Password Iterator vs GeneratorOriginal commented password iterator implementation: https://gist.github.com/elazar/1342491

PasswordGenerator.php

<?php
function PasswordGenerator($min = 1, $max = null)
{
    $ord = range(32, 126);
    $chr = array_map('chr', $ord);
    $first = reset($chr);
    $last = end($chr);
    $length = $min;
    $password = array_fill(0, $length, $first);
    $stop = array_fill(0, $length, $last);
    $end = $length - 1;
    while ($max ? $max >= $length : true) {
        yield implode('', $password);
        if ($password == $stop) {
            $length++;
            $password = array_fill(0, $length, $first);
            $stop = array_fill(0, $length, $last);
            $end = $length - 1;
        } else {
            for ($left = $end; isset($password[$left]) && $password[$left] == $last; $left--);
            if (isset($password[$left]) && $password[$left] != $last) {
                $password[$left] = $chr[array_search($password[$left], $chr) + 1];
                for ($index = $left + 1; $index < $length; $index++) {
                    $password[$index] = $first;
                }
            }
        }
    }
}

PasswordIterator.php

<?php
class PasswordIterator implements Iterator
{
	protected $length;
	protected $min;
	protected $max;
	protected $counter;
	protected $password;
	protected $chr;
	protected $ord;
	protected $first;
	protected $last;
	protected $end;
	protected $stop;
	public function __construct($min = 1, $max = null)
	{
		$this->min = $min;
		$this->max = $max;
		$this->ord = range(32, 126);
		$this->chr = array_map('chr', $this->ord);
		$this->first = reset($this->chr);
		$this->last = end($this->chr);
		$this->rewind();
	}
	protected function increment()
	{
		$this->length++;
		$this->password = array_fill(0, $this->length, $this->first);
		$this->stop = array_fill(0, $this->length, $this->last);
		$this->end = $this->length - 1;
	}
	public function rewind()
	{
		$this->length = $this->min - 1;
		$this->counter = 1;
		$this->increment();
	}
	public function current()
	{
		return implode('', $this->password);
	}
	public function key()
	{
		return $this->counter;
	}
	public function next()
	{
		$this->counter++;
		if ($this->password == $this->stop) {
			$this->increment();
		} else {
			for ($left = $this->end; isset($this->password[$left]) && $this->password[$left] == $this->last; $left--);
			if (isset($this->password[$left]) && $this->password[$left] != $this->last) {
				$this->password[$left] = $this->chr[array_search($this->password[$left], $this->chr) + 1];
				for ($index = $left + 1; $index < $this->length; $index++) {
					$this->password[$index] = $this->first;
				}
			}
		}
	}
	public function valid()
	{
		return $this->max ? ($this->max >= $this->length) : true;
	}
}

Wonder if this could feasibly be rewritten to use a recursive generator?