ParseInit.cpp revision 226633
1//===--- ParseInit.cpp - Initializer 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 initializer parsing as specified by C99 6.7.8. 11// 12//===----------------------------------------------------------------------===// 13 14#include "clang/Parse/Parser.h" 15#include "clang/Parse/ParseDiagnostic.h" 16#include "RAIIObjectsForParser.h" 17#include "clang/Sema/Designator.h" 18#include "clang/Sema/Scope.h" 19#include "llvm/ADT/SmallString.h" 20#include "llvm/Support/raw_ostream.h" 21using namespace clang; 22 23 24/// MayBeDesignationStart - Return true if this token might be the start of a 25/// designator. If we can tell it is impossible that it is a designator, return 26/// false. 27static bool MayBeDesignationStart(tok::TokenKind K, Preprocessor &PP) { 28 switch (K) { 29 default: return false; 30 case tok::period: // designator: '.' identifier 31 case tok::l_square: // designator: array-designator 32 return true; 33 case tok::identifier: // designation: identifier ':' 34 return PP.LookAhead(0).is(tok::colon); 35 } 36} 37 38static void CheckArrayDesignatorSyntax(Parser &P, SourceLocation Loc, 39 Designation &Desig) { 40 // If we have exactly one array designator, this used the GNU 41 // 'designation: array-designator' extension, otherwise there should be no 42 // designators at all! 43 if (Desig.getNumDesignators() == 1 && 44 (Desig.getDesignator(0).isArrayDesignator() || 45 Desig.getDesignator(0).isArrayRangeDesignator())) 46 P.Diag(Loc, diag::ext_gnu_missing_equal_designator); 47 else if (Desig.getNumDesignators() > 0) 48 P.Diag(Loc, diag::err_expected_equal_designator); 49} 50 51/// ParseInitializerWithPotentialDesignator - Parse the 'initializer' production 52/// checking to see if the token stream starts with a designator. 53/// 54/// designation: 55/// designator-list '=' 56/// [GNU] array-designator 57/// [GNU] identifier ':' 58/// 59/// designator-list: 60/// designator 61/// designator-list designator 62/// 63/// designator: 64/// array-designator 65/// '.' identifier 66/// 67/// array-designator: 68/// '[' constant-expression ']' 69/// [GNU] '[' constant-expression '...' constant-expression ']' 70/// 71/// NOTE: [OBC] allows '[ objc-receiver objc-message-args ]' as an 72/// initializer (because it is an expression). We need to consider this case 73/// when parsing array designators. 74/// 75ExprResult Parser::ParseInitializerWithPotentialDesignator() { 76 77 // If this is the old-style GNU extension: 78 // designation ::= identifier ':' 79 // Handle it as a field designator. Otherwise, this must be the start of a 80 // normal expression. 81 if (Tok.is(tok::identifier)) { 82 const IdentifierInfo *FieldName = Tok.getIdentifierInfo(); 83 84 llvm::SmallString<256> NewSyntax; 85 llvm::raw_svector_ostream(NewSyntax) << '.' << FieldName->getName() 86 << " = "; 87 88 SourceLocation NameLoc = ConsumeToken(); // Eat the identifier. 89 90 assert(Tok.is(tok::colon) && "MayBeDesignationStart not working properly!"); 91 SourceLocation ColonLoc = ConsumeToken(); 92 93 Diag(NameLoc, diag::ext_gnu_old_style_field_designator) 94 << FixItHint::CreateReplacement(SourceRange(NameLoc, ColonLoc), 95 NewSyntax.str()); 96 97 Designation D; 98 D.AddDesignator(Designator::getField(FieldName, SourceLocation(), NameLoc)); 99 return Actions.ActOnDesignatedInitializer(D, ColonLoc, true, 100 ParseInitializer()); 101 } 102 103 // Desig - This is initialized when we see our first designator. We may have 104 // an objc message send with no designator, so we don't want to create this 105 // eagerly. 106 Designation Desig; 107 108 // Parse each designator in the designator list until we find an initializer. 109 while (Tok.is(tok::period) || Tok.is(tok::l_square)) { 110 if (Tok.is(tok::period)) { 111 // designator: '.' identifier 112 SourceLocation DotLoc = ConsumeToken(); 113 114 if (Tok.isNot(tok::identifier)) { 115 Diag(Tok.getLocation(), diag::err_expected_field_designator); 116 return ExprError(); 117 } 118 119 Desig.AddDesignator(Designator::getField(Tok.getIdentifierInfo(), DotLoc, 120 Tok.getLocation())); 121 ConsumeToken(); // Eat the identifier. 122 continue; 123 } 124 125 // We must have either an array designator now or an objc message send. 126 assert(Tok.is(tok::l_square) && "Unexpected token!"); 127 128 // Handle the two forms of array designator: 129 // array-designator: '[' constant-expression ']' 130 // array-designator: '[' constant-expression '...' constant-expression ']' 131 // 132 // Also, we have to handle the case where the expression after the 133 // designator an an objc message send: '[' objc-message-expr ']'. 