Rule.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / Query / InternalTrees / Rule.cs / 1305376 / Rule.cs
                        
                        
                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
 
namespace System.Data.Query.InternalTrees
{ 
    ///  
    /// A Rule - more specifically, a transformation rule - describes an action that is to
    /// be taken when a specific kind of subtree is found in the tree 
    /// 
    internal abstract class Rule
    {
        ///  
        /// The "callback" function for each rule.
        /// Every callback function must return true if the subtree has 
        /// been modified (or a new subtree has been returned); and must return false 
        /// otherwise. If the root of the subtree has not changed, but some internal details
        /// of the subtree have changed, it is the responsibility of the rule to update any 
        /// local bookkeeping information.
        /// 
        /// The rule processing context
        /// the subtree to operate on 
        /// possibly transformed subtree
        /// transformation status - true, if there was some change; false otherwise 
        internal delegate bool ProcessNodeDelegate(RuleProcessingContext context, Node subTree, out Node newSubTree); 

        #region private state 
        private ProcessNodeDelegate m_nodeDelegate;
        private OpType m_opType;
        #endregion
 
        #region Constructors
        ///  
        /// Basic constructor 
        /// 
        /// The OpType we're interested in processing 
        /// The callback to invoke
        protected Rule(OpType opType, ProcessNodeDelegate nodeProcessDelegate)
        {
            Debug.Assert(nodeProcessDelegate != null, "null process delegate"); 
            Debug.Assert(opType != OpType.NotValid, "bad OpType");
            Debug.Assert(opType != OpType.Leaf, "bad OpType - Leaf"); 
 
            m_opType = opType;
            m_nodeDelegate = nodeProcessDelegate; 
        }
        #endregion

        #region protected methods 

        #endregion 
 
        #region public methods
        ///  
        /// Does the rule match the current node?
        /// 
        /// the node in question
        /// true, if a match was found 
        internal abstract bool Match(Node node);
 
        ///  
        /// We need to invoke the specified callback on the subtree in question - but only
        /// if the match succeeds 
        /// 
        /// Current rule processing context
        /// The node (subtree) to process
        /// the (possibly) modified subtree 
        /// true, if the subtree was modified
        internal bool Apply(RuleProcessingContext ruleProcessingContext, Node node, out Node newNode) 
        { 
            // invoke the real callback
            return m_nodeDelegate(ruleProcessingContext, node, out newNode); 
        }

        /// 
        /// The OpType we're interested in transforming 
        /// 
        internal OpType RuleOpType 
        { 
            get { return m_opType; }
        } 

#if DEBUG
        /// 
        /// The method name for the rule 
        /// 
        internal string MethodName 
        { 
            get { return m_nodeDelegate.Method.Name; }
        } 
#endif

        #endregion
    } 

    ///  
    /// A SimpleRule is a rule that specifies a specific OpType to look for, and an 
    /// appropriate action to take when such an Op is identified
    ///  
    internal sealed class SimpleRule : Rule
    {
        #region private state
        #endregion 

        #region constructors 
        ///  
        /// Basic constructor.
        ///  
        /// The OpType we're interested in
        /// The callback to invoke when we see such an Op
        internal SimpleRule(OpType opType, ProcessNodeDelegate processDelegate)
            : base(opType, processDelegate) 
        {
        } 
        #endregion 

        #region overriden methods 
        internal override bool Match(Node node)
        {
            return node.Op.OpType == this.RuleOpType;
        } 
        #endregion
    } 
 
    /// 
    /// A PatternMatchRule allows for a pattern to be specified to identify interesting 
    /// subtrees, rather than just an OpType
    /// 
    internal sealed class PatternMatchRule: Rule
    { 
        #region private state
        private Node m_pattern; 
        #endregion 

        #region constructors 
        /// 
        /// Basic constructor
        /// 
        /// The pattern to look for 
        /// The callback to invoke when such a pattern is identified
        internal PatternMatchRule(Node pattern, ProcessNodeDelegate processDelegate) 
            : base(pattern.Op.OpType, processDelegate) 
        {
            Debug.Assert(pattern != null, "null pattern"); 
            Debug.Assert(pattern.Op != null, "null pattern Op");
            m_pattern = pattern;
        }
        #endregion 

        #region private methods 
        private bool Match(Node pattern, Node original) 
        {
            if (pattern.Op.OpType == OpType.Leaf) 
                return true;
            if (pattern.Op.OpType != original.Op.OpType)
                return false;
            if (pattern.Children.Count != original.Children.Count) 
                return false;
            for (int i = 0; i < pattern.Children.Count; i++) 
                if (!Match(pattern.Children[i], original.Children[i])) 
                    return false;
            return true; 
        }
        #endregion

        #region overridden methods 
        internal override bool Match(Node node)
        { 
            return Match(m_pattern, node); 
        }
        #endregion 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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Rule.cs source code in C# .NET

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