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annotate lwbasic/parser.c @ 43:18b49cf10ae9
Added an instruction reduction immediately after instruction parsing to minimize memory footprint and expression complexity
| author | lost@l-w.ca |
|---|---|
| date | Mon, 04 Apr 2011 17:55:08 -0600 |
| parents | 5325b640424d |
| children |
| rev | line source |
|---|---|
| 25 | 1 /* |
| 2 compiler.c | |
| 3 | |
| 4 Copyright © 2011 William Astle | |
| 5 | |
| 6 This file is part of LWTOOLS. | |
| 7 | |
| 8 LWTOOLS is free software: you can redistribute it and/or modify it under the | |
| 9 terms of the GNU General Public License as published by the Free Software | |
| 10 Foundation, either version 3 of the License, or (at your option) any later | |
| 11 version. | |
| 12 | |
| 13 This program is distributed in the hope that it will be useful, but WITHOUT | |
| 14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
| 16 more details. | |
| 17 | |
| 18 You should have received a copy of the GNU General Public License along with | |
| 19 this program. If not, see <http://www.gnu.org/licenses/>. | |
| 20 */ | |
| 21 | |
| 22 /* | |
| 23 This is the actual compiler bit; it drives the parser and code generation | |
| 24 */ | |
| 25 | |
| 26 #include <stdio.h> | |
| 27 | |
|
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28 #include <lw_alloc.h> |
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29 #include <lw_string.h> |
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30 |
| 25 | 31 #include "lwbasic.h" |
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32 #include "symtab.h" |
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33 |
| 34 | 34 static void expect(cstate *state, int tt) |
| 35 { | |
| 36 if (state -> lexer_token != tt) | |
| 37 lwb_error("Expecting %s, got %s\n", lexer_token_name(tt), lexer_return_token(state)); | |
| 38 lexer(state); | |
| 39 } | |
| 40 | |
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41 |
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42 /* size of a type */ |
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43 static int sizeof_type(int type) |
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44 { |
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45 /* everything is an "int" right now; 2 bytes */ |
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46 return 2; |
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47 } |
| 25 | 48 |
| 49 /* parse a type; the next token will be acquired as a result */ | |
| 50 /* the token advancement is to provide consistency */ | |
| 51 static int parse_type(cstate *state) | |
| 52 { | |
| 53 int pt = -1; | |
| 54 | |
| 55 switch (state -> lexer_token) | |
| 56 { | |
| 57 case token_kw_integer: | |
| 58 pt = 1; | |
| 59 break; | |
| 60 | |
| 61 default: | |
| 62 lwb_error("Invalid type specification"); | |
| 63 } | |
| 64 lexer(state); | |
| 65 /* look for "unsigned" modifier for integer types */ | |
| 66 return pt; | |
| 67 } | |
| 68 | |
| 36 | 69 static void parse_expr(cstate *state, int prec); |
| 70 static void parse_term(cstate *state); | |
| 35 | 71 static int parse_expression(cstate *state) |
| 72 { | |
| 73 state -> expression = 1; | |
| 74 | |
| 36 | 75 parse_expr(state, 0); |
| 76 | |
| 35 | 77 state -> expression = 0; |
| 78 return 1; | |
| 79 } | |
| 80 | |
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81 static void parse_decls(cstate *state) |
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82 { |
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83 /* declarations */ |
| 33 | 84 /* the first thing that doesn't look like a declaration is assumed */ |
| 85 /* to be a statement and will trigger a bailout */ | |
| 86 int vt; | |
| 87 char *vn; | |
| 88 symtab_entry_t *se; | |
| 89 | |
| 90 for (;;) | |
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91 { |
| 33 | 92 switch (state -> lexer_token) |
| 93 { | |
| 94 /* DIM keyword */ | |
| 95 case token_kw_dim: | |
| 96 lexer(state); | |
| 97 if (state -> lexer_token != token_identifier) | |
| 98 { | |
| 99 lwb_error("Expecting identifier, got %s\n", lexer_return_token(state)); | |
| 100 } | |
| 101 vn = lw_strdup(state -> lexer_token_string); | |
| 102 lexer(state); | |
| 103 if (state -> lexer_token != token_kw_as) | |
| 104 { | |
| 105 lwb_error("Expecting AS, got %s\n", lexer_return_token(state)); | |
| 106 } | |
| 107 lexer(state); | |
| 108 vt = parse_type(state); | |
| 109 | |
| 110 se = symtab_find(state -> local_syms, vn); | |
| 111 if (se) | |
| 112 { | |
| 113 lwb_error("Multiply defined local variable %s", vn); | |
| 114 } | |
| 115 state -> framesize += sizeof_type(vt); | |
| 116 symtab_register(state -> local_syms, vn, -(state -> framesize), symtype_var, NULL); | |
