yay-map.php

<?php declare(strict_types=1);

namespace YAY;

use Countable;
use IteratorAggregate;
use Traversable;
use Webmozart\Assert\Assert;

/**
 * @template T of object
 * @implements IteratorAggregate<string, T>
 */
final class Map implements IteratorAggregate, Countable
{
    /**
     * @var array<string, T>
     */
    private array $objects;

    /**
     * @param array<T> $objects
     * @param class-string<T> $type
     * @param \Closure(T $object): non-empty-string $indexer
     */
    private function __construct(
        private readonly string $type,
        private readonly \Closure $indexer,
        array $objects,
    ) {
        $this->objects = [];
        foreach ($objects as $object) {
            $this->add($object);
        }
    }

    /**
     * @template TCreate of object
     * @param array<TCreate> $objects
     * @param class-string<TCreate> $type
     * @return Map<TCreate>
     */
    public static function byProperty(string $propertyName, string $type, array $objects): self
    {
        $indexer = function (object $object) use ($type, $propertyName): string {
            $value = $object->{$propertyName};

            if (!is_string($value) && !is_int($value)) {
                throw new \LogicException('Cannot use property ' . $propertyName . ' of ' . $object::class . ' as index, because I must be able to cast it to string.');
            }

            $stringedValue = (string) $value;

            if ($stringedValue === "") {
                throw new \RuntimeException('The indexer did not index an object correctly: ' . $type . '. The string was empty.');
            }

            return $stringedValue;
        };

        return new self($type, $indexer, $objects);
    }

    /**
     * @template TCreate of object
     * @param array<TCreate> $objects
     * @param class-string<TCreate> $type
     * @return Map<TCreate>
     */
    public static function byMethod(string $methodName, string $type, array $objects): self
    {
        $indexer = function (object $object) use ($type, $methodName): string {
            $value = $object->{$methodName}();

            if (!is_string($value) && !is_int($value)) {
                throw new \LogicException('Cannot use return value from method ' . $methodName . ' of ' . $object::class . ' as index, because I must be able to cast it to string.');
            }

            $stringedValue = (string) $value;

            if ($stringedValue === "") {
                throw new \RuntimeException('The indexer did not index an object correctly: ' . $type . '. The string was empty.');
            }

            return $stringedValue;
        };

        return new self($type, $indexer, $objects);
    }

    public function has(string $key): bool
    {
        return array_key_exists($key, $this->objects);
    }

    /**
     * @param T $object
     */
    public function add(object $object): void
    {
        Assert::isInstanceOf($object, $this->type); // @phpstan-ignore staticMethod.alreadyNarrowedType
        $index = ($this->indexer)($object);
        $this->objects[$index] = $object;
    }

    /**
     * @return T
     */
    public function get(string $key)
    {
        if (!$this->has($key)) {
            throw new \OutOfBoundsException('Object not found by indexed ' . $key);
        }

        return $this->objects[$key];
    }

    public function getIterator(): Traversable
    {
        return new \ArrayIterator($this->objects);
    }

    public function count(): int
    {
        return count($this->objects);
    }

    public function remove(string $key): void
    {
        unset($this->objects[$key]);
    }
}

Makes code so much more readable than array_key_exists, isset and using plan arrays:

    /**
     * @param list<N26CsvRow> $csvs
     * @return list<TransactionAggregate>
     */
    public function syncCsvTransactions(array $csvs, TenantIdentifier $tenantIdentifier, ZonedDateTime $at): array
    {
        $index = $this->repository->getIndex();

        $transactions = [];
        foreach ($csvs as $csv) {
            $hash = $csv->hash();
            
            if ($index->has($hash)) {
                $this->logger->notice($csv . ', is already imported.');
                continue;
            }

            $transactions[] = $transaction = TransactionAggregate::createFromN26CsvRow(
                TransactionIdentifier::create(),
                $tenantIdentifier,
                $csv,
                $at,
            );

            $this->repository->save($transaction);
        }

        return $transactions;
    }