<?php
namespace eMacros;
class Symbol implements Expression {
/**
* Symbol expression
* @var string
*/
public $symbol;
/**
* Symbol package
* @var NULL|string
*/
public $package;
/**
* Package prefix regex
* @var string
*/
const PACKAGE_PREFIX = '/^([a-z|A-Z|_][\w]+)::/';
/**
* Symbol validation regex
* @var string
*/
const PATTERN = '{^[^\s\d(){}\[\]"\';][^\s\'"(){}\[\];]*$}';
public static function validateSymbol($symbol) {
if (!is_string($symbol)) {
throw new \UnexpectedValueException(sprintf("Symbol: unexpected value of type '%s'.", gettype($symbol)));
}
if (!preg_match(self::PATTERN, $symbol)) {
throw new \UnexpectedValueException(sprintf("Symbol: '%s' is not a valid symbol.", $symbol));
}
return $symbol;
}
public function __construct($symbol) {
//obtain package, if any
if (preg_match(self::PACKAGE_PREFIX, $symbol, $matches)) {
$this->package = $matches[1];
$symbol = substr($symbol, strlen($this->package) + 2);
}
$this->symbol = self::validateSymbol($symbol);
}
public function evaluate(Scope $scope) {
return $scope[$this];
}
public function __toString() {
return $this->symbol;
}
}
?>
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