Picocli Shell JLine3 contains components and documentation for building interactive shell command line applications with JLine 3 and picocli.
JLine and picocli complement each other very well and have little or none functional overlap.
JLine provides interactive shell functionality but has no built-in command line parsing functionality. What it does provide is a tokenizer for splitting a single command line String into an array of command line argument Strings.
Given an array of Strings, picocli can execute a command or subcommand. Combining these two libraries makes it easy to build powerful interactive shell applications.
Here is an example of what can be achieved:
JLine 3 is a well-known library for building interactive shell applications. From the JLine web site:
JLine is a Java library for handling console input. It is similar in functionality to BSD editline and GNU readline but with additional features that bring it in par with ZSH line editor.
Picocli is a Java command line parser with both an annotations API and a programmatic API, featuring usage help with ANSI colors, autocomplete and nested subcommands.
The picocli user manual is here, and the GitHub project is here.
PicocliJLineCompleter is a small component that generates completion candidates to allow users to
get command line TAB auto-completion for a picocli-based application running in a JLine 3 shell.
It does not use JLine's TailTipWidgets terminal status bar and can be used with older versions of JLine.
Completion with description.
PicocliCommands is a small component, analogous to JLine's Builtins, that takes a picocli.CommandLine
object with a picocli-based command hierarchy and creates a JLine SystemCompleter for all commands in the hierarchy to set up command TAB completion in JLine.
In addition, it makes a org.jline.builtins.Widgets.CmdDesc object available for each command,
which allows a detailed description of the command and its options to be displayed in the JLine TailTipWidgets terminal status bar.
This component requires JLine 3.14.1 or greater.
The JLine TailTipWidgets terminal status bar is still under development, and the JLine API has undergone some backwards incompatible changes.
As a result, applications that use the PicocliCommands component for completion must take care to use compatible versions.
The following versions of jline and picocli-shell-jline3 are compatible:
| JLine Version | Picocli Version |
|---|---|
| 3.13.2 - 3.14.0 | 4.1.2 - 4.2.0 |
| 3.14.1 | 4.3.0 - 4.3.2 |
| 3.15.0 - | 4.4.0 - |
See examples for the older versions.
JLine Wiki and some more Demos.
<dependency>
<groupId>info.picocli</groupId>
<artifactId>picocli-shell-jline3</artifactId>
<version>4.5.2</version>
</dependency>See examples for older versions on the wiki.
- Example for JLine 3.13.2 and Picocli 4.1.2
- Example for JLine 3.14.1 and Picocli 4.3.0 - 4.3.2
- Example for JLine 3.15 and Picocli 4.4+
package picocli.shell.jline3.example;
import org.fusesource.jansi.AnsiConsole;
import org.jline.console.SystemRegistry;
import org.jline.console.impl.Builtins;
import org.jline.console.impl.SystemRegistryImpl;
import org.jline.keymap.KeyMap;
import org.jline.reader.*;
import org.jline.reader.impl.DefaultParser;
import org.jline.reader.impl.LineReaderImpl;
import org.jline.terminal.Terminal;
import org.jline.terminal.TerminalBuilder;
import org.jline.widget.TailTipWidgets;
import picocli.CommandLine;
import picocli.CommandLine.ArgGroup;
import picocli.CommandLine.Command;
import picocli.CommandLine.Option;
import picocli.CommandLine.ParentCommand;
import picocli.shell.jline3.PicocliCommands;
import java.io.IOException;
import java.io.PrintWriter;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.concurrent.Callable;
import java.util.concurrent.TimeUnit;
/**
* Example that demonstrates how to build an interactive shell with JLine3 and picocli.
* This example requires JLine 3.16+ and picocli 4.4+.
*/
public class Example {
/**
* Top-level command that just prints help.
*/
@Command(name = "",
description = {
"Example interactive shell with completion and autosuggestions. " +
"Hit @|magenta <TAB>|@ to see available commands.",
"Hit @|magenta ALT-S|@ to toggle tailtips.",
""},
footer = {"", "Press Ctl-D to exit."},
subcommands = {
MyCommand.class, ClearScreen.class, CommandLine.HelpCommand.class})
static class CliCommands implements Runnable {
LineReaderImpl reader;
PrintWriter out;
CliCommands() {}
public void setReader(LineReader reader){
this.reader = (LineReaderImpl)reader;
out = reader.getTerminal().writer();
}
public void run() {
out.println(new CommandLine(this).getUsageMessage());
}
}
/**
* A command with some options to demonstrate completion.
