Struct chakracore::value::Value

pub struct Value(_);

A JavaScript value, base class for all types.

All values are tied to a specific context and should not be reused in between.

The underlying object is represented as a JsValueRef, a reference to a ChakraCore value.

This type implements the Debug trait, but it should be used carefully. It assumes there is an active context (the same context that the value was created with).

Do not get intimidated by all the conversion methods. They are very easy to grok — there are three different types:

into_*

These do not modify any data. They only check the type of the underlying value. If the value is the designated type (e.g Object), the underlying pointer is copied and returned wrapped as the specific type.

*_representation

These create a new value, by casting to a specific type using JavaScript semantics. For example; calling number_representation on an Object results in a Number(NaN). Casting a Boolean(false) using string_representation results in a String('false').

to_*

These are utility functions to easily retrieve a native representation of the internal value. The chain of actions performed is the following: into_*() -> [*_representation()] -> value(). A call to *_representation is only performed if required (i.e a string is not redundantly converted to a string).

Methods

impl Value

fn is_undefined(&self) -> bool

Returns true if this value is undefined.

fn is_null(&self) -> bool

Returns true if this value is null.

fn is_number(&self) -> bool

Returns true if this value is a Number.

fn into_number(self) -> Option<Number>

Represent the value as a Number. Does not affect the underlying value.

fn is_string(&self) -> bool

Returns true if this value is a String.

fn into_string(self) -> Option<String>

Represent the value as a String. Does not affect the underlying value.

fn is_boolean(&self) -> bool

Returns true if this value is a Boolean.

fn into_boolean(self) -> Option<Boolean>

Represent the value as a Boolean. Does not affect the underlying value.

fn is_object(&self) -> bool

Returns true if this value is an Object.

fn into_object(self) -> Option<Object>

Represent the value as an Object. Does not affect the underlying value.

fn is_external(&self) -> bool

Returns true if this value is an External.

fn into_external(self) -> Option<External>

Represent the value as an External. Does not affect the underlying value.

fn is_function(&self) -> bool

Returns true if this value is a Function.

fn into_function(self) -> Option<Function>

Represent the value as a Function. Does not affect the underlying value.

fn is_array(&self) -> bool

Returns true if this value is an Array.

fn into_array(self) -> Option<Array>

Represent the value as an Array. Does not affect the underlying value.

fn is_array_buffer(&self) -> bool

Returns true if this value is an ArrayBuffer.

fn into_array_buffer(self) -> Option<ArrayBuffer>

Represent the value as an ArrayBuffer. Does not affect the underlying value.

fn is_promise(&self) -> bool

Returns true if this value is a Promise.

fn into_promise(self) -> Option<Promise>

Represent the value as a Promise. Does not affect the underlying value.

fn to_string(&self, _guard: &ContextGuard) -> String

Converts the value to a native string, containing the value's string representation.

fn to_integer(&self, _guard: &ContextGuard) -> i32

Converts the value to a native integer, containing the value's integer representation.

fn to_double(&self, _guard: &ContextGuard) -> f64

Converts the value to a native double, containing the value's floating point representation.

fn to_bool(&self, _guard: &ContextGuard) -> bool

Converts the value to a native boolean, containing the value's bool representation.

fn to_json(&self, guard: &ContextGuard) -> Result<String>

Converts the value to a native string, containing the value's JSON representation.

fn boolean_representation(&self, _guard: &ContextGuard) -> Boolean

Creates a new boolean with this value represented as Boolean.

fn number_representation(&self, _guard: &ContextGuard) -> Number

Creates a new number with this value represented as Number.

fn object_representation(&self, _guard: &ContextGuard) -> Object

Creates a new object with this value represented as Object.

fn string_representation(&self, _guard: &ContextGuard) -> String

Creates a new string with this value represented as String.

fn get_type(&self) -> JsValueType

Returns the type of the value. This method should be used with consideration. It does not keep track of custom types, such as External. It only returns the runtime's definition of a type.

fn equals(&self, _guard: &ContextGuard, that: &Value) -> bool

Compare two values for equality (==).

fn strict_equals(&self, _guard: &ContextGuard, that: &Value) -> bool

Compare two values for strict equality (===).

impl Value

unsafe fn from_raw(value: JsRef) -> Value

Creates an instance from a raw pointer.

This is used for managing the lifetime of JSRT objects. They are tracked using reference counting; incrementing with from_raw, and decrementing with drop.

This is required to support items stored on the heap, since the JSRT runtime only observes the stack.

If used in conjunction with a Property or any Value, it is assumed a Context is active.

fn as_raw(&self) -> JsRef

Returns the underlying raw pointer.

Trait Implementations

impl From<Function> for Value

fn from(child: Function) -> Value

Performs the conversion.

impl From<Promise> for Value

fn from(child: Promise) -> Value

Performs the conversion.

impl From<Object> for Value

fn from(child: Object) -> Value

Performs the conversion.

impl From<Array> for Value

fn from(child: Array) -> Value

Performs the conversion.

impl From<ArrayBuffer> for Value

fn from(child: ArrayBuffer) -> Value

Performs the conversion.

impl From<Boolean> for Value

fn from(child: Boolean) -> Value

Performs the conversion.

impl From<Error> for Value

fn from(child: Error) -> Value

Performs the conversion.

impl From<External> for Value

fn from(child: External) -> Value

Performs the conversion.

impl From<Number> for Value

fn from(child: Number) -> Value

Performs the conversion.

impl From<String> for Value

fn from(child: String) -> Value

Performs the conversion.

impl PartialEq for Value

fn eq(&self, other: &Value) -> bool

Use carefully (prefer strict_equals), this relies on an implicitly active context.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=.

impl Debug for Value

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

Only use for debugging, it relies on an implicitly active context.

impl Clone for Value

fn clone(&self) -> Value

Duplicates a reference counted type.

The underlying pointer will be copied, and its reference count will be incremented, returned wrapped as the type.

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

Performs copy-assignment from source.

impl Drop for Value

fn drop(&mut self)

Decrements the reference counter if the object is recyclable.