1 //------------------------------------------------------------------------------
2 // <copyright file="KeyMatchBuilder.cs" company="Microsoft">
3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
4 // </copyright>
5 // <owner current="true" primary="true">Microsoft</owner>
6 //------------------------------------------------------------------------------
7 using System;
8 using System.Diagnostics;
9 using System.Collections;
10 using System.Collections.Generic;
11 using System.Xml;
12 using System.Xml.XPath;
13 using MS.Internal.Xml;
14 using System.Xml.Xsl.XPath;
15 using System.Xml.Xsl.Qil;
16 
17 namespace System.Xml.Xsl.Xslt {
18 
19     internal class KeyMatchBuilder : XPathBuilder, XPathPatternParser.IPatternBuilder {
20         private int depth = 0;
21         PathConvertor convertor;
22 
KeyMatchBuilder(IXPathEnvironment env)23         public KeyMatchBuilder(IXPathEnvironment env) : base(env) {
24             convertor = new PathConvertor(env.Factory);
25         }
26 
StartBuild()27         public override void StartBuild() {
28             Debug.Assert(0 <= depth && depth <= 1, "this shouldn't happen");
29             if (depth == 0) {
30                 base.StartBuild();
31             }
32             depth ++;
33         }
34 
EndBuild(QilNode result)35         public override QilNode EndBuild(QilNode result) {
36             depth --;
37             Debug.Assert(0 <= depth && depth <= 1, "this shouldn't happen");
38             if (result == null) { // special door to clean builder state in exception handlers
39                 return base.EndBuild(result);
40             }
41             if (depth == 0) {
42                 Debug.Assert(base.numFixupLast     == 0);
43                 Debug.Assert(base.numFixupPosition == 0);
44                 result = convertor.ConvertReletive2Absolute(result, base.fixupCurrent);
45                 result = base.EndBuild(result);
46             }
47             return result;
48         }
49 
50         // -------------------------------------- GetPredicateBuilder() ---------------------------------------
51 
GetPredicateBuilder(QilNode ctx)52         public virtual IXPathBuilder<QilNode> GetPredicateBuilder(QilNode ctx) {
53             return this;
54         }
55 
56         // This code depends on particula shapes that XPathBuilder generates.
57         // It works only on pathes.
58         // ToDo: We can do better here.
59         internal class PathConvertor : QilReplaceVisitor {
60             new XPathQilFactory f;
61             QilNode fixup;
PathConvertor(XPathQilFactory f)62             public PathConvertor(XPathQilFactory f) : base (f.BaseFactory) {
63                 this.f = f;
64             }
65 
ConvertReletive2Absolute(QilNode node, QilNode fixup)66             public QilNode ConvertReletive2Absolute(QilNode node, QilNode fixup) {
67                 QilDepthChecker.Check(node);
68                 Debug.Assert(node  != null);
69                 Debug.Assert(fixup != null);
70                 this.fixup = fixup;
71                 return this.Visit(node);
72             }
73 
74             // transparantly passing through Union and DocOrder
Visit(QilNode n)75             protected override QilNode Visit(QilNode n) {
76                 if (
77                     n.NodeType == QilNodeType.Union ||
78                     n.NodeType == QilNodeType.DocOrderDistinct ||
79                     n.NodeType == QilNodeType.Filter ||
80                     n.NodeType == QilNodeType.Loop
81                 ) {
82                     return base.Visit(n);
83                 }
84                 return n;
85             }
86             // Filers that travers Content being converted to global travers:
87             // Filter($j= ... Filter($i = Content(fixup), ...))  -> Filter($j= ... Filter($i = Loop($j = DesendentOrSelf(Root(fixup)), Content($j), ...)))
VisitLoop(QilLoop n)88             protected override QilNode VisitLoop(QilLoop n) {
89                 if (n.Variable.Binding.NodeType == QilNodeType.Root || n.Variable.Binding.NodeType == QilNodeType.Deref) {
90                     // This is absolute path already. We shouldn't touch it
91                     return n;
92                 }
93                 if (n.Variable.Binding.NodeType == QilNodeType.Content) {
94                     // This is "begin" of reletive path. Let's rewrite it as absolute:
95                     QilUnary content = (QilUnary)n.Variable.Binding;
96                     Debug.Assert(content.Child == this.fixup, "Unexpected content node");
97                     QilIterator it = f.For(f.DescendantOrSelf(f.Root(this.fixup)));
98                     content.Child = it;
99                     n.Variable.Binding = f.Loop(it, content);
100                     return n;
101                 }
102                 n.Variable.Binding = Visit(n.Variable.Binding);
103                 return n;
104             }
105 
VisitFilter(QilLoop n)106             protected override QilNode VisitFilter(QilLoop n) {
107                 return VisitLoop(n);
108             }
109         }
110     }
111 }
112