Rationalize ByteSequenceComparer.

ByteSequenceComparer has been updated as follows:
- The implementation of IEqualityComparer<IEnumerable<byte>> has been removed
- The implementations of IEqualityComparer<{byte[], ImmutableArray<byte>}> are now explicit
- The various overloads of EqualsValue and GetHashCodeValue have been renamed to Equals and GetHasCode, respectively.
***NO_CI***
 (changeset 1395450)

Src/Compilers/CSharp/Portable/Symbols/AssemblySymbol.cs

@@ -966,7 +966,7 @@ protected IVTConclusion PerformIVTCheck(ImmutableArray<byte> key, AssemblyIdenti
             bool q1 = otherIdentity.IsStrongName;
             bool q2 = !key.IsDefaultOrEmpty;
             bool q3 = !this.PublicKey.IsDefaultOrEmpty;
-            bool q4 = (q2 & q3) && ByteSequenceComparer.Instance.Equals(key, this.PublicKey);
+            bool q4 = (q2 & q3) && ByteSequenceComparer.Equals(key, this.PublicKey);
 
             // Cases 2, 3, 7 and 8:
             if (q2 && !q4)

Src/Compilers/CSharp/Test/Emit/Attributes/InternalsVisibleToAndStrongNameTests.cs

@@ -77,7 +77,7 @@ public void PubKeyFromKeyFileAttribute()
 
         var other = CreateCompilationWithMscorlib(s, options: TestOptions.ReleaseDll.WithStrongNameProvider(DefaultProvider));
         other.VerifyDiagnostics();
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey));
 
         CompileAndVerify(other, symbolValidator: (ModuleSymbol m) =>
             {
@@ -121,7 +121,7 @@ public void PubKeyFromKeyFileAttribute_AssemblyKeyFileResolver()
 
         comp.VerifyDiagnostics();
 
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
     }
 
     [Fact]
@@ -149,7 +149,7 @@ public void PubKeyFromKeyFileAttribute_AssemblyKeyFileResolver_RelativeToCurrent
             TestOptions.ReleaseDll.WithStrongNameProvider(GetProviderWithPath(PathUtilities.CombineAbsoluteAndRelativePaths(keyFileDir, @"TempSubDir\"))));
 
         Assert.Empty(comp.GetDiagnostics());
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
     }
     
     [Fact]
@@ -160,7 +160,7 @@ public void PubKeyFromKeyContainerAttribute()
 
         var other = CreateCompilationWithMscorlib(s, options: TestOptions.ReleaseDll.WithStrongNameProvider(DefaultProvider));
         other.VerifyDiagnostics();
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey));
 
         CompileAndVerify(other, symbolValidator: (ModuleSymbol m) =>
         {
@@ -186,7 +186,7 @@ public void PubKeyFromKeyFileOptions()
         var other = CreateCompilationWithMscorlib(s, options: TestOptions.ReleaseDll.WithCryptoKeyFile(KeyPairFile).WithStrongNameProvider(DefaultProvider));
 
         other.VerifyDiagnostics();
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey));
     }
 
     [Fact]
@@ -215,7 +215,7 @@ public void PubKeyFromKeyFileOptions_ReferenceResolver()
             TestOptions.ReleaseDll.WithCryptoKeyFile(keyFileName).WithStrongNameProvider(GetProviderWithPath(keyFileDir)));
 
         Assert.Empty(comp.GetDiagnostics());
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
     }
 
     [Fact]
@@ -225,7 +225,7 @@ public void PubKeyFromKeyFileOptionsJustPublicKey()
         var other = CreateCompilationWithMscorlib(s, 
             options: TestOptions.ReleaseDll.WithCryptoKeyFile(PublicKeyFile).WithDelaySign(true).WithStrongNameProvider(DefaultProvider));
         other.VerifyDiagnostics();
-        Assert.True(ByteSequenceComparer.Instance.Equals(TestResources.SymbolsTests.General.snPublicKey.AsImmutableOrNull(), other.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(TestResources.SymbolsTests.General.snPublicKey.AsImmutableOrNull(), other.Assembly.Identity.PublicKey));
     }
 
