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   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_lisp.h"
  16 #include "ao_lisp_read.h"
  17
  18 static const uint16_t   lex_classes[128] = {
  19         IGNORE,         /* ^@ */
  20         IGNORE,         /* ^A */
  21         IGNORE,         /* ^B */
  22         IGNORE,         /* ^C */
  23         IGNORE,         /* ^D */
  24         IGNORE,         /* ^E */
  25         IGNORE,         /* ^F */
  26         IGNORE,         /* ^G */
  27         IGNORE,         /* ^H */
  28         WHITE,          /* ^I */
  29         WHITE,          /* ^J */
  30         WHITE,          /* ^K */
  31         WHITE,          /* ^L */
  32         WHITE,          /* ^M */
  33         IGNORE,         /* ^N */
  34         IGNORE,         /* ^O */
  35         IGNORE,         /* ^P */
  36         IGNORE,         /* ^Q */
  37         IGNORE,         /* ^R */
  38         IGNORE,         /* ^S */
  39         IGNORE,         /* ^T */
  40         IGNORE,         /* ^U */
  41         IGNORE,         /* ^V */
  42         IGNORE,         /* ^W */
  43         IGNORE,         /* ^X */
  44         IGNORE,         /* ^Y */
  45         IGNORE,         /* ^Z */
  46         IGNORE,         /* ^[ */
  47         IGNORE,         /* ^\ */
  48         IGNORE,         /* ^] */
  49         IGNORE,         /* ^^ */
  50         IGNORE,         /* ^_ */
  51         PRINTABLE|WHITE,        /*    */
  52         PRINTABLE,              /* ! */
  53         PRINTABLE|STRINGC,      /* " */
  54         PRINTABLE|COMMENT,      /* # */
  55         PRINTABLE,              /* $ */
  56         PRINTABLE,              /* % */
  57         PRINTABLE,              /* & */
  58         PRINTABLE|QUOTEC,       /* ' */
  59         PRINTABLE|BRA,          /* ( */
  60         PRINTABLE|KET,          /* ) */
  61         PRINTABLE,              /* * */
  62         PRINTABLE|SIGN,         /* + */
  63         PRINTABLE,              /* , */
  64         PRINTABLE|SIGN,         /* - */
  65         PRINTABLE|DOTC,         /* . */
  66         PRINTABLE,              /* / */
  67         PRINTABLE|DIGIT,        /* 0 */
  68         PRINTABLE|DIGIT,        /* 1 */
  69         PRINTABLE|DIGIT,        /* 2 */
  70         PRINTABLE|DIGIT,        /* 3 */
  71         PRINTABLE|DIGIT,        /* 4 */
  72         PRINTABLE|DIGIT,        /* 5 */
  73         PRINTABLE|DIGIT,        /* 6 */
  74         PRINTABLE|DIGIT,        /* 7 */
  75         PRINTABLE|DIGIT,        /* 8 */
  76         PRINTABLE|DIGIT,        /* 9 */
  77         PRINTABLE,              /* : */
  78         PRINTABLE|COMMENT,      /* ; */
  79         PRINTABLE,              /* < */
  80         PRINTABLE,              /* = */
  81         PRINTABLE,              /* > */
  82         PRINTABLE,              /* ? */
  83         PRINTABLE,              /*  @ */
  84         PRINTABLE,              /*  A */
  85         PRINTABLE,              /*  B */
  86         PRINTABLE,              /*  C */
  87         PRINTABLE,              /*  D */
  88         PRINTABLE,              /*  E */
  89         PRINTABLE,              /*  F */
  90         PRINTABLE,              /*  G */
  91         PRINTABLE,              /*  H */
  92         PRINTABLE,              /*  I */
  93         PRINTABLE,              /*  J */
  94         PRINTABLE,              /*  K */
  95         PRINTABLE,              /*  L */
  96         PRINTABLE,              /*  M */
  97         PRINTABLE,              /*  N */
  98         PRINTABLE,              /*  O */
  99         PRINTABLE,              /*  P */
 100         PRINTABLE,              /*  Q */
 101         PRINTABLE,              /*  R */
 102         PRINTABLE,              /*  S */
 103         PRINTABLE,              /*  T */
 104         PRINTABLE,              /*  U */
 105         PRINTABLE,              /*  V */
 106         PRINTABLE,              /*  W */
 107         PRINTABLE,              /*  X */
 108         PRINTABLE,              /*  Y */
 109         PRINTABLE,              /*  Z */
 110         PRINTABLE,              /*  [ */
 111         PRINTABLE|BACKSLASH,    /*  \ */
 112         PRINTABLE,              /*  ] */
 113         PRINTABLE,              /*  ^ */
 114         PRINTABLE,              /*  _ */
 115         PRINTABLE,              /*  ` */
 116         PRINTABLE,              /*  a */
 117         PRINTABLE,              /*  b */
 118         PRINTABLE,              /*  c */
 119         PRINTABLE,              /*  d */
 120         PRINTABLE,              /*  e */
 121         PRINTABLE,              /*  f */
 122         PRINTABLE,              /*  g */
 123         PRINTABLE,              /*  h */
 124         PRINTABLE,              /*  i */
 125         PRINTABLE,              /*  j */
 126         PRINTABLE,              /*  k */
 127         PRINTABLE,              /*  l */
 128         PRINTABLE,              /*  m */
 129         PRINTABLE,              /*  n */
 130         PRINTABLE,              /*  o */
 131         PRINTABLE,              /*  p */
 132         PRINTABLE,              /*  q */
