1 files changed, 108 insertions, 0 deletions
diff --git a/src/ProtocolBuffers/Collections/Dictionaries.cs b/src/ProtocolBuffers/Collections/Dictionaries.cs
new file mode 100644
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+++ b/src/ProtocolBuffers/Collections/Dictionaries.cs
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+// 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;
+using System.Collections;
+using System.Collections.Generic;
+
+namespace Google.ProtocolBuffers.Collections {
+
+  /// <summary>
+  /// Non-generic class with generic methods which proxy to the non-generic methods
+  /// in the generic class.
+  /// </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 (!object.Equals(leftEntry.Value, rightValue)) {
+            return false;
+          }
+        } else {
+          IEnumerator leftEnumerator = leftEnumerable.GetEnumerator();
+          try {
+            foreach (object rightObject in rightEnumerable) {
+              if (!leftEnumerator.MoveNext()) {
+                return false;
+              }
+              if (!object.Equals(leftEnumerator.Current, rightObject)) {
+                return false;
+              }
+            }
+            if (leftEnumerator.MoveNext()) {
+              return false;
+            }
+          } finally {
+            if (leftEnumerator is IDisposable) {
+              ((IDisposable)leftEnumerator).Dispose();
+            }
+          }
+        }
+      }
+      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;
+    }
+  }
+}