     [Fact]
@@ -257,7 +257,7 @@ public void PubKeyFromKeyFileOptionsJustPublicKey_ReferenceResolver()
             new[] { MscorlibRef },
             TestOptions.ReleaseDll.WithCryptoKeyFile(publicKeyFileName).WithDelaySign(true).WithStrongNameProvider(GetProviderWithPath(publicKeyFileDir)));
         Assert.Empty(comp.GetDiagnostics());
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey));
     }
 
     [Fact]
@@ -313,7 +313,7 @@ public void KeyFileAttributeOptionConflict()
             options: TestOptions.ReleaseDll.WithCryptoKeyFile(KeyPairFile).WithStrongNameProvider(DefaultProvider));
 
         other.VerifyDiagnostics(Diagnostic(ErrorCode.WRN_CmdOptionConflictsSource).WithArguments("CryptoKeyFile", "System.Reflection.AssemblyKeyFileAttribute"));
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey));
     }
 
     [Fact]
@@ -325,7 +325,7 @@ public void KeyContainerAttributeOptionConflict()
             options: TestOptions.ReleaseDll.WithCryptoKeyContainer("RoslynTestContainer").WithStrongNameProvider(DefaultProvider));
 
         other.VerifyDiagnostics(Diagnostic(ErrorCode.WRN_CmdOptionConflictsSource).WithArguments("CryptoKeyContainer", "System.Reflection.AssemblyKeyNameAttribute"));
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey));
     }
 
     [Fact]
@@ -527,7 +527,7 @@ public class A
             assemblyName: "John",
             options: TestOptions.ReleaseDll.WithStrongNameProvider(DefaultProvider));
 
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, requestor.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, requestor.Assembly.Identity.PublicKey));
         Assert.Empty(requestor.GetDiagnostics());
     }
 
@@ -554,7 +554,7 @@ public class A
             assemblyName: "John",
             options: TestOptions.ReleaseDll.WithStrongNameProvider(DefaultProvider));
 
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, requestor.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, requestor.Assembly.Identity.PublicKey));
         requestor.VerifyDiagnostics(Diagnostic(ErrorCode.ERR_FriendRefSigningMismatch, null, new object[] { "Paul, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null" }));
     }
 
@@ -582,7 +582,7 @@ public class A
           assemblyName: "John",
           options: TestOptions.ReleaseDll.WithStrongNameProvider(DefaultProvider));
 
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, requestor.Assembly.Identity.PublicKey));
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, requestor.Assembly.Identity.PublicKey));
         requestor.VerifyDiagnostics(Diagnostic(ErrorCode.ERR_FriendRefNotEqualToThis, null, new object[] { "Paul, Version=0.0.0.0, Culture=neutral, PublicKeyToken=ce65828c82a341f2" }));
     }
 

Src/Compilers/Core/Desktop/DesktopStrongNameProvider.cs

@@ -295,7 +295,7 @@ internal static ImmutableArray<byte> GetPublicKey(byte[] keyFileContents)
             try
             {
                 var lastSeen = lastSeenKeyPair;
-                if (lastSeen != null && ByteSequenceComparer.ValueEquals(lastSeen.Item1, keyFileContents))
+                if (lastSeen != null && ByteSequenceComparer.Equals(lastSeen.Item1, keyFileContents))
                 {
                     return lastSeen.Item2;
                 }

Src/Compilers/Core/Portable/Collections/ByteSequenceComparer.cs

@@ -2,13 +2,14 @@
 
 using System.Collections.Generic;
 using System.Collections.Immutable;
+using System.Diagnostics;
 using System.Linq;
 using Microsoft.CodeAnalysis.Text;
 using Roslyn.Utilities;
 
 namespace Microsoft.CodeAnalysis.Collections
 {
-    internal sealed class ByteSequenceComparer : IEqualityComparer<byte[]>, IEqualityComparer<IEnumerable<byte>>, IEqualityComparer<ImmutableArray<byte>>
+    internal sealed class ByteSequenceComparer : IEqualityComparer<byte[]>, IEqualityComparer<ImmutableArray<byte>>
     {
         internal static readonly ByteSequenceComparer Instance = new ByteSequenceComparer();
 
