mirror of
https://gerrit.wikimedia.org/r/mediawiki/extensions/AbuseFilter.git
synced 2024-11-15 18:19:38 +00:00
284 lines
7 KiB
PHP
284 lines
7 KiB
PHP
<?php
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use MediaWiki\Logger\LoggerFactory;
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/**
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* Tokenizer for AbuseFilter rules.
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*/
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class AbuseFilterTokenizer {
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/** @var int Tokenizer cache version. Increment this when changing the syntax. **/
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const CACHE_VERSION = 1;
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const COMMENT_START_RE = '/\s*\/\*/A';
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const ID_SYMBOL_RE = '/[0-9A-Za-z_]+/A';
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const OPERATOR_RE =
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'/(\!\=\=|\!\=|\!|\*\*|\*|\/|\+|\-|%|&|\||\^|\:\=|\?|\:|\<\=|\<|\>\=|\>|\=\=\=|\=\=|\=)/A';
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const RADIX_RE = '/([0-9A-Fa-f]+(?:\.\d*)?|\.\d+)([bxo])?(?![a-z])/Au';
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const WHITESPACE = "\011\012\013\014\015\040";
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// Order is important. The punctuation-matching regex requires that
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// ** comes before *, etc. They are sorted to make it easy to spot
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// such errors.
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public static $operators = [
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// Inequality
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'!==', '!=', '!',
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// Multiplication/exponentiation
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'**', '*',
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// Other arithmetic
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'/', '+', '-', '%',
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// Logic
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'&', '|', '^',
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// Setting
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':=',
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// Ternary
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'?', ':',
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// Less than
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'<=', '<',
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// Greater than
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'>=', '>',
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// Equality
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'===', '==', '=',
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];
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public static $punctuation = [
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',' => AFPToken::TCOMMA,
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'(' => AFPToken::TBRACE,
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')' => AFPToken::TBRACE,
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'[' => AFPToken::TSQUAREBRACKET,
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']' => AFPToken::TSQUAREBRACKET,
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';' => AFPToken::TSTATEMENTSEPARATOR,
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];
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public static $bases = [
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'b' => 2,
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'x' => 16,
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'o' => 8
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];
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public static $baseCharsRe = [
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2 => '/^[01]+$/',
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8 => '/^[0-8]+$/',
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16 => '/^[0-9A-Fa-f]+$/',
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10 => '/^[0-9.]+$/',
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];
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public static $keywords = [
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'in', 'like', 'true', 'false', 'null', 'contains', 'matches',
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'rlike', 'irlike', 'regex', 'if', 'then', 'else', 'end',
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];
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/**
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* Get a cache key used to store the tokenized code
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*
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* @param BagOStuff $cache
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* @param string $code Not yet tokenized
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* @return string
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* @internal
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*/
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public static function getCacheKey( BagOStuff $cache, $code ) {
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return $cache->makeGlobalKey( __CLASS__, self::CACHE_VERSION, crc32( $code ) );
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}
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/**
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* Get the tokens for the given code.
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*
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* @param string $code
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* @return array[]
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*/
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public static function getTokens( $code ) {
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$cache = ObjectCache::getLocalServerInstance( 'hash' );
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$tokens = $cache->getWithSetCallback(
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self::getCacheKey( $cache, $code ),
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$cache::TTL_DAY,
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function () use ( $code ) {
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return self::tokenize( $code );
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}
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);
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return $tokens;
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}
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/**
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* @param string $code
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* @return array[]
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*/
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private static function tokenize( $code ) {
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$tokens = [];
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$curPos = 0;
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do {
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$prevPos = $curPos;
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$token = self::nextToken( $code, $curPos );
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$tokens[ $token->pos ] = [ $token, $curPos ];
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} while ( $curPos !== $prevPos );
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return $tokens;
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}
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/**
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* @param string $code
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* @param int &$offset
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* @return AFPToken
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* @throws AFPException
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* @throws AFPUserVisibleException
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*/
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protected static function nextToken( $code, &$offset ) {
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$matches = [];
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$start = $offset;
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// Read past comments
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while ( preg_match( self::COMMENT_START_RE, $code, $matches, 0, $offset ) ) {
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if ( strpos( $code, '*/', $offset ) === false ) {
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throw new AFPUserVisibleException(
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'unclosedcomment', $offset, [] );
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}
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$offset = strpos( $code, '*/', $offset ) + 2;
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}
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// Spaces
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$offset += strspn( $code, self::WHITESPACE, $offset );
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if ( $offset >= strlen( $code ) ) {
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return new AFPToken( AFPToken::TNONE, '', $start );
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}
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$chr = $code[$offset];
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// Punctuation
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if ( isset( self::$punctuation[$chr] ) ) {
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$offset++;
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return new AFPToken( self::$punctuation[$chr], $chr, $start );
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}
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// String literal
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if ( $chr === '"' || $chr === "'" ) {
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return self::readStringLiteral( $code, $offset, $start );
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}
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$matches = [];
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// Operators
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if ( preg_match( self::OPERATOR_RE, $code, $matches, 0, $offset ) ) {
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$token = $matches[0];
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$offset += strlen( $token );
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return new AFPToken( AFPToken::TOP, $token, $start );
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}
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// Numbers
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if ( preg_match( self::RADIX_RE, $code, $matches, 0, $offset ) ) {
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list( $token, $input ) = $matches;
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$baseChar = $matches[2] ?? null;
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// Sometimes the base char gets mixed in with the rest of it because
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// the regex targets hex, too.
