413 | then SCM_CDRLOC of the last pair. lst is advanced as each element is |
| 414 | considered. |
| 415 | |
| 416 | Elements retained are not immediately appended to ret, instead keeplst |
| 417 | is the last pair in lst which is to be kept but is not yet copied. |
| 418 | Initially this is the first pair of lst, since the first element is |
| 419 | always retained. |
| 420 | |
| 421 | *p is kept set to keeplst, so ret (inclusive) to lst (exclusive) is all |
| 422 | the elements retained, making the equality search loop easy. |
| 423 | |
| 424 | If an item must be deleted, elements from keeplst (inclusive) to lst |
| 425 | (exclusive) must be copied and appended to ret. When there's no more |
| 426 | deletions, *p is left set to keeplst, so ret shares structure with the |
| 427 | original lst. (ret will be the entire original lst if there are no |
| 428 | deletions.) */ |
| 429 | |
| 430 | /* skip to end if an empty list (or something invalid) */ |
| 431 | ret = SCM_EOL; |
| 432 | |
| 433 | if (SCM_UNBNDP (pred)) |
| 434 | equal_p = equal_trampoline; |
| 435 | else |
| 436 | { |
| 437 | SCM_VALIDATE_PROC (SCM_ARG2, pred); |
| 438 | equal_p = scm_call_2; |
| 439 | } |
| 440 | |
| 441 | keeplst = lst; |
| 442 | count = 0; |
| 443 | p = &ret; |
| 444 | |
| 445 | for ( ; scm_is_pair (lst); lst = SCM_CDR (lst)) |
| 446 | { |
| 447 | item = SCM_CAR (lst); |
| 448 | |
| 449 | /* look for item in "ret" list */ |
| 450 | for (l = ret; scm_is_pair (l); l = SCM_CDR (l)) |
| 451 | { |
| 452 | if (scm_is_true (equal_p (pred, SCM_CAR (l), item))) |
| 453 | { |
| 454 | /* "item" is a duplicate, so copy keeplst onto ret */ |
| 455 | duplicate: |
| 456 | p = list_copy_part (keeplst, count, p); |
| 457 | |
| 458 | keeplst = SCM_CDR (lst); /* elem after the one deleted */ |
| 459 | count = 0; |
| 460 | goto next_elem; |
| 461 | } |
| 462 | } |
| 463 | |
| 464 | /* look for item in "keeplst" list |
| 465 | be careful traversing, in case nasty code changed the cdrs */ |
| 466 | for (i = 0, l = keeplst; |
| 467 | i < count && scm_is_pair (l); |
| 468 | i++, l = SCM_CDR (l)) |
| 469 | if (scm_is_true (equal_p (pred, SCM_CAR (l), item))) |
| 470 | goto duplicate; |
| 471 | |
| 472 | /* keep this element */ |
| 473 | count++; |
| 474 | |
| 475 | next_elem: |
| 476 | ; |
| 477 | } |
| 478 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG1, FUNC_NAME, "list"); |
| 479 | |
| 480 | /* share tail of keeplst items */ |
| 481 | *p = keeplst; |
| 482 | |
| 483 | return ret; |
| 484 | } |
| 485 | #undef FUNC_NAME |
| 486 | |
| 487 | |
| 488 | SCM_DEFINE (scm_srfi1_delete_duplicates_x, "delete-duplicates!", 1, 1, 0, |
| 489 | (SCM lst, SCM pred), |
| 490 | "Return a list containing the elements of @var{lst} but without\n" |
| 491 | "duplicates.\n" |
| 492 | "\n" |
| 493 | "When elements are equal, only the first in @var{lst} is\n" |
| 494 | "retained. Equal elements can be anywhere in @var{lst}, they\n" |
| 495 | "don't have to be adjacent. The returned list will have the\n" |
| 496 | "retained elements in the same order as they were in @var{lst}.\n" |
