text_variations.php

<?php

/**
 * 
 * @param string $txt Text to variate. All synonyms myst be placed in curly parenthesis, separated by pipe sign 
 * (ex. $txt = "I own {2|3} phones manufactured by {Apple|Samsung|HTC}.")
 * @param boolean $shuffle Shuffle variations. If false, 
 * @return string[] All possible variations of $txt
 */
function create_text_variations($txt, $shuffle = true) {
	$pattern = "/\{([^\}]+)\}/u";
	$matches = null;
	preg_match_all($pattern, $txt, $matches);
	$max_arr = array_map(function($curr){ return count(explode('|', $curr)); }, $matches[1]);
	$variations = [];
	// Find how many variations we expect
	$max = array_product($max_arr);
	$segments = count($max_arr);
	$curr_arr = array_fill(0, $segments, 0);
	$curr_segment = 0;
	while (count($variations) < $max) {
		$variations[] = preg_replace_callback($pattern, function($match) use($max_arr, $segments, &$curr_arr, &$curr_segment) {
			$possible = explode('|', $match[1]);
			$return = $possible[$curr_arr[$curr_segment]];
			$curr_segment++;
			if ($curr_segment == $segments) {
				$curr_segment = 0;
				$i = 0;
				$j = 0;
				$incremented = false;
				while (!$incremented && $i < $segments) {
					if ($curr_arr[$i]+1 < $max_arr[$i]) {
						$curr_arr[$i]++;
						$incremented = true;
						while ($j < $i) {
							$curr_arr[$j++] = 0;
						}
						break;
					} else {
						$i++;
					}
				}
			}
			return $return;
		}, $txt);
	}
	if ($shuffle) {
		shuffle($variations);
	}
	return $variations;
}