PhutilContextFreeGrammar.php
2c4192c0b5a9stable

PhutilContextFreeGrammar.php
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			<?php

			/**
			* Generate nonsense test data according to a context-free grammar definition.
			*/
			abstract class PhutilContextFreeGrammar {

			private $limit = 65535;

			abstract protected function getRules();

			public function generate() {
			$count = 0;
			return $this->applyRules('[start]', $count);
			}

			public function applyRules($input, &$count) {
			$rules = $this->getRules();

			if (++$count > $this->limit) {
			throw new Exception("Token replacement count exceeded limit!");
			}

			$matches = null;
			preg_match_all('/(\\[[^\\]]+\\])/', $input, $matches, PREG_OFFSET_CAPTURE);

			foreach (array_reverse($matches[1]) as $token_spec) {
			list($token, $offset) = $token_spec;
			$token_name = substr($token, 1, -1);

			if (empty($rules[$token_name])) {
			throw new Exception("Invalid token '{$token_name}' in grammar.");
			}

			$key = array_rand($rules[$token_name]);
			$replacement = $this->applyRules($rules[$token_name][$key], $count);

			$input = substr_replace($input, $replacement, $offset, strlen($token));
			}

			return $input;
			}

			}