Prototype.php

<?php declare(strict_types=1);
 
namespace DaveRandom\CallbackValidator;
 
use DaveRandom\CallbackValidator\Type\BaseType;
use DaveRandom\CallbackValidator\Type\BuiltInType;
use DaveRandom\CallbackValidator\Type\IntersectionType;
use DaveRandom\CallbackValidator\Type\NamedType;
use DaveRandom\CallbackValidator\Type\UnionType;
use function array_map;
use function get_class;
 
final class Prototype{
    private ReturnInfo $returnInfo;
 
    private array $parameters;
 
    private int $requiredParameterCount;
 
    private static function convertReflectionTypeArray(array $types) : array{
        return array_map(fn(\ReflectionType $innerType) => self::convertReflectionTypeInner($innerType), $types);
    }
 
    private static function convertReflectionTypeInner(\ReflectionType $type) : BaseType{
        return match (true) {
            $type instanceof \ReflectionNamedType =>
                //simple nullable types are still represented by named types despite technically being unions of Type|null
                //convert these to unions so MatchTester can handle them properly
                //mixed types are considered nullable by the reflection API
                $type->allowsNull() && $type->getName() !== BuiltInType::MIXED->value ?
                    new UnionType([new NamedType($type->getName()), new NamedType(BuiltInType::NULL)]) :
                    new NamedType($type->getName()),
            $type instanceof \ReflectionUnionType => new UnionType(self::convertReflectionTypeArray($type->getTypes())),
            $type instanceof \ReflectionIntersectionType => new IntersectionType(self::convertReflectionTypeArray($type->getTypes())),
            default => throw new \AssertionError("Unhandled reflection type " . get_class($type))
        };
    }
 
    private static function convertReflectionType(?\ReflectionType $type) : ?BaseType{
        return $type === null ? null : self::convertReflectionTypeInner($type);
    }
 
    public static function fromClosure(\Closure $callable) : Prototype{
        $reflection = new \ReflectionFunction($callable);
 
        $returnType = new ReturnInfo(self::convertReflectionType($reflection->getReturnType()), $reflection->returnsReference());
 
        $parameters = [];
 
        foreach($reflection->getParameters() as $parameterReflection){
            $parameters[] = new ParameterInfo(
                $parameterReflection->getName(),
                self::convertReflectionType($parameterReflection->getType()),
                $parameterReflection->isPassedByReference(),
                $parameterReflection->isOptional(),
                $parameterReflection->isVariadic()
            );
        }
 
        return new Prototype($returnType, ...$parameters);
    }
 
    public function __construct(ReturnInfo $returnType, ParameterInfo ...$parameters){
        $this->returnInfo = $returnType;
        $this->parameters = $parameters;
        $this->requiredParameterCount = 0;
        foreach($parameters as $parameter){
            if(!$parameter->isOptional && !$parameter->isVariadic){
                $this->requiredParameterCount++;
            }
        }
    }
 
    public function isSatisfiedBy(Prototype $callable) : bool{
        if(!$this->returnInfo->isSatisfiedBy($callable->returnInfo)){
            return false;
        }
 
        if($callable->requiredParameterCount > $this->requiredParameterCount){
            return false;
        }
 
        $last = null;
 
        foreach($callable->parameters as $position => $parameter){
            // Parameters that exist in the prototype must always be satisfied directly
            if(isset($this->parameters[$position])){
                if(!$this->parameters[$position]->isSatisfiedBy($parameter)){
                    return false;
                }
 
                $last = $this->parameters[$position];
                continue;
            }
 
            // Candidates can accept additional args that are not in the prototype as long as they are not mandatory
            if(!$parameter->isOptional && !$parameter->isVariadic){
                return false;
            }
 
            // If the last arg of the prototype is variadic, any additional args the candidate accepts must satisfy it
            if($last !== null && $last->isVariadic && !$last->isSatisfiedBy($parameter)){
                return false;
            }
        }
 
        return true;
    }
 
    public function __toString() : string{
        $string = 'function ';
 
        if($this->returnInfo->byReference){
            $string .= '& ';
        }
 
        $string .= '( ';
 
        $i = $o = 0;
        $l = count($this->parameters) - 1;
        for(; $i < $l; $i++){
            $string .= $this->parameters[$i];
 
            if($o === 0 && !($this->parameters[$i + 1]->isOptional)){
                $string .= ', ';
                continue;
            }
 
            $string .= ' [, ';
            $o++;
        }
 
        if(isset($this->parameters[$l])){
            $string .= $this->parameters[$i] . ' ';
        }
 
        if($o !== 0){
            $string .= str_repeat(']', $o) . ' ';
        }
 
        $string .= ')';
 
        if($this->returnInfo->type !== null){
            $string .= ' : ' . $this->returnInfo->type->stringify();
        }
 
        return $string;
    }
}