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PhutilRemarkupBlockStorage.php
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PhutilRemarkupBlockStorage.php
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<?php
/**
* Remarkup prevents several classes of text-processing problems by replacing
* tokens in the text as they are marked up. For example, if you write something
* like this:
*
* //D12//
*
* It is processed in several stages. First the "D12" matches and is replaced
* with a token, in the form of "<0x01><ID number><literal "Z">". The first
* byte, "<0x01>" is a single byte with value 1 that marks a token. If this is
* token ID "444", the text may now look like this:
*
* //<0x01>444Z//
*
* Now the italics match and are replaced, using the next token ID:
*
* <0x01>445Z
*
* When processing completes, all the tokens are replaced with their final
* equivalents. For example, token 444 is evaluated to:
*
* <a href="http://...">...</a>
*
* Then token 445 is evaluated:
*
* <em><0x01>444Z</em>
*
* ...and all tokens it contains are replaced:
*
* <em><a href="http://...">...</a></em>
*
* If we didn't do this, the italics rule could match the "//" in "http://",
* or any other number of processing mistakes could occur, some of which create
* security risks.
*
* This class generates keys, and stores the map of keys to replacement text.
*/
final class PhutilRemarkupBlockStorage extends Phobject {
const MAGIC_BYTE = "\1";
private $map = array();
private $index = 0;
public function store($text) {
$key = self::MAGIC_BYTE.(++$this->index).'Z';
$this->map[$key] = $text;
return $key;
}
public function restore($corpus, $text_mode = false) {
$map = $this->map;
if (!$text_mode) {
foreach ($map as $key => $content) {
$map[$key] = phutil_escape_html($content);
}
$corpus = phutil_escape_html($corpus);
}
// NOTE: Tokens may contain other tokens: for example, a table may have
// links inside it. So we can't do a single simple find/replace, because
// we need to find and replace child tokens inside the content of parent
// tokens.
// However, we know that rules which have child tokens must always store
// all their child tokens first, before they store their parent token: you
// have to pass the "store(text)" API a block of text with tokens already
// in it, so you must have created child tokens already.
// Thus, all child tokens will appear in the list before parent tokens, so
// if we start at the beginning of the list and replace all the tokens we
// find in each piece of content, we'll end up expanding all subtokens
// correctly.
$map[] = $corpus;
$seen = array();
foreach ($map as $key => $content) {
$seen[$key] = true;
// If the content contains no token magic, we don't need to replace
// anything.
if (strpos($content, self::MAGIC_BYTE) === false) {
continue;
}
$matches = null;
preg_match_all(
'/'.self::MAGIC_BYTE.'\d+Z/',
$content,
$matches,
PREG_OFFSET_CAPTURE);
$matches = $matches[0];
// See PHI1114. We're replacing all the matches in one pass because this
// is significantly faster than doing "substr_replace()" in a loop if the
// corpus is large and we have a large number of matches.
// Build a list of string pieces in "$parts" by interleaving the
// plain strings between each token and the replacement token text, then
// implode the whole thing when we're done.
$parts = array();
$pos = 0;
foreach ($matches as $next) {
$subkey = $next[0];
// If we've matched a token pattern but don't actually have any
// corresponding token, just skip this match. This should not be
// possible, and should perhaps be an error.
if (!isset($seen[$subkey])) {
if (!isset($map[$subkey])) {
throw new Exception(
pht(
'Matched token key "%s" while processing remarkup block, but '.
'this token does not exist in the token map.',
$subkey));
} else {
throw new Exception(
pht(
'Matched token key "%s" while processing remarkup block, but '.
'this token appears later in the list than the key being '.
'processed ("%s").',
$subkey,
$key));
}
}
$subpos = $next[1];
// If there were any non-token bytes since the last token, add them.
if ($subpos > $pos) {
$parts[] = substr($content, $pos, $subpos - $pos);
}
// Add the token replacement text.
$parts[] = $map[$subkey];
// Move the non-token cursor forward over the token.
$pos = $subpos + strlen($subkey);
}
// Add any leftover non-token bytes after the last token.
$parts[] = substr($content, $pos);
$content = implode('', $parts);
$map[$key] = $content;
}
$corpus = last($map);
if (!$text_mode) {
$corpus = phutil_safe_html($corpus);
}
return $corpus;
}
public function overwrite($key, $new_text) {
$this->map[$key] = $new_text;
return $this;
}
public function getMap() {
return $this->map;
}
public function setMap(array $map) {
$this->map = $map;
return $this;
}
}

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