001 /* 002 $Id: Reduction.java,v 1.3 2005/04/12 15:04:59 jstrachan Exp $ 003 004 Copyright 2003 (C) James Strachan and Bob Mcwhirter. All Rights Reserved. 005 006 Redistribution and use of this software and associated documentation 007 ("Software"), with or without modification, are permitted provided 008 that the following conditions are met: 009 010 1. Redistributions of source code must retain copyright 011 statements and notices. Redistributions must also contain a 012 copy of this document. 013 014 2. Redistributions in binary form must reproduce the 015 above copyright notice, this list of conditions and the 016 following disclaimer in the documentation and/or other 017 materials provided with the distribution. 018 019 3. The name "groovy" must not be used to endorse or promote 020 products derived from this Software without prior written 021 permission of The Codehaus. For written permission, 022 please contact info@codehaus.org. 023 024 4. Products derived from this Software may not be called "groovy" 025 nor may "groovy" appear in their names without prior written 026 permission of The Codehaus. "groovy" is a registered 027 trademark of The Codehaus. 028 029 5. Due credit should be given to The Codehaus - 030 http://groovy.codehaus.org/ 031 032 THIS SOFTWARE IS PROVIDED BY THE CODEHAUS AND CONTRIBUTORS 033 ``AS IS'' AND ANY EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT 034 NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND 035 FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 036 THE CODEHAUS OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, 037 INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 038 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 039 SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 040 HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 041 STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 042 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 043 OF THE POSSIBILITY OF SUCH DAMAGE. 044 045 */ 046 047 package org.codehaus.groovy.syntax; 048 049 import org.codehaus.groovy.GroovyBugError; 050 import org.codehaus.groovy.syntax.Token; 051 052 import java.util.List; 053 import java.util.ArrayList; 054 import java.util.Collections; 055 056 057 /** 058 * A syntax reduction, produced by the <code>Parser</code>. 059 * 060 * @see Parser 061 * @see Token 062 * @see CSTNode 063 * @see Types 064 * 065 * @author <a href="mailto:bob@werken.com">bob mcwhirter</a> 066 * @author <a href="mailto:cpoirier@dreaming.org">Chris Poirier</a> 067 * 068 * @version $Id: Reduction.java,v 1.3 2005/04/12 15:04:59 jstrachan Exp $ 069 */ 070 071 public class Reduction extends CSTNode 072 { 073 public static final Reduction EMPTY = new Reduction(); 074 075 076 //--------------------------------------------------------------------------- 077 // INITIALIZATION AND SUCH 078 079 private List elements = null; // The set of child nodes 080 private boolean marked = false; // Used for completion marking by some parts of the parser 081 082 083 /** 084 * Initializes the <code>Reduction</code> with the specified root. 085 */ 086 087 public Reduction( Token root ) 088 { 089 elements = new ArrayList(); 090 set( 0, root ); 091 } 092 093 094 /** 095 * Initializes the <code>Reduction</code> to empty. 096 */ 097 098 private Reduction() 099 { 100 elements = Collections.EMPTY_LIST; 101 } 102 103 104 /** 105 * Creates a new <code>Reduction</code> with <code>Token.NULL</code> 106 * as it's root. 107 */ 108 109 public static Reduction newContainer() 110 { 111 return new Reduction( Token.NULL ); 112 } 113 114 115 116 117 //--------------------------------------------------------------------------- 118 // MEMBER ACCESS 119 120 121 /** 122 * Returns true if the node is completely empty (no root, even). 123 */ 124 125 public boolean isEmpty() 126 { 127 return size() == 0; 128 } 129 130 131 132 /** 133 * Returns the number of elements in the node. 134 */ 135 136 public int size() 137 { 138 return elements.size(); 139 } 140 141 142 143 /** 144 * Returns the specified element, or null. 145 */ 146 147 public CSTNode get( int index ) 148 { 149 CSTNode element = null; 150 151 if( index < size() ) 152 { 153 element = (CSTNode)elements.get( index ); 154 } 155 156 return element; 157 } 158 159 160 161 /** 162 * Returns the root of the node, the Token that indicates it's 163 * type. Returns null if there is no root (usually only if the 164 * node is a placeholder of some kind -- see isEmpty()). 165 */ 166 167 public Token getRoot() 168 { 169 if( size() > 0 ) 170 { 171 return (Token)elements.get(0); 172 } 173 else 174 { 175 return null; 176 } 177 } 178 179 180 181 /** 182 * Marks the node a complete expression. 183 */ 184 185 public void markAsExpression() 186 { 187 marked = true; 188 } 189 190 191 192 /** 193 * Returns true if the node is a complete expression. 194 */ 195 196 public boolean isAnExpression() 197 { 198 if( isA(Types.COMPLEX_EXPRESSION) ) 199 { 200 return true; 201 } 202 203 return marked; 204 } 205 206 207 208 209 //--------------------------------------------------------------------------- 210 // OPERATIONS 211 212 213 /** 214 * Adds an element to the node. 215 */ 216 217 public CSTNode add( CSTNode element ) 218 { 219 return set( size(), element ); 220 } 221 222 223 224 /** 225 * Sets an element in at the specified index. 226 */ 227 228 public CSTNode set( int index, CSTNode element ) 229 { 230 231 if( elements == null ) 232 { 233 throw new GroovyBugError( "attempt to set() on a EMPTY Reduction" ); 234 } 235 236 if( index == 0 && !(element instanceof Token) ) 237 { 238 239 // 240 // It's not the greatest of design that the interface allows this, but it 241 // is a tradeoff with convenience, and the convenience is more important. 242 243 throw new GroovyBugError( "attempt to set() a non-Token as root of a Reduction" ); 244 } 245 246 247 // 248 // Fill slots with nulls, if necessary. 249 250 int count = elements.size(); 251 if( index >= count ) 252 { 253 for( int i = count; i <= index; i++ ) 254 { 255 elements.add( null ); 256 } 257 } 258 259 // 260 // Then set in the element. 261 262 elements.set( index, element ); 263 264 return element; 265 } 266 267 268 269 /** 270 * Removes a node from the <code>Reduction</code>. You cannot remove 271 * the root node (index 0). 272 */ 273 274 public CSTNode remove( int index ) 275 { 276 if( index < 1 ) 277 { 278 throw new GroovyBugError( "attempt to remove() root node of Reduction" ); 279 } 280 281 return (CSTNode)elements.remove( index ); 282 } 283 284 285 286 /** 287 * Creates a <code>Reduction</code> from this node. Returns self if the 288 * node is already a <code>Reduction</code>. 289 */ 290 291 public Reduction asReduction() 292 { 293 return this; 294 } 295 296 } 297