541 lines
14 KiB
PHP
541 lines
14 KiB
PHP
<?php
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namespace Soundasleep;
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class Html2Text {
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/** @return array<string, bool | string> */
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public static function defaultOptions(): array {
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return [
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'ignore_errors' => false,
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'drop_links' => false,
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'char_set' => 'auto'
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];
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}
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/**
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* Tries to convert the given HTML into a plain text format - best suited for
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* e-mail display, etc.
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*
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* <p>In particular, it tries to maintain the following features:
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* <ul>
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* <li>Links are maintained, with the 'href' copied over
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* <li>Information in the <head> is lost
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* </ul>
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*
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* @param string $html the input HTML
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* @param boolean|array<string, bool | string> $options if boolean, Ignore xml parsing errors, else ['ignore_errors' => false, 'drop_links' => false, 'char_set' => 'auto']
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* @return string the HTML converted, as best as possible, to text
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* @throws Html2TextException if the HTML could not be loaded as a {@link \DOMDocument}
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*/
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public static function convert(string $html, $options = []): string {
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if ($options === false || $options === true) {
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// Using old style (< 1.0) of passing in options
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$options = ['ignore_errors' => $options];
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}
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$options = array_merge(static::defaultOptions(), $options);
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// check all options are valid
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foreach ($options as $key => $value) {
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if (!in_array($key, array_keys(static::defaultOptions()))) {
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throw new \InvalidArgumentException("Unknown html2text option '$key'. Valid options are " . implode(',', static::defaultOptions()));
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}
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}
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$is_office_document = self::isOfficeDocument($html);
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if ($is_office_document) {
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// remove office namespace
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$html = str_replace(["<o:p>", "</o:p>"], "", $html);
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}
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$html = self::fixNewlines($html);
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// use mb_convert_encoding for legacy versions of php
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if (PHP_MAJOR_VERSION * 10 + PHP_MINOR_VERSION < 81 && mb_detect_encoding($html, "UTF-8", true)) {
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$html = mb_convert_encoding($html, "HTML-ENTITIES", "UTF-8");
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}
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$doc = self::getDocument($html, $options);
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$output = self::iterateOverNode($doc, null, false, $is_office_document, $options);
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// process output for whitespace/newlines
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$output = self::processWhitespaceNewlines($output);
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return $output;
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}
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/**
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* Unify newlines; in particular, \r\n becomes \n, and
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* then \r becomes \n. This means that all newlines (Unix, Windows, Mac)
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* all become \ns.
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*
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* @param string $text text with any number of \r, \r\n and \n combinations
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* @return string the fixed text
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*/
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public static function fixNewlines(string $text): string {
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// replace \r\n to \n
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$text = str_replace("\r\n", "\n", $text);
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// remove \rs
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$text = str_replace("\r", "\n", $text);
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return $text;
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}
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/** @return array<string> */
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public static function nbspCodes(): array {
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return [
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"\xc2\xa0",
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"\u00a0",
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];
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}
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/** @return array<string> */
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public static function zwnjCodes(): array {
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return [
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"\xe2\x80\x8c",
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"\u200c",
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];
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}
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/**
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* Remove leading or trailing spaces and excess empty lines from provided multiline text
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*
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* @param string $text multiline text any number of leading or trailing spaces or excess lines
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* @return string the fixed text
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*/
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public static function processWhitespaceNewlines(string $text): string {
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// remove excess spaces around tabs
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$text = preg_replace("/ *\t */im", "\t", $text);
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// remove leading whitespace
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$text = ltrim($text);
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// remove leading spaces on each line
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$text = preg_replace("/\n[ \t]*/im", "\n", $text);
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// convert non-breaking spaces to regular spaces to prevent output issues,
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// do it here so they do NOT get removed with other leading spaces, as they
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// are sometimes used for indentation
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$text = self::renderText($text);
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// remove trailing whitespace
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$text = rtrim($text);
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// remove trailing spaces on each line
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$text = preg_replace("/[ \t]*\n/im", "\n", $text);
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// unarmor pre blocks
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$text = self::fixNewLines($text);
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// remove unnecessary empty lines
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$text = preg_replace("/\n\n\n*/im", "\n\n", $text);
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return $text;
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}
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/**
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* Can we guess that this HTML is generated by Microsoft Office?
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*/
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public static function isOfficeDocument(string $html): bool {
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return strpos($html, "urn:schemas-microsoft-com:office") !== false;
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}
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public static function isWhitespace(string $text): bool {
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return strlen(trim(self::renderText($text), "\n\r\t ")) === 0;
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}
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/**
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* Parse HTML into a DOMDocument
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*
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* @param string $html the input HTML
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* @param array<string, bool | string> $options
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* @return \DOMDocument the parsed document tree
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*/
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private static function getDocument(string $html, array $options): \DOMDocument {
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$doc = new \DOMDocument();
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$html = trim($html);
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if (!$html) {
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// DOMDocument doesn't support empty value and throws an error
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// Return empty document instead
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return $doc;
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}
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if ($html[0] !== '<') {
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// If HTML does not begin with a tag, we put a body tag around it.
