ExprResult Parser::ParseLambdaExpression() {
// Parse lambda-introducer.
LambdaIntroducer Intro;
- Optional<unsigned> DiagID = ParseLambdaIntroducer(Intro);
- if (DiagID) {
- Diag(Tok, DiagID.getValue());
+ if (ParseLambdaIntroducer(Intro)) {
SkipUntil(tok::r_square, StopAtSemi);
SkipUntil(tok::l_brace, StopAtSemi);
SkipUntil(tok::r_brace, StopAtSemi);
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.
+/// Use lookahead and potentially tentative parsing to determine if we are
+/// looking at a C++11 lambda expression, and parse it if we are.
///
/// If we are not looking at a lambda expression, returns ExprError().
ExprResult Parser::TryParseLambdaExpression() {
// If lookahead indicates an ObjC message send...
// [identifier identifier
- if (Next.is(tok::identifier) && After.is(tok::identifier)) {
+ if (Next.is(tok::identifier) && After.is(tok::identifier))
return ExprEmpty();
- }
// Here, we're stuck: lambda introducers and Objective-C message sends are
// unambiguous, but it requires arbitrary lookhead. [a,b,c,d,e,f,g] is a
// lambda, and [a,b,c,d,e,f,g h] is a Objective-C message send. Instead of
// writing two routines to parse a lambda introducer, just try to parse
// a lambda introducer first, and fall back if that fails.
- // (TryParseLambdaIntroducer never produces any diagnostic output.)
LambdaIntroducer Intro;
- if (TryParseLambdaIntroducer(Intro))
- return ExprEmpty();
+ {
+ TentativeParsingAction TPA(*this);
+ LambdaIntroducerTentativeParse Tentative;
+ if (ParseLambdaIntroducer(Intro, &Tentative)) {
+ TPA.Commit();
+ return ExprError();
+ }
+
+ switch (Tentative) {
+ case LambdaIntroducerTentativeParse::Success:
+ TPA.Commit();
+ break;
+
+ case LambdaIntroducerTentativeParse::Incomplete:
+ // Didn't fully parse the lambda-introducer, try again with a
+ // non-tentative parse.
+ TPA.Revert();
+ Intro = LambdaIntroducer();
+ if (ParseLambdaIntroducer(Intro))
+ return ExprError();
+ break;
+
+ case LambdaIntroducerTentativeParse::MessageSend:
+ case LambdaIntroducerTentativeParse::Invalid:
+ // Not a lambda-introducer, might be a message send.
+ TPA.Revert();
+ return ExprEmpty();
+ }
+ }
return ParseLambdaExpressionAfterIntroducer(Intro);
}
/// Parse a lambda introducer.
/// \param Intro A LambdaIntroducer filled in with information about the
/// contents of the lambda-introducer.
-/// \param SkippedInits If non-null, we are disambiguating between an Obj-C
-/// message send and a lambda expression. In this mode, we will
-/// sometimes skip the initializers for init-captures and not fully
-/// populate \p Intro. This flag will be set to \c true if we do so.
-/// \return A DiagnosticID if it hit something unexpected. The location for
-/// the diagnostic is that of the current token.
-Optional<unsigned> Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro,
- bool *SkippedInits) {
- typedef Optional<unsigned> DiagResult;
+/// \param Tentative If non-null, we are disambiguating between a
+/// lambda-introducer and some other construct. In this mode, we do not
+/// produce any diagnostics or take any other irreversible action unless
+/// we're sure that this is a lambda-expression.
+/// \return \c true if parsing (or disambiguation) failed with a diagnostic and
+/// the caller should bail out / recover.
+bool Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro,
+ LambdaIntroducerTentativeParse *Tentative) {
+ if (Tentative)
+ *Tentative = LambdaIntroducerTentativeParse::Success;
assert(Tok.is(tok::l_square) && "Lambda expressions begin with '['.");
BalancedDelimiterTracker T(*this, tok::l_square);
Intro.Range.setBegin(T.getOpenLocation());
- bool first = true;
+ bool First = true;
+
+ // Produce a diagnostic if we're not tentatively parsing; otherwise track
+ // that our parse has failed.
+ auto Invalid = [&](llvm::function_ref<void()> Action) {
+ if (Tentative) {
+ *Tentative = LambdaIntroducerTentativeParse::Invalid;
+ return false;
+ }
+ Action();
+ return true;
+ };
// Parse capture-default.
if (Tok.is(tok::amp) &&
(NextToken().is(tok::comma) || NextToken().is(tok::r_square))) {
Intro.Default = LCD_ByRef;
Intro.DefaultLoc = ConsumeToken();
- first = false;
+ First = false;
+ if (!Tok.getIdentifierInfo()) {
+ // This can only be a lambda; no need for tentative parsing any more.
