vendor/windows/src/core/weak.rs

   1 use super::*;
   2 use imp::*;
   3 use std::marker::PhantomData;
   4
   5 /// `Weak` holds a non-owning reference to an object.
   6 #[derive(Clone, PartialEq, Eq, Default)]
   7 pub struct Weak<I: ComInterface>(Option<IWeakReference>, PhantomData<I>);
   8
   9 impl<I: ComInterface> Weak<I> {
  10     /// Creates a new `Weak` object without any backing object.
  11     pub fn new() -> Self {
  12         Self(None, PhantomData)
  13     }
  14
  15     /// Attempts to upgrade the weak reference to a strong reference.
  16     pub fn upgrade(&self) -> Option<I> {
  17         self.0.as_ref().and_then(|inner| unsafe { inner.Resolve().ok() })
  18     }
  19
  20     pub(crate) fn downgrade(source: &IWeakReferenceSource) -> Result<Self> {
  21         let reference = unsafe { source.GetWeakReference().ok() };
  22         Ok(Self(reference, PhantomData))
  23     }
  24 }