clue/arguments

The simple way to split your command line string into an array of command arguments in PHP.

v2.0.0 2016-12-18 14:37 UTC

README

The simple way to split your command line string into an array of command arguments in PHP.

You want to build an interactive command line interface (CLI) tool in PHP which reads line based user input from STDIN and you now want to break this command line down to its individual command arguments? Then this library is for you!

This is similar to what your bash (or your terminal of choice) does for you when you execute ./example.php "hello world" which then spawns your script and passes it a single argument. If you only need this during startup, then using your $argv may be sufficient. But many other tools may need similar parsing during their runtime.

Table of contents

Quickstart example

The following example code demonstrates how this library can be used to build a very simple interactive command line interface (CLI) tool that accepts a command line from user input (via STDIN) and then executes some very simple demo commands:

while (true) {
    $line = fgets(STDIN, 1024);

    $args = Clue\Arguments\split($line);
    $command = array_shift($args);

    if ($command === 'exit') {
        break;
    } elseif ($command === 'sleep') {
        sleep($args[0]);
    } elseif ($command === 'echo') {
        echo join(' ', $args) . PHP_EOL;
    } else {
        echo 'Invalid command' . PHP_EOL;
    }
}

See also the examples.

Usage

This lightweight library consists only of a single simple function. Everything resides under the Clue\Arguments namespace.

The below examples assume you use an import statement similar to this:

use Clue\Arguments;

Arguments\split(…);

Alternatively, you can also refer to them with their fully-qualified name:

\Clue\Arguments\split(…);

split()

The split(string $line) : array function can be used to split the given command line string into any array of individual command argument strings.

For the following example, let's assume we want to handle a simple addUser command like this:

// example command syntax:
// addUser <username> <realname> <homepage> <comment>

$line = 'adduser example Demo example.com Hi!';

$args = Arguments\split($line);

assert(count($args) === 5);
assert($args[0] === 'adduser');
assert($args[1] === 'example');
assert($args[2] === 'Demo');
assert($args[3] === 'example.com');
assert($args[4] === 'Hi!');

While this simple example may look like a job for a simple $args = explode(' ', $line) call, the split() function is actually way more sophisticated. It also supports parsing the following:

  • Single quoted strings ('hello world') which preserve any whitespace characters and only accept escape sequences \\ and \', e.g. 'let\'s go'.
  • Double quoted strings ("hello world") which preserve any whitespace characters and support common escape sequences such as \t\r\n etc., unicode escape sequences such as \u0020, hex escape sequences such as \x20 and octal escape sequences such as \040, e.g. "hi there\nworld!".
  • Unquoted strings are terminated at the next (unescaped) whitespace character and support common escape sequences just like double quoted strings, e.g. hi\ there\nworld!.
  • Ignores excessive whitespace around arguments, such as trailing whitespace or multiple spaces between arguments.
  • Makes very few assumptions about your input encoding otherwise, so that input is allowed to contain raw binary data as well as full UTF-8 (Unicode) support. Unicode characters may either be given as normal UTF-8 strings such as hällö or can be given as unicode escape sequences in double quoted and unquoted strings, e.g. h\u00e4ll\u00f6.

For example, this means that the following also parses as expected:

$line = 'adduser clue \'Christian Lück\' https://lueck.tv/ "Hällo\tWörld\n"';

$args = Arguments\split($line);

assert(count($args) === 5);
assert($args[0] === 'adduser');
assert($args[1] === 'clue');
assert($args[2] === 'Christian Lück');
assert($args[3] === 'https://lueck.tv');
assert($args[4] === "Hällo\tWörld\n");

Validating any of the arguments (checking lengths or value ranges etc.) is left up to higher levels, i.e. the consumer of this library. This also allows you to explicitly pass empty arguments like this:

$line = 'sendmail "" clue';

$args = Arguments\split($line);

assert(count($args) === 3);
assert($args[0] === 'sendmail');
assert($args[1] === '');
assert($args[2] === 'clue');

Parsing an empty input line or one with only whitespace will return an empty array:

$line = "\r\n";

$args = Arguments\split($line);

assert(count($args) === 0);

Parsing an input line that has unbalanced quotes (i.e. a quoted argument started without passing ending quotes), this will throw an UnclosedQuotesException. This can be useful to ask the user to correct their input:

$line = 'sendmail "hello world';

try {
    Arguments\split($line);
    // throws RuntimeException
} catch (Arguments\UnclosedQuotesException $e) {
    echo 'Please check your input.';
}

See also the following chapter if you want to (try to) correct the user input line automatically.

UnclosedQuotesException

The UnclosedQuotesException will be raised by the split() function when the input line has unbalanced quotes (i.e. a quoted argument started without passing ending quotes).

This class extends PHP's InvalidArgumentException.

The getQuotes(): string method can be used to get the quotes this argument started with:

$quotes = $e->getQuotes();

For example, this can be used to (try to) correct the user input line like this:

$line = 'sendmail "hello world';

try {
    $args = Arguments\split($line);
    // throws RuntimeException
} catch (Arguments\UnclosedQuotesException $e) {
    // retry parsing with closing quotes appended
    $args = Arguments\split($line . $e->getQuotes());
}

Note: The input line may end with a backslash in which case the appended closing quotes will actually be marked as escaped. Either handle these yourself or wrap this block in another try-catch.

The getPosition(): int method can be used to get the character position of the quotes within the input string. In the previous example, this will be at $line[9]:

$pos = $e->getPosition();

assert($pos === 9);
assert($line[$pos] === $e->getQuotes());

Install

The recommended way to install this library is through Composer. New to Composer?

This will install the latest supported version:

$ composer require clue/arguments:^2.0

See also the CHANGELOG for details about version upgrades.

This project aims to run on any platform and thus does not require any PHP extensions and supports running on legacy PHP 5.3 through current PHP 7+ and HHVM. It's highly recommended to use PHP 7+ for this project.

Tests

To run the test suite, you first need to clone this repo and then install all dependencies through Composer:

$ composer install

To run the test suite, go to the project root and run:

$ php vendor/bin/phpunit

License

MIT

More

  • If you want to register/route available commands and their arguments, you may want to look into using clue/commander.

  • If you want to build an interactive CLI tool, you may want to look into using clue/stdio-react in order to react to commands from STDIN.