<?php
/**
* A collection of static methods to play with strings.
*/
class StringUtils {
/**
* 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.
*/
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.
*
* @param string $flags Regular expression flags
*/
# If the start delimiter ends with an initial substring of the end delimiter,
# e.g. in the case of C-style comments, the behaviour 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/.
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' ) {
$inputPos = $tokenOffset + $tokenLength;
# Only move the start position if we haven't already found a start
# This means that START START END matches outer pair
if ( !$foundStart ) {
# Found start
# Write out the non-matching section
$output .= substr( $subject, $outputPos, $tokenOffset - $outputPos );
$outputPos = $tokenOffset;
$contentPos = $inputPos;
$foundStart = true;
}
} 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
* @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 $string;
}
}
/**
* Base class for "replacers", objects used in preg_replace_callback() and
* StringUtils::delimiterReplaceCallback()
*/
class Replacer {
function cb() {
return array( &$this, 'replace' );
}
}
/**
* Class to replace regex matches with a string similar to that used in preg_replace()
*/
class RegexlikeReplacer extends Replacer {
var $r;
function __construct( $r ) {
$this->r = $r;
}
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 {
function __construct( $from, $to, $index = 0 ) {
$this->from = $from;
$this->to = $to;
$this->index = $index;
}
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 {
var $table, $index;
function __construct( $table, $index = 0 ) {
$this->table = $table;
$this->index = $index;
}
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 {
/*mostly private*/ var $data = false;
/*mostly private*/ var $fss = false;
/**
* Create an object with the specified replacement array
* The array should have the same form as the replacement array for strtr()
*/
function __construct( $data = array() ) {
$this->data = $data;
}
function __sleep() {
return array( 'data' );
}
function __wakeup() {
$this->fss = false;
}
/**
* Set the whole replacement array at once
*/
function setArray( $data ) {
$this->data = $data;
$this->fss = false;
}
function getArray() {
return $this->data;
}
/**
* Set an element of the replacement array
*/
function setPair( $from, $to ) {
$this->data[$from] = $to;
$this->fss = false;
}
function mergeArray( $data ) {
$this->data = array_merge( $this->data, $data );
$this->fss = false;
}
function merge( $other ) {
$this->data = array_merge( $this->data, $other->data );
$this->fss = false;
}
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;
}
}
