[JGIT PATCH 01/22] Start of an implementation of a git like command line tool.

[Florian Koeberle <florianskarten@web.de>]

Only the "help" command is currenly supported, but it is extendable.

Signed-off-by: Florian Koeberle <florianskarten@web.de>
---
 .../src/org/spearce/jgit/pgm/Command.java          |   40 +++++++
 .../src/org/spearce/jgit/pgm/MainProgram.java      |  114 ++++++++++++++++++++
 2 files changed, 154 insertions(+), 0 deletions(-)
 create mode 100644 org.spearce.jgit/src/org/spearce/jgit/pgm/Command.java
 create mode 100644 org.spearce.jgit/src/org/spearce/jgit/pgm/MainProgram.java

diff --git a/org.spearce.jgit/src/org/spearce/jgit/pgm/Command.java b/org.spearce.jgit/src/org/spearce/jgit/pgm/Command.java
new file mode 100644
index 0000000..cf66b20
--- /dev/null
+++ b/org.spearce.jgit/src/org/spearce/jgit/pgm/Command.java
@@ -0,0 +1,40 @@
+/*
+ *  Copyright (C) 2008 Florian Köberle
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public
+ *  License, version 2, as published by the Free Software Foundation.
+ *
+ *  This library 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 library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
+ */
+package org.spearce.jgit.pgm;
+
+import java.io.IOException;
+
+/**
+ * A command have tasks like the "git-add", "git-help" or "git-init" console commands.
+ * Instances of ${link Command} must be immutable.
+ * @author Florian Köberle
+ *
+ */
+public interface Command {
+	/**
+	 * Executes the specified Command.
+	 * @param args the arguments which you would pass to the console equivalent of the command.
+	 * @throws IOException for some undefined reasons.
+	 */
+	public void execute(String... args) throws IOException;
+
+	/**
+	 * 
+	 * @return a short description about what the command does. Short means in this context 5 - 10 words.
+	 */
+	public String getShortDescription();
+}
\ No newline at end of file
diff --git a/org.spearce.jgit/src/org/spearce/jgit/pgm/MainProgram.java b/org.spearce.jgit/src/org/spearce/jgit/pgm/MainProgram.java
new file mode 100644
index 0000000..72b0156
--- /dev/null
+++ b/org.spearce.jgit/src/org/spearce/jgit/pgm/MainProgram.java
@@ -0,0 +1,114 @@
+/*
+ *  Copyright (C) 2008 Florian Köberle
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU General Public
+ *  License, version 2, as published by the Free Software Foundation.
+ *
+ *  This library 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 library; if not, write to the Free Software
+ *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301
+ */
+package org.spearce.jgit.pgm;
+
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.SortedMap;
+import java.util.TreeMap;
+
+/**
+ * A program which works similar like the command git, except that very view
+ * arguments are supported jet.
+ * 
+ * @author Florian Köberle
+ * 
+ */
+public class MainProgram {
+	private final static Map<String, Command> commandNameToObjectMap;
+
+	static {
+		final Map<String, Command> commands = new HashMap<String, Command>();
+		commands.put("help", HelpCommand.INSTANCE);
+		commandNameToObjectMap = Collections.unmodifiableMap(commands);
+	}
+
+	/**
+	 * Executes a command with some arguments. There are commands for creating
+	 * git repositories, tracking files, etc.
+	 * 
+	 * @param args
+	 *            The first argument specifies the command which should be
+	 *            executed. The other arguments are passed to the command.
+	 * @throws IOException
+	 *             for some reasons.
+	 */
+	public static void main(String[] args) throws IOException {
+		try {
+			if (args.length == 0) {
+				throw new WrongCallException("Require one argument!");
+			}
+			final Command command = commandNameToObjectMap.get(args[0]);
+			if (command == null) {
+				throw new WrongCallException("Require one argument!");
+			}
+			final String[] commandArguments = Arrays.copyOfRange(args, 1,
+					args.length);
+			command.execute(commandArguments);
+
+		} catch (WrongCallException e) {
+			System.err.println(e.getMessage());
+			System.err.println();
+			HelpCommand.INSTANCE.execute();
+			System.exit(1);
+		}
+	}
+
+	private static class WrongCallException extends Exception {
+		private static final long serialVersionUID = 3643362832429311084L;
+
+		WrongCallException(String message) {
+			super(message);
+		}
+	}
+
+	private static class HelpCommand implements Command {
+		/**
+		 * Use this instance instead of creating a new ${link HelpCommand}. You
+		 * don't need to create an instance of this class as it is immutable and
+		 * not configurable.
+		 */
+		public static HelpCommand INSTANCE = new HelpCommand();
+
+		public void execute(String... args) throws IOException {
+			System.out
+					.println("Call this program with the following arguments:");
+			System.out
+					.println("commandName commandArgument0 commandArgument1 ...");
+			System.out.println();
+			System.out
+					.println("Currently the following commands are supported:");
+			final SortedMap<String, Command> sortedCommandMap = new TreeMap<String, Command>(
+					MainProgram.commandNameToObjectMap);
+			for (Map.Entry<String, Command> commandEntry : sortedCommandMap
+					.entrySet()) {
+				final String commandName = commandEntry.getKey();
+				final String commandDescription = commandEntry.getValue()
+						.getShortDescription();
+				System.out.printf("%#10s - %s%n", commandName,
+						commandDescription);
+			}
+		}
+
+		public String getShortDescription() {
+			return "Displays some text about how to use this program.";
+		}
+	}
+}
-- 
1.5.2.5