sys/src/cmd/cpp/lex.c

   1 #include <u.h>
   2 #include <libc.h>
   3 #include <stdio.h>
   4 #include "cpp.h"
   5
   6 /*
   7  * lexical FSM encoding
   8  *   when in state state, and one of the characters
   9  *   in ch arrives, enter nextstate.
  10  *   States >= S_SELF are either final, or at least require special action.
  11  *   In 'fsm' there is a line for each state X charset X nextstate.
  12  *   List chars that overwrite previous entries later (e.g. C_ALPH
  13  *   can be overridden by '_' by a later entry; and C_XX is the
  14  *   the universal set, and should always be first.
  15  *   States above S_SELF are represented in the big table as negative values.
  16  *   S_SELF and S_SELFB encode the resulting token type in the upper bits.
  17  *   These actions differ in that S_SELF doesn't have a lookahead char,
  18  *   S_SELFB does.
  19  *
  20  *   The encoding is blown out into a big table for time-efficiency.
  21  *   Entries have
  22  *      nextstate: 6 bits; ?\ marker: 1 bit; tokentype: 9 bits.
  23  */
  24
  25 #define MAXSTATE 32
  26 #define ACT(tok,act)    ((tok<<7)+act)
  27 #define QBSBIT  0100
  28 #define GETACT(st)      (st>>7)&0x1ff
  29
  30 #define UTF2(c)         ((c)>=0xA0 && (c)<0xE0)         /* 2-char UTF seq */
  31 #define UTF3(c)         ((c)>=0xE0 && (c)<0xF0)         /* 3-char UTF seq */
  32
  33 /* character classes */
  34 #define C_WS    1
  35 #define C_ALPH  2
  36 #define C_NUM   3
  37 #define C_EOF   4
  38 #define C_XX    5
  39
  40 enum state {
  41         START=0, NUM1, NUM2, NUM3, ID1, ST1, ST2, ST3, COM1, COM2, COM3, COM4,
  42         CC1, CC2, WS1, PLUS1, MINUS1, STAR1, SLASH1, PCT1, SHARP1,
  43         CIRC1, GT1, GT2, LT1, LT2, OR1, AND1, ASG1, NOT1, DOTS1,
  44         S_SELF=MAXSTATE, S_SELFB, S_EOF, S_NL, S_EOFSTR,
  45         S_STNL, S_COMNL, S_EOFCOM, S_COMMENT, S_EOB, S_WS, S_NAME
  46 };
  47
  48 int     tottok;
  49 int     tokkind[256];
  50 struct  fsm {
  51         int     state;          /* if in this state */
  52         uchar   ch[4];          /* and see one of these characters */
  53         int     nextstate;      /* enter this state if +ve */
  54 };
  55
  56 /*const*/ struct fsm fsm[] = {
  57         /* start state */
  58         START,  { C_XX },       ACT(UNCLASS,S_SELF),
  59         START,  { ' ', '\t', '\v', '\r' },      WS1,
  60         START,  { C_NUM },      NUM1,
  61         START,  { '.' },        NUM3,
  62         START,  { C_ALPH },     ID1,
  63         START,  { 'L' },        ST1,
  64         START,  { '"' },        ST2,
  65         START,  { '\'' },       CC1,
  66         START,  { '/' },        COM1,
  67         START,  { EOFC },       S_EOF,
  68         START,  { '\n' },       S_NL,
  69         START,  { '-' },        MINUS1,
  70         START,  { '+' },        PLUS1,
  71         START,  { '<' },        LT1,
  72         START,  { '>' },        GT1,
  73         START,  { '=' },        ASG1,
  74         START,  { '!' },        NOT1,
  75         START,  { '&' },        AND1,
  76         START,  { '|' },        OR1,
  77         START,  { '#' },        SHARP1,
  78         START,  { '%' },        PCT1,
  79         START,  { '[' },        ACT(SBRA,S_SELF),
  80         START,  { ']' },        ACT(SKET,S_SELF),
  81         START,  { '(' },        ACT(LP,S_SELF),
  82         START,  { ')' },        ACT(RP,S_SELF),
  83         START,  { '*' },        STAR1,
  84         START,  { ',' },        ACT(COMMA,S_SELF),
  85         START,  { '?' },        ACT(QUEST,S_SELF),
  86         START,  { ':' },        ACT(COLON,S_SELF),
  87         START,  { ';' },        ACT(SEMIC,S_SELF),
  88         START,  { '{' },        ACT(CBRA,S_SELF),
  89         START,  { '}' },        ACT(CKET,S_SELF),
  90         START,  { '~' },        ACT(TILDE,S_SELF),
  91         START,  { '^' },        CIRC1,
  92
  93         /* saw a digit */
  94         NUM1,   { C_XX },       ACT(NUMBER,S_SELFB),
  95         NUM1,   { C_NUM, C_ALPH, '.' }, NUM1,
  96         NUM1,   { 'E', 'e' },   NUM2,
