มͷ࣮ public function evaluate($node) { switch (get_class($node)) { // ... case PhpParser\Node\Stmt\Expression::class: $this->evaluate($node->expr); return; case PhpParser\Node\Expr\Assign::class: return $this->variableEnv[$node->var->name] = $this->evaluate($node->expr); case PhpParser\Node\Expr\Variable::class: return $this->variableEnv[$node->name];