188 lines
6.1 KiB
Java
188 lines
6.1 KiB
Java
/*
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* WorldEdit, a Minecraft world manipulation toolkit
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* Copyright (C) sk89q <http://www.sk89q.com>
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* Copyright (C) WorldEdit team and contributors
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*
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* This program is free software: you can redistribute it and/or modify it
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* under the terms of the GNU Lesser General Public License as published by the
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* Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
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* for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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package com.sk89q.worldedit.function.visitor;
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import static com.google.common.base.Preconditions.checkNotNull;
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import java.util.ArrayDeque;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.HashSet;
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import java.util.List;
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import java.util.Queue;
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import java.util.Set;
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import com.sk89q.worldedit.BlockVector;
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import com.sk89q.worldedit.Vector;
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import com.sk89q.worldedit.WorldEditException;
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import com.sk89q.worldedit.function.RegionFunction;
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import com.sk89q.worldedit.function.operation.Operation;
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import com.sk89q.worldedit.function.operation.Operations;
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import com.sk89q.worldedit.function.operation.RunContext;
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/**
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* Performs a breadth-first search starting from points added with
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* {@link #visit(com.sk89q.worldedit.Vector)}. The search continues
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* to a certain adjacent point provided that the method
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* {@link #isVisitable(com.sk89q.worldedit.Vector, com.sk89q.worldedit.Vector)}
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* returns true for that point.
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*
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* <p>As an abstract implementation, this class can be used to implement
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* functionality that starts at certain points and extends outward from
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* those points.</p>
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*/
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public abstract class BreadthFirstSearch implements Operation {
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private final RegionFunction function;
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private final Queue<BlockVector> queue = new ArrayDeque<BlockVector>();
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private final Set<BlockVector> visited = new HashSet<BlockVector>();
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private final List<Vector> directions = new ArrayList<Vector>();
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private int affected = 0;
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/**
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* Create a new instance.
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*
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* @param function the function to apply to visited blocks
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*/
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protected BreadthFirstSearch(final RegionFunction function) {
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checkNotNull(function);
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this.function = function;
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addAxes();
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}
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/**
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* Get the list of directions will be visited.
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*
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* <p>Directions are {@link com.sk89q.worldedit.Vector}s that determine
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* what adjacent points area available. Vectors should not be
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* unit vectors. An example of a valid direction is
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* {@code new Vector(1, 0, 1)}.</p>
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*
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* <p>The list of directions can be cleared.</p>
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*
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* @return the list of directions
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*/
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protected Collection<Vector> getDirections() {
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return directions;
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}
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/**
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* Add the directions along the axes as directions to visit.
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*/
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protected void addAxes() {
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directions.add(new Vector(0, -1, 0));
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directions.add(new Vector(0, 1, 0));
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directions.add(new Vector(-1, 0, 0));
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directions.add(new Vector(1, 0, 0));
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directions.add(new Vector(0, 0, -1));
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directions.add(new Vector(0, 0, 1));
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}
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/**
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* Add the diagonal directions as directions to visit.
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*/
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protected void addDiagonal() {
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directions.add(new Vector(1, 0, 1));
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directions.add(new Vector(-1, 0, -1));
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directions.add(new Vector(1, 0, -1));
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directions.add(new Vector(-1, 0, 1));
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}
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/**
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* Add the given location to the list of locations to visit, provided
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* that it has not been visited. The position passed to this method
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* will still be visited even if it fails
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* {@link #isVisitable(com.sk89q.worldedit.Vector, com.sk89q.worldedit.Vector)}.
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*
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* <p>This method should be used before the search begins, because if
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* the position <em>does</em> fail the test, and the search has already
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* visited it (because it is connected to another root point),
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* the search will mark the position as "visited" and a call to this
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* method will do nothing.</p>
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*
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* @param position the position
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*/
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public void visit(final Vector position) {
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final BlockVector blockVector = position.toBlockVector();
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if (!visited.contains(blockVector)) {
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queue.add(blockVector);
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visited.add(blockVector);
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}
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}
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/**
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* Try to visit the given 'to' location.
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*
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* @param from the origin block
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* @param to the block under question
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*/
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private void visit(final Vector from, final Vector to) {
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final BlockVector blockVector = to.toBlockVector();
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if (!visited.contains(blockVector)) {
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visited.add(blockVector);
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if (isVisitable(from, to)) {
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queue.add(blockVector);
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}
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}
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}
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/**
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* Return whether the given 'to' block should be visited, starting from the
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* 'from' block.
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*
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* @param from the origin block
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* @param to the block under question
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* @return true if the 'to' block should be visited
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*/
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protected abstract boolean isVisitable(final Vector from, final Vector to);
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/**
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* Get the number of affected objects.
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*
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* @return the number of affected
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*/
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public int getAffected() {
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return affected;
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}
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@Override
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public Operation resume(final RunContext run) throws WorldEditException {
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Vector position;
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while ((position = queue.poll()) != null) {
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if (function.apply(position)) {
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affected++;
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}
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for (final Vector dir : directions) {
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visit(position, position.add(dir));
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}
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}
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return null;
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}
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@Override
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public void cancel() {}
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public static Class<?> inject() {
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return Operations.class;
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}
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}
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