  97         NUM1,   { '_' },        ACT(NUMBER,S_SELFB),
  98
  99         /* saw possible start of exponent, digits-e */
 100         NUM2,   { C_XX },       ACT(NUMBER,S_SELFB),
 101         NUM2,   { '+', '-' },   NUM1,
 102         NUM2,   { C_NUM, C_ALPH },      NUM1,
 103         NUM2,   { '_' },        ACT(NUMBER,S_SELFB),
 104
 105         /* saw a '.', which could be a number or an operator */
 106         NUM3,   { C_XX },       ACT(DOT,S_SELFB),
 107         NUM3,   { '.' },        DOTS1,
 108         NUM3,   { C_NUM },      NUM1,
 109
 110         DOTS1,  { C_XX },       ACT(UNCLASS, S_SELFB),
 111         DOTS1,  { C_NUM },      NUM1,
 112         DOTS1,  { '.' },        ACT(ELLIPS, S_SELF),
 113
 114         /* saw a letter or _ */
 115         ID1,    { C_XX },       ACT(NAME,S_NAME),
 116         ID1,    { C_ALPH, C_NUM },      ID1,
 117
 118         /* saw L (start of wide string?) */
 119         ST1,    { C_XX },       ACT(NAME,S_NAME),
 120         ST1,    { C_ALPH, C_NUM },      ID1,
 121         ST1,    { '"' },        ST2,
 122         ST1,    { '\'' },       CC1,
 123
 124         /* saw " beginning string */
 125         ST2,    { C_XX },       ST2,
 126         ST2,    { '"' },        ACT(STRING, S_SELF),
 127         ST2,    { '\\' },       ST3,
 128         ST2,    { '\n' },       S_STNL,
 129         ST2,    { EOFC },       S_EOFSTR,
 130
 131         /* saw \ in string */
 132         ST3,    { C_XX },       ST2,
 133         ST3,    { '\n' },       S_STNL,
 134         ST3,    { EOFC },       S_EOFSTR,
 135
 136         /* saw ' beginning character const */
 137         CC1,    { C_XX },       CC1,
 138         CC1,    { '\'' },       ACT(CCON, S_SELF),
 139         CC1,    { '\\' },       CC2,
 140         CC1,    { '\n' },       S_STNL,
 141         CC1,    { EOFC },       S_EOFSTR,
 142
 143         /* saw \ in ccon */
 144         CC2,    { C_XX },       CC1,
 145         CC2,    { '\n' },       S_STNL,
 146         CC2,    { EOFC },       S_EOFSTR,
 147
 148         /* saw /, perhaps start of comment */
 149         COM1,   { C_XX },       ACT(SLASH, S_SELFB),
 150         COM1,   { '=' },        ACT(ASSLASH, S_SELF),
 151         COM1,   { '*' },        COM2,
 152         COM1,   { '/' },        COM4,
 153
 154         /* saw "/*", start of comment */
 155         COM2,   { C_XX },       COM2,
 156         COM2,   { '\n' },       S_COMNL,
 157         COM2,   { '*' },        COM3,
 158         COM2,   { EOFC },       S_EOFCOM,
 159
 160         /* saw the * possibly ending a comment */
 161         COM3,   { C_XX },       COM2,
 162         COM3,   { '\n' },       S_COMNL,
 163         COM3,   { '*' },        COM3,
 164         COM3,   { '/' },        S_COMMENT,
 165         COM3,   { EOFC },       S_EOFCOM,
 166
 167         /* // comment */
 168         COM4,   { C_XX },       COM4,
 169         COM4,   { '\n' },       S_NL,
 170         COM4,   { EOFC },       S_EOFCOM,
 171
 172         /* saw white space, eat it up */
 173         WS1,    { C_XX },       S_WS,
 174         WS1,    { ' ', '\t', '\v', '\r'},       WS1,
 175
 176         /* saw -, check --, -=, -> */
 177         MINUS1, { C_XX },       ACT(MINUS, S_SELFB),
 178         MINUS1, { '-' },        ACT(MMINUS, S_SELF),
 179         MINUS1, { '=' },        ACT(ASMINUS,S_SELF),
 180         MINUS1, { '>' },        ACT(ARROW,S_SELF),
 181
 182         /* saw +, check ++, += */
 183         PLUS1,  { C_XX },       ACT(PLUS, S_SELFB),
 184         PLUS1,  { '+' },        ACT(PPLUS, S_SELF),
 185         PLUS1,  { '=' },        ACT(ASPLUS, S_SELF),
 186
 187         /* saw <, check <<, <<=, <= */
 188         LT1,    { C_XX },       ACT(LT, S_SELFB),
 189         LT1,    { '<' },        LT2,
 190         LT1,    { '=' },        ACT(LEQ, S_SELF),
 191         LT2,    { C_XX },       ACT(LSH, S_SELFB),
 192         LT2,    { '=' },        ACT(ASLSH, S_SELF),
 193
 194         /* saw >, check >>, >>=, >= */
 195         GT1,    { C_XX },       ACT(GT, S_SELFB),
 196         GT1,    { '>' },        GT2,
 197         GT1,    { '=' },        ACT(GEQ, S_SELF),
