Added attached property support in bindings.

src/Markup/Perspex.Markup/Data/Parsers/ExpressionParser.cs

@@ -29,6 +29,10 @@ namespace Perspex.Markup.Data.Parsers
                     case State.BeforeMember:
                         state = ParseBeforeMember(r, nodes);
                         break;
+
+                    case State.AttachedProperty:
+                        state = ParseAttachedProperty(r, nodes);
+                        break;
                 }
             }
 
@@ -52,6 +56,10 @@ namespace Perspex.Markup.Data.Parsers
                 nodes.Add(new LogicalNotNode());
                 return State.Start;
             }
+            else if (ParseOpenBrace(r))
+            {
+                return State.AttachedProperty;
+            }
             else
             {
                 var identifier = IdentifierParser.Parse(r);
@@ -93,15 +101,42 @@ namespace Perspex.Markup.Data.Parsers
 
         private static State ParseBeforeMember(Reader r, IList<ExpressionNode> nodes)
         {
-            var identifier = IdentifierParser.Parse(r);
+            if (ParseOpenBrace(r))
+            {
+                return State.AttachedProperty;
+            }
+            else
+            {
+                var identifier = IdentifierParser.Parse(r);
+
+                if (identifier != null)
+                {
+                    nodes.Add(new PropertyAccessorNode(identifier));
+                    return State.AfterMember;
+                }
+
+                return State.End;
+            }
+        }
+
+        private static State ParseAttachedProperty(Reader r, List<ExpressionNode> nodes)
+        {
+            var owner = IdentifierParser.Parse(r);
 
-            if (identifier != null)
+            if (r.End || !r.TakeIf('.'))
             {
-                nodes.Add(new PropertyAccessorNode(identifier));
-                return State.AfterMember;
+                throw new ExpressionParseException(r.Position, "Invalid attached property name.");
             }
 
-            return State.End;
+            var name = IdentifierParser.Parse(r);
+
+            if (r.End || !r.TakeIf(')'))
+            {
+                throw new ExpressionParseException(r.Position, "Expected ')'.");
+            }
+
+            nodes.Add(new PropertyAccessorNode(owner + '.' + name));
+            return State.AfterMember;
         }
 
         private static bool ParseNot(Reader r)
@@ -114,11 +149,17 @@ namespace Perspex.Markup.Data.Parsers
             return !r.End && r.TakeIf('.');
         }
 
+        private static bool ParseOpenBrace(Reader r)
+        {
+            return !r.End && r.TakeIf('(');
+        }
+
         private enum State
         {
             Start,
             AfterMember,
             BeforeMember,
+            AttachedProperty,
             End,
         }
     }

