From caf5df17aba64eb980a12f596ce98ec1f476c801 Mon Sep 17 00:00:00 2001
From: Alexandre Emsenhuber <ialex@users.mediawiki.org>
Date: Sat, 14 Jan 2012 14:27:46 +0000
Subject: [PATCH] Per Aaron, fix for r108274: added canUseWikiPage() to context
 objects to know whether getWikiPage() can be safely called

---
 includes/context/ContextSource.php     | 17 +++++++++++++++-
 includes/context/DerivativeContext.php | 23 ++++++++++++++++++++-
 includes/context/IContextSource.php    | 15 +++++++++++++-
 includes/context/RequestContext.php    | 28 +++++++++++++++++++++++++-
 4 files changed, 79 insertions(+), 4 deletions(-)

diff --git a/includes/context/ContextSource.php b/includes/context/ContextSource.php
index 2fbc776712..45bd6fffb4 100644
--- a/includes/context/ContextSource.php
+++ b/includes/context/ContextSource.php
@@ -79,7 +79,22 @@ abstract class ContextSource implements IContextSource {
 	}
 
 	/**
-	 * Get the WikiPage object
+	 * Check whether a WikiPage object can be get with getWikiPage().
+	 * Callers should expect that an exception is thrown from getWikiPage()
+	 * if this method returns false.
+	 *
+	 * @since 1.19
+	 * @return bool
+	 */
+	public function canUseWikiPage() {
+		return $this->getContext()->canUseWikiPage();
+	}
+
+	/**
+	 * Get the WikiPage object.
+	 * May throw an exception if there's no Title object set or the Title object
+	 * belongs to a special namespace that doesn't have WikiPage, so use first
+	 * canUseWikiPage() to check whether this method can be called safely.
 	 *
 	 * @since 1.19
 	 * @return WikiPage
diff --git a/includes/context/DerivativeContext.php b/includes/context/DerivativeContext.php
index ee817dbd26..5adf3621b3 100644
--- a/includes/context/DerivativeContext.php
+++ b/includes/context/DerivativeContext.php
@@ -118,6 +118,24 @@ class DerivativeContext extends ContextSource {
 		}
 	}
 
+	/**
+	 * Check whether a WikiPage object can be get with getWikiPage().
+	 * Callers should expect that an exception is thrown from getWikiPage()
+	 * if this method returns false.
+	 *
+	 * @since 1.19
+	 * @return bool
+	 */
+	public function canUseWikiPage() {
+		if ( $this->wikipage !== null ) {
+			return true;
+		} elseif ( $this->title !== null ) {
+			return $this->title->canExist();
+		} else {
+			return $this->getContext()->canUseWikiPage();
+		}
+	}
+
 	/**
 	 * Set the WikiPage object
 	 *
@@ -129,7 +147,10 @@ class DerivativeContext extends ContextSource {
 	}
 
 	/**
-	 * Get the WikiPage object
+	 * Get the WikiPage object.
+	 * May throw an exception if there's no Title object set or the Title object
+	 * belongs to a special namespace that doesn't have WikiPage, so use first
+	 * canUseWikiPage() to check whether this method can be called safely.
 	 *
 	 * @since 1.19
 	 * @return WikiPage
diff --git a/includes/context/IContextSource.php b/includes/context/IContextSource.php
index ed7aba0359..476035b525 100644
--- a/includes/context/IContextSource.php
+++ b/includes/context/IContextSource.php
@@ -43,7 +43,20 @@ interface IContextSource {
 	public function getTitle();
 
 	/**
-	 * Get the WikiPage object
+	 * Check whether a WikiPage object can be get with getWikiPage().
+	 * Callers should expect that an exception is thrown from getWikiPage()
+	 * if this method returns false.
+	 *
+	 * @since 1.19
+	 * @return bool
+	 */
+	public function canUseWikiPage();
+
+	/**
+	 * Get the WikiPage object.
+	 * May throw an exception if there's no Title object set or the Title object
+	 * belongs to a special namespace that doesn't have WikiPage, so use first
+	 * canUseWikiPage() to check whether this method can be called safely.
 	 *
 	 * @since 1.19
 	 * @return WikiPage
diff --git a/includes/context/RequestContext.php b/includes/context/RequestContext.php
index 7f000410e0..1ffbc08ce2 100644
--- a/includes/context/RequestContext.php
+++ b/includes/context/RequestContext.php
@@ -108,6 +108,29 @@ class RequestContext implements IContextSource {
 		return $this->title;
 	}
 
+	/**
+	 * Check whether a WikiPage object can be get with getWikiPage().
+	 * Callers should expect that an exception is thrown from getWikiPage()
+	 * if this method returns false.
+	 *
+	 * @since 1.19
+	 * @return bool
+	 */
+	public function canUseWikiPage() {
+		if ( $this->wikipage !== null ) {
+			# If there's a WikiPage object set, we can for sure get it
+			return true;
+		}
+		$title = $this->getTitle();
+		if ( $title === null ) {
+			# No Title, no WikiPage
+			return false;
+		} else {
+			# Only namespaces whose pages are stored in the database can have WikiPage
+			return $title->canExist();
+		}
+	}
+
 	/**
 	 * Set the WikiPage object
 	 *
@@ -119,7 +142,10 @@ class RequestContext implements IContextSource {
 	}
 
 	/**
-	 * Get the WikiPage object
+	 * Get the WikiPage object.
+	 * May throw an exception if there's no Title object set or the Title object
+	 * belongs to a special namespace that doesn't have WikiPage, so use first
+	 * canUseWikiPage() to check whether this method can be called safely.
 	 *
 	 * @since 1.19
 	 * @return WikiPage
-- 
2.20.1