| 117 | |
| 118 lw_free(vn); | |
| 119 break; | |
| 34 | 120 |
| 121 /* blank lines allowed */ | |
| 122 case token_eol: | |
| 123 break; | |
| 124 | |
| 33 | 125 default: |
| 126 return; | |
| 127 } | |
| 128 if (state -> lexer_token != token_eol) | |
| 34 | 129 lwb_error("Expecting end of line; got %s\n", lexer_return_token(state)); |
| 130 lexer(state); | |
| 131 } | |
| 132 } | |
| 133 | |
| 134 static void parse_statements(cstate *state) | |
| 135 { | |
| 136 symtab_entry_t *se; | |
| 35 | 137 int et; |
| 34 | 138 |
| 139 for (;;) | |
| 140 { | |
| 141 switch (state -> lexer_token) | |
| 142 { | |
| 143 /* blank lines allowed */ | |
| 144 case token_eol: | |
| 145 break; | |
| 146 | |
| 147 /* variable assignment */ | |
| 148 case token_identifier: | |
| 149 se = symtab_find(state -> local_syms, state -> lexer_token_string); | |
| 150 if (!se) | |
| 151 { | |
| 152 se = symtab_find(state -> global_syms, state -> lexer_token_string); | |
| 153 } | |
| 154 if (!se) | |
| 155 lwb_error("Unknown variable %s\n", state -> lexer_token_string); | |
| 156 lexer(state); | |
| 35 | 157 /* ensure the first token of the expression will be parsed correctly */ |
| 158 state -> expression = 1; | |
| 34 | 159 expect(state, token_op_assignment); |
| 160 | |
| 161 /* parse the expression */ | |
| 35 | 162 et = parse_expression(state); |
| 163 | |
| 164 /* check type compatibility */ | |
| 34 | 165 |
| 166 /* actually do the assignment */ | |
| 167 | |
| 168 break; | |
| 169 | |
| 170 /* anything we don't recognize as a statement token breaks out */ | |
| 171 default: | |
| 172 return; | |
| 173 } | |
| 174 if (state -> lexer_token != token_eol) | |
| 175 lwb_error("Expecting end of line; got %s\n", lexer_return_token(state)); | |
| 33 | 176 lexer(state); |
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177 } |
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178 } |
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179 |
| 25 | 180 |
| 181 /* issub means RETURNS is not allowed; !issub means RETURNS is required */ | |
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182 |
| 25 | 183 static void parse_subfunc(cstate *state, int issub) |
| 184 { | |
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185 int pt, rt; |
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186 char *subname, *pn; |
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187 int vis = 0; |
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188 symtab_entry_t *se; |
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189 int paramsize = 0; |
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190 |
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191 state -> local_syms = symtab_init(); |
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192 state -> framesize = 0; |
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193 |
| 25 | 194 lexer(state); |
| 195 if (state -> lexer_token != token_identifier) | |
| 196 { | |
| 197 lwb_error("Invalid sub name '%s'", state -> lexer_token_string); | |
| 198 } | |
| 199 | |
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200 subname = lw_strdup(state -> lexer_token_string); |
| 25 | 201 |
| 202 lexer(state); | |
| 203 if (state -> lexer_token == token_kw_public || state -> lexer_token == token_kw_private) | |
| 204 { | |
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205 if (state -> lexer_token == token_kw_public) |
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206 vis = 1; |
| 25 | 207 lexer(state); |
| 208 } | |
| 209 | |
| 210 /* ignore the "PARAMS" keyword if present */ | |
| 211 if (state -> lexer_token == token_kw_params) | |
| 212 lexer(state); | |
| 213 | |
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214 if (state -> lexer_token == token_eol || state -> lexer_token == token_kw_returns) |
| 25 | 215 goto noparms; |
| 216 | |
| 217 paramagain: | |
| 218 if (state -> lexer_token != token_identifier) | |
| 219 { | |
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220 lwb_error("Parameter name expected, got %s\n", lexer_return_token(state)); |
| 25 | 221 } |
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222 pn = lw_strdup(state -> lexer_token_string); |
| 25 | 223 lexer(state); |
| 224 | |
| 225 if (state -> lexer_token != token_kw_as) | |
| 226 lwb_error("Expecting AS\n"); | |
| 227 lexer(state); | |
| 228 | |
| 229 pt = parse_type(state); | |
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230 |
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231 se = symtab_find(state -> local_syms, pn); |
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232 if (se) |
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233 { |
