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+<?php
+/**
+ * Methods to play with strings.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ * http://www.gnu.org/copyleft/gpl.html
+ *
+ * @file
+ */
+
+/**
+ * A collection of static methods to play with strings.
+ */
+class StringUtils {
+ /**
+ * Test whether a string is valid UTF-8.
+ *
+ * The function check for invalid byte sequences, overlong encoding but
+ * not for different normalisations.
+ *
+ * This relies internally on the mbstring function mb_check_encoding()
+ * hardcoded to check against UTF-8. Whenever the function is not available
+ * we fallback to a pure PHP implementation. Setting $disableMbstring to
+ * true will skip the use of mb_check_encoding, this is mostly intended for
+ * unit testing our internal implementation.
+ *
+ * @since 1.21
+ * @note In MediaWiki 1.21, this function did not provide proper UTF-8 validation.
+ * In particular, the pure PHP code path did not in fact check for overlong forms.
+ * Beware of this when backporting code to that version of MediaWiki.
+ *
+ * @param string $value String to check
+ * @param bool $disableMbstring Whether to use the pure PHP
+ * implementation instead of trying mb_check_encoding. Intended for unit
+ * testing. Default: false
+ *
+ * @return bool Whether the given $value is a valid UTF-8 encoded string
+ */
+ static function isUtf8( $value, $disableMbstring = false ) {
+ $value = (string)$value;
+
+ // If the mbstring extension is loaded, use it. However, before PHP 5.4, values above
+ // U+10FFFF are incorrectly allowed, so we have to check for them separately.
+ if ( !$disableMbstring && function_exists( 'mb_check_encoding' ) ) {
+ static $newPHP;
+ if ( $newPHP === null ) {
+ $newPHP = !mb_check_encoding( "\xf4\x90\x80\x80", 'UTF-8' );
+ }
+
+ return mb_check_encoding( $value, 'UTF-8' ) &&
+ ( $newPHP || preg_match( "/\xf4[\x90-\xbf]|[\xf5-\xff]/S", $value ) === 0 );
+ }
+
+ if ( preg_match( "/[\x80-\xff]/S", $value ) === 0 ) {
+ // String contains only ASCII characters, has to be valid
+ return true;
+ }
+
+ // PCRE implements repetition using recursion; to avoid a stack overflow (and segfault)
+ // for large input, we check for invalid sequences (<= 5 bytes) rather than valid
+ // sequences, which can be as long as the input string is. Multiple short regexes are
+ // used rather than a single long regex for performance.
+ static $regexes;
+ if ( $regexes === null ) {
+ $cont = "[\x80-\xbf]";
+ $after = "(?!$cont)"; // "(?:[^\x80-\xbf]|$)" would work here
+ $regexes = array(
+ // Continuation byte at the start
+ "/^$cont/",
+
+ // ASCII byte followed by a continuation byte
+ "/[\\x00-\x7f]$cont/S",
+
+ // Illegal byte
+ "/[\xc0\xc1\xf5-\xff]/S",
+
+ // Invalid 2-byte sequence, or valid one then an extra continuation byte
+ "/[\xc2-\xdf](?!$cont$after)/S",
+
+ // Invalid 3-byte sequence, or valid one then an extra continuation byte
+ "/\xe0(?![\xa0-\xbf]$cont$after)/",
+ "/[\xe1-\xec\xee\xef](?!$cont{2}$after)/S",
+ "/\xed(?![\x80-\x9f]$cont$after)/",
+
+ // Invalid 4-byte sequence, or valid one then an extra continuation byte
+ "/\xf0(?![\x90-\xbf]$cont{2}$after)/",
+ "/[\xf1-\xf3](?!$cont{3}$after)/S",
+ "/\xf4(?![\x80-\x8f]$cont{2}$after)/",
+ );
+ }
+
+ foreach ( $regexes as $regex ) {
+ if ( preg_match( $regex, $value ) !== 0 ) {
+ return false;
+ }
+ }
+
+ return true;
+ }
+
+ /**
+ * Perform an operation equivalent to
+ *
+ * preg_replace( "!$startDelim(.*?)$endDelim!", $replace, $subject );
+ *
+ * except that it's worst-case O(N) instead of O(N^2)
+ *
+ * Compared to delimiterReplace(), this implementation is fast but memory-
+ * hungry and inflexible. The memory requirements are such that I don't
+ * recommend using it on anything but guaranteed small chunks of text.
