Microoptimizations.

array_key_exists() is a very tiny bit faster than isset().

src/Handlers/HandlerFactory.php

@@ -44,7 +44,7 @@ public static function getFor($name, $strict = \true) {
 
 		// Using caching is of course faster than repeatedly building strings
 		// and checking classes and stuff.
-		if (isset(self::$handlersCache[$name])) {
+		if (\array_key_exists($name, self::$handlersCache)) {
 			return self::$handlersCache[$name];
 		}
 

src/Handlers/Kinds/ArgumentList.php

@@ -21,19 +21,25 @@ class ArgumentList extends SimpleHandler {
 
 	protected static function handle(array $node, Context $context) {
 
-		if (!isset($node['args'])) {
+		if (!\array_key_exists('args', $node)) {
 			return [];
 		}
 
 		$args = [];
 		$kwargs = [];
 
 		foreach ($node['args'] as $arg) {
-			if (isset($arg['argKey'])) {
+			if (\array_key_exists('argKey', $arg)) {
 				$kwargs[$arg['argKey']['text']] = HandlerFactory::runNode($arg['argVal'], $context);
 			} else {
 
 				$result = HandlerFactory::runNode($arg['argVal'], $context);
+
+				// Argument might have been a starred expression, in which case
+				// the result is an array (see StarredExpression handler) - so
+				// let's unpack it.
+				// Single-starred expression is returned as a list array.
+				// Double-starred expression is returned as a dict array.
 				if (\is_array($result)) {
 					if (\array_is_list($result)) {
 						$args = [...$args, ...$result];

src/Handlers/Kinds/Chain.php

@@ -22,7 +22,7 @@ public static function chain(
 		$value = $handler::chain($node['core'], $context, $subject);
 
 		// If there's chain, handle it, too.
-		if (isset($node['chain'])) {
+		if (\array_key_exists('chain', $node)) {
 			$handler = HandlerFactory::getFor($node['chain']['name']);
 			return $handler::chain($node['chain'], $context, $value);
 		}

src/Handlers/Kinds/Invocation.php

@@ -19,7 +19,7 @@ public static function chain(
 	) {
 
 		$arguments = \null;
-		if (isset($node['args'])) {
+		if (\array_key_exists('args', $node)) {
 			$arguments = HandlerFactory::runNode($node['args'], $context);
 		}
 

src/Handlers/Kinds/Operand.php

@@ -16,7 +16,7 @@ protected static function handle(array $node, Context $context) {
 		$value = HandlerFactory::runNode($node['core'], $context);
 
 		// If there's chain, handle it.
-		if (isset($node['chain'])) {
+		if (\array_key_exists('chain', $node)) {
 			$handler = HandlerFactory::getFor($node['chain']['name']);
 			return $handler::chain($node['chain'], $context, $value);
 		}

src/Handlers/Kinds/ReturnStatement.php

@@ -14,7 +14,7 @@ class ReturnStatement extends SimpleHandler {
 	protected static function handle(array $node, Context $context) {
 
 		$retval = new CallRetval(
-			isset($node['subject'])
+			\array_key_exists('subject', $node)
 				? HandlerFactory::runNode($node['subject'], $context)
 				: \null
 		);

src/Structures/AssignmentTargets.php

@@ -67,7 +67,7 @@ public function assign(AbstractValue $value, Context $ctx) {
 		$targetIndex = 0;
 		foreach ($iter as $value) {
 
-			if (isset($this->targets[$targetIndex])) {
+			if (\array_key_exists($targetIndex, $this->targets)) {
 				$buffer[$this->targets[$targetIndex]] = $value;
 			} else {
 				throw new RuntimeError(

src/Structures/CallArgs.php

@@ -221,7 +221,7 @@ public function extract($names, $optional = []) {
 		foreach ($names as $name) {
 			if (
 				$name[0] !== '*'
-				&& !isset($final[$name])
+				&& !\array_key_exists($name, $final)
 				&& !\in_array($name, $optional, \true)
 			) {
 				throw new TypeError("Missing required argument '$name'");

src/Structures/FnContainer.php

@@ -140,7 +140,7 @@ public static function buildFromClosure(callable $fn, array $flags = []) {
 
 		$flagToStack = \in_array(self::FLAG_TO_STACK, $flags, \true);
 		$flagCallConventionArgsObject =
-			in_array(self::FLAG_CALLCONV_CALLARGS, $flags, \true);
+			\in_array(self::FLAG_CALLCONV_CALLARGS, $flags, \true);
 
 		$callConvention = $flagCallConventionArgsObject
 			? new CallArgsCallConvention($closure)

src/Structures/MapContainer.php

@@ -93,7 +93,7 @@ public function set(AbstractValue $key, AbstractValue $value): void {
 	 * @throws UnhashableTypeException
 	 */
 	public function hasKey(AbstractValue $key): bool {
-		return isset($this->values[self::buildScalarKey($key)]);
+		return \array_key_exists(self::buildScalarKey($key), $this->values);
 	}
 
 	/**

src/Values/AbstractValue.php

@@ -55,7 +55,7 @@ public static function buildAuto($value) {
 				}
 
 				$inner = \array_map(__METHOD__, $value);
-				if (!array_is_list($value)) {
+				if (!\array_is_list($value)) {
 					return new DictValue(Func::array_to_couples($inner));
 				}
 				return new ListValue($inner);

src/Values/ModuleValue.php

@@ -61,7 +61,7 @@ public function getStringRepr(): string {
 	 * Return number of variables in the module's scope.
 	 */
 	public function getLength(): ?int {
-		return count($this->value->getVariables());
+		return \count($this->value->getVariables());
 	}
 
 	/**

tools/phpcb-benchmarks/key_exists_vs_isset.php

@@ -3,9 +3,9 @@
 require __DIR__ . "/../../vendor/autoload.php";
 $bench = new \Smuuf\Phpcb\PhpBenchmark;
 
-$arr =  ['x' => 1, 'y' => 2, 'z' => false, "key" => 1, 'a' => 'b', 'c' => 0];
-$arr2 = ['x' => 1, 'y' => 2, 'z' => false, "foo" => 1, 'a' => 'b', 'c' => 0];
-$arr3 = ['x' => 1, 'y' => 2, 'z' => false, "key" => null, 'a' => 'b', 'c' => 0];
+$arr =  [...range(50, 500), 'x' => 1, 'y' => 2, 'z' => false, "key" => 1, 'a' => 'b', 'c' => 0];
+$arr2 = [...range(50, 500), 'x' => 1, 'y' => 2, 'z' => false, "foo" => 1, 'a' => 'b', 'c' => 0];
+$arr3 = [...range(50, 500), 'x' => 1, 'y' => 2, 'z' => false, "key" => null, 'a' => 'b', 'c' => 0];
 
 $bench->addBench(function() use ($arr) {
 	$x = isset($arr['key']);