Argyrios Kyrtzidis | 5404a15 | 2008-10-05 00:06:24 +0000 | [diff] [blame^] | 1 | //===--- ParseTentative.cpp - Ambiguity Resolution Parsing ----------------===// |
| 2 | // |
| 3 | // The LLVM Compiler Infrastructure |
| 4 | // |
| 5 | // This file is distributed under the University of Illinois Open Source |
| 6 | // License. See LICENSE.TXT for details. |
| 7 | // |
| 8 | //===----------------------------------------------------------------------===// |
| 9 | // |
| 10 | // This file implements the tentative parsing portions of the Parser |
| 11 | // interfaces, for ambiguity resolution. |
| 12 | // |
| 13 | //===----------------------------------------------------------------------===// |
| 14 | |
| 15 | #include "clang/Parse/Parser.h" |
| 16 | #include "clang/Basic/Diagnostic.h" |
| 17 | using namespace clang; |
| 18 | |
| 19 | /// isCXXDeclarationStatement - C++-specialized function that disambiguates |
| 20 | /// between a declaration or an expression statement, when parsing function |
| 21 | /// bodies. Returns true for declaration, false for expression. |
| 22 | /// |
| 23 | /// declaration-statement: |
| 24 | /// block-declaration |
| 25 | /// |
| 26 | /// block-declaration: |
| 27 | /// simple-declaration |
| 28 | /// asm-definition |
| 29 | /// namespace-alias-definition |
| 30 | /// using-declaration |
| 31 | /// using-directive |
| 32 | /// [C++0x] static_assert-declaration [TODO] |
| 33 | /// |
| 34 | /// asm-definition: |
| 35 | /// 'asm' '(' string-literal ')' ';' |
| 36 | /// |
| 37 | /// namespace-alias-definition: |
| 38 | /// 'namespace' identifier = qualified-namespace-specifier ';' |
| 39 | /// |
| 40 | /// using-declaration: |
| 41 | /// 'using' typename[opt] '::'[opt] nested-name-specifier |
| 42 | /// unqualified-id ';' |
| 43 | /// 'using' '::' unqualified-id ; |
| 44 | /// |
| 45 | /// using-directive: |
| 46 | /// 'using' 'namespace' '::'[opt] nested-name-specifier[opt] |
| 47 | /// namespace-name ';' |
| 48 | /// |
| 49 | /// [C++0x] static_assert-declaration: [TODO] |
| 50 | /// [C++0x] static_assert '(' constant-expression ',' string-literal ')' ';' |
| 51 | /// |
| 52 | bool Parser::isCXXDeclarationStatement() { |
| 53 | switch (Tok.getKind()) { |
| 54 | // asm-definition |
| 55 | case tok::kw_asm: |
| 56 | // namespace-alias-definition |
| 57 | case tok::kw_namespace: |
| 58 | // using-declaration |
| 59 | // using-directive |
| 60 | case tok::kw_using: |
| 61 | return true; |
| 62 | default: |
| 63 | // simple-declaration |
| 64 | return isCXXSimpleDeclaration(); |
| 65 | } |
| 66 | } |
| 67 | |
| 68 | /// isCXXSimpleDeclaration - C++-specialized function that disambiguates |
| 69 | /// between a simple-declaration or an expression-statement. |
| 70 | /// If during the disambiguation process a parsing error is encountered, |
| 71 | /// the function returns true to let the declaration parsing code handle it. |
| 72 | /// Returns false if the statement is disambiguated as expression. |
| 73 | /// |
| 74 | /// simple-declaration: |
| 75 | /// decl-specifier-seq init-declarator-list[opt] ';' |
| 76 | /// |
| 77 | bool Parser::isCXXSimpleDeclaration() { |
| 78 | // C++ 6.8p1: |
| 79 | // There is an ambiguity in the grammar involving expression-statements and |