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// This mostly happens with binary
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if ( !$baseChar && !empty( self::$bases[ substr( $input, - 1 ) ] ) ) {
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$baseChar = substr( $input, - 1, 1 );
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$input = substr( $input, 0, - 1 );
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}
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$base = $baseChar ? self::$bases[$baseChar] : 10;
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// Check against the appropriate character class for input validation
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if ( preg_match( self::$baseCharsRe[$base], $input ) ) {
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if ( $base !== 10 ) {
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// Our syntax is awful. Keep track of every use, and possibly change it!
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$logger = LoggerFactory::getInstance( 'AbuseFilter' );
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$logger->info(
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'Found non-decimal number. Base: {number_base}, number: {number_input}',
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[ 'number_base' => $base, 'number_input' => $input ]
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);
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}
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$num = $base !== 10 ? base_convert( $input, $base, 10 ) : $input;
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$offset += strlen( $token );
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return ( strpos( $input, '.' ) !== false )
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? new AFPToken( AFPToken::TFLOAT, floatval( $num ), $start )
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: new AFPToken( AFPToken::TINT, intval( $num ), $start );
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}
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}
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// IDs / Keywords
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if ( preg_match( self::ID_SYMBOL_RE, $code, $matches, 0, $offset ) ) {
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$token = $matches[0];
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$offset += strlen( $token );
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$type = in_array( $token, self::$keywords )
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? AFPToken::TKEYWORD
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: AFPToken::TID;
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return new AFPToken( $type, $token, $start );
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}
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throw new AFPUserVisibleException(
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'unrecognisedtoken', $start, [ substr( $code, $start ) ] );
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}
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/**
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* @param string $code
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* @param int &$offset
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* @param int $start
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* @return AFPToken
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* @throws AFPException
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* @throws AFPUserVisibleException
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*/
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protected static function readStringLiteral( $code, &$offset, $start ) {
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$type = $code[$offset];
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$offset++;
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$length = strlen( $code );
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$token = '';
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while ( $offset < $length ) {
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if ( $code[$offset] === $type ) {
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$offset++;
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return new AFPToken( AFPToken::TSTRING, $token, $start );
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}
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// Performance: Use a PHP function (implemented in C)
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// to scan ahead.
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$addLength = strcspn( $code, $type . "\\", $offset );
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if ( $addLength ) {
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$token .= substr( $code, $offset, $addLength );
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$offset += $addLength;
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} elseif ( $code[$offset] === '\\' ) {
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switch ( $code[$offset + 1] ) {
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case '\\':
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$token .= '\\';
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break;
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case $type:
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$token .= $type;
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break;
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case 'n';
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$token .= "\n";
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break;
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case 'r':
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$token .= "\r";
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break;
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case 't':
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$token .= "\t";
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break;
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case 'x':
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$chr = substr( $code, $offset + 2, 2 );
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if ( preg_match( '/^[0-9A-Fa-f]{2}$/', $chr ) ) {
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$token .= chr( hexdec( $chr ) );
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// \xXX -- 2 done later
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$offset += 2;
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} else {
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$token .= 'x';
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}
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break;
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default:
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$token .= "\\" . $code[$offset + 1];
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}
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$offset += 2;
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} else {
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// Should never happen
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// @codeCoverageIgnoreStart
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$token .= $code[$offset];
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$offset++;
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// @codeCoverageIgnoreEnd
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}
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}
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throw new AFPUserVisibleException( 'unclosedstring', $offset, [] );
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}
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}
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