@@ -16,41 +17,30 @@ private ByteSequenceComparer()
         {
         }
 
-        public bool Equals(IEnumerable<byte> x, IEnumerable<byte> y)
+        internal static bool Equals(ImmutableArray<byte> x, ImmutableArray<byte> y)
         {
-            if (ReferenceEquals(x, y))
+            if (x == y)
             {
                 return true;
             }
 
-            if (x == null || y == null)
+            if (x.IsDefault || y.IsDefault || x.Length != y.Length)
             {
                 return false;
             }
 
-            var ax = x as byte[];
-            var ay = y as byte[];
-            return (ax != null && ay != null)
-                ? Equals(ax, ay)
-                : x.SequenceEqual(y);
-        }
-
-        public bool Equals(ImmutableArray<byte> x, ImmutableArray<byte> y)
-        {
-            return ValueEquals(x, y);
-        }
-
-        internal static bool ValueEquals(ImmutableArray<byte> x, ImmutableArray<byte> y)
-        {
-            return x.SequenceEqual(y);
-        }
+            for (var i = 0; i < x.Length; i++)
+            {
+                if (x[i] != y[i])
+                {   
+                    return false;
+                }
+            }
 
-        public bool Equals(byte[] x, byte[] y)
-        {
-            return ValueEquals(x, y);
+            return true;
         }
 
-        internal static bool ValueEquals(byte[] x, byte[] y)
+        internal static bool Equals(byte[] x, byte[] y)
         {
             if (ReferenceEquals(x, y))
             {
@@ -73,54 +63,38 @@ internal static bool ValueEquals(byte[] x, byte[] y)
             return true;
         }
 
-        public int GetHashCode(IEnumerable<byte> x)
-        {
-            if (x == null)
-            {
-                return 0;
-            }
+        // Both hash computations below use the FNV-1a algorithm (http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function).
 
-            var ax = x as byte[];
-            if (ax != null)
-            {
-                return GetHashCode(ax);
-            }
-
-            var result = 7;
-            foreach (var b in x)
-            {
-                result = (result << 5) ^ b;
-            }
+        internal static int GetHashCode(byte[] x)
+        {
+            Debug.Assert(x != null);
+            return Hash.GetFNVHashCode(x);
+        }
 
-            return result;
+        internal static int GetHashCode(ImmutableArray<byte> x)
+        {
+            Debug.Assert(!x.IsDefault);
+            return Hash.GetFNVHashCode(x);
         }
 
-        public int GetHashCode(byte[] x)
+        bool IEqualityComparer<byte[]>.Equals(byte[] x, byte[] y)
         {
-            return GetValueHashCode(x);
+            return Equals(x, y);
         }
 
-        /// <summary>
-        /// Compute the FNV-1a hash code for a sequence of bytes.
-        /// See http://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function
-        /// </summary>
-        /// <param name="x">The sequence of bytes</param>
-        /// <returns>The FNV-1a hash code for the input sequence</returns>
-        /// <exception cref="System.NullReferenceException">The input sequence was null (IsDefault)</exception>
-        public int GetHashCode(ImmutableArray<byte> x)
+        int IEqualityComparer<byte[]>.GetHashCode(byte[] x)
         {
-            return Hash.GetFNVHashCode(x);
+            return GetHashCode(x);
         }
 
-        // This uses FNV1a as a string hash
-        internal static int GetValueHashCode(byte[] x)
+        bool IEqualityComparer<ImmutableArray<byte>>.Equals(ImmutableArray<byte> x, ImmutableArray<byte> y)
         {
-            if (x == null)
-            {
-                return 0;
-            }
+            return Equals(x, y);
+        }
 
-            return Hash.GetFNVHashCode(x);
+        int IEqualityComparer<ImmutableArray<byte>>.GetHashCode(ImmutableArray<byte> x)
+        {
+            return GetHashCode(x);
         }
     }
-}
\ No newline at end of file
+}

