libguile/read.c

   1 /* Copyright (C) 1995,1996,1997,1999,2000,2001 Free Software Foundation, Inc.
   2  *
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2, or (at your option)
   6  * any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this software; see the file COPYING.  If not, write to
  15  * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
  16  * Boston, MA 02111-1307 USA
  17  *
  18  * As a special exception, the Free Software Foundation gives permission
  19  * for additional uses of the text contained in its release of GUILE.
  20  *
  21  * The exception is that, if you link the GUILE library with other files
  22  * to produce an executable, this does not by itself cause the
  23  * resulting executable to be covered by the GNU General Public License.
  24  * Your use of that executable is in no way restricted on account of
  25  * linking the GUILE library code into it.
  26  *
  27  * This exception does not however invalidate any other reasons why
  28  * the executable file might be covered by the GNU General Public License.
  29  *
  30  * This exception applies only to the code released by the
  31  * Free Software Foundation under the name GUILE.  If you copy
  32  * code from other Free Software Foundation releases into a copy of
  33  * GUILE, as the General Public License permits, the exception does
  34  * not apply to the code that you add in this way.  To avoid misleading
  35  * anyone as to the status of such modified files, you must delete
  36  * this exception notice from them.
  37  *
  38  * If you write modifications of your own for GUILE, it is your choice
  39  * whether to permit this exception to apply to your modifications.
  40  * If you do not wish that, delete this exception notice.  */
  41
  42
  43 \f
  44
  45 #include <stdio.h>
  46 #include "libguile/_scm.h"
  47 #include "libguile/chars.h"
  48 #include "libguile/eval.h"
  49 #include "libguile/unif.h"
  50 #include "libguile/keywords.h"
  51 #include "libguile/alist.h"
  52 #include "libguile/srcprop.h"
  53 #include "libguile/hashtab.h"
  54 #include "libguile/hash.h"
  55 #include "libguile/ports.h"
  56 #include "libguile/root.h"
  57 #include "libguile/strings.h"
  58 #include "libguile/vectors.h"
  59
  60 #include "libguile/validate.h"
  61 #include "libguile/read.h"
  62
  63 \f
  64
  65 SCM_SYMBOL (scm_keyword_prefix, "prefix");
  66
  67 scm_t_option scm_read_opts[] = {
  68   { SCM_OPTION_BOOLEAN, "copy", 0,
  69     "Copy source code expressions." },
  70   { SCM_OPTION_BOOLEAN, "positions", 0,
  71     "Record positions of source code expressions." },
  72   { SCM_OPTION_BOOLEAN, "case-insensitive", 0,
  73     "Convert symbols to lower case."},
  74   { SCM_OPTION_SCM, "keywords", SCM_UNPACK (SCM_BOOL_F),
  75     "Style of keyword recognition: #f or 'prefix"}
  76 };
  77
  78 SCM_DEFINE (scm_read_options, "read-options-interface", 0, 1, 0,
  79             (SCM setting),
  80             "Option interface for the read options. Instead of using\n"
  81             "this procedure directly, use the procedures @code{read-enable},\n"
  82             "@code{read-disable}, @code{read-set!} and @var{read-options}.")
  83 #define FUNC_NAME s_scm_read_options
  84 {
  85   SCM ans = scm_options (setting,
  86                          scm_read_opts,
  87                          SCM_N_READ_OPTIONS,
  88                          FUNC_NAME);
  89   if (SCM_COPY_SOURCE_P)
  90     SCM_RECORD_POSITIONS_P = 1;
  91   return ans;
  92 }
  93 #undef FUNC_NAME
  94
  95 /* An association list mapping extra hash characters to procedures.  */
  96 static SCM *scm_read_hash_procedures;
  97
  98 SCM_DEFINE (scm_read, "read", 0, 1, 0,
  99             (SCM port),
 100             "Read an s-expression from the input port @var{port}, or from\n"
 101             "the current input port if @var{port} is not specified.\n"
 102             "Any whitespace before the next token is discarded.")
