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                         lex_class = PRINTABLE;
 190                         if (c <= 0x7f)
 191                                 lex_class = lex_classes[c];
 192                 }
 193         } while (lex_class & IGNORE);
 194         return c;
 195 }
 196
 197 static int
 198 lex_quoted(FILE *in)
 199 {
 200         int     c;
 201         int     v;
 202         int     count;
 203
 204         c = lex_get(in);
 205         if (c == EOF) {
 206         eof:
 207                 lex_class = ENDOFFILE;
 208                 return 0;
 209         }
 210         lex_class = 0;
 211         c &= 0x7f;
 212         switch (c) {
 213         case 'a':
 214                 return '\a';
 215         case 'b':
 216                 return '\b';
 217         case 't':
 218                 return '\t';
 219         case 'n':
 220                 return '\n';
 221         case 'r':
 222                 return '\r';
 223         case 'f':
 224                 return '\f';
 225         case 'v':
 226                 return '\v';
 227         case '0':
 228         case '1':
 229         case '2':
 230         case '3':
 231         case '4':
 232         case '5':
 233         case '6':
 234         case '7':
 235                 v = c - '0';
 236                 count = 1;
 237                 while (count <= 3) {
 238                         c = lex_get(in);
 239                         if (c == EOF)
 240                                 goto eof;
 241                         c &= 0x7f;
 242                         if (c < '0' || '7' < c) {
 243                                 lex_unget(c);
 244                                 break;
 245                         }
 246                         v = (v << 3) + c - '0';
 247                         ++count;
 248                 }
 249                 return v;
 250         default:
 251                 return c;
 252         }
 253 }
 254
 255 #ifndef AO_SCHEME_TOKEN_MAX
 256 #define AO_SCHEME_TOKEN_MAX     128
 257 #endif
 258
 259 static char     token_string[AO_SCHEME_TOKEN_MAX];
 260 static int32_t  token_int;
 261 static int      token_len;
 262
 263 static void start_token(void) {
 264         token_len = 0;
 265 }
 266
 267 static void add_token(int c) {
 268         if (c && token_len < AO_SCHEME_TOKEN_MAX - 1)
 269                 token_string[token_len++] = c;
 270 }
 271
 272 static void end_token(void) {
 273         token_string[token_len] = '\0';
 274 }
 275
 276 #ifdef AO_SCHEME_FEATURE_FLOAT
 277 static float    token_float;
 278
 279 struct namedfloat {
 280         const char      *name;
 281         float           value;
 282 };
 283
 284 static const struct namedfloat namedfloats[] = {
 285         { .name = "+inf.0", .value = INFINITY },
 286         { .name = "-inf.0", .value = -INFINITY },
 287         { .name = "+nan.0", .value = NAN },
 288         { .name = "-nan.0", .value = NAN },
 289 };
 290
 291 #define NUM_NAMED_FLOATS        (sizeof namedfloats / sizeof namedfloats[0])
 292 #endif
 293
 294 static int
 295 parse_int(FILE *in, int base)
 296 {
 297         int     cval;
 298         int     c;
 299
 300         token_int = 0;
 301         for (;;) {
 302                 c = lexc(in);
 303                 if ((lex_class & HEX_DIGIT) == 0) {
 304                         lex_unget(c);
 305                         return NUM;
 306                 }
 307                 if ('0' <= c && c <= '9')
 308                         cval = c - '0';
 309                 else
 310                         cval = (c | ('a' - 'A')) - 'a' + 10;
 311                 token_int = token_int * base + cval;
 312         }
 313         return NUM;
 314 }
 315
 316 static int
 317 _lex(FILE *in)
 318 {
 319         int     c;
 320
 321         start_token();
 322         for (;;) {
 323                 c = lexc(in);
 324                 if (lex_class & ENDOFFILE)
 325                         return END;
 326
 327                 if (lex_class & WHITE)
 328                         continue;
 329
 330                 if (lex_class & COMMENT) {
 331                         while ((c = lexc(in)) != '\n') {
 332                                 if (lex_class & ENDOFFILE)
 333                                         return END;
 334                         }
 335                         continue;
 336                 }
 337
 338                 if (lex_class & SPECIAL) {
 339                         switch (c) {
 340                         case '(':
 341                         case '[':
 342                                 return OPEN;
