git.gag.com Git - fw/altos/blob - src/scheme/ao_scheme_read.c

   1 /*
   2  * Copyright © 2016 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program 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  * General Public License for more details.
  13  */
  14
  15 #include "ao_scheme.h"
  16 #include "ao_scheme_read.h"
  17 #include <math.h>
  18 #include <stdlib.h>
  19
  20 static const uint16_t   lex_classes[128] = {
  21         IGNORE,                         /* ^@ */
  22         IGNORE,                         /* ^A */
  23         IGNORE,                         /* ^B */
  24         IGNORE,                         /* ^C */
  25         IGNORE,                         /* ^D */
  26         IGNORE,                         /* ^E */
  27         IGNORE,                         /* ^F */
  28         IGNORE,                         /* ^G */
  29         IGNORE,                         /* ^H */
  30         WHITE,                          /* ^I */
  31         WHITE,                          /* ^J */
  32         WHITE,                          /* ^K */
  33         WHITE,                          /* ^L */
  34         WHITE,                          /* ^M */
  35         IGNORE,                         /* ^N */
  36         IGNORE,                         /* ^O */
  37         IGNORE,                         /* ^P */
  38         IGNORE,                         /* ^Q */
  39         IGNORE,                         /* ^R */
  40         IGNORE,                         /* ^S */
  41         IGNORE,                         /* ^T */
  42         IGNORE,                         /* ^U */
  43         IGNORE,                         /* ^V */
  44         IGNORE,                         /* ^W */
  45         IGNORE,                         /* ^X */
  46         IGNORE,                         /* ^Y */
  47         IGNORE,                         /* ^Z */
  48         IGNORE,                         /* ^[ */
  49         IGNORE,                         /* ^\ */
  50         IGNORE,                         /* ^] */
  51         IGNORE,                         /* ^^ */
  52         IGNORE,                         /* ^_ */
  53         PRINTABLE|WHITE,                /*    */
  54         PRINTABLE,                      /* ! */
  55         PRINTABLE|STRINGC,              /* " */
  56         PRINTABLE,                      /* # */
  57         PRINTABLE,                      /* $ */
  58         PRINTABLE,                      /* % */
  59         PRINTABLE,                      /* & */
  60         PRINTABLE|SPECIAL,              /* ' */
  61         PRINTABLE|SPECIAL,              /* ( */
  62         PRINTABLE|SPECIAL,              /* ) */
  63         PRINTABLE,                      /* * */
  64         PRINTABLE|SIGN,                 /* + */
  65         PRINTABLE|SPECIAL_QUASI,        /* , */
  66         PRINTABLE|SIGN,                 /* - */
  67         PRINTABLE|SPECIAL|FLOATC,       /* . */
  68         PRINTABLE,                      /* / */
  69         PRINTABLE|DIGIT,                /* 0 */
  70         PRINTABLE|DIGIT,                /* 1 */
  71         PRINTABLE|DIGIT,                /* 2 */
  72         PRINTABLE|DIGIT,                /* 3 */
  73         PRINTABLE|DIGIT,                /* 4 */
  74         PRINTABLE|DIGIT,                /* 5 */
  75         PRINTABLE|DIGIT,                /* 6 */
  76         PRINTABLE|DIGIT,                /* 7 */
  77         PRINTABLE|DIGIT,                /* 8 */
  78         PRINTABLE|DIGIT,                /* 9 */
  79         PRINTABLE,                      /* : */
  80         PRINTABLE|COMMENT,              /* ; */
  81         PRINTABLE,                      /* < */
  82         PRINTABLE,                      /* = */
  83         PRINTABLE,                      /* > */
  84         PRINTABLE,                      /* ? */
  85         PRINTABLE,                      /*  @ */
  86         PRINTABLE|ALPHA|HEX_LETTER,     /*  A */
  87         PRINTABLE|ALPHA|HEX_LETTER,     /*  B */
  88         PRINTABLE|ALPHA|HEX_LETTER,     /*  C */
  89         PRINTABLE|ALPHA|HEX_LETTER,     /*  D */
  90         PRINTABLE|ALPHA|FLOATC|HEX_LETTER,/*  E */
  91         PRINTABLE|ALPHA|HEX_LETTER,     /*  F */
  92         PRINTABLE|ALPHA,                /*  G */
  93         PRINTABLE|ALPHA,                /*  H */
  94         PRINTABLE|ALPHA,                /*  I */
  95         PRINTABLE|ALPHA,                /*  J */