| 497 | "\n" |
| 498 | "Equality is determined by @var{pred}, or @code{equal?} if not\n" |
| 499 | "given. Calls @code{(pred x y)} are made with element @var{x}\n" |
| 500 | "being before @var{y} in @var{lst}. A call is made at most once\n" |
| 501 | "for each combination, but the sequence of the calls across the\n" |
| 502 | "elements is unspecified.\n" |
| 503 | "\n" |
| 504 | "@var{lst} may be modified to construct the returned list.\n" |
| 505 | "\n" |
| 506 | "In the worst case, this is an @math{O(N^2)} algorithm because\n" |
| 507 | "it must check each element against all those preceding it. For\n" |
| 508 | "long lists it is more efficient to sort and then compare only\n" |
| 509 | "adjacent elements.") |
| 510 | #define FUNC_NAME s_scm_srfi1_delete_duplicates_x |
| 511 | { |
| 512 | scm_t_trampoline_2 equal_p; |
| 513 | SCM ret, endret, item, l; |
| 514 | |
| 515 | /* ret is the return list, constructed from the pairs in lst. endret is |
| 516 | the last pair of ret, initially the first pair. lst is advanced as |
| 517 | elements are considered. */ |
| 518 | |
| 519 | /* skip to end if an empty list (or something invalid) */ |
| 520 | ret = lst; |
| 521 | if (scm_is_pair (lst)) |
| 522 | { |
| 523 | if (SCM_UNBNDP (pred)) |
| 524 | equal_p = equal_trampoline; |
| 525 | else |
| 526 | { |
| 527 | SCM_VALIDATE_PROC (SCM_ARG2, pred); |
| 528 | equal_p = scm_call_2; |
| 529 | } |
| 530 | |
| 531 | endret = ret; |
| 532 | |
| 533 | /* loop over lst elements starting from second */ |
| 534 | for (;;) |
| 535 | { |
| 536 | lst = SCM_CDR (lst); |
| 537 | if (! scm_is_pair (lst)) |
| 538 | break; |
| 539 | item = SCM_CAR (lst); |
| 540 | |
| 541 | /* is item equal to any element from ret to endret (inclusive)? */ |
| 542 | l = ret; |
| 543 | for (;;) |
| 544 | { |
| 545 | if (scm_is_true (equal_p (pred, SCM_CAR (l), item))) |
| 546 | break; /* equal, forget this element */ |
| 547 | |
| 548 | if (scm_is_eq (l, endret)) |
| 549 | { |
| 550 | /* not equal to any, so append this pair */ |
| 551 | SCM_SETCDR (endret, lst); |
| 552 | endret = lst; |
| 553 | break; |
| 554 | } |
| 555 | l = SCM_CDR (l); |
| 556 | } |
| 557 | } |
| 558 | |
| 559 | /* terminate, in case last element was deleted */ |
| 560 | SCM_SETCDR (endret, SCM_EOL); |
| 561 | } |
| 562 | |
| 563 | /* demand that lst was a proper list */ |
| 564 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG1, FUNC_NAME, "list"); |
| 565 | |
| 566 | return ret; |
| 567 | } |
| 568 | #undef FUNC_NAME |
| 569 | |
| 570 | |
| 571 | SCM_DEFINE (scm_srfi1_find, "find", 2, 0, 0, |
| 572 | (SCM pred, SCM lst), |
| 573 | "Return the first element of @var{lst} which satisfies the\n" |
| 574 | "predicate @var{pred}, or return @code{#f} if no such element is\n" |
| 575 | "found.") |
| 576 | #define FUNC_NAME s_scm_srfi1_find |
| 577 | { |
| 578 | SCM_VALIDATE_PROC (SCM_ARG1, pred); |
| 579 | |
| 580 | for ( ; scm_is_pair (lst); lst = SCM_CDR (lst)) |
| 581 | { |
| 582 | SCM elem = SCM_CAR (lst); |
