source: branches/2434_crossvalidation/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Ast/CSharpUtil.cs

// 
// CSharpUtil.cs
//  
// Author:
//       Mike KrÃŒger <mkrueger@novell.com>
// 
// Copyright (c) 2011 Novell, Inc (http://www.novell.com)
// 
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// 
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// 
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;
using ICSharpCode.NRefactory.CSharp;
using ICSharpCode.NRefactory.PatternMatching;

namespace ICSharpCode.NRefactory.CSharp
{
  public static class CSharpUtil
  {
    /// <summary>
    /// Inverts a boolean condition. Note: The condition object can be frozen (from AST) it's cloned internally.
    /// </summary>
    /// <param name="condition">The condition to invert.</param>
    public static Expression InvertCondition(Expression condition)
    {
      return InvertConditionInternal(condition);
    }
    
    static Expression InvertConditionInternal(Expression condition)
    {
      if (condition is ParenthesizedExpression) {
        return new ParenthesizedExpression(InvertCondition(((ParenthesizedExpression)condition).Expression));
      }
      
      if (condition is UnaryOperatorExpression) {
        var uOp = (UnaryOperatorExpression)condition;
        if (uOp.Operator == UnaryOperatorType.Not) {
          if (!(uOp.Parent is Expression))
            return GetInnerMostExpression(uOp.Expression).Clone();
          return uOp.Expression.Clone();
        }
        return new UnaryOperatorExpression(UnaryOperatorType.Not, uOp.Clone());
      }
      
      if (condition is BinaryOperatorExpression) {
        var bOp = (BinaryOperatorExpression)condition;

        if ((bOp.Operator == BinaryOperatorType.ConditionalAnd) || (bOp.Operator == BinaryOperatorType.ConditionalOr)) {
          return new BinaryOperatorExpression(InvertCondition(bOp.Left), NegateConditionOperator(bOp.Operator), InvertCondition(bOp.Right));
        } else if ((bOp.Operator == BinaryOperatorType.Equality) || (bOp.Operator == BinaryOperatorType.InEquality) || (bOp.Operator == BinaryOperatorType.GreaterThan)
          || (bOp.Operator == BinaryOperatorType.GreaterThanOrEqual) || (bOp.Operator == BinaryOperatorType.LessThan) || 
          (bOp.Operator == BinaryOperatorType.LessThanOrEqual)) {
          return new BinaryOperatorExpression(bOp.Left.Clone(), NegateRelationalOperator(bOp.Operator), bOp.Right.Clone());
        } else {
          var negatedOp = NegateRelationalOperator(bOp.Operator);
          if (negatedOp == BinaryOperatorType.Any)
            return new UnaryOperatorExpression(UnaryOperatorType.Not, new ParenthesizedExpression(condition.Clone()));
          bOp = (BinaryOperatorExpression)bOp.Clone();
          bOp.Operator = negatedOp;
          return bOp;
        }
      }
      if (condition is ConditionalExpression) {
        var cEx = condition.Clone() as ConditionalExpression;
        cEx.Condition = InvertCondition(cEx.Condition);
        return cEx;
      }
      if (condition is PrimitiveExpression) {
        var pex = condition as PrimitiveExpression;
        if (pex.Value is bool) {
          return new PrimitiveExpression(!((bool)pex.Value)); 
        }
      }
      
      return new UnaryOperatorExpression(UnaryOperatorType.Not, AddParensForUnaryExpressionIfRequired(condition.Clone()));
    }

    /// <summary>
    /// When negating an expression this is required, otherwise you would end up with
    /// a or b -> !a or b
    /// </summary>
    internal static Expression AddParensForUnaryExpressionIfRequired(Expression expression)
    {
      if ((expression is BinaryOperatorExpression) ||
          (expression is AssignmentExpression) ||
          (expression is CastExpression) ||
          (expression is AsExpression) ||
          (expression is IsExpression) ||
          (expression is LambdaExpression) ||
          (expression is ConditionalExpression)) {
        return new ParenthesizedExpression(expression);
      }

      return expression;
    }

    /// <summary>
    /// Get negation of the specified relational operator
    /// </summary>
    /// <returns>
    /// negation of the specified relational operator, or BinaryOperatorType.Any if it's not a relational operator
    /// </returns>
    public static BinaryOperatorType NegateRelationalOperator(BinaryOperatorType op)
    {
      switch (op) {
        case BinaryOperatorType.GreaterThan:
          return BinaryOperatorType.LessThanOrEqual;
        case BinaryOperatorType.GreaterThanOrEqual:
          return BinaryOperatorType.LessThan;
        case BinaryOperatorType.Equality:
          return BinaryOperatorType.InEquality;
        case BinaryOperatorType.InEquality:
          return BinaryOperatorType.Equality;
        case BinaryOperatorType.LessThan:
          return BinaryOperatorType.GreaterThanOrEqual;
        case BinaryOperatorType.LessThanOrEqual:
          return BinaryOperatorType.GreaterThan;
        case BinaryOperatorType.ConditionalOr:
          return BinaryOperatorType.ConditionalAnd;
        case BinaryOperatorType.ConditionalAnd:
          return BinaryOperatorType.ConditionalOr;
      }
      return BinaryOperatorType.Any;
    }

    /// <summary>
    /// Returns true, if the specified operator is a relational operator
    /// </summary>
    public static bool IsRelationalOperator(BinaryOperatorType op)
    {
      return NegateRelationalOperator(op) != BinaryOperatorType.Any;
    }

    /// <summary>
    /// Get negation of the condition operator
    /// </summary>
    /// <returns>
    /// negation of the specified condition operator, or BinaryOperatorType.Any if it's not a condition operator
    /// </returns>
    public static BinaryOperatorType NegateConditionOperator(BinaryOperatorType op)
    {
      switch (op) {
        case BinaryOperatorType.ConditionalOr:
          return BinaryOperatorType.ConditionalAnd;
        case BinaryOperatorType.ConditionalAnd:
          return BinaryOperatorType.ConditionalOr;
      }
      return BinaryOperatorType.Any;
    }

    public static bool AreConditionsEqual(Expression cond1, Expression cond2)
    {
      if (cond1 == null || cond2 == null)
        return false;
      return GetInnerMostExpression(cond1).IsMatch(GetInnerMostExpression(cond2));
    }

    public static Expression GetInnerMostExpression(Expression target)
    {
      while (target is ParenthesizedExpression)
        target = ((ParenthesizedExpression)target).Expression;
      return target;
    }
  }
}