View Javadoc

1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * The ASF licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *      http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.apache.commons.jexl2.parser;
18  
19  import org.apache.commons.jexl2.DebugInfo;
20  import org.apache.commons.jexl2.JexlInfo;
21  
22  /**
23   * Base class for parser nodes - holds an 'image' of the token for later use.
24   *
25   * @since 2.0
26   */
27  public abstract class JexlNode extends SimpleNode implements JexlInfo {
28      /** A marker interface for literals.
29       * @param <T> the literal type
30       */
31      public interface Literal<T> {
32          T getLiteral();
33      }
34      /** token value. */
35      public String image;
36  
37      public JexlNode(int id) {
38          super(id);
39      }
40  
41      public JexlNode(Parser p, int id) {
42          super(p, id);
43      }
44  
45      /** {@inheritDoc} */
46      public DebugInfo debugInfo() {
47          JexlNode node = this;
48          while (node != null) {
49              if (node.value instanceof DebugInfo) {
50                  return (DebugInfo) node.value;
51              }
52              node = node.jjtGetParent();
53          }
54          return null;
55      }
56  
57      /** {@inheritDoc} */
58      public String debugString() {
59          DebugInfo info = debugInfo();
60          return info != null ? info.debugString() : "";
61      }
62  
63      /**
64       * Whether this node is a constant node
65       * Its value can not change after the first evaluation and can be cached indefinitely.
66       * @return true if constant, false otherwise
67       */
68      public final boolean isConstant() {
69          return isConstant(this instanceof JexlNode.Literal<?>);
70      }
71  
72      protected boolean isConstant(boolean literal) {
73          if (literal) {
74              if (children != null) {
75                  for (JexlNode child : children) {
76                      if (child instanceof ASTReference) {
77                          boolean is = child.isConstant(true);
78                          if (!is) {
79                              return false;
80                          }
81                      } else if (child instanceof ASTMapEntry) {
82                          boolean is = child.isConstant(true);
83                          if (!is) {
84                              return false;
85                          }
86                      } else if (!child.isConstant()) {
87                          return false;
88                      }
89                  }
90              }
91              return true;
92          }
93          return false;
94      }
95  }