/*
* xtc - The eXTensible Compiler
* Copyright (C) 2005-2007 Robert Grimm
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* version 2 as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,
* USA.
*/
package xtc.parser;
import java.util.ArrayList;
import xtc.Constants;
import xtc.tree.Attribute;
import xtc.util.Runtime;
/**
* Visitor to detect productions that can be treated as transient.
*
* <p />Note that this visitor requires that a grammar's productions
* have been {@link ReferenceCounter reference counted}. Further note
* that this visitor assumes that the entire grammar is contained in a
* single module.
*
* @author Robert Grimm
* @version $Revision: 1.22 $
*/
public class TransientMarker extends GrammarVisitor {
/**
* Create a new transient marker.
*
* @param runtime The runtime.
* @param analyzer The analyzer utility.
*/
public TransientMarker(Runtime runtime, Analyzer analyzer) {
super(runtime, analyzer);
}
/**
* Visit the specified grammar.
*
* @param m The grammar module.
* @return <code>Boolean.TRUE</code> if the grammar has been modified,
* otherwise <code>Boolean.FALSE</code>.
*/
public Object visit(Module m) {
// Initialize the per-grammar state.
analyzer.register(this);
analyzer.init(m);
// Process the productions.
boolean changed = false;
for (Production p : m.productions) {
MetaData md = (MetaData)p.getProperty(Properties.META_DATA);
if ((1 >= md.usageCount) &&
(! p.hasAttribute(Constants.ATT_TRANSIENT)) &&
(! p.hasAttribute(Constants.ATT_INLINE)) &&
(! p.hasAttribute(Constants.ATT_MEMOIZED))) {
if (runtime.test("optionVerbose")) {
System.err.println("[Marking " + p.qName + " as transient]");
}
if (null == p.attributes) {
p.attributes = new ArrayList<Attribute>(1);
}
p.attributes.add(Constants.ATT_TRANSIENT);
changed = true;
}
}
// Done.
return Boolean.valueOf(changed);
}
}