From a1126ab66bc9bd41cfa32dbefbe5758bcf5b4b32 Mon Sep 17 00:00:00 2001
From: Stephane Delcroix <stephane@delcroix.org>
Date: Mon, 15 Aug 2016 22:18:26 +0200
Subject: [Xaml] Simplify listnodes with single elements (#304)

---
 Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs | 14 +++++++++++---
 Xamarin.Forms.Xaml.UnitTests/SetValue.xaml        |  9 +++++++++
 Xamarin.Forms.Xaml.UnitTests/SetValue.xaml.cs     |  8 ++++++++
 Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs      | 18 +++++++++++++-----
 Xamarin.Forms.Xaml/XmlName.cs                     |  1 +
 5 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs b/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs
index b6bdf40b..5e11fe1d 100644
--- a/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs
+++ b/Xamarin.Forms.Build.Tasks/SetPropertiesVisitor.cs
@@ -79,6 +79,15 @@ namespace Xamarin.Forms.Build.Tasks
 
 		public void Visit(ElementNode node, INode parentNode)
 		{
+			XmlName propertyName = XmlName.Empty;
+
+			//Simplify ListNodes with single elements
+			var pList = parentNode as ListNode;
+			if (pList != null && pList.CollectionItems.Count == 1) {
+				propertyName = pList.XmlName;
+				parentNode = parentNode.Parent;
+			}
+
 			//if this node is an IMarkupExtension, invoke ProvideValue() and replace the variable
 			var vardef = Context.Variables[node];
 			var vardefref = new VariableDefinitionReference(vardef);
@@ -90,8 +99,7 @@ namespace Xamarin.Forms.Build.Tasks
 				Context.Variables[node] = vardef;
 			}
 
-			XmlName propertyName;
-			if (TryGetPropertyName(node, parentNode, out propertyName))
+			if (propertyName != XmlName.Empty || TryGetPropertyName(node, parentNode, out propertyName))
 			{
 				if (skips.Contains(propertyName))
 					return;
@@ -675,4 +683,4 @@ namespace Xamarin.Forms.Build.Tasks
 			return vardefref.VariableDefinition;
 		}
 	}
-}
\ No newline at end of file
+}
diff --git a/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml b/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml
index 133e0e9b..da844ed0 100644
--- a/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml
+++ b/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml
@@ -3,6 +3,9 @@
 	xmlns="http://xamarin.com/schemas/2014/forms"
 	xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
 	xmlns:local="clr-namespace:Xamarin.Forms.Xaml.UnitTests"
+	xmlns:d="ignoreme"
+	xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+	mc:Ignorable="d"
 	x:Class="Xamarin.Forms.Xaml.UnitTests.SetValue">
 	<ContentPage.Resources>
 		<ResourceDictionary>
@@ -74,5 +77,11 @@
 		<StackLayout x:Name="stack4">
 			<local:ConvertibleToView/>
 		</StackLayout>
+		<ContentView x:Name="contentview2">
+			<ContentView.Content>
+				<Label />
+				<d:IgnorableElement />
+			</ContentView.Content>
+		</ContentView>
 	</StackLayout>
 </ContentPage>
\ No newline at end of file
diff --git a/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml.cs b/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml.cs
index ce377a71..2226402c 100644
--- a/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml.cs
+++ b/Xamarin.Forms.Xaml.UnitTests/SetValue.xaml.cs
@@ -207,6 +207,14 @@ namespace Xamarin.Forms.Xaml.UnitTests
 				var page = new SetValue(useCompiledXaml);
 				Assert.That(page.stack4.Children[0], Is.TypeOf<Button>());
 			}
+
+			[TestCase(false)]
+			[TestCase(true)]
+			public void ListsAreSimplified(bool useCompiledXaml)
+			{
+				var page = new SetValue(useCompiledXaml);
+				Assert.That(page.contentview2.Content, Is.TypeOf<Label>());
+			}
 		}
 	}
 }
\ No newline at end of file
diff --git a/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs b/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs
index 1e332323..108d707e 100644
--- a/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs
+++ b/Xamarin.Forms.Xaml/ApplyPropertiesVisitor.cs
@@ -102,21 +102,29 @@ namespace Xamarin.Forms.Xaml
 				value = valueProvider.ProvideValue(serviceProvider);
 			}
 
-			XmlName propertyName;
-			if (TryGetPropertyName(node, parentNode, out propertyName))
-			{
+			XmlName propertyName = XmlName.Empty;
+
+			//Simplify ListNodes with single elements
+			var pList = parentNode as ListNode;
+			if (pList != null && pList.CollectionItems.Count == 1) {
+				propertyName = pList.XmlName;
+				parentNode = parentNode.Parent;
+				parentElement = parentNode as IElementNode;
+			}
+
+			if (propertyName != XmlName.Empty || TryGetPropertyName(node, parentNode, out propertyName)) {
 				if (Skips.Contains(propertyName))
 					return;
 				if (parentElement.SkipProperties.Contains(propertyName))
 					return;
 
-				var source = Values[parentNode];
+				var source = Values [parentNode];
 
 				if (propertyName == XmlName._CreateContent && source is ElementTemplate)
 					SetTemplate(source as ElementTemplate, node);
 				else
 					SetPropertyValue(source, propertyName, value, Context.RootElement, node, Context, node);
-			}
+			} 
 			else if (IsCollectionItem(node, parentNode) && parentNode is IElementNode)
 			{
 				// Collection element, implicit content, or implicit collection element.
diff --git a/Xamarin.Forms.Xaml/XmlName.cs b/Xamarin.Forms.Xaml/XmlName.cs
index e22a162d..09cf3bca 100644
--- a/Xamarin.Forms.Xaml/XmlName.cs
+++ b/Xamarin.Forms.Xaml/XmlName.cs
@@ -11,6 +11,7 @@ namespace Xamarin.Forms.Xaml
 		public static readonly XmlName xTypeArguments = new XmlName("x", "TypeArguments");
 		public static readonly XmlName xArguments = new XmlName("x", "Arguments");
 		public static readonly XmlName xFactoryMethod = new XmlName("x", "xFactoryMethod");
+		public static readonly XmlName Empty = new XmlName();
 
 		public string NamespaceURI { get; }
 
-- 
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