inc/classes/main/file_directories/class_BaseFile.php

   1 <?php
   2 /**
   3  * A general file class
   4  *
   5  * @author              Roland Haeder <webmaster@ship-simu.org>
   6  * @version             0.0.0
   7  * @copyright   Copyright (c) 2007, 2008 Roland Haeder, 2009 - 2012 Core 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 BaseFile extends BaseFrameworkSystem {
  25         /**
  26          * Separator for header data
  27          */
  28         const SEPARATOR_HEADER_DATA = 0x01;
  29
  30         /**
  31          * Separator header->entries
  32          */
  33         const SEPARATOR_HEADER_ENTRIES = 0x02;
  34
  35         /**
  36          * Separator hash->name
  37          */
  38         const SEPARATOR_HASH_NAME = 0x03;
  39
  40         /**
  41          * Separator entry->entry
  42          */
  43         const SEPARATOR_ENTRIES = 0x04;
  44
  45         /**
  46          * Separator type->position
  47          */
  48         const SEPARATOR_TYPE_POSITION = 0x05;
  49
  50         /**
  51          * Length of count
  52          */
  53         const LENGTH_COUNT = 20;
  54
  55         /**
  56          * Length of position
  57          */
  58         const LENGTH_POSITION = 20;
  59
  60         /**
  61          * Length of name
  62          */
  63         const LENGTH_NAME = 10;
  64
  65         /**
  66          * Maximum length of entry type
  67          */
  68         const LENGTH_TYPE = 20;
  69
  70         /**
  71          * Length of output from hash()
  72          */
  73         private static $hashLength = NULL;
  74
  75         /**
  76          * Counter for total entries
  77          */
  78         private $totalEntries = 0;
  79
  80         /**
  81          * Current seek position
  82          */
  83         private $seekPosition = 0;
  84
  85         /**
  86          * Size of header
  87          */
  88         private $headerSize = 0;
  89
  90         /**
  91          * File header
  92          */
  93         private $header = array();
  94
  95         /**
  96          * Seek positions for gaps ("fragmentation")
  97          */
  98         private $gaps = array();
  99
 100         /**
 101          * Seek positions for damaged entries (e.g. mismatching hash sum, ...)
 102          */
 103         private $damagedEntries = array();
 104
 105         /**
 106          * The current file we are working in
 107          */
 108         private $fileName = '';
 109
 110         /**
 111          * Back-buffer
 112          */
 113         private $backBuffer = '';
 114
 115         /**
 116          * Currently loaded block (will be returned by current())
 117          */
 118         private $currentBlock = '';
 119
 120         /**
 121          * Protected constructor
 122          *
 123          * @param       $className      Name of the class
 124 y        * @return      void
 125          */
 126         protected function __construct ($className) {
 127                 // Call parent constructor
 128                 parent::__construct($className);
 129
 130                 // Init counters and gaps array
 131                 $this->initCountersGapsArray();
 132         }
 133
 134         /**
 135          * Destructor for cleaning purposes, etc
 136          *
 137          * @return      void
 138          */
 139         public final function __destruct() {
 140                 // Try to close a file
 141                 $this->closeFile();
 142
 143                 // Call the parent destructor
 144                 parent::__destruct();
 145         }
 146
 147         /**
 148          * Initializes counter for valid entries, arrays for damaged entries and
 149          * an array for gap seek positions. If you call this method on your own,
 150          * please re-analyze the file structure. So you are better to call
 151          * analyzeFile() instead of this method.