| 80 | // declarations: An expression-statement with a function-style explicit type |
| 81 | // conversion (5.2.3) as its leftmost subexpression can be indistinguishable |
| 82 | // from a declaration where the first declarator starts with a '('. In those |
| 83 | // cases the statement is a declaration. [Note: To disambiguate, the whole |
| 84 | // statement might have to be examined to determine if it is an |
| 85 | // expression-statement or a declaration]. |
| 86 | |
| 87 | // C++ 6.8p3: |
| 88 | // The disambiguation is purely syntactic; that is, the meaning of the names |
| 89 | // occurring in such a statement, beyond whether they are type-names or not, |
| 90 | // is not generally used in or changed by the disambiguation. Class |
| 91 | // templates are instantiated as necessary to determine if a qualified name |
| 92 | // is a type-name. Disambiguation precedes parsing, and a statement |
| 93 | // disambiguated as a declaration may be an ill-formed declaration. |
| 94 | |
| 95 | // We don't have to parse all of the decl-specifier-seq part. There's only |
| 96 | // an ambiguity if the first decl-specifier is |
| 97 | // simple-type-specifier/typename-specifier followed by a '(', which may |
| 98 | // indicate a function-style cast expression. |
| 99 | // isCXXDeclarationSpecifier will return TPR_ambiguous only in such a case. |
| 100 | |
| 101 | TentativeParsingResult TPR = isCXXDeclarationSpecifier(); |
| 102 | if (TPR != TPR_ambiguous) |
| 103 | return TPR != TPR_false; // Returns true for TPR_true or TPR_error. |
| 104 | |
| 105 | // FIXME: Add statistics about the number of ambiguous statements encountered |
| 106 | // and how they were resolved (number of declarations+number of expressions). |
| 107 | |
| 108 | // Ok, we have a simple-type-specifier/typename-specifier followed by a '('. |
| 109 | // We need tentative parsing... |
| 110 | |
| 111 | TentativeParsingAction PA(*this); |
| 112 | |
| 113 | TPR = TryParseSimpleDeclaration(); |
| 114 | SourceLocation TentativeParseLoc = Tok.getLocation(); |
| 115 | |
| 116 | PA.Revert(); |
| 117 | |
| 118 | // In case of an error, let the declaration parsing code handle it. |
| 119 | if (TPR == TPR_error) |
| 120 | return true; |
| 121 | |
| 122 | // Declarations take precedence over expressions. |
| 123 | if (TPR == TPR_ambiguous) |
| 124 | TPR = TPR_true; |
| 125 | |
| 126 | assert(TPR == TPR_true || TPR == TPR_false); |
| 127 | if (TPR == TPR_true && Tok.isNot(tok::kw_void)) { |
| 128 | // We have a declaration that looks like a functional cast; there's a high |
| 129 | // chance that the author intended the statement to be an expression. |
| 130 | // Emit a warning. |
| 131 | Diag(Tok.getLocation(), diag::warn_statement_disambiguation, |
| 132 | "declaration", SourceRange(Tok.getLocation(), TentativeParseLoc)); |
| 133 | } else if (TPR == TPR_false && Tok.is(tok::kw_void)) { |
| 134 | // A functional cast to 'void' expression ? Warning.. |
| 135 | Diag(Tok.getLocation(), diag::warn_statement_disambiguation, |
| 136 | "expression", SourceRange(Tok.getLocation(), TentativeParseLoc)); |
| 137 | } |
| 138 | |
| 139 | return TPR == TPR_true; |
| 140 | } |
| 141 | |
| 142 | /// simple-declaration: |