 133         PRINTABLE,              /*  r */
 134         PRINTABLE,              /*  s */
 135         PRINTABLE,              /*  t */
 136         PRINTABLE,              /*  u */
 137         PRINTABLE,              /*  v */
 138         PRINTABLE,              /*  w */
 139         PRINTABLE,              /*  x */
 140         PRINTABLE,              /*  y */
 141         PRINTABLE,              /*  z */
 142         PRINTABLE,              /*  { */
 143         PRINTABLE|VBAR,         /*  | */
 144         PRINTABLE,              /*  } */
 145         PRINTABLE|TWIDDLE,      /*  ~ */
 146         IGNORE,                 /*  ^? */
 147 };
 148
 149 static int lex_unget_c;
 150
 151 static inline int
 152 lex_get()
 153 {
 154         int     c;
 155         if (lex_unget_c) {
 156                 c = lex_unget_c;
 157                 lex_unget_c = 0;
 158         } else {
 159                 c = ao_lisp_getc();
 160         }
 161         return c;
 162 }
 163
 164 static inline void
 165 lex_unget(int c)
 166 {
 167         if (c != EOF)
 168                 lex_unget_c = c;
 169 }
 170
 171 static int
 172 lex_quoted (void)
 173 {
 174         int     c;
 175         int     v;
 176         int     count;
 177
 178         c = lex_get();
 179         if (c == EOF)
 180                 return EOF;
 181         c &= 0x7f;
 182         switch (c) {
 183         case 'n':
 184                 return '\n';
 185         case 'f':
 186                 return '\f';
 187         case 'b':
 188                 return '\b';
 189         case 'r':
 190                 return '\r';
 191         case 'v':
 192                 return '\v';
 193         case 't':
 194                 return '\t';
 195         case '0':
 196         case '1':
 197         case '2':
 198         case '3':
 199         case '4':
 200         case '5':
 201         case '6':
 202         case '7':
 203                 v = c - '0';
 204                 count = 1;
 205                 while (count <= 3) {
 206                         c = lex_get();
 207                         if (c == EOF)
 208                                 return EOF;
 209                         c &= 0x7f;
 210                         if (c < '0' || '7' < c) {
 211                                 lex_unget(c);
 212                                 break;
 213                         }
 214                         v = (v << 3) + c - '0';
 215                         ++count;
 216                 }
 217                 return v;
 218         default:
 219                 return c;
 220         }
 221 }
 222
 223 static uint16_t lex_class;
 224
 225 static int
 226 lexc(void)
 227 {
 228         int     c;
 229         do {
 230                 c = lex_get();
 231                 if (c == EOF) {
 232                         lex_class = ENDOFFILE;
 233                         c = 0;
 234                 } else {
 235                         c &= 0x7f;
 236                         lex_class = lex_classes[c];
 237                         if (lex_class & BACKSLASH) {
 238                                 c = lex_quoted();
 239                                 if (c == EOF)
 240                                         lex_class = ENDOFFILE;
 241                                 else
 242                                         lex_class = PRINTABLE;
 243                         }
 244                 }
 245         } while (lex_class & IGNORE);
 246         return c;
 247 }
 248
 249 #define AO_LISP_TOKEN_MAX       32
 250
 251 static char     token_string[AO_LISP_TOKEN_MAX];
 252 static int      token_int;
 253 static int      token_len;
 254
 255 static inline void add_token(int c) {
 256         if (c && token_len < AO_LISP_TOKEN_MAX - 1)
 257                 token_string[token_len++] = c;
 258 }
 259
 260 static inline void end_token(void) {
 261         token_string[token_len] = '\0';
 262 }
 263
 264 static int
 265 _lex(void)
 266 {
 267         int     c;
 268
 269         token_len = 0;
 270         for (;;) {
 271                 c = lexc();
 272                 if (lex_class & ENDOFFILE)
 273                         return END;
 274
 275                 if (lex_class & WHITE)
 276                         continue;
 277
 278                 if (lex_class & COMMENT) {
 279                         while ((c = lexc()) != '\n') {
 280                                 if (lex_class & ENDOFFILE)
 281                                         return END;
 282                         }
 283                         continue;
 284                 }
 285
 286                 if (lex_class & (BRA|KET|QUOTEC)) {
 287                         add_token(c);
 288                         end_token();
 289                         switch (c) {
 290                         case '(':
 291                                 return OPEN;
 292                         case ')':
 293                                 return CLOSE;
 294                         case '\'':
 295                                 return QUOTE;
 296                         }
 297                 }
 298                 if (lex_class & (DOTC)) {
