llvm-project/clang/lib/Parse/ParseInit.cpp

260 lines
9.0 KiB
C++

//===--- ParseInit.cpp - Initializer Parsing ------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements initializer parsing as specified by C99 6.7.8.
//
//===----------------------------------------------------------------------===//
#include "clang/Parse/Designator.h"
#include "clang/Parse/Parser.h"
#include "clang/Basic/Diagnostic.h"
#include "llvm/ADT/SmallString.h"
using namespace clang;
/// MayBeDesignationStart - Return true if this token might be the start of a
/// designator. If we can tell it is impossible that it is a designator, return
/// false.
static bool MayBeDesignationStart(tok::TokenKind K) {
switch (K) {
default: return false;
case tok::period: // designator: '.' identifier
case tok::l_square: // designator: array-designator
case tok::identifier: // designation: identifier ':'
return true;
}
}
/// ParseInitializerWithPotentialDesignator - Parse the 'initializer' production
/// checking to see if the token stream starts with a designator.
///
/// designation:
/// designator-list '='
/// [GNU] array-designator
/// [GNU] identifier ':'
///
/// designator-list:
/// designator
/// designator-list designator
///
/// designator:
/// array-designator
/// '.' identifier
///
/// array-designator:
/// '[' constant-expression ']'
/// [GNU] '[' constant-expression '...' constant-expression ']'
///
/// NOTE: [OBC] allows '[ objc-receiver objc-message-args ]' as an
/// initializer (because it is an expression). We need to consider this case
/// when parsing array designators.
///
Parser::ExprResult Parser::
ParseInitializerWithPotentialDesignator(InitListDesignations &Designations,
unsigned InitNum) {
// If this is the old-style GNU extension:
// designation ::= identifier ':'
// Handle it as a field designator. Otherwise, this must be the start of a
// normal expression.
if (Tok.is(tok::identifier)) {
if (NextToken().is(tok::colon)) {
Diag(Tok, diag::ext_gnu_old_style_field_designator);
Designation &D = Designations.CreateDesignation(InitNum);
D.AddDesignator(Designator::getField(Tok.getIdentifierInfo()));
ConsumeToken(); // Eat the identifier.
assert(Tok.is(tok::colon) && "NextToken() not working properly!");
ConsumeToken();
return ParseInitializer();
}
// Otherwise, parse the assignment-expression.
return ParseAssignmentExpression();
}
// Parse each designator in the designator list until we find an initializer.
while (1) {
switch (Tok.getKind()) {
case tok::equal:
// We read some number (at least one due to the grammar we implemented)
// of designators and found an '=' sign. The following tokens must be
// the initializer.
ConsumeToken();
return ParseInitializer();
default: {
// We read some number (at least one due to the grammar we implemented)
// of designators and found something that isn't an = or an initializer.
// If we have exactly one array designator [TODO CHECK], this is the GNU
// 'designation: array-designator' extension. Otherwise, it is a parse
// error.
SourceLocation Loc = Tok.getLocation();
ExprResult Init = ParseInitializer();
if (Init.isInvalid) return Init;
Diag(Tok, diag::ext_gnu_missing_equal_designator);
return Init;
}
case tok::period:
// designator: '.' identifier
ConsumeToken();
if (ExpectAndConsume(tok::identifier, diag::err_expected_ident))
return ExprResult(true);
break;
case tok::l_square: {
// array-designator: '[' constant-expression ']'
// array-designator: '[' constant-expression '...' constant-expression ']'
// When designation is empty, this can be '[' objc-message-expr ']'. Note
// that we also have the case of [4][foo bar], which is the gnu designator
// extension + objc message send.
SourceLocation StartLoc = ConsumeBracket();
// If Objective-C is enabled and this is a typename or other identifier
// receiver, parse this as a message send expression.
if (getLang().ObjC1 && isTokObjCMessageIdentifierReceiver()) {
// FIXME: Emit ext_gnu_missing_equal_designator for inits like
// [4][foo bar].
IdentifierInfo *Name = Tok.getIdentifierInfo();
ConsumeToken();
return ParseAssignmentExprWithObjCMessageExprStart(StartLoc, Name, 0);
}
// Note that we parse this as an assignment expression, not a constant
// expression (allowing *=, =, etc) to handle the objc case. Sema needs
// to validate that the expression is a constant.