 343                         case ')':
 344                         case ']':
 345                                 return CLOSE;
 346                         case '\'':
 347                                 return QUOTE;
 348                         case '.':
 349                                 return DOT;
 350 #ifdef AO_SCHEME_FEATURE_QUASI
 351                         case '`':
 352                                 return QUASIQUOTE;
 353                         case ',':
 354                                 c = lexc(in);
 355                                 if (c == '@') {
 356                                         return UNQUOTE_SPLICING;
 357                                 } else {
 358                                         lex_unget(c);
 359                                         return UNQUOTE;
 360                                 }
 361 #endif
 362                         }
 363                 }
 364                 if (c == '#') {
 365                         c = lexc(in);
 366                         switch (c) {
 367                         case 't':
 368                                 return TRUE_TOKEN;
 369                         case 'f':
 370                                 return FALSE_TOKEN;
 371 #ifdef AO_SCHEME_FEATURE_VECTOR
 372                         case '(':
 373                                 return OPEN_VECTOR;
 374 #endif
 375                         case '\\':
 376                                 for (;;) {
 377                                         c = lexc(in);
 378                                         if (token_len == 0) {
 379                                                 add_token(c);
 380                                                 if (!(lex_class & ALPHA))
 381                                                         break;
 382                                         } else {
 383                                                 if (lex_class & ALPHA)
 384                                                         add_token(c);
 385                                                 else {
 386                                                         lex_unget(c);
 387                                                         break;
 388                                                 }
 389                                         }
 390                                 }
 391                                 end_token();
 392                                 if (token_len == 1)
 393                                         token_int = token_string[0];
 394                                 else if (!strcmp(token_string, "space"))
 395                                         token_int = ' ';
 396                                 else if (!strcmp(token_string, "newline"))
 397                                         token_int = '\n';
 398                                 else if (!strcmp(token_string, "tab"))
 399                                         token_int = '\t';
 400                                 else if (!strcmp(token_string, "return"))
 401                                         token_int = '\r';
 402                                 else if (!strcmp(token_string, "formfeed"))
 403                                         token_int = '\f';
 404                                 else {
 405                                         ao_scheme_error(AO_SCHEME_INVALID, "invalid character token #\\%s", token_string);
 406                                         continue;
 407                                 }
 408                                 return NUM;
 409                         case 'x':
 410                                 return parse_int(in, 16);
 411                         case 'o':
 412                                 return parse_int(in, 8);
 413                         case 'b':
 414                                 return parse_int(in, 2);
 415                         }
 416                 }
 417                 if (lex_class & STRINGC) {
 418                         for (;;) {
 419                                 c = lexc(in);
 420                                 if (c == '\\')
 421                                         c = lex_quoted(in);
 422                                 if (lex_class & (STRINGC|ENDOFFILE)) {
 423                                         end_token();
 424                                         return STRING;
 425                                 }
 426                                 add_token(c);
 427                         }
 428                 }
 429                 if (lex_class & PRINTABLE) {
 430 #ifdef AO_SCHEME_FEATURE_FLOAT
