Production


1   /*
2    * Production.java
3    *
4    * This library is free software; you can redistribute it and/or
5    * modify it under the terms of the GNU Lesser General Public License
6    * as published by the Free Software Foundation; either version 2.1
7    * of the License, or (at your option) any later version.
8    *
9    * This library is distributed in the hope that it will be useful,
10   * but WITHOUT ANY WARRANTY; without even the implied warranty of
11   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   * Lesser General Public License for more details.
13   *
14   * You should have received a copy of the GNU Lesser General Public
15   * License along with this library; if not, write to the Free
16   * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
17   * MA 02111-1307, USA.
18   *
19   * Copyright (c) 2003-2005 Per Cederberg. All rights reserved.
20   */
21  
22  package net.percederberg.grammatica.parser;
23  
24  import java.util.ArrayList  ;
25  
26  /**
27   * A production node. This class represents a grammar production (i.e.
28   * a list of child nodes) in a parse tree. The productions are created
29   * by a parser, that adds children a according to a set of production
30   * patterns (i.e. grammar rules).
31   *
32   * @author   Per Cederberg, <per at percederberg dot net>
33   * @version  1.1
34   */
35  public class Production extends Node {
36  
37      /**
38       * The production pattern used for this production.
39       */
40      private ProductionPattern pattern;
41  
42      /**
43       * The child nodes.
44       */
45      private ArrayList   children;
46  
47      /**
48       * Creates a new production node.
49       *
50       * @param pattern        the production pattern
51       */
52      public Production(ProductionPattern pattern) {
53          this.pattern = pattern;
54          this.children = new ArrayList  ();
55      }
56  
57      /**
58       * Checks if this node is hidden, i.e. if it should not be visible
59       * outside the parser.
60       *
61       * @return true if the node should be hidden, or
62       *         false otherwise
63       */
64      boolean isHidden() {
65          return pattern.isSynthetic();
66      }
67  
68      /**
69       * Returns the production pattern for this production.
70       *
71       * @return the production pattern
72       */
73      public ProductionPattern getPattern() {
74          return pattern;
75      }
76  
77      /**
78       * Returns the production (pattern) id. This value is set as a
79       * unique identifier when creating the production pattern to
80       * simplify later identification.
81       *
82       * @return the production id
83       */
84      public int getId() {
85          return pattern.getId();
86      }
87  
88      /**
89       * Returns the production node name.
90       *
91       * @return the production node name
92       */
93      public String   getName() {
94          return pattern.getName();
95      }
96  
97      /**
98       * Returns the number of child nodes.
99       *
100      * @return the number of child nodes
101      */
102     public int getChildCount() {
103         return children.size();
104     }
105 
106     /**
107      * Returns the child node with the specified index.
108      *
109      * @param index          the child index, 0 <= index < count
110      *
111      * @return the child node found, or
112      *         null if index out of bounds
113      */
114     public Node getChildAt(int index) {
115         if (index < 0 || index >= children.size()) {
116             return null;
117         } else {
118             return (Node) children.get(index);
119         }
120     }
121 
122     /**
123      * Adds a child node. The node will be added last in the list of
124      * children.
125      *
126      * @param child          the child node to add
127      */
128     public void addChild(Node child) {
129         if (child != null) {
130             child.setParent(this);
131             children.add(child);
132         }
133     }
134 
135     /**
136      * Returns a string representation of this production.
137      *
138      * @return a string representation of this production
139      */
140     public String   toString() {
141         StringBuffer    buffer = new StringBuffer  ();
142 
143         buffer.append(pattern.getName());
144         buffer.append('(');
145         buffer.append(pattern.getId());
146         buffer.append(')');
147 
148         return buffer.toString();
149     }
150 }
151
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