| /* |
| * 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 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<>(); |
| |
| private 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() + "]"; |
| } |
| } |