  96         PRINTABLE|ALPHA,                /*  K */
  97         PRINTABLE|ALPHA,                /*  L */
  98         PRINTABLE|ALPHA,                /*  M */
  99         PRINTABLE|ALPHA,                /*  N */
 100         PRINTABLE|ALPHA,                /*  O */
 101         PRINTABLE|ALPHA,                /*  P */
 102         PRINTABLE|ALPHA,                /*  Q */
 103         PRINTABLE|ALPHA,                /*  R */
 104         PRINTABLE|ALPHA,                /*  S */
 105         PRINTABLE|ALPHA,                /*  T */
 106         PRINTABLE|ALPHA,                /*  U */
 107         PRINTABLE|ALPHA,                /*  V */
 108         PRINTABLE|ALPHA,                /*  W */
 109         PRINTABLE|ALPHA,                /*  X */
 110         PRINTABLE|ALPHA,                /*  Y */
 111         PRINTABLE|ALPHA,                /*  Z */
 112         PRINTABLE,                      /*  [ */
 113         PRINTABLE,                      /*  \ */
 114         PRINTABLE,                      /*  ] */
 115         PRINTABLE,                      /*  ^ */
 116         PRINTABLE,                      /*  _ */
 117         PRINTABLE|SPECIAL_QUASI,        /*  ` */
 118         PRINTABLE|ALPHA|HEX_LETTER,     /*  a */
 119         PRINTABLE|ALPHA|HEX_LETTER,     /*  b */
 120         PRINTABLE|ALPHA|HEX_LETTER,     /*  c */
 121         PRINTABLE|ALPHA|HEX_LETTER,     /*  d */
 122         PRINTABLE|ALPHA|FLOATC|HEX_LETTER,/*  e */
 123         PRINTABLE|ALPHA|HEX_LETTER,     /*  f */
 124         PRINTABLE|ALPHA,                /*  g */
 125         PRINTABLE|ALPHA,                /*  h */
 126         PRINTABLE|ALPHA,                /*  i */
 127         PRINTABLE|ALPHA,                /*  j */
 128         PRINTABLE|ALPHA,                /*  k */
 129         PRINTABLE|ALPHA,                /*  l */
 130         PRINTABLE|ALPHA,                /*  m */
 131         PRINTABLE|ALPHA,                /*  n */
 132         PRINTABLE|ALPHA,                /*  o */
 133         PRINTABLE|ALPHA,                /*  p */
 134         PRINTABLE|ALPHA,                /*  q */
 135         PRINTABLE|ALPHA,                /*  r */
 136         PRINTABLE|ALPHA,                /*  s */
 137         PRINTABLE|ALPHA,                /*  t */
 138         PRINTABLE|ALPHA,                /*  u */
 139         PRINTABLE|ALPHA,                /*  v */
 140         PRINTABLE|ALPHA,                /*  w */
 141         PRINTABLE|ALPHA,                /*  x */
 142         PRINTABLE|ALPHA,                /*  y */
 143         PRINTABLE|ALPHA,                /*  z */
 144         PRINTABLE,                      /*  { */
 145         PRINTABLE,                      /*  | */
 146         PRINTABLE,                      /*  } */
 147         PRINTABLE,                      /*  ~ */
 148         IGNORE,                         /*  ^? */
 149 };
 150
 151 static int lex_unget_c;
 152
 153 #ifndef ao_scheme_getc
 154 #define ao_scheme_getc(f) getc(f)
 155 #endif
 156
 157 static inline int
 158 lex_get(FILE *in)
 159 {
 160         int     c;
 161         if (lex_unget_c) {
 162                 c = lex_unget_c;
 163                 lex_unget_c = 0;
 164         } else {
 165                 c = ao_scheme_getc(in);
 166         }
 167         return c;
 168 }
 169
 170 static inline void
 171 lex_unget(int c)
 172 {
 173         if (c != EOF)
 174                 lex_unget_c = c;
 175 }
 176
 177 static uint16_t lex_class;
 178
 179 static int
 180 lexc(FILE *in)
 181 {
 182         int     c;
 183         do {
 184                 c = lex_get(in);
 185                 if (c == EOF) {
 186                         c = 0;
 187                         lex_class = ENDOFFILE;
 188                 } else {
 189                         c &= 0x7f;
 190                         lex_class = lex_classes[c];
 191                 }
 192         } while (lex_class & IGNORE);
 193         return c;
 194 }
 195
 196 static int
 197 lex_quoted(FILE *in)
 198 {
 199         int     c;
 200         int     v;
 201         int     count;
 202
 203         c = lex_get(in);
 204         if (c == EOF) {
 205         eof:
 206                 lex_class = ENDOFFILE;
 207                 return 0;
 208         }
 209         lex_class = 0;
 210         c &= 0x7f;
 211         switch (c) {
 212         case 'a':
 213                 return '\a';
 214         case 'b':
 215                 return '\b';
 216         case 't':
