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/*
* Copyright (c) 2008, Harald Kuhr
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * 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.
* * Neither the name "TwelveMonkeys" nor the
* names of its contributors may be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "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 COPYRIGHT OWNER OR
* CONTRIBUTORS 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.
*/
package com.twelvemonkeys.util;
/**
* DuplicateHandler
*
*
* @author Harald Kuhr
* @version $Id: //depot/branches/personal/haraldk/twelvemonkeys/release-2/twelvemonkeys-core/src/main/java/com/twelvemonkeys/util/DuplicateHandler.java#2 $
*/
public interface DuplicateHandler {
/**
* Resolves duplicates according to a certain strategy.
*
* @param pOld the old value
* @param pNew the new value
*
* @return the resolved value.
*
* @throws IllegalArgumentException is the arguments cannot be resolved for
* some reason.
*/
public T resolve(T pOld, T pNew);
/**
* Will use the first (old) value. Any new values will be discarded.
*
* @see CollectionUtil#invert(java.util.Map, java.util.Map, DuplicateHandler)
*/
public final static DuplicateHandler USE_FIRST_VALUE = new DuplicateHandler() {
/**
* Returns {@code pOld}.
*
* @param pOld the old value
* @param pNew the new value
*
* @return {@code pOld}
*/
public Object resolve(Object pOld, Object pNew) {
return pOld;
}
};
/**
* Will use the last (new) value. Any old values will be discarded
* (overwritten).
*
* @see CollectionUtil#invert(java.util.Map, java.util.Map, DuplicateHandler)
*/
public final static DuplicateHandler USE_LAST_VALUE = new DuplicateHandler() {
/**
* Returns {@code pNew}.
*
* @param pOld the old value
* @param pNew the new value
*
* @return {@code pNew}
*/
public Object resolve(Object pOld, Object pNew) {
return pNew;
}
};
/**
* Converts duplicats to an {@code Object} array.
*
* @see CollectionUtil#invert(java.util.Map, java.util.Map, DuplicateHandler)
*/
public final static DuplicateHandler DUPLICATES_AS_ARRAY = new DuplicateHandler() {
/**
* Returns an {@code Object} array, containing {@code pNew} as its
* last element.
*
* @param pOld the old value
* @param pNew the new value
*
* @return an {@code Object} array, containing {@code pNew} as its
* last element.
*/
public Object resolve(Object pOld, Object pNew) {
Object[] result;
if (pOld instanceof Object[]) {
Object[] old = ((Object[]) pOld);
result = new Object[old.length + 1];
System.arraycopy(old, 0, result, 0, old.length);
result[old.length] = pNew;
}
else {
result = new Object[] {pOld, pNew};
}
return result;
}
};
/**
* Converts duplicates to a comma-separated {@code String}.
* Note that all values should allready be {@code String}s if using this
* handler.
*
* @see CollectionUtil#invert(java.util.Map, java.util.Map, DuplicateHandler)
*/
public final static DuplicateHandler DUPLICATES_AS_CSV = new DuplicateHandler() {
/**
* Returns a comma-separated {@code String}, with the string
* representation of {@code pNew} as the last element.
*
* @param pOld the old value
* @param pNew the new value
*
* @return a comma-separated {@code String}, with the string
* representation of {@code pNew} as the last element.
*/
public String resolve(String pOld, String pNew) {
StringBuilder result = new StringBuilder(String.valueOf(pOld));
result.append(',');
result.append(pNew);
return result.toString();
}
};
}