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<?php |
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namespace allejo\stakx\Twig; |
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class TableOfContentsFilter implements StakxTwigFilter |
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{ |
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/** |
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* @param string $html The HTML we'll be parsing |
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* @param string|null $id The ID to assign to the generated TOC |
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* @param string|null $class The class to assign to the generated TOC |
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* @param int $hMin The heading minimum that'll be included |
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* @param int $hMax The heading maximum that'll be included |
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* |
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* @link https://git.io/vdnEM Modified from @mattfarina's implementation |
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* |
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* @return string |
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*/ |
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public function __invoke($html, $id = null, $class = null, $hMin = 1, $hMax = 6) |
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{ |
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if (!function_exists('simplexml_load_string')) |
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{ |
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trigger_error('XML support is not available with the current PHP installation.', E_USER_WARNING); |
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return ''; |
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} |
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$content = simplexml_load_string('<html>' . $html . '</html>'); |
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if ($content === false) |
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{ |
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trigger_error('The HTML given to generate this Table of Contents was invalid.', E_USER_WARNING); |
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return ''; |
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} |
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$toc = ''; |
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$curr = $last = 1; |
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$headings = $content->xpath('//h1|//h2|//h3|//h4|//h5|//h6'); |
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foreach ($headings as $heading) |
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{ |
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if (!property_exists($heading->attributes(), 'id')) |
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{ |
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continue; |
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} |
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sscanf($heading->getName(), 'h%u', $curr); |
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if (!($hMin <= $curr && $curr <= $hMax)) { |
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continue; |
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} |
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$headingID = $heading->attributes()->id; |
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// If the current level is greater than the last level indent one level |
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if ($curr > $last) { |
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$toc .= '<ul>'; |
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} |
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// If the current level is less than the last level go up appropriate amount. |
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elseif ($curr < $last) { |
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$toc .= str_repeat('</li></ul>', $last - $curr) . '</li>'; |
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} |
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// If the current level is equal to the last. |
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else { |
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$toc .= '</li>'; |
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} |
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$toc .= '<li><a href="#' . $headingID . '">' . (string)$heading . '</a>'; |
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$last = $curr; |
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} |
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$toc .= str_repeat('</li></ul>', $last); |
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if ($id !== null || $class !== null) |
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{ |
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$attributes = []; |
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if ($id !== null) |
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{ |
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$attributes[] = sprintf('id="%s"', $id); |
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} |
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if ($class !== null) |
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{ |
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$attributes[] = sprintf('class="%s"', $class); |
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} |
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$toc = substr_replace($toc, sprintf('<ul %s', implode(' ', $attributes)), 0, 3); |
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} |
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return $toc; |
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} |
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/** |
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* @return \Twig_SimpleFilter |
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*/ |
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public static function get() |
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{ |
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return (new \Twig_SimpleFilter('toc', new self())); |
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} |
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} |
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