*/
@Command(name = "cmd", mixinStandardHelpOptions = true, version = "1.0",
description = {"Command with some options to demonstrate TAB-completion.",
" (Note that enum values also get completed.)"},
subcommands = {Nested.class, CommandLine.HelpCommand.class})
static class MyCommand implements Runnable {
@Option(names = {"-v", "--verbose"},
description = { "Specify multiple -v options to increase verbosity.",
"For example, `-v -v -v` or `-vvv`"})
private boolean[] verbosity = {};
@ArgGroup(exclusive = false)
private MyDuration myDuration = new MyDuration();
static class MyDuration {
@Option(names = {"-d", "--duration"},
description = "The duration quantity.",
required = true)
private int amount;
@Option(names = {"-u", "--timeUnit"},
description = "The duration time unit.",
required = true)
private TimeUnit unit;
}
@ParentCommand CliCommands parent;
public void run() {
if (verbosity.length > 0) {
parent.out.printf("Hi there. You asked for %d %s.%n",
myDuration.amount, myDuration.unit);
} else {
parent.out.println("hi!");
}
}
}
@Command(name = "nested", mixinStandardHelpOptions = true, subcommands = {CommandLine.HelpCommand.class},
description = "Hosts more sub-subcommands")
static class Nested implements Runnable {
public void run() {
System.out.println("I'm a nested subcommand. I don't do much, but I have sub-subcommands!");
}
@Command(mixinStandardHelpOptions = true, subcommands = {CommandLine.HelpCommand.class},
description = "Multiplies two numbers.")
public void multiply(@Option(names = {"-l", "--left"}, required = true) int left,
@Option(names = {"-r", "--right"}, required = true) int right) {
System.out.printf("%d * %d = %d%n", left, right, left * right);
}
@Command(mixinStandardHelpOptions = true, subcommands = {CommandLine.HelpCommand.class},
description = "Adds two numbers.")
public void add(@Option(names = {"-l", "--left"}, required = true) int left,
@Option(names = {"-r", "--right"}, required = true) int right) {
System.out.printf("%d + %d = %d%n", left, right, left + right);
}
@Command(mixinStandardHelpOptions = true, subcommands = {CommandLine.HelpCommand.class},
description = "Subtracts two numbers.")
public void subtract(@Option(names = {"-l", "--left"}, required = true) int left,
@Option(names = {"-r", "--right"}, required = true) int right) {
System.out.printf("%d - %d = %d%n", left, right, left - right);
}
}
/**
* Command that clears the screen.
*/
@Command(name = "cls", aliases = "clear", mixinStandardHelpOptions = true,
description = "Clears the screen", version = "1.0")
static class ClearScreen implements Callable<Void> {
@ParentCommand CliCommands parent;
public Void call() throws IOException {
parent.reader.clearScreen();
return null;
}
}
private static Path workDir() {
return Paths.get(System.getProperty("user.dir"));
}
public static void main(String[] args) {
AnsiConsole.systemInstall();
try {
// set up JLine built-in commands
Builtins builtins = new Builtins(Example::workDir, null, null);
builtins.rename(Builtins.Command.TTOP, "top");
builtins.alias("zle", "widget");
builtins.alias("bindkey", "keymap");
// set up picocli commands
CliCommands commands = new CliCommands();
CommandLine cmd = new CommandLine(commands);
PicocliCommands picocliCommands = new PicocliCommands(Example::workDir, cmd);
Parser parser = new DefaultParser();
try (Terminal terminal = TerminalBuilder.builder().build()) {
SystemRegistry systemRegistry = new SystemRegistryImpl(parser, terminal, Example::workDir, null);
systemRegistry.setCommandRegistries(builtins, picocliCommands);
LineReader reader = LineReaderBuilder.builder()
.terminal(terminal)
.completer(systemRegistry.completer())
.parser(parser)
.variable(LineReader.LIST_MAX, 50) // max tab completion candidates
.build();
builtins.setLineReader(reader);
commands.setReader(reader);
TailTipWidgets widgets = new TailTipWidgets(reader, systemRegistry::commandDescription, 5, TailTipWidgets.TipType.COMPLETER);
widgets.enable();
KeyMap<Binding> keyMap = reader.getKeyMaps().get("main");
keyMap.bind(new Reference("tailtip-toggle"), KeyMap.alt("s"));
String prompt = "prompt> ";
String rightPrompt = null;
// start the shell and process input until the user quits with Ctrl-D
String line;
while (true) {
try {
systemRegistry.cleanUp();
line = reader.readLine(prompt, rightPrompt, (MaskingCallback) null, null);
systemRegistry.execute(line);
} catch (UserInterruptException e) {
// Ignore
} catch (EndOfFileException e) {
return;
} catch (Exception e) {
systemRegistry.trace(e);
}
}
}
} catch (Throwable t) {
t.printStackTrace();
} finally {
AnsiConsole.systemUninstall();
}
}
}