1 /*
2 * *****************************************************************************
3 *
4 * SPDX-License-Identifier: BSD-2-Clause
5 *
6 * Copyright (c) 2018-2023 Gavin D. Howard and contributors.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions are met:
10 *
11 * * Redistributions of source code must retain the above copyright notice, this
12 * list of conditions and the following disclaimer.
13 *
14 * * Redistributions in binary form must reproduce the above copyright notice,
15 * this list of conditions and the following disclaimer in the documentation
16 * and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
22 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
29 *
30 * *****************************************************************************
31 *
32 * The lexer for bc.
33 *
34 */
35
36 #if BC_ENABLED
37
38 #include <assert.h>
39 #include <ctype.h>
40 #include <string.h>
41
42 #include <bc.h>
43 #include <vm.h>
44
45 /**
46 * Lexes an identifier, which may be a keyword.
47 * @param l The lexer.
48 */
49 static void
bc_lex_identifier(BcLex * l)50 bc_lex_identifier(BcLex* l)
51 {
52 // We already passed the first character, so we need to be sure to include
53 // it.
54 const char* buf = l->buf + l->i - 1;
55 size_t i;
56
57 // This loop is simply checking for keywords.
58 for (i = 0; i < bc_lex_kws_len; ++i)
59 {
60 const BcLexKeyword* kw = bc_lex_kws + i;
61 size_t n = BC_LEX_KW_LEN(kw);
62
63 if (!strncmp(buf, kw->name, n) && !isalnum(buf[n]) && buf[n] != '_')
64 {
65 // If the keyword has been redefined, and redefinition is allowed
66 // (it is not allowed for builtin libraries), break out of the loop
67 // and use it as a name. This depends on the argument parser to
68 // ensure that only non-POSIX keywords get redefined.
69 if (!vm->no_redefine && vm->redefined_kws[i]) break;
70
71 l->t = BC_LEX_KW_AUTO + (BcLexType) i;
72
73 // Warn or error, as appropriate for the mode, if the keyword is not
74 // in the POSIX standard.
75 if (!BC_LEX_KW_POSIX(kw)) bc_lex_verr(l, BC_ERR_POSIX_KW, kw->name);
76
77 // We minus 1 because the index has already been incremented.
78 l->i += n - 1;
79
80 // Already have the token; bail.
81 return;
82 }
83 }
84
85 // If not a keyword, parse the name.
86 bc_lex_name(l);
87
88 // POSIX doesn't allow identifiers that are more than one character, so we
89 // might have to warn or error here too.
90 if (BC_ERR(l->str.len - 1 > 1))
91 {
92 bc_lex_verr(l, BC_ERR_POSIX_NAME_LEN, l->str.v);
93 }
94 }
95
96 /**
97 * Parses a bc string. This is separate from dc strings because dc strings need
98 * to be balanced.
99 * @param l The lexer.
100 */
101 static void
bc_lex_string(BcLex * l)102 bc_lex_string(BcLex* l)
103 {
104 // We need to keep track of newlines to increment them properly.
105 size_t len, nlines, i;
106 const char* buf;
107 char c;
108 bool got_more;
109
110 l->t = BC_LEX_STR;
111
112 do
113 {
114 nlines = 0;
115 buf = l->buf;
116 got_more = false;
117
118 assert(vm->mode != BC_MODE_STDIN || buf == vm->buffer.v);
119
120 // Fortunately for us, bc doesn't escape quotes. Instead, the equivalent
121 // is '\q', which makes this loop simpler.
122 for (i = l->i; (c = buf[i]) && c != '"'; ++i)
123 {
124 nlines += (c == '\n');
125 }
126
127 if (BC_ERR(c == '\0') && !vm->eof && l->mode != BC_MODE_FILE)
128 {
129 got_more = bc_lex_readLine(l);
130 }
131 }
132 while (got_more && c != '"');
133
134 // If the string did not end properly, barf.
135 if (c != '"')
136 {
137 l->i = i;
138 bc_lex_err(l, BC_ERR_PARSE_STRING);
139 }
140
141 // Set the temp string to the parsed string.
142 len = i - l->i;
143 bc_vec_string(&l->str, len, l->buf + l->i);
144
145 l->i = i + 1;
146 l->line += nlines;
147 }
148
149 /**
150 * This function takes a lexed operator and checks to see if it's the assignment
151 * version, setting the token appropriately.
152 * @param l The lexer.
153 * @param with The token to assign if it is an assignment operator.
154 * @param without The token to assign if it is not an assignment operator.