+ // '[[and]]' can still be an attribute, though.
+ Tentative = nullptr;
+ }
} else if (Tok.is(tok::equal)) {
Intro.Default = LCD_ByCopy;
Intro.DefaultLoc = ConsumeToken();
- first = false;
+ First = false;
+ Tentative = nullptr;
}
while (Tok.isNot(tok::r_square)) {
- if (!first) {
+ if (!First) {
if (Tok.isNot(tok::comma)) {
// Provide a completion for a lambda introducer here. Except
// in Objective-C, where this is Almost Surely meant to be a message
// send. In that case, fail here and let the ObjC message
// expression parser perform the completion.
if (Tok.is(tok::code_completion) &&
- !(getLangOpts().ObjC && Intro.Default == LCD_None &&
- !Intro.Captures.empty())) {
+ !(getLangOpts().ObjC && Tentative)) {
Actions.CodeCompleteLambdaIntroducer(getCurScope(), Intro,
/*AfterAmpersand=*/false);
cutOffParsing();
break;
}
- return DiagResult(diag::err_expected_comma_or_rsquare);
+ return Invalid([&] {
+ Diag(Tok.getLocation(), diag::err_expected_comma_or_rsquare);
+ });
}
ConsumeToken();
}
if (Tok.is(tok::code_completion)) {
// If we're in Objective-C++ and we have a bare '[', then this is more
// likely to be a message receiver.
- if (getLangOpts().ObjC && first)
+ if (getLangOpts().ObjC && Tentative && First)
Actions.CodeCompleteObjCMessageReceiver(getCurScope());
else
Actions.CodeCompleteLambdaIntroducer(getCurScope(), Intro,
break;
}
- first = false;
+ First = false;
// Parse capture.
LambdaCaptureKind Kind = LCK_ByCopy;
ConsumeToken();
Kind = LCK_StarThis;
} else {
- return DiagResult(diag::err_expected_star_this_capture);
+ return Invalid([&] {
+ Diag(Tok.getLocation(), diag::err_expected_star_this_capture);
+ });
}
} else if (Tok.is(tok::kw_this)) {
Kind = LCK_This;
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);
+ return Invalid([&] {
+ // FIXME: Suggest a fixit here.
+ Diag(Tok.getLocation(), diag::err_this_captured_by_reference);
+ });
} else {
- return DiagResult(diag::err_expected_capture);
+ return Invalid([&] {
+ Diag(Tok.getLocation(), diag::err_expected_capture);
+ });
}
if (Tok.is(tok::l_paren)) {
ExprVector Exprs;
CommaLocsTy Commas;
- if (SkippedInits) {
+ if (Tentative) {
Parens.skipToEnd();
- *SkippedInits = true;
+ *Tentative = LambdaIntroducerTentativeParse::Incomplete;
} else if (ParseExpressionList(Exprs, Commas)) {
Parens.skipToEnd();
Init = ExprError();
else
InitKind = LambdaCaptureInitKind::ListInit;
- if (!SkippedInits) {
+ if (!Tentative) {
Init = ParseInitializer();
} else if (Tok.is(tok::l_brace)) {
BalancedDelimiterTracker Braces(*this, tok::l_brace);
Braces.consumeOpen();
Braces.skipToEnd();
- *SkippedInits = true;
+ *Tentative = LambdaIntroducerTentativeParse::Incomplete;
} else {
// We're disambiguating this:
//
ConsumeAnnotationToken();
}
}
- } else
+ } else {
TryConsumeToken(tok::ellipsis, EllipsisLoc);
+ }
}
+
+ // Check if this is a message send before we act on a possible init-capture.
+ if (Tentative && Tok.is(tok::identifier) &&
+ NextToken().isOneOf(tok::colon, tok::r_square)) {
+ // This can only be a message send. We're done with disambiguation.
+ *Tentative = LambdaIntroducerTentativeParse::MessageSend;
+ return false;
+ }
+
// If this is an init capture, process the initialization expression
// right away. For lambda init-captures such as the following:
// const int x = 10;
// that would be an error.
ParsedType InitCaptureType;
- if (!Init.isInvalid())
+ if (Tentative && Init.isUsable())
+ *Tentative = LambdaIntroducerTentativeParse::Incomplete;
+ else if (Init.isUsable()) {
Init = Actions.CorrectDelayedTyposInExpr(Init.get());
- if (Init.isUsable()) {
- // Get the pointer and store it in an lvalue, so we can use it as an
- // out argument.
- Expr *InitExpr = Init.get();
- // This performs any lvalue-to-rvalue conversions if necessary, which
- // can affect what gets captured in the containing decl-context.
