Implement ~ Subsequent-sibling

fix #230

Author: Alkarex

composer.json

@@ -27,6 +27,15 @@
 		}
 	},
 
+	"scripts": {
+		"phpunit": "vendor/bin/phpunit --configuration test/phpunit/phpunit.xml",
+		"phpstan": "vendor/bin/phpstan analyse --level 6 src",
+		"test": [
+			"@phpunit",
+			"@phpstan"
+		]
+	},
+
 	"authors": [
 		{
 			"name": "Greg Bowler",

src/Translator.php

@@ -12,6 +12,7 @@ class Translator {
 		. '|(#(?P<id>[\w-]*))'
 		. '|(\.(?P<class>[\w-]*))'
 		. '|(?P<sibling>\s*\+\s*)'
+		. '|(?P<subsequentsibling>\s*~\s*)'
 		. "|(\[(?P<attribute>[\w-]*)((?P<attribute_equals>[=~$|^*]+)(?P<attribute_value>(.+\[\]'?)|[^\]]+))*\])+"
 		. '|(?P<descendant>\s+)'
 		. '/';
@@ -24,8 +25,8 @@ class Translator {
 	const EQUALS_STARTS_WITH = "^=";
 
 	public function __construct(
-			protected string $cssSelector, 
-			protected string $prefix = ".//", 
+			protected string $cssSelector,
+			protected string $prefix = ".//",
 			protected bool $htmlMode = true
 		) {
 	}
@@ -198,7 +199,7 @@ protected function convertSingleSelector(string $css):string {
 							"[last()]"
 						);
 					}
-					break;					
+					break;
 
 				}
 				break;
@@ -235,6 +236,14 @@ protected function convertSingleSelector(string $css):string {
 				$hasElement = false;
 				break;
 
+			case "subsequentsibling":
+				array_push(
+					$xpath,
+					"/following-sibling::"
+				);
+				$hasElement = false;
+				break;
+
 			case "attribute":
 				if(!$hasElement) {
 					array_push($xpath, "*");

test/phpunit/TranslatorTest.php

@@ -210,6 +210,21 @@ public function testSibling() {
 		);
 	}
 
+	public function testSubsequentSibling() {
+		$document = new DOMDocument("1.0", "UTF-8");
+		$document->loadHTML(Helper::HTML_COMPLEX);
+		$xpath = new DOMXPath($document);
+
+		$translator = new Translator("header ~ div");
+		$elements = $xpath->query($translator);
+
+		self::assertEquals(2, $elements->length);
+		self::assertEquals(".//header/following-sibling::div", (string)$translator);
+
+		$detailsOnly = new Translator("header ~ div.details");
+		self::assertEquals(1, $xpath->query($detailsOnly)->length);
+	}
+
 	public function testDescendant() {
 		$document = new DOMDocument("1.0", "UTF-8");
 		$document->loadHTML(Helper::HTML_COMPLEX);
@@ -296,7 +311,7 @@ public function testCaseSensitivityHtmlMode() {
 			0,
 			$xpath->query($attributeValueCaseSensitive)->length
 		);
-		
+
 		$tagNameCaseInsensitive = new Translator(
 			"dIv"
 		);