/* | |
* Licensed to the Apache Software Foundation (ASF) under one | |
* or more contributor license agreements. See the NOTICE file | |
* distributed with this work for additional information | |
* regarding copyright ownership. The ASF licenses this file | |
* to you 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. | |
*/ | |
package org.codehaus.groovy.runtime; | |
import groovy.lang.GroovyRuntimeException; | |
import org.codehaus.groovy.runtime.typehandling.DefaultTypeTransformation; | |
import java.util.Comparator; | |
/** | |
* Compares two objects using Groovy's friendly comparison algorithm, i.e. | |
* handles nulls gracefully (nul being less than everything else) and | |
* performs numeric type coercion if required. | |
*/ | |
public class NumberAwareComparator<T> implements Comparator<T> { | |
public int compare(T o1, T o2) { | |
try { | |
return DefaultTypeTransformation.compareTo(o1, o2); | |
} catch (ClassCastException cce) { | |
/* ignore */ | |
} catch (GroovyRuntimeException gre) { | |
/* ignore */ | |
} catch (IllegalArgumentException iae) { | |
/* ignore */ | |
} | |
// since the object does not have a valid compareTo method | |
// we compare using the hashcodes. null cases are handled by | |
// DefaultTypeTransformation.compareTo | |
// This is not exactly a mathematical valid approach, since we compare object | |
// that cannot be compared. To avoid strange side effects we do a pseudo order | |
// using hashcodes, but without equality. Since then an x and y with the same | |
// hashcodes will behave different depending on if we compare x with y or | |
// x with y, the result might be unstable as well. Setting x and y to equal | |
// may mean the removal of x or y in a sorting operation, which we don't want. | |
int x1 = o1.hashCode(); | |
int x2 = o2.hashCode(); | |
if (x1 == x2 && o1.equals(o2)) return 0; | |
if (x1 > x2) return 1; | |
return -1; | |
} | |
} |