Parsing of C++0x lambda expressions, from John Freeman with help from
David Blaikie!
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@136876 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Parse/ParseExprCXX.cpp b/lib/Parse/ParseExprCXX.cpp
index d88356c..757d86e 100644
--- a/lib/Parse/ParseExprCXX.cpp
+++ b/lib/Parse/ParseExprCXX.cpp
@@ -15,6 +15,7 @@
#include "clang/Parse/Parser.h"
#include "RAIIObjectsForParser.h"
#include "clang/Sema/DeclSpec.h"
+#include "clang/Sema/Scope.h"
#include "clang/Sema/ParsedTemplate.h"
#include "llvm/Support/ErrorHandling.h"
@@ -504,6 +505,266 @@
}
+/// ParseLambdaExpression - Parse a C++0x lambda expression.
+///
+/// lambda-expression:
+/// lambda-introducer lambda-declarator[opt] compound-statement
+///
+/// lambda-introducer:
+/// '[' lambda-capture[opt] ']'
+///
+/// lambda-capture:
+/// capture-default
+/// capture-list
+/// capture-default ',' capture-list
+///
+/// capture-default:
+/// '&'
+/// '='
+///
+/// capture-list:
+/// capture
+/// capture-list ',' capture
+///
+/// capture:
+/// identifier
+/// '&' identifier
+/// 'this'
+///
+/// lambda-declarator:
+/// '(' parameter-declaration-clause ')' attribute-specifier[opt]
+/// 'mutable'[opt] exception-specification[opt]
+/// trailing-return-type[opt]
+///
+ExprResult Parser::ParseLambdaExpression() {
+ // Parse lambda-introducer.
+ LambdaIntroducer Intro;
+
+ llvm::Optional<unsigned> DiagID(ParseLambdaIntroducer(Intro));
+ if (DiagID) {
+ Diag(Tok, DiagID.getValue());
+ SkipUntil(tok::r_square);
+ }
+
+ return ParseLambdaExpressionAfterIntroducer(Intro);
+}
+
+/// TryParseLambdaExpression - Use lookahead and potentially tentative
+/// parsing to determine if we are looking at a C++0x lambda expression, and parse
+/// it if we are.
+///
+/// If we are not looking at a lambda expression, returns ExprError().
+ExprResult Parser::TryParseLambdaExpression() {
+ assert(getLang().CPlusPlus0x
+ && Tok.is(tok::l_square)
+ && "Not at the start of a possible lambda expression.");
+
+ const Token Next = NextToken(), After = GetLookAheadToken(2);
+
+ // If lookahead indicates this is a lambda...
+ if (Next.is(tok::r_square) || // []
+ Next.is(tok::equal) || // [=
+ (Next.is(tok::amp) && // [&] or [&,
+ (After.is(tok::r_square) ||
+ After.is(tok::comma))) ||
+ (Next.is(tok::identifier) && // [identifier]
+ After.is(tok::r_square))) {
+ return ParseLambdaExpression();
+ }
+
+ // If lookahead indicates this is an Objective-C message...
+ if (Next.is(tok::identifier) && After.is(tok::identifier)) {
+ return ExprError();
+ }
+
+ LambdaIntroducer Intro;
+ if (TryParseLambdaIntroducer(Intro))
+ return ExprError();
+ return ParseLambdaExpressionAfterIntroducer(Intro);
+}
+
+/// ParseLambdaExpression - Parse a lambda introducer.
+///
+/// Returns a DiagnosticID if it hit something unexpected.
+llvm::Optional<unsigned> Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro) {
+ typedef llvm::Optional<unsigned> DiagResult;
+
+ assert(Tok.is(tok::l_square) && "Lambda expressions begin with '['.");
+ Intro.Range.setBegin(ConsumeBracket());
+
+ bool first = true;
+
+ // Parse capture-default.
+ if (Tok.is(tok::amp) &&
+ (NextToken().is(tok::comma) || NextToken().is(tok::r_square))) {
+ Intro.Default = LCD_ByRef;
+ ConsumeToken();
+ first = false;
+ } else if (Tok.is(tok::equal)) {
+ Intro.Default = LCD_ByCopy;
+ ConsumeToken();
+ first = false;
+ }
+
+ while (Tok.isNot(tok::r_square)) {
+ if (!first) {
+ if (Tok.isNot(tok::comma))
+ return DiagResult(diag::err_expected_comma_or_rsquare);
+ ConsumeToken();
+ }
+
+ first = false;
+
+ // Parse capture.
+ LambdaCaptureKind Kind = LCK_ByCopy;
+ SourceLocation Loc;
+ IdentifierInfo* Id = 0;
+
+ if (Tok.is(tok::kw_this)) {
+ Kind = LCK_This;
+ Loc = ConsumeToken();
+ } else {
+ if (Tok.is(tok::amp)) {
+ Kind = LCK_ByRef;
+ ConsumeToken();
+ }
+
+ if (Tok.is(tok::identifier)) {
+ Id = Tok.getIdentifierInfo();
+ Loc = ConsumeToken();
+ } else if (Tok.is(tok::kw_this)) {
+ // FIXME: If we want to suggest a fixit here, will need to return more
+ // than just DiagnosticID. Perhaps full DiagnosticBuilder that can be
+ // Clear()ed to prevent emission in case of tentative parsing?
