/**
* Creates a closure from a lambda expression.
*
* @param string $expr The expression.
* @param bool $throwException Throw exception or return (false) instead.
*
* @return \Closure|bool The closure or (false) on error.
*
* @throws ArgumentException $expr is no valid expression.
*/
public static function toLambda($expr, bool $throwException = true)
{
$throwOrReturn = function () use($throwException) {
if ($throwException) {
throw new System\ArgumentException('expr', 'No lambda expression!', null, 0);
}
return false;
};
if (!ClrString::canBeString($expr)) {
return $throwOrReturn();
}
$expr = trim(ClrString::valueToString($expr));
// check for lambda
if (1 === preg_match("/^(\\s*)([\\(]?)([^\\)]*)([\\)]?)(\\s*)(=>)/m", $expr, $lambdaMatches)) {
if (empty($lambdaMatches[2]) && !empty($lambdaMatches[4]) || !empty($lambdaMatches[2]) && empty($lambdaMatches[4])) {
if ($throwException) {
throw new System\ArgumentException('expr', 'Syntax error in lambda expression!', null, 1);
}
return false;
}
$lambdaBody = trim(substr($expr, strlen($lambdaMatches[0])), '{}' . " \t\n\r\v");
// remove surrounding {}
if ('' !== $lambdaBody) {
if (';' !== \substr($lambdaBody, -1)) {
// auto add return statement
$lambdaBody = 'return ' . $lambdaBody . ';';
}
}
return self::execGlobal('return function(' . $lambdaMatches[3] . ') { ' . $lambdaBody . ' };');
}
return $throwOrReturn();
}
/**
* Returns a value as stream.
*
* @param mixed $val The input value.
*
* @return IStream|null $val as stream or (null) if $val is also (null).
*
* @throws ArgumentException $val is invalid.
*/
public static function asStream($val)
{
if ($val instanceof IStream) {
return $val;
}
if (null === $val) {
return null;
}
if (\is_resource($val)) {
return new self($val, false);
}
if (ClrString::canBeString($val)) {
return new MemoryStream($val);
}
throw new ArgumentException('val');
}
