source: stable/HeuristicLab.ExtLibs/HeuristicLab.NRefactory/5.5.0/NRefactory.CSharp-5.5.0/Refactoring/PatternHelper.cs

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// 
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// substantial portions of the Software.
// 
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// PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE
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using System;
using ICSharpCode.NRefactory.PatternMatching;
using ICSharpCode.NRefactory.TypeSystem;

namespace ICSharpCode.NRefactory.CSharp.Refactoring
{
  /// <summary>
  /// Helper class for constructing pattern ASTs.
  /// </summary>
  public class PatternHelper
  {
    /// <summary>
    /// Produces a choice pattern for <c>expr1 op expr2</c> or <c>expr2 op expr1</c>.
    /// </summary>
    public static Expression CommutativeOperator(Expression expr1, BinaryOperatorType op, Expression expr2)
    {
      return new Choice {
        new BinaryOperatorExpression(expr1, op, expr2),
        new BinaryOperatorExpression(expr2.Clone(), op, expr1.Clone())
      };
    }

    public static Expression CommutativeOperatorWithOptionalParentheses(Expression expr1, BinaryOperatorType op, Expression expr2)
    {
      return OptionalParentheses(CommutativeOperator(OptionalParentheses(expr1), op, OptionalParentheses(expr2)));
    }
    
    /// <summary>
    /// Optionally allows parentheses around the given expression.
    /// </summary>
    public static Expression OptionalParentheses(Expression expr)
    {
      return new OptionalParenthesesPattern(expr);
    }
    
    sealed class OptionalParenthesesPattern : Pattern
    {
      readonly INode child;
      
      public OptionalParenthesesPattern(INode child)
      {
        this.child = child;
      }
      
      public override bool DoMatch(INode other, Match match)
      {
        INode unpacked = ParenthesizedExpression.UnpackParenthesizedExpression(other as Expression);
        return child.DoMatch(unpacked, match);
      }
    }

    /// <summary>
    /// Optionally allow a block around the given statement;
    /// </summary>
    /// <returns>The statement.</returns>
    public static Statement EmbeddedStatement(Statement statement)
    {
      return new OptionalBlockPattern(statement);
    }

    sealed class OptionalBlockPattern : Pattern
    {
      readonly INode child;

      public OptionalBlockPattern(INode child)
      {
        this.child = child;
      }

      public override bool DoMatch(INode other, Match match)
      {
        INode unpacked = UnpackBlockStatement(other as Statement);
        return child.DoMatch(unpacked, match);
      }

      
      /// <summary>
      /// Unpacks the given expression if it is a ParenthesizedExpression, CheckedExpression or UncheckedExpression.
      /// </summary>
      public static Statement UnpackBlockStatement(Statement stmt)
      {
        while (stmt is BlockStatement) {
          stmt = stmt.GetChildByRole(BlockStatement.StatementRole);
          if (stmt.GetNextSibling(s => s.Role == BlockStatement.StatementRole) != null)
            return null;
        }
        return stmt;
      }
    }

  
    /// <summary>
    /// Allows to give parameter declaration group names.
    /// </summary>
    public static ParameterDeclaration NamedParameter(string groupName)
    {
      return new NamedParameterDeclaration (groupName);
    }

    /// <summary>
    /// Allows to give parameter declaration group names.
    /// </summary>
    public static ParameterDeclaration NamedParameter(string groupName, AstType type, string name, ParameterModifier modifier = ParameterModifier.None)
    {
      return new NamedParameterDeclaration (groupName, type, name, modifier);
    }

    sealed class NamedParameterDeclaration : ParameterDeclaration
    {
      readonly string groupName;
      public string GroupName {
        get { return groupName; }
      }

      public NamedParameterDeclaration(string groupName = null)
      {
        this.groupName = groupName;
      }

      public NamedParameterDeclaration(string groupName, AstType type, string name, ParameterModifier modifier = ParameterModifier.None) : base (type, name, modifier)
      {
        this.groupName = groupName;
      }

      protected internal override bool DoMatch(AstNode other, Match match)
      {
        match.Add(this.groupName, other);
        return base.DoMatch(other, match);
      }
    }

    /// <summary>
    /// Matches any type
    /// </summary>
    public static AstType AnyType (bool doesMatchNullTypes = false)
    {
      if (doesMatchNullTypes)
        return new OptionalNode(new AnyNode());
      else
        return new AnyNode();
    }

    /// <summary>
    /// Matches any type
    /// </summary>
    public static AstType AnyType (string groupName, bool doesMatchNullTypes = false)
    {
      if (doesMatchNullTypes)
        return new OptionalNode(new AnyNode(groupName));
      else
        return new AnyNode(groupName);
    }
  }
}