lib/Parse/ParseExprCXX.cpp

//===--- ParseExprCXX.cpp - C++ Expression 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 the Expression parsing implementation for C++.
//
//===----------------------------------------------------------------------===//

#include "clang/Basic/Diagnostic.h"
#include "clang/Parse/Parser.h"
#include "clang/Parse/DeclSpec.h"
using namespace clang;

/// ParseCXXCasts - This handles the various ways to cast expressions to another
/// type.
///
///       postfix-expression: [C++ 5.2p1]
///         'dynamic_cast' '<' type-name '>' '(' expression ')'
///         'static_cast' '<' type-name '>' '(' expression ')'
///         'reinterpret_cast' '<' type-name '>' '(' expression ')'
///         'const_cast' '<' type-name '>' '(' expression ')'
///
Parser::ExprResult Parser::ParseCXXCasts() {
  tok::TokenKind Kind = Tok.getKind();
  const char *CastName = 0;     // For error messages

  switch (Kind) {
  default: assert(0 && "Unknown C++ cast!"); abort();
  case tok::kw_const_cast:       CastName = "const_cast";       break;
  case tok::kw_dynamic_cast:     CastName = "dynamic_cast";     break;
  case tok::kw_reinterpret_cast: CastName = "reinterpret_cast"; break;
  case tok::kw_static_cast:      CastName = "static_cast";      break;
  }

  SourceLocation OpLoc = ConsumeToken();
  SourceLocation LAngleBracketLoc = Tok.getLocation();

  if (ExpectAndConsume(tok::less, diag::err_expected_less_after, CastName))
    return ExprResult(true);

  TypeTy *CastTy = ParseTypeName();
  SourceLocation RAngleBracketLoc = Tok.getLocation();

  if (ExpectAndConsume(tok::greater, diag::err_expected_greater)) {
    Diag(LAngleBracketLoc, diag::err_matching, "<");
    return ExprResult(true);
  }

  SourceLocation LParenLoc = Tok.getLocation(), RParenLoc;

  if (Tok.isNot(tok::l_paren)) {
    Diag(Tok, diag::err_expected_lparen_after, CastName);
    return ExprResult(true);
  }

  ExprResult Result = ParseSimpleParenExpression(RParenLoc);

  if (!Result.isInvalid)
    Result = Actions.ActOnCXXCasts(OpLoc, Kind,
                                   LAngleBracketLoc, CastTy, RAngleBracketLoc,
                                   LParenLoc, Result.Val, RParenLoc);

  return Result;
}

/// ParseCXXBoolLiteral - This handles the C++ Boolean literals.
///
///       boolean-literal: [C++ 2.13.5]
///         'true'
///         'false'
Parser::ExprResult Parser::ParseCXXBoolLiteral() {
  tok::TokenKind Kind = Tok.getKind();
  return Actions.ActOnCXXBoolLiteral(ConsumeToken(), Kind);
}

/// ParseThrowExpression - This handles the C++ throw expression.
///
///       throw-expression: [C++ 15]
///         'throw' assignment-expression[opt]
Parser::ExprResult Parser::ParseThrowExpression() {
  assert(Tok.is(tok::kw_throw) && "Not throw!");
  SourceLocation ThrowLoc = ConsumeToken();           // Eat the throw token.
  
  // If the current token isn't the start of an assignment-expression,
  // then the expression is not present.  This handles things like:
  //   "C ? throw : (void)42", which is crazy but legal.
  switch (Tok.getKind()) {  // FIXME: move this predicate somewhere common.
  case tok::semi:
  case tok::r_paren:
  case tok::r_square:
  case tok::r_brace:
  case tok::colon:
  case tok::comma:
    return Actions.ActOnCXXThrow(ThrowLoc);

  default:
    ExprResult Expr = ParseAssignmentExpression();
    if (Expr.isInvalid) return Expr;
    return Actions.ActOnCXXThrow(ThrowLoc, Expr.Val);
  }
}

/// ParseCXXThis - This handles the C++ 'this' pointer.
///
/// C++ 9.3.2: In the body of a non-static member function, the keyword this is
/// a non-lvalue expression whose value is the address of the object for which
/// the function is called.
Parser::ExprResult Parser::ParseCXXThis() {
  assert(Tok.is(tok::kw_this) && "Not 'this'!");
  SourceLocation ThisLoc = ConsumeToken();
  return Actions.ActOnCXXThis(ThisLoc);
}

/// ParseCXXTypeConstructExpression - Parse construction of a specified type.
/// Can be interpreted either as function-style casting ("int(x)")
/// or class type construction ("ClassType(x,y,z)")
/// or creation of a value-initialized type ("int()").
///
///       postfix-expression: [C++ 5.2p1]
///         simple-type-specifier '(' expression-list[opt] ')'      [C++ 5.2.3]
///         typename-specifier '(' expression-list[opt] ')'         [TODO]
///
Parser::ExprResult Parser::ParseCXXTypeConstructExpression(const DeclSpec &DS) {
  Declarator DeclaratorInfo(DS, Declarator::TypeNameContext);
  TypeTy *TypeRep = Actions.ActOnTypeName(CurScope, DeclaratorInfo).Val;

  assert(Tok.is(tok::l_paren) && "Expected '('!");
  SourceLocation LParenLoc = ConsumeParen();

  ExprListTy Exprs;
  CommaLocsTy CommaLocs;

  if (Tok.isNot(tok::r_paren)) {
    if (ParseExpressionList(Exprs, CommaLocs)) {
      SkipUntil(tok::r_paren);
      return ExprResult(true);
    }
  }

