<?php

	/*
		@author: Andrew Horsman
		@description: Incremental permutations.
	*/

	class PermutationGenerator {

		public $characters = array('!', '"', '#', '$', '%', '&', '\'', '(', ')', '*', '+', ',', '-', '.', '/', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', ':', ';', '<', '=', '>', '?', '@', 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '[', '\\', ']', '^', '_', '`', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '{', '|', '}', '~');
		private $digitMax;
		private $digits;

		public function printSeries($separator) {
			for ($x = 0; $x < count($this->digits); ++$x) {
				echo $this->characters[$this->digits[$x]];
				if ($x < count($this->digits) - 1) echo $separator;
			}
			echo "\n";
		}

		public function returnSeries() {
			for ($x = 0; $x < count($this->digits); ++$x) {
				$ret .= $this->digits[$x];
			}
			return $ret;
		}

		public function increment() {

			$this->printSeries(" ");

			if ($this->digits[count($this->digits) - 1] != $this->digitMax) {
				++$this->digits[count($this->digits) - 1];
				return 0;
			}

			$edited = 0;
			for ($x = count($this->digits) - 1; $x >= 0; --$x) {
				if ($this->digits[$x] == $this->digitMax) {
					$this->digits[$x] = 0; continue;
				} else {
					++$this->digits[$x];
					$edited = 1;
					break;
				}
			}
			if ($edited == 0) {
				array_unshift($this->digits, 0);
			}

		}

		public function __construct($digits = array(0), $characters = 0) {
			$this->digits = $digits;
			if ($characters != 0) {
				$this->characters = $characters;
			}
			$this->digitMax = count($this->characters) - 1;
		}

	}

	$instance = new PermutationGenerator();
	for ($x = 0; $x < 100; ++$x) {
		$instance->increment();
	}

?>