1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
//---------------------------------------------------------------------
// <copyright file="Rule.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//
// @owner Microsoft
// @backupOwner Microsoft
//---------------------------------------------------------------------
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
namespace System.Data.Query.InternalTrees
{
/// <summary>
/// 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
/// </summary>
internal abstract class Rule
{
/// <summary>
/// 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.
/// </summary>
/// <param name="context">The rule processing context</param>
/// <param name="subTree">the subtree to operate on</param>
/// <param name="newSubTree">possibly transformed subtree</param>
/// <returns>transformation status - true, if there was some change; false otherwise</returns>
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
/// <summary>
/// Basic constructor
/// </summary>
/// <param name="opType">The OpType we're interested in processing</param>
/// <param name="nodeProcessDelegate">The callback to invoke</param>
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
/// <summary>
/// Does the rule match the current node?
/// </summary>
/// <param name="node">the node in question</param>
/// <returns>true, if a match was found</returns>
internal abstract bool Match(Node node);
/// <summary>
/// We need to invoke the specified callback on the subtree in question - but only
/// if the match succeeds
/// </summary>
/// <param name="ruleProcessingContext">Current rule processing context</param>
/// <param name="node">The node (subtree) to process</param>
/// <param name="newNode">the (possibly) modified subtree</param>
/// <returns>true, if the subtree was modified</returns>
internal bool Apply(RuleProcessingContext ruleProcessingContext, Node node, out Node newNode)
{
// invoke the real callback
return m_nodeDelegate(ruleProcessingContext, node, out newNode);
}
/// <summary>
/// The OpType we're interested in transforming
/// </summary>
internal OpType RuleOpType
{
get { return m_opType; }
}
#if DEBUG
/// <summary>
/// The method name for the rule
/// </summary>
internal string MethodName
{
get { return m_nodeDelegate.Method.Name; }
}
#endif
#endregion
}
/// <summary>
/// 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
/// </summary>
internal sealed class SimpleRule : Rule
{
#region private state
#endregion
#region constructors
/// <summary>
/// Basic constructor.
/// </summary>
/// <param name="opType">The OpType we're interested in</param>
/// <param name="processDelegate">The callback to invoke when we see such an Op</param>
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
}
/// <summary>
/// A PatternMatchRule allows for a pattern to be specified to identify interesting
/// subtrees, rather than just an OpType
/// </summary>
internal sealed class PatternMatchRule: Rule
{
#region private state
private Node m_pattern;
#endregion
#region constructors
/// <summary>
/// Basic constructor
/// </summary>
/// <param name="pattern">The pattern to look for</param>
/// <param name="processDelegate">The callback to invoke when such a pattern is identified</param>
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
}
}
|
