inc/classes/main/iterator/io/class_FileIoIterator.php

   1 <?php
   2 /**
   3  * A file i/o iterator
   4  *
   5  * @author              Roland Haeder <webmaster@ship-simu.org>
   6  * @version             0.0.0
   7  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2012 Hub Developer Team
   8  * @license             GNU GPL 3.0 or any newer version
   9  * @link                http://www.ship-simu.org
  10  *
  11  * This program is free software: you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation, either version 3 of the License, or
  14  * (at your option) any later version.
  15  *
  16  * This program is distributed in the hope that it will be useful,
  17  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  18  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19  * GNU General Public License for more details.
  20  *
  21  * You should have received a copy of the GNU General Public License
  22  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  23  */
  24 class FileIoIterator extends BaseIterator implements SeekableWritableFileIterator {
  25         /**
  26          * Back-buffer
  27          */
  28         private $backBuffer = '';
  29
  30         /**
  31          * Currently loaded block (will be returned by current())
  32          */
  33         private $currentBlock = '';
  34
  35         /**
  36          * Protected constructor
  37          *
  38          * @return      void
  39          */
  40         protected function __construct () {
  41                 // Call parent constructor
  42                 parent::__construct(__CLASS__);
  43         }
  44
  45         /**
  46          * Creates an instance of this class
  47          *
  48          * @param       $pointerInstance        An instance of a InputOutputPointer class
  49          * @param       $blockInstance          An instance of a CalculatableBlock class
  50          * @return      $iteratorInstance       An instance of a Iterator class
  51          */
  52         public final static function createFileIoIterator (InputOutputPointer $pointerInstance, CalculatableBlock $blockInstance) {
  53                 // Get new instance
  54                 $iteratorInstance = new FileIoIterator();
  55
  56                 // Set the instance here
  57                 $iteratorInstance->setPointerInstance($pointerInstance);
  58
  59                 // Set the block instance here
  60                 $iteratorInstance->setBlockInstance($blockInstance);
  61
  62                 // Return the prepared instance
  63                 return $iteratorInstance;
  64         }
  65
  66         /**
  67          * Initializes the back-buffer by setting it to an empty string.
  68          *
  69          * @return      void
  70          */
  71         private function initBackBuffer () {
  72                 // Simply call the setter
  73                 $this->setBackBuffer('');
  74         }
  75
  76         /**
  77          * Setter for backBuffer field
  78          *
  79          * @param       $backBuffer             Characters to "store" in back-buffer
  80          * @return      void
  81          */
  82         private function setBackBuffer ($backBuffer) {
  83                 // Cast to string (so no arrays or objects)
  84                 $backBuffer = (string) $backBuffer;
  85
  86                 // ... and set it
  87                 $this->backBuffer = $backBuffer;
  88         }
  89
  90         /**
  91          * Getter for backBuffer field
  92          *
  93          * @return      $backBuffer             Characters "stored" in back-buffer
  94          */
  95         private function getBackBuffer () {
  96                 return $this->backBuffer;
  97         }
  98
  99         /**
 100          * Setter for currentBlock field
 101          *
 102          * @param       $currentBlock           Characters to set a currently loaded block
 103          * @return      void
 104          */
 105         private function setCurrentBlock ($currentBlock) {
 106                 // Cast to string (so no arrays or objects)
 107                 $currentBlock = (string) $currentBlock;
 108
 109                 // ... and set it
 110                 $this->currentBlock = $currentBlock;
 111         }
 112
 113         /**
 114          * Gets currently read data
 115          *
 116          * @return      $current        Currently read data
 117          */
 118         public function current () {
 119                 // Return it
 120                 return $this->currentBlock;
 121         }
 122
 123         /**
 124          * Gets current seek position ("key").
 125          *
 126          * @return      $key    Current key in iteration
 127          */
 128         public function key () {
 129                 // Return it
 130                 return $this->getPointerInstance()->determineSeekPosition();
 131         }
 132
 133         /**
 134          * Advances to next "block" of bytes
 135          *
 136          * @return      void
 137          */
 138         public function next () {
 139                 // Is there nothing to read?
