From ebf4f90be427e3356e908596b5f2a9909dab6c8d Mon Sep 17 00:00:00 2001
From: Steven Kirk <grokys@users.noreply.github.com>
Date: Mon, 6 Apr 2020 23:34:03 +0200
Subject: [PATCH] Merge pull request #3678 from AvaloniaUI/fixes/2838-style-or

Fix XAML compiler handling of comma/or style selector.
---
 .../AvaloniaXamlIlSelectorTransformer.cs      | 40 ++++++++++--
 .../Xaml/StyleTests.cs                        | 62 +++++++++++++++++++
 2 files changed, 97 insertions(+), 5 deletions(-)

diff --git a/src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlSelectorTransformer.cs b/src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlSelectorTransformer.cs
index aac07f5b6e..d5114244cf 100644
--- a/src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlSelectorTransformer.cs
+++ b/src/Markup/Avalonia.Markup.Xaml/XamlIl/CompilerExtensions/Transformers/AvaloniaXamlIlSelectorTransformer.cs
@@ -104,6 +104,11 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
                     }
                 }
 
+                if (results != null && result != null)
+                {
+                    results.Add(result);
+                }
+
                 return results ?? result;
             }
 
@@ -158,9 +163,7 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
         protected void EmitCall(XamlIlEmitContext context, IXamlIlEmitter codeGen, Func<IXamlIlMethod, bool> method)
         {
             var selectors = context.Configuration.TypeSystem.GetType("Avalonia.Styling.Selectors");
-            var found = selectors.FindMethod(m => m.IsStatic && m.Parameters.Count > 0 &&
-                                      m.Parameters[0].FullName == "Avalonia.Styling.Selector"
-                                      && method(m));
+            var found = selectors.FindMethod(m => m.IsStatic && m.Parameters.Count > 0 && method(m));
             codeGen.EmitCall(found);
         }
     }
@@ -308,8 +311,35 @@ namespace Avalonia.Markup.Xaml.XamlIl.CompilerExtensions.Transformers
             _selectors.Add(node);
         }
         
-        //TODO: actually find the type
-        public override IXamlIlType TargetType => _selectors.FirstOrDefault()?.TargetType;
+        public override IXamlIlType TargetType
+        {
+            get
+            {
+                IXamlIlType result = null;
+
+                foreach (var selector in _selectors)
+                {
+                    if (selector.TargetType == null)
+                    {
+                        return null;
+                    }
+                    else if (result == null)
+                    {
+                        result = selector.TargetType;
+                    }
+                    else
+                    {
+                        while (!result.IsAssignableFrom(selector.TargetType))
+                        {
+                            result = result.BaseType;
+                        }
+                    }
+                }
+
+                return result;
+            }
+        }
+
         protected override void DoEmit(XamlIlEmitContext context, IXamlIlEmitter codeGen)
         {
             if (_selectors.Count == 0)
diff --git a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs
index f7629e5b9e..96a0789f3c 100644
--- a/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs
+++ b/tests/Avalonia.Markup.Xaml.UnitTests/Xaml/StyleTests.cs
@@ -278,5 +278,67 @@ namespace Avalonia.Markup.Xaml.UnitTests.Xaml
                 Assert.Equal(Colors.Red, ((ISolidColorBrush)notFoo.Background).Color);
             }
         }
+
+        [Fact]
+        public void Style_Can_Use_Or_Selector_1()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var xaml = @"
+<Window xmlns='https://github.com/avaloniaui'
+             xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <Window.Styles>
+        <Style Selector='Border.foo, Border.bar'>
+            <Setter Property='Background' Value='Red'/>
+        </Style>
+    </Window.Styles>
+    <StackPanel>
+        <Border Name='foo' Classes='foo'/>
+        <Border Name='bar' Classes='bar'/>
+        <Border Name='baz' Classes='baz'/>
+    </StackPanel>
+</Window>";
+                var loader = new AvaloniaXamlLoader();
+                var window = (Window)loader.Load(xaml);
+                var foo = window.FindControl<Border>("foo");
+                var bar = window.FindControl<Border>("bar");
+                var baz = window.FindControl<Border>("baz");
+
+                Assert.Equal(Brushes.Red, foo.Background);
+                Assert.Equal(Brushes.Red, bar.Background);
+                Assert.Null(baz.Background);
+            }
+        }
+
+        [Fact]
+        public void Style_Can_Use_Or_Selector_2()
+        {
+            using (UnitTestApplication.Start(TestServices.StyledWindow))
+            {
+                var xaml = @"
+<Window xmlns='https://github.com/avaloniaui'
+             xmlns:x='http://schemas.microsoft.com/winfx/2006/xaml'>
+    <Window.Styles>
+        <Style Selector='Button,Carousel,ListBox'>
+            <Setter Property='Background' Value='Red'/>
+        </Style>
+    </Window.Styles>
+    <StackPanel>
+        <Button Name='button'/>
+        <Carousel Name='carousel'/>
+        <ListBox Name='listBox'/>
+    </StackPanel>
+</Window>";
+                var loader = new AvaloniaXamlLoader();
+                var window = (Window)loader.Load(xaml);
+                var button = window.FindControl<Button>("button");
+                var carousel = window.FindControl<Carousel>("carousel");
+                var listBox = window.FindControl<ListBox>("listBox");
+
+                Assert.Equal(Brushes.Red, button.Background);
+                Assert.Equal(Brushes.Red, carousel.Background);
+                Assert.Equal(Brushes.Red, listBox.Background);
+            }
+        }
     }
 }