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<?php |
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namespace Vikpe; |
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class HtmlHeadingNormalizer |
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{ |
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public static function normalize($html, $base_level = 1) |
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{ |
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if (!self::htmlContainsHeadings($html)) { |
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return $html; |
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} |
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$domDocument = new \DOMDocument(); |
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$domDocument->loadHTML($html); |
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$headingTagNames = ['h1', 'h2', 'h3', 'h4', 'h6']; |
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$originalHeadingDomElements = []; |
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$normalizedHeadingDomElements = []; |
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foreach ($headingTagNames as $headingTagName) { |
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$headingDomElements = $domDocument->getElementsByTagName($headingTagName); |
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foreach ($headingDomElements as $headingDomElement) { |
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$currentHeadingLevel = self::headingTagNameToNumber($headingDomElement->tagName); |
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$newHeadingLevel = self::numberToHeadingLevel($base_level + $currentHeadingLevel - 1); |
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if ($newHeadingLevel !== $currentHeadingLevel) { |
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$originalHeadingDomElements[] = $headingDomElement; |
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$normalizedHeadingDomElements[] = self::cloneDomElementWithNewTagName($headingDomElement, $newHeadingLevel); |
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} |
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} |
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} |
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foreach ($originalHeadingDomElements as $i => $needle) { |
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$needle->parentNode->replaceChild($normalizedHeadingDomElements[$i], $needle); |
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} |
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return $domDocument->saveHTML(); |
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} |
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private static function htmlContainsHeadings($html) |
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{ |
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$headingNeedle = '<h'; |
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$containsHeadings = (false !== stripos($html, $headingNeedle)); |
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return $containsHeadings; |
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} |
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private static function headingTagNameToNumber($headingLevel) |
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{ |
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return substr($headingLevel, 1); |
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} |
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private static function numberToHeadingLevel($number) |
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{ |
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return 'h' . $number; |
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} |
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private static function cloneDomElementWithNewTagName(\DOMElement $sourceDomElement, $newTagName) |
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{ |
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$targetDomElement = $sourceDomElement->parentNode->ownerDocument->createElement($newTagName); |
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self::copyAttributes($sourceDomElement, $targetDomElement); |
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self::moveChildNodes($sourceDomElement, $targetDomElement); |
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return $targetDomElement; |
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} |
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private static function copyAttributes(\DOMElement $source, \DOMElement $target) |
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{ |
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foreach ($source->attributes as $attribute) { |
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$target->setAttribute($attribute->name, $attribute->value); |
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} |
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} |
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private static function moveChildNodes(\DOMElement $source, \DOMElement $target) |
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{ |
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while ($source->hasChildNodes()) { |
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// appendChild() actually moves the childNode |
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$target->appendChild($source->childNodes->item(0)); |
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} |
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} |
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} |
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