GenericParser.java

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/*
 * (c) copyright 2008, Technische Universitaet Graz and Technische Universitaet Wien
 *
 * This file is part of jdiagengine.
 *
 * jdiagengine 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 3 of the License, or
 * (at your option) any later version.
 *
 * jdiagengine 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 jdiagengine. If not, see <http://www.gnu.org/licenses/>.
 *
 * Authors: Joerg Weber, Franz Wotawa
 * Contact: jweber@ist.tugraz.at (preferred), or fwotawa@ist.tugraz.at
 *
 */


package theoremprover;

import java.lang.*;    // Java language classes 
import java.awt.*;     // User Interface components
import java.io.*;      // IO specific classes (File, Stream,..)
import java.awt.event.*;   // Event handling

import theoremprover.*;


public class GenericParser extends Object
{

    // Instance variables ...

    protected GenericScanner scanner;
    protected String source;
    protected GenericToken actualToken;
    protected Object result;
    protected String errorMessage;

    // Instance creation and initialization

    GenericParser()
    {
        errorMessage = null;
        scanner = defaultScanner();
        source = "";
        actualToken = null;
        result = null;
    }

    GenericParser(String str)
    {
        errorMessage = null;
        scanner = defaultScanner();
        source = str;
        actualToken = null;
        result = null;
    }

    public GenericScanner defaultScanner()
    {
        return new GenericScanner();
    }

    // Accessing

    public Object result()
    {
        return result;
    }

    public String errorMessage()
    {
        return errorMessage;
    }

    // Parsing

    public boolean parse(String str)
    // Returns true if the parser accepts the given string and
    // false otherwise
    {
        boolean noerror = true;
        errorMessage = null;
        result = defaultResult();
        source = str;
        actualToken = scanner.scanSource(str);
        try {
            parse();
        } catch (ParserErrorException e) {
            errorMessage = e.getMessage();
            noerror = false;
        }
        return noerror;
    }

    public Object defaultResult()
    {
        return null;
    }

    public boolean parseFile (String file)
    {
        FileInputStream freader;
        String str;
        try{
            freader = new FileInputStream(file);
        } catch (FileNotFoundException e) {
            return false;
        }
        try {
            byte[] chars = new byte[freader.available()];
            freader.read(chars);
            freader.close();
            str = new String(chars);
        } catch (IOException e){
            return false;
        }
        return parse(str);
    }


    // Private parsing

    public void parse () throws ParserErrorException {}

    public void nextToken () throws ParserErrorException
    {
        if (actualToken.isEOI()) {
            // Do nothing after dedecting the end of the input
        } else {
            actualToken = scanner.scanToken();
        }

        if (actualToken.isErrorToken()) {
            throw new ParserErrorException(
                             "Lexical Error at position " + 
                             Integer.toString(actualToken.position()));
        }
    }

    public void errorDetected () throws ParserErrorException
    {
        throw new ParserErrorException(
                           "Parser Error [ " +
                           actualToken.value() +
                           " ] at position " +
                           Integer.toString(actualToken.position()));
    }

    public void errorDetected (String str) throws ParserErrorException
    {
        throw new ParserErrorException(
                           "Parser Error [ " +
                           actualToken.value() +
                           " ] at position " +
                           Integer.toString(actualToken.position()) +
                           " [ " + str + " ] ");
    }

}