 217                 return '\t';
 218         case 'n':
 219                 return '\n';
 220         case 'r':
 221                 return '\r';
 222         case 'f':
 223                 return '\f';
 224         case 'v':
 225                 return '\v';
 226         case '0':
 227         case '1':
 228         case '2':
 229         case '3':
 230         case '4':
 231         case '5':
 232         case '6':
 233         case '7':
 234                 v = c - '0';
 235                 count = 1;
 236                 while (count <= 3) {
 237                         c = lex_get(in);
 238                         if (c == EOF)
 239                                 goto eof;
 240                         c &= 0x7f;
 241                         if (c < '0' || '7' < c) {
 242                                 lex_unget(c);
 243                                 break;
 244                         }
 245                         v = (v << 3) + c - '0';
 246                         ++count;
 247                 }
 248                 return v;
 249         default:
 250                 return c;
 251         }
 252 }
 253
 254 #ifndef AO_SCHEME_TOKEN_MAX
 255 #define AO_SCHEME_TOKEN_MAX     128
 256 #endif
 257
 258 static char     token_string[AO_SCHEME_TOKEN_MAX];
 259 static int32_t  token_int;
 260 static int      token_len;
 261
 262 static void start_token(void) {
 263         token_len = 0;
 264 }
 265
 266 static void add_token(int c) {
 267         if (c && token_len < AO_SCHEME_TOKEN_MAX - 1)
 268                 token_string[token_len++] = c;
 269 }
 270
 271 static void end_token(void) {
 272         token_string[token_len] = '\0';
 273 }
 274
 275 #ifdef AO_SCHEME_FEATURE_FLOAT
 276 static float    token_float;
 277
 278 struct namedfloat {
 279         const char      *name;
 280         float           value;
 281 };
 282
 283 static const struct namedfloat namedfloats[] = {
 284         { .name = "+inf.0", .value = INFINITY },
 285         { .name = "-inf.0", .value = -INFINITY },
 286         { .name = "+nan.0", .value = NAN },
 287         { .name = "-nan.0", .value = NAN },
 288 };
 289
 290 #define NUM_NAMED_FLOATS        (sizeof namedfloats / sizeof namedfloats[0])
 291 #endif
 292
 293 static int
 294 parse_int(FILE *in, int base)
 295 {
 296         int     cval;
 297         int     c;
 298
 299         token_int = 0;
 300         for (;;) {
 301                 c = lexc(in);
 302                 if ((lex_class & HEX_DIGIT) == 0) {
 303                         lex_unget(c);
 304                         return NUM;
 305                 }
 306                 if ('0' <= c && c <= '9')
 307                         cval = c - '0';
 308                 else
 309                         cval = (c | ('a' - 'A')) - 'a' + 10;
 310                 token_int = token_int * base + cval;
 311         }
 312         return NUM;
 313 }
 314
 315 static int
 316 _lex(FILE *in)
 317 {
 318         int     c;
 319
 320         start_token();
 321         for (;;) {
 322                 c = lexc(in);
 323                 if (lex_class & ENDOFFILE)
 324                         return END;
 325
 326                 if (lex_class & WHITE)
 327                         continue;
 328
 329                 if (lex_class & COMMENT) {
 330                         while ((c = lexc(in)) != '\n') {
 331                                 if (lex_class & ENDOFFILE)
 332                                         return END;
 333                         }
 334                         continue;
 335                 }
 336
 337                 if (lex_class & SPECIAL) {
 338                         switch (c) {
 339                         case '(':
 340                         case '[':
 341                                 return OPEN;
 342                         case ')':
 343                         case ']':
 344                                 return CLOSE;
 345                         case '\'':
 346                                 return QUOTE;
 347                         case '.':
 348                                 return DOT;
 349 #ifdef AO_SCHEME_FEATURE_QUASI
 350                         case '`':
 351                                 return QUASIQUOTE;
 352                         case ',':
 353                                 c = lexc(in);
 354                                 if (c == '@') {
 355                                         return UNQUOTE_SPLICING;
