- BC Break: _PHP_ namespaces changed (PSR-4 standard). The _root_ namespace for all _PF_ related scripts is Exodus4D\Pathfinder
- BC Break: Project folder structure changed. Removed `app/main` dir. - BC Break: Core _PHP_ framework + dependencies moved into `composer.json` and are no longer part of this repo
This commit is contained in:
Mark Friedrich
219
app/Data/File/ReverseSplFileObject.php
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219
app/Data/File/ReverseSplFileObject.php
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<?php
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/**
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* Created by PhpStorm.
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* User: Exodus 4D
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* Date: 06.08.2017
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* Time: 18:42
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*/
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namespace Exodus4D\Pathfinder\Data\File;
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class ReverseSplFileObject extends \SplFileObject{
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/**
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* pointer position indicates file start
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* @var int
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*/
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protected $begin = 0;
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/**
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* line offset from file end (1 => 'start with 2nd last line')
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* @var int
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*/
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protected $offset = 0;
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/**
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* total lines found in file
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* @var int
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*/
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protected $lineCount = 0;
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/**
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* empty lines found in file
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* @var int
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*/
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protected $lineCountEmpty = 0;
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/**
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* current pointer position
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* @var int
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*/
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protected $pointer = 0;
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/**
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* position increments when valid row data found
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* @var
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*/
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protected $position;
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/**
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* control characters
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* @var array
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*/
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protected $eol = ["\r", "\n"];
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public function __construct($sourceFile, $offset = 0){
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parent::__construct($sourceFile);
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// set total line count of the file
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$this->setLineCount();
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//Seek to the first position of the file and record its position
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//Should be 0
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$this->fseek(0);
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$this->begin = $this->ftell();
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$this->offset = $offset;
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//Seek to the last position from the end of the file
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//This varies depending on the file
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$this->fseek($this->pointer, SEEK_END);
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}
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/**
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* reverse rewind file.
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*/
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public function rewind(){
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//Set the line position to 0 - First Line
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$this->position = 0;
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//Reset the file pointer to the end of the file minus 1 character. "0" == false
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$this->fseek(-1, SEEK_END);
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$this->findLineBegin();
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//... File pointer is now at the beginning of the last line that contains data
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// add custom line offset
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if($this->offset){
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// calculate offset start line
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$offsetLine = $this->lineCount - $this->lineCountEmpty - $this->offset;
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if($offsetLine > 0){
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// row is zero based
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$offsetIndex = $offsetLine - 1;
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parent::seek($offsetIndex);
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// seek() sets pointer to next line... set it back to previous
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$this->fseek(-2, SEEK_CUR);
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$this->findLineBegin();
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//... File pointer is now at the beginning of the last line that contains data from $offset
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}else{
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// negative offsetLine -> invalid!
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$this->pointer = $this->begin -1;
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}
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}
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}
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/**
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* Return the current line after the file pointer
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* @return string
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*/
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public function current(){
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return trim($this->fgets());
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}
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/**
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* Return the current key of the line we're on
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* These go in reverse order
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* @return mixed
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*/
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public function key(){
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return $this->position;
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}
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/**
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* move one line up
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*/
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public function next(){
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//Step the file pointer back one step to the last letter of the previous line
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--$this->pointer;
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if($this->pointer < $this->begin){
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return;
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}
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$this->fseek($this->pointer);
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$this->findLineBegin();
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//File pointer is now on the next previous line
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//Increment the line position
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++$this->position;
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}
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/**
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* Check the current file pointer to make sure we are not at the beginning of the file
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* @return bool
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*/
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public function valid(){
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return ($this->pointer >= $this->begin);
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}
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/**
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* seek to previous lines
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* @param int $lineCount
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*/
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public function seek($lineCount){
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for($i = 0; $i < $lineCount; $i++){
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$this->next();
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}
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}
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/**
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* move pointer to line begin
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* -> skip line breaks
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*/
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private function findLineBegin(){
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//Check the character over and over till we hit another new line
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$c = $this->fgetc();
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// skip empty lines
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while(in_array($c, $this->eol)){
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$this->fseek(-2, SEEK_CUR);
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if(!$this->pointer = $this->ftell()){
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break;
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}
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$c = $this->fgetc();
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$this->lineCountEmpty++;
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}
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//Check the last character to make sure it is not a new line
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while(!in_array($c, $this->eol)){
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$this->fseek(-2, SEEK_CUR);
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if(!$this->pointer = $this->ftell()){
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break;
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}
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$c = $this->fgetc();
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}
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}
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/**
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* set total line count. No matter if there are empty lines in between
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*/
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private function setLineCount(){
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// Store flags and position
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$flags = $this->getFlags();
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$currentPointer = $this->ftell();
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// Prepare count by resetting flags as READ_CSV for example make the tricks very slow
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$this->setFlags(null);
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// Go to the larger INT we can as seek will not throw exception, errors, notice if we go beyond the bottom line
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//$this->seek(PHP_INT_MAX);
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parent::seek(PHP_INT_MAX);
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// We store the key position
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// As key starts at 0, we add 1
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$this->lineCount = parent::key() + 1;
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// We move to old position
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// As seek method is longer with line number < to the max line number, it is better to count at the beginning of iteration
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//parent::seek($currentPointer);
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$this->fseek($currentPointer);
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// Re set flags
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$this->setFlags($flags);
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}
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}
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