Combinator

src/Iterators/CachedIterator.php

@@ -0,0 +1,95 @@
+<?php
+
+/**
+ * This file is part of the Nette Framework (https://nette.org)
+ * Copyright (c) 2004 David Grudl (https://davidgrudl.com)
+ */
+
+declare(strict_types=1);
+
+namespace Nette\Iterators;
+
+
+class CachedIterator implements \Iterator, \Countable, \SeekableIterator
+{
+	private \Iterator $iterator;
+	private int $offset = -1;
+	private array $keys = [];
+	private array $values = [];
+
+
+	public function __construct(iterable $iterator)
+	{
+		$this->iterator = is_array($iterator) ? new \ArrayIterator($iterator) : $iterator;
+	}
+
+
+	public function rewind(): void
+	{
+		$this->offset = 0;
+		$this->fetchUntil(0);
+	}
+
+
+	public function current(): mixed
+	{
+		return $this->values[$this->offset];
+	}
+
+
+	public function key(): mixed
+	{
+		return $this->keys[$this->offset];
+	}
+
+
+	public function next(): void
+	{
+		if ($this->offset < count($this->values)) {
+			$this->offset++;
+			$this->fetchUntil($this->offset);
+		}
+	}
+
+
+	public function valid(): bool
+	{
+		return $this->offset < count($this->values);
+	}
+
+
+	public function count(): int
+	{
+		$this->fetchUntil(PHP_INT_MAX);
+		return count($this->values);
+	}
+
+
+	public function seek(int $offset): void
+	{
+		if ($offset >= count($this->values)) {
+			$this->fetchUntil($offset);
+		}
+		if ($offset < 0 || $offset >= count($this->values)) {
+			throw new \OutOfBoundsException("Invalid seek position $offset");
+		}
+		$this->offset = $offset;
+	}
+
+
+	private function fetchUntil(int $limit): void
+	{
+		while ($limit >= count($this->values)) {
+			if ($this->values) {
+				$this->iterator->next();
+			} else {
+				$this->iterator->rewind();
+			}
+			if (!$this->iterator->valid()) {
+				break;
+			}
+			$this->keys[] = $this->iterator->key();
+			$this->values[] = $this->iterator->current();
+		}
+	}
+}

src/Iterators/Combinator.php

@@ -0,0 +1,68 @@
+<?php
+
+/**
+ * This file is part of the Nette Framework (https://nette.org)
+ * Copyright (c) 2004 David Grudl (https://davidgrudl.com)
+ */
+
+declare(strict_types=1);
+
+namespace Nette\Iterators;
+
+
+class Combinator implements \Iterator, \Countable, \SeekableIterator
+{
+	private int $offset = 0;
+
+
+	public function __construct(
+		private array $keys,
+		private array $values,
+	) {
+	}
+
+
+	public function rewind(): void
+	{
+		$this->offset = 0;
+	}
+
+
+	public function current(): mixed
+	{
+		return $this->values[$this->offset];
+	}
+
+
+	public function key(): mixed
+	{
+		return $this->keys[$this->offset];
+	}
+
+
+	public function next(): void
+	{
+		$this->offset++;
+	}
+
+
+	public function valid(): bool
+	{
+		return $this->offset < count($this->values);
+	}
+
+
+	public function count(): int
+	{
+		return count($this->values);
+	}
+
+
+	public function seek(int $offset): void
+	{
+		if ($offset < 0 || $offset >= count($this->values)) {
+			throw new \OutOfBoundsException("Invalid seek position $offset");
+		}
+		$this->offset = $offset;
+	}
+}

tests/Iterators/CachedIterator.phpt

@@ -0,0 +1,60 @@
+<?php
+
+/**
+ * Test: Nette\Iterators\CachedIterator
+ */
+
+declare(strict_types=1);
+
+use Nette\Iterators\CachedIterator;
+use Tester\Assert;
+
+require __DIR__ . '/../bootstrap.php';
+
+
+$data = ['a' => 'apple', 'b' => 'banana', 'c' => 'cherry'];
+
+// iteration
+$iterator = new CachedIterator($data);
+$expectedKeys = array_keys($data);
+$expectedValues = array_values($data);
+$index = 0;
+foreach ($iterator as $key => $value) {
+	Assert::same($expectedKeys[$index], $key);
+	Assert::same($expectedValues[$index], $value);
+	$index++;
+}
+Assert::same(count($data), $index);
+
+// re-iteration
+$index = 0;
+foreach ($iterator as $key => $value) {
+	Assert::same($expectedKeys[$index], $key);
+	Assert::same($expectedValues[$index], $value);
+	$index++;
+}
+Assert::same(count($data), $index);
+
+// count + re-iteration
+$iterator = new CachedIterator($data);
+Assert::same(count($data), count($iterator));
+$index = 0;
+foreach ($iterator as $key => $value) {
+	Assert::same($expectedKeys[$index], $key);
+	Assert::same($expectedValues[$index], $value);
+	$index++;
+}
+Assert::same(count($data), $index);
+
+// seek
+$iterator = new CachedIterator($data);
+$iterator->seek(1);
+Assert::same('banana', $iterator->current());
+Assert::exception(
+	fn() => $iterator->seek(-1),
+	OutOfBoundsException::class,
+);
+Assert::exception(
+	fn() => $iterator->seek(3),
+	OutOfBoundsException::class,
+);

tests/Iterators/Combinator.phpt

@@ -0,0 +1,51 @@
+<?php
+
+/**
+ * Test: Nette\Iterators\Combinator
+ */
+
+declare(strict_types=1);
+
+use Nette\Iterators\Combinator;
+use Tester\Assert;
+
+require __DIR__ . '/../bootstrap.php';
+
+
+$keys = [true, false];
+$values = ['value1', 'value2'];
+$combinator = new Combinator($keys, $values);
+Assert::same(count($combinator), count($values));
+
+// iteration
+$index = 0;
+foreach ($combinator as $key => $value) {
+	Assert::equal($keys[$index], $key);
+	Assert::equal($values[$index], $value);
+	$index++;
+}
+
+// count
+Assert::same(count($values), $index);
+
+// re-iteration
+$index = 0;
+foreach ($combinator as $key => $value) {
+	Assert::equal($keys[$index], $key);
+	Assert::equal($values[$index], $value);
+	$index++;
+}
+
+Assert::same(count($values), $index);
+
+// seek
+$combinator->seek(1);
+Assert::same('value2', $combinator->current());
+Assert::exception(
+	fn() => $combinator->seek(-1),
+	OutOfBoundsException::class,
+);
+Assert::exception(
+	fn() => $combinator->seek(2),
+	OutOfBoundsException::class,
+);