 198         GT2,    { C_XX },       ACT(RSH, S_SELFB),
 199         GT2,    { '=' },        ACT(ASRSH, S_SELF),
 200
 201         /* = */
 202         ASG1,   { C_XX },       ACT(ASGN, S_SELFB),
 203         ASG1,   { '=' },        ACT(EQ, S_SELF),
 204
 205         /* ! */
 206         NOT1,   { C_XX },       ACT(NOT, S_SELFB),
 207         NOT1,   { '=' },        ACT(NEQ, S_SELF),
 208
 209         /* & */
 210         AND1,   { C_XX },       ACT(AND, S_SELFB),
 211         AND1,   { '&' },        ACT(LAND, S_SELF),
 212         AND1,   { '=' },        ACT(ASAND, S_SELF),
 213
 214         /* | */
 215         OR1,    { C_XX },       ACT(OR, S_SELFB),
 216         OR1,    { '|' },        ACT(LOR, S_SELF),
 217         OR1,    { '=' },        ACT(ASOR, S_SELF),
 218
 219         /* # */
 220         SHARP1, { C_XX },       ACT(SHARP, S_SELFB),
 221         SHARP1, { '#' },        ACT(DSHARP, S_SELF),
 222
 223         /* % */
 224         PCT1,   { C_XX },       ACT(PCT, S_SELFB),
 225         PCT1,   { '=' },        ACT(ASPCT, S_SELF),
 226
 227         /* * */
 228         STAR1,  { C_XX },       ACT(STAR, S_SELFB),
 229         STAR1,  { '=' },        ACT(ASSTAR, S_SELF),
 230
 231         /* ^ */
 232         CIRC1,  { C_XX },       ACT(CIRC, S_SELFB),
 233         CIRC1,  { '=' },        ACT(ASCIRC, S_SELF),
 234
 235         -1
 236 };
 237
 238 /* first index is char, second is state */
 239 /* increase #states to power of 2 to encourage use of shift */
 240 short   bigfsm[256][MAXSTATE];
 241
 242 void
 243 expandlex(void)
 244 {
 245         /*const*/ struct fsm *fp;
 246         int i, j, nstate;
 247
 248         for (fp = fsm; fp->state>=0; fp++) {
 249                 for (i=0; fp->ch[i]; i++) {
 250                         nstate = fp->nextstate;
 251                         if (nstate >= S_SELF)
 252                                 nstate = ~nstate;
 253                         switch (fp->ch[i]) {
 254
 255                         case C_XX:              /* random characters */
 256                                 for (j=0; j<256; j++)
 257                                         bigfsm[j][fp->state] = nstate;
 258                                 continue;
 259                         case C_ALPH:
 260                                 for (j=0; j<=256; j++)
 261                                         if ('a'<=j&&j<='z' || 'A'<=j&&j<='Z'
 262                                           || UTF2(j) || UTF3(j) || j=='_')
 263                                                 bigfsm[j][fp->state] = nstate;
 264                                 continue;
 265                         case C_NUM:
 266                                 for (j='0'; j<='9'; j++)
 267                                         bigfsm[j][fp->state] = nstate;
 268                                 continue;
 269                         default:
 270                                 bigfsm[fp->ch[i]][fp->state] = nstate;
 271                         }
 272                 }
 273         }
 274         /* install special cases for ? (trigraphs),  \ (splicing), runes, and EOB */
 275         for (i=0; i<MAXSTATE; i++) {
 276                 for (j=0; j<0xFF; j++)
 277                         if (j=='?' || j=='\\' || UTF2(j) || UTF3(j)) {
 278                                 if (bigfsm[j][i]>0)
 279                                         bigfsm[j][i] = ~bigfsm[j][i];
 280                                 bigfsm[j][i] &= ~QBSBIT;
 281                         }
 282                 bigfsm[EOB][i] = ~S_EOB;
 283                 if (bigfsm[EOFC][i]>=0)
 284                         bigfsm[EOFC][i] = ~S_EOF;
 285         }
 286 }
 287
 288 void
 289 fixlex(void)
 290 {
 291         /* do C++ comments? */
 292         if (Cplusplus==0)
 293                 bigfsm['/'][COM1] = bigfsm['x'][COM1];
 294 }
 295
 296 /*
 297  * fill in a row of tokens from input, terminated by NL or END
 298  * First token is put at trp->lp.
 299  * Reset is non-zero when the input buffer can be "rewound."
 300  * The value is a flag indicating that possible macros have
