Initial commit to new repo (carried over from: https://github.com/ryancramerdesign/ProcessWire/tree/devns)

wire/core/PageArrayIterator.php

@@ -0,0 +1,189 @@
+<?php namespace ProcessWire;
+
+/**
+ * PageArrayIterator for iteration of Page objects in a lazy-loaded fashion
+ * 
+ * The custom Iterator that finds real Pages in chunks (in advance, and on demand), enabling memory 
+ * safety while maintaining reasonable speeds when iterating over a large set of Pages.
+ * 
+ * Thanks to Avoine and @sforsman for this. 
+ *
+ */
+class PageArrayIterator extends Wire implements \Iterator {
+	
+	/**
+	 * Placeholder objects for pages
+	 * 
+	 * @var array
+	 * 
+	 */
+	protected $lazypages;
+
+	/**
+	 * Current buffer of real pages
+	 * 
+	 * @var array
+	 * 
+	 */
+	protected $pages;
+
+	/**
+	 * Holds the options originally given by the user for Pages::find()
+	 * 
+	 * @var array
+	 * 
+	 */ 
+	protected $options = array();
+
+	/**
+	 * Current position
+	 * 
+	 * @var int
+	 * 
+	 */
+	protected $position = 0;
+	
+	/**
+	 * Current chunk
+	 * 
+	 * @var
+	 * 
+	 */
+	protected $currentChunk;
+	
+	/**
+	 * @var int
+	 * 
+	 */
+	protected $pagesPosition = 0;
+	
+	/**
+	 * Number of pages in current chunk
+	 * 
+	 * @var int
+	 * 
+	 */
+	protected $pagesCount = 0;
+
+	/**
+	 * Determines how many pages to load in advance. 
+	 * 
+	 * Could be adjusted or suggested automatically based on memory_limit, for an example.
+	 * 
+	 * @var int
+	 * 
+	 */ 
+	protected $chunkSize = 1000;
+	
+	/**
+	 * Construct
+	 * 
+	 * @param array $lazypages
+	 * @param array $options Options provided to $pages->find()
+	 * 
+	 */
+	public function __construct(array $lazypages, array $options = []) {
+		$this->lazypages = $lazypages;
+		$this->options = $options;
+	}
+
+	/**
+	 * Retrieves the next chunk of real pages
+	 * 
+	 */
+	protected function loadChunk() {
+		
+		$this->pagesPosition = 0;
+		$start = $this->currentChunk++ * $this->chunkSize;
+
+		// If the starting position exceeds the amount of placeholder objects, we just issue an empty
+		// PageArray, which causes the loop to stop (because valid() will return false)
+		if(!isset($this->lazypages[$start])) {
+			
+			$this->pages = $this->wire('pages')->newPageArray();
+			
+		} else {
+			
+			// Check if the user gave options for the loading
+			$options = isset($this->options['loadOptions']) ? $this->options['loadOptions'] : array();
+
+			// Always disable the cache
+			$options['cache'] = false;
+
+			// Here we retrieve a chunk of Page objects and loop over them to retrieve the IDs of the Pages.
+			$lazypages = array_slice($this->lazypages, $start, $this->chunkSize);
+			$ids = array();
+			
+			foreach($lazypages as $page) {
+				// Grab the ID from the placeholder object. We are using the internal method here which does
+				// not cause the real Page to be loaded. We only need to collect the IDs to request a chunk 
+				// of real Page-objects from Pages::getById()
+				$ids[] = $page->id;
+			}
+
+			$debug = $this->wire('pages');
+			if($debug) $this->wire('pages')->debug(false);
+			$this->pages = $this->wire('pages')->getById($ids, $options);
+			if($debug) $this->wire('pages')->debug(true);
+		}
+
+		$this->pagesCount = count($this->pages);
+	}
+	
+	/**
+	 * Rewind to beginning
+	 * 
+	 */
+	public function rewind() {
+		$this->pagesPosition = 0;
+		$this->position = 0;
+		$this->currentChunk = 0;
+		$this->pagesCount = 0;
+		$this->pages = null;
+	}
+	
+	/**
+	 * Get current Page
+	 * 
+	 * @return Page
+	 * 
+	 */
+	public function current() {
+		return $this->pages[$this->pagesPosition];
+	}
+	
+	/**
+	 * Get current key/position
+	 * 
+	 * @return int
+	 * 
+	 */
+	public function key() {
+		return $this->position;
+	}
+	
+	/**
+	 * Update current position to next
+	 * 
+	 */
+	public function next() {
+		$this->pagesPosition++;
+		$this->position++;
+	}
+	
+	/**
+	 * Return whether or not there are more items after current position
+	 * 
+	 * @return bool
+	 * 
+	 */
+	public function valid() {
+		if($this->position === 0 || $this->pagesPosition >= $this->pagesCount) {
+			// If we have just been rewound or if we have reached the end of the buffer,
+			// we will load the next chunk.
+			$this->loadChunk();
+		}
+		// We have reached the end when no Pages were loaded
+		return ($this->pagesCount > 0);
+	}
+}