CallbackType.php

<?php declare(strict_types = 1);
 
namespace DaveRandom\CallbackValidator;
 
final class CallbackType
{
    private $returnType;
 
    private $parameters;
 
    private static function reflectCallable($target)
    {
        if ($target instanceof \Closure) {
            return new \ReflectionFunction($target);
        }
 
        if (\is_array($target) && isset($target[0], $target[1])) {
            return new \ReflectionMethod($target[0], $target[1]);
        }
 
        if (\is_object($target) && \method_exists($target, '__invoke')) {
            return new \ReflectionMethod($target, '__invoke');
        }
 
        if (\is_string($target)) {
            return \strpos($target, '::') !== false
                ? new \ReflectionMethod($target)
                : new \ReflectionFunction($target);
        }
 
        throw new \UnexpectedValueException("Unknown callable type");
    }
 
    public static function createFromCallable($callable, $flags = ParameterType::CONTRAVARIANT | ReturnType::COVARIANT)
    {
        try {
            $reflection = self::reflectCallable($callable);
        } catch (\ReflectionException $e) {
            throw new InvalidCallbackException('Failed to reflect the supplied callable', 0, $e);
        }
 
        $returnType = ReturnType::createFromReflectionFunctionAbstract($reflection, $flags);
 
        $parameters = [];
 
        foreach ($reflection->getParameters() as $parameterReflection) {
            $parameters[] = ParameterType::createFromReflectionParameter($parameterReflection, $flags);
        }
 
        return new CallbackType($returnType, ...$parameters);
    }
 
    public function __construct(ReturnType $returnType, ParameterType ...$parameters)
    {
        $this->returnType = $returnType;
        $this->parameters = $parameters;
    }
 
    public function isSatisfiedBy($callable)
    {
        try {
            $candidate = self::reflectCallable($callable);
        } catch (\ReflectionException $e) {
            throw new InvalidCallbackException('Failed to reflect the supplied callable', 0, $e);
        }
 
        $byRef = $candidate->returnsReference();
        $returnType = $candidate->getReturnType();
 
        if ($returnType instanceof \ReflectionNamedType) {
            $typeName = $returnType->getName();
            $nullable = $returnType->allowsNull();
        } elseif ($returnType !== null) {
            throw new \LogicException("Unsupported reflection type " . get_class($returnType));
        } else {
            $typeName = null;
            $nullable = false;
        }
 
        if (!$this->returnType->isSatisfiedBy($typeName, $nullable, $byRef)) {
            return false;
        }
 
        $last = null;
 
        foreach ($candidate->getParameters() as $position => $parameter) {
            $byRef = $parameter->isPassedByReference();
 
            if (($type = $parameter->getType()) instanceof \ReflectionNamedType) {
                $typeName = $type->getName();
                $nullable = $type->allowsNull();
            } elseif ($type !== null) {
                throw new \LogicException("Unsupported reflection type " . get_class($type));
            } else {
                $typeName = null;
                $nullable = false;
            }
 
            // Parameters that exist in the prototype must always be satisfied directly
            if (isset($this->parameters[$position])) {
                if (!$this->parameters[$position]->isSatisfiedBy($typeName, $nullable, $byRef)) {
                    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($typeName, $nullable, $byRef)) {
                return false;
            }
        }
 
        return true;
    }
 
    public function __toString()
    {
        $string = 'function ';
 
        if ($this->returnType->isByReference) {
            $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->returnType->typeName !== null) {
            $string .= ' : ' . $this->returnType;
        }
 
        return $string;
    }
}