469 lines
17 KiB
C#
469 lines
17 KiB
C#
//------------------------------------------------------------------------------
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// <copyright file="XPathNodeInfoAtom.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">Microsoft</owner>
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//------------------------------------------------------------------------------
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using System.Collections;
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using System.Text;
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using System.Xml;
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using System.Xml.Schema;
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using System.Xml.XPath;
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using System.Diagnostics;
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namespace MS.Internal.Xml.Cache {
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/// <summary>
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/// The 0th node in each page contains a non-null reference to an XPathNodePageInfo internal class that provides
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/// information about that node's page. The other fields in the 0th node are undefined and should never
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/// be used.
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/// </summary>
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sealed internal class XPathNodePageInfo {
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private int pageNum;
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private int nodeCount;
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private XPathNode[] pagePrev;
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private XPathNode[] pageNext;
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/// <summary>
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/// Constructor.
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/// </summary>
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public XPathNodePageInfo(XPathNode[] pagePrev, int pageNum) {
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this.pagePrev = pagePrev;
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this.pageNum = pageNum;
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this.nodeCount = 1; // Every node page contains PageInfo at 0th position
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}
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/// <summary>
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/// Return the sequential page number of the page containing nodes that share this information atom.
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/// </summary>
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public int PageNumber {
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get { return this.pageNum; }
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}
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/// <summary>
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/// Return the number of nodes allocated in this page.
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/// </summary>
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public int NodeCount {
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get { return this.nodeCount; }
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set { this.nodeCount = value; }
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}
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/// <summary>
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/// Return the previous node page in the document.
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/// </summary>
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public XPathNode[] PreviousPage {
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get { return this.pagePrev; }
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}
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/// <summary>
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/// Return the next node page in the document.
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/// </summary>
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public XPathNode[] NextPage {
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get { return this.pageNext; }
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set { this.pageNext = value; }
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}
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}
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/// <summary>
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/// There is a great deal of redundancy in typical Xml documents. Even in documents with thousands or millions
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/// of nodes, there are a small number of common names and types. And since nodes are allocated in pages in
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/// document order, nodes on the same page with the same name and type are likely to have the same sibling and
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/// parent pages as well.
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/// Redundant information is shared by creating immutable, atomized objects. This is analogous to the
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/// string.Intern() operation. If a node's name, type, or parent/sibling pages are modified, then a new
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/// InfoAtom needs to be obtained, since other nodes may still be referencing the old InfoAtom.
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/// </summary>
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sealed internal class XPathNodeInfoAtom {
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private string localName;
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private string namespaceUri;
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private string prefix;
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private string baseUri;
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private XPathNode[] pageParent;
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private XPathNode[] pageSibling;
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private XPathNode[] pageSimilar;
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private XPathDocument doc;
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private int lineNumBase;
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private int linePosBase;
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private int hashCode;
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private int localNameHash;
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private XPathNodeInfoAtom next;
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private XPathNodePageInfo pageInfo;
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/// <summary>
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/// Construct information for the 0th node in each page. The only field which is defined is this.pageInfo,
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/// and it contains information about that page (pageNum, nextPage, etc.).
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/// </summary>
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public XPathNodeInfoAtom(XPathNodePageInfo pageInfo) {
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this.pageInfo = pageInfo;
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}
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/// <summary>
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/// Construct a new shared information atom. This method should only be used by the XNodeInfoTable.
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/// </summary>
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public XPathNodeInfoAtom(string localName, string namespaceUri, string prefix, string baseUri,
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XPathNode[] pageParent, XPathNode[] pageSibling, XPathNode[] pageSimilar,
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XPathDocument doc, int lineNumBase, int linePosBase) {
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Init(localName, namespaceUri, prefix, baseUri, pageParent, pageSibling, pageSimilar, doc, lineNumBase, linePosBase);
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}
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/// <summary>
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/// Initialize an existing shared information atom. This method should only be used by the XNodeInfoTable.
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/// </summary>
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public void Init(string localName, string namespaceUri, string prefix, string baseUri,
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XPathNode[] pageParent, XPathNode[] pageSibling, XPathNode[] pageSimilar,
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XPathDocument doc, int lineNumBase, int linePosBase) {
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Debug.Assert(localName != null && namespaceUri != null && prefix != null && doc != null);
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this.localName = localName;
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this.namespaceUri = namespaceUri;
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this.prefix = prefix;
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this.baseUri = baseUri;
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this.pageParent = pageParent;
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this.pageSibling = pageSibling;
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this.pageSimilar = pageSimilar;
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this.doc = doc;
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this.lineNumBase = lineNumBase;
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this.linePosBase = linePosBase;
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this.next = null;
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this.pageInfo = null;
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this.hashCode = 0;
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this.localNameHash = 0;
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for (int i = 0; i < this.localName.Length; i++)
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this.localNameHash += (this.localNameHash << 7) ^ this.localName[i];
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}
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/// <summary>
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/// Returns information about the node page. Only the 0th node on each page has this property defined.
