org.eclipse.jgit.diff.HashedSequencePair Maven / Gradle / Ivy
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package org.eclipse.jgit.diff;
/**
* Wraps two {@link Sequence} instances to cache their element hash codes.
*
* This pair wraps two sequences that contain cached hash codes for the input
* sequences.
*
* @param
* the base sequence type.
*/
public class HashedSequencePair {
private final SequenceComparator cmp;
private final S baseA;
private final S baseB;
private HashedSequence cachedA;
private HashedSequence cachedB;
/**
* Construct a pair to provide fast hash codes.
*
* @param cmp
* the base comparator for the sequence elements.
* @param a
* the A sequence.
* @param b
* the B sequence.
*/
public HashedSequencePair(SequenceComparator cmp, S a, S b) {
this.cmp = cmp;
this.baseA = a;
this.baseB = b;
}
/** @return obtain a comparator that uses the cached hash codes. */
public HashedSequenceComparator getComparator() {
return new HashedSequenceComparator(cmp);
}
/** @return wrapper around A that includes cached hash codes. */
public HashedSequence getA() {
if (cachedA == null)
cachedA = wrap(baseA);
return cachedA;
}
/** @return wrapper around B that includes cached hash codes. */
public HashedSequence getB() {
if (cachedB == null)
cachedB = wrap(baseB);
return cachedB;
}
private HashedSequence wrap(S base) {
final int end = base.size();
final int[] hashes = new int[end];
for (int ptr = 0; ptr < end; ptr++)
hashes[ptr] = cmp.hash(base, ptr);
return new HashedSequence(base, hashes);
}
}