antlr/runtime/CSharp/Antlr4.Runtime/Sharpen/DictionaryExtensions.cs

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2013-02-20 23:30:04 +08:00
/*
* [The "BSD license"]
* Copyright (c) 2013 Terence Parr
* Copyright (c) 2013 Sam Harwell
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
*/
namespace Sharpen
{
using System.Collections.Generic;
public static class DictionaryExtensions
{
public static TValue Get<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key)
where TValue : class
{
TValue value;
if (!dictionary.TryGetValue(key, out value))
return null;
return value;
}
public static TValue Put<TKey, TValue>(this IDictionary<TKey, TValue> dictionary, TKey key, TValue value)
where TValue : class
{
TValue previous;
if (!dictionary.TryGetValue(key, out previous))
previous = null;
dictionary[key] = value;
return previous;
}
}
}