tests/Perspex.Markup.UnitTests/Data/ExpressionObserverTests_AttachedProperty.cs

@@ -0,0 +1,147 @@
+// Copyright (c) The Perspex Project. All rights reserved.
+// Licensed under the MIT license. See licence.md file in the project root for full license information.
+
+using System;
+using System.Collections.Generic;
+using System.Reactive.Linq;
+using Perspex.Diagnostics;
+using Perspex.Markup.Data;
+using Xunit;
+
+namespace Perspex.Markup.UnitTests.Data
+{
+    public class ExpressionObserverTests_AttachedProperty
+    {
+        public ExpressionObserverTests_AttachedProperty()
+        {
+            var foo = Owner.FooProperty;
+        }
+
+        [Fact]
+        public async void Should_Get_Attached_Property_Value()
+        {
+            var data = new Class1();
+            var target = new ExpressionObserver(data, "(Owner.Foo)");
+            var result = await target.Take(1);
+
+            Assert.Equal("foo", result);
+
+            Assert.Null(((IPerspexObjectDebug)data).GetPropertyChangedSubscribers());
+        }
+
+        [Fact]
+        public async void Should_Get_Chained_Attached_Property_Value()
+        {
+            var data = new Class1
+            {
+                Next = new Class1
+                {
+                    [Owner.FooProperty] = "bar",
+                }
+            };
+
+            var target = new ExpressionObserver(data, "Next.(Owner.Foo)");
+            var result = await target.Take(1);
+
+            Assert.Equal("bar", result);
+
+            Assert.Null(((IPerspexObjectDebug)data).GetPropertyChangedSubscribers());
+        }
+
+        [Fact]
+        public void Should_Track_Simple_Attached_Value()
+        {
+            var data = new Class1();
+            var target = new ExpressionObserver(data, "(Owner.Foo)");
+            var result = new List<object>();
+
+            var sub = target.Subscribe(x => result.Add(x));
+            data.SetValue(Owner.FooProperty, "bar");
+
+            Assert.Equal(new[] { "foo", "bar" }, result);
+
+            sub.Dispose();
+
+            Assert.Null(((IPerspexObjectDebug)data).GetPropertyChangedSubscribers());
+        }
+
+        [Fact]
+        public void Should_Track_Chained_Attached_Value()
+        {
+            var data = new Class1
+            {
+                Next = new Class1
+                {
+                    [Owner.FooProperty] = "foo",
+                }
+            };
+
+            var target = new ExpressionObserver(data, "Next.(Owner.Foo)");
+            var result = new List<object>();
+
+            var sub = target.Subscribe(x => result.Add(x));
+            data.Next.SetValue(Owner.FooProperty, "bar");
+
+            Assert.Equal(new[] { "foo", "bar" }, result);
+
+            sub.Dispose();
+
+            Assert.Null(((IPerspexObjectDebug)data).GetPropertyChangedSubscribers());
+        }
+
+        [Fact]
+        public void Should_Not_Keep_Source_Alive()
+        {
+            Func<Tuple<ExpressionObserver, WeakReference>> run = () =>
+            {
+                var source = new Class1();
+                var target = new ExpressionObserver(source, "(Owner.Foo)");
+                return Tuple.Create(target, new WeakReference(source));
+            };
+
+            var result = run();
+            result.Item1.Subscribe(x => { });
+
+            GC.Collect();
+
+            Assert.Null(result.Item2.Target);
+        }
+
+        [Fact]
+        public void Should_Fail_With_Attached_Property_With_Only_1_Part()
+        {
+            var data = new Class1();
+
+            Assert.Throws<ExpressionParseException>(() => new ExpressionObserver(data, "(Owner)"));
+        }
+
+        [Fact]
+        public void Should_Fail_With_Attached_Property_With_More_Than_2_Parts()
+        {
+            var data = new Class1();
+
+            Assert.Throws<ExpressionParseException>(() => new ExpressionObserver(data, "(Owner.Foo.Bar)"));
+        }
+
+        private static class Owner
+        {
+            public static readonly AttachedProperty<string> FooProperty =
+                PerspexProperty.RegisterAttached<PerspexObject, string>(
+                    "Foo", 
+                    typeof(Owner), 
+                    defaultValue: "foo");
+        }
+
+        private class Class1 : PerspexObject
+        {
+            public static readonly StyledProperty<Class1> NextProperty =
+                PerspexProperty.Register<Class1, Class1>("Next");
+
+            public Class1 Next
+            {
+                get { return GetValue(NextProperty); }
+                set { SetValue(NextProperty, value); }
+            }
+        }
+    }
+}

tests/Perspex.Markup.UnitTests/Perspex.Markup.UnitTests.csproj

@@ -91,6 +91,7 @@
     <Compile Include="Data\ExpressionObserverTests_Indexer.cs" />
     <Compile Include="Data\ExpressionObserverTests_Negation.cs" />
     <Compile Include="Data\ExpressionObserverTests_Observable.cs" />
+    <Compile Include="Data\ExpressionObserverTests_AttachedProperty.cs" />
     <Compile Include="Data\ExpressionObserverTests_PerspexProperty.cs" />
     <Compile Include="Data\ExpressionObserverTests_Property.cs" />
     <Compile Include="Data\ExpressionObserverTests_SetValue.cs" />