 356                                 } else {
 357                                         lex_unget(c);
 358                                         return UNQUOTE;
 359                                 }
 360 #endif
 361                         }
 362                 }
 363                 if (c == '#') {
 364                         c = lexc(in);
 365                         switch (c) {
 366                         case 't':
 367                                 return TRUE_TOKEN;
 368                         case 'f':
 369                                 return FALSE_TOKEN;
 370 #ifdef AO_SCHEME_FEATURE_VECTOR
 371                         case '(':
 372                                 return OPEN_VECTOR;
 373 #endif
 374                         case '\\':
 375                                 for (;;) {
 376                                         c = lexc(in);
 377                                         if (token_len == 0) {
 378                                                 add_token(c);
 379                                                 if (!(lex_class & ALPHA))
 380                                                         break;
 381                                         } else {
 382                                                 if (lex_class & ALPHA)
 383                                                         add_token(c);
 384                                                 else {
 385                                                         lex_unget(c);
 386                                                         break;
 387                                                 }
 388                                         }
 389                                 }
 390                                 end_token();
 391                                 if (token_len == 1)
 392                                         token_int = token_string[0];
 393                                 else if (!strcmp(token_string, "space"))
 394                                         token_int = ' ';
 395                                 else if (!strcmp(token_string, "newline"))
 396                                         token_int = '\n';
 397                                 else if (!strcmp(token_string, "tab"))
 398                                         token_int = '\t';
 399                                 else if (!strcmp(token_string, "return"))
 400                                         token_int = '\r';
 401                                 else if (!strcmp(token_string, "formfeed"))
 402                                         token_int = '\f';
 403                                 else {
 404                                         ao_scheme_error(AO_SCHEME_INVALID, "invalid character token #\\%s", token_string);
 405                                         continue;
 406                                 }
 407                                 return NUM;
 408                         case 'x':
 409                                 return parse_int(in, 16);
 410                         case 'o':
 411                                 return parse_int(in, 8);
 412                         case 'b':
 413                                 return parse_int(in, 2);
 414                         }
 415                 }
 416                 if (lex_class & STRINGC) {
 417                         for (;;) {
 418                                 c = lexc(in);
 419                                 if (c == '\\')
 420                                         c = lex_quoted(in);
 421                                 if (lex_class & (STRINGC|ENDOFFILE)) {
 422                                         end_token();
 423                                         return STRING;
 424                                 }
 425                                 add_token(c);
 426                         }
 427                 }
 428                 if (lex_class & PRINTABLE) {
 429 #ifdef AO_SCHEME_FEATURE_FLOAT
 430                         int     isfloat = 1;
 431                         int     epos = 0;
 432 #endif
 433                         int     hasdigit = 0;
 434                         int     isneg = 0;
 435                         int     isint = 1;
 436
 437                         token_int = 0;
 438                         for (;;) {
 439                                 if (!(lex_class & NUMBER)) {
 440                                         isint = 0;
 441 #ifdef AO_SCHEME_FEATURE_FLOAT
