example.php

<?php
require_once 'PHP/ListRubyLike.php';
use PHP\ListRubyLike;

echo PHP\LR(array('foo', 'bar'))
    ->push('baz', 'piyo')
    ->map(function ($v) { return strtoupper($v); })
    ->join(', ') . PHP_EOL;

echo PHP\LR(range(1, 5))
    ->grep(function ($n) { return $n % 2 == 0; })
    ->map(function ($n) { return $n * $n; })
    ->sum() . PHP_EOL;

ListRubyLike.php

<?php
namespace PHP;

/**
 * Array iterator like Ruby.
 *
 * @author Naoya Ito <i.naoya@gmail.com>
 * licence: TBD
 */
class ListRubyLike
{
    private $_list = array();

    public function __construct(array $array)
    {
        $this->_list = $array;
    }
    private function _new(array $array)
    {
        $class = __CLASS__;
        return new $class($array);
    }

    public function push()
    {
        $args = func_get_args();
        foreach ($args as $v) {
            array_push($this->_list, $v);
        }
        return $this;
    }

    public function pop()
    {
        return array_pop($this->_list);
    }

    public function unshift()
    {
        $args = func_get_args();
        foreach ($args as $v) {
            array_unshift($this->_list, $v);
        }
        return $this;
    }

    public function shift()
    {
        return array_shift($this->_list);
    }

    public function join($glue)
    {
        return implode($glue, $this->_list);
    }
    public function first()
    {
        return $this->_list[0];
    }

    public function last()
    {
        return end($this->_list);
    }

    public function slice($start, $end)
    {
        return $this->_new(array_slice($this->_list, $start, $end));
    }

    public function each($cb)
    {
        if (!is_callable($cb)) {
            throw new LogicException('assert');
        }

        foreach ($this->_list as $v) {
            $cb($v);
        }
        return $this;
    }

    public function length()
    {
        return count($this->_list);
    }

    public function map($cb)
    {
        if (!is_callable($cb)) {
            throw new LogicException('assert');
        }
        return $this->_new(array_map($cb, $this->_list));
    }
    public function grep($cb)
    {
        $grepped = $this->_new(array());
        foreach ($this->_list as $v) {
            if ($cb($v) === true) {
                $grepped->push($v);
            }
        }
        return $grepped;
    }

    public function find($cb)
    {
        foreach ($this->_list as $v) {
            if ($cb($v) === true) {
                return $v;
            }
        }
        return false;
    }

    public function eachIndex($cb)
    {
        if (!is_callable($cb)) {
            throw new LogicException('assert');
        }

        foreach($this->_list as $i => $v) {
            $cb($i, $v);
        }

        return $this;
    }
    public function reduce($cb)
    {
        return array_reduce($this->_list, $cb);
    }

    public function sum()
    {
        return $this->reduce(function ($a, $b) { return $a + $b; });
    }

    public function dump()
    {
        var_dump($this);
    }

    public function to_a()
    {
        return $this->_list;
    }
}

function LR(array $array)
{
    return new ListRubyLike($array);
}

test.php

<?php
require_once 'lib/lime.php';
require_once 'PHP/ListRubyLike.php';

use PHP\ListRubyLike;

$t = new lime_test();

$list = PHP\LR(array(2, 4, 6, 8, 10));

$t->ok($list instanceof PHP\ListRubyLike);
$t->ok($list->length() === 5);
$t->ok($list->first() === 2);
$t->ok($list->last() === 10);
$t->ok($list->sum() === 30);

$t->ok($list->pop() === 10);
$t->is_deeply($list->to_a(), array(2, 4, 6, 8));

$t->ok($list->shift() === 2);
$t->is_deeply($list->to_a(), array(4, 6, 8));

$t->ok(get_class($list->push(5)) ===  'PHP\\ListRubyLike');
$t->ok($list->last() === 5);
$t->is_deeply( $list->to_a(), array(4, 6, 8, 5) );

$t->ok(get_class($list->unshift(10)) === 'PHP\\ListRubyLike');
$t->ok($list->first() === 10);
$t->is_deeply( $list->to_a(), array(10, 4, 6, 8, 5) );

$t->ok($list->join(',') === '10,4,6,8,5');
$t->is_deeply( $list->slice(2, 2)->to_a(), array(6,8));

/* TODO
   - each()
   - each_index()
   - map()
   - grep()
   - find()
   - reduce()
 */