001    /*
002     $Id: VariableScope.java,v 1.5 2005/04/14 08:46:18 blackdrag 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,
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043     OF THE POSSIBILITY OF SUCH DAMAGE.
044    
045     */
046    package org.codehaus.groovy.ast;
047    
048    import java.util.ArrayList;
049    import java.util.HashSet;
050    import java.util.Iterator;
051    import java.util.List;
052    import java.util.Set;
053    
054    /**
055     * Represents a variable scope. This is primarily used to determine variable sharing
056     * across method and closure boundaries.
057     *
058     * @author <a href="mailto:james@coredevelopers.net">James Strachan</a>
059     * @version $Revision: 1.5 $
060     */
061    public class VariableScope  {
062            static int i = 0;
063        private Set declaredVariables = new HashSet(); // contain var names
064        private Set referencedVariables = new HashSet(); // contain var names
065    
066        /**
067         *  br contain vars really declared and defined in the current scope.
068         * to be filler later by comparing with parent scope all the ancestors.
069         */
070        private Set varsDeclaredHere = null;
071        // each var should really have a scope decarator
072        // for now it's a naked name, which has the problem of name clashing with parameters
073        // and ancesters' vars with the same name. Effectively this means we cannot have a
074        // local var defined with the same name with any parameters or vars in any of the
075        // ancestors.
076        // we need to reengineer the scope and vars framework.
077    
078        private VariableScope parent;
079        private List children = new ArrayList();
080        String name = null;
081    
082        public VariableScope() {
083            name = String.valueOf(i++);  // should give it a more meaningful name, w/ class, methed, blockstatement etc.
084        }
085    
086        public VariableScope(VariableScope parent) {
087            this.parent = parent;
088            parent.children.add(this);
089            name = String.valueOf(i);
090        }
091    
092        public Set getDeclaredVariables() {
093            return declaredVariables;
094        }
095    
096        public Set getReferencedVariables() {
097            return referencedVariables;
098        }
099    
100        /**
101         * @return all the child scopes
102         */
103        public List getChildren() {
104            return children;
105        }
106    
107        /**
108         * Creates a composite variable scope combining all the variable references
109         * and declarations from all the child scopes not including this scope
110         *
111         * @return
112         */
113        public VariableScope createCompositeChildScope() {
114            VariableScope answer = new VariableScope();
115            for (Iterator iter = children.iterator(); iter.hasNext(); ) {
116                answer.appendRecursive((VariableScope) iter.next());
117            }
118            answer.parent = this;  // shall we cache this for better performance?
119            return answer;
120        }
121    
122        /**
123         * Creates a scope including this scope and all nested scopes combined together
124         *
125         * @return
126         */
127        public VariableScope createRecursiveChildScope() {
128            VariableScope answer = createCompositeChildScope();
129            answer.referencedVariables.addAll(referencedVariables);
130            answer.declaredVariables.addAll(declaredVariables);
131            return answer;
132        }
133    
134        /**
135         * Creates a scope including this scope and all parent scopes combined together
136         *
137         * @return
138         */
139        public VariableScope createRecursiveParentScope() {
140            VariableScope answer = new VariableScope();
141            VariableScope node = this;
142            do {
143                answer.append(node);
144                node = node.parent;
145            }
146            while (node != null);
147            return answer;
148        }
149    
150        /**
151         * Appends all of the references and declarations from the given scope
152         * to this one
153         *
154         * @param scope
155         */
156        protected void append(VariableScope scope) {
157            referencedVariables.addAll(scope.referencedVariables);
158            declaredVariables.addAll(scope.declaredVariables);
159        }
160    
161        /**
162         * Appends all of the references and declarations from the given scope
163         * and all its children to this one
164         *
165         * @param scope
166         */
167        protected void appendRecursive(VariableScope scope) {
168            append(scope);
169    
170            // now lets traverse the children
171            for (Iterator iter = scope.children.iterator(); iter.hasNext(); ) {
172                appendRecursive((VariableScope) iter.next());
173            }
174         }
175    
176        /*
177         * compute the real declares in the current scope
178         * @author bran
179         *
180         * To change the template for this generated type comment go to
181         * Window - Preferences - Java - Code Generation - Code and Comments
182         */
183        public void computeRealDeclares() {
184            if (this.varsDeclaredHere == null) this.varsDeclaredHere = new HashSet();
185            Set decls = this.declaredVariables;
186            for (Iterator iter = decls.iterator(); iter.hasNext();) {
187                            String var = (String) iter.next();
188                            // simplistic way of determing declares by simple name matching
189                            if (!createRecursiveParentScope().getDeclaredVariables().contains(var)) {
190                                    this.varsDeclaredHere.add(var);
191                            }
192                    }
193        }
194            /**
195             * @return Returns the varsDeclaredHere.
196             */
197            public Set getVarsDeclaredHere() {
198                    if (this.varsDeclaredHere == null) computeRealDeclares();
199                    return varsDeclaredHere;
200            }
201            /**
202             * @param varsDeclaredHere The varsDeclaredHere to set.
203             */
204            public void setVarsDeclaredHere(Set varsDeclaredHere) {
205                    this.varsDeclaredHere = varsDeclaredHere;
206            }
207        
208        public VariableScope getParent() {
209            return parent;
210        }
211    }