 442                                         isfloat = 0;
 443 #endif
 444                                 } else {
 445 #ifdef AO_SCHEME_FEATURE_FLOAT
 446                                         if (!(lex_class & INTEGER))
 447                                                 isint = 0;
 448                                         if (token_len != epos &&
 449                                             (lex_class & SIGN))
 450                                         {
 451                                                 isint = 0;
 452                                                 isfloat = 0;
 453                                         }
 454 #endif
 455                                         if (c == '-')
 456                                                 isneg = 1;
 457 #ifdef AO_SCHEME_FEATURE_FLOAT
 458                                         if (c == '.' && epos != 0)
 459                                                 isfloat = 0;
 460                                         if (c == 'e' || c == 'E') {
 461                                                 if (token_len == 0)
 462                                                         isfloat = 0;
 463                                                 else
 464                                                         epos = token_len + 1;
 465                                         }
 466 #endif
 467                                         if (lex_class & DIGIT) {
 468                                                 hasdigit = 1;
 469                                                 if (isint)
 470                                                         token_int = token_int * 10 + c - '0';
 471                                         }
 472                                 }
 473                                 add_token (c);
 474                                 c = lexc (in);
 475                                 if ((lex_class & (NOTNAME))
 476 #ifdef AO_SCHEME_FEATURE_FLOAT
 477                                     && (c != '.' || !isfloat)
 478 #endif
 479                                         ) {
 480 #ifdef AO_SCHEME_FEATURE_FLOAT
 481                                         unsigned int u;
 482 #endif
 483                                         lex_unget(c);
 484                                         end_token ();
 485                                         if (isint && hasdigit) {
 486                                                 if (isneg)
 487                                                         token_int = -token_int;
 488                                                 return NUM;
 489                                         }
 490 #ifdef AO_SCHEME_FEATURE_FLOAT
 491                                         if (isfloat && hasdigit) {
 492                                                 token_float = strtof(token_string, NULL);
 493                                                 return FLOAT;
 494                                         }
 495                                         for (u = 0; u < NUM_NAMED_FLOATS; u++)
 496                                                 if (!strcmp(namedfloats[u].name, token_string)) {
 497                                                         token_float = namedfloats[u].value;
 498                                                         return FLOAT;
 499                                                 }
 500 #endif
 501                                         return NAME;
 502                                 }
 503                         }
 504                 }
 505         }
 506 }
 507
 508 static inline int lex(FILE *in)
 509 {
 510         int     parse_token = _lex(in);
 511         RDBGI("token %d \"%s\"\n", parse_token, token_string);
 512         return parse_token;
 513 }
 514
 515 static int parse_token;
 516
 517 int                     ao_scheme_read_list;
 518 struct ao_scheme_cons   *ao_scheme_read_cons;
 519 struct ao_scheme_cons   *ao_scheme_read_cons_tail;
 520 struct ao_scheme_cons   *ao_scheme_read_stack;
 521 static int              ao_scheme_read_state;
 522
 523 #define READ_IN_QUOTE   0x01
 524 #define READ_SAW_DOT    0x02
 525 #define READ_DONE_DOT   0x04
 526 #define READ_SAW_VECTOR 0x08
 527
 528 static int
 529 push_read_stack(int read_state)
 530 {
 531         RDBGI("push read stack %p 0x%x\n", ao_scheme_read_cons, read_state);
 532         RDBG_IN();
 533         if (ao_scheme_read_list) {