Src/Compilers/Core/Portable/PEWriter/MetadataWriter.cs

@@ -2492,7 +2492,7 @@ public bool Equals(IAssemblyReference x, IAssemblyReference y)
 
                 return
                     x.Version.Equals(y.Version) &&
-                    ByteSequenceComparer.Instance.Equals(x.PublicKeyToken, y.PublicKeyToken) &&
+                    ByteSequenceComparer.Equals(x.PublicKeyToken, y.PublicKeyToken) &&
                     x.Name == y.Name &&
                     x.Culture == y.Culture;
             }
@@ -2500,7 +2500,7 @@ public bool Equals(IAssemblyReference x, IAssemblyReference y)
             public int GetHashCode(IAssemblyReference reference)
             {
                 return Hash.Combine(reference.Version,
-                       Hash.Combine(ByteSequenceComparer.Instance.GetHashCode(reference.PublicKeyToken),
+                       Hash.Combine(ByteSequenceComparer.GetHashCode(reference.PublicKeyToken),
                        Hash.Combine(reference.Name.GetHashCode(),
                        Hash.Combine(reference.Culture, 0))));
             }

Src/Compilers/VisualBasic/Portable/Symbols/AssemblySymbol.vb

@@ -565,7 +565,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
                     ' key is NullOrEmpty, Me.PublicKey is not.
                     result = IVTConclusion.NoRelationshipClaimed
                 End If
-            ElseIf ByteSequenceComparer.Instance.Equals(key, Me.PublicKey) Then
+            ElseIf ByteSequenceComparer.Equals(key, Me.PublicKey) Then
                 result = If(otherIdentity.IsStrongName, IVTConclusion.Match, IVTConclusion.OneSignedOneNot)
             Else
                 result = IVTConclusion.PublicKeyDoesntMatch
@@ -646,4 +646,4 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
 #End Region
 
     End Class
-End Namespace
\ No newline at end of file
+End Namespace

Src/Compilers/VisualBasic/Test/Emit/Attributes/InternalsVisibleToAndStrongNameTests.vb

@@ -50,7 +50,7 @@ Public Class InternalsVisibleToAndStrongNameTests
             TestOptions.ReleaseDll.WithStrongNameProvider(DefaultProvider))
 
         other.VerifyDiagnostics()
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>
@@ -79,7 +79,7 @@ Public Class InternalsVisibleToAndStrongNameTests
             TestOptions.ReleaseDll.WithStrongNameProvider(GetProviderWithPath(keyFileDir)))
 
         comp.VerifyDiagnostics()
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>
@@ -108,7 +108,7 @@ Public Class InternalsVisibleToAndStrongNameTests
             options:=TestOptions.ReleaseDll.WithStrongNameProvider(GetProviderWithPath(PathUtilities.CombineAbsoluteAndRelativePaths(keyFileDir, "TempSubDir\"))))
 
         comp.VerifyDiagnostics()
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>
@@ -126,7 +126,7 @@ End Class
 </compilation>, TestOptions.ReleaseDll.WithStrongNameProvider(DefaultProvider))
 
         other.VerifyDiagnostics()
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>
@@ -144,7 +144,7 @@ End Class
         options:=TestOptions.ReleaseDll.WithCryptoKeyFile(KeyPairFile).WithStrongNameProvider(DefaultProvider))
 
         other.VerifyDiagnostics()
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, other.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, other.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>
@@ -181,7 +181,7 @@ End Class
             options:=TestOptions.ReleaseDll.WithCryptoKeyFile(keyFileName).WithStrongNameProvider(GetProviderWithPath(keyFileDir)))
 
         comp.VerifyDiagnostics()
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>
@@ -199,7 +199,7 @@ End Class
         Dim other = CreateCompilationWithMscorlib(s, options:=TestOptions.ReleaseDll.WithCryptoKeyFile(PublicKeyFile).WithDelaySign(True).WithStrongNameProvider(DefaultProvider))
 
         Assert.Empty(other.GetDiagnostics())
-        Assert.True(ByteSequenceComparer.Instance.Equals(TestResources.SymbolsTests.General.snPublicKey.AsImmutableOrNull(), other.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(TestResources.SymbolsTests.General.snPublicKey.AsImmutableOrNull(), other.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>
@@ -239,7 +239,7 @@ End Class
             options:=TestOptions.ReleaseDll.WithCryptoKeyFile(publicKeyFileName).WithDelaySign(True).WithStrongNameProvider(GetProviderWithPath(publicKeyFileDir)))
 
         comp.VerifyDiagnostics()
-        Assert.True(ByteSequenceComparer.Instance.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
+        Assert.True(ByteSequenceComparer.Equals(PublicKey, comp.Assembly.Identity.PublicKey))
     End Sub
 
     <Fact>