1 files changed, 187 insertions, 0 deletions
diff --git a/src/ProtocolBuffers/ByteString.cs b/src/ProtocolBuffers/ByteString.cs
new file mode 100644
index 00000000..26816d9c
--- /dev/null
+++ b/src/ProtocolBuffers/ByteString.cs
@@ -0,0 +1,187 @@
+using System;
+using System.Collections;
+using System.Collections.Generic;
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.
+// http://code.google.com/p/protobuf/
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+using System.Text;
+
+namespace Google.ProtocolBuffers {
+  /// <summary>
+  /// Immutable array of bytes.
+  /// TODO(jonskeet): Implement the common collection interfaces?
+  /// </summary>
+  public sealed class ByteString : IEnumerable<byte>, IEquatable<ByteString> {
+
+    private static readonly ByteString empty = new ByteString(new byte[0]);
+
+    private readonly byte[] bytes;
+
+    /// <summary>
+    /// Constructs a new ByteString from the given byte array. The array is
+    /// *not* copied, and must not be modified after this constructor is called.
+    /// </summary>
+    private ByteString(byte[] bytes) {
+      this.bytes = bytes;
+    }
+
+    /// <summary>
+    /// Returns an empty ByteString.
+    /// </summary>
+    public static ByteString Empty {
+      get { return empty; }
+    }
+
+    /// <summary>
+    /// Returns the length of this ByteString in bytes.
+    /// </summary>
+    public int Length {
+      get { return bytes.Length; }
+    }
+
+    public bool IsEmpty {
+      get { return Length == 0; }
+    }
+
+    public byte[] ToByteArray() {
+      return (byte[])bytes.Clone();
+    }
+
+    /// <summary>
+    /// Constructs a ByteString from the given array. The contents
+    /// are copied, so further modifications to the array will not
+    /// be reflected in the returned ByteString.
+    /// </summary>
+    public static ByteString CopyFrom(byte[] bytes) {
+      return new ByteString((byte[]) bytes.Clone());
+    }
+
+    /// <summary>
+    /// Constructs a ByteString from a portion of a byte array.
+    /// </summary>
+    public static ByteString CopyFrom(byte[] bytes, int offset, int count) {
+      byte[] portion = new byte[count];
+      Array.Copy(bytes, offset, portion, 0, count);
+      return new ByteString(portion);
+    }
+
+    /// <summary>
+    /// Creates a new ByteString by encoding the specified text with
+    /// the given encoding.
+    /// </summary>
+    public static ByteString CopyFrom(string text, Encoding encoding) {
+      return new ByteString(encoding.GetBytes(text));
+    }
+
+    /// <summary>
+    /// Creates a new ByteString by encoding the specified text in UTF-8.
+    /// </summary>
+    public static ByteString CopyFromUtf8(string text) {
+      return CopyFrom(text, Encoding.UTF8);
+    }
+    
+    /// <summary>
+    /// Retuns the byte at the given index.
+    /// </summary>
+    public byte this[int index] {
+      get { return bytes[index]; }
+    }
+
+    public string ToString(Encoding encoding) {
+      return encoding.GetString(bytes);
+    }
+
+    public string ToStringUtf8() {
+      return ToString(Encoding.UTF8);
+    }
+
+    public IEnumerator<byte> GetEnumerator() {
+      return ((IEnumerable<byte>) bytes).GetEnumerator();
+    }
+
+    IEnumerator IEnumerable.GetEnumerator() {
+      return GetEnumerator();
+    }
+
+    /// <summary>
+    /// Creates a CodedInputStream from this ByteString's data.
+    /// </summary>
+    public CodedInputStream CreateCodedInput() {
+      
+      // We trust CodedInputStream not to reveal the provided byte array or modify it
+      return CodedInputStream.CreateInstance(bytes);
+    }
+
+    // TODO(jonskeet): CopyTo if it turns out to be required
+
+    public override bool Equals(object obj) {
+      ByteString other = obj as ByteString;
+      if (obj == null) {
+        return false;
+      }
+      return Equals(other);
+    }
+
+    public override int GetHashCode() {
+      int ret = 23;
+      foreach (byte b in bytes) {
+        ret = (ret << 8) | b;
+      }
+      return ret;
+    }
+
+    public bool Equals(ByteString other) {
+      if (other.bytes.Length != bytes.Length) {
+        return false;
+      }
+      for (int i = 0; i < bytes.Length; i++) {
+        if (other.bytes[i] != bytes[i]) {
+          return false;
+        }
+      }
+      return true;
+    }
+
+    /// <summary>
+    /// Builder for ByteStrings which allows them to be created without extra
+    /// copying being involved. This has to be a nested type in order to have access
+    /// to the private ByteString constructor.
+    /// </summary>
+    internal sealed class CodedBuilder {
+      private readonly CodedOutputStream output;
+      private readonly byte[] buffer;
+
+      internal CodedBuilder(int size) {
+        buffer = new byte[size];
+        output = CodedOutputStream.CreateInstance(buffer);
+      }
+
+      public ByteString Build() {
+        output.CheckNoSpaceLeft();
+
+        // We can be confident that the CodedOutputStream will not modify the
+        // underlying bytes anymore because it already wrote all of them.  So,
+        // no need to make a copy.
+        return new ByteString(buffer);
+      }
+
+      public CodedOutputStream CodedOutput {
+        get {
+          return output;
+        }
+      }
+    }
+  }
+}