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llvm-project/clang/Parse/Parser.cpp

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//===--- Parser.cpp - C Language Family Parser ----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Parser interfaces.
//
//===----------------------------------------------------------------------===//
#include "clang/Parse/Parser.h"
#include "clang/Parse/DeclSpec.h"
#include "clang/Parse/Scope.h"
using namespace clang;
Parser::Parser(Preprocessor &pp, Action &actions)
: PP(pp), Actions(actions), Diags(PP.getDiagnostics()) {
Tok.setKind(tok::eof);
CurScope = 0;
NumCachedScopes = 0;
ParenCount = BracketCount = BraceCount = 0;
ObjCImpDecl = 0;
}
/// Out-of-line virtual destructor to provide home for Action class.
Action::~Action() {}
void Parser::Diag(SourceLocation Loc, unsigned DiagID,
const std::string &Msg) {
Diags.Report(FullSourceLoc(Loc,PP.getSourceManager()), DiagID, &Msg, 1);
}
/// MatchRHSPunctuation - For punctuation with a LHS and RHS (e.g. '['/']'),
/// this helper function matches and consumes the specified RHS token if
/// present. If not present, it emits the specified diagnostic indicating
/// that the parser failed to match the RHS of the token at LHSLoc. LHSName
/// should be the name of the unmatched LHS token.
SourceLocation Parser::MatchRHSPunctuation(tok::TokenKind RHSTok,
SourceLocation LHSLoc) {
if (Tok.is(RHSTok))
return ConsumeAnyToken();
SourceLocation R = Tok.getLocation();
const char *LHSName = "unknown";
diag::kind DID = diag::err_parse_error;
switch (RHSTok) {
default: break;
case tok::r_paren : LHSName = "("; DID = diag::err_expected_rparen; break;
case tok::r_brace : LHSName = "{"; DID = diag::err_expected_rbrace; break;
case tok::r_square: LHSName = "["; DID = diag::err_expected_rsquare; break;
case tok::greater: LHSName = "<"; DID = diag::err_expected_greater; break;
}
Diag(Tok, DID);
Diag(LHSLoc, diag::err_matching, LHSName);
SkipUntil(RHSTok);
return R;
}
/// ExpectAndConsume - The parser expects that 'ExpectedTok' is next in the
/// input. If so, it is consumed and false is returned.
///
/// If the input is malformed, this emits the specified diagnostic. Next, if
/// SkipToTok is specified, it calls SkipUntil(SkipToTok). Finally, true is
/// returned.
bool Parser::ExpectAndConsume(tok::TokenKind ExpectedTok, unsigned DiagID,
const char *Msg, tok::TokenKind SkipToTok) {
if (Tok.is(ExpectedTok)) {
ConsumeAnyToken();
return false;
}
Diag(Tok, DiagID, Msg);
if (SkipToTok != tok::unknown)
SkipUntil(SkipToTok);
return true;
}
//===----------------------------------------------------------------------===//
// Error recovery.
//===----------------------------------------------------------------------===//
/// SkipUntil - Read tokens until we get to the specified token, then consume
/// it (unless DontConsume is true). Because we cannot guarantee that the
/// token will ever occur, this skips to the next token, or to some likely
/// good stopping point. If StopAtSemi is true, skipping will stop at a ';'
/// character.
///
/// If SkipUntil finds the specified token, it returns true, otherwise it
/// returns false.
bool Parser::SkipUntil(const tok::TokenKind *Toks, unsigned NumToks,
bool StopAtSemi, bool DontConsume) {
// We always want this function to skip at least one token if the first token
// isn't T and if not at EOF.
bool isFirstTokenSkipped = true;
while (1) {
// If we found one of the tokens, stop and return true.
for (unsigned i = 0; i != NumToks; ++i) {
if (Tok.is(Toks[i])) {
if (DontConsume) {
// Noop, don't consume the token.
} else {
ConsumeAnyToken();
}
return true;
}
}
switch (Tok.getKind()) {
case tok::eof:
// Ran out of tokens.
return false;
case tok::l_paren:
// Recursively skip properly-nested parens.
ConsumeParen();
SkipUntil(tok::r_paren, false);
break;
case tok::l_square:
// Recursively skip properly-nested square brackets.
ConsumeBracket();
SkipUntil(tok::r_square, false);
break;
case tok::l_brace:
// Recursively skip properly-nested braces.
ConsumeBrace();
SkipUntil(tok::r_brace, false);
break;
// Okay, we found a ']' or '}' or ')', which we think should be balanced.