 103 #define FUNC_NAME s_scm_read
 104 {
 105   int c;
 106   SCM tok_buf, copy;
 107
 108   if (SCM_UNBNDP (port))
 109     port = scm_cur_inp;
 110   SCM_VALIDATE_OPINPORT (1,port);
 111
 112   c = scm_flush_ws (port, (char *) NULL);
 113   if (EOF == c)
 114     return SCM_EOF_VAL;
 115   scm_ungetc (c, port);
 116
 117   tok_buf = scm_allocate_string (30);
 118   return scm_lreadr (&tok_buf, port, &copy);
 119 }
 120 #undef FUNC_NAME
 121
 122
 123
 124 char *
 125 scm_grow_tok_buf (SCM *tok_buf)
 126 {
 127   size_t oldlen = SCM_STRING_LENGTH (*tok_buf);
 128   SCM newstr = scm_allocate_string (2 * oldlen);
 129   size_t i;
 130
 131   for (i = 0; i != oldlen; ++i)
 132     SCM_STRING_CHARS (newstr) [i] = SCM_STRING_CHARS (*tok_buf) [i];
 133
 134   *tok_buf = newstr;
 135   return SCM_STRING_CHARS (newstr);
 136 }
 137
 138
 139
 140 int
 141 scm_flush_ws (SCM port, const char *eoferr)
 142 {
 143   register int c;
 144   while (1)
 145     switch (c = scm_getc (port))
 146       {
 147       case EOF:
 148       goteof:
 149         if (eoferr)
 150           {
 151             if (!SCM_FALSEP (SCM_FILENAME (port)))
 152               scm_misc_error (eoferr,
 153                               "end of file in ~A",
 154                               scm_list_1 (SCM_FILENAME (port)));
 155             else
 156               scm_misc_error (eoferr, "end of file", SCM_EOL);
 157           }
 158         return c;
 159       case ';':
 160       lp:
 161         switch (c = scm_getc (port))
 162           {
 163           case EOF:
 164             goto goteof;
 165           default:
 166             goto lp;
 167           case SCM_LINE_INCREMENTORS:
 168             break;
 169           }
 170         break;
 171       case SCM_LINE_INCREMENTORS:
 172       case SCM_SINGLE_SPACES:
 173       case '\t':
 174         break;
 175       default:
 176         return c;
 177       }
 178 }
 179
 180
 181
 182 int
 183 scm_casei_streq (char *s1, char *s2)
 184 {
 185   while (*s1 && *s2)
 186     if (scm_downcase((int)*s1) != scm_downcase((int)*s2))
 187       return 0;
 188     else
 189       {
 190         ++s1;
 191         ++s2;
 192       }
 193   return !(*s1 || *s2);
 194 }
 195
 196
 197 /* recsexpr is used when recording expressions
 198  * constructed by read:sharp.
 199  */
 200 #ifndef DEBUG_EXTENSIONS
 201 #define recsexpr(obj, line, column, filename) (obj)
 202 #else
 203 static SCM
 204 recsexpr (SCM obj, long line, int column, SCM filename)
 205 {
 206   if (!SCM_CONSP(obj)) {
 207     return obj;
 208   } else {
 209     SCM tmp = obj, copy;
 210     /* If this sexpr is visible in the read:sharp source, we want to
 211        keep that information, so only record non-constant cons cells
 212        which haven't previously been read by the reader. */
 213     if (SCM_FALSEP (scm_whash_lookup (scm_source_whash, obj)))
 214       {
 215         if (SCM_COPY_SOURCE_P)
 216           {
 217             copy = scm_cons (recsexpr (SCM_CAR (obj), line, column, filename),
 218                              SCM_UNDEFINED);
 219             while ((tmp = SCM_CDR (tmp)) && SCM_CONSP (tmp))
 220               {
 221                 SCM_SETCDR (copy, scm_cons (recsexpr (SCM_CAR (tmp),
 222                                                       line,
 223                                                       column,
 224                                                       filename),
 225                                             SCM_UNDEFINED));
 226                 copy = SCM_CDR (copy);
 227               }
 228             SCM_SETCDR (copy, tmp);
 229           }
 230         else
 231           {
 232             recsexpr (SCM_CAR (obj), line, column, filename);
 233             while ((tmp = SCM_CDR (tmp)) && SCM_CONSP (tmp))
 234               recsexpr (SCM_CAR (tmp), line, column, filename);
 235             copy = SCM_UNDEFINED;
 236           }
 237         scm_whash_insert (scm_source_whash,
 238                           obj,