 301  * been seen in the row.
 302  */
 303 int
 304 gettokens(Tokenrow *trp, int reset)
 305 {
 306         register int c, state, oldstate;
 307         register uchar *ip;
 308         register Token *tp, *maxp;
 309         int runelen;
 310         Source *s = cursource;
 311         int nmac = 0;
 312         extern char outbuf[];
 313
 314         tp = trp->lp;
 315         ip = s->inp;
 316         if (reset) {
 317                 s->lineinc = 0;
 318                 if (ip>=s->inl) {               /* nothing in buffer */
 319                         s->inl = s->inb;
 320                         fillbuf(s);
 321                         ip = s->inp = s->inb;
 322                 } else if (ip >= s->inb+(3*s->ins/4)) {
 323                         memmove(s->inb, ip, 4+s->inl-ip);
 324                         s->inl = s->inb+(s->inl-ip);
 325                         ip = s->inp = s->inb;
 326                 }
 327         }
 328         maxp = &trp->bp[trp->max];
 329         runelen = 1;
 330         for (;;) {
 331            continue2:
 332                 if (tp>=maxp) {
 333                         trp->lp = tp;
 334                         tp = growtokenrow(trp);
 335                         maxp = &trp->bp[trp->max];
 336                 }
 337                 tp->type = UNCLASS;
 338                 tp->hideset = 0;
 339                 tp->t = ip;
 340                 tp->wslen = 0;
 341                 tp->flag = 0;
 342                 state = START;
 343                 for (;;) {
 344                         oldstate = state;
 345                         c = *ip;
 346                         if ((state = bigfsm[c][state]) >= 0) {
 347                                 ip += runelen;
 348                                 runelen = 1;
 349                                 continue;
 350                         }
 351                         state = ~state;
 352                 reswitch:
 353                         switch (state&0177) {
 354                         case S_SELF:
 355                                 ip += runelen;
 356                                 runelen = 1;
 357                         case S_SELFB:
 358                                 tp->type = GETACT(state);
 359                                 tp->len = ip - tp->t;
 360                                 tp++;
 361                                 goto continue2;
 362
 363                         case S_NAME:    /* like S_SELFB but with nmac check */
 364                                 tp->type = NAME;
 365                                 tp->len = ip - tp->t;
 366                                 nmac |= quicklook(tp->t[0], tp->len>1?tp->t[1]:0);
 367                                 tp++;
 368                                 goto continue2;
 369
 370                         case S_WS:
 371                                 tp->wslen = ip - tp->t;
 372                                 tp->t = ip;
 373                                 state = START;
 374                                 continue;
 375
 376                         default:
 377                                 if ((state&QBSBIT)==0) {
 378                                         ip += runelen;
 379                                         runelen = 1;
 380                                         continue;
 381                                 }
 382                                 state &= ~QBSBIT;
 383                                 s->inp = ip;
 384                                 if (c=='?') {   /* check trigraph */
 385                                         if (trigraph(s)) {
 386                                                 state = oldstate;
 387                                                 continue;
 388                                         }
 389                                         goto reswitch;
 390                                 }
 391                                 if (c=='\\') { /* line-folding */
 392                                         if (foldline(s)) {
 393                                                 s->lineinc++;
