From de059122d16d8f348242ec4df74a5adc1a86de31 Mon Sep 17 00:00:00 2001
From: Priyadi Iman Nurcahyo <1102197+priyadi@users.noreply.github.com>
Date: Sat, 17 Feb 2024 17:13:01 +0700
Subject: [PATCH] feat: LazyList, not yet used. (#11)

---
 src/ListInterface.php              |  24 ++++++
 src/Transformer/Model/LazyList.php | 115 +++++++++++++++++++++++++++++
 2 files changed, 139 insertions(+)
 create mode 100644 src/ListInterface.php
 create mode 100644 src/Transformer/Model/LazyList.php

diff --git a/src/ListInterface.php b/src/ListInterface.php
new file mode 100644
index 00000000..7086f9a7
--- /dev/null
+++ b/src/ListInterface.php
@@ -0,0 +1,24 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper;
+
+/**
+ * @template TKey of int
+ * @template TValue
+ * @extends \IteratorAggregate<TKey,TValue>
+ * @extends \ArrayAccess<TKey,TValue>
+ */
+interface ListInterface extends \ArrayAccess, \IteratorAggregate, \Countable
+{
+}
diff --git a/src/Transformer/Model/LazyList.php b/src/Transformer/Model/LazyList.php
new file mode 100644
index 00000000..19b6b98d
--- /dev/null
+++ b/src/Transformer/Model/LazyList.php
@@ -0,0 +1,115 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of rekalogika/mapper package.
+ *
+ * (c) Priyadi Iman Nurcahyo <https://rekalogika.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE file
+ * that was distributed with this source code.
+ */
+
+namespace Rekalogika\Mapper\Transformer\Model;
+
+use Rekalogika\Mapper\Context\Context;
+use Rekalogika\Mapper\ListInterface;
+use Rekalogika\Mapper\MainTransformer\MainTransformerInterface;
+use Rekalogika\Mapper\Transformer\ArrayLikeMetadata\ArrayLikeMetadata;
+use Rekalogika\Mapper\Transformer\MainTransformerAwareTrait;
+use Rekalogika\Mapper\Transformer\Trait\ArrayLikeTransformerTrait;
+
+/**
+ * Discards source key, and use incremental integer key in the target.
+ *
+ * @template TValue
+ * @implements ListInterface<int,TValue>
+ * @internal
+ */
+final class LazyList implements ListInterface
+{
+    use MainTransformerAwareTrait;
+    use ArrayLikeTransformerTrait;
+
+    /**
+     * @var array<int,TValue>
+     */
+    private array $cachedData = [];
+    private bool $isCached = false;
+
+    /**
+     * @param (\Traversable<mixed,mixed>&\ArrayAccess<mixed,mixed>&\Countable)|array<int|string,mixed> $source
+     */
+    public function __construct(
+        private (\Traversable&\ArrayAccess&\Countable)|array $source,
+        MainTransformerInterface $mainTransformer,
+        private ArrayLikeMetadata $metadata,
+        private Context $context,
+    ) {
+        $this->mainTransformer = $mainTransformer;
+    }
+
+    public function offsetExists(mixed $offset): bool
+    {
+        return isset($this->cachedData[$offset]) || isset($this->source[$offset]);
+    }
+
+    public function offsetGet(mixed $offset): mixed
+    {
+        if (!$this->isCached) {
+            foreach($this->getIterator() as $i);
+        }
+
+        return $this->cachedData[$offset];
+    }
+
+    public function offsetSet(mixed $offset, mixed $value): void
+    {
+        throw new \BadMethodCallException('LazyArray is immutable.');
+    }
+
+    public function offsetUnset(mixed $offset): void
+    {
+        throw new \BadMethodCallException('LazyArray is immutable.');
+    }
+
+    public function getIterator(): \Traversable
+    {
+        if ($this->isCached) {
+            yield from $this->cachedData;
+
+            return;
+        }
+
+        $i = 0;
+
+        /**
+         * @var mixed $sourceMemberValue
+         */
+        foreach ($this->source as $sourceMemberKey => $sourceMemberValue) {
+            /**
+             * @var TValue $value
+             */
+            [, $value] = $this->transformMember(
+                sourceMemberKey: $sourceMemberKey,
+                sourceMemberValue: $sourceMemberValue,
+                metadata: $this->metadata,
+                context: $this->context,
+            );
+
+            $this->cachedData[$i] = $value;
+
+            yield $value;
+
+            $i++;
+        }
+
+        $this->isCached = true;
+    }
+
+    public function count(): int
+    {
+        return count($this->source);
+    }
+}