[gnome-builder/gnome-builder-3-18] buffer: track buffer changes with sequence counter

[Christian Hergert <chergert src gnome org>]

commit 3b49a00c4239580c1473e991e98d0c301b24aa98
Author: Christian Hergert <christian hergert me>
Date:   Tue Sep 29 13:23:42 2015 -0700

    buffer: track buffer changes with sequence counter
    
    ide_buffer_get_change_count() can be used to determine if the buffer has
    been changed since the last time you looked at it. All changes, including
    undo, will increment this counter.

 libide/ide-buffer.c |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)
---
diff --git a/libide/ide-buffer.c b/libide/ide-buffer.c
index c3ab1ba..d52f0f4 100644
--- a/libide/ide-buffer.c
+++ b/libide/ide-buffer.c
@@ -84,6 +84,8 @@ typedef struct
   gint                    hold_count;
   guint                   reclamation_handler;
 
+  gsize                   change_count;
+
   guint                   changed_on_volume : 1;
   guint                   diagnostics_dirty : 1;
   guint                   highlight_diagnostics : 1;
@@ -646,6 +648,7 @@ ide_buffer_changed (GtkTextBuffer *buffer)
 
   GTK_TEXT_BUFFER_CLASS (ide_buffer_parent_class)->changed (buffer);
 
+  priv->change_count++;
   priv->diagnostics_dirty = TRUE;
 
   g_clear_pointer (&priv->content, g_bytes_unref);
@@ -2193,3 +2196,13 @@ ide_buffer_get_word_at_iter (IdeBuffer         *self,
 
   return gtk_text_iter_get_slice (&begin, &end);
 }
+
+gsize
+ide_buffer_get_change_count (IdeBuffer *self)
+{
+  IdeBufferPrivate *priv = ide_buffer_get_instance_private (self);
+
+  g_return_val_if_fail (IDE_IS_BUFFER (self), 0);
+
+  return priv->change_count;
+}