// Since the user wasn't looking for this token (if they were, it would
// already be handled), this isn't balanced. If there is a LHS token at a
// higher level, we will assume that this matches the unbalanced token
// and return it. Otherwise, this is a spurious RHS token, which we skip.
case tok::r_paren:
if (ParenCount && !isFirstTokenSkipped)
return false; // Matches something.
ConsumeParen();
break;
case tok::r_square:
if (BracketCount && !isFirstTokenSkipped)
return false; // Matches something.
ConsumeBracket();
break;
case tok::r_brace:
if (BraceCount && !isFirstTokenSkipped)
return false; // Matches something.
ConsumeBrace();
break;
case tok::string_literal:
case tok::wide_string_literal:
ConsumeStringToken();
break;
case tok::semi:
if (StopAtSemi)
return false;
// FALL THROUGH.
default:
// Skip this token.
ConsumeToken();
break;
}
isFirstTokenSkipped = false;
}
}
//===----------------------------------------------------------------------===//
// Scope manipulation
//===----------------------------------------------------------------------===//
/// EnterScope - Start a new scope.
void Parser::EnterScope(unsigned ScopeFlags) {
if (NumCachedScopes) {
Scope *N = ScopeCache[--NumCachedScopes];
N->Init(CurScope, ScopeFlags);
CurScope = N;
} else {
CurScope = new Scope(CurScope, ScopeFlags);
}
}
/// ExitScope - Pop a scope off the scope stack.
void Parser::ExitScope() {
assert(CurScope && "Scope imbalance!");
// Inform the actions module that this scope is going away if there are any
// decls in it.
if (!CurScope->decl_empty())
Actions.ActOnPopScope(Tok.getLocation(), CurScope);
Scope *OldScope = CurScope;
CurScope = OldScope->getParent();
if (NumCachedScopes == ScopeCacheSize)
delete OldScope;
else
ScopeCache[NumCachedScopes++] = OldScope;
}
//===----------------------------------------------------------------------===//
// C99 6.9: External Definitions.
//===----------------------------------------------------------------------===//
Parser::~Parser() {
// If we still have scopes active, delete the scope tree.
delete CurScope;
// Free the scope cache.
for (unsigned i = 0, e = NumCachedScopes; i != e; ++i)
delete ScopeCache[i];
}
/// Initialize - Warm up the parser.
///
void Parser::Initialize() {
// Prime the lexer look-ahead.
ConsumeToken();
// Create the translation unit scope. Install it as the current scope.
assert(CurScope == 0 && "A scope is already active?");
EnterScope(Scope::DeclScope);
Actions.ActOnTranslationUnitScope(Tok.getLocation(), CurScope);
if (Tok.is(tok::eof) &&
!getLang().CPlusPlus) // Empty source file is an extension in C
Diag(Tok, diag::ext_empty_source_file);
// Initialization for Objective-C context sensitive keywords recognition.
// Referenced in Parser::ParseObjCTypeQualifierList.
if (getLang().ObjC1) {
ObjCTypeQuals[objc_in] = &PP.getIdentifierTable().get("in");
ObjCTypeQuals[objc_out] = &PP.getIdentifierTable().get("out");
ObjCTypeQuals[objc_inout] = &PP.getIdentifierTable().get("inout");
ObjCTypeQuals[objc_oneway] = &PP.getIdentifierTable().get("oneway");
ObjCTypeQuals[objc_bycopy] = &PP.getIdentifierTable().get("bycopy");
ObjCTypeQuals[objc_byref] = &PP.getIdentifierTable().get("byref");
}
if (getLang().ObjC2) {
ObjCPropertyAttrs[objc_readonly] = &PP.getIdentifierTable().get("readonly");
ObjCPropertyAttrs[objc_getter] = &PP.getIdentifierTable().get("getter");
ObjCPropertyAttrs[objc_setter] = &PP.getIdentifierTable().get("setter");
ObjCPropertyAttrs[objc_assign] = &PP.getIdentifierTable().get("assign");
ObjCPropertyAttrs[objc_readwrite] =
&PP.getIdentifierTable().get("readwrite");
ObjCPropertyAttrs[objc_retain] = &PP.getIdentifierTable().get("retain");
ObjCPropertyAttrs[objc_copy] = &PP.getIdentifierTable().get("copy");
ObjCPropertyAttrs[objc_nonatomic] =
&PP.getIdentifierTable().get("nonatomic");
ObjCForCollectionInKW = &PP.getIdentifierTable().get("in");
}
}
/// ParseTopLevelDecl - Parse one top-level declaration, return whatever the
/// action tells us to. This returns true if the EOF was encountered.
bool Parser::ParseTopLevelDecl(DeclTy*& Result) {
Result = 0;
if (Tok.is(tok::eof)) return true;
Result = ParseExternalDeclaration();
return false;
}
/// Finalize - Shut down the parser.
