Syntax.java example

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jnode-master
/*
 * $Id$
 *
 * Copyright (C) 2003-2015 JNode.org
 *
 * This library 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 library 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 library; If not, write to the Free Software Foundation, Inc., 
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */
 
package org.jnode.shell.syntax;

import java.util.Collections;
import java.util.Hashtable;
import java.util.Set;

import org.jnode.nanoxml.XMLElement;

/**
 * This is the base class for the syntax elements that are used to specify concrete 
 * command-line syntaxes for JNode commands.  The key method that a child class must
 * implement is the <code>prepare</code> method that produces the MuSyntax tree that
 * the MuParser uses when parsing or completing a command line.
 * 
 * @author crawley@jnode.org
 */
public abstract class Syntax {
    
    private static final Syntax[] NO_CHILDREN = new Syntax[0];
    
    protected final String label;
    private Syntax parent;
    private String description;


    public Syntax(String label, String description) {
        this.label = label;
        this.description = description;
    }

    public final String getLabel() {
        return label;
    }

    public final boolean isLabelled() {
        return label != null;
    }

    public abstract String format(ArgumentBundle bundle);

    /**
     * @return the set of labels for this syntactic element's children, if any.
     */
    public Set<String> childLabels() {
        return Collections.emptySet();
    }

    public Syntax getParent() {
        return parent;
    }

    public final Syntax getRoot() {
        Syntax p = parent;
        while (p.getParent() != null) {
            p = p.getParent();
        }
        return p;
    }

    public void setParent(Syntax parent) {
        this.parent = parent;
    }

    /**
     * Prepare the MuSyntax for this Syntax.  In some cases, a 'prepare' method may
     * add extra synthetic arguments to the bundle.
     * 
     * @param bundle the bundle containing the command's arguments.
     * @return the prepared MuSyntax
     */
    public abstract MuSyntax prepare(ArgumentBundle bundle);

    /**
     * Determine if a formatted syntax would need to be wrapped in "()"s when embedded
     * in a larger format
     * 
     * @param formatted a formatted syntax
     * @return <code>true</code> if surrounding "()"s are required.
     */
    protected final boolean needsBracketting(String formatted) {
        if (formatted.startsWith("(") && formatted.endsWith(")")) {
            return false;
        } else if (formatted.startsWith("[") && formatted.endsWith("]")) {
            return false;
        } else {
            return formatted.contains(" ");
        }
    }

    public String getDescription() {
        return description;
    }

    public abstract XMLElement toXML();

    protected XMLElement basicElement(String name) {
        XMLElement element = new XMLElement(new Hashtable<String, Object>(), false, false);
        element.setName(name);
        if (label != null) {
            element.setAttribute("label", label);
        }
        if (description != null) {
            element.setAttribute("description", description);
        }
        return element;
    }

    public Syntax[] getChildren() {
        return NO_CHILDREN;
    }
}