| 143 | /// decl-specifier-seq init-declarator-list[opt] ';' |
| 144 | /// |
| 145 | Parser::TentativeParsingResult Parser::TryParseSimpleDeclaration() { |
| 146 | // We know that we have a simple-type-specifier/typename-specifier followed |
| 147 | // by a '('. |
| 148 | assert(isCXXDeclarationSpecifier() == TPR_ambiguous); |
| 149 | |
| 150 | if (Tok.is(tok::kw_typeof)) |
| 151 | TryParseTypeofSpecifier(); |
| 152 | else |
| 153 | ConsumeToken(); |
| 154 | |
| 155 | assert(Tok.is(tok::l_paren) && "Expected '('"); |
| 156 | |
| 157 | TentativeParsingResult TPR = TryParseInitDeclaratorList(); |
| 158 | if (TPR != TPR_ambiguous) |
| 159 | return TPR; |
| 160 | |
| 161 | if (Tok.isNot(tok::semi)) |
| 162 | return TPR_false; |
| 163 | |
| 164 | return TPR_ambiguous; |
| 165 | } |
| 166 | |
| 167 | /// init-declarator-list: |
| 168 | /// init-declarator |
| 169 | /// init-declarator-list ',' init-declarator |
| 170 | /// |
| 171 | /// init-declarator: |
| 172 | /// declarator initializer[opt] |
| 173 | /// |
| 174 | /// initializer: |
| 175 | /// '=' initializer-clause |
| 176 | /// '(' expression-list ')' |
| 177 | /// |
| 178 | /// initializer-clause: |
| 179 | /// assignment-expression |
| 180 | /// '{' initializer-list ','[opt] '}' |
| 181 | /// '{' '}' |
| 182 | /// |
| 183 | Parser::TentativeParsingResult Parser::TryParseInitDeclaratorList() { |
| 184 | // GCC only examines the first declarator for disambiguation: |
| 185 | // i.e: |
| 186 | // int(x), ++x; // GCC regards it as ill-formed declaration. |
| 187 | // |
| 188 | // Comeau and MSVC will regard the above statement as correct expression. |
| 189 | // Clang examines all of the declarators and also regards the above statement |
| 190 | // as correct expression. |
| 191 | |
| 192 | while (1) { |
| 193 | // declarator |
| 194 | TentativeParsingResult TPR = TryParseDeclarator(false/*mayBeAbstract*/); |
| 195 | if (TPR != TPR_ambiguous) |
| 196 | return TPR; |
| 197 | |
| 198 | // initializer[opt] |
| 199 | if (Tok.is(tok::l_paren)) { |
| 200 | // Parse through the parens. |
| 201 | ConsumeParen(); |
| 202 | if (!SkipUntil(tok::r_paren)) |
| 203 | return TPR_error; |
| 204 | } else if (Tok.is(tok::equal)) { |
| 205 | // MSVC won't examine the rest of declarators if '=' is encountered, it |
| 206 | // will conclude that it is a declaration. |
| 207 | // Comeau and Clang will examine the rest of declarators. |
| 208 | // Note that "int(x) = {0}, ++x;" will be interpreted as ill-formed |
| 209 | // expression. |
| 210 | // |
| 211 | // Parse through the initializer-clause. |
| 212 | SkipUntil(tok::comma, true/*StopAtSemi*/, true/*DontConsume*/); |
| 213 | } |
| 214 | |
| 215 | if (Tok.isNot(tok::comma)) |
| 216 | break; |
| 217 | ConsumeToken(); // the comma. |
| 218 | } |
| 219 | |
| 220 | return TPR_ambiguous; |
| 221 | } |
| 222 | |
| 223 | /// declarator: |
| 224 | /// direct-declarator |
| 225 | /// ptr-operator declarator |
| 226 | /// |
| 227 | /// direct-declarator: |
| 228 | /// declarator-id |
| 229 | /// direct-declarator '(' parameter-declaration-clause ')' |
| 230 | /// cv-qualifier-seq[opt] exception-specification[opt] |
| 231 | /// direct-declarator '[' constant-expression[opt] ']' |
