Struct boa::builtins::object::InternalStateCell

pub struct InternalStateCell { /* fields omitted */ }

Wrapper around Rc to implement Trace and Finalize.

Implementations

impl InternalStateCell

pub fn new<T: Any + InternalState>(value: T) -> Self

Create new InternalStateCell from a value.

pub fn downcast_ref<T: Any + InternalState>(&self) -> Option<&T>

Get a reference to the stored value and cast it to T.

pub fn downcast_mut<T: Any + InternalState>(&mut self) -> Option<&mut T>

Get a mutable reference to the stored value and cast it to T.

Methods from Deref<Target = dyn Any>

pub fn is<T>(&self) -> bool where
    T: Any, 

Returns true if the boxed type is the same as T.

Examples

use std::any::Any;

fn is_string(s: &dyn Any) {
    if s.is::<String>() {
        println!("It's a string!");
    } else {
        println!("Not a string...");
    }
}

is_string(&0);
is_string(&"cookie monster".to_string());

pub fn downcast_ref<T>(&self) -> Option<&T> where
    T: Any, 

Returns some reference to the boxed value if it is of type T, or None if it isn't.

Examples

use std::any::Any;

fn print_if_string(s: &dyn Any) {
    if let Some(string) = s.downcast_ref::<String>() {
        println!("It's a string({}): '{}'", string.len(), string);
    } else {
        println!("Not a string...");
    }
}

print_if_string(&0);
print_if_string(&"cookie monster".to_string());

pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
    T: Any, 

Returns some mutable reference to the boxed value if it is of type T, or None if it isn't.

Examples

use std::any::Any;

fn modify_if_u32(s: &mut dyn Any) {
    if let Some(num) = s.downcast_mut::<u32>() {
        *num = 42;
    }
}

let mut x = 10u32;
let mut s = "starlord".to_string();

modify_if_u32(&mut x);
modify_if_u32(&mut s);

assert_eq!(x, 42);
assert_eq!(&s, "starlord");

pub fn is<T>(&self) -> bool where
    T: Any, 

Forwards to the method defined on the type Any.

Examples

use std::any::Any;

fn is_string(s: &(dyn Any + Send)) {
    if s.is::<String>() {
        println!("It's a string!");
    } else {
        println!("Not a string...");
    }
}

is_string(&0);
is_string(&"cookie monster".to_string());

pub fn downcast_ref<T>(&self) -> Option<&T> where
    T: Any, 

Forwards to the method defined on the type Any.

Examples

use std::any::Any;

fn print_if_string(s: &(dyn Any + Send)) {
    if let Some(string) = s.downcast_ref::<String>() {
        println!("It's a string({}): '{}'", string.len(), string);
    } else {
        println!("Not a string...");
    }
}

print_if_string(&0);
print_if_string(&"cookie monster".to_string());

pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
    T: Any, 

Forwards to the method defined on the type Any.

Examples

use std::any::Any;

fn modify_if_u32(s: &mut (dyn Any + Send)) {
    if let Some(num) = s.downcast_mut::<u32>() {
        *num = 42;
    }
}

let mut x = 10u32;
let mut s = "starlord".to_string();

modify_if_u32(&mut x);
modify_if_u32(&mut s);

assert_eq!(x, 42);
assert_eq!(&s, "starlord");

pub fn is<T>(&self) -> bool where
    T: Any, 

Forwards to the method defined on the type Any.

Examples

use std::any::Any;

fn is_string(s: &(dyn Any + Send + Sync)) {
    if s.is::<String>() {
        println!("It's a string!");
    } else {
        println!("Not a string...");
    }
}

is_string(&0);
is_string(&"cookie monster".to_string());

pub fn downcast_ref<T>(&self) -> Option<&T> where
    T: Any, 

Forwards to the method defined on the type Any.

Examples

use std::any::Any;

fn print_if_string(s: &(dyn Any + Send + Sync)) {
    if let Some(string) = s.downcast_ref::<String>() {
        println!("It's a string({}): '{}'", string.len(), string);
    } else {
        println!("Not a string...");
    }
}

print_if_string(&0);
print_if_string(&"cookie monster".to_string());

pub fn downcast_mut<T>(&mut self) -> Option<&mut T> where
    T: Any, 

Forwards to the method defined on the type Any.

Examples

use std::any::Any;

fn modify_if_u32(s: &mut (dyn Any + Send + Sync)) {
    if let Some(num) = s.downcast_mut::<u32>() {
        *num = 42;
    }
}

let mut x = 10u32;
let mut s = "starlord".to_string();

modify_if_u32(&mut x);
modify_if_u32(&mut s);

assert_eq!(x, 42);
assert_eq!(&s, "starlord");

Trait Implementations

impl Clone for InternalStateCell

fn clone(&self) -> InternalStateCell

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for InternalStateCell

The derived version would print 'InternalStateCell { state: ... }', this custom implementation only prints the actual internal state.

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Deref for InternalStateCell

type Target = dyn Any

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl DerefMut for InternalStateCell

fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.

impl Finalize for InternalStateCell

fn finalize(&self)

impl Trace for InternalStateCell

unsafe fn trace(&self)

Marks all contained Gcs.

unsafe fn root(&self)

Increments the root-count of all contained Gcs.

unsafe fn unroot(&self)

Decrements the root-count of all contained Gcs.

fn finalize_glue(&self)

Runs Finalize::finalize() on this object and all contained subobjects