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libphutil/src/grammar/PhutilContextFreeGrammar.php
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PhutilContextFreeGrammar.php
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<?php
/**
* Generate nonsense test data according to a context-free grammar definition.
*/
abstract class PhutilContextFreeGrammar {
private $limit = 65535;
abstract protected function getRules();
public function generateSeveral($count, $implode = ' ') {
$paragraph = array();
for ($ii = 0; $ii < $count; $ii++) {
$paragraph[$ii] = $this->generate();
}
return implode($implode, $paragraph);
}
public function generate() {
$count = 0;
$rules = $this->getRules();
return $this->applyRules('[start]', $count, $rules);
}
final protected function applyRules($input, &$count, array $rules) {
if (++$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);
$options = array();
if (($name_end = strpos($token_name, ','))) {
$options_parser = new PhutilSimpleOptions();
$options = $options_parser->parse($token_name);
$token_name = substr($token_name, 0, $name_end);
}
if (empty($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, $rules);
if (isset($options['indent'])) {
if (is_numeric($options['indent'])) {
$replacement = self::strPadLines($replacement, $options['indent']);
} else {
$replacement = self::strPadLines($replacement);
}
}
if (isset($options['trim'])) {
switch ($options['trim']) {
case 'left':
$replacement = ltrim($replacement);
break;
case 'right':
$replacement = rtrim($replacement);
break;
default:
case 'both':
$replacement = trim($replacement);
break;
}
}
if (isset($options['block'])) {
$replacement = "\n".$replacement."\n";
}
$input = substr_replace($input, $replacement, $offset, strlen($token));
}
return $input;
}
private static function strPadLines($text, $num_spaces = 2) {
$text_lines = phutil_split_lines($text);
foreach ($text_lines as $linenr => $line) {
$text_lines[$linenr] = str_repeat(' ', $num_spaces).$line;
}
return implode('', $text_lines);
}
}
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