///
void Parser::Finalize() {
ExitScope();
assert(CurScope == 0 && "Scope imbalance!");
}
/// ParseTranslationUnit:
/// translation-unit: [C99 6.9]
/// external-declaration
/// translation-unit external-declaration
void Parser::ParseTranslationUnit() {
Initialize();
DeclTy *Res;
while (!ParseTopLevelDecl(Res))
/*parse them all*/;
Finalize();
}
/// ParseExternalDeclaration:
/// external-declaration: [C99 6.9]
/// function-definition
/// declaration
/// [EXT] ';'
/// [GNU] asm-definition
/// [GNU] __extension__ external-declaration
/// [OBJC] objc-class-definition
/// [OBJC] objc-class-declaration
/// [OBJC] objc-alias-declaration
/// [OBJC] objc-protocol-definition
/// [OBJC] objc-method-definition
/// [OBJC] @end
///
/// [GNU] asm-definition:
/// simple-asm-expr ';'
///
Parser::DeclTy *Parser::ParseExternalDeclaration() {
switch (Tok.getKind()) {
case tok::semi:
Diag(Tok, diag::ext_top_level_semi);
ConsumeToken();
// TODO: Invoke action for top-level semicolon.
return 0;
case tok::kw___extension__: {
ConsumeToken();
// FIXME: Disable extension warnings.
DeclTy *RV = ParseExternalDeclaration();
// FIXME: Restore extension warnings.
return RV;
}
case tok::kw_asm: {
ExprResult Result = ParseSimpleAsm();
ExpectAndConsume(tok::semi, diag::err_expected_semi_after,
"top-level asm block");
if (!Result.isInvalid)
return Actions.ActOnFileScopeAsmDecl(Tok.getLocation(), Result.Val);
}
case tok::at:
// @ is not a legal token unless objc is enabled, no need to check.
return ParseObjCAtDirectives();
case tok::minus:
case tok::plus:
if (getLang().ObjC1)
return ParseObjCMethodDefinition();
else {
Diag(Tok, diag::err_expected_external_declaration);
ConsumeToken();
}
return 0;
case tok::kw_namespace:
case tok::kw_typedef:
// A function definition cannot start with a these keywords.
return ParseDeclaration(Declarator::FileContext);
default:
// We can't tell whether this is a function-definition or declaration yet.
return ParseDeclarationOrFunctionDefinition();
}
}
/// ParseDeclarationOrFunctionDefinition - Parse either a function-definition or
/// a declaration. We can't tell which we have until we read up to the
/// compound-statement in function-definition.
///
/// function-definition: [C99 6.9.1]
/// declaration-specifiers[opt] declarator declaration-list[opt]
/// compound-statement
/// declaration: [C99 6.7]
/// declaration-specifiers init-declarator-list[opt] ';'
/// [!C99] init-declarator-list ';' [TODO: warn in c99 mode]
/// [OMP] threadprivate-directive [TODO]
///
Parser::DeclTy *Parser::ParseDeclarationOrFunctionDefinition() {
// Parse the common declaration-specifiers piece.
DeclSpec DS;
ParseDeclarationSpecifiers(DS);
// C99 6.7.2.3p6: Handle "struct-or-union identifier;", "enum { X };"
// declaration-specifiers init-declarator-list[opt] ';'
if (Tok.is(tok::semi)) {
ConsumeToken();
return Actions.ParsedFreeStandingDeclSpec(CurScope, DS);
}
// ObjC2 allows prefix attributes on class interfaces.
if (getLang().ObjC2 && Tok.is(tok::at)) {
SourceLocation AtLoc = ConsumeToken(); // the "@"
if (!Tok.isObjCAtKeyword(tok::objc_interface)) {
Diag(Tok, diag::err_objc_expected_property_attr);//FIXME:better diagnostic
SkipUntil(tok::semi); // FIXME: better skip?
return 0;
}
const char *PrevSpec = 0;
if (DS.SetTypeSpecType(DeclSpec::TST_unspecified, AtLoc, PrevSpec))
Diag(AtLoc, diag::err_invalid_decl_spec_combination, PrevSpec);
return ParseObjCAtInterfaceDeclaration(AtLoc, DS.getAttributes());
}
// If the declspec consisted only of 'extern' and we have a string
// literal following it, this must be a C++ linkage specifier like
// 'extern "C"'.
if (Tok.is(tok::string_literal) && getLang().CPlusPlus &&
DS.getStorageClassSpec() == DeclSpec::SCS_extern &&
DS.getParsedSpecifiers() == DeclSpec::PQ_StorageClassSpecifier)
return ParseLinkage(Declarator::FileContext);
// Parse the first declarator.
