russell@unturf.com
0a580b313d
Authors: russell@unturf.com · brackishbert@gmail.com · foxhop.net · TimeHexOn.com Patches, unit tests, benchmarks, whitepaper, and outreach briefs. Public domain — no copyright claimed. Use freely.
52 lines
2.3 KiB
Java
52 lines
2.3 KiB
Java
package net.minecraft.util;
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import com.google.common.collect.HashMultimap;
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import com.google.common.collect.Multimap;
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import java.util.Collection;
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import java.util.HashMap;
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import java.util.HashSet;
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import java.util.Map;
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import java.util.Set;
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import java.util.function.BiConsumer;
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import java.util.function.Consumer;
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/** BEFORE — defective: isCyclic has no visited set — exponential on diamond graphs */
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public class DependencySorter<K, V extends DependencySorter.Entry<K>> {
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private final Map<K, V> contents = new HashMap<>();
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public DependencySorter<K, V> addEntry(K id, V value) {
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this.contents.put(id, value);
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return this;
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}
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private void visitDependenciesAndElement(Multimap<K, K> dependencies, Set<K> alreadyVisited, K id, BiConsumer<K, V> output) {
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if (!alreadyVisited.add(id)) return;
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dependencies.get(id).forEach(dep -> visitDependenciesAndElement(dependencies, alreadyVisited, dep, output));
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V current = this.contents.get(id);
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if (current != null) output.accept(id, current);
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}
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// DEFECT: no visited set — O(E^D) on diamond graphs
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private static <K> boolean isCyclic(Multimap<K, K> directDependencies, K from, K to) {
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Collection<K> dependencies = directDependencies.get(to);
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if (dependencies.contains(from)) return true;
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return dependencies.stream().anyMatch(dep -> isCyclic(directDependencies, from, dep));
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}
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private static <K> void addDependencyIfNotCyclic(Multimap<K, K> directDependencies, K from, K to) {
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if (!isCyclic(directDependencies, from, to)) directDependencies.put(from, to);
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}
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public void orderByDependencies(BiConsumer<K, V> output) {
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HashMultimap<K, K> directDependencies = HashMultimap.create();
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this.contents.forEach((id, value) -> value.visitRequiredDependencies(dep -> addDependencyIfNotCyclic(directDependencies, id, dep)));
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this.contents.forEach((id, value) -> value.visitOptionalDependencies(dep -> addDependencyIfNotCyclic(directDependencies, id, dep)));
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Set<K> alreadyVisited = new HashSet<>();
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this.contents.keySet().forEach(id -> visitDependenciesAndElement(directDependencies, alreadyVisited, id, output));
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}
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public interface Entry<K> {
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void visitRequiredDependencies(Consumer<K> consumer);
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void visitOptionalDependencies(Consumer<K> consumer);
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}
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}
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