 431                         int     isfloat = 1;
 432                         int     epos = 0;
 433 #endif
 434                         int     hasdigit = 0;
 435                         int     isneg = 0;
 436                         int     isint = 1;
 437
 438                         token_int = 0;
 439                         for (;;) {
 440                                 if (!(lex_class & NUMBER)) {
 441                                         isint = 0;
 442 #ifdef AO_SCHEME_FEATURE_FLOAT
 443                                         isfloat = 0;
 444 #endif
 445                                 } else {
 446 #ifdef AO_SCHEME_FEATURE_FLOAT
 447                                         if (!(lex_class & INTEGER))
 448                                                 isint = 0;
 449                                         if (token_len != epos &&
 450                                             (lex_class & SIGN))
 451                                         {
 452                                                 isint = 0;
 453                                                 isfloat = 0;
 454                                         }
 455 #endif
 456                                         if (c == '-')
 457                                                 isneg = 1;
 458 #ifdef AO_SCHEME_FEATURE_FLOAT
 459                                         if (c == '.' && epos != 0)
 460                                                 isfloat = 0;
 461                                         if (c == 'e' || c == 'E') {
 462                                                 if (token_len == 0)
 463                                                         isfloat = 0;
 464                                                 else
 465                                                         epos = token_len + 1;
 466                                         }
 467 #endif
 468                                         if (lex_class & DIGIT) {
 469                                                 hasdigit = 1;
 470                                                 if (isint)
 471                                                         token_int = token_int * 10 + c - '0';
 472                                         }
 473                                 }
 474                                 add_token (c);
 475                                 c = lexc (in);
 476                                 if ((lex_class & (NOTNAME))
 477 #ifdef AO_SCHEME_FEATURE_FLOAT
 478                                     && (c != '.' || !isfloat)
 479 #endif
 480                                         ) {
 481 #ifdef AO_SCHEME_FEATURE_FLOAT
 482                                         unsigned int u;
 483 #endif
 484                                         lex_unget(c);
 485                                         end_token ();
 486                                         if (isint && hasdigit) {
 487                                                 if (isneg)
 488                                                         token_int = -token_int;
 489                                                 return NUM;
 490                                         }
 491 #ifdef AO_SCHEME_FEATURE_FLOAT
 492                                         if (isfloat && hasdigit) {
 493                                                 token_float = strtof(token_string, NULL);
 494                                                 return FLOAT;
 495                                         }
 496                                         for (u = 0; u < NUM_NAMED_FLOATS; u++)
 497                                                 if (!strcmp(namedfloats[u].name, token_string)) {
 498                                                         token_float = namedfloats[u].value;
 499                                                         return FLOAT;
 500                                                 }
 501 #endif
 502                                         return NAME;
 503                                 }
 504                         }
 505                 }
 506         }
 507 }
 508
 509 static inline int lex(FILE *in)
 510 {
 511         int     parse_token = _lex(in);
 512         RDBGI("token %d \"%s\"\n", parse_token, token_string);
 513         return parse_token;
 514 }
 515
 516 static int parse_token;
 517
 518 int                     ao_scheme_read_list;
 519 struct ao_scheme_cons   *ao_scheme_read_cons;
 520 struct ao_scheme_cons   *ao_scheme_read_cons_tail;
 521 struct ao_scheme_cons   *ao_scheme_read_stack;
 522 static int              ao_scheme_read_state;
 523
 524 #define READ_IN_QUOTE   0x01
 525 #define READ_SAW_DOT    0x02
