/* This file is part of the Java 1.5 grammar for SableCC.
 *
 * Copyright 2006 Etienne M. Gagnon <egagnon@j-meg.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.sablecc.grammars.java_1_5.unicodepreprocessor.lexer.*;
import org.sablecc.grammars.java_1_5.unicodepreprocessor.node.*;
import org.sablecc.grammars.java_1_5.unicodepreprocessor.analysis.*;
import java.io.*;

public class UnicodePreprocessor extends Reader
{
    private UnicodeLexer lexer;
    private ProcessToken processor = new ProcessToken();
    
    public UnicodePreprocessor(PushbackReader in)
    {
        lexer = new UnicodeLexer(in);
    }
    
    public int read() throws IOException
    {
        if(available == 0)
	    {
		try
		    {
			lexer.next().apply(processor);
		    }
		catch(LexerException e)
		    {
			throw new RuntimeException(e.toString());
		    }
	    }
	
        if(available == 0)
	    {
		return -1;
	    }
	
        char c = buffer[0];
        buffer[0] = buffer[1];
        available--;
	
        return c;
    }
    
    public int read(
		    char cbuf[],
		    int off,
		    int len) throws IOException
    {
        for(int i = 0; i <len; i++)
	    {
		int c = read();
		
		if(c == -1)
		    {
			if(i == 0)
			    {
				return -1;
			    }
			else
			    {
				return i;
			    }
		    }
		
		cbuf[off + i] = (char) c;
	    }
	
        return len;
    }

    int available;
    char[] buffer = new char[2];
    
    private class ProcessToken extends AnalysisAdapter
    {
        public void caseTEvenBackslash(TEvenBackslash node)
        {
            buffer[0] = '\\';
            buffer[1] = '\\';
            available = 2;
        }
	
        public void caseTUnicodeEscape(TUnicodeEscape node)
        {
            String text = node.getText();
            buffer[0] = (char) Integer.parseInt(text.substring(text.length() - 4), 16);
            available = 1;
        }
	
        public void caseTErroneousEscape(TErroneousEscape node)
        {
            throw new RuntimeException("Erroneous escape: " + node);
        }
	
        public void caseTSub(TSub node)
        {
            buffer[0] = node.getText().charAt(0);
            available = 1;
        }
	
        public void caseTRawInputCharacter(TRawInputCharacter node)
        {
            buffer[0] = node.getText().charAt(0);
            available = 1;
        }
	
        public void caseEOF(EOF node)
        {
            available = 0;
        }
    }
    
    public void close()
    {
    }
}