RERenderer.java

/*
 * Copyright (C) 2010 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.regexp;

import java.io.IOException;


/**
 * Renders a {@link RENode} to its pattern representation.
 *
 * @author <a href="mailto:julien.viet@exoplatform.com">Julien Viet</a>
 * @version $Revision$
 */
public class RERenderer extends REVisitor<IOException> {

    public static <A extends Appendable> A render(RENode re, A appendable) throws IOException, NullPointerException {
        if (re == null) {
            throw new NullPointerException("No null disjunction accepted");
        }
        if (appendable == null) {
            throw new NullPointerException("No null appendable accepted");
        }

        //
        RERenderer renderer = new RERenderer(appendable);

        //
        re.accept(renderer);

        //
        return appendable;
    }

    /** . */
    private final Appendable appendable;

    public RERenderer(Appendable appendable) {
        this.appendable = appendable;
    }

    protected void visit(RENode.Disjunction disjunction) throws IOException, NullPointerException {
        RENode.Alternative alternative = disjunction.getAlternative();
        if (alternative != null) {
            alternative.accept(this);
        }
        if (disjunction.hasAlternative() && disjunction.hasNext()) {
            appendable.append('|');
        }
        RENode.Disjunction next = disjunction.getNext();
        if (next != null) {
            next.accept(this);
        }
    }

    protected void visit(RENode.Alternative alternative) throws IOException, NullPointerException {
        alternative.getExpr().accept(this);
        RENode.Alternative next = alternative.getNext();
        if (next != null) {
            visit(next);
        }
    }

    protected void visit(RENode.Assertion.Begin expr) throws IOException {
        appendable.append('^');
        if (expr.getQuantifier() != null) {
            expr.getQuantifier().toString(appendable);
        }
    }

    protected void visit(RENode.Assertion.End expr) throws IOException {
        appendable.append('$');
        if (expr.getQuantifier() != null) {
            expr.getQuantifier().toString(appendable);
        }
    }

    protected void visit(RENode.Group expr) throws IOException {
        appendable.append(expr.getType().getOpen());
        this.visit(expr.getDisjunction());
        appendable.append(expr.getType().getClose());
        if (expr.getQuantifier() != null) {
            expr.getQuantifier().toString(appendable);
        }
    }

    protected void visit(RENode.Char expr) throws IOException {
        Literal.escapeTo(expr.getValue(), appendable);
        if (expr.getQuantifier() != null) {
            expr.getQuantifier().toString(appendable);
        }
    }

    protected void visit(RENode.Any expr) throws IOException {
        appendable.append('.');
        if (expr.getQuantifier() != null) {
            expr.getQuantifier().toString(appendable);
        }
    }

    protected void visit(RENode.CharacterClass expr) throws IOException {
        appendable.append("[");
        expr.getExpr().accept(this);
        appendable.append("]");
        if (expr.getQuantifier() != null) {
            expr.getQuantifier().toString(appendable);
        }
    }

    protected void visit(RENode.CharacterClassExpr.Not expr) throws IOException {
        boolean needBrace = false;
        for (RENode current = expr.getParent(); current != null; current = current.getParent()) {
            if (current instanceof RENode.CharacterClassExpr.Or) {
                needBrace = true;
                break;
            } else if (current instanceof RENode.CharacterClassExpr.And) {
                needBrace = true;
                break;
            } else if (current instanceof RENode.CharacterClassExpr.Not) {
                needBrace = true;
                break;
            }
        }
        if (needBrace) {
            appendable.append("[");
        }
        appendable.append("^");
        expr.getNegated().accept(this);
        if (needBrace) {
            appendable.append(']');
        }
    }

    protected void visit(RENode.CharacterClassExpr.Or expr) throws IOException {
        expr.getLeft().accept(this);
        expr.getRight().accept(this);
    }

    protected void visit(RENode.CharacterClassExpr.And expr) throws IOException {
        expr.getLeft().accept(this);
        appendable.append("&&");
        expr.getRight().accept(this);
    }

    protected void visit(RENode.CharacterClassExpr.Range expr) throws IOException {
        visit(expr.getFrom());
        appendable.append('-');
        visit(expr.getTo());
    }

    protected void visit(RENode.CharacterClassExpr.Char expr) throws IOException {
        Literal.escapeTo(expr.getValue(), appendable);
    }
}