[gtksourceview] Explicit check if highlight engine is set for context_class API

[Jesse van den Kieboom <jessevdk src gnome org>]

commit 026949077e9f87323b66f60ece7392b6c4b8bc8d
Author: Jesse van den Kieboom <jesse vandenkieboom epfl ch>
Date:   Sat Jan 2 16:16:14 2010 +0100

    Explicit check if highlight engine is set for context_class API

 gtksourceview/gtksourcebuffer.c |   15 +++++++++++++++
 1 files changed, 15 insertions(+), 0 deletions(-)
---
diff --git a/gtksourceview/gtksourcebuffer.c b/gtksourceview/gtksourcebuffer.c
index 9a197d2..9826efe 100644
--- a/gtksourceview/gtksourcebuffer.c
+++ b/gtksourceview/gtksourcebuffer.c
@@ -2027,6 +2027,11 @@ gtk_source_buffer_iter_has_context_class (GtkSourceBuffer   *buffer,
 	g_return_val_if_fail (iter != NULL, FALSE);
 	g_return_val_if_fail (context_class != NULL, FALSE);
 
+	if (buffer->priv->highlight_engine == NULL)
+	{
+		return FALSE;
+	}
+
 	tag = _gtk_source_engine_get_context_class_tag (buffer->priv->highlight_engine,
 							context_class);
 
@@ -2108,6 +2113,11 @@ gtk_source_buffer_iter_forward_to_context_class_toggle (GtkSourceBuffer *buffer,
 	g_return_val_if_fail (iter != NULL, FALSE);
 	g_return_val_if_fail (context_class != NULL, FALSE);
 
+	if (buffer->priv->highlight_engine == NULL)
+	{
+		return FALSE;
+	}
+
 	tag = _gtk_source_engine_get_context_class_tag (buffer->priv->highlight_engine,
 							context_class);
 
@@ -2148,6 +2158,11 @@ gtk_source_buffer_iter_backward_to_context_class_toggle (GtkSourceBuffer *buffer
 	g_return_val_if_fail (iter != NULL, FALSE);
 	g_return_val_if_fail (context_class != NULL, FALSE);
 
+	if (buffer->priv->highlight_engine == NULL)
+	{
+		return FALSE;
+	}
+
 	tag = _gtk_source_engine_get_context_class_tag (buffer->priv->highlight_engine,
 							context_class);