Supports Pascal ".text" file formats.

src/com/webcodepro/applecommander/storage/filters/PascalTextFileFilter.java

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+/*
+ * AppleCommander - An Apple ][ image utility.
+ * Copyright (C) 2004 by Robert Greene
+ * robgreene at users.sourceforge.net
+ *
+ * This program is free software; you can redistribute it and/or modify it 
+ * under the terms of the GNU General Public License as published by the 
+ * Free Software Foundation; either version 2 of the License, or (at your 
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but 
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along 
+ * with this program; if not, write to the Free Software Foundation, Inc., 
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+package com.webcodepro.applecommander.storage.filters;
+
+import java.io.ByteArrayOutputStream;
+import java.io.PrintWriter;
+
+import com.webcodepro.applecommander.storage.FileEntry;
+import com.webcodepro.applecommander.storage.FileFilter;
+
+/**
+ * Filter the given file as a Pascal ".text" file.
+ * <p>
+ * From the Apple Pascal v1.2 Operating System Reference manual:
+ * <quote>
+ * <b>Text files in Apple Pascal</b>
+ * <hr>
+ * At the beginning of each textfile is a 1024-byte (two blocks on
+ * diskette) header page, which contains information for the texteditor. 
+ * This space is reserved for use by the text editor, and is respected 
+ * by all portions of the system. When a user program opens a text file, 
+ * and REWRITEs or RESETs it with a title ending in .TEXT, the I/O 
+ * subsystem will create and skip over the initial header page. This is 
+ * done to faciliatie users editing their input and/or output data. The 
+ * file-handler wil transfer the header page only on a disk-to-disk 
+ * transfer, and will omit it on a transfer to a serial device (thus 
+ * transfers to PRINTER: abd CONSOLE: will omit the header page).
+ * <p>
+ * Following the initial header page, the text itself appears in 
+ * subsequent 1024-byte text pages (two block each, on diskette), 
+ * where a text page is defined:<br>
+ * <pre>
+ *     [DLE] [indent] [text] [cr] [dle] [indent] [text] [CR] .. [nulls]
+ * </pre>
+ * DLE's (Data Link Escapes) are followed by an indent-code, which is a 
+ * byte containing the value 32+(number to indent). The nulls at the 
+ * end of the page follow a [CR} in all cases, and are a pad to the end 
+ * of a 1024-byte page (because the compiler wants integral numbers of 
+ * lines on a page). The Data Link Escape and corresponding indentation 
+ * code are optional. In a given text file, some lines will have the 
+ * codes, and some won't.
+ * </quote>
+ * (Thanks to Hans Otten for sending in this information.)
+ *
+ * @author: Rob Greene
+ */
+public class PascalTextFileFilter implements FileFilter {
+	private static final char NUL = 0x00;
+	private static final char CR = 0x0d;
+	private static final char DLE = 0x10;
+	private static final int HEADER_SIZE = 1024;
+	private static final int INDENT_BASE_VALUE = 0x20;
+	
+	/**
+	 * Constructor for PascalTextFileFilter.
+	 */
+	public PascalTextFileFilter() {
+		super();
+	}
+
+	/**
+	 * Process the given FileEntry and return a byte array 
+	 * with filtered data; use PrintWriter to get platform 
+	 * agnostic line endings.
+	 */
+	public byte[] filter(FileEntry fileEntry) {
+		byte[] fileData = fileEntry.getFileData();
+		int offset = HEADER_SIZE;
+		ByteArrayOutputStream byteArray = new
+			ByteArrayOutputStream(fileData.length);
+		PrintWriter printWriter = new PrintWriter(byteArray, true);
+		while (offset < fileData.length) {
+			char c = (char)(fileData[offset] & 0x7f);	// Will the bitwise AND be a problem??
+			switch (c) {
+				case NUL:	break;		// ignore
+				case CR:	printWriter.println();
+							break;
+				case DLE:	if (offset+1 < fileData.length) {
+								offset++;
+								int indent = fileData[offset] - INDENT_BASE_VALUE;
+								while (indent-- > 0) {
+									printWriter.print(' ');
+								}
+							}
+							break;
+				default:	printWriter.print(c);
+							break;
+			}
+			offset++;
+		}
+		return byteArray.toByteArray();
+	}
+
+
+	/**
+	 * Give suggested file name.
+	 */
+	public String getSuggestedFileName(FileEntry fileEntry) {
+		String fileName = fileEntry.getFilename().trim();
+		if (!fileName.toLowerCase().endsWith(".txt")) {
+			fileName = fileName + ".txt";
+		}
+		return fileName;
+	}
+}