#[repr(C)]pub struct JSVirtualMachine { /* private fields */ }
JSVirtualMachine
and objc2
only.Expand description
An instance of JSVirtualMachine represents a single JavaScript “object space” or set of execution resources. Thread safety is supported by locking the virtual machine, with concurrent JavaScript execution supported by allocating separate instances of JSVirtualMachine.
A virtual machine may need to run deferred tasks on a run loop, such as garbage collection or resolving WebAssembly compilations. By default, a virtual machine will use the run loop of the thread it was initialized on. Currently, there is no API to change a JSVirtualMachine’s run loop once it has been initialized.
See also Apple’s documentation
Implementations§
Source§impl JSVirtualMachine
impl JSVirtualMachine
Sourcepub unsafe fn addManagedReference_withOwner(
&self,
object: Option<&AnyObject>,
owner: Option<&AnyObject>,
)
pub unsafe fn addManagedReference_withOwner( &self, object: Option<&AnyObject>, owner: Option<&AnyObject>, )
Notify the JSVirtualMachine of an external object relationship.
Allows clients of JSVirtualMachine to make the JavaScript runtime aware of arbitrary external Objective-C object graphs. The runtime can then use this information to retain any JavaScript values that are referenced from somewhere in said object graph.
For correct behavior clients must make their external object graphs reachable from within the JavaScript runtime. If an Objective-C object is reachable from within the JavaScript runtime, all managed references transitively reachable from it as recorded using -addManagedReference:withOwner: will be scanned by the garbage collector.
Parameter object
: The object that the owner points to.
Parameter owner
: The object that owns the pointed to object.
Sourcepub unsafe fn removeManagedReference_withOwner(
&self,
object: Option<&AnyObject>,
owner: Option<&AnyObject>,
)
pub unsafe fn removeManagedReference_withOwner( &self, object: Option<&AnyObject>, owner: Option<&AnyObject>, )
Notify the JSVirtualMachine that a previous object relationship no longer exists.
The JavaScript runtime will continue to scan any references that were reported to it by -addManagedReference:withOwner: until those references are removed.
Parameter object
: The object that was formerly owned.
Parameter owner
: The former owner.
Methods from Deref<Target = NSObject>§
Sourcepub fn doesNotRecognizeSelector(&self, sel: Sel) -> !
pub fn doesNotRecognizeSelector(&self, sel: Sel) -> !
Handle messages the object doesn’t recognize.
See Apple’s documentation for details.
Methods from Deref<Target = AnyObject>§
Sourcepub fn class(&self) -> &'static AnyClass
pub fn class(&self) -> &'static AnyClass
Dynamically find the class of this object.
§Panics
May panic if the object is invalid (which may be the case for objects
returned from unavailable init
/new
methods).
§Example
Check that an instance of NSObject
has the precise class NSObject
.
use objc2::ClassType;
use objc2::runtime::NSObject;
let obj = NSObject::new();
assert_eq!(obj.class(), NSObject::class());
Sourcepub unsafe fn get_ivar<T>(&self, name: &str) -> &Twhere
T: Encode,
👎Deprecated: this is difficult to use correctly, use Ivar::load
instead.
pub unsafe fn get_ivar<T>(&self, name: &str) -> &Twhere
T: Encode,
Ivar::load
instead.Use Ivar::load
instead.
§Safety
The object must have an instance variable with the given name, and it
must be of type T
.
See Ivar::load_ptr
for details surrounding this.
Sourcepub fn downcast_ref<T>(&self) -> Option<&T>where
T: DowncastTarget,
pub fn downcast_ref<T>(&self) -> Option<&T>where
T: DowncastTarget,
Attempt to downcast the object to a class of type T
.
This is the reference-variant. Use Retained::downcast
if you want
to convert a retained object to another type.
§Mutable classes
Some classes have immutable and mutable variants, such as NSString
and NSMutableString
.
When some Objective-C API signature says it gives you an immutable class, it generally expects you to not mutate that, even though it may technically be mutable “under the hood”.
So using this method to convert a NSString
to a NSMutableString
,
while not unsound, is generally frowned upon unless you created the
string yourself, or the API explicitly documents the string to be
mutable.
