includes/libs/ExplodeIterator.php

   1 <?php
   2 /**
   3  * This program is free software; you can redistribute it and/or modify
   4  * it under the terms of the GNU General Public License as published by
   5  * the Free Software Foundation; either version 2 of the License, or
   6  * (at your option) any later version.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  11  * GNU General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along
  14  * with this program; if not, write to the Free Software Foundation, Inc.,
  15  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
  16  * http://www.gnu.org/copyleft/gpl.html
  17  *
  18  * @file
  19  */
  20
  21 /**
  22  * An iterator which works exactly like:
  23  *
  24  * foreach ( explode( $delim, $s ) as $element ) {
  25  *    ...
  26  * }
  27  *
  28  * Except it doesn't use 193 byte per element
  29  */
  30 class ExplodeIterator implements Iterator {
  31         // The subject string
  32         private $subject, $subjectLength;
  33
  34         // The delimiter
  35         private $delim, $delimLength;
  36
  37         // The position of the start of the line
  38         private $curPos;
  39
  40         // The position after the end of the next delimiter
  41         private $endPos;
  42
  43         // The current token
  44         private $current;
  45
  46         /**
  47          * Construct a DelimIterator
  48          * @param string $delim
  49          * @param string $subject
  50          */
  51         public function __construct( $delim, $subject ) {
  52                 $this->subject = $subject;
  53                 $this->delim = $delim;
  54
  55                 // Micro-optimisation (theoretical)
  56                 $this->subjectLength = strlen( $subject );
  57                 $this->delimLength = strlen( $delim );
  58
  59                 $this->rewind();
  60         }
  61
  62         public function rewind() {
  63                 $this->curPos = 0;
  64                 $this->endPos = strpos( $this->subject, $this->delim );
  65                 $this->refreshCurrent();
  66         }
  67
  68         public function refreshCurrent() {
  69                 if ( $this->curPos === false ) {
  70                         $this->current = false;
  71                 } elseif ( $this->curPos >= $this->subjectLength ) {
  72                         $this->current = '';
  73                 } elseif ( $this->endPos === false ) {
  74                         $this->current = substr( $this->subject, $this->curPos );
  75                 } else {
  76                         $this->current = substr( $this->subject, $this->curPos, $this->endPos - $this->curPos );
  77                 }
  78         }
  79
  80         public function current() {
  81                 return $this->current;
  82         }
  83
  84         /**
  85          * @return int|bool Current position or boolean false if invalid
  86          */
  87         public function key() {
  88                 return $this->curPos;
  89         }
  90
  91         /**
  92          * @return string
  93          */
  94         public function next() {
  95                 if ( $this->endPos === false ) {
  96                         $this->curPos = false;
  97                 } else {
  98                         $this->curPos = $this->endPos + $this->delimLength;
  99                         if ( $this->curPos >= $this->subjectLength ) {
 100                                 $this->endPos = false;
 101                         } else {
 102                                 $this->endPos = strpos( $this->subject, $this->delim, $this->curPos );
 103                         }
 104                 }
 105                 $this->refreshCurrent();
 106
 107                 return $this->current;
 108         }
 109
 110         /**
 111          * @return bool
 112          */
 113         public function valid() {
 114                 return $this->curPos !== false;
 115         }
 116 }