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/*
* Copyright (c) 2000, 2021, Oracle and/or its affiliates.
*
* Licensed under the Universal Permissive License v 1.0 as shown at
* http://oss.oracle.com/licenses/upl.
*/
package com.tangosol.util.comparator;
import com.tangosol.io.ExternalizableLite;
import com.tangosol.io.pof.PofReader;
import com.tangosol.io.pof.PofWriter;
import com.tangosol.io.pof.PortableObject;
import com.tangosol.util.Base;
import com.tangosol.util.ExternalizableHelper;
import com.tangosol.util.QueryMap;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import java.io.Serializable;
import java.util.Comparator;
import javax.json.bind.annotation.JsonbProperty;
/**
* Composite comparator implementation based on a collection of comparators.
* The comparators in the array assumed to be sorted according to their
* priorities; only in a case when the n-th comparator cannot determine the
* order of the passed objects:
*
* aComparator[n].compare(o1, o2) == 0
*
* the (n+1)-th comparator will be applied to calculate the value.
*
* @author gg 2002.11.14
*/
public class ChainedComparator
extends Base
implements Comparator, QueryMapComparator, EntryAwareComparator,
Serializable, ExternalizableLite, PortableObject
{
// ----- constructors ---------------------------------------------------
/**
* Default constructor (for ExternalizableLite and PortableObject).
*/
public ChainedComparator()
{
}
/**
* Construct a ChainedComparator.
*
* @param aComparator the comparator array
*/
@SafeVarargs
public ChainedComparator(Comparator... aComparator)
{
azzert(aComparator != null);
m_aComparator = aComparator;
}
// ----- Comparator interface -------------------------------------------
/**
* Compares its two arguments for order. Returns a negative integer,
* zero, or a positive integer as the first argument is less than, equal
* to, or greater than the second.
*
* @param o1 the first object to be compared
* @param o2 the second object to be compared
*
* @return a negative integer, zero, or a positive integer as the first
* argument is less than, equal to, or greater than the second
*
* @throws ClassCastException if the arguments' types prevent them from
* being compared by this Comparator.
*/
public int compare(T o1, T o2)
{
Comparator[] aComparator = getComparators();
for (int i = 0, c = aComparator.length; i < c; i++)
{
int nResult = aComparator[i].compare(o1, o2);
if (nResult != 0)
{
return nResult;
}
}
return 0;
}
// ----- QueryMapComparator interface -----------------------------------
/**
* Compare two entries based on the rules specified by {@link Comparator}.
*
* This implementation simply passes on this invocation to the wrapped
* Comparator objects if they too implement this interface, or invokes
* their default compare method passing the values extracted from the
* passed entries.
*/
public int compareEntries(QueryMap.Entry entry1, QueryMap.Entry entry2)
{
Comparator[] aComparator = getComparators();
for (int i = 0, c = aComparator.length; i < c; i++)
{
Comparator comparator = aComparator[i];
int nResult = comparator instanceof QueryMapComparator
? ((QueryMapComparator) comparator).compareEntries(entry1, entry2)
: compare(entry1.getValue(), entry2.getValue());
if (nResult != 0)
{
return nResult;
}
}
return 0;
}
// ----- EntryAwareComparator interface ---------------------------------
/**
* {@inheritDoc}
*
* @return true iff all the underlying comparators implement the
* EntryAwareComparator interface and all isKeyComparator()
* calls return true
*/
public boolean isKeyComparator()
{
Comparator[] aComparator = getComparators();
for (int i = 0, c = aComparator.length; i < c; i++)
{
if (!(SafeComparator.isKeyComparator(aComparator[i])))
{
return false;
}
}
return true;
}
// ----- Object methods -------------------------------------------------
/**
* Return a human-readable description for this ChainedComparator.
*
* @return a String description of the ChainedComparator
*/
public String toString()
{
StringBuilder sb = new StringBuilder("ChainedComparator(");
Comparator[] aComparator = m_aComparator;
for (int i = 0, c = aComparator.length; i < c; i++)
{
if (i > 0)
{
sb.append(", ");
}
sb.append(aComparator[i]);
}
sb.append(')');
return sb.toString();
}
/**
* Determine if two ChainedComparator objects are equal.
*
* @param o the other comparator
*
* @return true if the passed object is equal to this ChainedComparator
*/
public boolean equals(Object o)
{
return o instanceof ChainedComparator &&
equalsDeep(m_aComparator, ((ChainedComparator) o).m_aComparator);
}
/**
* Return the hash code for this comparator.
*
* @return the hash code value for this comparator
*/
public int hashCode()
{
Comparator[] aComparator = m_aComparator;
int nHash = 0;
for (int i = 0, c = aComparator.length; i < c; i++)
{
nHash += aComparator[i].hashCode();
}
return nHash;
}
// ----- accessors ------------------------------------------------------
/**
* Obtain the underlying Comparator array.
*
* @return the Comparator array
*/
public Comparator[] getComparators()
{
return m_aComparator;
}
// ----- ExternalizableLite interface -----------------------------------
/**
* {@inheritDoc}
*/
public void readExternal(DataInput in)
throws IOException
{
int cComparators = ExternalizableHelper.readInt(in);
azzert(cComparators < 16384, "Unexpected number of chained comparators");
Comparator[] aComparator = new Comparator[cComparators];
for (int i = 0; i < cComparators; i++)
{
aComparator[i] = (Comparator) ExternalizableHelper.readObject(in);
}
m_aComparator = aComparator;
}
/**
* {@inheritDoc}
*/
public void writeExternal(DataOutput out)
throws IOException
{
Comparator[] aComparator = m_aComparator;
int cComparators = aComparator.length;
ExternalizableHelper.writeInt(out, cComparators);
for (int i = 0; i < cComparators; i++)
{
ExternalizableHelper.writeObject(out, aComparator[i]);
}
}
// ----- PortableObject interface ---------------------------------------
/**
* {@inheritDoc}
*/
public void readExternal(PofReader in)
throws IOException
{
m_aComparator = in.readArray(0, Comparator[]::new);
}
/**
* {@inheritDoc}
*/
public void writeExternal(PofWriter out)
throws IOException
{
out.writeObjectArray(0, m_aComparator);
}
// ----- constants ------------------------------------------------------
/**
* Empty array of Comparators.
*/
private static final Comparator[] EMPTY_COMPARATOR_ARRAY = new Comparator[0];
// ----- data members ---------------------------------------------------
/**
* The Comparator array.
*/
@JsonbProperty("comparators")
protected Comparator[] m_aComparator;
}