/*
 * Copyright (C) 2016, Christian Halstrick <christian.halstrick@sap.com> and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0 which is available at
 * https://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */
package org.eclipse.jgit.attributes;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

An abstraction for JGit's builtin implementations for hooks and filters. Instead of spawning an external processes to start a filter/hook and to pump data from/to stdin/stdout these builtin commmands may be used. They are constructed by FilterCommandFactory. 
Since:
4.6/**
 * An abstraction for JGit's builtin implementations for hooks and filters.
 * Instead of spawning an external processes to start a filter/hook and to pump
 * data from/to stdin/stdout these builtin commmands may be used. They are
 * constructed by {@link org.eclipse.jgit.attributes.FilterCommandFactory}.
 *
 * @since 4.6
 */
public abstract class FilterCommand {
	
The InputStream this command should read from /**
	 * The {@link InputStream} this command should read from
	 */
	protected InputStream in;

	
The OutputStream this command should write to /**
	 * The {@link OutputStream} this command should write to
	 */
	protected OutputStream out;

	
Constructor for FilterCommand

FilterCommand implementors are required to manage the in and out streams
(close on success and/or exception).
Params:
in –  The InputStream this command should read from
out –  The OutputStream this command should write to/**
	 * Constructor for FilterCommand
	 * <p>
	 * FilterCommand implementors are required to manage the in and out streams
	 * (close on success and/or exception).
	 *
	 * @param in
	 *            The {@link java.io.InputStream} this command should read from
	 * @param out
	 *            The {@link java.io.OutputStream} this command should write to
	 */
	public FilterCommand(InputStream in, OutputStream out) {
		this.in = in;
		this.out = out;
	}

	
Execute the command. The command is supposed to read data from in and to write the result to out. It returns the number of bytes it read from in. It should be called in a loop until it returns -1 signaling that the InputStream is completely processed. 
 On successful completion (return -1) or on Exception, the streams in and out are closed by the implementation. 
Throws:
IOException –  when IOException occurred while reading from in or writing to out
Returns:
the number of bytes read from the InputStream or -1. -1 means that the InputStream is completely processed./**
	 * Execute the command. The command is supposed to read data from
	 * {@link #in} and to write the result to {@link #out}. It returns the
	 * number of bytes it read from {@link #in}. It should be called in a loop
	 * until it returns -1 signaling that the {@link java.io.InputStream} is
	 * completely processed.
	 * <p>
	 * On successful completion (return -1) or on Exception, the streams
	 * {@link #in} and {@link #out} are closed by the implementation.
	 *
	 * @return the number of bytes read from the {@link java.io.InputStream} or
	 *         -1. -1 means that the {@link java.io.InputStream} is completely
	 *         processed.
	 * @throws java.io.IOException
	 *             when {@link java.io.IOException} occurred while reading from
	 *             {@link #in} or writing to {@link #out}
	 */
	public abstract int run() throws IOException;
}