- InitCaptureType = Actions.actOnLambdaInitCaptureInitialization(
- Loc, Kind == LCK_ByRef, Id, InitKind, InitExpr);
- Init = InitExpr;
+ if (Init.isUsable()) {
+ // Get the pointer and store it in an lvalue, so we can use it as an
+ // out argument.
+ Expr *InitExpr = Init.get();
+ // This performs any lvalue-to-rvalue conversions if necessary, which
+ // can affect what gets captured in the containing decl-context.
+ InitCaptureType = Actions.actOnLambdaInitCaptureInitialization(
+ Loc, Kind == LCK_ByRef, Id, InitKind, InitExpr);
+ Init = InitExpr;
+ }
}
SourceLocation LocEnd = PrevTokLocation;
T.consumeClose();
Intro.Range.setEnd(T.getCloseLocation());
- return DiagResult();
-}
-
-/// TryParseLambdaIntroducer - Tentatively parse a lambda introducer.
-///
-/// Returns true if it hit something unexpected.
-bool Parser::TryParseLambdaIntroducer(LambdaIntroducer &Intro) {
- {
- bool SkippedInits = false;
- TentativeParsingAction PA1(*this);
-
- if (ParseLambdaIntroducer(Intro, &SkippedInits)) {
- PA1.Revert();
- return true;
- }
-
- if (!SkippedInits) {
- PA1.Commit();
- return false;
- }
-
- PA1.Revert();
- }
-
- // Try to parse it again, but this time parse the init-captures too.
- Intro = LambdaIntroducer();
- TentativeParsingAction PA2(*this);
-
- if (!ParseLambdaIntroducer(Intro)) {
- PA2.Commit();
- return false;
- }
-
- PA2.Revert();
- return true;
+ return false;
}
static void
if (!Disambiguate && !getLangOpts().ObjC)
return CAK_AttributeSpecifier;
+ // '[[using ns: ...]]' is an attribute.
+ if (GetLookAheadToken(2).is(tok::kw_using))
+ return CAK_AttributeSpecifier;
+
RevertingTentativeParsingAction PA(*this);
// Opening brackets were checked for above.
ConsumeBracket();
- // Outside Obj-C++11, treat anything with a matching ']]' as an attribute.
if (!getLangOpts().ObjC) {
ConsumeBracket();
// 4) [[obj]{ return self; }() doStuff]; Lambda in message send.
// (1) is an attribute, (2) is ill-formed, and (3) and (4) are accepted.
- // If we have a lambda-introducer, then this is definitely not a message send.
+ // Check to see if this is a lambda-expression.
// FIXME: If this disambiguation is too slow, fold the tentative lambda parse
// into the tentative attribute parse below.
- LambdaIntroducer Intro;
- if (!TryParseLambdaIntroducer(Intro)) {
- // A lambda cannot end with ']]', and an attribute must.
- bool IsAttribute = Tok.is(tok::r_square);
-
- if (IsAttribute)
- // Case 1: C++11 attribute.
- return CAK_AttributeSpecifier;
+ {
+ RevertingTentativeParsingAction LambdaTPA(*this);
+ LambdaIntroducer Intro;
+ LambdaIntroducerTentativeParse Tentative;
+ if (ParseLambdaIntroducer(Intro, &Tentative)) {
+ // We hit a hard error after deciding this was not an attribute.
+ // FIXME: Don't parse and annotate expressions when disambiguating
+ // against an attribute.
+ return CAK_NotAttributeSpecifier;
+ }
- if (OuterMightBeMessageSend)
- // Case 4: Lambda in message send.
+ switch (Tentative) {
+ case LambdaIntroducerTentativeParse::MessageSend:
+ // Case 3: The inner construct is definitely a message send, so the
+ // outer construct is definitely not an attribute.
return CAK_NotAttributeSpecifier;
- // Case 2: Lambda in array size / index.
- return CAK_InvalidAttributeSpecifier;
+ case LambdaIntroducerTentativeParse::Success:
+ case LambdaIntroducerTentativeParse::Incomplete:
+ // This is a lambda-introducer or attribute-specifier.
+ if (Tok.is(tok::r_square))
+ // Case 1: C++11 attribute.
+ return CAK_AttributeSpecifier;
+
+ if (OuterMightBeMessageSend)
+ // Case 4: Lambda in message send.
+ return CAK_NotAttributeSpecifier;
+
+ // Case 2: Lambda in array size / index.
+ return CAK_InvalidAttributeSpecifier;
+
+ case LambdaIntroducerTentativeParse::Invalid:
+ // No idea what this is; we couldn't parse it as a lambda-introducer.
+ // Might still be an attribute-specifier or a message send.
+ break;
+ }
}
ConsumeBracket();
projects / clang / commitdiff