| 232 | /// '(' declarator ')' |
| 233 | /// |
| 234 | /// abstract-declarator: |
| 235 | /// ptr-operator abstract-declarator[opt] |
| 236 | /// direct-abstract-declarator |
| 237 | /// |
| 238 | /// direct-abstract-declarator: |
| 239 | /// direct-abstract-declarator[opt] |
| 240 | /// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] |
| 241 | /// exception-specification[opt] |
| 242 | /// direct-abstract-declarator[opt] '[' constant-expression[opt] ']' |
| 243 | /// '(' abstract-declarator ')' |
| 244 | /// |
| 245 | /// ptr-operator: |
| 246 | /// '*' cv-qualifier-seq[opt] |
| 247 | /// '&' |
| 248 | /// [C++0x] '&&' [TODO] |
| 249 | /// '::'[opt] nested-name-specifier '*' cv-qualifier-seq[opt] [TODO] |
| 250 | /// |
| 251 | /// cv-qualifier-seq: |
| 252 | /// cv-qualifier cv-qualifier-seq[opt] |
| 253 | /// |
| 254 | /// cv-qualifier: |
| 255 | /// 'const' |
| 256 | /// 'volatile' |
| 257 | /// |
| 258 | /// declarator-id: |
| 259 | /// id-expression |
| 260 | /// |
| 261 | /// id-expression: |
| 262 | /// unqualified-id |
| 263 | /// qualified-id [TODO] |
| 264 | /// |
| 265 | /// unqualified-id: |
| 266 | /// identifier |
| 267 | /// operator-function-id [TODO] |
| 268 | /// conversion-function-id [TODO] |
| 269 | /// '~' class-name [TODO] |
| 270 | /// template-id [TODO] |
| 271 | /// |
| 272 | Parser::TentativeParsingResult Parser::TryParseDeclarator(bool mayBeAbstract) { |
| 273 | // declarator: |
| 274 | // direct-declarator |
| 275 | // ptr-operator declarator |
| 276 | |
| 277 | while (1) { |
| 278 | if (Tok.is(tok::star) || Tok.is(tok::amp)) { |
| 279 | // ptr-operator |
| 280 | ConsumeToken(); |
| 281 | while (Tok.is(tok::kw_const) || |
| 282 | Tok.is(tok::kw_volatile) || |
| 283 | Tok.is(tok::kw_restrict) ) |
| 284 | ConsumeToken(); |
| 285 | } else { |
| 286 | break; |
| 287 | } |
| 288 | } |
| 289 | |
| 290 | // direct-declarator: |
| 291 | // direct-abstract-declarator: |
| 292 | |
| 293 | if (Tok.is(tok::identifier)) { |
| 294 | // declarator-id |
| 295 | ConsumeToken(); |
| 296 | } else if (Tok.is(tok::l_paren)) { |
| 297 | if (mayBeAbstract && isCXXFunctionDeclarator()) { |
| 298 | // '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] |
| 299 | // exception-specification[opt] |
| 300 | TentativeParsingResult TPR = TryParseFunctionDeclarator(); |
| 301 | if (TPR != TPR_ambiguous) |
| 302 | return TPR; |
| 303 | } else { |
| 304 | // '(' declarator ')' |
| 305 | // '(' abstract-declarator ')' |
| 306 | ConsumeParen(); |
| 307 | TentativeParsingResult TPR = TryParseDeclarator(mayBeAbstract); |
| 308 | if (TPR != TPR_ambiguous) |
| 309 | return TPR; |
| 310 | if (Tok.isNot(tok::r_paren)) |
| 311 | return TPR_false; |
| 312 | ConsumeParen(); |
| 313 | } |
| 314 | } else if (!mayBeAbstract) { |
| 315 | return TPR_false; |
| 316 | } |
| 317 | |
| 318 | while (1) { |
| 319 | TentativeParsingResult TPR; |
| 320 | |
| 321 | if (Tok.is(tok::l_paren)) { |
| 322 | // direct-declarator '(' parameter-declaration-clause ')' |
| 323 | // cv-qualifier-seq[opt] exception-specification[opt] |
| 324 | if (!isCXXFunctionDeclarator()) |
| 325 | break; |
| 326 | TPR = TryParseFunctionDeclarator(); |
| 327 | } else if (Tok.is(tok::l_square)) { |