 140                 if (!$this->valid()) {
 141                         // Nothing to read
 142                         return;
 143                 } // END - if
 144
 145                 // First calculate minimum block length
 146                 $length = $this->getBlockInstance()->caluclateMinimumBlockLength();
 147
 148                 // Short be more than zero!
 149                 assert($length > 0);
 150
 151                 // Wait until a entry/block separator has been found
 152                 $data = $this->getBackBuffer();
 153                 while (!$this->getBlockInstance()->isBlockSeparatorFound($data)) {
 154                         // Then read the block
 155                         $data .= $this->read($length);
 156                 } // END - if
 157
 158                 /*
 159                  * Init back-buffer which is the data that has been found beyond the
 160                  * separator.
 161                  */
 162                 $this->initBackBuffer();
 163
 164                 // Separate data
 165                 $dataArray = explode(self::getBlockSeparator(), $data);
 166
 167                 // Left part is the actual block, right one the back-buffer data
 168                 $this->setCurrentBlock($dataArray[0]);
 169                 $this->setBackBuffer($dataArray[1]);
 170         }
 171
 172         /**
 173          * Rewinds to the beginning of the file
 174          *
 175          * @return      $status         Status of this operation
 176          */
 177         public function rewind () {
 178                 // Call pointer instance
 179                 return $this->getPointerInstance()->rewind();
 180         }
 181
 182         /**
 183          * Checks wether the current entry is valid (not at the end of the file).
 184          * This method will return TRUE if an emptied (nulled) entry has been found.
 185          *
 186          * @return      $isValid        Whether the next entry is valid
 187          */
 188         public function valid () {
 189                 // First calculate minimum block length
 190                 $length = $this->getBlockInstance()->caluclateMinimumBlockLength();
 191
 192                 // Short be more than zero!
 193                 assert($length > 0);
 194
 195                 // Get current seek position
 196                 $seekPosition = $this->key();
 197
 198                 // Then try to read it
 199                 $data = $this->read($length);
 200
 201                 // If some bytes could be read, all is fine
 202                 $isValid = ((is_string($data)) && (strlen($data) > 0));
 203
 204                 // Get header size
 205                 $headerSize = $this->getBlockInstance()->getHeaderSize();
 206
 207                 // Is the seek position at or beyond the header?
 208                 if ($seekPosition >= $headerSize) {
 209                         // Seek back to old position
 210                         $this->seek($seekPosition);
 211                 } else {
 212                         // Seek directly behind the header
 213                         $this->seek($headerSize);
 214                 }
 215
 216                 // Return result
 217                 return $isValid;
 218         }
 219
 220         /**
 221          * Seeks to given position
 222          *
 223          * @param       $seekPosition   Seek position in file
 224          * @return      $status                 Status of this operation
 225          */
 226         public function seek ($seekPosition) {
 227                 // Call pointer instance
 228                 return $this->getPointerInstance()->seek($seekPosition);
 229         }
 230
 231         /**
 232          * Writes at given position by seeking to it.
 233          *
 234          * @param       $seekPosition   Seek position in file
 235          * @param       $data                   Data to be written
 236          * @return      void
 237          */
 238         public function writeAtPosition ($seekPosition, $data) {
 239                 // First seek to it
 240                 $this->seek($seekPosition);
 241
 242                 // Then write the data at that position
 243                 $this->getPointerInstance()->writeToFile($data);
 244         }
 245
 246         /**
 247          * Size of file stack
 248          *
 249          * @return      $size   Size (in bytes) of file
 250          */
 251         public function size () {
 252                 // Call the pointer object
 253                 $size = $this->getPointerInstance()->size();
 254
 255                 // Return result
 256                 return $size;
 257         }
 258
 259         /**
 260          * Reads given amount of bytes from file.
 261          *
 262          * @param       $bytes  Amount of bytes to read
 263          * @return      $data   Data read from file
 264          */
 265         public function read ($bytes) {
 266                 // Call pointer instance
 267                 return $this->getPointerInstance()->read($bytes);
 268         }
 269 }
 270
 271 // [EOF]
 272 ?>