/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
/* $Id: MODCAParser.java 1104135 2011-05-17 11:07:06Z phancock $ */
package org.apache.fop.afp.parser;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.fop.afp.parser.UnparsedStructuredField.Introducer;
/**
* An simple MO:DCA/AFP parser.
*/
public class MODCAParser {
private static final Log LOG = LogFactory.getLog(MODCAParser.class);
private static final int INTRODUCER_LENGTH = 8;
/** The carriage control character (0x5A) used to indicate the start of a structured field. */
public static final byte CARRIAGE_CONTROL_CHAR = (byte)(0x5A & 0xFF);
private DataInputStream din;
/**
* Main constructor
* @param in the {@link InputStream} to read the AFP file from.
*/
public MODCAParser(InputStream in) {
this.din = new DataInputStream(in);
}
/**
* Reads the next structured field from the input stream.
* <p>
* No structure validation of the MO:DCA file is performed.
* @return a new unparsed structured field (or null when parsing is finished).
* @throws IOException if an I/O error occurs
*/
public UnparsedStructuredField readNextStructuredField() throws IOException {
//Find the SF delimiter
do {
//Exhausted streams and so no next SF
// - null return represents this case
// TODO should this happen?
if (din.available() == 0) {
return null;
}
} while (din.readByte() != CARRIAGE_CONTROL_CHAR);
//Read introducer as byte array to preserve any data not parsed below
byte[] introducerData = new byte[INTRODUCER_LENGTH]; //Length of introducer
din.readFully(introducerData);
Introducer introducer = new Introducer(introducerData);
int dataLength = introducer.getLength() - INTRODUCER_LENGTH;
//Handle optional extension
byte[] extData = null;
if (introducer.isExtensionPresent()) {
short extLength = 0;
extLength = (short)((din.readByte()) & 0xFF);
if (extLength > 0) {
extData = new byte[extLength - 1];
din.readFully(extData);
dataLength -= extLength;
}
}
//Read payload
byte[] data = new byte[dataLength];
din.readFully(data);
UnparsedStructuredField sf = new UnparsedStructuredField(introducer, data, extData);
if (LOG.isTraceEnabled()) {
LOG.trace(sf);
}
return sf;
}
}