parsergenerator.java

Grammatica是一个C#和Java的语法分析程序生成器(编译器的编译器)。它可以用LL(k)语法创建可读的和带有注释的源代码。它也支持创建一个运行时语法分析器

/*
 * ParserGenerator.java
 *
 * This work is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published
 * by the Free Software Foundation; either version 2 of the License,
 * or (at your option) any later version.
 *
 * This work 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, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 *
 * As a special exception, the copyright holders of this library give
 * you permission to link this library with independent modules to
 * produce an executable, regardless of the license terms of these
 * independent modules, and to copy and distribute the resulting
 * executable under terms of your choice, provided that you also meet,
 * for each linked independent module, the terms and conditions of the
 * license of that module. An independent module is a module which is
 * not derived from or based on this library. If you modify this
 * library, you may extend this exception to your version of the
 * library, but you are not obligated to do so. If you do not wish to
 * do so, delete this exception statement from your version.
 *
 * Copyright (c) 2003 Per Cederberg. All rights reserved.
 */

package net.percederberg.grammatica.output;

import java.io.File;
import java.io.IOException;

import net.percederberg.grammatica.Grammar;

/**
 * The grammar parser generator base class.
 *
 * @author   Per Cederberg, <per at percederberg dot net>
 * @version  1.0
 */
public abstract class ParserGenerator {

    /**
     * The default file comment string.
     */
    protected static final String FILE_COMMENT =
        "THIS FILE HAS BEEN GENERATED AUTOMATICALLY. DO NOT EDIT!";

    /**
     * The grammar to generate a parser for.
     */
    private Grammar grammar;

    /**
     * The base directory where to write the files.
     */
    private File baseDir = null;

    /**
     * The file comment.
     */
    private String fileComment = null;

    /**
     * Creates a new parser generator.
     * 
     * @param grammar        the grammar to use
     */
    protected ParserGenerator(Grammar grammar) {
        this.grammar = grammar;
        initialize();
    }

    /**
     * Initializes various instance variables.
     */
    private void initialize() {
        StringBuffer  buffer;
        String        str;
        int           pos;

        // Create file comment
        buffer = new StringBuffer();
        buffer.append(FILE_COMMENT);
        str = grammar.getDeclaration(Grammar.LICENSE_DECLARATION);
        if (str != null) {
            buffer.append("\n\n");
            pos = str.indexOf('\n');
            while (pos >= 0) {
                buffer.append(str.substring(0, pos).trim());
                buffer.append('\n');
                str = str.substring(pos + 1);
                pos = str.indexOf('\n');
            }
            buffer.append(str.trim());
        }
        str = grammar.getDeclaration(Grammar.COPYRIGHT_DECLARATION);
        if (str != null) {
            buffer.append("\n\n");
            buffer.append(str);
        }
        fileComment = buffer.toString();
    }

    /**
     * Returns the grammar that this parser generator works on.
     * 
     * @return the parser generator grammar
     */
    public Grammar getGrammar() {
        return grammar;
    }

    /**
     * Returns the base directory where files will be created.
     * 
     * @return the base directory
     */
    public File getBaseDir() {
        return baseDir;
    }

    /**
     * Sets the base directory where files will be created.
     * 
     * @param dir            the base directory
     */
    public void setBaseDir(File dir) {
        this.baseDir = dir;
    }
    
    /**
     * Returns the file comment.
     * 
     * @return the file comment
     */
    public String getFileComment() {
        return fileComment;
    }
    
    /**
     * Writes the source code files.
     * 
     * @throws IOException if the files couldn't be written correctly
     */
    public abstract void write() throws IOException;
}