 526 #define READ_DONE_DOT   0x04
 527 #define READ_SAW_VECTOR 0x08
 528
 529 static int
 530 push_read_stack(int read_state)
 531 {
 532         RDBGI("push read stack %p 0x%x\n", ao_scheme_read_cons, read_state);
 533         RDBG_IN();
 534         if (ao_scheme_read_list) {
 535                 ao_scheme_read_stack = ao_scheme_cons_cons(ao_scheme_cons_poly(ao_scheme_read_cons),
 536                                                        ao_scheme_cons(ao_scheme_int_poly(read_state),
 537                                                                      ao_scheme_cons_poly(ao_scheme_read_stack)));
 538                 if (!ao_scheme_read_stack)
 539                         return 0;
 540         } else
 541                 ao_scheme_read_state = read_state;
 542         ao_scheme_read_cons = NULL;
 543         ao_scheme_read_cons_tail = NULL;
 544         return 1;
 545 }
 546
 547 static int
 548 pop_read_stack(void)
 549 {
 550         int     read_state = 0;
 551         if (ao_scheme_read_list) {
 552                 ao_scheme_read_cons = ao_scheme_poly_cons(ao_scheme_read_stack->car);
 553                 ao_scheme_read_stack = ao_scheme_poly_cons(ao_scheme_read_stack->cdr);
 554                 read_state = ao_scheme_poly_int(ao_scheme_read_stack->car);
 555                 ao_scheme_read_stack = ao_scheme_poly_cons(ao_scheme_read_stack->cdr);
 556                 for (ao_scheme_read_cons_tail = ao_scheme_read_cons;
 557                      ao_scheme_read_cons_tail && ao_scheme_read_cons_tail->cdr;
 558                      ao_scheme_read_cons_tail = ao_scheme_poly_cons(ao_scheme_read_cons_tail->cdr))
 559                         ;
 560         } else {
 561                 read_state = ao_scheme_read_state;
 562                 ao_scheme_read_cons = NULL;
 563                 ao_scheme_read_cons_tail = NULL;
 564                 ao_scheme_read_stack = NULL;
 565                 ao_scheme_read_state = 0;
 566         }
 567         RDBG_OUT();
 568         RDBGI("pop read stack %p %d\n", ao_scheme_read_cons, read_state);
 569         return read_state;
 570 }
 571
 572 #ifdef AO_SCHEME_FEATURE_VECTOR
 573 #define is_open(t) ((t) == OPEN || (t) == OPEN_VECTOR)
 574 #else
 575 #define is_open(t) ((t) == OPEN)
 576 #endif
 577
 578 ao_poly
 579 ao_scheme_read(FILE *in)
 580 {
 581         struct ao_scheme_atom   *atom;
 582         struct ao_scheme_string *string;
 583         int                     read_state;
 584         ao_poly                 v = AO_SCHEME_NIL;
 585
 586         ao_scheme_read_list = 0;
 587         read_state = 0;
 588         ao_scheme_read_cons = ao_scheme_read_cons_tail = ao_scheme_read_stack = NULL;
 589         for (;;) {
 590                 parse_token = lex(in);
 591                 while (is_open(parse_token)) {
 592 #ifdef AO_SCHEME_FEATURE_VECTOR
 593                         if (parse_token == OPEN_VECTOR)
 594                                 read_state |= READ_SAW_VECTOR;
 595 #endif
 596                         if (!push_read_stack(read_state))
 597                                 return AO_SCHEME_NIL;
 598                         ao_scheme_read_list++;
 599                         read_state = 0;
 600                         parse_token = lex(in);
 601                 }
 602
 603                 switch (parse_token) {
 604                 case END:
 605                 default:
 606                         if (ao_scheme_read_list)
 607                                 ao_scheme_error(AO_SCHEME_EOF, "unexpected end of file");
 608                         return _ao_scheme_atom_eof;
 609                         break;
 610                 case NAME:
 611                         atom = ao_scheme_atom_intern(token_string);
 612                         if (atom)
 613                                 v = ao_scheme_atom_poly(atom);
 614                         else
 615                                 v = AO_SCHEME_NIL;
 616                         break;
 617                 case NUM:
 618                         v = ao_scheme_integer_poly(token_int);
 619                         break;
 620 #ifdef AO_SCHEME_FEATURE_FLOAT
 621                 case FLOAT:
 622                         v = ao_scheme_float_get(token_float);
 623                         break;
 624 #endif
 625                 case TRUE_TOKEN:
 626                         v = _ao_scheme_bool_true;
 627                         break;
 628                 case FALSE_TOKEN:
 629                         v = _ao_scheme_bool_false;
 630                         break;
 631                 case STRING:
 632                         string = ao_scheme_string_new(token_string);
 633                         if (string)
 634                                 v = ao_scheme_string_poly(string);
 635                         else
 636                                 v = AO_SCHEME_NIL;
 637                         break;
 638                 case QUOTE:
 639 #ifdef AO_SCHEME_FEATURE_QUASI
 640                 case QUASIQUOTE:
 641                 case UNQUOTE:
 642                 case UNQUOTE_SPLICING:
 643 #endif
 644                         if (!push_read_stack(read_state))
 645                                 return AO_SCHEME_NIL;
 646                         ao_scheme_read_list++;
 647                         read_state = READ_IN_QUOTE;
 648                         switch (parse_token) {
 649                         case QUOTE:
 650                                 v = _ao_scheme_atom_quote;
 651                                 break;
 652 #ifdef AO_SCHEME_FEATURE_QUASI
 653                         case QUASIQUOTE:
 654                                 v = _ao_scheme_atom_quasiquote;
 655                                 break;
 656                         case UNQUOTE:
 657                                 v = _ao_scheme_atom_unquote;
 658                                 break;
 659                         case UNQUOTE_SPLICING:
 660                                 v = _ao_scheme_atom_unquote2dsplicing;
 661                                 break;
 662 #endif
 663                         }
 664                         break;
 665                 case CLOSE:
 666                         if (!ao_scheme_read_list) {
 667                                 v = AO_SCHEME_NIL;
 668                                 break;
 669                         }
 670                         v = ao_scheme_cons_poly(ao_scheme_read_cons);
 671                         --ao_scheme_read_list;
 672                         read_state = pop_read_stack();
 673 #ifdef AO_SCHEME_FEATURE_VECTOR
 674                         if (read_state & READ_SAW_VECTOR) {
 675                                 v = ao_scheme_vector_poly(ao_scheme_list_to_vector(ao_scheme_poly_cons(v)));
 676                                 read_state &= ~READ_SAW_VECTOR;
 677                         }
 678 #endif
 679                         break;
 680                 case DOT:
 681                         if (!ao_scheme_read_list) {
 682                                 ao_scheme_error(AO_SCHEME_INVALID, ". outside of cons");
 683                                 return AO_SCHEME_NIL;
 684                         }
 685                         if (!ao_scheme_read_cons) {
 686                                 ao_scheme_error(AO_SCHEME_INVALID, ". first in cons");
 687                                 return AO_SCHEME_NIL;
 688                         }
 689                         read_state |= READ_SAW_DOT;
 690                         continue;
 691                 }
 692
 693                 /* loop over QUOTE ends */
 694                 for (;;) {
 695                         if (!ao_scheme_read_list)
 696                                 return v;
 697
 698                         if (read_state & READ_DONE_DOT) {
 699                                 ao_scheme_error(AO_SCHEME_INVALID, ". not last in cons");
 700                                 return AO_SCHEME_NIL;
 701                         }
 702
 703                         if (read_state & READ_SAW_DOT) {
 704                                 read_state |= READ_DONE_DOT;
 705                                 ao_scheme_read_cons_tail->cdr = v;
 706                         } else {
 707                                 struct ao_scheme_cons   *read = ao_scheme_cons_cons(v, AO_SCHEME_NIL);
 708                                 if (!read)
 709                                         return AO_SCHEME_NIL;
 710
 711                                 if (ao_scheme_read_cons_tail)
 712                                         ao_scheme_read_cons_tail->cdr = ao_scheme_cons_poly(read);
 713                                 else
 714                                         ao_scheme_read_cons = read;
 715                                 ao_scheme_read_cons_tail = read;
 716                         }
 717
 718                         if (!(read_state & READ_IN_QUOTE) || !ao_scheme_read_cons->cdr)
 719                                 break;
 720
 721                         v = ao_scheme_cons_poly(ao_scheme_read_cons);
 722                         --ao_scheme_read_list;
 723                         read_state = pop_read_stack();
 724                 }
 725         }
 726         return v;
 727 }