134 // Interesting cases are: 135 // [foo bar] -> objc message send 136 // [foo] -> array designator 137 // [foo ... bar] -> array designator 138 // [4][foo bar] -> obsolete GNU designation with objc message send. 139 // 140 InMessageExpressionRAIIObject InMessage(*this, true); 141 142 BalancedDelimiterTracker T(*this, tok::l_square); 143 T.consumeOpen(); 144 SourceLocation StartLoc = T.getOpenLocation(); 145 146 ExprResult Idx; 147 148 // If Objective-C is enabled and this is a typename (class message 149 // send) or send to 'super', parse this as a message send 150 // expression. We handle C++ and C separately, since C++ requires 151 // much more complicated parsing. 152 if (getLang().ObjC1 && getLang().CPlusPlus) { 153 // Send to 'super'. 154 if (Tok.is(tok::identifier) && Tok.getIdentifierInfo() == Ident_super && 155 NextToken().isNot(tok::period) && 156 getCurScope()->isInObjcMethodScope()) { 157 CheckArrayDesignatorSyntax(*this, StartLoc, Desig); 158 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc, 159 ConsumeToken(), 160 ParsedType(), 161 0); 162 } 163 164 // Parse the receiver, which is either a type or an expression. 165 bool IsExpr; 166 void *TypeOrExpr; 167 if (ParseObjCXXMessageReceiver(IsExpr, TypeOrExpr)) { 168 SkipUntil(tok::r_square); 169 return ExprError(); 170 } 171 172 // If the receiver was a type, we have a class message; parse 173 // the rest of it. 174 if (!IsExpr) { 175 CheckArrayDesignatorSyntax(*this, StartLoc, Desig); 176 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc, 177 SourceLocation(), 178 ParsedType::getFromOpaquePtr(TypeOrExpr), 179 0); 180 } 181 182 // If the receiver was an expression, we still don't know 183 // whether we have a message send or an array designator; just 184 // adopt the expression for further analysis below. 185 // FIXME: potentially-potentially evaluated expression above? 186 Idx = ExprResult(static_cast<Expr*>(TypeOrExpr)); 187 } else if (getLang().ObjC1 && Tok.is(tok::identifier)) { 188 IdentifierInfo *II = Tok.getIdentifierInfo(); 189 SourceLocation IILoc = Tok.getLocation(); 190 ParsedType ReceiverType; 191 // Three cases. This is a message send to a type: [type foo] 192 // This is a message send to super: [super foo] 193 // This is a message sent to an expr: [super.bar foo] 194 switch (Sema::ObjCMessageKind Kind 195 = Actions.getObjCMessageKind(getCurScope(), II, IILoc, 196 II == Ident_super, 197 NextToken().is(tok::period), 198 ReceiverType)) { 199 case Sema::ObjCSuperMessage: 200 case Sema::ObjCClassMessage: 201 CheckArrayDesignatorSyntax(*this, StartLoc, Desig); 202 if (Kind == Sema::ObjCSuperMessage) 203 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc, 204 ConsumeToken(), 205 ParsedType(), 206 0); 207 ConsumeToken(); // the identifier 208 if (!ReceiverType) { 209 SkipUntil(tok::r_square); 210 return ExprError(); 211 } 212 213 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc, 214 SourceLocation(), 215 ReceiverType, 216 0); 217 218 case Sema::ObjCInstanceMessage: 219 // Fall through; we'll just parse the expression and 220 // (possibly) treat this like an Objective-C message send 221 // later. 222 break; 223 } 224 } 225 226 // Parse the index expression, if we haven't already gotten one 227 // above (which can only happen in Objective-C++). 228 // Note that we parse this as an assignment expression, not a constant 229 // expression (allowing *=, =, etc) to handle the objc case. Sema needs 230 // to validate that the expression is a constant. 231 // FIXME: We also need to tell Sema that we're in a 232 // potentially-potentially evaluated context. 233 if (!Idx.get()) { 234 Idx = ParseAssignmentExpression(); 235 if (Idx.isInvalid()) { 236 SkipUntil(tok::r_square); 237 return move(Idx); 238 } 239 } 240 241 // Given an expression, we could either have a designator (if the next 242 // tokens are '...' or ']' or an objc message send. If this is an objc 243 // message send, handle it now. An objc-message send is the start of 244 // an assignment-expression production. 245 if (getLang().ObjC1 && Tok.isNot(tok::ellipsis) && 246 Tok.isNot(tok::r_square)) { 247 CheckArrayDesignatorSyntax(*this, Tok.getLocation(), Desig); 248 return ParseAssignmentExprWithObjCMessageExprStart(StartLoc, 249 SourceLocation(), 250 ParsedType(), 251 Idx.take()); 252 } 253 254 // If this is a normal array designator, remember it. 255 if (Tok.isNot(tok::ellipsis)) { 256 Desig.AddDesignator(Designator::getArray(Idx.release(), StartLoc)); 257 } else { 258 // Handle the gnu array range extension. 