001    /*
002     $Id: SpreadList.java,v 1.6 2005/07/19 04:41:52 phk 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    package groovy.lang;
047    
048    import java.util.AbstractList;
049    import java.util.List;
050    
051    import org.codehaus.groovy.runtime.InvokerHelper;
052    
053    /**
054     * Spreads a list as individual objects to support the spread operator (*) for lists.
055     * For examples, <pre>
056     *     def fn(a, b, c, d) { return a + b + c + d }
057     *     println fn(1, 2, 3, 4)
058     * 
059     *     def x = [10, 100]
060     *     def y = [1, *x, 1000, *[10000, 100000]]
061     *     assert y == [1, 10, 100, 1000, 10000, 100000]
062     * </pre><br>
063     * 
064     * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
065     * @author Pilho Kim
066     * @version $Revision: 1.6 $
067     */
068    public class SpreadList extends AbstractList {
069    
070        private Object[] contents;
071        private int hashCode;
072    
073        /**
074         * Generator.
075         *
076         * @param contents an array of objects to be converted to a SpreadList
077         */
078        public SpreadList(Object[] contents) {
079            this.contents = contents;
080        }
081    
082        /**
083         * Returns the object in <code>this</code> of the indicated position.
084         *
085         * @param index the indicated position in <code>this</code>
086         */
087        public Object get(int index) {
088            return contents[index];
089        }
090    
091        /**
092         * Returns the size of <code>this</code>.
093         *
094         * @param index the indicated position in <code>this</code>
095         */
096        public int size() {
097            return contents.length;
098        }
099    
100        /**
101         * Compares <code>this</code> with another object.
102         *
103         * @param that another object to be compared with <code>this</code>
104         * @return Returns <code>true</code> if this equals to <code>that</code>, <code>false</code> otherwise
105         */
106        public boolean equals(Object that) {
107            if (that instanceof SpreadList) {
108                return equals((SpreadList) that);
109            }
110            return false;
111        }
112    
113        /**
114         * Compares <code>this</code> with another spreadlist.
115         *
116         * @param that another spreadlist to be compared with <code>this</code>
117         * @return Returns <code>true</code> if this equals to <code>that</code>, <code>false</code> otherwise
118         */
119        public boolean equals(SpreadList that) {
120            if (contents.length == that.contents.length) {
121                for (int i = 0; i < contents.length; i++) {
122                    if (! InvokerHelper.compareEqual(this.contents[i], that.contents[i])) {
123                        return false;
124                    }
125                }
126                return true;
127            }
128            return false;
129        }
130    
131    
132        /**
133         * Returns the hash code of <code>this</code>.
134         *
135         * @return Returns the hash code of <code>this</code>
136         */
137        public int hashCode() {
138            if (hashCode == 0) {
139                for (int i = 0; i < contents.length; i++ ) {
140                    Object value = contents[i];
141                    int hash = (value != null) ? value.hashCode() : 0xbabe;
142                    hashCode ^= hash;
143                }
144                if (hashCode == 0) {
145                    hashCode = 0xbabe;
146                }
147            }
148            return hashCode;
149        }
150    
151        /**
152         * Returns a sublist of <code>this</code> from <code>fromIndex</code> to <code>toIndex</code>.
153         *
154         * @param fromIndex the first index in <code>this</code> to be taken
155         * @param toIndex the last index in <code>this</code> to be taken
156         * @return Returns the sublist of <code>thin</code> in the given scope
157         */
158        public List subList(int fromIndex, int toIndex) {
159            int size = toIndex - fromIndex;
160            Object[] newContent = new Object[size];
161            System.arraycopy(contents, fromIndex, newContent, 0, size);
162            return new SpreadList(newContent);
163        }
164    
165        /**
166         * Returns the string expression of <code>this</code>.
167         *
168         * @return Returns the string expression of <code>this</code>
169         */
170        public String toString() {
171            return "*" + super.toString();
172        }
173    }