 239                           scm_make_srcprops (line,
 240                                              column,
 241                                              filename,
 242                                              copy,
 243                                              SCM_EOL));
 244       }
 245     return obj;
 246   }
 247 }
 248 #endif
 249
 250 /* Consume an SCSH-style block comment.  Assume that we've already
 251    read the initial `#!', and eat characters until we get a
 252    newline/exclamation-point/sharp-sign/newline sequence.  */
 253
 254 static void
 255 skip_scsh_block_comment (SCM port)
 256 #define FUNC_NAME "skip_scsh_block_comment"
 257 {
 258   /* Is this portable?  Dear God, spare me from the non-eight-bit
 259      characters.  But is it tasteful?  */
 260   long history = 0;
 261
 262   for (;;)
 263     {
 264       int c = scm_getc (port);
 265
 266       if (c == EOF)
 267         SCM_MISC_ERROR ("unterminated `#! ... !#' comment", SCM_EOL);
 268       history = ((history << 8) | (c & 0xff)) & 0xffffffff;
 269
 270       /* Were the last four characters read "\n!#\n"?  */
 271       if (history == (('\n' << 24) | ('!' << 16) | ('#' << 8) | '\n'))
 272         return;
 273     }
 274 }
 275 #undef FUNC_NAME
 276
 277
 278 static SCM scm_get_hash_procedure(int c);
 279
 280 static char s_list[]="list";
 281
 282 SCM
 283 scm_lreadr (SCM *tok_buf,SCM port,SCM *copy)
 284 #define FUNC_NAME "scm_lreadr"
 285 {
 286   int c;
 287   size_t j;
 288   SCM p;
 289
 290  tryagain:
 291   c = scm_flush_ws (port, s_scm_read);
 292  tryagain_no_flush_ws:
 293   switch (c)
 294     {
 295     case EOF:
 296       return SCM_EOF_VAL;
 297
 298     case '(':
 299       return SCM_RECORD_POSITIONS_P
 300         ? scm_lreadrecparen (tok_buf, port, s_list, copy)
 301         : scm_lreadparen (tok_buf, port, s_list, copy);
 302     case ')':
 303       SCM_MISC_ERROR ("unexpected \")\"", SCM_EOL);
 304       goto tryagain;
 305
 306     case '\'':
 307       p = scm_sym_quote;
 308       goto recquote;
 309     case '`':
 310       p = scm_sym_quasiquote;
 311       goto recquote;
 312     case ',':
 313       c = scm_getc (port);
 314       if ('@' == c)
 315         p = scm_sym_uq_splicing;
 316       else
 317         {
 318           scm_ungetc (c, port);
 319           p = scm_sym_unquote;
 320         }
 321     recquote:
 322       p = scm_cons2 (p,
 323                      scm_lreadr (tok_buf, port, copy),
 324                      SCM_EOL);
 325       if (SCM_RECORD_POSITIONS_P)
 326         scm_whash_insert (scm_source_whash,
 327                           p,
 328                           scm_make_srcprops (SCM_LINUM (port),
 329                                              SCM_COL (port) - 1,
 330                                              SCM_FILENAME (port),
 331                                              SCM_COPY_SOURCE_P
 332                                              ? (*copy = scm_cons2 (SCM_CAR (p),
 333                                                                    SCM_CAR (SCM_CDR (p)),
 334                                                                    SCM_EOL))
 335                                              : SCM_UNDEFINED,
 336                                              SCM_EOL));
 337       return p;
 338     case '#':
 339       c = scm_getc (port);
 340
 341       {
 342         /* Check for user-defined hash procedure first, to allow
 343            overriding of builtin hash read syntaxes.  */
 344         SCM sharp = scm_get_hash_procedure (c);
 345         if (!SCM_FALSEP (sharp))
 346           {
 347             int line = SCM_LINUM (port);
 348             int column = SCM_COL (port) - 2;
 349             SCM got;
 350
 351             got = scm_call_2 (sharp, SCM_MAKE_CHAR (c), port);
 352             if (SCM_EQ_P (got, SCM_UNSPECIFIED))
 353               goto unkshrp;
 354             if (SCM_RECORD_POSITIONS_P)
 355               return *copy = recsexpr (got, line, column,
