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    
020    package 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     */
031    public 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    }