155 */
156 static void
bc_lex_assign(BcLex * l,BcLexType with,BcLexType without)157 bc_lex_assign(BcLex* l, BcLexType with, BcLexType without)
158 {
159 if (l->buf[l->i] == '=')
160 {
161 l->i += 1;
162 l->t = with;
163 }
164 else l->t = without;
165 }
166
167 void
bc_lex_token(BcLex * l)168 bc_lex_token(BcLex* l)
169 {
170 // We increment here. This means that all lexing needs to take that into
171 // account, such as when parsing an identifier. If we don't, the first
172 // character of every identifier would be missing.
173 char c = l->buf[l->i++], c2;
174
175 BC_SIG_ASSERT_LOCKED;
176
177 // This is the workhorse of the lexer.
178 switch (c)
179 {
180 case '\0':
181 case '\n':
182 case '\t':
183 case '\v':
184 case '\f':
185 case '\r':
186 case ' ':
187 {
188 bc_lex_commonTokens(l, c);
189 break;
190 }
191
192 case '!':
193 {
194 // Even though it's not an assignment, we can use this.
195 bc_lex_assign(l, BC_LEX_OP_REL_NE, BC_LEX_OP_BOOL_NOT);
196
197 // POSIX doesn't allow boolean not.
198 if (l->t == BC_LEX_OP_BOOL_NOT)
199 {
200 bc_lex_verr(l, BC_ERR_POSIX_BOOL, "!");
201 }
202
203 break;
204 }
205
206 case '"':
207 {
208 bc_lex_string(l);
209 break;
210 }
211
212 case '#':
213 {
214 // POSIX does not allow line comments.
215 bc_lex_err(l, BC_ERR_POSIX_COMMENT);
216 bc_lex_lineComment(l);
217 break;
218 }
219
220 case '%':
221 {
222 bc_lex_assign(l, BC_LEX_OP_ASSIGN_MODULUS, BC_LEX_OP_MODULUS);
223 break;
224 }
225
226 case '&':
227 {
228 c2 = l->buf[l->i];
229
230 // Either we have boolean and or an error. And boolean and is not
231 // allowed by POSIX.
232 if (BC_NO_ERR(c2 == '&'))
233 {
234 bc_lex_verr(l, BC_ERR_POSIX_BOOL, "&&");
235
236 l->i += 1;
237 l->t = BC_LEX_OP_BOOL_AND;
238 }
239 else bc_lex_invalidChar(l, c);
240
241 break;
242 }
243 #if BC_ENABLE_EXTRA_MATH
244 case '$':
245 {
246 l->t = BC_LEX_OP_TRUNC;
247 break;
248 }
249
250 case '@':
251 {
252 bc_lex_assign(l, BC_LEX_OP_ASSIGN_PLACES, BC_LEX_OP_PLACES);
253 break;
254 }
255 #endif // BC_ENABLE_EXTRA_MATH
256 case '(':
257 case ')':
258 {
259 l->t = (BcLexType) (c - '(' + BC_LEX_LPAREN);
260 break;
261 }
262
263 case '*':
264 {
265 bc_lex_assign(l, BC_LEX_OP_ASSIGN_MULTIPLY, BC_LEX_OP_MULTIPLY);
266 break;
267 }
268
269 case '+':
270 {
271 c2 = l->buf[l->i];
272
273 // Have to check for increment first.
274 if (c2 == '+')
275 {
276 l->i += 1;
277 l->t = BC_LEX_OP_INC;
278 }
279 else bc_lex_assign(l, BC_LEX_OP_ASSIGN_PLUS, BC_LEX_OP_PLUS);
280 break;
281 }
282
283 case ',':
284 {
285 l->t = BC_LEX_COMMA;
286 break;
287 }
288
289 case '-':
290 {
291 c2 = l->buf[l->i];
292
293 // Have to check for decrement first.
294 if (c2 == '-')
295 {
296 l->i += 1;
297 l->t = BC_LEX_OP_DEC;
298 }
299 else bc_lex_assign(l, BC_LEX_OP_ASSIGN_MINUS, BC_LEX_OP_MINUS);
300 break;
301 }
302
303 case '.':
304 {
305 c2 = l->buf[l->i];
306
307 // If it's alone, it's an alias for last.