 356                                        SCM_FILENAME (port));
 357             else
 358               return got;
 359           }
 360       }
 361       switch (c)
 362         {
 363         case '(':
 364           p = scm_lreadparen (tok_buf, port, "vector", copy);
 365           return SCM_NULLP (p) ? scm_nullvect : scm_vector (p);
 366
 367         case 't':
 368         case 'T':
 369           return SCM_BOOL_T;
 370         case 'f':
 371         case 'F':
 372           return SCM_BOOL_F;
 373
 374         case 'b':
 375         case 'B':
 376         case 'o':
 377         case 'O':
 378         case 'd':
 379         case 'D':
 380         case 'x':
 381         case 'X':
 382         case 'i':
 383         case 'I':
 384         case 'e':
 385         case 'E':
 386           scm_ungetc (c, port);
 387           c = '#';
 388           goto num;
 389
 390         case '!':
 391           /* start of a shell script.  Parse as a block comment,
 392              terminated by !#, just like SCSH.  */
 393           skip_scsh_block_comment (port);
 394           /* EOF is not an error here */
 395           c = scm_flush_ws (port, (char *)NULL);
 396           goto tryagain_no_flush_ws;
 397
 398 #ifdef HAVE_ARRAYS
 399         case '*':
 400           j = scm_read_token (c, tok_buf, port, 0);
 401           p = scm_istr2bve (SCM_STRING_CHARS (*tok_buf) + 1, (long) (j - 1));
 402           if (!SCM_FALSEP (p))
 403             return p;
 404           else
 405             goto unkshrp;
 406 #endif
 407
 408         case '{':
 409           j = scm_read_token (c, tok_buf, port, 1);
 410           return scm_mem2symbol (SCM_STRING_CHARS (*tok_buf), j);
 411
 412         case '\\':
 413           c = scm_getc (port);
 414           j = scm_read_token (c, tok_buf, port, 0);
 415           if (j == 1)
 416             return SCM_MAKE_CHAR (c);
 417           if (c >= '0' && c < '8')
 418             {
 419               /* Dirk:FIXME::  This type of character syntax is not R5RS
 420                * compliant.  Further, it should be verified that the constant
 421                * does only consist of octal digits.  Finally, it should be
 422                * checked whether the resulting fixnum is in the range of
 423                * characters.  */
 424               p = scm_i_mem2number (SCM_STRING_CHARS (*tok_buf), j, 8);
 425               if (SCM_INUMP (p))
 426                 return SCM_MAKE_CHAR (SCM_INUM (p));
 427             }
 428           for (c = 0; c < scm_n_charnames; c++)
 429             if (scm_charnames[c]
 430                 && (scm_casei_streq (scm_charnames[c], SCM_STRING_CHARS (*tok_buf))))
 431               return SCM_MAKE_CHAR (scm_charnums[c]);
 432           SCM_MISC_ERROR ("unknown # object", SCM_EOL);
 433
 434           /* #:SYMBOL is a syntax for keywords supported in all contexts.  */
 435         case ':':
 436           j = scm_read_token ('-', tok_buf, port, 0);
 437           p = scm_mem2symbol (SCM_STRING_CHARS (*tok_buf), j);
 438           return scm_make_keyword_from_dash_symbol (p);
 439
 440         default:
 441         callshrp:
 442           {
 443             SCM sharp = scm_get_hash_procedure (c);
 444
 445             if (!SCM_FALSEP (sharp))
 446               {
 447                 int line = SCM_LINUM (port);
 448                 int column = SCM_COL (port) - 2;
 449                 SCM got;
 450
 451                 got = scm_call_2 (sharp, SCM_MAKE_CHAR (c), port);
 452                 if (SCM_EQ_P (got, SCM_UNSPECIFIED))
 453                   goto unkshrp;
 454                 if (SCM_RECORD_POSITIONS_P)
 455                   return *copy = recsexpr (got, line, column,
 456                                            SCM_FILENAME (port));
 457                 else
 458                   return got;
 459               }
 460           }
 461         unkshrp:
 462         scm_misc_error (s_scm_read, "Unknown # object: ~S",
 463                         scm_list_1 (SCM_MAKE_CHAR (c)));
