[clang.py] Add CachedProperty decorator
It isn't used anywhere yet.
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@162190 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/bindings/python/clang/cindex.py b/bindings/python/clang/cindex.py
index ee85585..d571b2a 100644
--- a/bindings/python/clang/cindex.py
+++ b/bindings/python/clang/cindex.py
@@ -133,6 +133,31 @@
### Structures and Utility Classes ###
+class CachedProperty(object):
+ """Decorator that lazy-loads the value of a property.
+
+ The first time the property is accessed, the original property function is
+ executed. The value it returns is set as the new value of that instance's
+ property, replacing the original method.
+ """
+
+ def __init__(self, wrapped):
+ self.wrapped = wrapped
+ try:
+ self.__doc__ = wrapped.__doc__
+ except:
+ pass
+
+ def __get__(self, instance, instance_type=None):
+ if instance is None:
+ return self
+
+ value = self.wrapped(instance)
+ setattr(instance, self.wrapped.__name__, value)
+
+ return value
+
+
class _CXString(Structure):
"""Helper for transforming CXString results."""