 394                                                 state = oldstate;
 395                                                 continue;
 396                                         }
 397                                         goto reswitch;
 398                                 }
 399                                 if (UTF2(c)) {
 400                                         runelen = 2;
 401                                         goto reswitch;
 402                                 }
 403                                 if (UTF3(c)) {
 404                                         runelen = 3;
 405                                         goto reswitch;
 406                                 }
 407                                 error(WARNING, "Lexical botch in cpp");
 408                                 ip += runelen;
 409                                 runelen = 1;
 410                                 continue;
 411
 412                         case S_EOB:
 413                                 s->inp = ip;
 414                                 fillbuf(cursource);
 415                                 state = oldstate;
 416                                 continue;
 417
 418                         case S_EOF:
 419                                 tp->type = END;
 420                                 tp->len = 0;
 421                                 s->inp = ip;
 422                                 if (tp!=trp->bp && (tp-1)->type!=NL && cursource->fd!=-1)
 423                                         error(WARNING,"No newline at end of file");
 424                                 trp->lp = tp+1;
 425                                 return nmac;
 426
 427                         case S_STNL:
 428                                 error(ERROR, "Unterminated string or char const");
 429                         case S_NL:
 430                                 tp->t = ip;
 431                                 tp->type = NL;
 432                                 tp->len = 1;
 433                                 tp->wslen = 0;
 434                                 s->lineinc++;
 435                                 s->inp = ip+1;
 436                                 trp->lp = tp+1;
 437                                 return nmac;
 438
 439                         case S_EOFSTR:
 440                                 error(FATAL, "EOF in string or char constant");
 441                                 break;
 442
 443                         case S_COMNL:
 444                                 s->lineinc++;
 445                                 state = COM2;
 446                                 ip += runelen;
 447                                 runelen = 1;
 448                                 if (ip >= s->inb+(7*s->ins/8)) { /* very long comment */
 449                                         memmove(tp->t, ip, 4+s->inl-ip);
 450                                         s->inl -= ip-tp->t;
 451                                         ip = tp->t+1;
 452                                 }
 453                                 continue;
 454
 455                         case S_EOFCOM:
 456                                 error(WARNING, "EOF inside comment");
 457                                 --ip;
 458                         case S_COMMENT:
 459                                 ++ip;
 460                                 tp->t = ip;
 461                                 tp->t[-1] = ' ';
 462                                 tp->wslen = 1;
 463                                 state = START;
 464                                 continue;
 465                         }
 466                         break;
 467                 }
 468                 ip += runelen;
 469                 runelen = 1;
 470                 tp->len = ip - tp->t;
 471                 tp++;
 472         }
 473 }
 474
 475 /* have seen ?; handle the trigraph it starts (if any) else 0 */
 476 int
 477 trigraph(Source *s)
 478 {
 479         int c;
 480
 481         while (s->inp+2 >= s->inl && fillbuf(s)!=EOF)
 482                 ;
 483         if (s->inp[1]!='?')
