From b3e36d655c831c63c26a710eb3c8bd82ca3b6fc5 Mon Sep 17 00:00:00 2001
From: Dries Buytaert <dries@buytaert.net>
Date: Sun, 22 Feb 2009 16:53:41 +0000
Subject: - Patch #299267 by Crell: add extender support to the SELECT query
 builder.

---
 includes/pager.inc | 144 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 144 insertions(+)

(limited to 'includes/pager.inc')

diff --git a/includes/pager.inc b/includes/pager.inc
index 4b219a8ca..a3c80ae5e 100644
--- a/includes/pager.inc
+++ b/includes/pager.inc
@@ -6,6 +6,150 @@
  * Functions to aid in presenting database results as a set of pages.
  */
 
+
+/**
+ * Query extender for pager queries.
+ *
+ * This is the "default" pager mechanism.  It creates a paged query with a fixed
+ * number of entries per page.
+ */
+class PagerDefault extends SelectQueryExtender {
+
+  /**
+   * The highest element we've autogenerated so far.
+   *
+   * @var int
+   */
+  static protected $maxElement = 0;
+
+  /**
+   * The number of elements per page to allow.
+   *
+   * @var int
+   */
+  protected $limit = 10;
+
+  /**
+   * The unique ID of this pager on this page.
+   *
+   * @var int
+   */
+  protected $element = NULL;
+
+  /**
+   * The count query that will be used for this pager.
+   *
+   * @var SelectQueryInterface
+   */
+  protected $customCountQuery = FALSE;
+
+  /**
+   * Override the execute method.
+   *
+   * Before we run the query, we need to add pager-based range() instructions
+   * to it.
+   */
+  public function execute() {
+    global $pager_page_array, $pager_total, $pager_total_items;
+
+    // A NULL limit is the "kill switch" for pager queries.
+    if (empty($this->limit)) {
+      return;
+    }
+    $this->ensureElement();
+
+    $page = isset($_GET['page']) ? $_GET['page'] : '';
+
+    // Convert comma-separated $page to an array, used by other functions.
+    $pager_page_array = explode(',', $page);
+
+    // We calculate the total of pages as ceil(items / limit).
+    $pager_total_items[$this->element] = $this->getCountQuery()->execute()->fetchField();
+    $pager_total[$this->element] = ceil($pager_total_items[$this->element] / $this->limit);
+    $pager_page_array[$this->element] = max(0, min((int)$pager_page_array[$this->element], ((int)$pager_total[$this->element]) - 1));
+    $this->range($pager_page_array[$this->element] * $this->limit, $this->limit);
+
+    // Now that we've added our pager-based range instructions, run the query normally.
+    return $this->query->execute();
+  }
+
+  /**
+   * Ensure that there is an element associated with this query.
+   *
+   * After running this query, access $this->element to get the element for this
+   * query.
+   */
+  protected function ensureElement() {
+    if (!empty($this->element)) {
+      return;
+    }
+
+    $this->element = self::$maxElement++;
+  }
+
+  /**
+   * Specify the count query object to use for this pager.
+   *
+   * You will rarely need to specify a count query directly.  If not specified,
+   * one is generated off of the pager query itself.
+   *
+   * @param SelectQueryInterface $query
+   *   The count query object.  It must return a single row with a single column,
+   *   which is the total number of records.
+   */
+  public function setCountQuery(SelectQueryInterface $query) {
+    $this->customCountQuery = $query;
+  }
+
+  /**
+   * Retrieve the count query for this pager.
+   *
+   * The count query may be specified manually or, by default, taken from the
+   * query we are extending.
+   *
+   * @return
+   *   A count SelectQueryInterface object.
+   */
+  protected function getCountQuery() {
+    if ($this->customCountQuery) {
+      return $this->customCountQuery;
+    }
+    else {
+      return $this->query->countQuery();
+    }
+  }
+
+  /**
+   * Specify the maximum number of elements per page for this query.
+   *
+   * The default if not specified is 10 items per page.
+   *
+   * @param $limit
+   *   An integer specifying the number of elements per page.  If passed a false
+   *   value (FALSE, 0, NULL), the pager is disabled.
+   */
+  public function limit($limit = 10) {
+    $this->limit = $limit;
+    return $this;
+  }
+
+  /**
+   * Specify the element ID for this pager query.
+   *
+   * The element is used to differentiate different pager queries on the same
+   * page so that they may be operated independently.  If you do not specify an
+   * element, every pager query on the page will get a unique element.  If for
+   * whatever reason you want to explicitly define an element for a given query,
+   * you may do so here.
+   *
+   * @param $element
+   */
+  public function element($element) {
+    $this->element = $element;
+    return $this;
+  }
+}
+
 /**
  * Perform a paged database query.
  *
-- 
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