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// Copyright (c) AlphaSierraPapa for the SharpDevelop Team (for details please see \doc\copyright.txt)
// This code is distributed under the GNU LGPL (for details please see \doc\license.txt)
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Globalization;
using System.Linq;
using System.Threading;
using Tango.Scripting.Editors.Document;
namespace Tango.Scripting.Editors.Xml
{
/// <summary>
/// Creates object tree from XML document.
/// </summary>
/// <remarks>
/// The created tree fully describes the document and thus the orginal XML file can be
/// exactly reproduced.
///
/// Any further parses will reparse only the changed parts and the existing tree will
/// be updated with the changes. The user can add event handlers to be notified of
/// the changes. The parser tries to minimize the number of changes to the tree.
/// (for example, it will add a single child at the start of collection rather than
/// clearing the collection and adding new children)
///
/// The object tree consists of following types:
/// RawObject - Abstact base class for all types
/// RawContainer - Abstact base class for all types that can contain child nodes
/// RawDocument - The root object of the XML document
/// RawElement - Logical grouping of other nodes together. The first child is always the start tag.
/// RawTag - Represents any markup starting with "<" and (hopefully) ending with ">"
/// RawAttribute - Name-value pair in a tag
/// RawText - Whitespace or character data
///
/// For example, see the following XML and the produced object tree:
/// <![CDATA[
/// <!-- My favourite quote -->
/// <quote author="Albert Einstein">
/// Make everything as simple as possible, but not simpler.
/// </quote>
///
/// RawDocument
/// RawTag "<!--" "-->"
/// RawText " My favourite quote "
/// RawElement
/// RawTag "<" "quote" ">"
/// RawText " "
/// RawAttribute 'author="Albert Einstein"'
/// RawText "\n Make everything as simple as possible, but not simpler.\n"
/// RawTag "</" "quote" ">"
/// ]]>
///
/// The precise content of RawTag depends on what it represents:
/// <![CDATA[
/// Start tag: "<" Name? (RawText+ RawAttribute)* RawText* (">" | "/>")
/// End tag: "</" Name? (RawText+ RawAttribute)* RawText* ">"
/// P.instr.: "<?" Name? (RawText)* "?>"
/// Comment: "<!--" (RawText)* "-->"
/// CData: "<![CDATA[" (RawText)* "]]" ">"
/// DTD: "<!DOCTYPE" (RawText+ RawTag)* RawText* ">" (DOCTYPE or other DTD names)
/// UknownBang: "<!" (RawText)* ">"
/// ]]>
///
/// The type of tag can be identified by the opening backet.
/// There are helpper properties in the RawTag class to identify the type, exactly
/// one of the properties will be true.
///
/// The closing bracket may be missing or may be different for mallformed XML.
///
/// Note that there can always be multiple consequtive RawText nodes.
/// This is to ensure that idividual texts are not too long.
///
/// XML Spec: http://www.w3.org/TR/xml/
/// XML EBNF: http://www.jelks.nu/XML/xmlebnf.html
///
/// Internals:
///
/// "Try" methods can silently fail by returning false.
/// MoveTo methods do not move if they are already at the given target
/// If methods return some object, it must be no-empty. It is up to the caller to ensure
/// the context is appropriate for reading.
///
/// </remarks>
public class AXmlParser
{
AXmlDocument userDocument;
internal TrackedSegmentCollection TrackedSegments { get; private set; }
/// <summary>
/// Generate syntax error when seeing enity reference other then the build-in ones
/// </summary>
public bool UnknownEntityReferenceIsError { get; set; }
/// <summary> Create new parser </summary>
public AXmlParser()
{
this.Lock = new ReaderWriterLockSlim(LockRecursionPolicy.SupportsRecursion);
ClearInternal();
}
/// <summary> Throws exception if condition is false </summary>
internal static void Assert(bool condition, string message)
{
if (!condition) {
throw new InternalException("Assertion failed: " + message);
}
}
/// <summary> Throws exception if condition is false </summary>
[Conditional("DEBUG")]
internal static void DebugAssert(bool condition, string message)
{
if (!condition) {
throw new InternalException("Assertion failed: " + message);
}
}
[Conditional("DEBUG")]
internal static void Log(string text, params object[] pars)
{
//System.Diagnostics.Debug.WriteLine(string.Format(CultureInfo.InvariantCulture, "XML: " + text, pars));
}
/// <summary>
/// Incrementaly parse the given text.
/// You have to hold the write lock.
/// </summary>
/// <param name="input">
/// The full XML text of the new document.
/// </param>
/// <param name="changesSinceLastParse">
/// Changes since last parse. Null will cause full reparse.
/// </param>
public AXmlDocument Parse(string input, IEnumerable<DocumentChangeEventArgs> changesSinceLastParse)
{
if (!Lock.IsWriteLockHeld)
throw new InvalidOperationException("Lock needed!");
// Use changes to invalidate cache
if (changesSinceLastParse != null) {
this.TrackedSegments.UpdateOffsetsAndInvalidate(changesSinceLastParse);
} else {
this.TrackedSegments.InvalidateAll();
}
TagReader tagReader = new TagReader(this, input);
List<AXmlObject> tags = tagReader.ReadAllTags();
AXmlDocument parsedDocument = new TagMatchingHeuristics(this, input, tags).ReadDocument();
tagReader.PrintStringCacheStats();
AXmlParser.Log("Updating main DOM tree...");
userDocument.UpdateTreeFrom(parsedDocument);
userDocument.DebugCheckConsistency(true);
Assert(userDocument.GetSelfAndAllChildren().Count() == parsedDocument.GetSelfAndAllChildren().Count(), "Parsed document and updated document have different number of children");
return userDocument;
}
/// <summary>
/// Makes calls to Parse() thread-safe. Use Lock everywhere Parse() is called.
/// </summary>
public ReaderWriterLockSlim Lock { get; private set; }
/// <summary>
/// Returns the last cached version of the document.
/// </summary>
/// <exception cref="InvalidOperationException">No read lock is held by the current thread.</exception>
public AXmlDocument LastDocument {
get {
if (!Lock.IsReadLockHeld)
throw new InvalidOperationException("Read lock needed!");
return userDocument;
}
}
/// <summary>
/// Clears the parser data.
/// </summary>
/// <exception cref="InvalidOperationException">No write lock is held by the current thread.</exception>
public void Clear()
{
if (!Lock.IsWriteLockHeld)
throw new InvalidOperationException("Write lock needed!");
ClearInternal();
}
void ClearInternal()
{
this.UnknownEntityReferenceIsError = true;
this.TrackedSegments = new TrackedSegmentCollection();
this.userDocument = new AXmlDocument() { Parser = this };
this.userDocument.Document = this.userDocument;
// Track the document
this.TrackedSegments.AddParsedObject(this.userDocument, null);
this.userDocument.IsCached = false;
}
}
}
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