Add new Queue and Stack APIs

src/System.Collections/pkg/System.Collections.pkgproj

@@ -2,7 +2,7 @@
 <Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
   <ItemGroup>
-    <ProjectReference Include="..\ref\System.Collections.csproj">
+    <ProjectReference Include="..\ref\System.Collections.builds">
       <SupportedFramework>netcoreapp1.1;net463;$(AllXamarinFrameworks)</SupportedFramework>
     </ProjectReference>
     <ProjectReference Include="..\src\System.Collections.csproj">

src/System.Collections/ref/System.Collections.builds

@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="utf-8"?>
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.props))\dir.props" />
+  <ItemGroup>
+    <Project Include="System.Collections.csproj" />
+    <Project Include="System.Collections.csproj">
+      <TargetGroup>netcoreapp1.1</TargetGroup>
+    </Project>
+  </ItemGroup>
+  <Import Project="$([MSBuild]::GetDirectoryNameOfFileAbove($(MSBuildThisFileDirectory), dir.traversal.targets))\dir.traversal.targets" />
+</Project>

src/System.Collections/ref/System.Collections.cs

@@ -367,6 +367,10 @@ void System.Collections.ICollection.CopyTo(System.Array array, int index) { }
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return default(System.Collections.IEnumerator); }
         public T[] ToArray() { return default(T[]); }
         public void TrimExcess() { }
+#if netcoreapp11
+        public bool TryDequeue(out T result) { result = default(T); return default(bool); }
+        public bool TryPeek(out T result) { result = default(T); return default(bool); }
+#endif
         [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
         public partial struct Enumerator : System.Collections.Generic.IEnumerator<T>, System.Collections.IEnumerator, System.IDisposable
         {
@@ -609,6 +613,10 @@ void System.Collections.ICollection.CopyTo(System.Array array, int arrayIndex) {
         System.Collections.IEnumerator System.Collections.IEnumerable.GetEnumerator() { return default(System.Collections.IEnumerator); }
         public T[] ToArray() { return default(T[]); }
         public void TrimExcess() { }
+#if netcoreapp11
+        public bool TryPeek(out T result) { result = default(T); return default(bool); }
+        public bool TryPop(out T result) { result = default(T); return default(bool); }
+#endif
         [System.Runtime.InteropServices.StructLayoutAttribute(System.Runtime.InteropServices.LayoutKind.Sequential)]
         public partial struct Enumerator : System.Collections.Generic.IEnumerator<T>, System.Collections.IEnumerator, System.IDisposable
         {

src/System.Collections/ref/System.Collections.csproj

@@ -4,7 +4,8 @@
   <PropertyGroup>
     <AssemblyVersion>4.1.0.0</AssemblyVersion>
     <OutputType>Library</OutputType>
-    <NuGetTargetMoniker>.NETStandard,Version=v1.7</NuGetTargetMoniker>
+    <NuGetTargetMoniker Condition="'$(TargetGroup)' == ''">.NETStandard,Version=v1.7</NuGetTargetMoniker>
+    <DefineConstants Condition="'$(TargetGroup)' == 'netcoreapp1.1'">$(DefineConstants);netcoreapp11</DefineConstants>
   </PropertyGroup>
   <ItemGroup>
     <Compile Include="System.Collections.cs" />

src/System.Collections/ref/project.json

@@ -3,10 +3,7 @@
     "System.Runtime": "4.3.0-beta-24522-03"
   },
   "frameworks": {
-    "netstandard1.7": {
-      "imports": [
-        "dotnet5.8"
-      ]
-    }
+    "netstandard1.7": {},
+    "netcoreapp1.1": {}
   }
 }

src/System.Collections/src/System.Collections.csproj

@@ -15,7 +15,9 @@
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'net463_Release|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard1.7_Debug|AnyCPU'" />
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netstandard1.7_Release|AnyCPU'" />
-  <ItemGroup Condition="'$(TargetGroup)' == '' OR '$(TargetGroup)'=='netstandard1.7'">
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp1.1_Debug|AnyCPU'" />
+  <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'netcoreapp1.1_Release|AnyCPU'" />
+  <ItemGroup Condition="'$(TargetGroup)' == '' OR '$(TargetGroup)'=='netstandard1.7' OR '$(TargetGroup)'=='netcoreapp1.1'">
     <ProjectReference Include="..\..\System.Runtime\src\System.Runtime.csproj">
       <TargetGroup>netstandard1.7</TargetGroup>
     </ProjectReference>

src/System.Collections/src/System/Collections/Generic/Queue.cs

@@ -238,6 +238,22 @@ public T Dequeue()
             return removed;
         }
 
+        public bool TryDequeue(out T result)
+        {
+            if (_size == 0)
+            {
+            	result = default(T);
+            	return false;
+            }
+
+            result = _array[_head];
+            _array[_head] = default(T);
+            MoveNext(ref _head);
+            _size--;
+            _version++;
+            return true;
+        }
+
         // Returns the object at the head of the queue. The object remains in the
         // queue. If the queue is empty, this method throws an 
         // InvalidOperationException.
@@ -249,6 +265,18 @@ public T Peek()
             return _array[_head];
         }
 