| 328 | // direct-declarator '[' constant-expression[opt] ']' |
| 329 | // direct-abstract-declarator[opt] '[' constant-expression[opt] ']' |
| 330 | TPR = TryParseBracketDeclarator(); |
| 331 | } else { |
| 332 | break; |
| 333 | } |
| 334 | |
| 335 | if (TPR != TPR_ambiguous) |
| 336 | return TPR; |
| 337 | } |
| 338 | |
| 339 | return TPR_ambiguous; |
| 340 | } |
| 341 | |
| 342 | /// isCXXDeclarationSpecifier - Returns TPR_true if it is a declaration |
| 343 | /// specifier, TPR_false if it is not, TPR_ambiguous if it could be either |
| 344 | /// a decl-specifier or a function-style cast, and TPR_error if a parsing |
| 345 | /// error was found and reported. |
| 346 | /// |
| 347 | /// decl-specifier: |
| 348 | /// storage-class-specifier |
| 349 | /// type-specifier |
| 350 | /// function-specifier |
| 351 | /// 'friend' |
| 352 | /// 'typedef' |
| 353 | /// [GNU] attributes declaration-specifiers[opt] |
| 354 | /// |
| 355 | /// storage-class-specifier: |
| 356 | /// 'register' |
| 357 | /// 'static' |
| 358 | /// 'extern' |
| 359 | /// 'mutable' |
| 360 | /// 'auto' |
| 361 | /// [GNU] '__thread' |
| 362 | /// |
| 363 | /// function-specifier: |
| 364 | /// 'inline' |
| 365 | /// 'virtual' |
| 366 | /// 'explicit' |
| 367 | /// |
| 368 | /// typedef-name: |
| 369 | /// identifier |
| 370 | /// |
| 371 | /// type-specifier: |
| 372 | /// simple-type-specifier |
| 373 | /// class-specifier |
| 374 | /// enum-specifier |
| 375 | /// elaborated-type-specifier |
| 376 | /// typename-specifier [TODO] |
| 377 | /// cv-qualifier |
| 378 | /// |
| 379 | /// simple-type-specifier: |
| 380 | /// '::'[opt] nested-name-specifier[opt] type-name [TODO] |
| 381 | /// '::'[opt] nested-name-specifier 'template' |
| 382 | /// simple-template-id [TODO] |
| 383 | /// 'char' |
| 384 | /// 'wchar_t' |
| 385 | /// 'bool' |
| 386 | /// 'short' |
| 387 | /// 'int' |
| 388 | /// 'long' |
| 389 | /// 'signed' |
| 390 | /// 'unsigned' |
| 391 | /// 'float' |
| 392 | /// 'double' |
| 393 | /// 'void' |
| 394 | /// [GNU] typeof-specifier |
| 395 | /// [GNU] '_Complex' |
| 396 | /// [C++0x] 'auto' [TODO] |
| 397 | /// |
| 398 | /// type-name: |
| 399 | /// class-name |
| 400 | /// enum-name |
| 401 | /// typedef-name |
| 402 | /// |
| 403 | /// elaborated-type-specifier: |
| 404 | /// class-key '::'[opt] nested-name-specifier[opt] identifier |
| 405 | /// class-key '::'[opt] nested-name-specifier[opt] 'template'[opt] |
| 406 | /// simple-template-id |
| 407 | /// 'enum' '::'[opt] nested-name-specifier[opt] identifier |
| 408 | /// |
| 409 | /// enum-name: |
| 410 | /// identifier |
| 411 | /// |
| 412 | /// enum-specifier: |
| 413 | /// 'enum' identifier[opt] '{' enumerator-list[opt] '}' |
| 414 | /// 'enum' identifier[opt] '{' enumerator-list ',' '}' |
| 415 | /// |
| 416 | /// class-specifier: |
| 417 | /// class-head '{' member-specification[opt] '}' |
| 418 | /// |
| 419 | /// class-head: |
| 420 | /// class-key identifier[opt] base-clause[opt] |
| 421 | /// class-key nested-name-specifier identifier base-clause[opt] |
| 422 | /// class-key nested-name-specifier[opt] simple-template-id |
| 423 | /// base-clause[opt] |
| 424 | /// |
| 425 | /// class-key: |
| 426 | /// 'class' |
| 427 | /// 'struct' |
| 428 | /// 'union' |