| 583 | if (scm_is_true (scm_call_1 (pred, elem))) |
| 584 | return elem; |
| 585 | } |
| 586 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME, "list"); |
| 587 | |
| 588 | return SCM_BOOL_F; |
| 589 | } |
| 590 | #undef FUNC_NAME |
| 591 | |
| 592 | |
| 593 | SCM_DEFINE (scm_srfi1_find_tail, "find-tail", 2, 0, 0, |
| 594 | (SCM pred, SCM lst), |
| 595 | "Return the first pair of @var{lst} whose @sc{car} satisfies the\n" |
| 596 | "predicate @var{pred}, or return @code{#f} if no such element is\n" |
| 597 | "found.") |
| 598 | #define FUNC_NAME s_scm_srfi1_find_tail |
| 599 | { |
| 600 | SCM_VALIDATE_PROC (SCM_ARG1, pred); |
| 601 | |
| 602 | for ( ; scm_is_pair (lst); lst = SCM_CDR (lst)) |
| 603 | if (scm_is_true (scm_call_1 (pred, SCM_CAR (lst)))) |
| 604 | return lst; |
| 605 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME, "list"); |
| 606 | |
| 607 | return SCM_BOOL_F; |
| 608 | } |
| 609 | #undef FUNC_NAME |
| 610 | |
| 611 | SCM_DEFINE (scm_srfi1_length_plus, "length+", 1, 0, 0, |
| 612 | (SCM lst), |
| 613 | "Return the length of @var{lst}, or @code{#f} if @var{lst} is\n" |
| 614 | "circular.") |
| 615 | #define FUNC_NAME s_scm_srfi1_length_plus |
| 616 | { |
| 617 | long len = scm_ilength (lst); |
| 618 | return (len >= 0 ? SCM_I_MAKINUM (len) : SCM_BOOL_F); |
| 619 | } |
| 620 | #undef FUNC_NAME |
| 621 | |
| 622 | |
| 623 | /* This routine differs from the core list-copy in allowing improper lists. |
| 624 | Maybe the core could allow them similarly. */ |
| 625 | |
| 626 | SCM_DEFINE (scm_srfi1_list_copy, "list-copy", 1, 0, 0, |
| 627 | (SCM lst), |
| 628 | "Return a copy of the given list @var{lst}.\n" |
| 629 | "\n" |
| 630 | "@var{lst} can be a proper or improper list. And if @var{lst}\n" |
| 631 | "is not a pair then it's treated as the final tail of an\n" |
| 632 | "improper list and simply returned.") |
| 633 | #define FUNC_NAME s_scm_srfi1_list_copy |
| 634 | { |
| 635 | SCM newlst; |
| 636 | SCM * fill_here; |
| 637 | SCM from_here; |
| 638 | |
| 639 | newlst = lst; |
| 640 | fill_here = &newlst; |
| 641 | from_here = lst; |
| 642 | |
| 643 | while (scm_is_pair (from_here)) |
| 644 | { |
| 645 | SCM c; |
| 646 | c = scm_cons (SCM_CAR (from_here), SCM_CDR (from_here)); |
| 647 | *fill_here = c; |
| 648 | fill_here = SCM_CDRLOC (c); |
| 649 | from_here = SCM_CDR (from_here); |
| 650 | } |
| 651 | return newlst; |
| 652 | } |
| 653 | #undef FUNC_NAME |
| 654 | |
| 655 | SCM_DEFINE (scm_srfi1_lset_difference_x, "lset-difference!", 2, 0, 1, |
| 656 | (SCM equal, SCM lst, SCM rest), |
| 657 | "Return @var{lst} with any elements in the lists in @var{rest}\n" |
| 658 | "removed (ie.@: subtracted). For only one @var{lst} argument,\n" |
| 659 | "just that list is returned.\n" |
| 660 | "\n" |
| 661 | "The given @var{equal} procedure is used for comparing elements,\n" |
| 662 | "called as @code{(@var{equal} elem1 elemN)}. The first argument\n" |
| 663 | "is from @var{lst} and the second from one of the subsequent\n" |
| 664 | "lists. But exactly which calls are made and in what order is\n" |