+ *
+ * @param string $startDelim
+ * @param string $endDelim
+ * @param string $replace
+ * @param string $subject
+ *
+ * @return string
+ */
+ static function hungryDelimiterReplace( $startDelim, $endDelim, $replace, $subject ) {
+ $segments = explode( $startDelim, $subject );
+ $output = array_shift( $segments );
+ foreach ( $segments as $s ) {
+ $endDelimPos = strpos( $s, $endDelim );
+ if ( $endDelimPos === false ) {
+ $output .= $startDelim . $s;
+ } else {
+ $output .= $replace . substr( $s, $endDelimPos + strlen( $endDelim ) );
+ }
+ }
+
+ return $output;
+ }
+
+ /**
+ * Perform an operation equivalent to
+ *
+ * preg_replace_callback( "!$startDelim(.*)$endDelim!s$flags", $callback, $subject )
+ *
+ * This implementation is slower than hungryDelimiterReplace but uses far less
+ * memory. The delimiters are literal strings, not regular expressions.
+ *
+ * If the start delimiter ends with an initial substring of the end delimiter,
+ * e.g. in the case of C-style comments, the behavior differs from the model
+ * regex. In this implementation, the end must share no characters with the
+ * start, so e.g. /*\/ is not considered to be both the start and end of a
+ * comment. /*\/xy/*\/ is considered to be a single comment with contents /xy/.
+ *
+ * @param string $startDelim Start delimiter
+ * @param string $endDelim End delimiter
+ * @param callable $callback Function to call on each match
+ * @param string $subject
+ * @param string $flags Regular expression flags
+ * @throws MWException
+ * @return string
+ */
+ static function delimiterReplaceCallback( $startDelim, $endDelim, $callback,
+ $subject, $flags = ''
+ ) {
+ $inputPos = 0;
+ $outputPos = 0;
+ $output = '';
+ $foundStart = false;
+ $encStart = preg_quote( $startDelim, '!' );
+ $encEnd = preg_quote( $endDelim, '!' );
+ $strcmp = strpos( $flags, 'i' ) === false ? 'strcmp' : 'strcasecmp';
+ $endLength = strlen( $endDelim );
+ $m = array();
+
+ while ( $inputPos < strlen( $subject ) &&
+ preg_match( "!($encStart)|($encEnd)!S$flags", $subject, $m, PREG_OFFSET_CAPTURE, $inputPos )
+ ) {
+ $tokenOffset = $m[0][1];
+ if ( $m[1][0] != '' ) {
+ if ( $foundStart &&
+ $strcmp( $endDelim, substr( $subject, $tokenOffset, $endLength ) ) == 0
+ ) {
+ # An end match is present at the same location
+ $tokenType = 'end';
+ $tokenLength = $endLength;
+ } else {
+ $tokenType = 'start';
+ $tokenLength = strlen( $m[0][0] );
+ }
+ } elseif ( $m[2][0] != '' ) {
+ $tokenType = 'end';
+ $tokenLength = strlen( $m[0][0] );
+ } else {
+ throw new MWException( 'Invalid delimiter given to ' . __METHOD__ );
+ }
+
+ if ( $tokenType == 'start' ) {
+ # Only move the start position if we haven't already found a start
+ # This means that START START END matches outer pair
+ if ( !$foundStart ) {
+ # Found start
+ $inputPos = $tokenOffset + $tokenLength;
+ # Write out the non-matching section
+ $output .= substr( $subject, $outputPos, $tokenOffset - $outputPos );
+ $outputPos = $tokenOffset;
+ $contentPos = $inputPos;
+ $foundStart = true;
+ } else {
+ # Move the input position past the *first character* of START,
+ # to protect against missing END when it overlaps with START
+ $inputPos = $tokenOffset + 1;
+ }
+ } elseif ( $tokenType == 'end' ) {
+ if ( $foundStart ) {
+ # Found match
+ $output .= call_user_func( $callback, array(
+ substr( $subject, $outputPos, $tokenOffset + $tokenLength - $outputPos ),
+ substr( $subject, $contentPos, $tokenOffset - $contentPos )
+ ) );
+ $foundStart = false;
+ } else {
+ # Non-matching end, write it out
+ $output .= substr( $subject, $inputPos, $tokenOffset + $tokenLength - $outputPos );
+ }
+ $inputPos = $outputPos = $tokenOffset + $tokenLength;
+ } else {
+ throw new MWException( 'Invalid delimiter given to ' . __METHOD__ );
+ }
+ }
+ if ( $outputPos < strlen( $subject ) ) {
+ $output .= substr( $subject, $outputPos );
+ }
+
+ return $output;
+ }
+
+ /**
+ * Perform an operation equivalent to
+ *
+ * preg_replace( "!$startDelim(.*)$endDelim!$flags", $replace, $subject )
+ *
+ * @param string $startDelim Start delimiter regular expression
