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134 lines
3.0 KiB
PHP
Executable File
134 lines
3.0 KiB
PHP
Executable File
<?php
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/** @file limititerator.inc
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* @ingroup SPL
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* @brief class LimitIterator
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* @author Marcus Boerger
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* @date 2003 - 2009
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*
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* SPL - Standard PHP Library
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*/
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/**
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* @brief Limited Iteration over another Iterator
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* @author Marcus Boerger
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* @version 1.1
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* @since PHP 5.0
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*
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* A class that starts iteration at a certain offset and only iterates over
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* a specified amount of elements.
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*
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* This class uses SeekableIterator::seek() if available and rewind() plus
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* a skip loop otehrwise.
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*/
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class LimitIterator implements OuterIterator
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{
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private $it;
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private $offset;
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private $count;
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private $pos;
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/** Construct
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*
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* @param it Iterator to limit
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* @param offset Offset to first element
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* @param count Maximum number of elements to show or -1 for all
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*/
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function __construct(Iterator $it, $offset = 0, $count = -1)
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{
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if ($offset < 0) {
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throw new exception('Parameter offset must be > 0');
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}
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if ($count < 0 && $count != -1) {
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throw new exception('Parameter count must either be -1 or a value greater than or equal to 0');
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}
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$this->it = $it;
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$this->offset = $offset;
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$this->count = $count;
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$this->pos = 0;
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}
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/** Seek to specified position
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* @param position offset to seek to (relative to beginning not offset
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* specified in constructor).
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* @throw exception when position is invalid
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*/
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function seek($position) {
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if ($position < $this->offset) {
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throw new exception('Cannot seek to '.$position.' which is below offset '.$this->offset);
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}
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if ($position > $this->offset + $this->count && $this->count != -1) {
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throw new exception('Cannot seek to '.$position.' which is behind offset '.$this->offset.' plus count '.$this->count);
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}
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if ($this->it instanceof SeekableIterator) {
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$this->it->seek($position);
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$this->pos = $position;
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} else {
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while($this->pos < $position && $this->it->valid()) {
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$this->next();
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}
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}
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}
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/** Rewind to offset specified in constructor
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*/
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function rewind()
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{
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$this->it->rewind();
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$this->pos = 0;
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$this->seek($this->offset);
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}
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/** @return whether iterator is valid
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*/
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function valid() {
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return ($this->count == -1 || $this->pos < $this->offset + $this->count)
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&& $this->it->valid();
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}
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/** @return current key
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*/
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function key() {
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return $this->it->key();
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}
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/** @return current element
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*/
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function current() {
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return $this->it->current();
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}
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/** Forward to nect element
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*/
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function next() {
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$this->it->next();
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$this->pos++;
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}
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/** @return current position relative to zero (not to offset specified in
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* constructor).
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*/
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function getPosition() {
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return $this->pos;
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}
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/**
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* @return The inner iterator
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*/
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function getInnerIterator()
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{
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return $this->it;
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}
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/** Aggregate the inner iterator
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*
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* @param func Name of method to invoke
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* @param params Array of parameters to pass to method
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*/
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function __call($func, $params)
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{
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return call_user_func_array(array($this->it, $func), $params);
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}
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}
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?>
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