Declarator DeclaratorInfo(DS, Declarator::FileContext);
ParseDeclarator(DeclaratorInfo);
// Error parsing the declarator?
if (DeclaratorInfo.getIdentifier() == 0) {
// If so, skip until the semi-colon or a }.
SkipUntil(tok::r_brace, true);
if (Tok.is(tok::semi))
ConsumeToken();
return 0;
}
// If the declarator is the start of a function definition, handle it.
if (Tok.is(tok::equal) || // int X()= -> not a function def
Tok.is(tok::comma) || // int X(), -> not a function def
Tok.is(tok::semi) || // int X(); -> not a function def
Tok.is(tok::kw_asm) || // int X() __asm__ -> not a function def
Tok.is(tok::kw___attribute)) { // int X() __attr__ -> not a function def
// FALL THROUGH.
} else if (DeclaratorInfo.isFunctionDeclarator() &&
(Tok.is(tok::l_brace) || // int X() {}
isDeclarationSpecifier())) { // int X(f) int f; {}
if (DS.getStorageClassSpec() == DeclSpec::SCS_typedef) {
Diag(Tok, diag::err_function_declared_typedef);
if (Tok.is(tok::l_brace)) {
// This recovery skips the entire function body. It would be nice
// to simply call ParseFunctionDefintion() below, however Sema
// assumes the declarator represents a function, not a typedef.
ConsumeBrace();
SkipUntil(tok::r_brace, true);
} else {
SkipUntil(tok::semi);
}
return 0;
}
return ParseFunctionDefinition(DeclaratorInfo);
} else {
if (DeclaratorInfo.isFunctionDeclarator())
Diag(Tok, diag::err_expected_fn_body);
else
Diag(Tok, diag::err_expected_after_declarator);
SkipUntil(tok::semi);
return 0;
}
// Parse the init-declarator-list for a normal declaration.
return ParseInitDeclaratorListAfterFirstDeclarator(DeclaratorInfo);
}
/// ParseFunctionDefinition - We parsed and verified that the specified
/// Declarator is well formed. If this is a K&R-style function, read the
/// parameters declaration-list, then start the compound-statement.
///
/// declaration-specifiers[opt] declarator declaration-list[opt]
/// compound-statement [TODO]
///
Parser::DeclTy *Parser::ParseFunctionDefinition(Declarator &D) {
const DeclaratorChunk &FnTypeInfo = D.getTypeObject(0);
assert(FnTypeInfo.Kind == DeclaratorChunk::Function &&
"This isn't a function declarator!");
const DeclaratorChunk::FunctionTypeInfo &FTI = FnTypeInfo.Fun;
// If this declaration was formed with a K&R-style identifier list for the
// arguments, parse declarations for all of the args next.
// int foo(a,b) int a; float b; {}
if (!FTI.hasPrototype && FTI.NumArgs != 0)
ParseKNRParamDeclarations(D);
// We should have an opening brace now.
if (Tok.isNot(tok::l_brace)) {
Diag(Tok, diag::err_expected_fn_body);
// Skip over garbage, until we get to '{'. Don't eat the '{'.
SkipUntil(tok::l_brace, true, true);
// If we didn't find the '{', bail out.
if (Tok.isNot(tok::l_brace))
return 0;
}
SourceLocation BraceLoc = Tok.getLocation();
// Enter a scope for the function body.
EnterScope(Scope::FnScope|Scope::DeclScope);
// Tell the actions module that we have entered a function definition with the
// specified Declarator for the function.
DeclTy *Res = Actions.ActOnStartOfFunctionDef(CurScope, D);
return ParseFunctionStatementBody(Res, BraceLoc, BraceLoc);
}
/// ParseKNRParamDeclarations - Parse 'declaration-list[opt]' which provides
/// types for a function with a K&R-style identifier list for arguments.
void Parser::ParseKNRParamDeclarations(Declarator &D) {
// We know that the top-level of this declarator is a function.
DeclaratorChunk::FunctionTypeInfo &FTI = D.getTypeObject(0).Fun;
// Read all the argument declarations.
while (isDeclarationSpecifier()) {
SourceLocation DSStart = Tok.getLocation();
// Parse the common declaration-specifiers piece.
