[gnome-builder/wip/chergert/layout] plugins: add helper to get extension by plugin_info

[Christian Hergert <chergert src gnome org>]

commit 55fc0b5c38d2fc09fbe41a3cd11e2e5c64ac9cb7
Author: Christian Hergert <chergert redhat com>
Date:   Fri Jul 14 15:42:34 2017 -0700

    plugins: add helper to get extension by plugin_info
    
    This is convenient in PeasExtensionSet, and so our adapter
    helper should have it too.

 libide/plugins/ide-extension-set-adapter.c |   43 ++++++++++++++++++++++++++++
 libide/plugins/ide-extension-set-adapter.h |    2 +
 2 files changed, 45 insertions(+), 0 deletions(-)
---
diff --git a/libide/plugins/ide-extension-set-adapter.c b/libide/plugins/ide-extension-set-adapter.c
index afc3811..7a30843 100644
--- a/libide/plugins/ide-extension-set-adapter.c
+++ b/libide/plugins/ide-extension-set-adapter.c
@@ -550,3 +550,46 @@ ide_extension_set_adapter_new (IdeContext  *context,
                        "value", value,
                        NULL);
 }
+
+static void
+locate_extension_by_plugin_info (IdeExtensionSetAdapter *self,
+                                 PeasPluginInfo         *plugin_info,
+                                 PeasExtension          *exten,
+                                 gpointer                user_data)
+{
+  struct {
+    PeasPluginInfo *plugin_info;
+    PeasExtension  *exten;
+  } *lookup = user_data;
+
+  if (lookup->plugin_info == plugin_info)
+    lookup->exten = exten;
+}
+
+/**
+ * ide_extension_set_adapter_get_extension:
+ * @self: a #IdeExtensionSetAdapter
+ * @plugin_info: a #PeasPluginInfo
+ *
+ * Locates the extension owned by @plugin_info if such extension exists.
+ *
+ * Returns: (transfer none) (nullable): A #PeasExtension or %NULL
+ */
+PeasExtension *
+ide_extension_set_adapter_get_extension (IdeExtensionSetAdapter *self,
+                                         PeasPluginInfo         *plugin_info)
+{
+  struct {
+    PeasPluginInfo *plugin_info;
+    PeasExtension  *exten;
+  } lookup = { 0 };
+
+  g_return_val_if_fail (IDE_IS_EXTENSION_SET_ADAPTER (self), NULL);
+  g_return_val_if_fail (plugin_info != NULL, NULL);
+
+  ide_extension_set_adapter_foreach (self,
+                                     locate_extension_by_plugin_info,
+                                     &lookup);
+
+  return lookup.exten;
+}
diff --git a/libide/plugins/ide-extension-set-adapter.h b/libide/plugins/ide-extension-set-adapter.h
index 27ace5f..13a3ec4 100644
--- a/libide/plugins/ide-extension-set-adapter.h
+++ b/libide/plugins/ide-extension-set-adapter.h
@@ -51,6 +51,8 @@ guint                   ide_extension_set_adapter_get_n_extensions   (IdeExtensi
 void                    ide_extension_set_adapter_foreach            (IdeExtensionSetAdapter            
*self,
                                                                       IdeExtensionSetAdapterForeachFunc  
foreach_func,
                                                                       gpointer                           
user_data);
+PeasExtension          *ide_extension_set_adapter_get_extension      (IdeExtensionSetAdapter            
*self,
+                                                                      PeasPluginInfo                    
*plugin_info);
 
 G_END_DECLS