src/Handlers/Kinds/FunctionDefinition.php

Summary

Maintainability
A
3 hrs
Test Coverage
B
88%
<?php

declare(strict_types=1);

namespace Smuuf\Primi\Handlers\Kinds;

use \Smuuf\Primi\Scope;
use \Smuuf\Primi\Context;
use \Smuuf\Primi\Ex\InternalPostProcessSyntaxError;
use \Smuuf\Primi\Values\FuncValue;
use \Smuuf\Primi\Helpers\Func;
use \Smuuf\Primi\Handlers\SimpleHandler;
use \Smuuf\Primi\Structures\FnContainer;

class FunctionDefinition extends SimpleHandler {

    protected static function handle(array $node, Context $context) {

        $module = $context->getCurrentModule();
        $name = \sprintf("%s.%s()", $module->getName(), $node['fnName']);

        $currentScope = $context->getCurrentScope();

        // If a function is defined as a method inside a class (directly
        // first-level function definition in the class definition), we do not
        // want the function to have direct access to its class's scope.
        // (All access to class' attributes should be done by accessing class
        // self-reference inside the function).
        // So, in that case, instead of current scope we'll pass the parent
        // scope of the current scope as the definition scope.
        $parentScope = $currentScope->getType() === Scope::TYPE_CLASS
            ? $currentScope->getParent()
            : $currentScope;

        $fnc = FnContainer::build(
            $node['body'],
            $name,
            $module,
            $node['params'],
            $parentScope,
        );

        $currentScope->setVariable($node['fnName'], new FuncValue($fnc));

    }

    public static function reduce(array &$node): void {

        // Prepare function name.
        $node['fnName'] = $node['function']['text'];
        unset($node['function']);

        if (isset($node['params'])) {
            $node['params'] = self::prepareParameters($node['params']);
        } else {
            $node['params'] = [];
        }

    }

    /**
     * @param TypeDef_AstNode $paramsNode
     * @return array{names: array<string>, defaults: array<string, TypeDef_AstNode>}
     */
    public static function prepareParameters(array $paramsNode): array {

        // Prepare dict array for passing specifics about parameters expected
        // by the function.
        // Parameters will be prepared as a dict array with names of parameters
        // being the keys - with false as their values.
        // This makes handling the "invoke" logic used later quite easier.
        $params = [
            'names' => [],
            'defaults' => [],
        ];

        // Make sure this is always list, even with one item.
        $paramsNodes = Func::ensure_indexed($paramsNode);

        // For checking duplicate param names (without stars).
        $paramNames = [];

        $foundStarred = \false;
        $foundDoubleStarred = \false;

        foreach ($paramsNodes as $node) {

            /** @var string */
            $paramName = $node['param']['text'];

            // Detect duplicate param names - they are forbidden.
            // For this we need to use parameter names stripped of any stars,
            // because using "f(c, *c)" should still be a "duplicate parameter"
            // error.
            //
            // This happens if defining function parameters like:
            // > function f(a, b, b) { ... }

            if (\in_array($paramName, $paramNames, \true)) {
                throw new InternalPostProcessSyntaxError(
                    "Duplicate parameter name '$paramName'"
                );
            }

            // We track stripped param names as array keys so we can just
            // use isset().
            $paramNames[] = $paramName;

            // Detect wrongly positioned parameters.
            if ($foundDoubleStarred) {

                if ($node['stars'] !== StarredExpression::STARS_TWO) {
                    throw new InternalPostProcessSyntaxError(
                        "Variadic keyword parameters must be placed after all others"
                    );
                }

                throw new InternalPostProcessSyntaxError(
                    "Variadic keyword parameters must be present only once"
                );

            }

            if ($foundStarred) {
                if ($node['stars'] === StarredExpression::STARS_ONE) {
                    throw new InternalPostProcessSyntaxError(
                        "Variadic positional parameters must be present only once"
                    );
                }
            }

            $foundStarred |= $node['stars'] === StarredExpression::STARS_ONE;
            $foundDoubleStarred |= $node['stars'] === StarredExpression::STARS_TWO;

            // FnContainer expects list of arguments WITH stars - so it can
            // know which parameters actually are variadic.
            $withStars = \str_repeat('*', $node['stars']) . $paramName;
            $params['names'][] = $withStars;

            // If this parameter has a specified default value (internally
            // an AST node), place its AST node in the storage for defaults -
            // for later use when invoking the function.
            if (!empty($node['default'])) {
                $params['defaults'][$paramName] = $node['default'];
            } elseif ($params['defaults'] && !$foundStarred && !$foundDoubleStarred) {
                // Current parameter has no default value and is not
                // variadic (starred), but we already encountered some parameter
                // with default value.
                // This will not stand! Throw a syntax error.
                throw new InternalPostProcessSyntaxError(
                    "Non-default non-variadic parameter placed after default parameter"
                );
            }

        }

        return $params;

    }

}