001 /*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache License, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 * http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the License for the specific language governing permissions and
015 * limitations under the License.
016 */
017 package org.apache.commons.jexl2.parser;
018
019 import org.apache.commons.jexl2.DebugInfo;
020 import org.apache.commons.jexl2.JexlInfo;
021
022 /**
023 * Base class for parser nodes - holds an 'image' of the token for later use.
024 *
025 * @since 2.0
026 */
027 public abstract class JexlNode extends SimpleNode implements JexlInfo {
028 /** A marker interface for literals.
029 * @param <T> the literal type
030 */
031 public interface Literal<T> {
032 T getLiteral();
033 }
034 /** token value. */
035 public String image;
036
037 public JexlNode(int id) {
038 super(id);
039 }
040
041 public JexlNode(Parser p, int id) {
042 super(p, id);
043 }
044
045 /** {@inheritDoc} */
046 public DebugInfo debugInfo() {
047 JexlNode node = this;
048 while (node != null) {
049 if (node.value instanceof DebugInfo) {
050 return (DebugInfo) node.value;
051 }
052 node = node.jjtGetParent();
053 }
054 return null;
055 }
056
057 /** {@inheritDoc} */
058 public String debugString() {
059 DebugInfo info = debugInfo();
060 return info != null ? info.debugString() : "";
061 }
062
063 /**
064 * Whether this node is a constant node
065 * Its value can not change after the first evaluation and can be cached indefinitely.
066 * @return true if constant, false otherwise
067 */
068 public final boolean isConstant() {
069 return isConstant(this instanceof JexlNode.Literal<?>);
070 }
071
072 protected boolean isConstant(boolean literal) {
073 if (literal) {
074 if (children != null) {
075 for (JexlNode child : children) {
076 if (child instanceof ASTReference) {
077 boolean is = child.isConstant(true);
078 if (!is) {
079 return false;
080 }
081 } else if (child instanceof ASTMapEntry) {
082 boolean is = child.isConstant(true);
083 if (!is) {
084 return false;
085 }
086 } else if (!child.isConstant()) {
087 return false;
088 }
089 }
090 }
091 return true;
092 }
093 return false;
094 }
095 }