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         /** @var string */
  32         private $subject;
  33
  34         /** @var int */
  35         private $subjectLength;
  36
  37         /** @var string */
  38         private $delim;
  39
  40         /** @var int */
  41         private $delimLength;
  42
  43         /** @var int|false The position of the start of the line */
  44         private $curPos;
  45
  46         /** @var int|false The position after the end of the next delimiter */
  47         private $endPos;
  48
  49         /** @var string|false The current token */
  50         private $current;
  51
  52         /**
  53          * Construct a DelimIterator
  54          * @param string $delim
  55          * @param string $subject
  56          */
  57         public function __construct( $delim, $subject ) {
  58                 $this->subject = $subject;
  59                 $this->delim = $delim;
  60
  61                 // Micro-optimisation (theoretical)
  62                 $this->subjectLength = strlen( $subject );
  63                 $this->delimLength = strlen( $delim );
  64
  65                 $this->rewind();
  66         }
  67
  68         public function rewind(): void {
  69                 $this->curPos = 0;
  70                 $this->endPos = strpos( $this->subject, $this->delim );
  71                 $this->refreshCurrent();
  72         }
  73
  74         public function refreshCurrent() {
  75                 if ( $this->curPos === false ) {
  76                         $this->current = false;
  77                 } elseif ( $this->curPos >= $this->subjectLength ) {
  78                         $this->current = '';
  79                 } elseif ( $this->endPos === false ) {
  80                         $this->current = substr( $this->subject, $this->curPos );
  81                 } else {
  82                         $this->current = substr( $this->subject, $this->curPos, $this->endPos - $this->curPos );
  83                 }
  84         }
  85
  86         /**
  87          * @return string|false
  88          */
  89         #[\ReturnTypeWillChange]
  90         public function current() {
  91                 return $this->current;
  92         }
  93
  94         /**
  95          * @return int|false Current position or boolean false if invalid
  96          */
  97         #[\ReturnTypeWillChange]
  98         public function key() {
  99                 return $this->curPos;
 100         }
 101
 102         public function next(): void {
 103                 if ( $this->endPos === false ) {
 104                         $this->curPos = false;
 105                 } else {
 106                         $this->curPos = $this->endPos + $this->delimLength;
 107                         if ( $this->curPos >= $this->subjectLength ) {
 108                                 $this->endPos = false;
 109                         } else {
 110                                 $this->endPos = strpos( $this->subject, $this->delim, $this->curPos );
 111                         }
 112                 }
 113                 $this->refreshCurrent();
 114         }
 115
 116         public function valid(): bool {
 117                 return $this->curPos !== false;
 118         }
 119 }