 152          *
 153          * @return      void
 154          */
 155         protected function initCountersGapsArray () {
 156                 // Init counter and seek position
 157                 $this->setCounter(0);
 158                 $this->setSeekPosition(0);
 159
 160                 // Init arrays
 161                 $this->gaps = array();
 162                 $this->damagedEntries = array();
 163         }
 164
 165         /**
 166          * Getter for total entries
 167          *
 168          * @return      $totalEntries   Total entries in this file
 169          */
 170         protected final function getCounter () {
 171                 // Get it
 172                 return $this->totalEntries;
 173         }
 174
 175         /**
 176          * Setter for total entries
 177          *
 178          * @param       $totalEntries   Total entries in this file
 179          * @return      void
 180          */
 181         protected final function setCounter ($counter) {
 182                 // Set it
 183                 $this->totalEntries = $counter;
 184         }
 185
 186         /**
 187          * Increment counter
 188          *
 189          * @return      void
 190          */
 191         protected final function incrementCounter () {
 192                 // Get it
 193                 $this->totalEntries++;
 194         }
 195
 196         /**
 197          * Getter for header size
 198          *
 199          * @return      $totalEntries   Size of file header
 200          */
 201         public final function getHeaderSize () {
 202                 // Get it
 203                 return $this->headerSize;
 204         }
 205
 206         /**
 207          * Setter for header size
 208          *
 209          * @param       $headerSize             Size of file header
 210          * @return      void
 211          */
 212         protected final function setHeaderSize ($headerSize) {
 213                 // Set it
 214                 $this->headerSize = $headerSize;
 215         }
 216
 217         /**
 218          * Getter for header array
 219          *
 220          * @return      $totalEntries   Size of file header
 221          */
 222         protected final function getHeade () {
 223                 // Get it
 224                 return $this->header;
 225         }
 226
 227         /**
 228          * Setter for header
 229          *
 230          * @param       $header         Array for a file header
 231          * @return      void
 232          */
 233         protected final function setHeader (array $header) {
 234                 // Set it
 235                 $this->header = $header;
 236         }
 237
 238         /**
 239          * Getter for seek position
 240          *
 241          * @return      $seekPosition   Current seek position (stored here in object)
 242          */
 243         protected final function getSeekPosition () {
 244                 // Get it
 245                 return $this->seekPosition;
 246         }
 247
 248         /**
 249          * Setter for seek position
 250          *
 251          * @param       $seekPosition   Current seek position (stored here in object)
 252          * @return      void
 253          */
 254         protected final function setSeekPosition ($seekPosition) {
 255                 // And set it
 256                 $this->seekPosition = $seekPosition;
 257         }
 258
 259         /**
 260          * Updates seekPosition attribute from file to avoid to much access on file.
 261          *
 262          * @return      void
 263          */
 264         protected function updateSeekPosition () {
 265                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 266
 267                 // Get key (= seek position)
 268                 $seekPosition = $this->getIteratorInstance()->key();
 269                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Setting seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 270
 271                 // And set it here
 272                 $this->setSeekPosition($seekPosition);
 273
 274                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 275         }
 276
 277         /**
 278          * Seeks to beginning of file, updates seek position in this object and
 279          * flushes the header.
 280          *
 281          * @return      void
 282          */
 283         protected function rewineUpdateSeekPosition () {
 284                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 285
 286                 // flushFileHeader must be callable
 287                 assert(is_callable(array($this, 'flushFileHeader')));
 288
 289                 // Seek to beginning of file
 290                 $this->getIteratorInstance()->rewind();
 291
 292                 // And update seek position ...
 293                 $this->updateSeekPosition();
 294
 295                 // ... to write it back into the file
 296                 $this->flushFileHeader();
 297
 298                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 299         }
 300
 301         /**
 302          * Seeks to old position
 303          *
 304          * @return      void
 305          */
 306         protected function seekToOldPosition () {
 307                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 308
 309                 // Seek to currently ("old") saved position
 310                 $this->getIteratorInstance()->seek($this->getSeekPosition());
 311
 312                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 313         }
 314
 315         /**
 316          * Checks whether the block separator has been found
 317          *
 318          * @param       $str            String to look in
 319          * @return      $isFound        Whether the block separator has been found
 320          */
 321         public static function isBlockSeparatorFound ($str) {
 322                 // Determine it
 323                 $isFound = (strpos($str, chr(self::SEPARATOR_ENTRIES)) !== FALSE);
 324
 325                 // Return result
 326                 return $isFound;
 327         }
 328
 329         /**
 330          * Getter for the file pointer
 331          *
 332          * @return      $filePointer    The file pointer which shall be a valid file resource
 333          * @throws      UnsupportedOperationException   If this method is called
 334          */
 335         public final function getPointer () {
 336                 throw new UnsupportedOperationException(array($this, __FUNCTION__), self::EXCEPTION_UNSPPORTED_OPERATION);
 337         }
 338
 339         /**
 340          * Setter for file name
 341          *
 342          * @param       $fileName       The new file name
 343          * @return      void
 344          */
 345         protected final function setFileName ($fileName) {
 346                 $fileName = (string) $fileName;
 347                 $this->fileName = $fileName;
 348         }
 349
 350         /**
 351          * Getter for file name
 352          *
 353          * @return      $fileName       The current file name
 354          */
 355         public final function getFileName () {
 356                 return $this->fileName;
 357         }
 358
 359         /**
 360          * Initializes the back-buffer by setting it to an empty string.