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// If we do not do this, PHP will insert a paragraph tag around
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// the first block of text for some reason which can mess up
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// the newlines. See pre.html test for an example.
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$html = '<body>' . $html . '</body>';
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}
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$header = '';
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// use char sets for modern versions of php
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if (PHP_MAJOR_VERSION * 10 + PHP_MINOR_VERSION >= 81) {
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// use specified char_set, or auto detect if not set
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$char_set = ! empty($options['char_set']) ? $options['char_set'] : 'auto';
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if ('auto' === $char_set) {
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$char_set = mb_detect_encoding($html);
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} else if (strpos($char_set, ',')) {
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mb_detect_order($char_set);
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$char_set = mb_detect_encoding($html);
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}
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// turn off error detection for Windows-1252 legacy html
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if (strpos($char_set, '1252')) {
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$options['ignore_errors'] = true;
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}
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$header = '<?xml version="1.0" encoding="' . $char_set . '">';
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}
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if (! empty($options['ignore_errors'])) {
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$doc->strictErrorChecking = false;
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$doc->recover = true;
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$doc->xmlStandalone = true;
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$old_internal_errors = libxml_use_internal_errors(true);
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$load_result = $doc->loadHTML($header . $html, LIBXML_NOWARNING | LIBXML_NOERROR | LIBXML_NONET | LIBXML_PARSEHUGE);
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libxml_use_internal_errors($old_internal_errors);
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}
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else {
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$load_result = $doc->loadHTML($header . $html);
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}
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if (!$load_result) {
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throw new Html2TextException("Could not load HTML - badly formed?", $html);
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}
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return $doc;
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}
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/**
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* Replace any special characters with simple text versions, to prevent output issues:
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* - Convert non-breaking spaces to regular spaces; and
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* - Convert zero-width non-joiners to '' (nothing).
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*
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* This is to match our goal of rendering documents as they would be rendered
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* by a browser.
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*/
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private static function renderText(string $text): string {
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$text = str_replace(self::nbspCodes(), " ", $text);
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$text = str_replace(self::zwnjCodes(), "", $text);
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return $text;
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}
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private static function nextChildName(?\DOMNode $node): ?string {
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// get the next child
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$nextNode = $node->nextSibling;
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while ($nextNode != null) {
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if ($nextNode instanceof \DOMText) {
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if (!self::isWhitespace($nextNode->wholeText)) {
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break;
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}
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}
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if ($nextNode instanceof \DOMElement) {
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break;
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}
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$nextNode = $nextNode->nextSibling;
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}
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$nextName = null;
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if (($nextNode instanceof \DOMElement || $nextNode instanceof \DOMText) && $nextNode != null) {
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$nextName = strtolower($nextNode->nodeName);
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}
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return $nextName;
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}
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/** @param array<string, bool | string> $options */
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private static function iterateOverNode(\DOMNode $node, ?string $prevName, bool $in_pre, bool $is_office_document, array $options): string {
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if ($node instanceof \DOMText) {
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// Replace whitespace characters with a space (equivilant to \s)
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if ($in_pre) {
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$text = "\n" . trim(self::renderText($node->wholeText), "\n\r\t ") . "\n";
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// Remove trailing whitespace only
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$text = preg_replace("/[ \t]*\n/im", "\n", $text);
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// armor newlines with \r.
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return str_replace("\n", "\r", $text);
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}
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$text = self::renderText($node->wholeText);
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$text = preg_replace("/[\\t\\n\\f\\r ]+/im", " ", $text);
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if (!self::isWhitespace($text) && ($prevName == 'p' || $prevName == 'div')) {
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return "\n" . $text;
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}
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return $text;
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}
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if ($node instanceof \DOMDocumentType || $node instanceof \DOMProcessingInstruction) {
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// ignore
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return "";
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}
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$name = strtolower($node->nodeName);
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$nextName = self::nextChildName($node);
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// start whitespace
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switch ($name) {
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case "hr":
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$prefix = '';
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if ($prevName != null) {
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$prefix = "\n";
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}
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return $prefix . "---------------------------------------------------------------\n";
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case "style":
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case "head":
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case "title":
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case "meta":
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case "script":
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// ignore these tags
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return "";
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case "h1":
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case "h2":
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case "h3":
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case "h4":
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case "h5":
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case "h6":
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case "ol":
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case "ul":
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case "pre":
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// add two newlines
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$output = "\n\n";
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break;
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case "td":
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case "th":
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// add tab char to separate table fields
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$output = "\t";
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break;
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case "p":
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// Microsoft exchange emails often include HTML which, when passed through
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// html2text, results in lots of double line returns everywhere.
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//
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// To fix this, for any p element with a className of `MsoNormal` (the standard
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// classname in any Microsoft export or outlook for a paragraph that behaves
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// like a line return) we skip the first line returns and set the name to br.
