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use std::mem::transmute;
use std::ptr::NonNull;
use crate::InIsolate;
use crate::Isolate;
use crate::Local;
use crate::ToLocal;
use crate::Value;
extern "C" {
fn v8__Local__New(isolate: *mut Isolate, other: *mut Value) -> *mut Value;
fn v8__Global__New(isolate: *mut Isolate, other: *mut Value) -> *mut Value;
fn v8__Global__Reset__0(this: &mut *mut Value);
fn v8__Global__Reset__2(
this: &mut *mut Value,
isolate: *mut Isolate,
other: &*mut Value,
);
}
#[repr(C)]
pub struct Global<T> {
value: Option<NonNull<T>>,
isolate: Option<NonNull<Isolate>>,
}
unsafe impl<T> Send for Global<T> {}
impl<T> Global<T> {
pub fn new() -> Self {
Self {
value: None,
isolate: None,
}
}
pub fn new_from(
scope: &mut impl InIsolate,
other: impl AnyHandle<T>,
) -> Self {
let isolate = scope.isolate();
let other_value = other.read(isolate);
Self {
value: other_value
.map(|v| unsafe { transmute(v8__Global__New(isolate, transmute(v))) }),
isolate: other_value.map(|_| isolate.into()),
}
}
pub fn is_empty(&self) -> bool {
self.value.is_none()
}
pub fn get<'sc>(
&self,
scope: &mut impl ToLocal<'sc>,
) -> Option<Local<'sc, T>> {
self.check_isolate(scope.isolate());
match &self.value {
None => None,
Some(p) => unsafe { scope.to_local(p.as_ptr()) },
}
}
pub fn set(&mut self, scope: &mut impl InIsolate, other: impl AnyHandle<T>) {
let isolate = scope.isolate();
self.check_isolate(isolate);
let other_value = other.read(isolate);
match (&mut self.value, &other_value) {
(None, None) => {}
(target, None) => unsafe {
v8__Global__Reset__0(
&mut *(target as *mut Option<NonNull<T>> as *mut *mut Value),
)
},
(target, source) => unsafe {
v8__Global__Reset__2(
&mut *(target as *mut Option<NonNull<T>> as *mut *mut Value),
isolate,
&*(source as *const Option<NonNull<T>> as *const *mut Value),
)
},
}
self.isolate = other_value.map(|_| isolate.into());
}
pub fn reset(&mut self, scope: &mut impl InIsolate) {
self.set(scope, None);
}
fn check_isolate(&self, other: &Isolate) {
match self.value {
None => assert_eq!(self.isolate, None),
Some(_) => assert_eq!(self.isolate.unwrap(), other.into()),
}
}
}
impl<T> Default for Global<T> {
fn default() -> Self {
Self::new()
}
}
impl<T> Drop for Global<T> {
fn drop(&mut self) {
if !self.is_empty() {
panic!("Global handle dropped while holding a value");
}
}
}
pub trait AnyHandle<T> {
fn read(self, isolate: &Isolate) -> Option<NonNull<T>>;
}
impl<'sc, T> AnyHandle<T> for Local<'sc, T> {
fn read(self, _isolate: &Isolate) -> Option<NonNull<T>> {
Some(self.as_non_null())
}
}
impl<'sc, T> AnyHandle<T> for Option<Local<'sc, T>> {
fn read(self, _isolate: &Isolate) -> Option<NonNull<T>> {
self.map(|local| local.as_non_null())
}
}
impl<'sc, T> AnyHandle<T> for &Global<T> {
fn read(self, isolate: &Isolate) -> Option<NonNull<T>> {
self.check_isolate(isolate);
self.value
}
}