 464         }
 465
 466     case '"':
 467       j = 0;
 468       while ('"' != (c = scm_getc (port)))
 469         {
 470           if (c == EOF)
 471             SCM_MISC_ERROR ("end of file in string constant", SCM_EOL);
 472
 473           while (j + 2 >= SCM_STRING_LENGTH (*tok_buf))
 474             scm_grow_tok_buf (tok_buf);
 475
 476           if (c == '\\')
 477             switch (c = scm_getc (port))
 478               {
 479               case '\n':
 480                 continue;
 481               case '0':
 482                 c = '\0';
 483                 break;
 484               case 'f':
 485                 c = '\f';
 486                 break;
 487               case 'n':
 488                 c = '\n';
 489                 break;
 490               case 'r':
 491                 c = '\r';
 492                 break;
 493               case 't':
 494                 c = '\t';
 495                 break;
 496               case 'a':
 497                 c = '\007';
 498                 break;
 499               case 'v':
 500                 c = '\v';
 501                 break;
 502               }
 503           SCM_STRING_CHARS (*tok_buf)[j] = c;
 504           ++j;
 505         }
 506       if (j == 0)
 507         return scm_nullstr;
 508       SCM_STRING_CHARS (*tok_buf)[j] = 0;
 509       return scm_mem2string (SCM_STRING_CHARS (*tok_buf), j);
 510
 511     case '0': case '1': case '2': case '3': case '4':
 512     case '5': case '6': case '7': case '8': case '9':
 513     case '.':
 514     case '-':
 515     case '+':
 516     num:
 517       j = scm_read_token (c, tok_buf, port, 0);
 518       if (j == 1 && (c == '+' || c == '-'))
 519         /* Shortcut:  Detected symbol '+ or '- */
 520         goto tok;
 521
 522       p = scm_i_mem2number (SCM_STRING_CHARS (*tok_buf), j, 10);
 523       if (!SCM_FALSEP (p))
 524         return p;
 525       if (c == '#')
 526         {
 527           if ((j == 2) && (scm_getc (port) == '('))
 528             {
 529               scm_ungetc ('(', port);
 530               c = SCM_STRING_CHARS (*tok_buf)[1];
 531               goto callshrp;
 532             }
 533           SCM_MISC_ERROR ("unknown # object", SCM_EOL);
 534         }
 535       goto tok;
 536
 537     case ':':
 538       if (SCM_EQ_P (SCM_PACK (SCM_KEYWORD_STYLE), scm_keyword_prefix))
 539         {
 540           j = scm_read_token ('-', tok_buf, port, 0);
 541           p = scm_mem2symbol (SCM_STRING_CHARS (*tok_buf), j);
 542           return scm_make_keyword_from_dash_symbol (p);
 543         }
 544       /* fallthrough */
 545     default:
 546       j = scm_read_token (c, tok_buf, port, 0);
 547       /* fallthrough */
 548
 549     tok:
 550       return scm_mem2symbol (SCM_STRING_CHARS (*tok_buf), j);
 551     }
 552 }
 553 #undef FUNC_NAME
 554
 555
 556 #ifdef _UNICOS
 557 _Pragma ("noopt");              /* # pragma _CRI noopt */
 558 #endif
 559
 560 size_t
 561 scm_read_token (int ic, SCM *tok_buf, SCM port, int weird)
 562 {
 563   register size_t j;
 564   register int c;
 565   register char *p;
 566
 567   c = (SCM_CASE_INSENSITIVE_P ? scm_downcase(ic) : ic);
 568   p = SCM_STRING_CHARS (*tok_buf);
 569
 570   if (weird)
 571     j = 0;
 572   else
 573     {
 574       j = 0;
 575       while (j + 2 >= SCM_STRING_LENGTH (*tok_buf))
 576         p = scm_grow_tok_buf (tok_buf);
 577       p[j] = c;
 578       ++j;
 579     }
 580
 581   while (1)
 582     {
 583       while (j + 2 >= SCM_STRING_LENGTH (*tok_buf))
 584         p = scm_grow_tok_buf (tok_buf);
 585       c = scm_getc (port);
 586       switch (c)
 587         {
 588         case '(':
 589         case ')':
 590         case '"':
 591         case ';':
 592         case SCM_WHITE_SPACES:
 593         case SCM_LINE_INCREMENTORS:
 594           if (weird)
 595             goto default_case;
 596
 597           scm_ungetc (c, port);
 598         case EOF:
 599         eof_case:
 600           p[j] = 0;
