Simple PHP REPL

repl.php

#!/usr/bin/env php
<?php
if (php_sapi_name() !== 'cli') {
    exit(1);
}

function input() {
  return fgets(STDIN);
}

function output($val) {
    fputs(STDOUT, $val);
}

function colour($text = '', $colour = null) {
    $styles = array(
        'green'  => "\033[0;32m%s\033[0m",
        'red'    => "\033[31;31m%s\033[0m",
        'yellow' => "\033[33;33m%s\033[0m",
        'blue'   => "\033[33;34m%s\033[0m",
    );

    return sprintf(isset($styles[$colour]) ? $styles[$colour] : "%s", $text);
}

function cmd($cmd, $input) {
    $input = trim($input);
    return substr($input, 0, strlen($cmd)) === $cmd;
}

function snip($cmd, $input) {
    return substr($input, strlen($cmd));
}

function asi($input) {
    if (trim($input) === '') {
        return $input;
    }

    return rtrim($input, "\n;") . ';';
}

output('PHP Version ' . colour(PHP_VERSION, 'green') . PHP_EOL);
output('quit:    Exit the REPL' . PHP_EOL);
output('dump:    Perform a vardump()' . PHP_EOL);
output('printr:  Perform a print_r()' . PHP_EOL);
output('exec:    Execute an external program' . PHP_EOL);
output('>>>:     Start a heredoc of PHP code' . PHP_EOL);
output('<<<:     End a heredoc of PHP code' . PHP_EOL);
output('!!!:     Discard a heredoc of PHP code' . PHP_EOL);
output(PHP_EOL);

$buffer = '';
$buffering = false;

while (true) {
    output(colour('> ', $buffering ? 'blue' : 'yellow'));

    $input = input();
    if (cmd('quit', $input)) {
        exit;
    }

    if (cmd('exec', $input)) {
        exec(snip('exec', $input), $result);
        $result = trim(implode("\n", $result));
        if (! empty($result)) {
            output($result . PHP_EOL);
        }
        continue;
    }

    if (cmd('dump', $input)) {
        $input = 'var_dump(' . snip('dump', $input) . ');';
    } elseif (cmd('printr', $input)) {
        $input = 'print_r(' . snip('printr', $input) . ');';
    }

    if (cmd('>>>', $input)) {
        $buffering = true;
        $input = snip('>>>', $input);
    } elseif (cmd('<<<', $input)) {
        if (! $buffering) {
            continue;
        }

        $buffering = false;
        $input = snip('<<<', $input);
    } elseif (cmd('!!!', $input)) {
        $buffering = false;
        $buffer = '';
        continue;
    }

    if ($buffering) {
        $buffer .= $input;
        continue;
    }

    if (! empty($buffer)) {
        $input  = $buffer;
        $buffer = '';
    } else {
        $input = asi($input) . PHP_EOL; 
    }

    eval($input);
    output(PHP_EOL);
}

usage.sh

php repl.php
> $i = 0
> $i++
> echo $i
1
> quit

php repl.php
> >>>
> class Foo extends StdClass 
> {
>   // Your code goes here.
>   // Spans mulitple lines.
> }
> <<<
> $f = new Foo
> $f->first = 'Joe'
> $f->last = 'Bloggs'
> dump $f
> quite