feature: implement inverse token modifier

closes #475

Author: g105b

src/HTMLAttributeBinder.php

@@ -390,8 +390,8 @@ private function handleModifier(
 		string $modifier,
 		mixed $bindValue
 	):void {
-		$modifierChar = $modifier[0];
-		$modifierValue = substr($modifier, 1);
+		$modifierChar = $this->getModifierType($modifier);
+		$modifierValue = $this->getModifierBody($modifier);
 		$condition = null;
 		if(false !== $spacePos = strpos($modifierValue, " ")) {
 			$modifierValue = substr($modifierValue, $spacePos + 1);
@@ -409,6 +409,9 @@ private function handleModifier(
 		case ":":
 			$tokenList = $this->getTokenList($element, $attribute);
 			$tokenNames = $this->resolveTokenNames($modifier, $bindValue);
+			if($this->isInverseModifier($modifier)) {
+				$bindValue = !$bindValue;
+			}
 			if($bindValue) {
 				$tokenList->add(...$tokenNames);
 			}
@@ -418,7 +421,7 @@ private function handleModifier(
 			break;
 
 		case "?":
-			if($modifierValue[0] === "!") {
+			if($this->isInverseModifier($modifier)) {
 				$bindValue = !$bindValue;
 			}
 
@@ -463,8 +466,7 @@ private function extractBindKey(string $bindExpression):string {
 	}
 
 	private function extractModifierExpression(string $modifier):string {
-		$modifierValue = substr($modifier, 1);
-		$modifierValue = ltrim($modifierValue, "!");
+		$modifierValue = $this->getModifierBody($modifier);
 		return strtok($modifierValue, " ") ?: "";
 	}
 
@@ -485,8 +487,7 @@ private function resolveTokenNames(string $modifier, mixed $bindValue):array {
 
 	/** @return array<int, string> */
 	private function extractModifierTokens(string $modifier):array {
-		$modifierValue = substr($modifier, 1);
-		$modifierValue = ltrim($modifierValue, "!");
+		$modifierValue = $this->getModifierBody($modifier);
 		$spacePos = strpos($modifierValue, " ");
 		if($spacePos === false) {
 			return [];
@@ -495,6 +496,30 @@ private function extractModifierTokens(string $modifier):array {
 		return $this->prepareTokenListValues(substr($modifierValue, $spacePos + 1));
 	}
 
+	private function getModifierType(string $modifier):string {
+		foreach(str_split($modifier) as $char) {
+			if($char === ":" || $char === "?") {
+				return $char;
+			}
+		}
+
+		return $modifier[0];
+	}
+
+	private function isInverseModifier(string $modifier):bool {
+		return str_contains($modifier, "!");
+	}
+
+	private function getModifierBody(string $modifier):string {
+		$modifierType = $this->getModifierType($modifier);
+		$modifierValue = ltrim($modifier, "!");
+		if(str_starts_with($modifierValue, $modifierType)) {
+			return ltrim(substr($modifierValue, 1), "!");
+		}
+
+		return ltrim(substr($modifier, 1), "!");
+	}
+
 	private function extractCondition(string $bindExpression):?string {
 		$parts = explode("=", $bindExpression, 2);
 		return $parts[1] ?? null;

test/phpunit/HTMLAttributeBinderTest.php

@@ -158,6 +158,30 @@ public function testBind_modifierColon_removesMultipleClassNamesAtOnce():void {
 		self::assertFalse($div->classList->contains("featured"));
 	}
 
+	public function testBind_modifierColon_inverseLogic_afterTokenModifier():void {
+		$document = new HTMLDocument(HTMLPageContent::HTML_INVERSE_MODIFIER_BINDING);
+		$sut = new HTMLAttributeBinder();
+		$div = $document->getElementById("div1");
+
+		$sut->bind("show", false, $div);
+		self::assertTrue($div->classList->contains("hidden"));
+
+		$sut->bind("show", true, $div);
+		self::assertFalse($div->classList->contains("hidden"));
+	}
+
+	public function testBind_modifierColon_inverseLogic_beforeTokenModifier():void {
+		$document = new HTMLDocument(HTMLPageContent::HTML_INVERSE_MODIFIER_BINDING);
+		$sut = new HTMLAttributeBinder();
+		$div = $document->getElementById("div2");
+
+		$sut->bind("show", false, $div);
+		self::assertTrue($div->classList->contains("hidden"));
+
+		$sut->bind("show", true, $div);
+		self::assertFalse($div->classList->contains("hidden"));
+	}
+
 	public function testBind_modifierColon_multipleExpressionsCanBeBundled():void {
 		$document = new HTMLDocument(HTMLPageContent::HTML_MULTI_CLASS_BINDING);
 		$sut = new HTMLAttributeBinder();
@@ -208,6 +232,30 @@ public function testBind_modifierQuestion():void {
 		self::assertFalse($btn2->disabled);
 	}
 
+	public function testBind_modifierQuestion_inverseLogic_afterQuestionModifier():void {
+		$document = new HTMLDocument(HTMLPageContent::HTML_INVERSE_MODIFIER_BINDING);
+		$sut = new HTMLAttributeBinder();
+		$button = $document->getElementById("btn1");
+
+		$sut->bind("isEnabled", false, $button);
+		self::assertTrue($button->disabled);
+
+		$sut->bind("isEnabled", true, $button);
+		self::assertFalse($button->disabled);
+	}
+
+	public function testBind_modifierQuestion_inverseLogic_beforeQuestionModifier():void {
+		$document = new HTMLDocument(HTMLPageContent::HTML_INVERSE_MODIFIER_BINDING);
+		$sut = new HTMLAttributeBinder();
+		$button = $document->getElementById("btn2");
+
+		$sut->bind("isEnabled", false, $button);
+		self::assertTrue($button->disabled);
+
+		$sut->bind("isEnabled", true, $button);
+		self::assertFalse($button->disabled);
+	}
+
 	public function testBind_modifierQuestion_withNullValue():void {
 		$document = new HTMLDocument(HTMLPageContent::HTML_DIFFERENT_BIND_PROPERTIES);
 		$sut = new HTMLAttributeBinder();

test/phpunit/TestHelper/HTMLPageContent.php

@@ -197,6 +197,17 @@ class HTMLPageContent {
 <div id="div4" class="panel" data-bind:class=":isSelected selected; :isAdmin admin"></div>
 
 <button id="btn3" data-bind:disabled="?isBusy; ?isLocked"></button>
+HTML;
+
+	const HTML_INVERSE_MODIFIER_BINDING = <<<HTML
+<!doctype html>
+<div id="div1" class="panel" data-bind:class=":!show hidden" data-rebind></div>
+
+<div id="div2" class="panel" data-bind:class="!:show hidden" data-rebind></div>
+
+<button id="btn1" data-bind:disabled="?!isEnabled" data-rebind></button>
+
+<button id="btn2" data-bind:disabled="!?isEnabled" data-rebind></button>
 HTML;
 
 	const HTML_SIMPLE_BOOLEAN = <<<HTML