com.github.akurilov.commons.collection.TreeUtil Maven / Gradle / Ivy
package com.github.akurilov.commons.collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
public interface TreeUtil {
/**
Deep copy the tree implemented as map of maps/leafs
@param srcTree the source tree
@return the tree copy
*/
@SuppressWarnings("unchecked")
static Map copyTree(final Map srcTree) {
final Map dstTree = new HashMap<>(srcTree.size());
srcTree.forEach(
(k, v) -> dstTree.put(k, v instanceof Map ? copyTree((Map) v) : v)
);
return dstTree;
}
@SuppressWarnings("unchecked")
static Map addBranches(
final Map dst, final Map src
) {
src.forEach(
(k, v) -> {
if(v instanceof Map) {
final Object dstNode = dst.get(k);
if(dstNode instanceof Map) {
addBranches((Map) dstNode, (Map) v);
} else {
dst.put(k, v);
}
} else {
dst.put(k, v);
}
}
);
return dst;
}
/**
Merge the tree by reducing the given forest. Any leaf in any next tree is added to the
resulting tree, overwriting already existing leaf if any
@param forest the given forest (list of trees)
@return the resulting tree (may be empty)
*/
static Map reduceForest(final List> forest) {
return forest
.stream()
.reduce(TreeUtil::addBranches)
.orElseGet(Collections::emptyMap);
}
}