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/// </summary>
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public XPathNodePageInfo PageInfo {
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get { return this.pageInfo; }
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}
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/// <summary>
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/// Return the local name part of nodes that share this information atom.
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/// </summary>
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public string LocalName {
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get { return this.localName; }
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}
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/// <summary>
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/// Return the namespace name part of nodes that share this information atom.
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/// </summary>
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public string NamespaceUri {
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get { return this.namespaceUri; }
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}
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/// <summary>
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/// Return the prefix name part of nodes that share this information atom.
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/// </summary>
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public string Prefix {
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get { return this.prefix; }
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}
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/// <summary>
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/// Return the base Uri of nodes that share this information atom.
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/// </summary>
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public string BaseUri {
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get { return this.baseUri; }
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}
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/// <summary>
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/// Return the page containing the next sibling of nodes that share this information atom.
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/// </summary>
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public XPathNode[] SiblingPage {
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get { return this.pageSibling; }
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}
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/// <summary>
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/// Return the page containing the next element having a name which has same hashcode as this element.
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/// </summary>
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public XPathNode[] SimilarElementPage {
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get { return this.pageSimilar; }
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}
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/// <summary>
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/// Return the page containing the parent of nodes that share this information atom.
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/// </summary>
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public XPathNode[] ParentPage {
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get { return this.pageParent; }
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}
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/// <summary>
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/// Return the page containing the owner document of nodes that share this information atom.
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/// </summary>
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public XPathDocument Document {
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get { return this.doc; }
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}
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/// <summary>
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/// Return the line number to which a line number offset stored in the XPathNode is added.
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/// </summary>
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public int LineNumberBase {
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get { return this.lineNumBase; }
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}
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/// <summary>
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/// Return the line position to which a line position offset stored in the XPathNode is added.
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/// </summary>
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public int LinePositionBase {
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get { return this.linePosBase; }
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}
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/// <summary>
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/// Return cached hash code of the local name of nodes which share this information atom.
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/// </summary>
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public int LocalNameHashCode {
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get { return this.localNameHash; }
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}
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/// <summary>
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/// Link together InfoAtoms that hash to the same hashtable bucket (should only be used by XPathNodeInfoTable)
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/// </summary>
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public XPathNodeInfoAtom Next {
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get { return this.next; }
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set { this.next = value; }
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}
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/// <summary>
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/// Return this information atom's hash code, previously computed for performance.
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/// </summary>
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public override int GetHashCode() {
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if (this.hashCode == 0) {
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int hashCode;
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// Start with local name
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hashCode = this.localNameHash;
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// Add page indexes
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if (this.pageSibling != null)
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hashCode += (hashCode << 7) ^ this.pageSibling[0].PageInfo.PageNumber;
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if (this.pageParent != null)
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hashCode += (hashCode << 7) ^ this.pageParent[0].PageInfo.PageNumber;
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if (this.pageSimilar != null)
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hashCode += (hashCode << 7) ^ this.pageSimilar[0].PageInfo.PageNumber;
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// Save hashcode. Don't save 0, so that it won't ever be recomputed.
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this.hashCode = ((hashCode == 0) ? 1 : hashCode);
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}
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return this.hashCode;
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}
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/// <summary>
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/// Return true if this InfoAtom has the same values as another InfoAtom.
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/// </summary>
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public override bool Equals(object other) {
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XPathNodeInfoAtom that = other as XPathNodeInfoAtom;
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Debug.Assert(that != null);
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Debug.Assert((object) this.doc == (object) that.doc);
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Debug.Assert(this.pageInfo == null);
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// Assume that name parts are atomized
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if (this.GetHashCode() == that.GetHashCode()) {
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if ((object) this.localName == (object) that.localName &&
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(object) this.pageSibling == (object) that.pageSibling &&
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(object) this.namespaceUri == (object) that.namespaceUri &&
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(object) this.pageParent == (object) that.pageParent &&
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(object) this.pageSimilar == (object) that.pageSimilar &&
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(object) this.prefix == (object) that.prefix &&
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(object) this.baseUri == (object) that.baseUri &&
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this.lineNumBase == that.lineNumBase &&
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this.linePosBase == that.linePosBase) {
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return true;
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}
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}
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return false;
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}
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/// <summary>
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/// Return InfoAtom formatted as a string:
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/// hash=xxx, {http://my.com}foo:bar, parent=1, sibling=1, lineNum=0, linePos=0
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/// </summary>
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public override string ToString() {
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StringBuilder bldr = new StringBuilder();
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bldr.Append("hash=");
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bldr.Append(GetHashCode());
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bldr.Append(", ");
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if (this.localName.Length != 0) {
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bldr.Append('{');
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bldr.Append(this.namespaceUri);
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bldr.Append('}');
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if (this.prefix.Length != 0) {
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bldr.Append(this.prefix);
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bldr.Append(':');
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}
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bldr.Append(this.localName);
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bldr.Append(", ");
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}
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if (this.pageParent != null) {
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bldr.Append("parent=");
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bldr.Append(this.pageParent[0].PageInfo.PageNumber);
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bldr.Append(", ");
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}
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if (this.pageSibling != null) {
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bldr.Append("sibling=");
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bldr.Append(this.pageSibling[0].PageInfo.PageNumber);
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bldr.Append(", ");
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}
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if (this.pageSimilar != null) {
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bldr.Append("similar=");
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bldr.Append(this.pageSimilar[0].PageInfo.PageNumber);
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bldr.Append(", ");
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}
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bldr.Append("lineNum=");
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bldr.Append(this.lineNumBase);
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bldr.Append(", ");
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bldr.Append("linePos=");
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bldr.Append(this.linePosBase);
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return bldr.ToString();
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}
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}
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/// <summary>
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/// An atomization table for XPathNodeInfoAtom.