 361          *
 362          * @return      void
 363          */
 364         private function initBackBuffer () {
 365                 // Simply call the setter
 366                 $this->setBackBuffer('');
 367         }
 368
 369         /**
 370          * Setter for backBuffer field
 371          *
 372          * @param       $backBuffer             Characters to "store" in back-buffer
 373          * @return      void
 374          */
 375         private function setBackBuffer ($backBuffer) {
 376                 // Cast to string (so no arrays or objects)
 377                 $backBuffer = (string) $backBuffer;
 378
 379                 // ... and set it
 380                 $this->backBuffer = $backBuffer;
 381         }
 382
 383         /**
 384          * Getter for backBuffer field
 385          *
 386          * @return      $backBuffer             Characters "stored" in back-buffer
 387          */
 388         private function getBackBuffer () {
 389                 return $this->backBuffer;
 390         }
 391
 392         /**
 393          * Setter for currentBlock field
 394          *
 395          * @param       $currentBlock           Characters to set a currently loaded block
 396          * @return      void
 397          */
 398         private function setCurrentBlock ($currentBlock) {
 399                 // Cast to string (so no arrays or objects)
 400                 $currentBlock = (string) $currentBlock;
 401
 402                 // ... and set it
 403                 $this->currentBlock = $currentBlock;
 404         }
 405
 406         /**
 407          * Gets currently read data
 408          *
 409          * @return      $current        Currently read data
 410          */
 411         public function getCurrentBlock () {
 412                 // Return it
 413                 return $this->currentBlock;
 414         }
 415
 416         /**
 417          * Initializes this file class
 418          *
 419          * @param       $fileName       Name of this abstract file
 420          * @return      void
 421          */
 422         protected function initFile ($fileName) {
 423                 // Get a file i/o pointer instance
 424                 $pointerInstance = ObjectFactory::createObjectByConfiguredName('file_raw_input_output_class', array($fileName));
 425
 426                 // ... and set it here
 427                 $this->setPointerInstance($pointerInstance);
 428         }
 429
 430         /**
 431          * Writes data at given position
 432          *
 433          * @param       $seekPosition   Seek position
 434          * @param       $data                   Data to be written
 435          * @param       $flushHeader    Whether to flush the header (default: flush)
 436          * @return      void
 437          */
 438         protected function writeData ($seekPosition, $data, $flushHeader = TRUE) {
 439                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s,data()=%s - CALLED!', __METHOD__, __LINE__, $seekPosition, strlen($data)));
 440
 441                 // Write data at given position
 442                 $this->getPointerInstance()->writeAtPosition($seekPosition, $data);
 443
 444                 // Update seek position
 445                 $this->updateSeekPosition();
 446
 447                 // Flush the header?
 448                 if ($flushHeader === TRUE) {
 449                         // Flush header
 450                         $this->flushFileHeader();
 451
 452                         // Seek to old position
 453                         $this->seekToOldPosition();
 454                 } // END - if
 455
 456                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 457         }
 458
 459         /**
 460          * Checks whether the file header is initialized
 461          *
 462          * @return      $isInitialized  Whether the file header is initialized
 463          */
 464         public function isFileHeaderInitialized () {
 465                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 466
 467                 // Default is not initialized
 468                 $isInitialized = FALSE;
 469
 470                 // Is the file initialized?
 471                 if ($this->isFileInitialized()) {
 472                         // Some bytes has been written, so rewind to start of it.
 473                         $rewindStatus = $this->rewind();
 474                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] rewindStatus=%s', __METHOD__, __LINE__, $rewindStatus));
 475
 476                         // Is the rewind() call successfull?
