001/****************************************************************
002 * Licensed to the Apache Software Foundation (ASF) under one   *
003 * or more contributor license agreements.  See the NOTICE file *
004 * distributed with this work for additional information        *
005 * regarding copyright ownership.  The ASF licenses this file   *
006 * to you under the Apache License, Version 2.0 (the            *
007 * "License"); you may not use this file except in compliance   *
008 * with the License.  You may obtain a copy of the License at   *
009 *                                                              *
010 *   http://www.apache.org/licenses/LICENSE-2.0                 *
011 *                                                              *
012 * Unless required by applicable law or agreed to in writing,   *
013 * software distributed under the License is distributed on an  *
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
015 * KIND, either express or implied.  See the License for the    *
016 * specific language governing permissions and limitations      *
017 * under the License.                                           *
018 ****************************************************************/
019
020package org.apache.james.mime4j.stream;
021
022/**
023 * This class represents a context of a parsing operation:
024 * <ul>
025 *  <li>the current position the parsing operation is expected to start at</li>
026 *  <li>the bounds limiting the scope of the parsing operation</li>
027 * </ul>
028 * <p/>
029 * Copied from Apache HttpCore project
030 */
031public class ParserCursor {
032
033    private final int lowerBound;
034    private final int upperBound;
035    private int pos;
036
037    public ParserCursor(int lowerBound, int upperBound) {
038        super();
039        if (lowerBound < 0) {
040            throw new IndexOutOfBoundsException("Lower bound cannot be negative");
041        }
042        if (lowerBound > upperBound) {
043            throw new IndexOutOfBoundsException("Lower bound cannot be greater then upper bound");
044        }
045        this.lowerBound = lowerBound;
046        this.upperBound = upperBound;
047        this.pos = lowerBound;
048    }
049
050    public int getLowerBound() {
051        return this.lowerBound;
052    }
053
054    public int getUpperBound() {
055        return this.upperBound;
056    }
057
058    public int getPos() {
059        return this.pos;
060    }
061
062    public void updatePos(int pos) {
063        if (pos < this.lowerBound) {
064            throw new IndexOutOfBoundsException("pos: "+pos+" < lowerBound: "+this.lowerBound);
065        }
066        if (pos > this.upperBound) {
067            throw new IndexOutOfBoundsException("pos: "+pos+" > upperBound: "+this.upperBound);
068        }
069        this.pos = pos;
070    }
071
072    public boolean atEnd() {
073        return this.pos >= this.upperBound;
074    }
075
076    public String toString() {
077        StringBuilder buffer = new StringBuilder();
078        buffer.append('[');
079        buffer.append(Integer.toString(this.lowerBound));
080        buffer.append('>');
081        buffer.append(Integer.toString(this.pos));
082        buffer.append('>');
083        buffer.append(Integer.toString(this.upperBound));
084        buffer.append(']');
085        return buffer.toString();
086    }
087
088}