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/// </summary>
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sealed internal class XPathNodeInfoTable {
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private XPathNodeInfoAtom[] hashTable;
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private int sizeTable;
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private XPathNodeInfoAtom infoCached;
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#if DEBUG
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private const int DefaultTableSize = 2;
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#else
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private const int DefaultTableSize = 32;
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#endif
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/// <summary>
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/// Constructor.
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/// </summary>
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public XPathNodeInfoTable() {
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this.hashTable = new XPathNodeInfoAtom[DefaultTableSize];
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this.sizeTable = 0;
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}
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/// <summary>
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/// Create a new XNodeInfoAtom and ensure it is atomized in the table.
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/// </summary>
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public XPathNodeInfoAtom Create(string localName, string namespaceUri, string prefix, string baseUri,
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XPathNode[] pageParent, XPathNode[] pageSibling, XPathNode[] pageSimilar,
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XPathDocument doc, int lineNumBase, int linePosBase) {
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XPathNodeInfoAtom info;
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// If this.infoCached already exists, then reuse it; else create new InfoAtom
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if (this.infoCached == null) {
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info = new XPathNodeInfoAtom(localName, namespaceUri, prefix, baseUri,
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pageParent, pageSibling, pageSimilar,
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doc, lineNumBase, linePosBase);
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}
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else {
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info = this.infoCached;
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this.infoCached = info.Next;
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info.Init(localName, namespaceUri, prefix, baseUri,
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pageParent, pageSibling, pageSimilar,
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doc, lineNumBase, linePosBase);
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}
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return Atomize(info);
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}
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/// <summary>
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/// Add a shared information item to the atomization table. If a matching item already exists, then that
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/// instance is returned. Otherwise, a new item is created. Thus, if itemX and itemY have both been added
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/// to the same InfoTable:
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/// 1. itemX.Equals(itemY) != true
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/// 2. (object) itemX != (object) itemY
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/// </summary>
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private XPathNodeInfoAtom Atomize(XPathNodeInfoAtom info) {
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XPathNodeInfoAtom infoNew, infoNext;
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// Search for existing XNodeInfoAtom in the table
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infoNew = this.hashTable[info.GetHashCode() & (this.hashTable.Length - 1)];
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while (infoNew != null) {
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if (info.Equals(infoNew)) {
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// Found existing atom, so return that. Reuse "info".
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info.Next = this.infoCached;
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this.infoCached = info;
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return infoNew;
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}
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infoNew = infoNew.Next;
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}
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// Expand table and rehash if necessary
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if (this.sizeTable >= this.hashTable.Length) {
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XPathNodeInfoAtom[] oldTable = this.hashTable;
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this.hashTable = new XPathNodeInfoAtom[oldTable.Length * 2];
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for (int i = 0; i < oldTable.Length; i++) {
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infoNew = oldTable[i];
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while (infoNew != null) {
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infoNext = infoNew.Next;
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AddInfo(infoNew);
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infoNew = infoNext;
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}
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}
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}
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// Can't find an existing XNodeInfoAtom, so use the one that was passed in
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AddInfo(info);
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return info;
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}
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/// <summary>
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/// Add a previously constructed InfoAtom to the table. If a collision occurs, then insert "info"
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/// as the head of a linked list.
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/// </summary>
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private void AddInfo(XPathNodeInfoAtom info) {
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int idx = info.GetHashCode() & (this.hashTable.Length - 1);
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info.Next = this.hashTable[idx];
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this.hashTable[idx] = info;
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this.sizeTable++;
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}
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/// <summary>
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/// Return InfoAtomTable formatted as a string.
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/// </summary>
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public override string ToString() {
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StringBuilder bldr = new StringBuilder();
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XPathNodeInfoAtom infoAtom;
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for (int i = 0; i < this.hashTable.Length; i++) {
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bldr.AppendFormat("{0,4}: ", i);
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infoAtom = this.hashTable[i];
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while (infoAtom != null) {
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if ((object) infoAtom != (object) this.hashTable[i])
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bldr.Append("\n ");
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bldr.Append(infoAtom);
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infoAtom = infoAtom.Next;
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}
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bldr.Append('\n');
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}
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return bldr.ToString();
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}
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}
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}
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