| 665 | "unspecified.\n" |
| 666 | "\n" |
| 667 | "@example\n" |
| 668 | "(lset-difference! eqv? (list 'x 'y)) @result{} (x y)\n" |
| 669 | "(lset-difference! eqv? (list 1 2 3) '(3 1)) @result{} (2)\n" |
| 670 | "(lset-difference! eqv? (list 1 2 3) '(3) '(2)) @result{} (1)\n" |
| 671 | "@end example\n" |
| 672 | "\n" |
| 673 | "@code{lset-difference!} may modify @var{lst} to form its\n" |
| 674 | "result.") |
| 675 | #define FUNC_NAME s_scm_srfi1_lset_difference_x |
| 676 | { |
| 677 | SCM ret, *pos, elem, r, b; |
| 678 | int argnum; |
| 679 | |
| 680 | SCM_VALIDATE_PROC (SCM_ARG1, equal); |
| 681 | SCM_VALIDATE_REST_ARGUMENT (rest); |
| 682 | |
| 683 | ret = SCM_EOL; |
| 684 | pos = &ret; |
| 685 | for ( ; scm_is_pair (lst); lst = SCM_CDR (lst)) |
| 686 | { |
| 687 | elem = SCM_CAR (lst); |
| 688 | |
| 689 | for (r = rest, argnum = SCM_ARG3; |
| 690 | scm_is_pair (r); |
| 691 | r = SCM_CDR (r), argnum++) |
| 692 | { |
| 693 | for (b = SCM_CAR (r); scm_is_pair (b); b = SCM_CDR (b)) |
| 694 | if (scm_is_true (scm_call_2 (equal, elem, SCM_CAR (b)))) |
| 695 | goto next_elem; /* equal to elem, so drop that elem */ |
| 696 | |
| 697 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (b), b, argnum, FUNC_NAME,"list"); |
| 698 | } |
| 699 | |
| 700 | /* elem not equal to anything in later lists, so keep it */ |
| 701 | *pos = lst; |
| 702 | pos = SCM_CDRLOC (lst); |
| 703 | |
| 704 | next_elem: |
| 705 | ; |
| 706 | } |
| 707 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME, "list"); |
| 708 | |
| 709 | *pos = SCM_EOL; |
| 710 | return ret; |
| 711 | } |
| 712 | #undef FUNC_NAME |
| 713 | |
| 714 | |
| 715 | SCM_DEFINE (scm_srfi1_assoc, "assoc", 2, 1, 0, |
| 716 | (SCM key, SCM alist, SCM pred), |
| 717 | "Behaves like @code{assq} but uses third argument @var{pred}\n" |
| 718 | "for key comparison. If @var{pred} is not supplied,\n" |
| 719 | "@code{equal?} is used. (Extended from R5RS.)\n") |
| 720 | #define FUNC_NAME s_scm_srfi1_assoc |
| 721 | { |
| 722 | SCM ls = alist; |
| 723 | scm_t_trampoline_2 equal_p; |
| 724 | if (SCM_UNBNDP (pred)) |
| 725 | equal_p = equal_trampoline; |
| 726 | else |
| 727 | { |
| 728 | SCM_VALIDATE_PROC (SCM_ARG3, pred); |
| 729 | equal_p = scm_call_2; |
| 730 | } |
| 731 | for(; scm_is_pair (ls); ls = SCM_CDR (ls)) |
| 732 | { |
| 733 | SCM tmp = SCM_CAR (ls); |
| 734 | SCM_ASSERT_TYPE (scm_is_pair (tmp), alist, SCM_ARG2, FUNC_NAME, |
| 735 | "association list"); |
| 736 | if (scm_is_true (equal_p (pred, key, SCM_CAR (tmp)))) |
| 737 | return tmp; |
| 738 | } |
| 739 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (ls), alist, SCM_ARG2, FUNC_NAME, |
| 740 | "association list"); |
| 741 | return SCM_BOOL_F; |
| 742 | } |
| 743 | #undef FUNC_NAME |
| 744 | |
| 745 | SCM_DEFINE (scm_srfi1_partition, "partition", 2, 0, 0, |
| 746 | (SCM pred, SCM list), |
| 747 | "Partition the elements of @var{list} with predicate @var{pred}.\n" |
| 748 | "Return two values: the list of elements satisfying @var{pred} and\n" |
| 749 | "the list of elements @emph{not} satisfying @var{pred}. The order\n" |
