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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use dom::bindings::root::{Dom, DomRoot};
use dom::bindings::trace::JSTraceable;
use dom::globalscope::GlobalScope;
use js::jsapi::GetScriptedCallerGlobal;
use js::jsapi::HideScriptedCaller;
use js::jsapi::JSTracer;
use js::jsapi::UnhideScriptedCaller;
use js::rust::Runtime;
use std::cell::RefCell;
use std::thread;
thread_local!(static STACK: RefCell<Vec<StackEntry>> = RefCell::new(Vec::new()));
#[derive(Debug, Eq, JSTraceable, PartialEq)]
enum StackEntryKind {
Incumbent,
Entry,
}
#[allow(unrooted_must_root)]
#[derive(JSTraceable)]
struct StackEntry {
global: Dom<GlobalScope>,
kind: StackEntryKind,
}
/// Traces the script settings stack.
pub unsafe fn trace(tracer: *mut JSTracer) {
STACK.with(|stack| {
stack.borrow().trace(tracer);
})
}
pub fn is_execution_stack_empty() -> bool {
STACK.with(|stack| {
stack.borrow().is_empty()
})
}
/// RAII struct that pushes and pops entries from the script settings stack.
pub struct AutoEntryScript {
global: DomRoot<GlobalScope>,
}
impl AutoEntryScript {
/// <https://html.spec.whatwg.org/multipage/#prepare-to-run-script>
pub fn new(global: &GlobalScope) -> Self {
STACK.with(|stack| {
trace!("Prepare to run script with {:p}", global);
let mut stack = stack.borrow_mut();
stack.push(StackEntry {
global: Dom::from_ref(global),
kind: StackEntryKind::Entry,
});
AutoEntryScript {
global: DomRoot::from_ref(global),
}
})
}
}
impl Drop for AutoEntryScript {
/// <https://html.spec.whatwg.org/multipage/#clean-up-after-running-script>
fn drop(&mut self) {
STACK.with(|stack| {
let mut stack = stack.borrow_mut();
let entry = stack.pop().unwrap();
assert_eq!(&*entry.global as *const GlobalScope,
&*self.global as *const GlobalScope,
"Dropped AutoEntryScript out of order.");
assert_eq!(entry.kind, StackEntryKind::Entry);
trace!("Clean up after running script with {:p}", &*entry.global);
});
// Step 5
if !thread::panicking() && incumbent_global().is_none() {
self.global.perform_a_microtask_checkpoint();
}
}
}
/// Returns the ["entry"] global object.
///
/// ["entry"]: https://html.spec.whatwg.org/multipage/#entry
pub fn entry_global() -> DomRoot<GlobalScope> {
STACK.with(|stack| {
stack.borrow()
.iter()
.rev()
.find(|entry| entry.kind == StackEntryKind::Entry)
.map(|entry| DomRoot::from_ref(&*entry.global))
}).unwrap()
}
/// RAII struct that pushes and pops entries from the script settings stack.
pub struct AutoIncumbentScript {
global: usize,
}
impl AutoIncumbentScript {
/// <https://html.spec.whatwg.org/multipage/#prepare-to-run-a-callback>
pub fn new(global: &GlobalScope) -> Self {
// Step 2-3.
unsafe {
let cx = Runtime::get();
assert!(!cx.is_null());
HideScriptedCaller(cx);
}
STACK.with(|stack| {
trace!("Prepare to run a callback with {:p}", global);
// Step 1.
let mut stack = stack.borrow_mut();
stack.push(StackEntry {
global: Dom::from_ref(global),
kind: StackEntryKind::Incumbent,
});
AutoIncumbentScript {
global: global as *const _ as usize,
}
})
}
}
impl Drop for AutoIncumbentScript {
/// <https://html.spec.whatwg.org/multipage/#clean-up-after-running-a-callback>
fn drop(&mut self) {
STACK.with(|stack| {
// Step 4.
let mut stack = stack.borrow_mut();
let entry = stack.pop().unwrap();
// Step 3.
assert_eq!(&*entry.global as *const GlobalScope as usize,
self.global,
"Dropped AutoIncumbentScript out of order.");
assert_eq!(entry.kind, StackEntryKind::Incumbent);
trace!("Clean up after running a callback with {:p}", &*entry.global);
});
unsafe {
// Step 1-2.
let cx = Runtime::get();
assert!(!cx.is_null());
UnhideScriptedCaller(cx);
}
}
}
/// Returns the ["incumbent"] global object.
///
/// ["incumbent"]: https://html.spec.whatwg.org/multipage/#incumbent
pub fn incumbent_global() -> Option<DomRoot<GlobalScope>> {
// https://html.spec.whatwg.org/multipage/#incumbent-settings-object
// Step 1, 3: See what the JS engine has to say. If we've got a scripted
// caller override in place, the JS engine will lie to us and pretend that
// there's nothing on the JS stack, which will cause us to check the
// incumbent script stack below.
unsafe {
let cx = Runtime::get();
assert!(!cx.is_null());
let global = GetScriptedCallerGlobal(cx);
if !global.is_null() {
return Some(GlobalScope::from_object(global));
}
}
// Step 2: nothing from the JS engine. Let's use whatever's on the explicit stack.
STACK.with(|stack| {
stack.borrow()
.last()
.map(|entry| DomRoot::from_ref(&*entry.global))
})
}
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