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Graph Database API for Neo4j.
There is a newer version: 5.25.1
/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see .
 */
package org.neo4j.graphdb;

import static org.neo4j.graphdb.Direction.BOTH;

import java.util.function.Predicate;
import org.neo4j.annotations.api.PublicApi;
import org.neo4j.graphdb.impl.OrderedByTypeExpander;
import org.neo4j.graphdb.impl.StandardExpander;

/**
 * A fluent builder for creating specialized {@link PathExpander path expanders}.
 * 
 * See {@link PathExpanders} for a catalog of common expanders.
 */
@PublicApi
public class PathExpanderBuilder {
    /**
     * A {@link PathExpanderBuilder} that follows no relationships. You start with this and use
     * {@link #add(RelationshipType, Direction)} to form a restrictive PathExpander with just a few expansion rules
     * in it.
     *
     * @return a {@link PathExpanderBuilder} that follows no relationships
     */
    public static PathExpanderBuilder empty() {
        return new PathExpanderBuilder(StandardExpander.EMPTY);
    }

    /**
     * A {@link PathExpanderBuilder} that follows no relationships. You start with this and use
     * {@link #add(RelationshipType, Direction)} to form a restrictive PathExpander with just a few expansion rules
     * in it.
     *
     * @return a {@link PathExpanderBuilder} that follows no relationships
     */
    public static PathExpanderBuilder emptyOrderedByType() {
        return new PathExpanderBuilder(new OrderedByTypeExpander());
    }

    /**
     * A {@link PathExpanderBuilder} that is seeded with all possible relationship types in {@link Direction#BOTH both
     * directions}. You start with this and {@link #remove(RelationshipType) remove types} to form a permissive
     * {@link PathExpander} with just a few exceptions in it.
     *
     * @return a {@link PathExpanderBuilder} that is seeded with all possible relationship types in {@link Direction#BOTH both
     * directions}
     */
    public static PathExpanderBuilder allTypesAndDirections() {
        return new PathExpanderBuilder(StandardExpander.DEFAULT);
    }

    /**
     * A {@link PathExpanderBuilder} seeded with all possible types but restricted to {@code direction}. You start
     * with this and {@link #remove(RelationshipType) remove types} to form a permissive {@link PathExpander} with
     * just a few exceptions in it.
     *
     * @param direction The direction you want to restrict expansions to
     * @return a {@link PathExpanderBuilder} seeded with all possible types but restricted to {@code direction}.
     */
    public static PathExpanderBuilder allTypes(Direction direction) {
        return new PathExpanderBuilder(StandardExpander.create(direction));
    }

    /**
     * Add a pair of {@code type} and {@link Direction#BOTH} to the PathExpander configuration.
     *
     * @param type the type to add for expansion in both directions
     * @return a {@link PathExpanderBuilder} with the added expansion of {@code type} relationships in both directions
     */
    public PathExpanderBuilder add(RelationshipType type) {
        return add(type, BOTH);
    }

    /**
     * Add a pair of {@code type} and {@code direction} to the PathExpander configuration.
     *
     * @param type the type to add for expansion
     * @param direction the direction to restrict the expansion to
     * @return a {@link PathExpanderBuilder} with the added expansion of {@code type} relationships in the given direction
     */
    public PathExpanderBuilder add(RelationshipType type, Direction direction) {
        return new PathExpanderBuilder(expander.add(type, direction));
    }

    /**
     * Remove expansion of {@code type} in any direction from the PathExpander configuration.
     * 
     * Example: {@code PathExpanderBuilder.allTypesAndDirections().remove(type).add(type, Direction.INCOMING)}
     * would restrict the {@link PathExpander} to only follow {@code Direction.INCOMING} relationships for {@code
     * type} while following any other relationship type in either direction.
     *
     * @param type the type to remove from expansion
     * @return a {@link PathExpanderBuilder} with expansion of {@code type} relationships removed
     */
    public PathExpanderBuilder remove(RelationshipType type) {
        return new PathExpanderBuilder(expander.remove(type));
    }

    /**
     * Adds a {@link Node} filter.
     *
     * @param filter a Predicate for filtering nodes.
     * @return a {@link PathExpanderBuilder} with the added node filter.
     */
    public PathExpanderBuilder addNodeFilter(Predicate filter) {
        return new PathExpanderBuilder(expander.addNodeFilter(filter));
    }

    /**
     * Adds a {@link Relationship} filter.
     *
     * @param filter a Predicate for filtering relationships.
     * @return a {@link PathExpanderBuilder} with the added relationship filter.
     */
    public PathExpanderBuilder addRelationshipFilter(Predicate filter) {
        return new PathExpanderBuilder(expander.addRelationshipFilter(filter));
    }

    /**
     * Produce a {@link PathExpander} from the configuration you have built up.
     *
     * @param  the type of the object holding the state
     * @return a PathExpander produced from the configuration you have built up
     */
    @SuppressWarnings("unchecked")
    public  PathExpander build() {
        return expander;
    }

    private final StandardExpander expander;

    private PathExpanderBuilder(StandardExpander expander) {
        this.expander = expander;
    }
}