 477                         if ($rewindStatus != 1) {
 478                                 // Something bad happened
 479                                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Could not rewind().', __METHOD__, __LINE__));
 480                         } // END - if
 481
 482                         // Read file header
 483                         $this->readFileHeader();
 484
 485                         // The above method does already check the header
 486                         $isInitialized = TRUE;
 487                 } // END - if
 488
 489                 // Return result
 490                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 491                 return $isInitialized;
 492         }
 493
 494         /**
 495          * Checks whether the assigned file has been initialized
 496          *
 497          * @return      $isInitialized          Whether the file's size is zero
 498          */
 499         public function isFileInitialized () {
 500                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 501
 502                 // Get it from iterator which holds the pointer instance. If FALSE is returned
 503                 $fileSize = $this->size();
 504                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] fileSize=%s', __METHOD__, __LINE__, $fileSize));
 505
 506                 /*
 507                  * The returned file size should not be FALSE or NULL as this means
 508                  * that the pointer class does not work correctly.
 509                  */
 510                 assert(is_int($fileSize));
 511
 512                 // Is more than 0 returned?
 513                 $isInitialized = ($fileSize > 0);
 514
 515                 // Return result
 516                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] isInitialized=%d - EXIT!', __METHOD__, __LINE__, intval($isInitialized)));
 517                 return $isInitialized;
 518         }
 519
 520         /**
 521          * Creates the assigned file
 522          *
 523          * @return      void
 524          */
 525         public function createFileHeader () {
 526                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 527
 528                 // The file's header should not be initialized here
 529                 assert(!$this->isFileHeaderInitialized());
 530
 531                 // Simple flush file header which will create it.
 532                 $this->flushFileHeader();
 533
 534                 // Rewind seek position (to beginning of file) and update/flush file header
 535                 $this->rewineUpdateSeekPosition();
 536
 537                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!!', __METHOD__, __LINE__));
 538         }
 539
 540         /**
 541          * Pre-allocates file (if enabled) with some space for later faster write access.
 542          *
 543          * @param       $type   Type of the file
 544          * @return      void
 545          */
 546         public function preAllocateFile ($type) {
 547                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 548
 549                 // Is it enabled?
 550                 if ($this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_enabled') != 'Y') {
 551                         // Not enabled
 552                         self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Not pre-allocating file.', __METHOD__, __LINE__));
 553
 554                         // Don't continue here.
 555                         return;
 556                 } // END - if
 557
 558                 // Message to user
 559                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Pre-allocating file ...', __METHOD__, __LINE__));
 560
 561                 // Calculate minimum length for one entry
 562                 $minLengthEntry = $this->getBlockInstance()->calculateMinimumBlockLength();
 563                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] minLengthEntry=%s', __METHOD__, __LINE__, $minLengthEntry));
 564
 565                 // Calulcate seek position
 566                 $seekPosition = $minLengthEntry * $this->getConfigInstance()->getConfigEntry($type . '_pre_allocate_count');
 567                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] seekPosition=%s', __METHOD__, __LINE__, $seekPosition));
 568
 569                 // Now simply write a NUL there. This will pre-allocate the file.
 570                 $this->writeData($seekPosition, chr(0));
 571
 572                 // Rewind seek position (to beginning of file) and update/flush file header
 573                 $this->rewineUpdateSeekPosition();
 574
 575                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 576         }
 577
 578         /**
 579          * Close a file source and set it's instance to null and the file name
 580          * to empty
 581          *
 582          * @return      void
 583          * @todo        ~10% done?
 584          */
 585         public function closeFile () {
 586                 $this->partialStub('Unfinished method.');
 587
 588                 // Remove file name
 589                 $this->setFileName('');
 590         }
 591
 592         /**
 593          * Determines seek position
 594          *
 595          * @return      $seekPosition   Current seek position
 596          */
 597         public function determineSeekPosition () {
 598                 // Call pointer instance
 599                 return $this->getPointerInstance()->determineSeekPosition();
 600         }
 601
 602         /**
 603          * Seek to given offset (default) or other possibilities as fseek() gives.