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234 lwb_error("Duplicate parameter name %s\n", pn); |
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235 } |
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236 symtab_register(state -> local_syms, pn, paramsize, symtype_param, NULL); |
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237 paramsize += sizeof_type(pt); |
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238 lw_free(pn); |
| 25 | 239 |
| 240 if (state -> lexer_token == token_char && state -> lexer_token_string[0] == ',') | |
| 241 { | |
| 242 lexer(state); | |
| 243 goto paramagain; | |
| 244 } | |
| 245 | |
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246 noparms: |
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247 rt = -1; |
| 25 | 248 if (!issub) |
| 249 { | |
| 250 if (state -> lexer_token != token_kw_returns) | |
| 251 { | |
| 252 lwb_error("FUNCTION must have RETURNS\n"); | |
| 253 } | |
| 254 lexer(state); | |
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255 /* if (state -> lexer_token == token_identifier) |
| 25 | 256 { |
| 257 printf("Return value named: %s\n", state -> lexer_token_string); | |
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258 |
| 25 | 259 lexer(state); |
| 260 if (state -> lexer_token != token_kw_as) | |
| 261 lwb_error("Execting AS after RETURNS"); | |
| 262 lexer(state); | |
| 263 } | |
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264 */ |
| 25 | 265 rt = parse_type(state); |
| 266 } | |
| 267 else | |
| 268 { | |
| 269 if (state -> lexer_token == token_kw_returns) | |
| 270 { | |
| 271 lwb_error("SUB cannot specify RETURNS\n"); | |
| 272 } | |
| 273 } | |
| 274 | |
| 275 | |
| 276 if (state -> lexer_token != token_eol) | |
| 277 { | |
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278 lwb_error("EOL expected; found %s\n", lexer_return_token(state)); |
| 25 | 279 } |
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280 |
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281 |
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282 se = symtab_find(state -> global_syms, subname); |
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283 if (se) |
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284 { |
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285 lwb_error("Multiply defined symbol %s\n", subname); |
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286 } |
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287 |
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288 symtab_register(state -> global_syms, subname, -1, issub ? symtype_sub : symtype_func, NULL); |
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289 |
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290 state -> currentsub = subname; |
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291 state -> returntype = rt; |
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292 /* consume EOL */ |
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293 lexer(state); |
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294 |
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295 /* variable declarations */ |
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296 parse_decls(state); |
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297 |
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298 /* output function/sub prolog */ |
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299 emit_prolog(state, vis); |
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300 |
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301 /* parse statement block */ |
| 34 | 302 parse_statements(state); |
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303 |
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304 if (issub) |
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305 { |
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306 if (state -> lexer_token != token_kw_endsub) |
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307 { |
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308 lwb_error("Expecting ENDSUB, got %s\n", lexer_return_token(state)); |
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309 } |
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310 } |
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311 else |
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312 { |
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313 if (state -> lexer_token != token_kw_endfunction) |
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314 { |
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315 lwb_error("Expecting ENDFUNCTION, got %s\n", lexer_return_token(state)); |
