1 files changed, 122 insertions, 0 deletions
diff --git a/csharp/src/ProtocolBuffers/Collections/Dictionaries.cs b/csharp/src/ProtocolBuffers/Collections/Dictionaries.cs
new file mode 100644
index 00000000..1f3791b1
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+++ b/csharp/src/ProtocolBuffers/Collections/Dictionaries.cs
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+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://github.com/jskeet/dotnet-protobufs/
+// Original C++/Java/Python code:
+// http://code.google.com/p/protobuf/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+using System;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Google.ProtocolBuffers.Collections
+{
+    /// <summary>
+    /// Utility class for dictionaries.
+    /// </summary>
+    public static class Dictionaries
+    {
+        /// <summary>
+        /// Compares two dictionaries for equality. Each value is compared with equality using Equals
+        /// for non-IEnumerable implementations, and using EnumerableEquals otherwise.
+        /// TODO(jonskeet): This is clearly pretty slow, and involves lots of boxing/unboxing...
+        /// </summary>
+        public static bool Equals<TKey, TValue>(IDictionary<TKey, TValue> left, IDictionary<TKey, TValue> right)
+        {
+            if (left.Count != right.Count)
+            {
+                return false;
+            }
+            foreach (KeyValuePair<TKey, TValue> leftEntry in left)
+            {
+                TValue rightValue;
+                if (!right.TryGetValue(leftEntry.Key, out rightValue))
+                {
+                    return false;
+                }
+
+                IEnumerable leftEnumerable = leftEntry.Value as IEnumerable;
+                IEnumerable rightEnumerable = rightValue as IEnumerable;
+                if (leftEnumerable == null || rightEnumerable == null)
+                {
+                    if (!Equals(leftEntry.Value, rightValue))
+                    {
+                        return false;
+                    }
+                }
+                else
+                {
+                    if (!Enumerables.Equals(leftEnumerable, rightEnumerable))
+                    {
+                        return false;
+                    }
+                }
+            }
+            return true;
+        }
+
+        public static IDictionary<TKey, TValue> AsReadOnly<TKey, TValue>(IDictionary<TKey, TValue> dictionary)
+        {
+            return dictionary.IsReadOnly ? dictionary : new ReadOnlyDictionary<TKey, TValue>(dictionary);
+        }
+
+        /// <summary>
+        /// Creates a hashcode for a dictionary by XORing the hashcodes of all the fields
+        /// and values. (By XORing, we avoid ordering issues.)
+        /// TODO(jonskeet): Currently XORs other stuff too, and assumes non-null values.
+        /// </summary>
+        public static int GetHashCode<TKey, TValue>(IDictionary<TKey, TValue> dictionary)
+        {
+            int ret = 31;
+            foreach (KeyValuePair<TKey, TValue> entry in dictionary)
+            {
+                int hash = entry.Key.GetHashCode() ^ GetDeepHashCode(entry.Value);
+                ret ^= hash;
+            }
+            return ret;
+        }
+
+        /// <summary>
+        /// Determines the hash of a value by either taking it directly or hashing all the elements
+        /// for IEnumerable implementations.
+        /// </summary>
+        private static int GetDeepHashCode(object value)
+        {
+            IEnumerable iterable = value as IEnumerable;
+            if (iterable == null)
+            {
+                return value.GetHashCode();
+            }
+            int hash = 29;
+            foreach (object element in iterable)
+            {
+                hash = hash*37 + element.GetHashCode();
+            }
+            return hash;
+        }
+    }
+}
+\ No newline at end of file