CharEscapeTransformation.java

/*
 * Copyright (C) 2011 eXo Platform SAS.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */

package org.exoplatform.web.controller.router;

import org.exoplatform.web.controller.regexp.RENode;
import org.exoplatform.web.controller.regexp.REVisitor;

/**
 * The route escaper transformer a regular expression with the following rules:
 * <ul>
 * <li>substitute any char occurence of the source <i>s</i> by the destination <i>d</i></li>
 * <li>replace the <i>any</i> by the negated destination character <i>[^]</i></li>
 * <li>append <i>&&[^s]</i> to any top character class</li>
 * </ul>
 *
 * A few examples with <i>/</i> replaced by <i>_</i>:
 *
 * <ul>
 * <li><i>/</i> becomes <i>_</i></li>
 * <li><i>.</i> becomes <i>[^/]</i></li>
 * <li><i>[a/]</i> becomes <i>[a_&[^/]]</i></li>
 * <li><i>[,-1]</i> becomes <i>[,-.0-1_&&[^/]]</i></li>
 * </ul>
 *
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
class CharEscapeTransformation extends REVisitor<MalformedRouteException> {

    /** . */
    private final char src;

    /** . */
    private final char dst;

    public CharEscapeTransformation(char src, char dst) {
        this.src = src;
        this.dst = dst;
    }

    @Override
    protected void visit(RENode.Char expr) throws MalformedRouteException {
        if (expr.getValue() == src) {
            expr.setValue(dst);
        }
    }

    @Override
    protected void visit(RENode.Any expr) throws MalformedRouteException {
        RENode.CharacterClass repl = new RENode.CharacterClass(new RENode.CharacterClassExpr.Not(
                new RENode.CharacterClassExpr.Char('/')));
        repl.setQuantifier(expr.getQuantifier());
        expr.replaceBy(repl);
    }

    @Override
    protected void visit(RENode.CharacterClass expr) throws MalformedRouteException {
        RENode.CharacterClassExpr ccExpr = expr.getExpr();
        ccExpr = ccExpr.replace(src, dst);
        // RENode.CharacterClassExpr.And ccRepl = new RENode.CharacterClassExpr.And(null, new RENode.CharacterClassExpr.Not(new
        // RENode.CharacterClassExpr.Char('/')));
        // ccExpr.replaceBy(ccRepl);
        // ccRepl.setLeft(ccExpr);
    }
}