io.mindmaps.graql.internal.gremlin.Fragment Maven / Gradle / Ivy
/*
* MindmapsDB - A Distributed Semantic Database
* Copyright (C) 2016 Mindmaps Research Ltd
*
* MindmapsDB 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.
*
* MindmapsDB 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 MindmapsDB. If not, see .
*/
package io.mindmaps.graql.internal.gremlin;
import org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal;
import org.apache.tinkerpop.gremlin.structure.Vertex;
import java.util.Optional;
import java.util.function.UnaryOperator;
/**
* represents a graph traversal, with one start point and optionally an end point
*
* A fragment is composed of four things:
*
* - A gremlin traversal function, that takes a gremlin traversal and appends some new gremlin steps
* - A starting variable name, where the gremlin traversal must start from
* - An optional ending variable name, if the gremlin traversal navigates to a new Graql variable
* - A priority, that describes how efficient this traversal is to help with ordering the traversals
*
*
* Variable names refer to Graql variables. Some of these variable names may be randomly-generated UUIDs, such as for
* castings.
*
* A {@code Fragment} is usually contained in a {@code MultiTraversal}, which contains multiple fragments describing
* the different directions the traversal can be followed in, with different starts and ends.
*
* A gremlin traversal is created from a {@code Query} by appending together fragments in order of priority, one from
* each {@code MultiTraversal} describing the {@code Query}.
*/
public interface Fragment extends Comparable {
static Fragment create(UnaryOperator> traversal, FragmentPriority priority, String start) {
return new FragmentImpl(traversal, priority, start);
}
static Fragment create(
UnaryOperator> traversal,
FragmentPriority priority, String start, String end
) {
return new FragmentImpl(traversal, priority, start, end);
}
/**
* @return the MultiTraversal that contains this Fragment
*/
MultiTraversal getMultiTraversal();
/**
* @param multiTraversal the MultiTraversal that contains this Fragment
*/
void setMultiTraversal(MultiTraversal multiTraversal);
/**
* @param traversal the traversal to extend with this Fragment
*/
void applyTraversal(GraphTraversal traversal);
/**
* @return the variable name that this fragment starts from in the query
*/
String getStart();
/**
* @return the variable name that this fragment ends at in the query, if this query has an end variable
*/
Optional getEnd();
/**
* @return the fragment's priority
*/
FragmentPriority getPriority();
}