forked from plusone/plusone-commons
40 lines
1.6 KiB
Java
40 lines
1.6 KiB
Java
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package xyz.zhouxy.plusone.commons.util;
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import java.util.Collection;
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import java.util.List;
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import java.util.Map;
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import java.util.Optional;
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import java.util.function.BiConsumer;
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import java.util.function.Function;
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import java.util.stream.Collectors;
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public class TreeBuilder<T, TIdentity> {
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private final Collection<T> nodes;
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private final Function<T, TIdentity> identityGetter;
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private final Function<T, Optional<TIdentity>> parentIdentityGetter;
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private final BiConsumer<T, T> addChildrenMethod;
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public TreeBuilder(Collection<T> nodes, Function<T, TIdentity> identityGetter,
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Function<T, Optional<TIdentity>> parentIdentityGetter, BiConsumer<T, T> addChildren) {
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this.nodes = nodes;
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this.identityGetter = identityGetter;
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this.parentIdentityGetter = parentIdentityGetter;
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this.addChildrenMethod = addChildren;
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}
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public List<T> buildTree() {
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Map<TIdentity, T> identityNodeMap = MoreCollections.toHashMap(nodes, identityGetter);
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List<T> result = this.nodes.stream()
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.filter(node -> !this.parentIdentityGetter.apply(node).isPresent())
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.collect(Collectors.toList());
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for (T node : this.nodes) {
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Optional<TIdentity> parentIdentity = parentIdentityGetter.apply(node);
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if (parentIdentity.isPresent() && identityNodeMap.containsKey(parentIdentity.get())) {
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T parentNode = identityNodeMap.get(parentIdentity.get());
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addChildrenMethod.accept(parentNode, node);
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}
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}
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return result;
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}
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}
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