+ * @param string $endDelim End delimiter regular expression
+ * @param string $replace Replacement string. May contain $1, which will be
+ * replaced by the text between the delimiters
+ * @param string $subject String to search
+ * @param string $flags Regular expression flags
+ * @return string The string with the matches replaced
+ */
+ static function delimiterReplace( $startDelim, $endDelim, $replace, $subject, $flags = '' ) {
+ $replacer = new RegexlikeReplacer( $replace );
+
+ return self::delimiterReplaceCallback( $startDelim, $endDelim,
+ $replacer->cb(), $subject, $flags );
+ }
+
+ /**
+ * More or less "markup-safe" explode()
+ * Ignores any instances of the separator inside <...>
+ * @param string $separator
+ * @param string $text
+ * @return array
+ */
+ static function explodeMarkup( $separator, $text ) {
+ $placeholder = "\x00";
+
+ // Remove placeholder instances
+ $text = str_replace( $placeholder, '', $text );
+
+ // Replace instances of the separator inside HTML-like tags with the placeholder
+ $replacer = new DoubleReplacer( $separator, $placeholder );
+ $cleaned = StringUtils::delimiterReplaceCallback( '<', '>', $replacer->cb(), $text );
+
+ // Explode, then put the replaced separators back in
+ $items = explode( $separator, $cleaned );
+ foreach ( $items as $i => $str ) {
+ $items[$i] = str_replace( $placeholder, $separator, $str );
+ }
+
+ return $items;
+ }
+
+ /**
+ * Escape a string to make it suitable for inclusion in a preg_replace()
+ * replacement parameter.
+ *
+ * @param string $string
+ * @return string
+ */
+ static function escapeRegexReplacement( $string ) {
+ $string = str_replace( '\\', '\\\\', $string );
+ $string = str_replace( '$', '\\$', $string );
+
+ return $string;
+ }
+
+ /**
+ * Workalike for explode() with limited memory usage.
+ * Returns an Iterator
+ * @param string $separator
+ * @param string $subject
+ * @return ArrayIterator|ExplodeIterator
+ */
+ static function explode( $separator, $subject ) {
+ if ( substr_count( $subject, $separator ) > 1000 ) {
+ return new ExplodeIterator( $separator, $subject );
+ } else {
+ return new ArrayIterator( explode( $separator, $subject ) );
+ }
+ }
+}
+
+/**
+ * Base class for "replacers", objects used in preg_replace_callback() and
+ * StringUtils::delimiterReplaceCallback()
+ */
+class Replacer {
+ /**
+ * @return array
+ */
+ function cb() {
+ return array( &$this, 'replace' );
+ }
+}
+
+/**
+ * Class to replace regex matches with a string similar to that used in preg_replace()
+ */
+class RegexlikeReplacer extends Replacer {
+ private $r;
+
+ /**
+ * @param string $r
+ */
+ function __construct( $r ) {
+ $this->r = $r;
+ }
+
+ /**
+ * @param array $matches
+ * @return string
+ */
+ function replace( $matches ) {
+ $pairs = array();
+ foreach ( $matches as $i => $match ) {
+ $pairs["\$$i"] = $match;
+ }
+
+ return strtr( $this->r, $pairs );
+ }
+}
+
+/**
+ * Class to perform secondary replacement within each replacement string
+ */
+class DoubleReplacer extends Replacer {
+ /**
+ * @param mixed $from
+ * @param mixed $to
+ * @param int $index
+ */
+ function __construct( $from, $to, $index = 0 ) {
+ $this->from = $from;
+ $this->to = $to;
+ $this->index = $index;
+ }
+
+ /**
+ * @param array $matches
+ * @return mixed
+ */
+ function replace( $matches ) {
+ return str_replace( $this->from, $this->to, $matches[$this->index] );
+ }
+}
+
+/**
+ * Class to perform replacement based on a simple hashtable lookup
+ */
+class HashtableReplacer extends Replacer {
+ private $table, $index;
+
+ /**
+ * @param array $table
+ * @param int $index
+ */
+ function __construct( $table, $index = 0 ) {
+ $this->table = $table;
+ $this->index = $index;
+ }
+
+ /**
+ * @param array $matches
+ * @return mixed
+ */
+ function replace( $matches ) {
+ return $this->table[$matches[$this->index]];
+ }
+}
+
+/**
+ * Replacement array for FSS with fallback to strtr()
+ * Supports lazy initialisation of FSS resource
+ */
+class ReplacementArray {
+ private $data = false;
+ private $fss = false;