| 429 | /// |
| 430 | /// cv-qualifier: |
| 431 | /// 'const' |
| 432 | /// 'volatile' |
| 433 | /// [GNU] restrict |
| 434 | /// |
| 435 | Parser::TentativeParsingResult Parser::isCXXDeclarationSpecifier() { |
| 436 | switch (Tok.getKind()) { |
| 437 | // decl-specifier: |
| 438 | // storage-class-specifier |
| 439 | // type-specifier |
| 440 | // function-specifier |
| 441 | // 'friend' |
| 442 | // 'typedef' |
| 443 | |
| 444 | case tok::kw_friend: |
| 445 | case tok::kw_typedef: |
| 446 | // storage-class-specifier |
| 447 | case tok::kw_register: |
| 448 | case tok::kw_static: |
| 449 | case tok::kw_extern: |
| 450 | case tok::kw_mutable: |
| 451 | case tok::kw_auto: |
| 452 | case tok::kw___thread: |
| 453 | // function-specifier |
| 454 | case tok::kw_inline: |
| 455 | case tok::kw_virtual: |
| 456 | case tok::kw_explicit: |
| 457 | |
| 458 | // type-specifier: |
| 459 | // simple-type-specifier |
| 460 | // class-specifier |
| 461 | // enum-specifier |
| 462 | // elaborated-type-specifier |
| 463 | // typename-specifier |
| 464 | // cv-qualifier |
| 465 | |
| 466 | // class-specifier |
| 467 | // elaborated-type-specifier |
| 468 | case tok::kw_class: |
| 469 | case tok::kw_struct: |
| 470 | case tok::kw_union: |
| 471 | // enum-specifier |
| 472 | case tok::kw_enum: |
| 473 | // cv-qualifier |
| 474 | case tok::kw_const: |
| 475 | case tok::kw_volatile: |
| 476 | |
| 477 | // GNU |
| 478 | case tok::kw_restrict: |
| 479 | case tok::kw__Complex: |
| 480 | case tok::kw___attribute: |
| 481 | return TPR_true; |
| 482 | |
| 483 | // The ambiguity resides in a simple-type-specifier/typename-specifier |
| 484 | // followed by a '('. The '(' could either be the start of: |
| 485 | // |
| 486 | // direct-declarator: |
| 487 | // '(' declarator ')' |
| 488 | // |
| 489 | // direct-abstract-declarator: |
| 490 | // '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] |
| 491 | // exception-specification[opt] |
| 492 | // '(' abstract-declarator ')' |
| 493 | // |
| 494 | // or part of a function-style cast expression: |
| 495 | // |
| 496 | // simple-type-specifier '(' expression-list[opt] ')' |
| 497 | // |
| 498 | |
| 499 | // simple-type-specifier: |
| 500 | |
| 501 | case tok::identifier: |
| 502 | if (!Actions.isTypeName(*Tok.getIdentifierInfo(), CurScope)) |
| 503 | return TPR_false; |
| 504 | // FALL THROUGH. |
| 505 | |
| 506 | case tok::kw_char: |
| 507 | case tok::kw_wchar_t: |
| 508 | case tok::kw_bool: |
| 509 | case tok::kw_short: |
| 510 | case tok::kw_int: |
| 511 | case tok::kw_long: |
| 512 | case tok::kw_signed: |
| 513 | case tok::kw_unsigned: |
| 514 | case tok::kw_float: |
| 515 | case tok::kw_double: |
| 516 | case tok::kw_void: |
| 517 | if (NextToken().is(tok::l_paren)) |
| 518 | return TPR_ambiguous; |
| 519 | |
| 520 | return TPR_true; |
| 521 | |
| 522 | // GNU typeof support. |
| 523 | case tok::kw_typeof: { |
| 524 | if (NextToken().isNot(tok::l_paren)) |
| 525 | return TPR_true; |
| 526 | |
| 527 | TentativeParsingAction PA(*this); |
| 528 | |
| 529 | TentativeParsingResult TPR = TryParseTypeofSpecifier(); |
| 530 | bool isFollowedByParen = Tok.is(tok::l_paren); |
| 531 | |
| 532 | PA.Revert(); |
| 533 | |
| 534 | if (TPR == TPR_error) |
