[beast: 4/9] BSE: Item: add push_property_undo()

[Tim Janik <timj src gnome org>]

commit 8c510228c4e34a3f17cb319d5b4f5ec7cca19e2b
Author: Tim Janik <timj gnu org>
Date:   Thu Nov 19 13:22:49 2015 +0100

    BSE: Item: add push_property_undo()
    
    Signed-off-by: Tim Janik <timj gnu org>

 bse/bseitem.cc |   19 +++++++++++++++++++
 bse/bseitem.hh |    2 ++
 2 files changed, 21 insertions(+), 0 deletions(-)
---
diff --git a/bse/bseitem.cc b/bse/bseitem.cc
index 2a17de5..70ec79d 100644
--- a/bse/bseitem.cc
+++ b/bse/bseitem.cc
@@ -1330,6 +1330,25 @@ ItemImpl::push_item_undo (const String &blurb, const UndoLambda &lambda)
   bse_item_undo_close (ustack);
 }
 
+void
+ItemImpl::push_property_undo (const String &property_name)
+{
+  assert_return (property_name.empty() == false);
+  Any saved_value = __aida_get__ (property_name);
+  if (saved_value.empty())
+    critical ("%s: invalid property name: %s", __func__, property_name);
+  else
+    {
+      auto lambda = [property_name, saved_value] (ItemImpl &self, BseUndoStack *ustack) -> ErrorType {
+        const bool success = self.__aida_set__ (property_name, saved_value);
+        if (!success)
+          critical ("%s: failed to undo property change for '%s': %s", __func__, property_name, 
saved_value.repr());
+        return ERROR_NONE;
+      };
+      push_undo (__func__, *this, lambda);
+    }
+}
+
 ItemIfaceP
 ItemImpl::common_ancestor (ItemIface &other)
 {
diff --git a/bse/bseitem.hh b/bse/bseitem.hh
index 98c934b..65414da 100644
--- a/bse/bseitem.hh
+++ b/bse/bseitem.hh
@@ -168,6 +168,8 @@ public:
   virtual ItemIfaceP common_ancestor (ItemIface &other) override;
   virtual Icon       icon            () const override;
   virtual void       icon            (const Icon&) override;
+  /// Save the value of @a property_name onto the undo stack.
+  void               push_property_undo (const String &property_name);
   /// Push an undo @a function onto the undo stack, the @a self argument to @a function must match @a this.
   template<typename ItemT, typename... FuncArgs, typename... CallArgs> void
   push_undo (const String &blurb, ItemT &self, ErrorType (ItemT::*function) (FuncArgs...), CallArgs... args)