 299                         add_token(c);
 300                         end_token();
 301                         return DOT;
 302                 }
 303                 if (lex_class & TWIDDLE) {
 304                         token_int = lexc();
 305                         return NUM;
 306                 }
 307                 if (lex_class & STRINGC) {
 308                         for (;;) {
 309                                 c = lexc();
 310                                 if (lex_class & (STRINGC|ENDOFFILE)) {
 311                                         end_token();
 312                                         return STRING;
 313                                 }
 314                                 add_token(c);
 315                         }
 316                 }
 317                 if (lex_class & PRINTABLE) {
 318                         int     isnum;
 319                         int     hasdigit;
 320                         int     isneg;
 321
 322                         isnum = 1;
 323                         hasdigit = 0;
 324                         token_int = 0;
 325                         isneg = 0;
 326                         for (;;) {
 327                                 if (!(lex_class & NUMBER)) {
 328                                         isnum = 0;
 329                                 } else {
 330                                         if (token_len != 0 &&
 331                                             (lex_class & SIGN))
 332                                         {
 333                                                 isnum = 0;
 334                                         }
 335                                         if (c == '-')
 336                                                 isneg = 1;
 337                                         if (lex_class & DIGIT) {
 338                                                 hasdigit = 1;
 339                                                 if (isnum)
 340                                                         token_int = token_int * 10 + c - '0';
 341                                         }
 342                                 }
 343                                 add_token (c);
 344                                 c = lexc ();
 345                                 if (lex_class & (NOTNAME)) {
 346 //                                      if (lex_class & ENDOFFILE)
 347 //                                              clearerr (f);
 348                                         lex_unget(c);
 349                                         end_token ();
 350                                         if (isnum && hasdigit) {
 351                                                 if (isneg)
 352                                                         token_int = -token_int;
 353                                                 return NUM;
 354                                         }
 355                                         return NAME;
 356                                 }
 357                         }
 358
 359                 }
 360         }
 361 }
 362
 363 static inline int lex(void)
 364 {
 365         int     parse_token = _lex();
 366         DBGI("token %d (%s)\n", parse_token, token_string);
 367         return parse_token;
 368 }
 369
 370 static int parse_token;
 371
 372 struct ao_lisp_cons     *ao_lisp_read_cons;
 373 struct ao_lisp_cons     *ao_lisp_read_cons_tail;
 374 struct ao_lisp_cons     *ao_lisp_read_stack;
 375
 376 #define READ_IN_QUOTE   0x01
 377 #define READ_SAW_DOT    0x02
 378 #define READ_DONE_DOT   0x04
 379
 380 static int
 381 push_read_stack(int cons, int read_state)
 382 {
 383         DBGI("push read stack %p 0x%x\n", ao_lisp_read_cons, read_state);
 384         DBG_IN();
 385         if (cons) {
 386                 ao_lisp_read_stack = ao_lisp_cons_cons(ao_lisp_cons_poly(ao_lisp_read_cons),
 387                                                        ao_lisp__cons(ao_lisp_int_poly(read_state),
 388                                                                      ao_lisp_cons_poly(ao_lisp_read_stack)));
 389                 if (!ao_lisp_read_stack)
 390                         return 0;
 391         }
 392         ao_lisp_read_cons = NULL;
 393         ao_lisp_read_cons_tail = NULL;
 394         return 1;
 395 }
 396
 397 static int
 398 pop_read_stack(int cons)
 399 {
 400         int     read_state = 0;
 401         if (cons) {
 402                 ao_lisp_read_cons = ao_lisp_poly_cons(ao_lisp_read_stack->car);
 403                 ao_lisp_read_stack = ao_lisp_poly_cons(ao_lisp_read_stack->cdr);
 404                 read_state = ao_lisp_poly_int(ao_lisp_read_stack->car);
 405                 ao_lisp_read_stack = ao_lisp_poly_cons(ao_lisp_read_stack->cdr);
 406                 for (ao_lisp_read_cons_tail = ao_lisp_read_cons;
 407                      ao_lisp_read_cons_tail && ao_lisp_read_cons_tail->cdr;
 408                      ao_lisp_read_cons_tail = ao_lisp_poly_cons(ao_lisp_read_cons_tail->cdr))
 409                         ;
 410         } else {
 411                 ao_lisp_read_cons = 0;
 412                 ao_lisp_read_cons_tail = 0;
