[Xaml] Clone node tree on DT, allow markup to be evaluated multiple times (#295)

2 files changed, 51 insertions, 7 deletions

diff --git a/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs b/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs
index 108d707e..327a4122 100644
--- a/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs
+++ b/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs
@@ -433,14 +433,16 @@ namespace Xamarin.Forms.Xaml
 			((IDataTemplate)dt).LoadTemplate = () =>
 			{
 #pragma warning restore 0612
+				var cnode = node.Clone();
 				var context = new HydratationContext { ParentContext = Context, RootElement = Context.RootElement };
-				node.Accept(new ExpandMarkupsVisitor(context), null);
-				node.Accept(new NamescopingVisitor(context), null);
-				node.Accept(new CreateValuesVisitor(context), null);
-				node.Accept(new RegisterXNamesVisitor(context), null);
-				node.Accept(new FillResourceDictionariesVisitor(context), null);
-				node.Accept(new ApplyPropertiesVisitor(context, true), null);
-				return context.Values[node];
+				cnode.Accept(new XamlNodeVisitor((n, parent) => n.Parent = parent), node.Parent); //set parents for {StaticResource}
+				cnode.Accept(new ExpandMarkupsVisitor(context), null);
+				cnode.Accept(new NamescopingVisitor(context), null);
+				cnode.Accept(new CreateValuesVisitor(context), null);
+				cnode.Accept(new RegisterXNamesVisitor(context), null);
+				cnode.Accept(new FillResourceDictionariesVisitor(context), null);
+				cnode.Accept(new ApplyPropertiesVisitor(context, true), null);
+				return context.Values[cnode];
 			};
 		}
 	}
diff --git a/Xamarin.Forms.Xaml/XamlNode.cs b/Xamarin.Forms.Xaml/XamlNode.cs
index 6d84c67d..f794428b 100644
--- a/Xamarin.Forms.Xaml/XamlNode.cs
+++ b/Xamarin.Forms.Xaml/XamlNode.cs
@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;
@@ -15,6 +16,7 @@ namespace Xamarin.Forms.Xaml
 		INode Parent { get; set; }
 
 		void Accept(IXamlNodeVisitor visitor, INode parentNode);
+		INode Clone();
 	}
 
 	internal interface IValueNode : INode
@@ -81,6 +83,8 @@ namespace Xamarin.Forms.Xaml
 		public int LineNumber { get; set; }
 
 		public int LinePosition { get; set; }
+
+		public abstract INode Clone();
 	}
 
 	[DebuggerDisplay("{Value}")]
@@ -98,6 +102,13 @@ namespace Xamarin.Forms.Xaml
 		{
 			visitor.Visit(this, parentNode);
 		}
+
+		public override INode Clone()
+		{
+			return new ValueNode(Value, NamespaceResolver, LineNumber, LinePosition) {
+				IgnorablePrefixes = IgnorablePrefixes
+			};
+		}
 	}
 
 	[DebuggerDisplay("{MarkupString}")]
@@ -116,6 +127,13 @@ namespace Xamarin.Forms.Xaml
 		{
 			visitor.Visit(this, parentNode);
 		}
+
+		public override INode Clone()
+		{
+			return new MarkupNode(MarkupString, NamespaceResolver, LineNumber, LinePosition) {
+				IgnorablePrefixes = IgnorablePrefixes
+			};
+		}
 	}
 
 	internal class ElementNode : BaseNode, IValueNode, IElementNode
@@ -174,6 +192,20 @@ namespace Xamarin.Forms.Xaml
 			var enode = node as ElementNode;
 			return enode.XmlType.Name == "ResourceDictionary";
 		}
+
+		public override INode Clone()
+		{
+			var clone = new ElementNode(XmlType, NamespaceURI, NamespaceResolver, LineNumber, LinePosition) {
+				IgnorablePrefixes = IgnorablePrefixes
+			};
+			foreach (var kvp in Properties)
+				clone.Properties.Add(kvp.Key, kvp.Value.Clone());
+			foreach (var p in SkipProperties)
+				clone.SkipProperties.Add(p);
+			foreach (var p in CollectionItems)
+				clone.CollectionItems.Add(p.Clone());
+			return clone;
+		}
 	}
 
 	internal abstract class RootNode : ElementNode
@@ -220,6 +252,16 @@ namespace Xamarin.Forms.Xaml
 			if (visitor.VisitChildrenFirst)
 				visitor.Visit(this, parentNode);
 		}
+
+		public override INode Clone()
+		{
+			var items = new List<INode>();
+			foreach (var p in CollectionItems)
+				items.Add(p.Clone());
+			return new ListNode(items, NamespaceResolver, LineNumber, LinePosition) {
+				IgnorablePrefixes = IgnorablePrefixes
+			};
+		}
 	}
 
 	internal static class INodeExtensions