259 Diag(Tok, diag::ext_gnu_array_range); 260 SourceLocation EllipsisLoc = ConsumeToken(); 261 262 ExprResult RHS(ParseConstantExpression()); 263 if (RHS.isInvalid()) { 264 SkipUntil(tok::r_square); 265 return move(RHS); 266 } 267 Desig.AddDesignator(Designator::getArrayRange(Idx.release(), 268 RHS.release(), 269 StartLoc, EllipsisLoc)); 270 } 271 272 T.consumeClose(); 273 Desig.getDesignator(Desig.getNumDesignators() - 1).setRBracketLoc( 274 T.getCloseLocation()); 275 } 276 277 // Okay, we're done with the designator sequence. We know that there must be 278 // at least one designator, because the only case we can get into this method 279 // without a designator is when we have an objc message send. That case is 280 // handled and returned from above. 281 assert(!Desig.empty() && "Designator is empty?"); 282 283 // Handle a normal designator sequence end, which is an equal. 284 if (Tok.is(tok::equal)) { 285 SourceLocation EqualLoc = ConsumeToken(); 286 return Actions.ActOnDesignatedInitializer(Desig, EqualLoc, false, 287 ParseInitializer()); 288 } 289 290 // We read some number of designators and found something that isn't an = or 291 // an initializer. If we have exactly one array designator, this 292 // is the GNU 'designation: array-designator' extension. Otherwise, it is a 293 // parse error. 294 if (Desig.getNumDesignators() == 1 && 295 (Desig.getDesignator(0).isArrayDesignator() || 296 Desig.getDesignator(0).isArrayRangeDesignator())) { 297 Diag(Tok, diag::ext_gnu_missing_equal_designator) 298 << FixItHint::CreateInsertion(Tok.getLocation(), "= "); 299 return Actions.ActOnDesignatedInitializer(Desig, Tok.getLocation(), 300 true, ParseInitializer()); 301 } 302 303 Diag(Tok, diag::err_expected_equal_designator); 304 return ExprError(); 305} 306 307 308/// ParseBraceInitializer - Called when parsing an initializer that has a 309/// leading open brace. 310/// 311/// initializer: [C99 6.7.8] 312/// '{' initializer-list '}' 313/// '{' initializer-list ',' '}' 314/// [GNU] '{' '}' 315/// 316/// initializer-list: 317/// designation[opt] initializer ...[opt] 318/// initializer-list ',' designation[opt] initializer ...[opt] 319/// 320ExprResult Parser::ParseBraceInitializer() { 321 InMessageExpressionRAIIObject InMessage(*this, false); 322 323 BalancedDelimiterTracker T(*this, tok::l_brace); 324 T.consumeOpen(); 325 SourceLocation LBraceLoc = T.getOpenLocation(); 326 327 /// InitExprs - This is the actual list of expressions contained in the 328 /// initializer. 329 ExprVector InitExprs(Actions); 330 331 if (Tok.is(tok::r_brace)) { 332 // Empty initializers are a C++ feature and a GNU extension to C. 333 if (!getLang().CPlusPlus) 334 Diag(LBraceLoc, diag::ext_gnu_empty_initializer); 335 // Match the '}'. 336 return Actions.ActOnInitList(LBraceLoc, MultiExprArg(Actions), 337 ConsumeBrace()); 338 } 339 340 bool InitExprsOk = true; 341 342 while (1) { 343 // Parse: designation[opt] initializer 344 345 // If we know that this cannot be a designation, just parse the nested 346 // initializer directly. 347 ExprResult SubElt; 348 if (MayBeDesignationStart(Tok.getKind(), PP)) 349 SubElt = ParseInitializerWithPotentialDesignator(); 350 else 351 SubElt = ParseInitializer(); 352 353 if (Tok.is(tok::ellipsis)) 354 SubElt = Actions.ActOnPackExpansion(SubElt.get(), ConsumeToken()); 355 356 // If we couldn't parse the subelement, bail out. 357 if (!SubElt.isInvalid()) { 358 InitExprs.push_back(SubElt.release()); 359 } else { 360 InitExprsOk = false; 361 362 // We have two ways to try to recover from this error: if the code looks 363 // grammatically ok (i.e. we have a comma coming up) try to continue 364 // parsing the rest of the initializer. This allows us to emit 365 // diagnostics for later elements that we find. If we don't see a comma, 366 // assume there is a parse error, and just skip to recover. 367 // FIXME: This comment doesn't sound right. If there is a r_brace 368 // immediately, it can't be an error, since there is no other way of 369 // leaving this loop except through this if. 370 if (Tok.isNot(tok::comma)) { 371 SkipUntil(tok::r_brace, false, true); 372 break; 373 } 374 } 375 376 // If we don't have a comma continued list, we're done. 377 if (Tok.isNot(tok::comma)) break; 378 379 // TODO: save comma locations if some client cares. 380 ConsumeToken(); 381 382 // Handle trailing comma. 383 if (Tok.is(tok::r_brace)) break; 384 } 385 386 bool closed = !T.consumeClose(); 387 388 if (InitExprsOk && closed) 389 return Actions.ActOnInitList(LBraceLoc, move_arg(InitExprs), 390 T.getCloseLocation()); 391 392 return ExprError(); // an error occurred. 393} 394 395