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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 https://mozilla.org/MPL/2.0/. */
//! Machinery to conditionally expose things.
use crate::dom::bindings::codegen::InterfaceObjectMap;
use crate::dom::bindings::interface::is_exposed_in;
use crate::script_runtime::JSContext;
use js::rust::HandleObject;
use servo_config::prefs;
/// A container with a condition.
pub struct Guard<T: Clone + Copy> {
condition: Condition,
value: T,
}
impl<T: Clone + Copy> Guard<T> {
/// Construct a new guarded value.
pub const fn new(condition: Condition, value: T) -> Self {
Guard {
condition: condition,
value: value,
}
}
/// Expose the value if the condition is satisfied.
///
/// The passed handle is the object on which the value may be exposed.
pub fn expose(&self, cx: JSContext, obj: HandleObject, global: HandleObject) -> Option<T> {
if self.condition.is_satisfied(cx, obj, global) {
Some(self.value)
} else {
None
}
}
}
/// A condition to expose things.
pub enum Condition {
/// The condition is satisfied if the function returns true.
Func(fn(JSContext, HandleObject) -> bool),
/// The condition is satisfied if the preference is set.
Pref(&'static str),
// The condition is satisfied if the interface is exposed in the global.
Exposed(InterfaceObjectMap::Globals),
/// The condition is always satisfied.
Satisfied,
}
impl Condition {
fn is_satisfied(&self, cx: JSContext, obj: HandleObject, global: HandleObject) -> bool {
match *self {
Condition::Pref(name) => prefs::pref_map().get(name).as_bool().unwrap_or(false),
Condition::Func(f) => f(cx, obj),
Condition::Exposed(globals) => is_exposed_in(global, globals),
Condition::Satisfied => true,
}
}
}
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