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use std::any::Any; use std::cell::{self, RefCell}; use std::fmt; use std::rc::{Rc, Weak}; pub trait HostInfo { fn finalize(&mut self) {} } trait InternalRefBase: Any { fn as_any(&self) -> &dyn Any; fn host_info(&self) -> Option<cell::RefMut<Box<dyn HostInfo>>>; fn set_host_info(&self, info: Option<Box<dyn HostInfo>>); fn ptr_eq(&self, other: &dyn InternalRefBase) -> bool; } #[derive(Clone)] pub struct InternalRef(Rc<dyn InternalRefBase>); impl InternalRef { pub fn is_ref<T: 'static>(&self) -> bool { let r = self.0.as_any(); Any::is::<HostRef<T>>(r) } pub fn get_ref<T: 'static>(&self) -> HostRef<T> { let r = self.0.as_any(); r.downcast_ref::<HostRef<T>>() .expect("reference is not T type") .clone() } } struct AnyAndHostInfo { any: Box<dyn Any>, host_info: Option<Box<dyn HostInfo>>, } impl Drop for AnyAndHostInfo { fn drop(&mut self) { if let Some(info) = &mut self.host_info { info.finalize(); } } } #[derive(Clone)] pub struct OtherRef(Rc<RefCell<AnyAndHostInfo>>); #[derive(Clone)] pub enum AnyRef { Null, Ref(InternalRef), Other(OtherRef), } impl AnyRef { pub fn new(data: Box<dyn Any>) -> Self { let info = AnyAndHostInfo { any: data, host_info: None, }; AnyRef::Other(OtherRef(Rc::new(RefCell::new(info)))) } pub fn null() -> Self { AnyRef::Null } pub fn data(&self) -> cell::Ref<Box<dyn Any>> { match self { AnyRef::Other(OtherRef(r)) => cell::Ref::map(r.borrow(), |r| &r.any), _ => panic!("expected AnyRef::Other"), } } pub fn ptr_eq(&self, other: &AnyRef) -> bool { match (self, other) { (AnyRef::Null, AnyRef::Null) => true, (AnyRef::Ref(InternalRef(ref a)), AnyRef::Ref(InternalRef(ref b))) => { a.ptr_eq(b.as_ref()) } (AnyRef::Other(OtherRef(ref a)), AnyRef::Other(OtherRef(ref b))) => Rc::ptr_eq(a, b), _ => false, } } pub fn host_info(&self) -> Option<cell::RefMut<Box<dyn HostInfo>>> { match self { AnyRef::Null => panic!("null"), AnyRef::Ref(r) => r.0.host_info(), AnyRef::Other(r) => { let info = cell::RefMut::map(r.0.borrow_mut(), |b| &mut b.host_info); if info.is_none() { return None; } Some(cell::RefMut::map(info, |info| info.as_mut().unwrap())) } } } pub fn set_host_info(&self, info: Option<Box<dyn HostInfo>>) { match self { AnyRef::Null => panic!("null"), AnyRef::Ref(r) => r.0.set_host_info(info), AnyRef::Other(r) => { r.0.borrow_mut().host_info = info; } } } } impl fmt::Debug for AnyRef { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { match self { AnyRef::Null => write!(f, "null"), AnyRef::Ref(_) => write!(f, "anyref"), AnyRef::Other(_) => write!(f, "other ref"), } } } struct ContentBox<T> { content: T, host_info: Option<Box<dyn HostInfo>>, anyref_data: Weak<dyn InternalRefBase>, } impl<T> Drop for ContentBox<T> { fn drop(&mut self) { if let Some(info) = &mut self.host_info { info.finalize(); } } } pub struct HostRef<T>(Rc<RefCell<ContentBox<T>>>); impl<T: 'static> HostRef<T> { pub fn new(item: T) -> HostRef<T> { let anyref_data: Weak<HostRef<T>> = Weak::new(); let content = ContentBox { content: item, host_info: None, anyref_data, }; HostRef(Rc::new(RefCell::new(content))) } pub fn borrow(&self) -> cell::Ref<T> { cell::Ref::map(self.0.borrow(), |b| &b.content) } pub fn borrow_mut(&self) -> cell::RefMut<T> { cell::RefMut::map(self.0.borrow_mut(), |b| &mut b.content) } pub fn ptr_eq(&self, other: &HostRef<T>) -> bool { Rc::ptr_eq(&self.0, &other.0) } pub fn anyref(&self) -> AnyRef { let r = self.0.borrow_mut().anyref_data.upgrade(); if let Some(r) = r { return AnyRef::Ref(InternalRef(r)); } let anyref_data: Rc<dyn InternalRefBase> = Rc::new(self.clone()); self.0.borrow_mut().anyref_data = Rc::downgrade(&anyref_data); AnyRef::Ref(InternalRef(anyref_data)) } } impl<T: 'static> InternalRefBase for HostRef<T> { fn ptr_eq(&self, other: &dyn InternalRefBase) -> bool { if let Some(other) = other.as_any().downcast_ref() { self.ptr_eq(other) } else { false } } fn as_any(&self) -> &dyn Any { self } fn host_info(&self) -> Option<cell::RefMut<Box<dyn HostInfo>>> { let info = cell::RefMut::map(self.0.borrow_mut(), |b| &mut b.host_info); if info.is_none() { return None; } Some(cell::RefMut::map(info, |info| info.as_mut().unwrap())) } fn set_host_info(&self, info: Option<Box<dyn HostInfo>>) { self.0.borrow_mut().host_info = info; } } impl<T> Clone for HostRef<T> { fn clone(&self) -> HostRef<T> { HostRef(self.0.clone()) } } impl<T: fmt::Debug> fmt::Debug for HostRef<T> { fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "Ref(")?; self.0.borrow().content.fmt(f)?; write!(f, ")") } }