/* vim: set ts=4 sw=4 tw=99 et:

 *

 * Copyright (C) 2012 David Anderson

 *

 * This file is part of SourcePawn.

 *

 * SourcePawn is free software: you can redistribute it and/or modify it under

 * the terms of the GNU General Public License as published by the Free

 * Software Foundation, either version 3 of the License, or (at your option)

 * any later version.

 * 

 * SourcePawn is distributed in the hope that it will be useful, but WITHOUT ANY

 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

 * FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * SourcePawn. If not, see http://www.gnu.org/licenses/.

 */

#include "AST.h"

#include "ConstantEvaluator.h"

using namespace ke;

static inline bool

EvaluateBinaryOperation(TokenKind kind, const BoxedPrimitive &left, const BoxedPrimitive &right,

                        BoxedPrimitive *out)

{

    switch (kind) {

      case TOK_PLUS:

        *out = BoxedPrimitive::Int(left.toInt() + right.toInt());

        return true;

      case TOK_SHL:

        *out = BoxedPrimitive::Int(left.toInt() << right.toInt());

        return true;

      default:

        return false;

    }

}

static inline bool

EvaluateUnaryOperation(TokenKind kind, const BoxedPrimitive &inner, BoxedPrimitive *out)

{

  switch (kind) {

    case TOK_MINUS:

      *out = BoxedPrimitive::Int(-inner.toInt());

      return true;

    default:

      return false;

  }

}

bool

ke::EvaluateForConstant(Expression *expr, BoxedPrimitive *out)

{

    switch (expr->kind()) {

      case AstNode::kBinaryExpression:

      {

        BoxedPrimitive left;

        BoxedPrimitive right;

        BinaryExpression *b = expr->toBinaryExpression();

        if (!EvaluateForConstant(b->left(), &left) ||

            !EvaluateForConstant(b->right(), &right))

        {

            return false;

        }

        return EvaluateBinaryOperation(b->token(), left, right, out);

      }

      case AstNode::kUnaryExpression:

      {

        BoxedPrimitive inner;

        UnaryExpression *u = expr->toUnaryExpression();

        if (!EvaluateForConstant(u->expression(), &inner))

            return false;

        return EvaluateUnaryOperation(u->token(), inner, out);

      }

      case AstNode::kBooleanLiteral:

        *out = BoxedPrimitive::Int(expr->toBooleanLiteral()->token() == TOK_TRUE ? 1 : 0);

        return true;

      case AstNode::kIntegerLiteral:

        *out = BoxedPrimitive::Int(expr->toIntegerLiteral()->value());

        return true;

      default:

        return false;

    }

}