From c92ddd4cb8899b55166c8bf2ca0edd1d95783cbe Mon Sep 17 00:00:00 2001
From: Angie Byron <webchick@24967.no-reply.drupal.org>
Date: Fri, 8 Jan 2010 07:43:55 +0000
Subject: #601768 by Crell and Damien Tournoud: Add a DatabaseStatementEmpty to
 allow complex query to return a proper empty set.

---
 includes/database/database.inc | 85 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)

(limited to 'includes/database')

diff --git a/includes/database/database.inc b/includes/database/database.inc
index 916ca4cc6..98f3497ae 100644
--- a/includes/database/database.inc
+++ b/includes/database/database.inc
@@ -2004,6 +2004,91 @@ class DatabaseStatementBase extends PDOStatement implements DatabaseStatementInt
   }
 }
 
+/**
+ * Empty implementation of a database statement.
+ *
+ * This class satisfies the requirements of being a database statement/result
+ * object, but does not actually contain data.  It is useful when developers
+ * need to safely return an "empty" result set without connecting to an actual
+ * database.  Calling code can then treat it the same as if it were an actual
+ * result set that happens to contain no records.
+ *
+ * @see SearchQuery
+ */
+class DatabaseStatementEmpty implements Iterator, DatabaseStatementInterface {
+
+  public function execute($args = array(), $options = array()) {
+    return FALSE;
+  }
+
+  public function getQueryString() {
+    return '';
+  }
+
+  public function rowCount() {
+    return 0;
+  }
+
+  public function setFetchMode($mode, $a1 = NULL, $a2 = array()) {
+    return;
+  }
+
+  public function fetch($mode = NULL, $cursor_orientation = NULL, $cursor_offset = NULL) {
+    return NULL;
+  }
+
+  public function fetchField($index = 0) {
+    return NULL;
+  }
+
+  public function fetchObject() {
+    return NULL;
+  }
+
+  public function fetchAssoc() {
+    return NULL;
+  }
+
+  function fetchAll($mode = NULL, $column_index = NULL, array $constructor_arguments = array()) {
+    return array();
+  }
+
+  public function fetchCol($index = 0) {
+    return array();
+  }
+
+  public function fetchAllKeyed($key_index = 0, $value_index = 1) {
+    return array();
+  }
+
+  public function fetchAllAssoc($key, $fetch = PDO::FETCH_OBJ) {
+    return array();
+  }
+
+  /* Implementations of Iterator. */
+
+  public function current() {
+    return NULL;
+  }
+
+  public function key() {
+    return NULL;
+  }
+
+  public function rewind() {
+    // Nothing to do: our DatabaseStatement can't be rewound.
+  }
+
+  public function next() {
+    // Do nothing, since this is an always-empty implementation.
+  }
+
+  public function valid() {
+    return FALSE;
+  }
+}
+
+
 /**
  * The following utility functions are simply convenience wrappers.
  * They should never, ever have any database-specific code in them.
-- 
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