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// **********************************************************************
//
// Copyright (c) 2003-2017 ZeroC, Inc. All rights reserved.
//
// This copy of Ice is licensed to you under the terms described in the
// ICE_LICENSE file included in this distribution.
//
// **********************************************************************
namespace Ice
{
public class CollectionComparer
{
//
// Try to compare two collections efficiently, by doing a reference
// and count comparison. If equality or inequality can be determined
// this way, 'result' contains the outcome of the comparison and the
// return value is true. Otherwise, if equality or inequality cannot
// be determined this way, 'result' and return value are both false.
//
private static bool cheapComparison(System.Collections.ICollection c1,
System.Collections.ICollection c2,
out bool result)
{
if(ReferenceEquals(c1, c2))
{
result = true;
return true; // Equal references means the collections are equal.
}
if(c1 == null || c2 == null)
{
result = false;
return true; // The references are not equal and one of them is null, so c1 and c2 are not equal.
}
if(c1.Count != c2.Count)
{
result = false;
return true; // Different number of elements, so c1 and c2 are not equal.
}
if(c1.Count == 0)
{
result = true;
return true; // Same number of elements, both zero, so c1 and c2 are equal.
}
result = false; // Couldn't get a result cheaply.
return false; // c1 and c2 may still be equal, but we have to compare elements to find out.
}
//
// Compare two dictionaries for value equality (as implemented by the Equals() method of its elements).
//
public static bool Equals(System.Collections.IDictionary d1, System.Collections.IDictionary d2)
{
try
{
bool result;
if(cheapComparison(d1, d2, out result))
{
return result;
}
System.Collections.ICollection keys1 = d1.Keys;
foreach(object k in keys1)
{
if(d2.Contains(k))
{
object v1 = d1[k];
object v2 = d2[k];
if(v1 == null)
{
if(v2 != null)
{
return false;
}
}
else
{
if(!v1.Equals(v2))
{
return false;
}
}
}
else
{
return false;
}
}
}
catch(System.Exception)
{
return false;
}
return true;
}
//
// Compare two collections for equality (as implemented by the Equals() method of its elements).
// Order is significant.
//
public static bool Equals(System.Collections.ICollection c1, System.Collections.ICollection c2)
{
try
{
bool result;
if(cheapComparison(c1, c2, out result))
{
return result;
}
System.Collections.IEnumerator e = c2.GetEnumerator();
foreach(object o in c1)
{
e.MoveNext();
if(!Equals(o, e.Current))
{
return false;
}
}
return true;
}
catch(System.Exception)
{
return false;
}
}
//
// Compare two collections for equality (as implemented by the Equals() method of its elements).
// Order is significant.
//
public static bool Equals(System.Collections.IEnumerable c1, System.Collections.IEnumerable c2)
{
try
{
if(ReferenceEquals(c1, c2))
{
return true; // Equal references means the collections are equal.
}
if(c1 == null || c2 == null)
{
return false; // The references are not equal and one of them is null, so c1 and c2 are not equal.
}
System.Collections.IEnumerator e1 = c1.GetEnumerator();
System.Collections.IEnumerator e2 = c2.GetEnumerator();
while(e1.MoveNext())
{
if(!e2.MoveNext())
{
return false; // c2 has fewer elements than c1.
}
if(e1.Current == null)
{
if(e2.Current != null)
{
return false;
}
}
else
{
if(!e1.Current.Equals(e2.Current))
{
return false;
}
}
}
if(e2.MoveNext())
{
return false; // c2 has more elements than c1.
}
return true;
}
catch(System.Exception)
{
return false;
}
}
}
}
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