/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.tinkerpop.gremlin.process.traversal;
import java.util.HashMap;
import java.util.Map;
/**
* Bindings are used to associate a variable with a value.
* They enable the creation of {@link org.apache.tinkerpop.gremlin.process.traversal.Bytecode.Binding} arguments in {@link Bytecode}.
* Use the Bindings instance when defining a binding via {@link Bindings#of(String, Object)}.
* For instance:
* <p>
* <code>
* b = Bindings.instance()
* g = graph.traversal()
* g.V().out(b.of("a","knows"))
* // bindings can be reused over and over
* g.V().out("knows").in(b.of("a","created"))
* </code>
* </p>
*
* @author Marko A. Rodriguez (http://markorodriguez.com)
*/
public final class Bindings {
private static final Bindings INSTANCE = new Bindings();
private static final ThreadLocal<Map<Object, String>> MAP = new ThreadLocal<>();
/**
* @deprecated As of release 3.2.4, replaced by {@link Bindings#instance()}.
*/
@Deprecated
public Bindings() {
}
public <V> V of(final String variable, final V value) {
Map<Object, String> map = MAP.get();
if (null == map) {
map = new HashMap<>();
MAP.set(map);
}
map.put(value, variable);
return value;
}
protected static <V> String getBoundVariable(final V value) {
final Map<Object, String> map = MAP.get();
return null == map ? null : map.get(value);
}
protected static void clear() {
final Map<Object, String> map = MAP.get();
if (null != map)
map.clear();
}
public static Bindings instance() {
return INSTANCE;
}
@Override
public String toString() {
return "bindings[" + Thread.currentThread().getName() + "]";
}
}