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 $this->getPointerInstance()->determineSeekPosition();
 131         }
 132
 133         /**
 134          * Advances to next "block" of bytes
 135          *
 136          * @return      void
 137          * @todo        This method will load large but empty files in a whole
 138          */
 139         public function next () {
 140                 // Is there nothing to read?
 141                 if (!$this->valid()) {
 142                         // Nothing to read
 143                         return;
 144                 } // END - if
 145
 146                 // First calculate minimum block length
 147                 $length = $this->getBlockInstance()->caluclateMinimumBlockLength();
 148
 149                 // Short be more than zero!
 150                 assert($length > 0);
 151
 152                 // Wait until a entry/block separator has been found
 153                 $data = $this->getBackBuffer();
 154                 while ((!$this->getPointerInstance()->isEndOfFileReached()) && (!$this->getBlockInstance()->isBlockSeparatorFound($data))) {
 155                         // Then read the block
 156                         $data .= $this->read($length);
 157                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('data()=' . strlen($data));
 158                 } // END - if
 159
 160                 // EOF reached?
 161                 if ($this->getPointerInstance()->isEndOfFileReached()) {
 162                         // Set whole data as current block
 163                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('Calling setCurrentBlock(' . strlen($data) . ') ...');
 164                         $this->setCurrentBlock($data);
 165
 166                         // Then abort here silently
 167                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('EOF reached.');
 168                         return;
 169                 } // END - if
 170
 171                 /*
 172                  * Init back-buffer which is the data that has been found beyond the
 173                  * separator.
 174                  */
 175                 $this->initBackBuffer();
 176
 177                 // Separate data
 178                 $dataArray = explode(self::getBlockSeparator(), $data);
 179
 180                 // This array must contain two elements
 181                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('dataArray=' . print_r($dataArray, TRUE));
 182                 assert(count($dataArray) == 2);
 183
 184                 // Left part is the actual block, right one the back-buffer data
 185                 $this->setCurrentBlock($dataArray[0]);
 186                 $this->setBackBuffer($dataArray[1]);
 187         }
 188
 189         /**
 190          * Rewinds to the beginning of the file
 191          *
 192          * @return      $status         Status of this operation
 193          */
 194         public function rewind () {
 195                 // Call pointer instance
 196                 return $this->getPointerInstance()->rewind();
 197         }
 198
 199         /**
 200          * Checks wether the current entry is valid (not at the end of the file).
 201          * This method will return TRUE if an emptied (nulled) entry has been found.
 202          *
 203          * @return      $isValid        Whether the next entry is valid
 204          */
 205         public function valid () {
 206                 // First calculate minimum block length
 207                 $length = $this->getBlockInstance()->caluclateMinimumBlockLength();
 208
 209                 // Short be more than zero!
 210                 assert($length > 0);
 211
 212                 // Get current seek position
 213                 $seekPosition = $this->key();
 214
 215                 // Then try to read it
 216                 $data = $this->read($length);
 217
 218                 // If some bytes could be read, all is fine
 219                 $isValid = ((is_string($data)) && (strlen($data) > 0));
 220
 221                 // Get header size
 222                 $headerSize = $this->getBlockInstance()->getHeaderSize();
 223
 224                 // Is the seek position at or beyond the header?
 225                 if ($seekPosition >= $headerSize) {
 226                         // Seek back to old position
 227                         $this->seek($seekPosition);
 228                 } else {
 229                         // Seek directly behind the header
 230                         $this->seek($headerSize);
 231                 }
 232
 233                 // Return result
 234                 return $isValid;
 235         }
 236
 237         /**
 238          * Seeks to given position
 239          *
 240          * @param       $seekPosition   Seek position in file
 241          * @return      $status                 Status of this operation
 242          */
 243         public function seek ($seekPosition) {
 244                 // Call pointer instance
 245                 return $this->getPointerInstance()->seek($seekPosition);
 246         }
 247
 248         /**
 249          * Writes at given position by seeking to it.
 250          *
 251          * @param       $seekPosition   Seek position in file
 252          * @param       $data                   Data to be written
 253          * @return      void
 254          */
 255         public function writeAtPosition ($seekPosition, $data) {
 256                 // First seek to it
 257                 $this->seek($seekPosition);
 258
 259                 // Then write the data at that position
 260                 $this->getPointerInstance()->writeToFile($data);
 261         }
 262
 263         /**
 264          * Size of file stack
 265          *
 266          * @return      $size   Size (in bytes) of file
 267          */
 268         public function size () {
 269                 // Call the pointer object
 270                 $size = $this->getPointerInstance()->size();
 271
 272                 // Return result
 273                 return $size;
 274         }
 275
 276         /**
 277          * Reads given amount of bytes from file.
 278          *
 279          * @param       $bytes  Amount of bytes to read
 280          * @return      $data   Data read from file
 281          */
 282         public function read ($bytes) {
 283                 // Call pointer instance
 284                 return $this->getPointerInstance()->read($bytes);
 285         }
 286
 287         /**
 288          * Analyzes entries in index file. This will count all found (and valid)
 289          * entries, mark invalid as damaged and count gaps ("fragmentation"). If
 290          * only gaps are found, the file is considered as "virgin" (no entries).
 291          *
 292          * @return      void
 293          */
 294         public function analyzeFile () {
 295                 // Just call the pointer instance
 296                 $this->getPointerInstance()->analyzeFile();
 297         }
 298 }
 299
 300 // [EOF]
 301 ?>