view src/org/tmatesoft/hg/core/HgCatCommand.java @ 158:b413b16d10a5

Integer offsets and file length explictly, rather than casts throughout code. Inflater may benefit from total length hint, but shall calculate it by its own if needed
author Artem Tikhomirov <tikhomirov.artem@gmail.com>
date Wed, 09 Mar 2011 13:16:37 +0100
parents d5268ca7715b
children 41a778e3fd31
line wrap: on
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/*
 * Copyright (c) 2011 TMate Software Ltd
 *  
 * 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; version 2 of the License.
 *
 * 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.
 *
 * For information on how to redistribute this software under
 * the terms of a license other than GNU General Public License
 * contact TMate Software at support@hg4j.com
 */
package org.tmatesoft.hg.core;

import static org.tmatesoft.hg.repo.HgInternals.wrongLocalRevision;
import static org.tmatesoft.hg.repo.HgRepository.BAD_REVISION;
import static org.tmatesoft.hg.repo.HgRepository.TIP;

import java.io.FileNotFoundException;
import java.io.IOException;

import org.tmatesoft.hg.repo.HgDataFile;
import org.tmatesoft.hg.repo.HgRepository;
import org.tmatesoft.hg.util.ByteChannel;
import org.tmatesoft.hg.util.CancelledException;
import org.tmatesoft.hg.util.Path;

/**
 * Command to obtain content of a file, 'hg cat' counterpart. 
 * 
 * @author Artem Tikhomirov
 * @author TMate Software Ltd.
 */
public class HgCatCommand {

	private final HgRepository repo;
	private Path file;
	private int localRevision = TIP;
	private Nodeid revision;

	public HgCatCommand(HgRepository hgRepo) {
		repo = hgRepo;
	}

	/**
	 * File to read, required parameter 
	 * @param fname path to a repository file, can't be <code>null</code>
	 * @return <code>this</code> for convenience
	 * @throws IllegalArgumentException if supplied fname is null or points to directory
	 */
	public HgCatCommand file(Path fname) {
		if (fname == null || fname.isDirectory()) {
			throw new IllegalArgumentException(String.valueOf(fname));
		}
		file = fname;
		return this;
	}

	/**
	 * Invocation of this method clears revision set with {@link #revision(Nodeid)} or {@link #revision(int)} earlier.
	 * XXX rev can't be WORKING_COPY (if allowed, need to implement in #execute())
	 * @param rev local revision number, non-negative, or one of predefined constants. Note, use of {@link HgRepository#BAD_REVISION}, 
	 * although possible, makes little sense (command would fail if executed).  
 	 * @return <code>this</code> for convenience
	 */
	public HgCatCommand revision(int rev) {
		if (wrongLocalRevision(rev)) {
			throw new IllegalArgumentException(String.valueOf(rev));
		}
		localRevision = rev;
		revision = null;
		return this;
	}
	
	/**
	 * Select revision to read. Invocation of this method clears revision set with {@link #revision(int)} or {@link #revision(Nodeid)} earlier.
	 * 
	 * @param nodeid - unique revision identifier, Note, use of <code>null</code> or {@link Nodeid#NULL} is senseless
	 * @return <code>this</code> for convenience
	 */
	public HgCatCommand revision(Nodeid nodeid) {
		if (nodeid != null && nodeid.isNull()) {
			nodeid = null;
		}
		revision = nodeid;
		localRevision = BAD_REVISION;
		return this;
	}

	/**
	 * Runs the command with current set of parameters and pipes data to provided sink.
	 * 
	 * @param sink output channel to write data to.
	 * @throws HgDataStreamException 
	 * @throws IllegalArgumentException when command arguments are incomplete or wrong
	 */
	public void execute(ByteChannel sink) throws HgDataStreamException, IOException, CancelledException {
		if (localRevision == BAD_REVISION && revision == null) {
			throw new IllegalArgumentException("Either local file revision number or nodeid shall be specified");
		}
		if (file == null) {
			throw new IllegalArgumentException("Name of the file is missing");
		}
		if (sink == null) {
			throw new IllegalArgumentException("Need an output channel");
		}
		HgDataFile dataFile = repo.getFileNode(file);
		if (!dataFile.exists()) {
			throw new HgDataStreamException(file.toString(), new FileNotFoundException(file.toString()));
		}
		int revToExtract;
		if (revision != null) {
			revToExtract = dataFile.getLocalRevision(revision);
		} else {
			revToExtract = localRevision;
		}
		dataFile.contentWithFilters(revToExtract, sink);
	}
}