 601           return j;
 602         case '\\':
 603           if (!weird)
 604             goto default_case;
 605           else
 606             {
 607               c = scm_getc (port);
 608               if (c == EOF)
 609                 goto eof_case;
 610               else
 611                 goto default_case;
 612             }
 613         case '}':
 614           if (!weird)
 615             goto default_case;
 616
 617           c = scm_getc (port);
 618           if (c == '#')
 619             {
 620               p[j] = 0;
 621               return j;
 622             }
 623           else
 624             {
 625               scm_ungetc (c, port);
 626               c = '}';
 627               goto default_case;
 628             }
 629
 630         default:
 631         default_case:
 632           {
 633             c = (SCM_CASE_INSENSITIVE_P ? scm_downcase(c) : c);
 634             p[j] = c;
 635             ++j;
 636           }
 637
 638         }
 639     }
 640 }
 641
 642 #ifdef _UNICOS
 643 _Pragma ("opt");                /* # pragma _CRI opt */
 644 #endif
 645
 646 SCM
 647 scm_lreadparen (SCM *tok_buf, SCM port, char *name, SCM *copy)
 648 #define FUNC_NAME "scm_lreadparen"
 649 {
 650   SCM tmp;
 651   SCM tl;
 652   SCM ans;
 653   int c;
 654
 655   c = scm_flush_ws (port, name);
 656   if (')' == c)
 657     return SCM_EOL;
 658   scm_ungetc (c, port);
 659   if (SCM_EQ_P (scm_sym_dot, (tmp = scm_lreadr (tok_buf, port, copy))))
 660     {
 661       ans = scm_lreadr (tok_buf, port, copy);
 662     closeit:
 663       if (')' != (c = scm_flush_ws (port, name)))
 664         SCM_MISC_ERROR ("missing close paren", SCM_EOL);
 665       return ans;
 666     }
 667   ans = tl = scm_cons (tmp, SCM_EOL);
 668   while (')' != (c = scm_flush_ws (port, name)))
 669     {
 670       scm_ungetc (c, port);
 671       if (SCM_EQ_P (scm_sym_dot, (tmp = scm_lreadr (tok_buf, port, copy))))
 672         {
 673           SCM_SETCDR (tl, scm_lreadr (tok_buf, port, copy));
 674           goto closeit;
 675         }
 676       SCM_SETCDR (tl, scm_cons (tmp, SCM_EOL));
 677       tl = SCM_CDR (tl);
 678     }
 679   return ans;
 680 }
 681 #undef FUNC_NAME
 682
 683
 684 SCM
 685 scm_lreadrecparen (SCM *tok_buf, SCM port, char *name, SCM *copy)
 686 #define FUNC_NAME "scm_lreadrecparen"
 687 {
 688   register int c;
 689   register SCM tmp;
 690   register SCM tl, tl2 = SCM_EOL;
 691   SCM ans, ans2 = SCM_EOL;
 692   /* Need to capture line and column numbers here. */
 693   int line = SCM_LINUM (port);
 694   int column = SCM_COL (port) - 1;
 695
 696   c = scm_flush_ws (port, name);
 697   if (')' == c)
 698     return SCM_EOL;
 699   scm_ungetc (c, port);
 700   if (SCM_EQ_P (scm_sym_dot, (tmp = scm_lreadr (tok_buf, port, copy))))
 701     {
 702       ans = scm_lreadr (tok_buf, port, copy);
 703       if (')' != (c = scm_flush_ws (port, name)))
 704         SCM_MISC_ERROR ("missing close paren", SCM_EOL);
 705       return ans;
 706     }
 707   /* Build the head of the list structure. */
 708   ans = tl = scm_cons (tmp, SCM_EOL);
 709   if (SCM_COPY_SOURCE_P)
 710     ans2 = tl2 = scm_cons (SCM_CONSP (tmp)
 711                            ? *copy
 712                            : tmp,
 713                            SCM_EOL);
 714   while (')' != (c = scm_flush_ws (port, name)))
 715     {
 716       SCM new_tail;
 717
 718       scm_ungetc (c, port);
 719       if (SCM_EQ_P (scm_sym_dot, (tmp = scm_lreadr (tok_buf, port, copy))))
 720         {
 721           SCM_SETCDR (tl, tmp = scm_lreadr (tok_buf, port, copy));
 722           if (SCM_COPY_SOURCE_P)
 723             SCM_SETCDR (tl2, scm_cons (SCM_CONSP (tmp)
 724                                        ? *copy
 725                                        : tmp,
 726                                        SCM_EOL));
 727           if (')' != (c = scm_flush_ws (port, name)))
 728             SCM_MISC_ERROR ("missing close paren", SCM_EOL);
 729           goto exit;
 730         }