| 535 | return TPR_error; |
| 536 | |
| 537 | if (isFollowedByParen) |
| 538 | return TPR_ambiguous; |
| 539 | |
| 540 | return TPR_true; |
| 541 | } |
| 542 | |
| 543 | default: |
| 544 | return TPR_false; |
| 545 | } |
| 546 | } |
| 547 | |
| 548 | /// [GNU] typeof-specifier: |
| 549 | /// 'typeof' '(' expressions ')' |
| 550 | /// 'typeof' '(' type-name ')' |
| 551 | /// |
| 552 | Parser::TentativeParsingResult Parser::TryParseTypeofSpecifier() { |
| 553 | assert(Tok.is(tok::kw_typeof) && "Expected 'typeof'!"); |
| 554 | ConsumeToken(); |
| 555 | |
| 556 | assert(Tok.is(tok::l_paren) && "Expected '('"); |
| 557 | // Parse through the parens after 'typeof'. |
| 558 | ConsumeParen(); |
| 559 | if (!SkipUntil(tok::r_paren)) |
| 560 | return TPR_error; |
| 561 | |
| 562 | return TPR_ambiguous; |
| 563 | } |
| 564 | |
| 565 | Parser::TentativeParsingResult Parser::TryParseDeclarationSpecifier() { |
| 566 | TentativeParsingResult TPR = isCXXDeclarationSpecifier(); |
| 567 | if (TPR != TPR_ambiguous) |
| 568 | return TPR; |
| 569 | |
| 570 | if (Tok.is(tok::kw_typeof)) |
| 571 | TryParseTypeofSpecifier(); |
| 572 | else |
| 573 | ConsumeToken(); |
| 574 | |
| 575 | assert(Tok.is(tok::l_paren) && "Expected '('!"); |
| 576 | return TPR_ambiguous; |
| 577 | } |
| 578 | |
| 579 | /// isCXXFunctionDeclarator - Disambiguates between a function declarator or |
| 580 | /// a constructor-style initializer, when parsing declaration statements. |
| 581 | /// Returns true for function declarator and false for constructor-style |
| 582 | /// initializer. |
| 583 | /// If during the disambiguation process a parsing error is encountered, |
| 584 | /// the function returns true to let the declaration parsing code handle it. |
| 585 | /// |
| 586 | /// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] |
| 587 | /// exception-specification[opt] |
| 588 | /// |
| 589 | bool Parser::isCXXFunctionDeclarator() { |
| 590 | TentativeParsingAction PA(*this); |
| 591 | |
| 592 | ConsumeParen(); |
| 593 | TentativeParsingResult TPR = TryParseParameterDeclarationClause(); |
| 594 | if (TPR == TPR_ambiguous && Tok.isNot(tok::r_paren)) |
| 595 | TPR = TPR_false; |
| 596 | |
| 597 | PA.Revert(); |
| 598 | |
| 599 | // In case of an error, let the declaration parsing code handle it. |
| 600 | if (TPR == TPR_error) |
| 601 | return true; |
| 602 | |
| 603 | // Function declarator has precedence over constructor-style initializer. |
| 604 | if (TPR == TPR_ambiguous) |
| 605 | return TPR_true; |
| 606 | return TPR == TPR_true; |
| 607 | } |
| 608 | |
| 609 | /// parameter-declaration-clause: |
| 610 | /// parameter-declaration-list[opt] '...'[opt] |
| 611 | /// parameter-declaration-list ',' '...' |
| 612 | /// |
| 613 | /// parameter-declaration-list: |
| 614 | /// parameter-declaration |
| 615 | /// parameter-declaration-list ',' parameter-declaration |
| 616 | /// |
| 617 | /// parameter-declaration: |
| 618 | /// decl-specifier-seq declarator |
| 619 | /// decl-specifier-seq declarator '=' assignment-expression |
| 620 | /// decl-specifier-seq abstract-declarator[opt] |
| 621 | /// decl-specifier-seq abstract-declarator[opt] '=' assignment-expression |
| 622 | /// |
