137 lines
5.2 KiB
C#
137 lines
5.2 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="DodSequenceMerge.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.Generic;
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using System.Xml.XPath;
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using System.Diagnostics;
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using System.Globalization;
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using System.ComponentModel;
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namespace System.Xml.Xsl.Runtime {
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/// <summary>
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/// Merges several doc-order-distinct sequences into a single doc-order-distinct sequence.
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/// </summary>
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[EditorBrowsable(EditorBrowsableState.Never)]
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public struct DodSequenceMerge {
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private IList<XPathNavigator> firstSequence;
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private List<IEnumerator<XPathNavigator>> sequencesToMerge;
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private int nodeCount;
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private XmlQueryRuntime runtime;
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/// <summary>
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/// Initialize this instance of DodSequenceMerge.
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/// </summary>
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public void Create(XmlQueryRuntime runtime) {
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this.firstSequence = null;
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this.sequencesToMerge = null;
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this.nodeCount = 0;
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this.runtime = runtime;
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}
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/// <summary>
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/// Add a new sequence to the list of sequences to merge.
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/// </summary>
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public void AddSequence(IList<XPathNavigator> sequence) {
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// Ignore empty sequences
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if (sequence.Count == 0)
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return;
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if (this.firstSequence == null) {
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this.firstSequence = sequence;
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}
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else {
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if (this.sequencesToMerge == null) {
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this.sequencesToMerge = new List<IEnumerator<XPathNavigator>>();
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MoveAndInsertSequence(this.firstSequence.GetEnumerator());
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this.nodeCount = this.firstSequence.Count;
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}
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MoveAndInsertSequence(sequence.GetEnumerator());
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this.nodeCount += sequence.Count;
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}
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}
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/// <summary>
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/// Return the fully merged sequence.
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/// </summary>
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public IList<XPathNavigator> MergeSequences() {
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XmlQueryNodeSequence newSequence;
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// Zero sequences to merge
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if (this.firstSequence == null)
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return XmlQueryNodeSequence.Empty;
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// One sequence to merge
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if (this.sequencesToMerge == null || this.sequencesToMerge.Count <= 1)
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return this.firstSequence;
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// Two or more sequences to merge
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newSequence = new XmlQueryNodeSequence(this.nodeCount);
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while (this.sequencesToMerge.Count != 1) {
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// Save last item in list in temp variable, and remove it from list
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IEnumerator<XPathNavigator> sequence = this.sequencesToMerge[this.sequencesToMerge.Count - 1];
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this.sequencesToMerge.RemoveAt(this.sequencesToMerge.Count - 1);
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// Add current node to merged sequence
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newSequence.Add(sequence.Current);
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// Now move to the next node, and re-insert it into the list in reverse document order
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MoveAndInsertSequence(sequence);
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}
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// Add nodes in remaining sequence to end of list
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Debug.Assert(this.sequencesToMerge.Count == 1, "While loop should terminate when count == 1");
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do {
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newSequence.Add(this.sequencesToMerge[0].Current);
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}
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while (this.sequencesToMerge[0].MoveNext());
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return newSequence;
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}
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/// <summary>
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/// Move to the next item in the sequence. If there is no next item, then do not
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/// insert the sequence. Otherwise, call InsertSequence.
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/// </summary>
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private void MoveAndInsertSequence(IEnumerator<XPathNavigator> sequence) {
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if (sequence.MoveNext())
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InsertSequence(sequence);
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}
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/// <summary>
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/// Insert the specified sequence into the list of sequences to be merged.
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/// Insert it in reverse document order with respect to the current nodes in other sequences.
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/// </summary>
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private void InsertSequence(IEnumerator<XPathNavigator> sequence) {
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for (int i = this.sequencesToMerge.Count - 1; i >= 0; i--) {
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int cmp = this.runtime.ComparePosition(sequence.Current, this.sequencesToMerge[i].Current);
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if (cmp == -1) {
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// Insert after current item
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this.sequencesToMerge.Insert(i + 1, sequence);
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return;
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}
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else if (cmp == 0) {
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// Found duplicate, so skip the duplicate
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if (!sequence.MoveNext()) {
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// No more nodes, so don't insert anything
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return;
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}
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// Next node must be after current node in document order, so don't need to reset loop
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}
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}
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// Insert at beginning of list
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this.sequencesToMerge.Insert(0, sequence);
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}
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}
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}
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