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//------------------------------------------------------------------------------
// <copyright file="XmlAutoDetectWriter.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">Microsoft</owner>
//------------------------------------------------------------------------------
namespace System.Xml {
using System;
using System.Diagnostics;
using System.IO;
using System.Text;
using System.Xml;
using System.Xml.Schema;
/// <summary>
/// This writer implements XmlOutputMethod.AutoDetect. If the first element is "html", then output will be
/// directed to an Html writer. Otherwise, output will be directed to an Xml writer.
/// </summary>
internal class XmlAutoDetectWriter : XmlRawWriter, IRemovableWriter {
private XmlRawWriter wrapped;
private OnRemoveWriter onRemove;
private XmlWriterSettings writerSettings;
private XmlEventCache eventCache; // Cache up events until first StartElement is encountered
private TextWriter textWriter;
private Stream strm;
//-----------------------------------------------
// Constructors
//-----------------------------------------------
private XmlAutoDetectWriter(XmlWriterSettings writerSettings) {
Debug.Assert(writerSettings.OutputMethod == XmlOutputMethod.AutoDetect);
this.writerSettings = (XmlWriterSettings)writerSettings.Clone();
this.writerSettings.ReadOnly = true;
// Start caching all events
this.eventCache = new XmlEventCache(string.Empty, true);
}
public XmlAutoDetectWriter(TextWriter textWriter, XmlWriterSettings writerSettings)
: this(writerSettings) {
this.textWriter = textWriter;
}
public XmlAutoDetectWriter(Stream strm, XmlWriterSettings writerSettings)
: this(writerSettings) {
this.strm = strm;
}
//-----------------------------------------------
// IRemovableWriter interface
//-----------------------------------------------
/// <summary>
/// This writer will raise this event once it has determined whether to replace itself with the Html or Xml writer.
/// </summary>
public OnRemoveWriter OnRemoveWriterEvent {
get { return this.onRemove; }
set { this.onRemove = value; }
}
//-----------------------------------------------
// XmlWriter interface
//-----------------------------------------------
public override XmlWriterSettings Settings {
get { return this.writerSettings; }
}
public override void WriteDocType(string name, string pubid, string sysid, string subset) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteDocType(name, pubid, sysid, subset);
}
public override void WriteStartElement(string prefix, string localName, string ns) {
if (this.wrapped == null) {
// This is the first time WriteStartElement has been called, so create the Xml or Html writer
if (ns.Length == 0 && IsHtmlTag(localName))
CreateWrappedWriter(XmlOutputMethod.Html);
else
CreateWrappedWriter(XmlOutputMethod.Xml);
}
this.wrapped.WriteStartElement(prefix, localName, ns);
}
public override void WriteStartAttribute(string prefix, string localName, string ns) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteStartAttribute(prefix, localName, ns);
}
public override void WriteEndAttribute() {
Debug.Assert(this.wrapped != null);
this.wrapped.WriteEndAttribute();
}
public override void WriteCData(string text) {
if (TextBlockCreatesWriter(text))
this.wrapped.WriteCData(text);
else
this.eventCache.WriteCData(text);
}
public override void WriteComment(string text) {
if (this.wrapped == null)
this.eventCache.WriteComment(text);
else
this.wrapped.WriteComment(text);
}
public override void WriteProcessingInstruction(string name, string text) {
if (this.wrapped == null)
this.eventCache.WriteProcessingInstruction(name, text);
else
this.wrapped.WriteProcessingInstruction(name, text);
}
public override void WriteWhitespace(string ws) {
if (this.wrapped == null)
this.eventCache.WriteWhitespace(ws);
else
this.wrapped.WriteWhitespace(ws);
}
public override void WriteString(string text) {
if (TextBlockCreatesWriter(text))
this.wrapped.WriteString(text);
else
this.eventCache.WriteString(text);
}
public override void WriteChars(char[] buffer, int index, int count) {
WriteString(new string(buffer, index, count));
}
public override void WriteRaw(char[] buffer, int index, int count) {
WriteRaw(new string(buffer, index, count));
}
public override void WriteRaw(string data) {
if (TextBlockCreatesWriter(data))
this.wrapped.WriteRaw(data);
else
this.eventCache.WriteRaw(data);
}
public override void WriteEntityRef(string name) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteEntityRef(name);
}
public override void WriteCharEntity(char ch) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteCharEntity(ch);
}
public override void WriteSurrogateCharEntity(char lowChar, char highChar) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteSurrogateCharEntity(lowChar, highChar);
}
public override void WriteBase64(byte[] buffer, int index, int count) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteBase64(buffer, index, count);
}
public override void WriteBinHex(byte[] buffer, int index, int count) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteBinHex(buffer, index, count);
}
public override void Close() {