+        public bool TryPeek(out T result)
+        {
+            if (_size == 0)
+            {
+            	result = default(T);
+            	return false;
+            }
+
+            result = _array[_head];
+            return true;
+        }
+
         // Returns true if the queue contains at least one object equal to item.
         // Equality is determined using item.Equals().
         public bool Contains(T item)

src/System.Collections/src/System/Collections/Generic/Stack.cs

@@ -200,6 +200,17 @@ public T Peek()
             return _array[_size - 1];
         }
 
+        public bool TryPeek(out T result)
+        {
+            if (_size == 0)
+            {
+                result = default(T);
+                return false;
+            }
+            result = _array[_size - 1];
+            return true;
+        }
+
         // Pops an item from the top of the stack.  If the stack is empty, Pop
         // throws an InvalidOperationException.
         public T Pop()
@@ -212,6 +223,20 @@ public T Pop()
             return item;
         }
 
+        public bool TryPop(out T result)
+        {
+            if (_size == 0)
+            {
+                result = default(T);
+                return false;
+            }
+
+            _version++;
+            result = _array[--_size];
+            _array[_size] = default(T);     // Free memory quicker.
+            return true;
+        }
+
         // Pushes an item to the top of the stack.
         public void Push(T item)
         {

src/System.Collections/tests/Generic/Queue/Queue.Generic.Tests.cs

@@ -11,7 +11,7 @@ namespace System.Collections.Tests
     /// <summary>
     /// Contains tests that ensure the correctness of the Queue class.
     /// </summary>
-    public abstract class Queue_Generic_Tests<T> : IGenericSharedAPI_Tests<T>
+    public abstract partial class Queue_Generic_Tests<T> : IGenericSharedAPI_Tests<T>
     {
         #region Queue<T> Helper Methods
 

src/System.Collections/tests/Generic/Queue/Queue.Generic.Tests.netcoreapp1.1.cs

@@ -0,0 +1,59 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace System.Collections.Tests
+{
+    public abstract partial class Queue_Generic_Tests<T> : IGenericSharedAPI_Tests<T>
+    {
+        [Theory]
+        [MemberData(nameof(ValidCollectionSizes))]
+        public void Queue_Generic_TryDequeue_AllElements(int count)
+        {
+            Queue<T> queue = GenericQueueFactory(count);
+            List<T> elements = queue.ToList();
+            foreach (T element in elements)
+            {
+                T result;
+                Assert.True(queue.TryDequeue(out result));
+                Assert.Equal(element, result);
+            }
+        }
+
+        [Fact]
+        public void Queue_Generic_TryDequeue_EmptyQueue_ReturnsFalse()
+        {
+            T result;
+            Assert.False(new Queue<T>().TryDequeue(out result));
+            Assert.Equal(default(T), result);
+        }
+
+        [Theory]
+        [MemberData(nameof(ValidCollectionSizes))]
+        public void Queue_Generic_TryPeek_AllElements(int count)
+        {
+            Queue<T> queue = GenericQueueFactory(count);
+            List<T> elements = queue.ToList();
+            foreach (T element in elements)
+            {
+                T result;
+                Assert.True(queue.TryPeek(out result));
+                Assert.Equal(element, result);
+
+                queue.Dequeue();
+            }
+        }
+
+        [Fact]
+        public void Queue_Generic_TryPeek_EmptyQueue_ReturnsFalse()
+        {
+            T result;
+            Assert.False(new Queue<T>().TryPeek(out result));
+            Assert.Equal(default(T), result);
+        }
+    }
+}

src/System.Collections/tests/Generic/Stack/Stack.Generic.Tests.cs

@@ -11,7 +11,7 @@ namespace System.Collections.Tests
     /// <summary>
     /// Contains tests that ensure the correctness of the Stack class.
     /// </summary>
-    public abstract class Stack_Generic_Tests<T> : IGenericSharedAPI_Tests<T>
+    public abstract partial class Stack_Generic_Tests<T> : IGenericSharedAPI_Tests<T>
     {
         #region Stack<T> Helper Methods
 