| 750 | "of the output lists follows the order of @var{list}. @var{list}\n" |
| 751 | "is not mutated. One of the output lists may share memory with @var{list}.\n") |
| 752 | #define FUNC_NAME s_scm_srfi1_partition |
| 753 | { |
| 754 | /* In this implementation, the output lists don't share memory with |
| 755 | list, because it's probably not worth the effort. */ |
| 756 | SCM orig_list = list; |
| 757 | SCM kept = scm_cons(SCM_EOL, SCM_EOL); |
| 758 | SCM kept_tail = kept; |
| 759 | SCM dropped = scm_cons(SCM_EOL, SCM_EOL); |
| 760 | SCM dropped_tail = dropped; |
| 761 | |
| 762 | SCM_VALIDATE_PROC (SCM_ARG1, pred); |
| 763 | |
| 764 | for (; !SCM_NULL_OR_NIL_P (list); list = SCM_CDR(list)) { |
| 765 | SCM elt, new_tail; |
| 766 | |
| 767 | /* Make sure LIST is not a dotted list. */ |
| 768 | SCM_ASSERT (scm_is_pair (list), orig_list, SCM_ARG2, FUNC_NAME); |
| 769 | |
| 770 | elt = SCM_CAR (list); |
| 771 | new_tail = scm_cons (SCM_CAR (list), SCM_EOL); |
| 772 | |
| 773 | if (scm_is_true (scm_call_1 (pred, elt))) { |
| 774 | SCM_SETCDR(kept_tail, new_tail); |
| 775 | kept_tail = new_tail; |
| 776 | } |
| 777 | else { |
| 778 | SCM_SETCDR(dropped_tail, new_tail); |
| 779 | dropped_tail = new_tail; |
| 780 | } |
| 781 | } |
| 782 | /* re-use the initial conses for the values list */ |
| 783 | SCM_SETCAR(kept, SCM_CDR(kept)); |
| 784 | SCM_SETCDR(kept, dropped); |
| 785 | SCM_SETCAR(dropped, SCM_CDR(dropped)); |
| 786 | SCM_SETCDR(dropped, SCM_EOL); |
| 787 | return scm_values(kept); |
| 788 | } |
| 789 | #undef FUNC_NAME |
| 790 | |
| 791 | |
| 792 | SCM_DEFINE (scm_srfi1_partition_x, "partition!", 2, 0, 0, |
| 793 | (SCM pred, SCM lst), |
| 794 | "Split @var{lst} into those elements which do and don't satisfy\n" |
| 795 | "the predicate @var{pred}.\n" |
| 796 | "\n" |
| 797 | "The return is two values (@pxref{Multiple Values}), the first\n" |
| 798 | "being a list of all elements from @var{lst} which satisfy\n" |
| 799 | "@var{pred}, the second a list of those which do not.\n" |
| 800 | "\n" |
| 801 | "The elements in the result lists are in the same order as in\n" |
| 802 | "@var{lst} but the order in which the calls @code{(@var{pred}\n" |
| 803 | "elem)} are made on the list elements is unspecified.\n" |
| 804 | "\n" |
| 805 | "@var{lst} may be modified to construct the return lists.") |
| 806 | #define FUNC_NAME s_scm_srfi1_partition_x |
| 807 | { |
| 808 | SCM tlst, flst, *tp, *fp; |
| 809 | |
| 810 | SCM_ASSERT (scm_is_true (scm_procedure_p (pred)), pred, SCM_ARG1, FUNC_NAME); |
| 811 | |
| 812 | /* tlst and flst are the lists of true and false elements. tp and fp are |
| 813 | where to store to append to them, initially &tlst and &flst, then |
| 814 | SCM_CDRLOC of the last pair in the respective lists. */ |
| 815 | |
| 816 | tlst = SCM_EOL; |
| 817 | flst = SCM_EOL; |
| 818 | tp = &tlst; |
| 819 | fp = &flst; |
| 820 | |
| 821 | for ( ; scm_is_pair (lst); lst = SCM_CDR (lst)) |
| 822 | { |
| 823 | if (scm_is_true (scm_call_1 (pred, SCM_CAR (lst)))) |
| 824 | { |
