/**
* Evaluate a Script.
*
* @param string $expression to parse
* @param Context $context the context in which the expression is evaluated
* @param int $environment the environment in which the expression is evaluated
* @return Literals\Literal parsed value
*/
public function evaluate($expression, $context, $environment = self::DEFAULT_ENV)
{
self::$context = $context;
$operands = [];
$tokens = $this->parse($expression, $context, $environment);
while (count($tokens)) {
$token = array_shift($tokens);
if ($token instanceof ScriptFunction) {
$perform = $token->perform();
array_push($operands, $perform);
} elseif ($token instanceof Literals\Literal) {
if ($token instanceof Literals\SassString) {
$token = new Literals\SassString($this->interpolate($token->toString(), self::$context));
}
array_push($operands, $token);
} else {
$args = [];
for ($i = 0, $c = $token->operandCount; $i < $c; $i++) {
$args[] = array_pop($operands);
}
array_push($operands, $token->perform($args));
}
}
return self::makeSingular($operands);
}
/**
* Lex an expression into Script tokens.
*
* @param string $string expression to lex
* @param Context $context the context in which the expression is lexed
* @return array tokens
*/
public function lex($string, $context)
{
// if it's already lexed, just return it as-is
if (is_object($string)) {
return [$string];
}
if (is_array($string)) {
return $string;
}
$tokens = [];
// whilst the string is not empty, split it into it's tokens.
while ($string !== FALSE) {
if (($match = $this->isWhitespace($string)) !== FALSE) {
$tokens[] = NULL;
} elseif (($match = ScriptFunction::isa($string)) !== FALSE) {
preg_match(ScriptFunction::MATCH_FUNC, $match, $matches);
$args = [];
foreach (ScriptFunction::extractArgs($matches[ScriptFunction::ARGS], FALSE, $context) as $key => $expression) {
$args[$key] = $this->parser->evaluate($expression, $context);
}
$tokens[] = new ScriptFunction($matches[ScriptFunction::NAME], $args);
} elseif (($match = Literals\Boolean::isa($string)) !== FALSE) {
$tokens[] = new Literals\Boolean($match);
} elseif (($match = Literals\Colour::isa($string)) !== FALSE) {
$tokens[] = new Literals\Colour($match);
} elseif (($match = Literals\Number::isa($string)) !== FALSE) {
$tokens[] = new Literals\Number($match);
} elseif (($match = Literals\SassString::isa($string)) !== FALSE) {
$stringed = new Literals\SassString($match);
$tokens[] = !strlen($stringed->quote) && Literals\SassList::isa($string) !== FALSE && !preg_match("/^\\-\\w+\\-\\w+\$/", $stringed->value) ? new Literals\SassList($string) : $stringed;
} elseif ($string == '()') {
$match = $string;
$tokens[] = new Literals\SassList($match);
} elseif (($match = Operation::isa($string)) !== FALSE) {
$tokens[] = new Operation($match);
} elseif (($match = Variable::isa($string)) !== FALSE) {
$tokens[] = new Variable($match);
} else {
$_string = $string;
$match = '';
while (strlen($_string) && !$this->isWhitespace($_string)) {
foreach (Operation::$inStrOperators as $operator) {
if (substr($_string, 0, strlen($operator)) == $operator) {
break 2;
}
}
$match .= $_string[0];
$_string = substr($_string, 1);
}
$tokens[] = new Literals\SassString($match);
}
$string = substr($string, strlen($match));
}
return $tokens;
}