DeclSpec DS;
ParseDeclarationSpecifiers(DS);
// C99 6.9.1p6: 'each declaration in the declaration list shall have at
// least one declarator'.
// NOTE: GCC just makes this an ext-warn. It's not clear what it does with
// the declarations though. It's trivial to ignore them, really hard to do
// anything else with them.
if (Tok.is(tok::semi)) {
Diag(DSStart, diag::err_declaration_does_not_declare_param);
ConsumeToken();
continue;
}
// C99 6.9.1p6: Declarations shall contain no storage-class specifiers other
// than register.
if (DS.getStorageClassSpec() != DeclSpec::SCS_unspecified &&
DS.getStorageClassSpec() != DeclSpec::SCS_register) {
Diag(DS.getStorageClassSpecLoc(),
diag::err_invalid_storage_class_in_func_decl);
DS.ClearStorageClassSpecs();
}
if (DS.isThreadSpecified()) {
Diag(DS.getThreadSpecLoc(),
diag::err_invalid_storage_class_in_func_decl);
DS.ClearStorageClassSpecs();
}
// Parse the first declarator attached to this declspec.
Declarator ParmDeclarator(DS, Declarator::KNRTypeListContext);
ParseDeclarator(ParmDeclarator);
// Handle the full declarator list.
while (1) {
DeclTy *AttrList;
// If attributes are present, parse them.
if (Tok.is(tok::kw___attribute))
// FIXME: attach attributes too.
AttrList = ParseAttributes();
// Ask the actions module to compute the type for this declarator.
Action::TypeResult TR =
Actions.ActOnParamDeclaratorType(CurScope, ParmDeclarator);
if (!TR.isInvalid &&
// A missing identifier has already been diagnosed.
ParmDeclarator.getIdentifier()) {
// Scan the argument list looking for the correct param to apply this
// type.
for (unsigned i = 0; ; ++i) {
// C99 6.9.1p6: those declarators shall declare only identifiers from
// the identifier list.
if (i == FTI.NumArgs) {
Diag(ParmDeclarator.getIdentifierLoc(), diag::err_no_matching_param,
ParmDeclarator.getIdentifier()->getName());
break;
}
if (FTI.ArgInfo[i].Ident == ParmDeclarator.getIdentifier()) {
// Reject redefinitions of parameters.
if (FTI.ArgInfo[i].TypeInfo) {
Diag(ParmDeclarator.getIdentifierLoc(),
diag::err_param_redefinition,
ParmDeclarator.getIdentifier()->getName());
} else {
FTI.ArgInfo[i].TypeInfo = TR.Val;
}
break;
}
}
}
// If we don't have a comma, it is either the end of the list (a ';') or
// an error, bail out.
if (Tok.isNot(tok::comma))
break;
// Consume the comma.
ConsumeToken();
// Parse the next declarator.
ParmDeclarator.clear();
ParseDeclarator(ParmDeclarator);
}
if (Tok.is(tok::semi)) {
ConsumeToken();
} else {
Diag(Tok, diag::err_parse_error);
// Skip to end of block or statement
SkipUntil(tok::semi, true);
if (Tok.is(tok::semi))
ConsumeToken();
}
}
// The actions module must verify that all arguments were declared.
}
/// ParseAsmStringLiteral - This is just a normal string-literal, but is not
/// allowed to be a wide string, and is not subject to character translation.
///
/// [GNU] asm-string-literal:
/// string-literal
///
Parser::ExprResult Parser::ParseAsmStringLiteral() {
if (!isTokenStringLiteral()) {
Diag(Tok, diag::err_expected_string_literal);
return true;
}
ExprResult Res = ParseStringLiteralExpression();
if (Res.isInvalid) return true;
// TODO: Diagnose: wide string literal in 'asm'
return Res;
}
/// ParseSimpleAsm
///
/// [GNU] simple-asm-expr:
/// 'asm' '(' asm-string-literal ')'
///
Parser::ExprResult Parser::ParseSimpleAsm() {
assert(Tok.is(tok::kw_asm) && "Not an asm!");
SourceLocation Loc = ConsumeToken();
if (Tok.isNot(tok::l_paren)) {
Diag(Tok, diag::err_expected_lparen_after, "asm");
return 0;
}
ConsumeParen();
ExprResult Result = ParseAsmStringLiteral();
MatchRHSPunctuation(tok::r_paren, Loc);
return Result;
}
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