Merge pull request #1491 from pdelvo/firstInLinePerf

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test/HelperTests/TokenHelperTests.cs

@@ -0,0 +1,44 @@
+// Copyright (c) Tunnel Vision Laboratories, LLC. All Rights Reserved.
+// Licensed under the Apache License, Version 2.0. See LICENSE in the project root for license information.
+
+namespace StyleCop.Analyzers.Test.HelperTests
+{
+    using System.Linq;
+    using Analyzers.Helpers;
+    using Microsoft.CodeAnalysis;
+    using Microsoft.CodeAnalysis.CSharp;
+    using Xunit;
+
+    public class TokenHelperTests
+    {
+        [Fact]
+        public void TestIsFirstInLineSpecialCase()
+        {
+            string testCode = @"class MyClass {
+} /// <summary>
+/// Text
+/// </summary>
+struct MyStruct { }";
+            var syntaxTree = CSharpSyntaxTree.ParseText(testCode);
+            var root = syntaxTree.GetRoot();
+
+            Assert.True(root.DescendantTokens().Single(i => i.IsKind(SyntaxKind.StructKeyword)).IsFirstInLine());
+        }
+
+        [Fact]
+        public void TestIsLastInLineSpecialCase()
+        {
+            string testCode = @"class MyClass {
+} /// <summary>
+/// Text
+/// </summary>
+struct /**
+Foo
+**/ MyStruct { }";
+            var syntaxTree = CSharpSyntaxTree.ParseText(testCode);
+            var root = syntaxTree.GetRoot();
+
+            Assert.True(root.DescendantTokens().Single(i => i.IsKind(SyntaxKind.StructKeyword)).IsLastInLine());
+        }
+    }
+}

StyleCop.Analyzers/StyleCop.Analyzers.Test/StyleCop.Analyzers.Test.csproj

@@ -169,6 +169,7 @@
     <Compile Include="Helpers\DiagnosticVerifier.Helper.cs" />
     <Compile Include="Helpers\ExclusionTestAnalyzer.cs" />
     <Compile Include="Helpers\TestDiagnosticProvider.cs" />
+    <Compile Include="HelperTests\TokenHelperTests.cs" />
     <Compile Include="HelperTests\TriviaHelperTests.cs" />
     <Compile Include="LayoutRules\SA1500\SA1500UnitTests.Blocks.cs" />
     <Compile Include="LayoutRules\SA1500\SA1500UnitTests.Classes.cs" />

StyleCop.Analyzers/StyleCop.Analyzers/Helpers/TokenHelpers.cs

@@ -18,8 +18,15 @@ internal static class TokenHelper
         /// <returns>true if token is first in line, otherwise false.</returns>
         internal static bool IsFirstInLine(this SyntaxToken token)
         {
-            SyntaxToken previousToken = token.GetPreviousToken();
-            return previousToken.IsKind(SyntaxKind.None) || previousToken.GetEndLine() < token.GetLine();
+            var fullLineSpan = token.SyntaxTree.GetLineSpan(token.FullSpan);
+
+            if (token.SyntaxTree == null || fullLineSpan.StartLinePosition.Character == 0)
+            {
+                return true;
+            }
+
+            var tokenLineSpan = token.SyntaxTree.GetLineSpan(token.Span);
+            return tokenLineSpan.StartLinePosition.Line != fullLineSpan.StartLinePosition.Line;
         }
 
         /// <summary>
@@ -29,7 +36,24 @@ internal static bool IsFirstInLine(this SyntaxToken token)
         /// <returns>true if token is last in line, otherwise false.</returns>
         internal static bool IsLastInLine(this SyntaxToken token)
         {
-            SyntaxToken nextToken = token.GetNextToken();
+            var fullLineSpan = token.SyntaxTree.GetLineSpan(token.FullSpan);
+
+            if (token.SyntaxTree == null || fullLineSpan.EndLinePosition.Character == 0)
+            {
+                return true;
+            }
+
+            var tokenLineSpan = token.SyntaxTree.GetLineSpan(token.Span);
+
+            if (tokenLineSpan.EndLinePosition.Line != fullLineSpan.EndLinePosition.Line
+                || token.SyntaxTree.Length == token.FullSpan.End)
+            {
+                return true;
+            }
+
+            // Use the slow path because we cant be sure if a multi line trivia is following this
+            // token.
+            var nextToken = token.GetNextToken();
             return nextToken.IsKind(SyntaxKind.None) || token.GetEndLine() < nextToken.GetLine();
         }