86 lines
3.4 KiB
C#
86 lines
3.4 KiB
C#
//-----------------------------------------------------------------------------
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//-----------------------------------------------------------------------------
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namespace System.Activities.XamlIntegration
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{
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using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Windows.Markup;
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using System.Xaml;
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public class SerializableFuncDeferringLoader : XamlDeferringLoader
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{
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const string xmlPrefix = "xml";
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public override object Load(XamlReader xamlReader, IServiceProvider context)
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{
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FuncFactory factory = FuncFactory.CreateFactory(xamlReader, context);
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IXamlNamespaceResolver nsResolver = context.GetService(typeof(IXamlNamespaceResolver)) as IXamlNamespaceResolver;
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if (nsResolver != null)
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{
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factory.ParentNamespaces = nsResolver.GetNamespacePrefixes().ToList();
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}
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return factory.GetFunc();
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}
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public override XamlReader Save(object value, IServiceProvider serviceProvider)
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{
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FuncFactory factory = GetFactory(value as Delegate);
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if (factory == null)
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{
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throw FxTrace.Exception.AsError(new InvalidOperationException(SR.SavingFuncToXamlNotSupported));
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}
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XamlReader result = factory.Nodes.GetReader();
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if (factory.ParentNamespaces != null)
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{
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result = InsertNamespaces(result, factory.ParentNamespaces);
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}
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return result;
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}
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static FuncFactory GetFactory(Delegate func)
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{
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return (func != null) ? func.Target as FuncFactory : null;
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}
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// We don't know what namespaces are actually used inside convertible values, so any namespaces
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// that were in the parent scope on load need to be regurgitated on save, unless the prefixes were
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// shadowed in the child scope.
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// This can potentially cause namespace bloat, but the alternative is emitting unloadable XAML.
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static XamlReader InsertNamespaces(XamlReader reader, IEnumerable<NamespaceDeclaration> parentNamespaces)
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{
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XamlNodeQueue namespaceNodes = new XamlNodeQueue(reader.SchemaContext);
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HashSet<string> childPrefixes = new HashSet<string>();
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while (reader.Read() && reader.NodeType == XamlNodeType.NamespaceDeclaration)
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{
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childPrefixes.Add(reader.Namespace.Prefix);
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namespaceNodes.Writer.WriteNode(reader);
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}
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foreach (NamespaceDeclaration parentNamespace in parentNamespaces)
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{
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if (!childPrefixes.Contains(parentNamespace.Prefix) &&
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!IsXmlNamespace(parentNamespace))
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{
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namespaceNodes.Writer.WriteNamespace(parentNamespace);
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}
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}
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if (!reader.IsEof)
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{
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namespaceNodes.Writer.WriteNode(reader);
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}
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return new ConcatenatingXamlReader(namespaceNodes.Reader, reader);
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}
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// We need to special-case the XML namespace because it is always in scope,
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// but can't actually be written to XML.
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static bool IsXmlNamespace(NamespaceDeclaration namespaceDecl)
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{
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return namespaceDecl.Prefix == xmlPrefix && namespaceDecl.Namespace == XamlLanguage.Xml1998Namespace;
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}
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}
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}
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