 484                 return 0;
 485         c = 0;
 486         switch(s->inp[2]) {
 487         case '=':
 488                 c = '#'; break;
 489         case '(':
 490                 c = '['; break;
 491         case '/':
 492                 c = '\\'; break;
 493         case ')':
 494                 c = ']'; break;
 495         case '\'':
 496                 c = '^'; break;
 497         case '<':
 498                 c = '{'; break;
 499         case '!':
 500                 c = '|'; break;
 501         case '>':
 502                 c = '}'; break;
 503         case '-':
 504                 c = '~'; break;
 505         }
 506         if (c) {
 507                 *s->inp = c;
 508                 memmove(s->inp+1, s->inp+3, s->inl-s->inp+2);
 509                 s->inl -= 2;
 510         }
 511         return c;
 512 }
 513
 514 int
 515 foldline(Source *s)
 516 {
 517         int ncr = 0;
 518
 519 recheck:
 520         while (s->inp+1 >= s->inl && fillbuf(s)!=EOF)
 521                 ;
 522         if (s->inp[ncr+1] == '\r') {    /* nonstandardly, ignore CR before line-folding */
 523                 ncr++;
 524                 goto recheck;
 525         }
 526         if (s->inp[ncr+1] == '\n') {
 527                 memmove(s->inp, s->inp+2+ncr, s->inl-s->inp+3-ncr);
 528                 s->inl -= 2+ncr;
 529                 return 1;
 530         }
 531         return 0;
 532 }
 533
 534 int
 535 fillbuf(Source *s)
 536 {
 537         int n;
 538
 539         while((char *)s->inl+s->ins/8 > (char *)s->inb+s->ins) {
 540                 int l = s->inl - s->inb;
 541                 int p = s->inp - s->inb;
 542                 if(l < 0)
 543                         error(FATAL, "negative end of input!?");
 544                 if(p < 0)
 545                         error(FATAL, "negative input pointer!?");
 546                 /* double the buffer size and try again */
 547                 s->ins *= 2;
 548                 s->inb = dorealloc(s->inb, s->ins);
 549                 s->inl = s->inb + l;
 550                 s->inp = s->inb + p;
 551         }
 552         if (s->fd<0 || (n=read(s->fd, (char *)s->inl, s->ins/8)) <= 0)
 553                 n = 0;
 554         if ((*s->inp&0xff) == EOB) /* sentinel character appears in input */
 555                 *s->inp = EOFC;
 556         s->inl += n;
 557         s->inl[0] = s->inl[1]= s->inl[2]= s->inl[3] = EOB;
 558         if (n==0) {
 559                 s->inl[0] = s->inl[1]= s->inl[2]= s->inl[3] = EOFC;
 560                 return EOF;
 561         }
 562         return 0;
 563 }
 564
 565 /*
 566  * Push down to new source of characters.
 567  * If fd>0 and str==NULL, then from a file `name';
 568  * if fd==-1 and str, then from the string.
 569  */
 570 Source *
 571 setsource(char *name, int fd, char *str)
 572 {
 573         Source *s = new(Source);
 574         int len;
 575
 576         s->line = 1;
 577         s->lineinc = 0;
 578         s->fd = fd;
 579         s->filename = name;
 580         s->next = cursource;
 581         s->ifdepth = 0;
 582         cursource = s;
 583         /* slop at right for EOB */
 584         if (str) {
 585                 len = strlen(str);
 586                 s->inb = domalloc(len+4);
 587                 s->inp = s->inb;
 588                 strncpy((char *)s->inp, str, len);
 589         } else {
 590                 Dir *d;
 591                 int junk;
 592                 ulong length = 0;
 593                 d = dirfstat(fd);
 594                 if (d != nil) {
 595                         length = d->length;
 596                         free(d);
 597                 }
 598                 junk = length;
 599                 if (junk<INS)
 600                         junk = INS;
 601                 s->inb = domalloc((junk)+4);
 602                 s->inp = s->inb;
 603                 len = 0;
 604         }
 605
 606         s->ins = INS;
 607         s->inl = s->inp+len;
 608         s->inl[0] = s->inl[1] = EOB;
 609         return s;
 610 }
 611
 612 void
 613 unsetsource(void)
 614 {
 615         Source *s = cursource;
 616
 617         if (s->fd>=0) {
 618                 close(s->fd);
 619                 dofree(s->inb);
 620         }
 621         cursource = s->next;
 622         dofree(s);
 623 }