Enum Val 

pub enum Val {
    Bool(bool),
    S8(i8),
    U8(u8),
    S16(i16),
    U16(u16),
    S32(i32),
    U32(u32),
    S64(i64),
    U64(u64),
    Float32(f32),
    Float64(f64),
    Char(char),
    String(String),
    List(Vec<Val>),
    Record(Vec<(String, Val)>),
    Tuple(Vec<Val>),
    Variant(String, Option<Box<Val>>),
    Enum(String),
    Option(Option<Box<Val>>),
    Result(Result<Option<Box<Val>>, Option<Box<Val>>>),
    Flags(Vec<String>),
    Resource(ResourceAny),
    Future(FutureAny),
    Stream(StreamAny),
    ErrorContext(ErrorContextAny),
}

Available on crate features runtime and component-model only.

Represents possible runtime values which a component function can either consume or produce

This is a dynamic representation of possible values in the component model. Note that this is not an efficient representation but is instead intended to be a flexible and somewhat convenient representation. The most efficient representation of component model types is to use the bindgen! macro to generate native Rust types with specialized liftings and lowerings.

This type is used in conjunction with Func::call for example if the signature of a component is not statically known ahead of time.

Equality and Val

This type implements both the Rust PartialEq and Eq traits. This type additionally contains values which are not necessarily easily equated, however, such as floats (Float32 and Float64) and resources. Equality does require that two values have the same type, and then these cases are handled as:

• Floats are tested if they are “semantically the same” meaning all NaN values are equal to all other NaN values. Additionally zero values must be exactly the same, so positive zero is not equal to negative zero. The primary use case at this time is fuzzing-related equality which this is sufficient for.

• Resources are tested if their types and indices into the host table are equal. This does not compare the underlying representation so borrows of the same guest resource are not considered equal. This additionally doesn’t go further and test for equality in the guest itself (for example two different heap allocations of Box<u32> can be equal in normal Rust if they contain the same value, but will never be considered equal when compared as Val::Resources).

In general if a strict guarantee about equality is required here it’s recommended to “build your own” as this equality intended for fuzzing Wasmtime may not be suitable for you.

Component model types and Val

The Val type here does not contain enough information to say what the component model type of a Val is. This is instead more of an AST of sorts. For example the Val::Enum only carries information about a single discriminant, not the entire enumeration or what it’s a discriminant of.

This means that when a Val is passed to Wasmtime, for example as a function parameter when calling a function or as a return value from an host-defined imported function, then it must pass a type-check. Instances of Val are type-checked against what’s required by the component itself.

Variants

Bool(bool)

S8(i8)

U8(u8)

S16(i16)

U16(u16)

S32(i32)

U32(u32)

S64(i64)

U64(u64)

Float32(f32)

Float64(f64)

Char(char)

String(String)

List(Vec<Val>)

Record(Vec<(String, Val)>)

Tuple(Vec<Val>)

Variant(String, Option<Box<Val>>)

Enum(String)

Option(Option<Box<Val>>)

Result(Result<Option<Box<Val>>, Option<Box<Val>>>)

Flags(Vec<String>)

Resource(ResourceAny)

Future(FutureAny)

Stream(StreamAny)

ErrorContext(ErrorContextAny)

Implementations

impl Val

pub fn from_wave(ty: &Type, s: &str) -> Result<Self>

Available on crate feature wave only.

Deserialize a Val from its [crate::component::wasm_wave] encoding. Deserialization requires a target crate::component::Type.

pub fn to_wave(&self) -> Result<String>

Available on crate feature wave only.

Serialize a Val to its [crate::component::wasm_wave] encoding.

Trait Implementations

impl Clone for Val

fn clone(&self) -> Val

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Val

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

Formats the value using the given formatter.

impl PartialEq for Val

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl WasmValue for Val

Available on crate feature wave only.

type Type = Type

A type representing types of these values.

fn kind(&self) -> WasmTypeKind

The kind of type of this value.

fn make_bool(val: bool) -> Self

Returns a new WasmValue of the given type.

fn unwrap_bool(&self) -> bool

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_s8(val: i8) -> Self

Returns a new WasmValue of the given type.

fn unwrap_s8(&self) -> i8

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_s16(val: i16) -> Self

Returns a new WasmValue of the given type.

fn unwrap_s16(&self) -> i16

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_s32(val: i32) -> Self

Returns a new WasmValue of the given type.

fn unwrap_s32(&self) -> i32

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_s64(val: i64) -> Self

Returns a new WasmValue of the given type.

fn unwrap_s64(&self) -> i64

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_u8(val: u8) -> Self

Returns a new WasmValue of the given type.

fn unwrap_u8(&self) -> u8

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_u16(val: u16) -> Self

Returns a new WasmValue of the given type.

fn unwrap_u16(&self) -> u16

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_u32(val: u32) -> Self

Returns a new WasmValue of the given type.

fn unwrap_u32(&self) -> u32

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_u64(val: u64) -> Self

Returns a new WasmValue of the given type.

fn unwrap_u64(&self) -> u64

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_char(val: char) -> Self

Returns a new WasmValue of the given type.

fn unwrap_char(&self) -> char

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn make_f32(val: f32) -> Self

Returns a new WasmValue of the given type.

fn make_f64(val: f64) -> Self

Returns a new WasmValue of the given type.

fn make_string(val: Cow<'_, str>) -> Self

Returns a new WasmValue of the given type.

fn make_list( ty: &Self::Type, vals: impl IntoIterator<Item = Self>, ) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn make_record<'a>( ty: &Self::Type, fields: impl IntoIterator<Item = (&'a str, Self)>, ) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn make_tuple( ty: &Self::Type, vals: impl IntoIterator<Item = Self>, ) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn make_variant( ty: &Self::Type, case: &str, val: Option<Self>, ) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn make_enum(ty: &Self::Type, case: &str) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn make_option( ty: &Self::Type, val: Option<Self>, ) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn make_result( ty: &Self::Type, val: Result<Option<Self>, Option<Self>>, ) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn make_flags<'a>( ty: &Self::Type, names: impl IntoIterator<Item = &'a str>, ) -> Result<Self, WasmValueError>

Returns a new WasmValue of the given type.

fn unwrap_f32(&self) -> f32

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn unwrap_f64(&self) -> f64

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn unwrap_string(&self) -> Cow<'_, str>

Returns the underlying value of the WasmValue, panicing if it’s the wrong type.

fn unwrap_list(&self) -> Box<dyn Iterator<Item = Cow<'_, Self>> + '_>

Returns an iterator of the element Vals of the list.

fn unwrap_record( &self, ) -> Box<dyn Iterator<Item = (Cow<'_, str>, Cow<'_, Self>)> + '_>

Returns an iterator of the field names and Vals of the record.

fn unwrap_tuple(&self) -> Box<dyn Iterator<Item = Cow<'_, Self>> + '_>

Returns an iterator of the field Vals of the tuple.

fn unwrap_variant(&self) -> (Cow<'_, str>, Option<Cow<'_, Self>>)

Returns the variant case name and optional payload WasmValue of the variant.

fn unwrap_enum(&self) -> Cow<'_, str>

Returns the case name of the enum.

fn unwrap_option(&self) -> Option<Cow<'_, Self>>

Returns the optional WasmValue.

fn unwrap_result(&self) -> Result<Option<Cow<'_, Self>>, Option<Cow<'_, Self>>>

Returns Ok() or Err() with the optional payload WasmValue.

fn unwrap_flags(&self) -> Box<dyn Iterator<Item = Cow<'_, str>> + '_>

Returns an iterator of the names of the flags WasmValue.

impl Eq for Val