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/*
 ***** BEGIN LICENSE BLOCK *****
 * Version: EPL 1.0/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Eclipse Public
 * License Version 1.0 (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.eclipse.org/legal/epl-v10.html
 *
 * Software distributed under the License is distributed on an "AS
 * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * rights and limitations under the License.
 *
 * Copyright (C) 2004-2006 Thomas E Enebo 
 * Copyright (C) 2004 Jan Arne Petersen 
 * Copyright (C) 2004 Stefan Matthias Aust 
 * Copyright (C) 2005 Zach Dennis 
 * Copyright (C) 2007-2010 JRuby Community
 * Copyright (C) 2007 Charles O Nutter 
 * Copyright (C) 2007 Nick Sieger 
 * Copyright (C) 2007 Ola Bini 
 * Copyright (C) 2007 William N Dortch 
 * 
 * Alternatively, the contents of this file may be used under the terms of
 * either of the GNU General Public License Version 2 or later (the "GPL"),
 * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the EPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the EPL, the GPL or the LGPL.
 ***** END LICENSE BLOCK *****/
package org.jruby.truffle.parser.lexer;

import com.oracle.truffle.api.source.Source;
import org.jcodings.Encoding;
import org.jruby.truffle.parser.ParserByteList;

import java.nio.charset.StandardCharsets;

public class LexerSource {

    private final Source source;
    private final int lineStartOffset;

    private ParserByteList sourceBytes;

    private int byteOffset;

    public LexerSource(Source source, int lineStartOffset, Encoding encoding) {
        this.source = source;
        this.lineStartOffset = lineStartOffset;
        this.sourceBytes = new ParserByteList(source.getCode().getBytes(StandardCharsets.UTF_8), encoding);
    }

    public Source getSource() {
        return source;
    }

    public Encoding getEncoding() {
        return sourceBytes.getEncoding();
    }

    public void setEncoding(Encoding encoding) {
        sourceBytes = sourceBytes.withEncoding(encoding);
    }

    public int getOffset() {
        return byteOffset;
    }

    public int getLineStartOffset() {
        return lineStartOffset;
    }

    public ParserByteList gets() {
        if (byteOffset >= sourceBytes.getLength()) {
            return null;
        }

        int lineEnd = nextNewLine() + 1;

        if (lineEnd == 0) {
            lineEnd = sourceBytes.getLength();
        }

        final int start = byteOffset;
        final int length = lineEnd - byteOffset;

        byteOffset = lineEnd;

        return sourceBytes.makeShared(start, length);
    }

    private int nextNewLine() {
        int n = byteOffset;

        while (n < sourceBytes.getLength()) {
            if (sourceBytes.charAt(n) == '\n') {
                return n;
            }

            n++;
        }

        return -1;
    }

}