| 825 | *tp = lst; |
| 826 | tp = SCM_CDRLOC (lst); |
| 827 | } |
| 828 | else |
| 829 | { |
| 830 | *fp = lst; |
| 831 | fp = SCM_CDRLOC (lst); |
| 832 | } |
| 833 | } |
| 834 | |
| 835 | SCM_ASSERT_TYPE (SCM_NULL_OR_NIL_P (lst), lst, SCM_ARG2, FUNC_NAME, "list"); |
| 836 | |
| 837 | /* terminate whichever didn't get the last element(s) */ |
| 838 | *tp = SCM_EOL; |
| 839 | *fp = SCM_EOL; |
| 840 | |
| 841 | return scm_values (scm_list_2 (tlst, flst)); |
| 842 | } |
| 843 | #undef FUNC_NAME |
| 844 | |
| 845 | SCM_DEFINE (scm_srfi1_remove, "remove", 2, 0, 0, |
| 846 | (SCM pred, SCM list), |
| 847 | "Return a list containing all elements from @var{list} which do\n" |
| 848 | "not satisfy the predicate @var{pred}. The elements in the\n" |
| 849 | "result list have the same order as in @var{list}. The order in\n" |
| 850 | "which @var{pred} is applied to the list elements is not\n" |
| 851 | "specified.") |
| 852 | #define FUNC_NAME s_scm_srfi1_remove |
| 853 | { |
| 854 | SCM walk; |
| 855 | SCM *prev; |
| 856 | SCM res = SCM_EOL; |
| 857 | SCM_VALIDATE_PROC (SCM_ARG1, pred); |
| 858 | SCM_VALIDATE_LIST (2, list); |
| 859 | |
| 860 | for (prev = &res, walk = list; |
| 861 | scm_is_pair (walk); |
| 862 | walk = SCM_CDR (walk)) |
| 863 | { |
| 864 | if (scm_is_false (scm_call_1 (pred, SCM_CAR (walk)))) |
| 865 | { |
| 866 | *prev = scm_cons (SCM_CAR (walk), SCM_EOL); |
| 867 | prev = SCM_CDRLOC (*prev); |
| 868 | } |
| 869 | } |
| 870 | |
| 871 | return res; |
| 872 | } |
| 873 | #undef FUNC_NAME |
| 874 | |
| 875 | |
| 876 | SCM_DEFINE (scm_srfi1_remove_x, "remove!", 2, 0, 0, |
| 877 | (SCM pred, SCM list), |
| 878 | "Return a list containing all elements from @var{list} which do\n" |
| 879 | "not satisfy the predicate @var{pred}. The elements in the\n" |
| 880 | "result list have the same order as in @var{list}. The order in\n" |
| 881 | "which @var{pred} is applied to the list elements is not\n" |
| 882 | "specified. @var{list} may be modified to build the return\n" |
| 883 | "list.") |
| 884 | #define FUNC_NAME s_scm_srfi1_remove_x |
| 885 | { |
| 886 | SCM walk; |
| 887 | SCM *prev; |
| 888 | SCM_VALIDATE_PROC (SCM_ARG1, pred); |
| 889 | SCM_VALIDATE_LIST (2, list); |
| 890 | |
| 891 | for (prev = &list, walk = list; |
| 892 | scm_is_pair (walk); |
| 893 | walk = SCM_CDR (walk)) |
| 894 | { |
| 895 | if (scm_is_false (scm_call_1 (pred, SCM_CAR (walk)))) |
| 896 | prev = SCM_CDRLOC (walk); |
| 897 | else |
| 898 | *prev = SCM_CDR (walk); |
| 899 | } |
| 900 | |
| 901 | return list; |
| 902 | } |
| 903 | #undef FUNC_NAME |
| 904 | |
| 905 | \f |
| 906 | void |
| 907 | scm_register_srfi_1 (void) |
| 908 | { |
| 909 | scm_c_register_extension ("libguile-" SCM_EFFECTIVE_VERSION, |
| 910 | "scm_init_srfi_1", |
| 911 | (scm_t_extension_init_func)scm_init_srfi_1, NULL); |
| 912 | } |
| 913 | |
| 914 | void |
| 915 | scm_init_srfi_1 (void) |
| 916 | { |
| 917 | #ifndef SCM_MAGIC_SNARFER |
| 918 | #include "libguile/srfi-1.x" |
| 919 | #endif |
| 920 | } |
| 921 | |
| 922 | /* End of srfi-1.c. */ |