Phan\Analysis\ConditionVisitor::visitCall PHP Method

    public function visitCall(Node $node) : Context
    {
        // Only look at things of the form
        // `is_string($variable)`
        if (count($node->children['args']->children) !== 1 || !$node->children['args']->children[0] instanceof Node || $node->children['args']->children[0]->kind !== \ast\AST_VAR || !$node->children['expr'] instanceof Node || empty($node->children['expr']->children['name'] ?? null) || !is_string($node->children['expr']->children['name'])) {
            return $this->context;
        }
        // Translate the function name into the UnionType it asserts
        $map = array('is_array' => 'array', 'is_bool' => 'bool', 'is_callable' => 'callable', 'is_double' => 'float', 'is_float' => 'float', 'is_int' => 'int', 'is_integer' => 'int', 'is_long' => 'int', 'is_null' => 'null', 'is_numeric' => 'string|int|float', 'is_object' => 'object', 'is_real' => 'float', 'is_resource' => 'resource', 'is_scalar' => 'int|float|bool|string|null', 'is_string' => 'string', 'empty' => 'null');
        $function_name = $node->children['expr']->children['name'];
        if (!isset($map[$function_name])) {
            return $this->context;
        }
        $type = UnionType::fromFullyQualifiedString($map[$function_name]);
        $context = $this->context;
        try {
            // Get the variable we're operating on
            $variable = (new ContextNode($this->code_base, $this->context, $node->children['args']->children[0]))->getVariable();
            if ($variable->getUnionType()->isEmpty()) {
                $variable->getUnionType()->addType(NullType::instance());
            }
            // Make a copy of the variable
            $variable = clone $variable;
            $variable->setUnionType(clone $variable->getUnionType());
            // Change the type to match the is_a relationship
            if ($type->isType(ArrayType::instance()) && $variable->getUnionType()->hasGenericArray()) {
                // If the variable is already a generic array,
                // note that it can be an arbitrary array without
                // erasing the existing generic type.
                $variable->getUnionType()->addUnionType($type);
            } else {
                // Otherwise, overwrite the type for any simple
                // primitive types.
                $variable->setUnionType($type);
            }
            // Overwrite the variable with its new type in this
            // scope without overwriting other scopes
            $context = $context->withScopeVariable($variable);
        } catch (\Exception $exception) {
            // Swallow it
        }
        return $context;
    }