// Flush any cached events to an Xml writer
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.Close();
}
public override void Flush() {
// Flush any cached events to an Xml writer
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.Flush();
}
public override void WriteValue(object value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(string value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(bool value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(DateTime value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(DateTimeOffset value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(double value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(float value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(decimal value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(int value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
public override void WriteValue(long value) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteValue(value);
}
//-----------------------------------------------
// XmlRawWriter interface
//-----------------------------------------------
internal override IXmlNamespaceResolver NamespaceResolver {
get {
return this.resolver;
}
set {
this.resolver = value;
if (this.wrapped == null)
this.eventCache.NamespaceResolver = value;
else
this.wrapped.NamespaceResolver = value;
}
}
internal override void WriteXmlDeclaration(XmlStandalone standalone) {
// Forces xml writer to be created
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteXmlDeclaration(standalone);
}
internal override void WriteXmlDeclaration(string xmldecl) {
// Forces xml writer to be created
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteXmlDeclaration(xmldecl);
}
internal override void StartElementContent() {
Debug.Assert(this.wrapped != null);
this.wrapped.StartElementContent();
}
internal override void WriteEndElement(string prefix, string localName, string ns) {
Debug.Assert(this.wrapped != null);
this.wrapped.WriteEndElement(prefix, localName, ns);
}
internal override void WriteFullEndElement(string prefix, string localName, string ns) {
Debug.Assert(this.wrapped != null);
this.wrapped.WriteFullEndElement(prefix, localName, ns);
}
internal override void WriteNamespaceDeclaration(string prefix, string ns) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteNamespaceDeclaration(prefix, ns);
}
internal override bool SupportsNamespaceDeclarationInChunks {
get {
return this.wrapped.SupportsNamespaceDeclarationInChunks;
}
}
internal override void WriteStartNamespaceDeclaration( string prefix ) {
EnsureWrappedWriter(XmlOutputMethod.Xml);
this.wrapped.WriteStartNamespaceDeclaration(prefix);
}
internal override void WriteEndNamespaceDeclaration() {
this.wrapped.WriteEndNamespaceDeclaration();
}
//-----------------------------------------------
// Helper methods
//-----------------------------------------------
/// <summary>
/// Return true if "tagName" == "html" (case-insensitive).
/// </summary>
private static bool IsHtmlTag(string tagName) {
if (tagName.Length != 4)
return false;
if (tagName[0] != 'H' && tagName[0] != 'h')
return false;
if (tagName[1] != 'T' && tagName[1] != 't')
return false;
if (tagName[2] != 'M' && tagName[2] != 'm')
return false;
if (tagName[3] != 'L' && tagName[3] != 'l')
return false;
return true;
}
/// <summary>
/// If a wrapped writer has not yet been created, create one.
/// </summary>
private void EnsureWrappedWriter(XmlOutputMethod outMethod) {
if (this.wrapped == null)
CreateWrappedWriter(outMethod);
}
/// <summary>
/// If the specified text consist only of whitespace, then cache the whitespace, as it is not enough to
/// force the creation of a wrapped writer. Otherwise, create a wrapped writer if one has not yet been
/// created and return true.
/// </summary>
private bool TextBlockCreatesWriter(string textBlock) {
if (this.wrapped == null) {
// Whitespace-only text blocks aren't enough to determine Xml vs. Html
if (XmlCharType.Instance.IsOnlyWhitespace(textBlock)) {
return false;
}
// Non-whitespace text block selects Xml method
CreateWrappedWriter(XmlOutputMethod.Xml);
}
return true;
}
/// <summary>
/// Create either the Html or Xml writer and send any cached events to it.
/// </summary>
private void CreateWrappedWriter(XmlOutputMethod outMethod) {
Debug.Assert(this.wrapped == null);
// Create either the Xml or Html writer
this.writerSettings.ReadOnly = false;
this.writerSettings.OutputMethod = outMethod;
// If Indent was not set by the user, then default to True for Html
if (outMethod == XmlOutputMethod.Html && this.writerSettings.IndentInternal == TriState.Unknown)
this.writerSettings.Indent = true;
this.writerSettings.ReadOnly = true;
if (textWriter != null)
this.wrapped = ((XmlWellFormedWriter)XmlWriter.Create(this.textWriter, this.writerSettings)).RawWriter;
else
this.wrapped = ((XmlWellFormedWriter)XmlWriter.Create(this.strm, this.writerSettings)).RawWriter;
// Send cached events to the new writer
this.eventCache.EndEvents();
this.eventCache.EventsToWriter(this.wrapped);
// Send OnRemoveWriter event
if (this.onRemove != null)
(this.onRemove)(this.wrapped);
}
}
}
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