panda.tool.esort.KMerge Maven / Gradle / Ivy
package panda.tool.esort;
import java.io.IOException;
import java.util.Comparator;
import java.util.TreeSet;
/**
* K-Merge
* @param object type
*/
public abstract class KMerge {
protected class Segment {
int segmentNo;
T record;
};
protected class Compare implements Comparator {
protected Comparator comparator;
/**
* @return comparator
*/
public Comparator getComparator() {
return comparator;
}
/**
* @param comparator set comparator
*/
public void setComparator(Comparator comparator) {
this.comparator = comparator;
}
/**
* @param s1 segment 1
* @param s2 segment 2
* @return compare result
* @see java.util.Comparator#compare
*/
@SuppressWarnings("unchecked")
public int compare(Segment s1, Segment s2) {
if (comparator != null) {
return comparator.compare(s1.record, s2.record);
}
if (s1.record instanceof Comparable) {
Comparable c = (Comparable)(s1.record);
return c.compareTo(s2.record);
}
return 0;
}
};
private int size;
private TreeSet loserTree;
private Compare compare;
private KMergeIO mergeIO;
/**
* constructor
* @param k size of k
*/
public KMerge(int k) {
size = k;
loserTree = new TreeSet();
compare = new Compare();
}
/**
* @param comparator set comparator
*/
public void setComparator(Comparator comparator) {
compare.setComparator(comparator);
}
/**
* @return mergeIO
*/
public KMergeIO getMergeIO() {
return mergeIO;
}
/**
* @param mergeIO set mergeIO
*/
public void setMergeIO(KMergeIO mergeIO) {
this.mergeIO = mergeIO;
}
/**
* construct tree
* @throws IOException
*/
protected void constructTree() throws IOException {
for (int i = 0; i < size; i++) {
Segment s = new Segment();
s.segmentNo = i;
s.record = read(i);
if (s.record != null) {
loserTree.add(s);
}
}
}
/**
* merge
* @throws IOException if an I/O error occurs
*/
public void merge() throws IOException {
constructTree();
/* while (loserTree.size() > 0) {
Segment s = loserTree.pollFirst();
write(s.record);
s.record = read(s.segmentNo);
if (s.record != null) {
loserTree.add(s);
}
}*/
}
protected abstract T read(int segmentNo) throws IOException;
protected abstract void write(T obj) throws IOException;
}