+
+ /**
+ * Create an object with the specified replacement array
+ * The array should have the same form as the replacement array for strtr()
+ * @param array $data
+ */
+ function __construct( $data = array() ) {
+ $this->data = $data;
+ }
+
+ /**
+ * @return array
+ */
+ function __sleep() {
+ return array( 'data' );
+ }
+
+ function __wakeup() {
+ $this->fss = false;
+ }
+
+ /**
+ * Set the whole replacement array at once
+ * @param array $data
+ */
+ function setArray( $data ) {
+ $this->data = $data;
+ $this->fss = false;
+ }
+
+ /**
+ * @return array|bool
+ */
+ function getArray() {
+ return $this->data;
+ }
+
+ /**
+ * Set an element of the replacement array
+ * @param string $from
+ * @param string $to
+ */
+ function setPair( $from, $to ) {
+ $this->data[$from] = $to;
+ $this->fss = false;
+ }
+
+ /**
+ * @param array $data
+ */
+ function mergeArray( $data ) {
+ $this->data = array_merge( $this->data, $data );
+ $this->fss = false;
+ }
+
+ /**
+ * @param ReplacementArray $other
+ */
+ function merge( $other ) {
+ $this->data = array_merge( $this->data, $other->data );
+ $this->fss = false;
+ }
+
+ /**
+ * @param string $from
+ */
+ function removePair( $from ) {
+ unset( $this->data[$from] );
+ $this->fss = false;
+ }
+
+ /**
+ * @param array $data
+ */
+ function removeArray( $data ) {
+ foreach ( $data as $from => $to ) {
+ $this->removePair( $from );
+ }
+ $this->fss = false;
+ }
+
+ /**
+ * @param string $subject
+ * @return string
+ */
+ function replace( $subject ) {
+ if ( function_exists( 'fss_prep_replace' ) ) {
+ wfProfileIn( __METHOD__ . '-fss' );
+ if ( $this->fss === false ) {
+ $this->fss = fss_prep_replace( $this->data );
+ }
+ $result = fss_exec_replace( $this->fss, $subject );
+ wfProfileOut( __METHOD__ . '-fss' );
+ } else {
+ wfProfileIn( __METHOD__ . '-strtr' );
+ $result = strtr( $subject, $this->data );
+ wfProfileOut( __METHOD__ . '-strtr' );
+ }
+
+ return $result;
+ }
+}
+
+/**
+ * An iterator which works exactly like:
+ *
+ * foreach ( explode( $delim, $s ) as $element ) {
+ * ...
+ * }
+ *
+ * Except it doesn't use 193 byte per element
+ */
+class ExplodeIterator implements Iterator {
+ // The subject string
+ private $subject, $subjectLength;
+
+ // The delimiter
+ private $delim, $delimLength;
+
+ // The position of the start of the line
+ private $curPos;
+
+ // The position after the end of the next delimiter
+ private $endPos;
+
+ // The current token
+ private $current;
+
+ /**
+ * Construct a DelimIterator
+ * @param string $delim
+ * @param string $subject
+ */
+ function __construct( $delim, $subject ) {
+ $this->subject = $subject;
+ $this->delim = $delim;
+
+ // Micro-optimisation (theoretical)
+ $this->subjectLength = strlen( $subject );
+ $this->delimLength = strlen( $delim );
+
+ $this->rewind();
+ }
+
+ function rewind() {
+ $this->curPos = 0;
+ $this->endPos = strpos( $this->subject, $this->delim );
+ $this->refreshCurrent();
+ }
+
+ function refreshCurrent() {
+ if ( $this->curPos === false ) {
+ $this->current = false;
+ } elseif ( $this->curPos >= $this->subjectLength ) {
+ $this->current = '';
+ } elseif ( $this->endPos === false ) {
+ $this->current = substr( $this->subject, $this->curPos );
+ } else {
+ $this->current = substr( $this->subject, $this->curPos, $this->endPos - $this->curPos );
+ }
+ }
+
+ function current() {
+ return $this->current;
+ }
+
+ /**
+ * @return int|bool Current position or boolean false if invalid
+ */
+ function key() {
+ return $this->curPos;
+ }
+
+ /**
+ * @return string
+ */
+ function next() {
+ if ( $this->endPos === false ) {
+ $this->curPos = false;
+ } else {
+ $this->curPos = $this->endPos + $this->delimLength;
+ if ( $this->curPos >= $this->subjectLength ) {
+ $this->endPos = false;
+ } else {
+ $this->endPos = strpos( $this->subject, $this->delim, $this->curPos );
+ }
+ }
+ $this->refreshCurrent();
+
+ return $this->current;
+ }
+
+ /**
+ * @return bool
+ */
+ function valid() {
+ return $this->curPos !== false;
+ }
+}
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