 534                 ao_scheme_read_stack = ao_scheme_cons_cons(ao_scheme_cons_poly(ao_scheme_read_cons),
 535                                                        ao_scheme_cons(ao_scheme_int_poly(read_state),
 536                                                                      ao_scheme_cons_poly(ao_scheme_read_stack)));
 537                 if (!ao_scheme_read_stack)
 538                         return 0;
 539         } else
 540                 ao_scheme_read_state = read_state;
 541         ao_scheme_read_cons = NULL;
 542         ao_scheme_read_cons_tail = NULL;
 543         return 1;
 544 }
 545
 546 static int
 547 pop_read_stack(void)
 548 {
 549         int     read_state = 0;
 550         if (ao_scheme_read_list) {
 551                 ao_scheme_read_cons = ao_scheme_poly_cons(ao_scheme_read_stack->car);
 552                 ao_scheme_read_stack = ao_scheme_poly_cons(ao_scheme_read_stack->cdr);
 553                 read_state = ao_scheme_poly_int(ao_scheme_read_stack->car);
 554                 ao_scheme_read_stack = ao_scheme_poly_cons(ao_scheme_read_stack->cdr);
 555                 for (ao_scheme_read_cons_tail = ao_scheme_read_cons;
 556                      ao_scheme_read_cons_tail && ao_scheme_read_cons_tail->cdr;
 557                      ao_scheme_read_cons_tail = ao_scheme_poly_cons(ao_scheme_read_cons_tail->cdr))
 558                         ;
 559         } else {
 560                 read_state = ao_scheme_read_state;
 561                 ao_scheme_read_cons = NULL;
 562                 ao_scheme_read_cons_tail = NULL;
 563                 ao_scheme_read_stack = NULL;
 564                 ao_scheme_read_state = 0;
 565         }
 566         RDBG_OUT();
 567         RDBGI("pop read stack %p %d\n", ao_scheme_read_cons, read_state);
 568         return read_state;
 569 }
 570
 571 #ifdef AO_SCHEME_FEATURE_VECTOR
 572 #define is_open(t) ((t) == OPEN || (t) == OPEN_VECTOR)
 573 #else
 574 #define is_open(t) ((t) == OPEN)
 575 #endif
 576
 577 ao_poly
 578 ao_scheme_read(FILE *in)
 579 {
 580         struct ao_scheme_atom   *atom;
 581         struct ao_scheme_string *string;
 582         int                     read_state;
 583         ao_poly                 v = AO_SCHEME_NIL;
 584
 585         ao_scheme_read_list = 0;
 586         read_state = 0;
 587         ao_scheme_read_cons = ao_scheme_read_cons_tail = ao_scheme_read_stack = NULL;
 588         for (;;) {
 589                 parse_token = lex(in);
 590                 while (is_open(parse_token)) {
 591 #ifdef AO_SCHEME_FEATURE_VECTOR
 592                         if (parse_token == OPEN_VECTOR)
 593                                 read_state |= READ_SAW_VECTOR;
 594 #endif
 595                         if (!push_read_stack(read_state))
 596                                 return AO_SCHEME_NIL;
 597                         ao_scheme_read_list++;
 598                         read_state = 0;
 599                         parse_token = lex(in);
 600                 }
 601
 602                 switch (parse_token) {
 603                 case END:
 604                 default:
 605                         if (ao_scheme_read_list)
 606                                 ao_scheme_error(AO_SCHEME_EOF, "unexpected end of file");
 607                         return _ao_scheme_atom_eof;
 608                         break;
 609                 case NAME:
 610                         atom = ao_scheme_atom_intern(token_string);
 611                         if (atom)
 612                                 v = ao_scheme_atom_poly(atom);
 613                         else
 614                                 v = AO_SCHEME_NIL;
 615                         break;
 616                 case NUM:
 617                         v = ao_scheme_integer_poly(token_int);
 618                         break;
 619 #ifdef AO_SCHEME_FEATURE_FLOAT
 620                 case FLOAT:
 621                         v = ao_scheme_float_get(token_float);
 622                         break;
 623 #endif
 624                 case TRUE_TOKEN:
 625                         v = _ao_scheme_bool_true;
 626                         break;
 627                 case FALSE_TOKEN:
 628                         v = _ao_scheme_bool_false;
 629                         break;
 630                 case STRING:
 631                         string = ao_scheme_string_new(token_string);
 632                         if (string)
 633                                 v = ao_scheme_string_poly(string);