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316 } |
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317 } |
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318 /* output function/sub epilog */ |
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319 emit_epilog(state); |
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320 |
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321 lw_free(state -> currentsub); |
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322 state -> currentsub = NULL; |
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323 symtab_destroy(state -> local_syms); |
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324 state -> local_syms = NULL; |
| 25 | 325 } |
| 326 | |
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327 void parser(cstate *state) |
| 25 | 328 { |
| 329 state -> lexer_curchar = -1; | |
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330 state -> global_syms = symtab_init(); |
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331 |
| 25 | 332 /* now look for a global declaration */ |
| 333 for (;;) | |
| 334 { | |
| 335 state -> parser_state = parser_state_global; | |
| 336 lexer(state); | |
| 337 switch (state -> lexer_token) | |
| 338 { | |
| 339 case token_kw_function: | |
| 340 printf("Function\n"); | |
| 341 parse_subfunc(state, 0); | |
| 342 break; | |
| 343 | |
| 344 case token_kw_sub: | |
| 345 printf("Sub\n"); | |
| 346 parse_subfunc(state, 1); | |
| 347 break; | |
| 348 | |
| 349 /* blank lines are allowed */ | |
| 350 case token_eol: | |
| 351 continue; | |
| 352 | |
| 353 /* EOF is allowed - end of parsing */ | |
| 354 case token_eof: | |
| 355 return; | |
| 356 | |
| 357 default: | |
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358 lwb_error("Invalid token '%s' in global state\n", lexer_return_token(state)); |
| 25 | 359 } |
| 360 } | |
| 361 } | |
| 36 | 362 |
| 363 static void parse_expr(cstate *state, int prec) | |
| 364 { | |
| 365 static const struct operinfo { | |
| 366 int opernum; | |
| 367 int operprec; | |
| 368 } operators[] = | |
| 369 { | |
| 370 { token_op_plus, 100 }, | |
| 371 { token_op_minus, 100 }, | |
| 372 { token_op_times, 150 }, | |
| 373 { token_op_divide, 150 }, | |
| 374 { token_op_modulus, 150 }, | |
| 375 { token_op_and, 25 }, | |
| 376 { token_op_or, 20 }, | |
| 377 { token_op_xor, 20 }, | |
| 378 { token_op_band, 50 }, | |
| 379 { token_op_bor, 45 }, | |
| 380 { token_op_bxor, 45 }, | |
| 381 { -1, -1 } | |
| 382 }; | |
| 383 int opern; | |
| 384 | |
| 385 parse_term(state); | |
| 386 | |
| 387 eval_next: | |
| 388 for (opern = 0; operators[opern].opernum != -1; opern++) | |
| 389 { | |
| 390 if (operators[opern].opernum == state -> lexer_token) | |
| 391 break; | |
| 392 } | |
| 393 if (operators[opern].opernum == -1) | |
| 394 return; | |
| 395 | |
| 396 if (operators[opern].operprec <= prec) | |
| 397 return; | |
| 398 | |
| 399 lexer(state); | |
| 400 | |
| 401 parse_expr(state, operators[opern].operprec); | |
| 402 | |
| 403 /* push operator */ | |
| 404 | |
| 405 goto eval_next; | |
| 406 } | |
| 407 | |
| 408 static void parse_term(cstate *state) | |
| 409 { | |
| 410 eval_next: | |
| 411 /* parens */ | |
| 412 if (state -> lexer_token == token_op_oparen) | |
| 413 { | |
| 414 lexer(state); | |
| 415 parse_expr(state, 0); | |
| 416 expect(state, token_op_cparen); | |
| 417 return; | |
| 418 } | |
| 419 | |
| 420 /* unary plus; ignore it */ | |
| 421 if (state -> lexer_token == token_op_plus) | |
| 422 { | |
| 423 lexer(state); | |
| 424 goto eval_next; | |
| 425 } | |
| 426 | |
| 427 /* unary minus, precision 200 */ | |
| 428 if (state -> lexer_token == token_op_minus) | |
| 429 { | |
| 430 lexer(state); | |
| 431 parse_expr(state, 200); | |
| 432 | |
| 433 /* push unary negation */ | |
| 434 } | |
| 435 | |
| 436 /* BNOT, NOT */ | |
| 437 if (state -> lexer_token == token_op_not || state -> lexer_token == token_op_bnot) | |
| 438 { | |
| 439 lexer(state); | |
| 440 parse_expr(state, 200); | |
| 441 | |
| 442 /* push unary operator */ | |
| 443 } | |
| 444 | |
| 445 /* integer */ | |
| 446 if (state -> lexer_token == token_int) | |
| 447 { | |
| 448 } | |
| 449 | |
| 450 /* unsigned integer */ | |
| 451 if (state -> lexer_token == token_uint) | |
| 452 { | |
| 453 } | |
| 454 | |
| 455 /* variable or function call */ | |
| 456 if (state -> lexer_token == token_identifier) | |
| 457 { | |
| 458 lexer(state); | |
| 459 if (state -> lexer_token == token_op_oparen) | |
| 460 { | |
| 461 /* function call */ | |
| 462 return; | |
| 463 } | |
| 464 /* variable */ | |
| 465 return; | |
| 466 } | |
| 467 | |
| 468 lwb_error("Invalid input in expression; got %s\n", lexer_return_token(state)); | |
| 469 } |