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// @phpstan-ignore-next-line
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if ($is_office_document && $node->getAttribute('class') == 'MsoNormal') {
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$output = "";
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$name = 'br';
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break;
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}
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// add two lines
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$output = "\n\n";
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break;
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case "tr":
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// add one line
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$output = "\n";
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break;
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case "div":
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$output = "";
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if ($prevName !== null) {
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// add one line
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$output .= "\n";
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}
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break;
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case "li":
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$output = "- ";
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break;
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default:
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// print out contents of unknown tags
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$output = "";
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break;
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}
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// debug
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//$output .= "[$name,$nextName]";
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if (isset($node->childNodes)) {
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$n = $node->childNodes->item(0);
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$previousSiblingNames = [];
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$previousSiblingName = null;
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$parts = [];
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$trailing_whitespace = 0;
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while ($n != null) {
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$text = self::iterateOverNode($n, $previousSiblingName, $in_pre || $name == 'pre', $is_office_document, $options);
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// Pass current node name to next child, as previousSibling does not appear to get populated
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if ($n instanceof \DOMDocumentType
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|| $n instanceof \DOMProcessingInstruction
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|| ($n instanceof \DOMText && self::isWhitespace($text))) {
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// Keep current previousSiblingName, these are invisible
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$trailing_whitespace++;
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}
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else {
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$previousSiblingName = strtolower($n->nodeName);
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$previousSiblingNames[] = $previousSiblingName;
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$trailing_whitespace = 0;
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}
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$node->removeChild($n);
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$n = $node->childNodes->item(0);
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$parts[] = $text;
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}
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// Remove trailing whitespace, important for the br check below
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while ($trailing_whitespace-- > 0) {
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array_pop($parts);
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}
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// suppress last br tag inside a node list if follows text
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$last_name = array_pop($previousSiblingNames);
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if ($last_name === 'br') {
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$last_name = array_pop($previousSiblingNames);
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if ($last_name === '#text') {
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array_pop($parts);
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}
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}
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$output .= implode('', $parts);
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}
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// end whitespace
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switch ($name) {
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case "h1":
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case "h2":
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case "h3":
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case "h4":
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case "h5":
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case "h6":
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case "pre":
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case "p":
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// add two lines
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$output .= "\n\n";
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break;
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case "br":
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// add one line
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$output .= "\n";
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break;
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case "div":
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break;
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case "a":
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// links are returned in [text](link) format
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// @phpstan-ignore-next-line
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$href = $node->getAttribute("href");
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$output = trim($output);
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// remove double [[ ]] s from linking images
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if (substr($output, 0, 1) == "[" && substr($output, -1) == "]") {
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$output = substr($output, 1, strlen($output) - 2);
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// for linking images, the title of the <a> overrides the title of the <img>
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// @phpstan-ignore-next-line
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if ($node->getAttribute("title")) {
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// @phpstan-ignore-next-line
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$output = $node->getAttribute("title");
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}
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}
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// if there is no link text, but a title attr
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// @phpstan-ignore-next-line
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if (!$output && $node->getAttribute("title")) {
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// @phpstan-ignore-next-line
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$output = $node->getAttribute("title");
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}
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if ($href == null) {
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// it doesn't link anywhere
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// @phpstan-ignore-next-line
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if ($node->getAttribute("name") != null) {
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if ($options['drop_links']) {
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$output = "$output";
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} else {
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$output = "[$output]";
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}
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}
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} else {
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if ($href == $output || $href == "mailto:$output" || $href == "http://$output" || $href == "https://$output") {
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// link to the same address: just use link
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$output = "$output";
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} else {
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// replace it
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if ($output) {
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if ($options['drop_links']) {
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$output = "$output";
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} else {
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$output = "[$output]($href)";
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}
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} else {
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// empty string
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$output = "$href";
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}
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}
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}
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// does the next node require additional whitespace?
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switch ($nextName) {
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case "h1": case "h2": case "h3": case "h4": case "h5": case "h6":
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$output .= "\n";
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break;
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}
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break;
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case "img":
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// @phpstan-ignore-next-line
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if ($node->getAttribute("title")) {
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// @phpstan-ignore-next-line
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$output = "[" . $node->getAttribute("title") . "]";
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// @phpstan-ignore-next-line
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} elseif ($node->getAttribute("alt")) {
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// @phpstan-ignore-next-line
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$output = "[" . $node->getAttribute("alt") . "]";
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} else {
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$output = "";
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}
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break;
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case "li":
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$output .= "\n";
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break;
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case "blockquote":
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// process quoted text for whitespace/newlines
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$output = self::processWhitespaceNewlines($output);
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// add leading newline
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$output = "\n" . $output;
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// prepend '> ' at the beginning of all lines
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$output = preg_replace("/\n/im", "\n> ", $output);
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// replace leading '> >' with '>>'
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$output = preg_replace("/\n> >/im", "\n>>", $output);
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// add another leading newline and trailing newlines
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$output = "\n" . $output . "\n\n";
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break;
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default:
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// do nothing
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}
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return $output;
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}
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}
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