_yaml: Add 'as_bool()' and 'is_none()' to ScalarNode

- 'as_bool()' casts a ScalarNode into a boolean, understanding both
  'True' and 'False' as truthy-falsy values, as per node_get(type=bool)
  behavior
- 'is_none()' allwos checking whether the scalar node contains a 'None'
  value. Since 'None' cannot be used when working with booleans, we need
  to have a way of checking for 'None' when we actually need the
  information of whether the value is unset.
- Adapt all call places to use the new API

1 files changed, 2 insertions, 2 deletions

diff --git a/src/buildstream/_options/optionbool.py b/src/buildstream/_options/optionbool.py
index caeff9711..1e5935e48 100644
--- a/src/buildstream/_options/optionbool.py
+++ b/src/buildstream/_options/optionbool.py
@@ -34,13 +34,13 @@ class OptionBool(Option):
 
         super().load(node)
         _yaml.node_validate(node, OPTION_SYMBOLS + ['default'])
-        self.value = _yaml.node_get(node, bool, 'default')
+        self.value = node.get_bool('default')
 
     def load_value(self, node, *, transform=None):
         if transform:
             self.set_value(transform(node.get_str(self.name)))
         else:
-            self.value = _yaml.node_get(node, bool, self.name)
+            self.value = node.get_bool(self.name)
 
     def set_value(self, value):
         if value in ('True', 'true'):