From 9c7ecb1f798f56f9b485d7cbad6e0d57805e9801 Mon Sep 17 00:00:00 2001
From: Sam Minnee <sam@silverstripe.com>
Date: Thu, 29 Jun 2017 11:17:27 +1200
Subject: [PATCH] =?UTF-8?q?Further=20work=20on=20Loz=E2=80=99=20solution?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/ORM/DataList.php          | 21 ++-----------------
 src/View/SSViewer_Scope.php   | 39 ++++++++++++++++++-----------------
 src/View/TemplateIterator.php | 24 ---------------------
 3 files changed, 22 insertions(+), 62 deletions(-)
 delete mode 100644 src/View/TemplateIterator.php

diff --git a/src/ORM/DataList.php b/src/ORM/DataList.php
index af7b73d93..2a3437847 100644
--- a/src/ORM/DataList.php
+++ b/src/ORM/DataList.php
@@ -33,7 +33,7 @@ use LogicException;
  *
  * Subclasses of DataList may add other methods that have the same effect.
  */
-class DataList extends ViewableData implements SS_List, Filterable, Sortable, Limitable, TemplateIterator
+class DataList extends ViewableData implements SS_List, Filterable, Sortable, Limitable
 {
 
     /**
@@ -883,30 +883,13 @@ class DataList extends ViewableData implements SS_List, Filterable, Sortable, Li
         }
     }
 
-    /**
-     * @return Generator|DataObject[]
-     */
-    public function getTemplateIterator()
-    {
-        foreach ($this->getFinalisedQuery() as $row) {
-            yield $this->createDataObject($row);
-        }
-    }
-
-    /**
-     * @return int
-     */
-    public function getTemplateIteratorCount()
-    {
-        return $this->getFinalisedQuery()->numRecords();
-    }
-
     /**
      * Returns the Query result for this DataList. Repeated calls will return
      * a cached result, unless the DataQuery underlying this list has been
      * modified
      *
      * @return SilverStripe\ORM\Connect\Query
+     * @internal This API may change in minor releases
      */
     protected function getFinalisedQuery()
     {
diff --git a/src/View/SSViewer_Scope.php b/src/View/SSViewer_Scope.php
index 8f7814c43..28d1b541f 100644
--- a/src/View/SSViewer_Scope.php
+++ b/src/View/SSViewer_Scope.php
@@ -290,26 +290,27 @@ class SSViewer_Scope
         }
 
         if (!$this->itemIterator) {
-            // TemplateIterator provides methods for extracting the count and iterator directly
-            if ($this->item instanceof TemplateIterator) {
-                $this->itemIterator = $this->item->getTemplateIterator();
-                $this->itemIteratorTotal = $this->item->getTemplateIteratorCount();
-            } else {
-                // Item may be an array or a regular IteratorAggregate
-                if (is_array($this->item)) {
-                    $this->itemIterator = new ArrayIterator($this->item);
-                } else {
-                    $this->itemIterator = $this->item->getIterator();
-                }
+            // Note: it is important that getIterator() is called before count() as implemenations may rely on
+            // this to efficiency get both the number of records and an iterator (e.g. DataList does this)
 
-                // If the item implements Countable, use that to fetch the count, otherwise we have to inspect the
-                // iterator and then rewind it
-                if ($this->item instanceof Countable) {
-                    $this->itemIteratorTotal = count($this->item);
-                } else {
-                    $this->itemIteratorTotal = iterator_count($this->itemIterator);
-                    $this->itemIterator->rewind();
-                }
+            // Item may be an array or a regular IteratorAggregate
+            if (is_array($this->item)) {
+                $this->itemIterator = new ArrayIterator($this->item);
+            } else {
+                $this->itemIterator = $this->item->getIterator();
+
+                // This will execute code in a generator up to the first yield. For example, this ensures that
+                // DataList::getIterator() is called before Datalist::count()
+                $this->itemIterator->rewind();
+            }
+
+            // If the item implements Countable, use that to fetch the count, otherwise we have to inspect the
+            // iterator and then rewind it.
+            if ($this->item instanceof Countable) {
+                $this->itemIteratorTotal = count($this->item);
+            } else {
+                $this->itemIteratorTotal = iterator_count($this->itemIterator);
+                $this->itemIterator->rewind();
             }
 
             $this->itemStack[$this->localIndex][SSViewer_Scope::ITEM_ITERATOR] = $this->itemIterator;
diff --git a/src/View/TemplateIterator.php b/src/View/TemplateIterator.php
deleted file mode 100644
index bc076e55b..000000000
--- a/src/View/TemplateIterator.php
+++ /dev/null
@@ -1,24 +0,0 @@
-<?php
-
-namespace SilverStripe\View;
-
-use IteratorAggregate;
-
-/**
- * A special iterator type used by the template engine. The template engine
- * needs to know the total number of items before iterating (to save rewinding
- * database queries), which is impossible with a natural Generator, so this
- * interface allows implementors to pre-compute the total number of items
- */
-interface TemplateIterator extends IteratorAggregate
-{
-    /**
-     * @return Iterator|Generator
-     */
-    public function getTemplateIterator();
-
-    /**
-     * @return int
-     */
-    public function getTemplateIteratorCount();
-}