From 9414d492612e08f7fa8ae46131d882547afb49ff Mon Sep 17 00:00:00 2001
From: Andrey Andreev <narf@devilix.net>
Date: Thu, 22 Jun 2017 15:39:05 +0300
Subject: Close #4134: Allow dots in alias names detected by QB

---
 system/database/DB_driver.php                      | 23 ++++++++++++----------
 user_guide_src/source/changelog.rst                |  1 +
 .../source/database/db_driver_reference.rst        |  5 +++--
 3 files changed, 17 insertions(+), 12 deletions(-)

diff --git a/system/database/DB_driver.php b/system/database/DB_driver.php
index de599a675..1dc23d72e 100644
--- a/system/database/DB_driver.php
+++ b/system/database/DB_driver.php
@@ -1320,10 +1320,11 @@ abstract class CI_DB_driver {
 	 *
 	 * This function escapes column and table names
 	 *
-	 * @param	mixed
+	 * @param	mixed	$item	Identifier to escape
+	 * @param	bool	$split	Whether to split identifiers when a dot is encountered
 	 * @return	mixed
 	 */
-	public function escape_identifiers($item)
+	public function escape_identifiers($item, $split = TRUE)
 	{
 		if ($this->_escape_char === '' OR empty($item) OR in_array($item, $this->_reserved_identifiers))
 		{
@@ -1344,22 +1345,22 @@ abstract class CI_DB_driver {
 			return $item;
 		}
 
-		static $preg_ec = array();
+		static $preg_ec;
 
 		if (empty($preg_ec))
 		{
 			if (is_array($this->_escape_char))
 			{
 				$preg_ec = array(
-					preg_quote($this->_escape_char[0], '/'),
-					preg_quote($this->_escape_char[1], '/'),
+					preg_quote($this->_escape_char[0]),
+					preg_quote($this->_escape_char[1]),
 					$this->_escape_char[0],
 					$this->_escape_char[1]
 				);
 			}
 			else
 			{
-				$preg_ec[0] = $preg_ec[1] = preg_quote($this->_escape_char, '/');
+				$preg_ec[0] = $preg_ec[1] = preg_quote($this->_escape_char);
 				$preg_ec[2] = $preg_ec[3] = $this->_escape_char;
 			}
 		}
@@ -1368,11 +1369,13 @@ abstract class CI_DB_driver {
 		{
 			if (strpos($item, '.'.$id) !== FALSE)
 			{
-				return preg_replace('/'.$preg_ec[0].'?([^'.$preg_ec[1].'\.]+)'.$preg_ec[1].'?\./i', $preg_ec[2].'$1'.$preg_ec[3].'.', $item);
+				return preg_replace('#'.$preg_ec[0].'?([^'.$preg_ec[1].'\.]+)'.$preg_ec[1].'?\.#i', $preg_ec[2].'$1'.$preg_ec[3].'.', $item);
 			}
 		}
 
-		return preg_replace('/'.$preg_ec[0].'?([^'.$preg_ec[1].'\.]+)'.$preg_ec[1].'?(\.)?/i', $preg_ec[2].'$1'.$preg_ec[3].'$2', $item);
+		$dot = ($split !== FALSE) ? '\.' : '';
+
+		return preg_replace('#'.$preg_ec[0].'?([^'.$preg_ec[1].$dot.']+)'.$preg_ec[1].'?(\.)?#i', $preg_ec[2].'$1'.$preg_ec[3].'$2', $item);
 	}
 
 	// --------------------------------------------------------------------
@@ -1786,14 +1789,14 @@ abstract class CI_DB_driver {
 		if ($offset = strripos($item, ' AS '))
 		{
 			$alias = ($protect_identifiers)
-				? substr($item, $offset, 4).$this->escape_identifiers(substr($item, $offset + 4))
+				? substr($item, $offset, 4).$this->escape_identifiers(substr($item, $offset + 4), FALSE)
 				: substr($item, $offset);
 			$item = substr($item, 0, $offset);
 		}
 		elseif ($offset = strrpos($item, ' '))
 		{
 			$alias = ($protect_identifiers)
-				? ' '.$this->escape_identifiers(substr($item, $offset + 1))
+				? ' '.$this->escape_identifiers(substr($item, $offset + 1), FALSE)
 				: substr($item, $offset);
 			$item = substr($item, 0, $offset);
 		}
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index db2be2014..c25c70e64 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -77,6 +77,7 @@ Release Date: Not Released
    -  :doc:`Query Builder <database/query_builder>`:
 
       - Added methods ``having_in()``, ``or_having_in()``, ``not_having_in()``, ``or_not_having_in()``.
+      - Updated logic to allow dots in alias names.
 
 -  Helpers
 
diff --git a/user_guide_src/source/database/db_driver_reference.rst b/user_guide_src/source/database/db_driver_reference.rst
index 6f2fa5fb1..c240526e0 100644
--- a/user_guide_src/source/database/db_driver_reference.rst
+++ b/user_guide_src/source/database/db_driver_reference.rst
@@ -305,9 +305,10 @@ This article is intended to be a reference for them.
 
 		Gets a list containing field data about a table.
 
-	.. php:method:: escape_identifiers($item)
+	.. php:method:: escape_identifiers($item, $split = TRUE)
 
 		:param	mixed	$item: The item or array of items to escape
+		:param	bool	$split: Whether to split identifiers when a dot is encountered
 		:returns:	The input item(s), escaped
 		:rtype:	mixed
 
@@ -428,4 +429,4 @@ This article is intended to be a reference for them.
 		insert the table prefix (if it exists) in the proper
 		position, and escape only the correct identifiers.
 
-		This method is used extensively by the Query Builder class.
\ No newline at end of file
+		This method is used extensively by the Query Builder class.
-- 
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