85 lines
3.1 KiB
C#
85 lines
3.1 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="QilReplaceVisitor.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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// <owner current="true" primary="true">[....]</owner>
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//------------------------------------------------------------------------------
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using System;
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using System.Collections;
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using System.Collections.Generic;
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using System.Diagnostics;
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using System.Xml.Xsl;
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namespace System.Xml.Xsl.Qil {
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/// <summary>
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/// Base internal class for visitors that replace the graph as they visit it.
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/// </summary>
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internal abstract class QilReplaceVisitor : QilVisitor {
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protected QilFactory f;
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public QilReplaceVisitor(QilFactory f) {
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this.f = f;
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}
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//-----------------------------------------------
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// QilVisitor overrides
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//-----------------------------------------------
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/// <summary>
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/// Visit all children of "parent", replacing each child with a copy of each child.
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/// </summary>
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protected override QilNode VisitChildren(QilNode parent) {
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XmlQueryType oldParentType = parent.XmlType;
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bool recalcType = false;
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// Visit children
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for (int i = 0; i < parent.Count; i++) {
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QilNode oldChild = parent[i], newChild;
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XmlQueryType oldChildType = oldChild != null ? oldChild.XmlType : null;
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// Visit child
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if (IsReference(parent, i))
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newChild = VisitReference(oldChild);
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else
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newChild = Visit(oldChild);
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// Only replace child and recalculate type if oldChild != newChild or oldChild.XmlType != newChild.XmlType
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if ((object) oldChild != (object) newChild || (newChild != null && (object) oldChildType != (object) newChild.XmlType)) {
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recalcType = true;
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parent[i] = newChild;
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}
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}
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if (recalcType)
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RecalculateType(parent, oldParentType);
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return parent;
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}
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//-----------------------------------------------
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// QilReplaceVisitor methods
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//-----------------------------------------------
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/// <summary>
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/// Once children have been replaced, the Xml type is recalculated.
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/// </summary>
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protected virtual void RecalculateType(QilNode node, XmlQueryType oldType) {
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XmlQueryType newType;
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newType = f.TypeChecker.Check(node);
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// Note the use of AtMost to account for cases when folding of Error nodes in the graph cause
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// cardinality to be recalculated.
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// For example, (Sequence (TextCtor (Error "error")) (Int32 1)) => (Sequence (Error "error") (Int32 1))
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// In this case, cardinality has gone from More to One
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Debug.Assert(newType.IsSubtypeOf(XmlQueryTypeFactory.AtMost(oldType, oldType.Cardinality)), "Replace shouldn't relax original type");
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node.XmlType = newType;
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}
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}
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}
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