feat(query): add rank feature query

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Spamercz

doc/02-query-objects.md

@@ -519,6 +519,19 @@ new \Spameri\ElasticQuery\Query\MoreLikeThis(
 );
 ```
 
+##### RankFeature Query
+Boost documents by a `rank_feature` field (saturation/log/sigmoid/linear functions).
+- Class: `\Spameri\ElasticQuery\Query\RankFeature`
+- [Documentation](https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-rank-feature-query.html)
+- [Implementation](https://github.com/Spameri/ElasticQuery/blob/master/src/Query/RankFeature.php)
+
+```php
+new \Spameri\ElasticQuery\Query\RankFeature(
+	field: 'pagerank',
+	function: ['saturation' => ['pivot' => 8]],
+);
+```
+
 ##### Script Query
 Filter documents with a Painless boolean script.
 - Class: `\Spameri\ElasticQuery\Query\Script`

src/Query/RankFeature.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types = 1);
+
+namespace Spameri\ElasticQuery\Query;
+
+/**
+ * @see https://www.elastic.co/guide/en/elasticsearch/reference/current/query-dsl-rank-feature-query.html
+ */
+class RankFeature implements \Spameri\ElasticQuery\Query\LeafQueryInterface
+{
+
+	/**
+	 * @param array<string, mixed>|null $function Optional scoring function:
+	 *                                            ['saturation' => ['pivot' => 8]] | ['log' => ['scaling_factor' => 4]]
+	 *                                            | ['sigmoid' => ['pivot' => 7, 'exponent' => 0.6]] | ['linear' => new \stdClass()].
+	 */
+	public function __construct(
+		private string $field,
+		private array|null $function = null,
+		private float $boost = 1.0,
+	)
+	{
+	}
+
+
+	public function key(): string
+	{
+		return 'rank_feature_' . $this->field;
+	}
+
+
+	/**
+	 * @return array<string, array<string, mixed>>
+	 */
+	public function toArray(): array
+	{
+		$body = [
+			'field' => $this->field,
+			'boost' => $this->boost,
+		];
+
+		if ($this->function !== null) {
+			foreach ($this->function as $name => $config) {
+				$body[$name] = $config;
+			}
+		}
+
+		return [
+			'rank_feature' => $body,
+		];
+	}
+
+}

tests/SpameriTests/ElasticQuery/Query/RankFeature.phpt

@@ -0,0 +1,61 @@
+<?php declare(strict_types = 1);
+
+namespace SpameriTests\ElasticQuery\Query;
+
+require_once __DIR__ . '/../../bootstrap.php';
+
+
+class RankFeature extends \Tester\TestCase
+{
+
+	private const INDEX = 'spameri_test_query_rank_feature';
+
+
+	public function setUp(): void
+	{
+		$ch = \curl_init();
+		\curl_setopt($ch, \CURLOPT_URL, \ELASTICSEARCH_HOST . '/' . self::INDEX);
+		\curl_setopt($ch, \CURLOPT_RETURNTRANSFER, 1);
+		\curl_setopt($ch, \CURLOPT_CUSTOMREQUEST, 'PUT');
+		\curl_setopt($ch, \CURLOPT_HTTPHEADER, ['Content-Type: application/json']);
+
+		\curl_exec($ch);
+	}
+
+
+	public function testToArray(): void
+	{
+		$rf = new \Spameri\ElasticQuery\Query\RankFeature(
+			field: 'pagerank',
+			function: ['saturation' => ['pivot' => 8]],
+		);
+
+		$array = $rf->toArray();
+
+		\Tester\Assert::same('pagerank', $array['rank_feature']['field']);
+		\Tester\Assert::same(8, $array['rank_feature']['saturation']['pivot']);
+	}
+
+
+	public function testKey(): void
+	{
+		$rf = new \Spameri\ElasticQuery\Query\RankFeature('pagerank');
+
+		\Tester\Assert::same('rank_feature_pagerank', $rf->key());
+	}
+
+
+	public function tearDown(): void
+	{
+		$ch = \curl_init();
+		\curl_setopt($ch, \CURLOPT_URL, \ELASTICSEARCH_HOST . '/' . self::INDEX);
+		\curl_setopt($ch, \CURLOPT_RETURNTRANSFER, 1);
+		\curl_setopt($ch, \CURLOPT_CUSTOMREQUEST, 'DELETE');
+		\curl_setopt($ch, \CURLOPT_HTTPHEADER, ['Content-Type: application/json']);
+
+		\curl_exec($ch);
+	}
+
+}
+
+(new RankFeature())->run();