 413                 ao_lisp_read_stack = 0;
 414         }
 415         DBG_OUT();
 416         DBGI("pop read stack %p %d\n", ao_lisp_read_cons, read_state);
 417         return read_state;
 418 }
 419
 420 ao_poly
 421 ao_lisp_read(void)
 422 {
 423         struct ao_lisp_atom     *atom;
 424         char                    *string;
 425         int                     cons;
 426         int                     read_state;
 427         ao_poly                 v;
 428
 429
 430         cons = 0;
 431         read_state = 0;
 432         ao_lisp_read_cons = ao_lisp_read_cons_tail = ao_lisp_read_stack = 0;
 433         for (;;) {
 434                 parse_token = lex();
 435                 while (parse_token == OPEN) {
 436                         if (!push_read_stack(cons, read_state))
 437                                 return AO_LISP_NIL;
 438                         cons++;
 439                         read_state = 0;
 440                         parse_token = lex();
 441                 }
 442
 443                 switch (parse_token) {
 444                 case END:
 445                 default:
 446                         if (cons)
 447                                 ao_lisp_error(AO_LISP_EOF, "unexpected end of file");
 448                         return _ao_lisp_atom_eof;
 449                         break;
 450                 case NAME:
 451                         atom = ao_lisp_atom_intern(token_string);
 452                         if (atom)
 453                                 v = ao_lisp_atom_poly(atom);
 454                         else
 455                                 v = AO_LISP_NIL;
 456                         break;
 457                 case NUM:
 458                         v = ao_lisp_int_poly(token_int);
 459                         break;
 460                 case STRING:
 461                         string = ao_lisp_string_copy(token_string);
 462                         if (string)
 463                                 v = ao_lisp_string_poly(string);
 464                         else
 465                                 v = AO_LISP_NIL;
 466                         break;
 467                 case QUOTE:
 468                         if (!push_read_stack(cons, read_state))
 469                                 return AO_LISP_NIL;
 470                         cons++;
 471                         read_state |= READ_IN_QUOTE;
 472                         v = _ao_lisp_atom_quote;
 473                         break;
 474                 case CLOSE:
 475                         if (!cons) {
 476                                 v = AO_LISP_NIL;
 477                                 break;
 478                         }
 479                         v = ao_lisp_cons_poly(ao_lisp_read_cons);
 480                         --cons;
 481                         read_state = pop_read_stack(cons);
 482                         break;
 483                 case DOT:
 484                         if (!cons) {
 485                                 ao_lisp_error(AO_LISP_INVALID, ". outside of cons");
 486                                 return AO_LISP_NIL;
 487                         }
 488                         if (!ao_lisp_read_cons) {
 489                                 ao_lisp_error(AO_LISP_INVALID, ". first in cons");
 490                                 return AO_LISP_NIL;
 491                         }
 492                         read_state |= READ_SAW_DOT;
 493                         continue;
 494                 }
 495
 496                 /* loop over QUOTE ends */
 497                 for (;;) {
 498                         if (!cons)
 499                                 return v;
 500
 501                         if (read_state & READ_DONE_DOT) {
 502                                 ao_lisp_error(AO_LISP_INVALID, ". not last in cons");
 503                                 return AO_LISP_NIL;
 504                         }
 505
 506                         if (read_state & READ_SAW_DOT) {
 507                                 read_state |= READ_DONE_DOT;
 508                                 ao_lisp_read_cons_tail->cdr = v;
 509                         } else {
 510                                 struct ao_lisp_cons     *read = ao_lisp_cons_cons(v, AO_LISP_NIL);
 511                                 if (!read)
 512                                         return AO_LISP_NIL;
 513
 514                                 if (ao_lisp_read_cons_tail)
 515                                         ao_lisp_read_cons_tail->cdr = ao_lisp_cons_poly(read);
 516                                 else
 517                                         ao_lisp_read_cons = read;
 518                                 ao_lisp_read_cons_tail = read;
 519                         }
 520
 521                         if (!(read_state & READ_IN_QUOTE) || !ao_lisp_read_cons->cdr)
 522                                 break;
 523
 524                         v = ao_lisp_cons_poly(ao_lisp_read_cons);
 525                         --cons;
 526                         read_state = pop_read_stack(cons);
 527                 }
 528         }
 529         return v;
 530 }