 604          *
 605          * @param       $offset         Offset to seek to (or used as "base" for other seeks)
 606          * @param       $whence         Added to offset (default: only use offset to seek to)
 607          * @return      $status         Status of file seek: 0 = success, -1 = failed
 608          */
 609         public function seek ($offset, $whence = SEEK_SET) {
 610                 // Call pointer instance
 611                 return $this->getPointerInstance()->seek($offset, $whence);
 612         }
 613
 614         /**
 615          * Size of this file
 616          *
 617          * @return      $size   Size (in bytes) of file
 618          * @todo        Handle seekStatus
 619          */
 620         public function size () {
 621                 // Call pointer instance
 622                 return $this->getPointerInstance()->size();
 623         }
 624
 625         /**
 626          * Read data a file pointer
 627          *
 628          * @return      mixed   The result of fread()
 629          * @throws      NullPointerException    If the file pointer instance
 630          *                                                                      is not set by setPointer()
 631          * @throws      InvalidResourceException        If there is being set
 632          */
 633         public function readFromFile () {
 634                 // Call pointer instance
 635                 return $this->getPointerInstance()->readFromFile();
 636         }
 637
 638         /**
 639          * Reads given amount of bytes from file.
 640          *
 641          * @param       $bytes  Amount of bytes to read
 642          * @return      $data   Data read from file
 643          */
 644         public function read ($bytes) {
 645                 // Call pointer instance
 646                 return $this->getPointerInstance()->read($bytes);
 647         }
 648
 649         /**
 650          * Write data to a file pointer
 651          *
 652          * @param       $dataStream             The data stream we shall write to the file
 653          * @return      mixed                   Number of writes bytes or FALSE on error
 654          * @throws      NullPointerException    If the file pointer instance
 655          *                                                                      is not set by setPointer()
 656          * @throws      InvalidResourceException        If there is being set
 657          *                                                                                      an invalid file resource
 658          */
 659         public function writeToFile ($dataStream) {
 660                 // Call pointer instance
 661                 return $this->getPointerInstance()->writeToFile($dataStream);
 662         }
 663
 664         /**
 665          * Rewinds to the beginning of the file
 666          *
 667          * @return      $status         Status of this operation
 668          */
 669         public function rewind () {
 670                 // Call pointer instance
 671                 return $this->getPointerInstance()->rewind();
 672         }
 673
 674         /**
 675          * Determines whether the EOF has been reached
 676          *
 677          * @return      $isEndOfFileReached             Whether the EOF has been reached
 678          */
 679         public final function isEndOfFileReached () {
 680                 // Call pointer instance
 681                 return $this->getPointerInstance()->isEndOfFileReached();
 682         }
 683
 684         /**
 685          * Analyzes entries in index file. This will count all found (and valid)
 686          * entries, mark invalid as damaged and count gaps ("fragmentation"). If
 687          * only gaps are found, the file is considered as "virgin" (no entries).
 688          *
 689          * @return      void
 690          */
 691         public function analyzeFile () {
 692                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] CALLED!', __METHOD__, __LINE__));
 693
 694                 // Make sure the file is initialized
 695                 assert($this->isFileInitialized());
 696
 697                 // Init counters and gaps array
 698                 $this->initCountersGapsArray();
 699
 700                 // Output message (as this may take some time)
 701                 self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] Analyzing file structure ... (this may take some time)', __METHOD__, __LINE__));
 702
 703                 // First rewind to the begining
 704                 $this->rewind();
 705
 706                 // Then try to load all entries
 707                 while ($this->valid()) {
 708                         // Go to next entry
 709                         $this->next();
 710
 711                         // Get current entry
 712                         $current = $this->getCurrentBlock();
 713
 714                         // Debug message
 715                         /* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] current()=%s', __METHOD__, __LINE__, strlen($current)));
 716                 } // END - while
 717
 718                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput(sprintf('[%s:%d:] EXIT!', __METHOD__, __LINE__));
 719         }
 720
 721         /**
 722          * Advances to next "block" of bytes
 723          *
 724          * @return      void
 725          * @todo        This method will load large but empty files in a whole
 726          */
 727         public function next () {
 728                 // Is there nothing to read?