308 if (BC_LEX_NUM_CHAR(c2, true, false)) bc_lex_number(l, c);
309 else
310 {
311 l->t = BC_LEX_KW_LAST;
312 bc_lex_err(l, BC_ERR_POSIX_DOT);
313 }
314
315 break;
316 }
317
318 case '/':
319 {
320 c2 = l->buf[l->i];
321 if (c2 == '*') bc_lex_comment(l);
322 else bc_lex_assign(l, BC_LEX_OP_ASSIGN_DIVIDE, BC_LEX_OP_DIVIDE);
323 break;
324 }
325
326 case '0':
327 case '1':
328 case '2':
329 case '3':
330 case '4':
331 case '5':
332 case '6':
333 case '7':
334 case '8':
335 case '9':
336 case 'A':
337 case 'B':
338 case 'C':
339 case 'D':
340 case 'E':
341 case 'F':
342 // Apparently, GNU bc (and maybe others) allows any uppercase letter as
343 // a number. When single digits, they act like the ones above. When
344 // multi-digit, any letter above the input base is automatically set to
345 // the biggest allowable digit in the input base.
346 case 'G':
347 case 'H':
348 case 'I':
349 case 'J':
350 case 'K':
351 case 'L':
352 case 'M':
353 case 'N':
354 case 'O':
355 case 'P':
356 case 'Q':
357 case 'R':
358 case 'S':
359 case 'T':
360 case 'U':
361 case 'V':
362 case 'W':
363 case 'X':
364 case 'Y':
365 case 'Z':
366 {
367 bc_lex_number(l, c);
368 break;
369 }
370
371 case ';':
372 {
373 l->t = BC_LEX_SCOLON;
374 break;
375 }
376
377 case '<':
378 {
379 #if BC_ENABLE_EXTRA_MATH
380 c2 = l->buf[l->i];
381
382 // Check for shift.
383 if (c2 == '<')
384 {
385 l->i += 1;
386 bc_lex_assign(l, BC_LEX_OP_ASSIGN_LSHIFT, BC_LEX_OP_LSHIFT);
387 break;
388 }
389 #endif // BC_ENABLE_EXTRA_MATH
390 bc_lex_assign(l, BC_LEX_OP_REL_LE, BC_LEX_OP_REL_LT);
391 break;
392 }
393
394 case '=':
395 {
396 bc_lex_assign(l, BC_LEX_OP_REL_EQ, BC_LEX_OP_ASSIGN);
397 break;
398 }
399
400 case '>':
401 {
402 #if BC_ENABLE_EXTRA_MATH
403 c2 = l->buf[l->i];
404
405 // Check for shift.
406 if (c2 == '>')
407 {
408 l->i += 1;
409 bc_lex_assign(l, BC_LEX_OP_ASSIGN_RSHIFT, BC_LEX_OP_RSHIFT);
410 break;
411 }
412 #endif // BC_ENABLE_EXTRA_MATH
413 bc_lex_assign(l, BC_LEX_OP_REL_GE, BC_LEX_OP_REL_GT);
414 break;
415 }
416
417 case '[':
418 case ']':
419 {
420 l->t = (BcLexType) (c - '[' + BC_LEX_LBRACKET);
421 break;
422 }
423
424 case '\\':
425 {
426 // In bc, a backslash+newline is whitespace.
427 if (BC_NO_ERR(l->buf[l->i] == '\n'))
428 {
429 l->i += 1;
430 l->t = BC_LEX_WHITESPACE;
431 }
432 else bc_lex_invalidChar(l, c);
433 break;
434 }
435
436 case '^':
437 {
438 bc_lex_assign(l, BC_LEX_OP_ASSIGN_POWER, BC_LEX_OP_POWER);
439 break;
440 }
441
442 case 'a':
443 case 'b':
444 case 'c':
445 case 'd':
446 case 'e':
447 case 'f':
448 case 'g':
449 case 'h':
450 case 'i':
451 case 'j':
452 case 'k':
453 case 'l':
454 case 'm':
455 case 'n':
456 case 'o':
457 case 'p':
458 case 'q':
459 case 'r':
460 case 's':
461 case 't':
462 case 'u':
463 case 'v':
464 case 'w':
465 case 'x':
466 case 'y':
467 case 'z':
468 {
469 bc_lex_identifier(l);
470 break;
471 }
472
473 case '{':
474 case '}':
475 {
476 l->t = (BcLexType) (c - '{' + BC_LEX_LBRACE);
477 break;
478 }
479
480 case '|':
481 {
482 c2 = l->buf[l->i];
483
484 // Once again, boolean or is not allowed by POSIX.
485 if (BC_NO_ERR(c2 == '|'))
486 {
487 bc_lex_verr(l, BC_ERR_POSIX_BOOL, "||");
488
489 l->i += 1;
490 l->t = BC_LEX_OP_BOOL_OR;
491 }
492 else bc_lex_invalidChar(l, c);
493
494 break;
495 }
496
497 default:
498 {
499 bc_lex_invalidChar(l, c);
500 }
501 }
502 }
503 #endif // BC_ENABLED
504