src/System.Collections/tests/Generic/Stack/Stack.Generic.Tests.netcoreapp1.1.cs

@@ -0,0 +1,59 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using System.Linq;
+using Xunit;
+
+namespace System.Collections.Tests
+{
+    public abstract partial class Stack_Generic_Tests<T> : IGenericSharedAPI_Tests<T>
+    {       
+        [Theory]
+        [MemberData(nameof(ValidCollectionSizes))]
+        public void Stack_Generic_TryPop_AllElements(int count)
+        {
+            Stack<T> stack = GenericStackFactory(count);
+            List<T> elements = stack.ToList();
+            foreach (T element in elements)
+            {
+                T result;
+                Assert.True(stack.TryPop(out result));
+                Assert.Equal(element, result);
+            }
+        }
+
+        [Fact]
+        public void Stack_Generic_TryPop_EmptyStack_ReturnsFalse()
+        {
+            T result;
+            Assert.False(new Stack<T>().TryPop(out result));
+            Assert.Equal(default(T), result);
+        }
+
+        [Theory]
+        [MemberData(nameof(ValidCollectionSizes))]
+        public void Stack_Generic_TryPeek_AllElements(int count)
+        {
+            Stack<T> stack = GenericStackFactory(count);
+            List<T> elements = stack.ToList();
+            foreach (T element in elements)
+            {
+                T result;
+                Assert.True(stack.TryPeek(out result));
+                Assert.Equal(element, result);
+
+                stack.Pop();
+            }
+        }
+
+        [Fact]
+        public void Stack_Generic_TryPeek_EmptyStack_ReturnsFalse()
+        {
+            T result;
+            Assert.False(new Stack<T>().TryPeek(out result));
+            Assert.Equal(default(T), result);
+        }
+    }
+}

src/System.Collections/tests/System.Collections.Tests.builds

@@ -7,6 +7,10 @@
       <TargetGroup>netstandard1.7</TargetGroup>
       <TestTFMs>netcoreapp1.1</TestTFMs>
     </Project>
+    <Project Include="System.Collections.Tests.csproj">
+      <TargetGroup>netcoreapp1.1</TargetGroup>
+      <TestTFMs>netcoreapp1.1</TestTFMs>
+    </Project>
     <Project Include="System.Collections.Tests.csproj">
       <TestTFMs>netcore50;net46</TestTFMs>
       <OSGroup>Windows_NT</OSGroup>

src/System.Collections/tests/System.Collections.Tests.csproj

@@ -127,6 +127,7 @@
     <Compile Include="Generic\List\List.Generic.Tests.Sort.cs" />
     <Compile Include="Generic\Queue\Queue.Generic.cs" />
     <Compile Include="Generic\Queue\Queue.Generic.Tests.cs" />
+    <Compile Include="Generic\Queue\Queue.Generic.Tests.netcoreapp1.1.cs" Condition="'$(TargetGroup)'=='netcoreapp1.1'" />
     <Compile Include="Generic\Queue\Queue.Tests.cs" />
     <Compile Include="Generic\SortedDictionary\SortedDictionary.Generic.cs" />
     <Compile Include="Generic\SortedDictionary\SortedDictionary.Generic.Tests.cs" />
@@ -144,11 +145,12 @@
     <Compile Include="Generic\Stack\Stack.Tests.cs" />
     <Compile Include="Generic\Stack\Stack.Generic.cs" />
     <Compile Include="Generic\Stack\Stack.Generic.Tests.cs" />
+    <Compile Include="Generic\Stack\Stack.Generic.Tests.netcoreapp1.1.cs" Condition="'$(TargetGroup)'=='netcoreapp1.1'" />
     <Compile Include="$(CommonTestPath)\System\Diagnostics\DebuggerAttributes.cs">
       <Link>Common\System\Diagnostics\DebuggerAttributes.cs</Link>
     </Compile>
   </ItemGroup>
-  <ItemGroup Condition="'$(TargetGroup)'!='netstandard1.7'">
+  <ItemGroup Condition="'$(TargetGroup)'!='netstandard1.7' and '$(TargetGroup)'!='netcoreapp1.1'">
     <Compile Include="$(CommonPath)\System\SerializableAttribute.cs">
       <Link>Common\System\SerializableAttribute.cs</Link>
     </Compile>

src/System.Collections/tests/project.json

@@ -27,6 +27,11 @@
       "dependencies": {
         "System.Runtime.Serialization.Formatters": "4.3.0-beta-24522-03"
       }
+    },
+    "netcoreapp1.1": {
+      "dependencies": {
+        "System.Runtime.Serialization.Formatters": "4.3.0-beta-24522-03"
+      }
     }
   },
   "supports": {