 729                 if (!$this->valid()) {
 730                         // Nothing to read
 731                         return;
 732                 } // END - if
 733
 734                 // Make sure the block instance is set
 735                 assert($this->getBlockInstance() instanceof CalculatableBlock);
 736
 737                 // First calculate minimum block length
 738                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 739
 740                 // Short be more than zero!
 741                 assert($length > 0);
 742
 743                 // Wait until a entry/block separator has been found
 744                 $data = $this->getBackBuffer();
 745                 while ((!$this->isEndOfFileReached()) && (!self::isBlockSeparatorFound($data))) {
 746                         // Then read the block
 747                         $data .= $this->read($length);
 748                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('data()=' . strlen($data));
 749                 } // END - if
 750
 751                 // EOF reached?
 752                 if ($this->isEndOfFileReached()) {
 753                         // Set whole data as current block
 754                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('Calling setCurrentBlock(' . strlen($data) . ') ...');
 755                         $this->setCurrentBlock($data);
 756
 757                         // Then abort here silently
 758                         //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('EOF reached.');
 759                         return;
 760                 } // END - if
 761
 762                 /*
 763                  * Init back-buffer which is the data that has been found beyond the
 764                  * separator.
 765                  */
 766                 $this->initBackBuffer();
 767
 768                 // Separate data
 769                 $dataArray = explode(chr(self::SEPARATOR_ENTRIES), $data);
 770
 771                 // This array must contain two elements
 772                 //* NOISY-DEBUG: */ self::createDebugInstance(__CLASS__)->debugOutput('dataArray=' . print_r($dataArray, TRUE));
 773                 assert(count($dataArray) == 2);
 774
 775                 // Left part is the actual block, right one the back-buffer data
 776                 $this->setCurrentBlock($dataArray[0]);
 777                 $this->setBackBuffer($dataArray[1]);
 778         }
 779
 780         /**
 781          * Checks wether the current entry is valid (not at the end of the file).
 782          * This method will return TRUE if an emptied (nulled) entry has been found.
 783          *
 784          * @return      $isValid        Whether the next entry is valid
 785          */
 786         public function valid () {
 787                 // Make sure the block instance is set
 788                 assert($this->getBlockInstance() instanceof Block);
 789
 790                 // First calculate minimum block length
 791                 $length = $this->getBlockInstance()->calculateMinimumBlockLength();
 792
 793                 // Short be more than zero!
 794                 assert($length > 0);
 795
 796                 // Get current seek position
 797                 $seekPosition = $this->key();
 798
 799                 // Then try to read it
 800                 $data = $this->read($length);
 801
 802                 // If some bytes could be read, all is fine
 803                 $isValid = ((is_string($data)) && (strlen($data) > 0));
 804
 805                 // Get header size
 806                 $headerSize = $this->getBlockInstance()->getHeaderSize();
 807
 808                 // Is the seek position at or beyond the header?
 809                 if ($seekPosition >= $headerSize) {
 810                         // Seek back to old position
 811                         $this->seek($seekPosition);
 812                 } else {
 813                         // Seek directly behind the header
 814                         $this->seek($headerSize);
 815                 }
 816
 817                 // Return result
 818                 return $isValid;
 819         }
 820
 821         /**
 822          * Gets current seek position ("key").
 823          *
 824          * @return      $key    Current key in iteration
 825          */
 826         public function key () {
 827                 // Call pointer instance
 828                 return $this->getPointerInstance()->determineSeekPosition();
 829         }
 830
 831         /**
 832          * Reads the file header
 833          *
 834          * @return      void
 835          */
 836         public function readFileHeader () {
 837                 // Make sure the block instance is set
 838                 assert($this->getBlockInstance() instanceof Block);
 839
 840                 // Call block instance
 841                 $this->getBlockInstance()->readFileHeader();
 842         }
 843
 844         /**
 845          * Flushes the file header
 846          *
 847          * @return      void
 848          */
 849         public function flushFileHeader () {
 850                 // Make sure the block instance is set
 851                 assert($this->getBlockInstance() instanceof Block);
 852
 853                 // Call block instance
 854                 $this->getBlockInstance()->flushFileHeader();
 855         }
 856 }
 857
 858 // [EOF]
 859 ?>