ExprResult Idx = ParseAssignmentExpression();
if (Idx.isInvalid) {
SkipUntil(tok::r_square);
return Idx;
}
// Given an expression, we could either have a designator (if the next
// tokens are '...' or ']' or an objc message send. If this is an objc
// message send, handle it now. An objc-message send is the start of
// an assignment-expression production.
if (getLang().ObjC1 && Tok.isNot(tok::ellipsis) &&
Tok.isNot(tok::r_square)) {
// FIXME: Emit ext_gnu_missing_equal_designator for inits like
// [4][foo bar].
return ParseAssignmentExprWithObjCMessageExprStart(StartLoc, 0,Idx.Val);
}
// Handle the gnu array range extension.
if (Tok.is(tok::ellipsis)) {
Diag(Tok, diag::ext_gnu_array_range);
ConsumeToken();
ExprResult RHS = ParseConstantExpression();
if (RHS.isInvalid) {
SkipUntil(tok::r_square);
return RHS;
}
}
MatchRHSPunctuation(tok::r_square, StartLoc);
break;
}
}
}
}
/// ParseInitializer
/// initializer: [C99 6.7.8]
/// assignment-expression
/// '{' initializer-list '}'
/// '{' initializer-list ',' '}'
/// [GNU] '{' '}'
///
/// initializer-list:
/// designation[opt] initializer
/// initializer-list ',' designation[opt] initializer
///
Parser::ExprResult Parser::ParseInitializer() {
// TODO: Split this up into ParseInitializer + ParseBraceInitializer, make
// ParseInitializer inline so that the non-brace case is short-cut.
if (Tok.isNot(tok::l_brace))
return ParseAssignmentExpression();
SourceLocation LBraceLoc = ConsumeBrace();
// We support empty initializers, but tell the user that they aren't using
// C99-clean code.
if (Tok.is(tok::r_brace)) {
Diag(LBraceLoc, diag::ext_gnu_empty_initializer);
// Match the '}'.
return Actions.ActOnInitList(LBraceLoc, 0, 0, ConsumeBrace());
}
/// InitExprs - This is the actual list of expressions contained in the
/// initializer.
llvm::SmallVector<ExprTy*, 8> InitExprs;
/// ExprDesignators - For each initializer, keep track of the designator that
/// was specified for it, if any.
InitListDesignations InitExprDesignations(Actions);
bool InitExprsOk = true;
while (1) {
// Parse: designation[opt] initializer
// If we know that this cannot be a designation, just parse the nested
// initializer directly.
ExprResult SubElt;
if (!MayBeDesignationStart(Tok.getKind()))
SubElt = ParseInitializer();
else
SubElt = ParseInitializerWithPotentialDesignator(InitExprDesignations,
InitExprs.size());
// If we couldn't parse the subelement, bail out.
if (!SubElt.isInvalid) {
InitExprs.push_back(SubElt.Val);
} else {
InitExprsOk = false;
// We have two ways to try to recover from this error: if the code looks
// gramatically ok (i.e. we have a comma coming up) try to continue
// parsing the rest of the initializer. This allows us to emit
// diagnostics for later elements that we find. If we don't see a comma,
// assume there is a parse error, and just skip to recover.
if (Tok.isNot(tok::comma)) {
SkipUntil(tok::r_brace, false, true);
break;
}
}
// If we don't have a comma continued list, we're done.
if (Tok.isNot(tok::comma)) break;
// TODO: save comma locations if some client cares.
ConsumeToken();
// Handle trailing comma.
if (Tok.is(tok::r_brace)) break;
}
if (InitExprsOk && Tok.is(tok::r_brace))
return Actions.ActOnInitList(LBraceLoc, &InitExprs[0], InitExprs.size(),
ConsumeBrace());
// On error, delete any parsed subexpressions.
for (unsigned i = 0, e = InitExprs.size(); i != e; ++i)
Actions.DeleteExpr(InitExprs[i]);
// Match the '}'.
MatchRHSPunctuation(tok::r_brace, LBraceLoc);
return ExprResult(true); // an error occurred.
}