 731
 732       new_tail = scm_cons (tmp, SCM_EOL);
 733       SCM_SETCDR (tl, new_tail);
 734       tl = new_tail;
 735
 736       if (SCM_COPY_SOURCE_P)
 737         {
 738           SCM new_tail2 = scm_cons (SCM_CONSP (tmp) ? *copy : tmp, SCM_EOL);
 739           SCM_SETCDR (tl2, new_tail2);
 740           tl2 = new_tail2;
 741         }
 742     }
 743 exit:
 744   scm_whash_insert (scm_source_whash,
 745                     ans,
 746                     scm_make_srcprops (line,
 747                                        column,
 748                                        SCM_FILENAME (port),
 749                                        SCM_COPY_SOURCE_P
 750                                        ? *copy = ans2
 751                                        : SCM_UNDEFINED,
 752                                        SCM_EOL));
 753   return ans;
 754 }
 755 #undef FUNC_NAME
 756
 757
 758 \f
 759
 760 /* Manipulate the read-hash-procedures alist.  This could be written in
 761    Scheme, but maybe it will also be used by C code during initialisation.  */
 762 SCM_DEFINE (scm_read_hash_extend, "read-hash-extend", 2, 0, 0,
 763             (SCM chr, SCM proc),
 764             "Install the procedure @var{proc} for reading expressions\n"
 765             "starting with the character sequence @code{#} and @var{chr}.\n"
 766             "@var{proc} will be called with two arguments:  the character\n"
 767             "@var{chr} and the port to read further data from. The object\n"
 768             "returned will be the return value of @code{read}.")
 769 #define FUNC_NAME s_scm_read_hash_extend
 770 {
 771   SCM this;
 772   SCM prev;
 773
 774   SCM_VALIDATE_CHAR (1, chr);
 775   SCM_ASSERT (SCM_FALSEP (proc)
 776               || SCM_EQ_P (scm_procedure_p (proc), SCM_BOOL_T),
 777               proc, SCM_ARG2, FUNC_NAME);
 778
 779   /* Check if chr is already in the alist.  */
 780   this = *scm_read_hash_procedures;
 781   prev = SCM_BOOL_F;
 782   while (1)
 783     {
 784       if (SCM_NULLP (this))
 785         {
 786           /* not found, so add it to the beginning.  */
 787           if (!SCM_FALSEP (proc))
 788             {
 789               *scm_read_hash_procedures =
 790                 scm_cons (scm_cons (chr, proc), *scm_read_hash_procedures);
 791             }
 792           break;
 793         }
 794       if (SCM_EQ_P (chr, SCM_CAAR (this)))
 795         {
 796           /* already in the alist.  */
 797           if (SCM_FALSEP (proc))
 798             {
 799               /* remove it.  */
 800               if (SCM_FALSEP (prev))
 801                 {
 802                   *scm_read_hash_procedures =
 803                     SCM_CDR (*scm_read_hash_procedures);
 804                 }
 805               else
 806                 scm_set_cdr_x (prev, SCM_CDR (this));
 807             }
 808           else
 809             {
 810               /* replace it.  */
 811               scm_set_cdr_x (SCM_CAR (this), proc);
 812             }
 813           break;
 814         }
 815       prev = this;
 816       this = SCM_CDR (this);
 817     }
 818
 819   return SCM_UNSPECIFIED;
 820 }
 821 #undef FUNC_NAME
 822
 823 /* Recover the read-hash procedure corresponding to char c.  */
 824 static SCM
 825 scm_get_hash_procedure (int c)
 826 {
 827   SCM rest = *scm_read_hash_procedures;
 828
 829   while (1)
 830     {
 831       if (SCM_NULLP (rest))
 832         return SCM_BOOL_F;
 833
 834       if (SCM_CHAR (SCM_CAAR (rest)) == c)
 835         return SCM_CDAR (rest);
 836
 837       rest = SCM_CDR (rest);
 838     }
 839 }
 840
 841 void
 842 scm_init_read ()
 843 {
 844   scm_read_hash_procedures =
 845     SCM_VARIABLE_LOC (scm_c_define ("read-hash-procedures", SCM_EOL));
 846
 847   scm_init_opts (scm_read_options, scm_read_opts, SCM_N_READ_OPTIONS);
 848 #ifndef SCM_MAGIC_SNARFER
 849 #include "libguile/read.x"
 850 #endif
 851 }
 852
 853 /*
 854   Local Variables:
 855   c-file-style: "gnu"
 856   End:
 857 */