 634                         else
 635                                 v = AO_SCHEME_NIL;
 636                         break;
 637                 case QUOTE:
 638 #ifdef AO_SCHEME_FEATURE_QUASI
 639                 case QUASIQUOTE:
 640                 case UNQUOTE:
 641                 case UNQUOTE_SPLICING:
 642 #endif
 643                         if (!push_read_stack(read_state))
 644                                 return AO_SCHEME_NIL;
 645                         ao_scheme_read_list++;
 646                         read_state = READ_IN_QUOTE;
 647                         switch (parse_token) {
 648                         case QUOTE:
 649                                 v = _ao_scheme_atom_quote;
 650                                 break;
 651 #ifdef AO_SCHEME_FEATURE_QUASI
 652                         case QUASIQUOTE:
 653                                 v = _ao_scheme_atom_quasiquote;
 654                                 break;
 655                         case UNQUOTE:
 656                                 v = _ao_scheme_atom_unquote;
 657                                 break;
 658                         case UNQUOTE_SPLICING:
 659                                 v = _ao_scheme_atom_unquote2dsplicing;
 660                                 break;
 661 #endif
 662                         }
 663                         break;
 664                 case CLOSE:
 665                         if (!ao_scheme_read_list) {
 666                                 v = AO_SCHEME_NIL;
 667                                 break;
 668                         }
 669                         v = ao_scheme_cons_poly(ao_scheme_read_cons);
 670                         --ao_scheme_read_list;
 671                         read_state = pop_read_stack();
 672 #ifdef AO_SCHEME_FEATURE_VECTOR
 673                         if (read_state & READ_SAW_VECTOR) {
 674                                 v = ao_scheme_vector_poly(ao_scheme_list_to_vector(ao_scheme_poly_cons(v)));
 675                                 read_state &= ~READ_SAW_VECTOR;
 676                         }
 677 #endif
 678                         break;
 679                 case DOT:
 680                         if (!ao_scheme_read_list) {
 681                                 ao_scheme_error(AO_SCHEME_INVALID, ". outside of cons");
 682                                 return AO_SCHEME_NIL;
 683                         }
 684                         if (!ao_scheme_read_cons) {
 685                                 ao_scheme_error(AO_SCHEME_INVALID, ". first in cons");
 686                                 return AO_SCHEME_NIL;
 687                         }
 688                         read_state |= READ_SAW_DOT;
 689                         continue;
 690                 }
 691
 692                 /* loop over QUOTE ends */
 693                 for (;;) {
 694                         if (!ao_scheme_read_list)
 695                                 return v;
 696
 697                         if (read_state & READ_DONE_DOT) {
 698                                 ao_scheme_error(AO_SCHEME_INVALID, ". not last in cons");
 699                                 return AO_SCHEME_NIL;
 700                         }
 701
 702                         if (read_state & READ_SAW_DOT) {
 703                                 read_state |= READ_DONE_DOT;
 704                                 ao_scheme_read_cons_tail->cdr = v;
 705                         } else {
 706                                 struct ao_scheme_cons   *read = ao_scheme_cons_cons(v, AO_SCHEME_NIL);
 707                                 if (!read)
 708                                         return AO_SCHEME_NIL;
 709
 710                                 if (ao_scheme_read_cons_tail)
 711                                         ao_scheme_read_cons_tail->cdr = ao_scheme_cons_poly(read);
 712                                 else
 713                                         ao_scheme_read_cons = read;
 714                                 ao_scheme_read_cons_tail = read;
 715                         }
 716
 717                         if (!(read_state & READ_IN_QUOTE) || !ao_scheme_read_cons->cdr)
 718                                 break;
 719
 720                         v = ao_scheme_cons_poly(ao_scheme_read_cons);
 721                         --ao_scheme_read_list;
 722                         read_state = pop_read_stack();
 723                 }
 724         }
 725         return v;
 726 }