path: root/lib/Parse/ParseExpr.cpp

//===--- ParseExpr.cpp - 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.  Expressions in
// C99 basically consist of a bunch of binary operators with unary operators and
// other random stuff at the leaves.
//
// In the C99 grammar, these unary operators bind tightest and are represented
// as the 'cast-expression' production.  Everything else is either a binary
// operator (e.g. '/') or a ternary operator ("?:").  The unary leaves are
// handled by ParseCastExpression, the higher level pieces are handled by
// ParseBinaryExpression.
//
//===----------------------------------------------------------------------===//

#include "clang/Parse/Parser.h"
#include "clang/Parse/DeclSpec.h"
#include "clang/Parse/Scope.h"
#include "ExtensionRAIIObject.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/SmallString.h"
using namespace clang;

/// PrecedenceLevels - These are precedences for the binary/ternary operators in
/// the C99 grammar.  These have been named to relate with the C99 grammar
/// productions.  Low precedences numbers bind more weakly than high numbers.
namespace prec {
  enum Level {
    Unknown        = 0,    // Not binary operator.
    Comma          = 1,    // ,
    Assignment     = 2,    // =, *=, /=, %=, +=, -=, <<=, >>=, &=, ^=, |=
    Conditional    = 3,    // ?
    LogicalOr      = 4,    // ||
    LogicalAnd     = 5,    // &&
    InclusiveOr    = 6,    // |
    ExclusiveOr    = 7,    // ^
    And            = 8,    // &
    Equality       = 9,    // ==, !=
    Relational     = 10,   //  >=, <=, >, <
    Shift          = 11,   // <<, >>
    Additive       = 12,   // -, +
    Multiplicative = 13    // *, /, %
  };
}


/// getBinOpPrecedence - Return the precedence of the specified binary operator
/// token.  This returns:
///
static prec::Level getBinOpPrecedence(tok::TokenKind Kind) {
  switch (Kind) {
  default:                        return prec::Unknown;
  case tok::comma:                return prec::Comma;
  case tok::equal:
  case tok::starequal:
  case tok::slashequal:
  case tok::percentequal:
  case tok::plusequal:
  case tok::minusequal:
  case tok::lesslessequal:
  case tok::greatergreaterequal:
  case tok::ampequal:
  case tok::caretequal:
  case tok::pipeequal:            return prec::Assignment;
  case tok::question:             return prec::Conditional;
  case tok::pipepipe:             return prec::LogicalOr;
  case tok::ampamp:               return prec::LogicalAnd;
  case tok::pipe:                 return prec::InclusiveOr;
  case tok::caret:                return prec::ExclusiveOr;
  case tok::amp:                  return prec::And;
  case tok::exclaimequal:
  case tok::equalequal:           return prec::Equality;
  case tok::lessequal:
  case tok::less:
  case tok::greaterequal:
  case tok::greater:              return prec::Relational;
  case tok::lessless:
  case tok::greatergreater:       return prec::Shift;
  case tok::plus:
  case tok::minus:                return prec::Additive;
  case tok::percent:
  case tok::slash:
  case tok::star:                 return prec::Multiplicative;
  }
}


/// ParseExpression - Simple precedence-based parser for binary/ternary
/// operators.
///
/// Note: we diver