See Apple’s documentation on mutability and on
isKindOfClass:
for more details.
§Generic classes
Objective-C generics are called “lightweight generics”, and that’s because they aren’t exposed in the runtime. This makes it impossible to safely downcast to generic collections, so this is disallowed by this method.
You can, however, safely downcast to generic collections where all the
type-parameters are AnyObject
.
§Panics
This works internally by calling isKindOfClass:
. That means that the
object must have the instance method of that name, and an exception
will be thrown (if CoreFoundation is linked) or the process will abort
if that is not the case. In the vast majority of cases, you don’t need
to worry about this, since both root objects NSObject
and
NSProxy
implement this method.
§Examples
Cast an NSString
back and forth from NSObject
.
use objc2::rc::Retained;
use objc2_foundation::{NSObject, NSString};
let obj: Retained<NSObject> = NSString::new().into_super();
let string = obj.downcast_ref::<NSString>().unwrap();
// Or with `downcast`, if we do not need the object afterwards
let string = obj.downcast::<NSString>().unwrap();
Try (and fail) to cast an NSObject
to an NSString
.
use objc2_foundation::{NSObject, NSString};
let obj = NSObject::new();
assert!(obj.downcast_ref::<NSString>().is_none());
Try to cast to an array of strings.
use objc2_foundation::{NSArray, NSObject, NSString};
let arr = NSArray::from_retained_slice(&[NSObject::new()]);
// This is invalid and doesn't type check.
let arr = arr.downcast_ref::<NSArray<NSString>>();
This fails to compile, since it would require enumerating over the array to ensure that each element is of the desired type, which is a performance pitfall.
Downcast when processing each element instead.
use objc2_foundation::{NSArray, NSObject, NSString};
let arr = NSArray::from_retained_slice(&[NSObject::new()]);
for elem in arr {
if let Some(data) = elem.downcast_ref::<NSString>() {
// handle `data`
}
}
Trait Implementations§
Source§impl AsRef<AnyObject> for JSVirtualMachine
impl AsRef<AnyObject> for JSVirtualMachine
Source§impl AsRef<JSVirtualMachine> for JSVirtualMachine
impl AsRef<JSVirtualMachine> for JSVirtualMachine
Source§impl AsRef<NSObject> for JSVirtualMachine
impl AsRef<NSObject> for JSVirtualMachine
Source§impl Borrow<AnyObject> for JSVirtualMachine
impl Borrow<AnyObject> for JSVirtualMachine
Source§impl Borrow<NSObject> for JSVirtualMachine
impl Borrow<NSObject> for JSVirtualMachine
Source§impl ClassType for JSVirtualMachine
impl ClassType for JSVirtualMachine
Source§const NAME: &'static str = "JSVirtualMachine"
const NAME: &'static str = "JSVirtualMachine"
Source§type ThreadKind = <<JSVirtualMachine as ClassType>::Super as ClassType>::ThreadKind
type ThreadKind = <<JSVirtualMachine as ClassType>::Super as ClassType>::ThreadKind
Source§impl Debug for JSVirtualMachine
impl Debug for JSVirtualMachine
Source§impl Deref for JSVirtualMachine
impl Deref for JSVirtualMachine
Source§impl Hash for JSVirtualMachine
impl Hash for JSVirtualMachine
Source§impl Message for JSVirtualMachine
impl Message for JSVirtualMachine
Source§impl NSObjectProtocol for JSVirtualMachine
impl NSObjectProtocol for JSVirtualMachine
Source§fn isEqual(&self, other: Option<&AnyObject>) -> bool
fn isEqual(&self, other: Option<&AnyObject>) -> bool
Source§fn hash(&self) -> usize
fn hash(&self) -> usize
Source§fn isKindOfClass(&self, cls: &AnyClass) -> bool
fn isKindOfClass(&self, cls: &AnyClass) -> bool
Source§fn is_kind_of<T>(&self) -> bool
fn is_kind_of<T>(&self) -> bool
isKindOfClass
directly, or cast your objects with AnyObject::downcast_ref