+ return DiagResult(diag::err_this_captured_by_reference);
+ } else {
+ return DiagResult(diag::err_expected_capture);
+ }
+ }
+
+ Intro.addCapture(Kind, Loc, Id);
+ }
+
+ Intro.Range.setEnd(MatchRHSPunctuation(tok::r_square,
+ Intro.Range.getBegin()));
+
+ return DiagResult();
+}
+
+/// TryParseLambdaExpression - Tentatively parse a lambda introducer.
+///
+/// Returns true if it hit something unexpected.
+bool Parser::TryParseLambdaIntroducer(LambdaIntroducer &Intro) {
+ TentativeParsingAction PA(*this);
+
+ llvm::Optional<unsigned> DiagID(ParseLambdaIntroducer(Intro));
+
+ if (DiagID) {
+ PA.Revert();
+ return true;
+ }
+
+ PA.Commit();
+ return false;
+}
+
+/// ParseLambdaExpressionAfterIntroducer - Parse the rest of a lambda
+/// expression.
+ExprResult Parser::ParseLambdaExpressionAfterIntroducer(
+ LambdaIntroducer &Intro) {
+ // Parse lambda-declarator[opt].
+ DeclSpec DS(AttrFactory);
+ Declarator D(DS, Declarator::PrototypeContext);
+
+ if (Tok.is(tok::l_paren)) {
+ ParseScope PrototypeScope(this,
+ Scope::FunctionPrototypeScope |
+ Scope::DeclScope);
+
+ SourceLocation DeclLoc = ConsumeParen(), DeclEndLoc;
+
+ // Parse parameter-declaration-clause.
+ ParsedAttributes Attr(AttrFactory);
+ llvm::SmallVector<DeclaratorChunk::ParamInfo, 16> ParamInfo;
+ SourceLocation EllipsisLoc;
+
+ if (Tok.isNot(tok::r_paren))
+ ParseParameterDeclarationClause(D, Attr, ParamInfo, EllipsisLoc);
+
+ DeclEndLoc = MatchRHSPunctuation(tok::r_paren, DeclLoc);
+
+ // Parse 'mutable'[opt].
+ SourceLocation MutableLoc;
+ if (Tok.is(tok::kw_mutable)) {
+ MutableLoc = ConsumeToken();
+ DeclEndLoc = MutableLoc;
+ }
+
+ // Parse exception-specification[opt].
+ ExceptionSpecificationType ESpecType = EST_None;
+ SourceRange ESpecRange;
+ llvm::SmallVector<ParsedType, 2> DynamicExceptions;
+ llvm::SmallVector<SourceRange, 2> DynamicExceptionRanges;
+ ExprResult NoexceptExpr;
+ ESpecType = MaybeParseExceptionSpecification(ESpecRange,
+ DynamicExceptions,
+ DynamicExceptionRanges,
+ NoexceptExpr);
+
+ if (ESpecType != EST_None)
+ DeclEndLoc = ESpecRange.getEnd();
+
+ // Parse attribute-specifier[opt].
+ MaybeParseCXX0XAttributes(Attr, &DeclEndLoc);
+
+ // Parse trailing-return-type[opt].
+ ParsedType TrailingReturnType;
+ if (Tok.is(tok::arrow)) {
+ SourceRange Range;
+ TrailingReturnType = ParseTrailingReturnType(Range).get();
+ if (Range.getEnd().isValid())
+ DeclEndLoc = Range.getEnd();
+ }
+
+ PrototypeScope.Exit();
+
+ D.AddTypeInfo(DeclaratorChunk::getFunction(/*hasProto=*/true,
+ /*isVariadic=*/EllipsisLoc.isValid(),
+ EllipsisLoc,
+ ParamInfo.data(), ParamInfo.size(),
+ DS.getTypeQualifiers(),
+ /*RefQualifierIsLValueRef=*/true,
+ /*RefQualifierLoc=*/SourceLocation(),
+ MutableLoc,
+ ESpecType, ESpecRange.getBegin(),
+ DynamicExceptions.data(),
+ DynamicExceptionRanges.data(),
+ DynamicExceptions.size(),
+ NoexceptExpr.isUsable() ?
+ NoexceptExpr.get() : 0,
+ DeclLoc, DeclEndLoc, D,
+ TrailingReturnType),
+ Attr, DeclEndLoc);
+ }
+
+ // Parse compound-statement.
+ if (Tok.is(tok::l_brace)) {
+ // FIXME: Rename BlockScope -> ClosureScope if we decide to continue using
+ // it.
+ ParseScope BodyScope(this, Scope::BlockScope | Scope::FnScope |
+ Scope::BreakScope | Scope::ContinueScope |
+ Scope::DeclScope);
+
+ StmtResult Stmt(ParseCompoundStatementBody());
+
+ BodyScope.Exit();
+ } else {
+ Diag(Tok, diag::err_expected_lambda_body);
+ }
+
+ return ExprEmpty();
+}
+
/// ParseCXXCasts - This handles the various ways to cast expressions to another
/// type.
///