| 623 | Parser::TentativeParsingResult Parser::TryParseParameterDeclarationClause() { |
| 624 | |
| 625 | if (Tok.is(tok::r_paren)) |
| 626 | return TPR_true; |
| 627 | |
| 628 | // parameter-declaration-list[opt] '...'[opt] |
| 629 | // parameter-declaration-list ',' '...' |
| 630 | // |
| 631 | // parameter-declaration-list: |
| 632 | // parameter-declaration |
| 633 | // parameter-declaration-list ',' parameter-declaration |
| 634 | // |
| 635 | while (1) { |
| 636 | // '...'[opt] |
| 637 | if (Tok.is(tok::ellipsis)) { |
| 638 | ConsumeToken(); |
| 639 | return TPR_true; // '...' is a sign of a function declarator. |
| 640 | } |
| 641 | |
| 642 | // decl-specifier-seq |
| 643 | TentativeParsingResult TPR = TryParseDeclarationSpecifier(); |
| 644 | if (TPR != TPR_ambiguous) |
| 645 | return TPR; |
| 646 | |
| 647 | // declarator |
| 648 | // abstract-declarator[opt] |
| 649 | TPR = TryParseDeclarator(true/*mayBeAbstract*/); |
| 650 | if (TPR != TPR_ambiguous) |
| 651 | return TPR; |
| 652 | |
| 653 | if (Tok.is(tok::equal)) { |
| 654 | // '=' assignment-expression |
| 655 | // Parse through assignment-expression. |
| 656 | tok::TokenKind StopToks[3] ={ tok::comma, tok::ellipsis, tok::r_paren }; |
| 657 | if (!SkipUntil(StopToks, 3, true/*StopAtSemi*/, true/*DontConsume*/)) |
| 658 | return TPR_error; |
| 659 | } |
| 660 | |
| 661 | if (Tok.is(tok::ellipsis)) { |
| 662 | ConsumeToken(); |
| 663 | return TPR_true; // '...' is a sign of a function declarator. |
| 664 | } |
| 665 | |
| 666 | if (Tok.isNot(tok::comma)) |
| 667 | break; |
| 668 | ConsumeToken(); // the comma. |
| 669 | } |
| 670 | |
| 671 | return TPR_ambiguous; |
| 672 | } |
| 673 | |
| 674 | /// TryParseFunctionDeclarator - We previously determined (using |
| 675 | /// isCXXFunctionDeclarator) that we are at a function declarator. Now parse |
| 676 | /// through it. |
| 677 | /// |
| 678 | /// '(' parameter-declaration-clause ')' cv-qualifier-seq[opt] |
| 679 | /// exception-specification[opt] |
| 680 | /// |
| 681 | /// exception-specification: |
| 682 | /// 'throw' '(' type-id-list[opt] ')' |
| 683 | /// |
| 684 | Parser::TentativeParsingResult Parser::TryParseFunctionDeclarator() { |
| 685 | assert(Tok.is(tok::l_paren)); |
| 686 | // Parse through the parens. |
| 687 | ConsumeParen(); |
| 688 | if (!SkipUntil(tok::r_paren)) |
| 689 | return TPR_error; |
| 690 | |
| 691 | // cv-qualifier-seq |
| 692 | while (Tok.is(tok::kw_const) || |
| 693 | Tok.is(tok::kw_volatile) || |
| 694 | Tok.is(tok::kw_restrict) ) |
| 695 | ConsumeToken(); |
| 696 | |
| 697 | // exception-specification |
| 698 | if (Tok.is(tok::kw_throw)) { |
| 699 | ConsumeToken(); |
| 700 | if (Tok.isNot(tok::l_paren)) |
| 701 | return TPR_error; |
| 702 | |
| 703 | // Parse through the parens after 'throw'. |
| 704 | ConsumeParen(); |
| 705 | if (!SkipUntil(tok::r_paren)) |
| 706 | return TPR_error; |
| 707 | } |
| 708 | |
| 709 | return TPR_ambiguous; |
| 710 | } |
| 711 | |
| 712 | /// '[' constant-expression[opt] ']' |
| 713 | /// |
| 714 | Parser::TentativeParsingResult Parser::TryParseBracketDeclarator() { |
| 715 | ConsumeBracket(); |
| 716 | if (!SkipUntil(tok::r_square)) |
| 717 | return TPR_error; |
| 718 | |
| 719 | return TPR_ambiguous; |
| 720 | } |