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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;
}
}
}
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