clarify comment

[lhc/web/wiklou.git] / includes / StringUtils.php

diff --git a/includes/StringUtils.php b/includes/StringUtils.php
index 8a0e478..374fb00 100644 (file)
--- a/includes/StringUtils.php
+++ b/includes/StringUtils.php
@@ -1,5 +1,7 @@
 <?php
-
+/**
+ * A collection of static methods to play with strings.
+ */
 class StringUtils {
        /**
         * Perform an operation equivalent to 
@@ -31,41 +33,74 @@ class StringUtils {
         *
         *   preg_replace_callback( "!$startDelim(.*)$endDelim!s$flags", $callback, $subject )
         *
-        * This implementation is slower than staticDelimiterReplace but uses far less
-        * memory and allows regular expression delimiters.
+        * 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( $subject ) && 
-                 preg_match( "!($startDelim)|($endDelim)!$flags", $subject, $m, PREG_OFFSET_CAPTURE, $inputPos ) ) 
+                 preg_match( "!($encStart)|($encEnd)!S$flags", $subject, $m, PREG_OFFSET_CAPTURE, $inputPos ) ) 
                {
+                       $tokenOffset = $m[0][1];
                        if ( $m[1][0] != '' ) {
-                               # Found start
-                               # Write out the non-matching section
-                               $output .= substr( $subject, $outputPos, $m[1][1] - $outputPos );
-                               $foundStart = true;
-                               $inputPos = $contentPos = $m[1][1] + strlen( $m[1][0] );
-                               $outputPos = $m[1][1];
+                               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] != '' ) {
-                               # Found end
+                               $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, $m[2][1] + strlen( $m[2][0] ) - $outputPos ),
-                                               substr( $subject, $contentPos, $m[2][1] - $contentPos )
+                                               substr( $subject, $outputPos, $tokenOffset + $tokenLength - $outputPos ),
+                                               substr( $subject, $contentPos, $tokenOffset - $contentPos )
                                        ));
                                        $foundStart = false;
                                } else {
                                        # Non-matching end, write it out
-                                       $output .= substr( $subject, $inputPos, $m[2][1] + strlen( $m[2][0] ) - $outputPos );
+                                       $output .= substr( $subject, $inputPos, $tokenOffset + $tokenLength - $outputPos );
                                }
-                               $inputPos = $outputPos = $m[2][1] + strlen( $m[2][0] );
+                               $inputPos = $outputPos = $tokenOffset + $tokenLength;
                        } else {
                                throw new MWException( 'Invalid delimiter given to ' . __METHOD__ );
                        }
@@ -250,14 +285,19 @@ class ReplacementArray {
 
        function replace( $subject ) {
                if ( function_exists( 'fss_prep_replace' ) ) {
+                       wfProfileIn( __METHOD__.'-fss' );
                        if ( $this->fss === false ) {
                                $this->fss = fss_prep_replace( $this->data );
                        }
-                       return fss_exec_replace( $this->fss, $subject );
+                       $result = fss_exec_replace( $this->fss, $subject );
+                       wfProfileOut( __METHOD__.'-fss' );
                } else {
-                       return strtr( $subject, $this->data );
+                       wfProfileIn( __METHOD__.'-strtr' );
+                       $result = strtr( $subject, $this->data );
+                       wfProfileOut( __METHOD__.'-strtr' );
                }
+               return $result;
        }
 }
 
-?>
+