  // Match the ')'.
  SourceLocation RParenLoc = MatchRHSPunctuation(tok::r_paren, LParenLoc);

  assert((Exprs.size() == 0 || Exprs.size()-1 == CommaLocs.size())&&
         "Unexpected number of commas!");
  return Actions.ActOnCXXTypeConstructExpr(DS.getSourceRange(), TypeRep,
                                           LParenLoc,
                                           &Exprs[0], Exprs.size(),
                                           &CommaLocs[0], RParenLoc);
}

/// ParseCXXCondition - if/switch/while/for condition expression.
///
///       condition:
///         expression
///         type-specifier-seq declarator '=' assignment-expression
/// [GNU]   type-specifier-seq declarator simple-asm-expr[opt] attributes[opt]
///             '=' assignment-expression
///
Parser::ExprResult Parser::ParseCXXCondition() {
  if (!isDeclarationSpecifier())
    return ParseExpression(); // expression

  SourceLocation StartLoc = Tok.getLocation();

  // type-specifier-seq
  DeclSpec DS;
  ParseSpecifierQualifierList(DS);

  // declarator
  Declarator DeclaratorInfo(DS, Declarator::ConditionContext);
  ParseDeclarator(DeclaratorInfo);

  // simple-asm-expr[opt]
  if (Tok.is(tok::kw_asm)) {
    ExprResult AsmLabel = ParseSimpleAsm();
    if (AsmLabel.isInvalid) {
      SkipUntil(tok::semi);
      return true;
    }
    DeclaratorInfo.setAsmLabel(AsmLabel.Val);
  }

  // If attributes are present, parse them.
  if (Tok.is(tok::kw___attribute))
    DeclaratorInfo.AddAttributes(ParseAttributes());

  // '=' assignment-expression
  if (Tok.isNot(tok::equal))
    return Diag(Tok, diag::err_expected_equal_after_declarator);
  SourceLocation EqualLoc = ConsumeToken();
  ExprResult AssignExpr = ParseAssignmentExpression();
  if (AssignExpr.isInvalid)
    return true;
  
  return Actions.ActOnCXXConditionDeclarationExpr(CurScope, StartLoc,
                                                  DeclaratorInfo,
                                                  EqualLoc, AssignExpr.Val);
}

/// ParseCXXSimpleTypeSpecifier - [C++ 7.1.5.2] Simple type specifiers.
/// This should only be called when the current token is known to be part of
/// simple-type-specifier.
///
///       simple-type-specifier:
///         '::'[opt] nested-name-specifier[opt] type-name                [TODO]
///         '::'[opt] nested-name-specifier 'template' simple-template-id [TODO]
///         char
///         wchar_t
///         bool
///         short
///         int
///         long
///         signed
///         unsigned
///         float
///         double
///         void
/// [GNU]   typeof-specifier
/// [C++0x] auto               [TODO]
///
///       type-name:
///         class-name
///         enum-name
///         typedef-name
///
void Parser::ParseCXXSimpleTypeSpecifier(DeclSpec &DS) {
  DS.SetRangeStart(Tok.getLocation());
  const char *PrevSpec;
  SourceLocation Loc = Tok.getLocation();
  
  switch (Tok.getKind()) {
  default: 
    assert(0 && "Not a simple-type-specifier token!");
    abort();
      
  // type-name
  case tok::identifier: {
    TypeTy *TypeRep = Actions.isTypeName(*Tok.getIdentifierInfo(), CurScope);
    assert(TypeRep && "Identifier wasn't a type-name!");
    DS.SetTypeSpecType(DeclSpec::TST_typedef, Loc, PrevSpec, TypeRep);
    break;
  }
    
  // builtin types
  case tok::kw_short:
    DS.SetTypeSpecWidth(DeclSpec::TSW_short, Loc, PrevSpec);
    break;
  case tok::kw_long:
    DS.SetTypeSpecWidth(DeclSpec::TSW_long, Loc, PrevSpec);
    break;
  case tok::kw_signed:
    DS.SetTypeSpecSign(DeclSpec::TSS_signed, Loc, PrevSpec);
    break;
  case tok::kw_unsigned:
    DS.SetTypeSpecSign(DeclSpec::TSS_unsigned, Loc, PrevSpec);
    break;
  case tok::kw_void:
    DS.SetTypeSpecType(DeclSpec::TST_void, Loc, PrevSpec);
    break;
  case tok::kw_char:
    DS.SetTypeSpecType(DeclSpec::TST_char, Loc, PrevSpec);
    break;
  case tok::kw_int:
    DS.SetTypeSpecType(DeclSpec::TST_int, Loc, PrevSpec);
    break;
  case tok::kw_float:
    DS.SetTypeSpecType(DeclSpec::TST_float, Loc, PrevSpec);
    break;
  case tok::kw_double:
    DS.SetTypeSpecType(DeclSpec::TST_double, Loc, PrevSpec);
    break;
  case tok::kw_wchar_t:
    DS.SetTypeSpecType(DeclSpec::TST_wchar, Loc, PrevSpec);
    break;
  case tok::kw_bool:
    DS.SetTypeSpecType(DeclSpec::TST_bool, Loc, PrevSpec);
    break;
  
  // GNU typeof support.
  case tok::kw_typeof:
    ParseTypeofSpecifier(DS);
    DS.Finish(Diags, PP.getSourceManager(), getLang());
    return;
  }
  DS.SetRangeEnd(Tok.getLocation());
  ConsumeToken();
  DS.Finish(Diags, PP.getSourceManager(), getLang());
}