74 lines
2.6 KiB
Rust
74 lines
2.6 KiB
Rust
//! This module contains auxilary functions which one might find useful for
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//! generating implementations of host related functionality like `Externals`.
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use nan_preserving_float::{F32, F64};
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use {RuntimeValue, Trap, ValueType};
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/// A trait that represents a value that can be directly coerced to one of
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/// wasm base value types.
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pub trait IntoWasmValue {
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/// The value type into which the self type is converted.
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const VALUE_TYPE: ValueType;
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/// Perform the conversion.
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fn into_wasm_value(self) -> RuntimeValue;
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}
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macro_rules! impl_convertible_to_wasm {
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// TODO: Replace it to Kleene ? operator
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($ty:ty, $wasm_ty:ident $(, as $cast_to:ty)* ) => {
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impl IntoWasmValue for $ty {
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const VALUE_TYPE: ValueType = ValueType::$wasm_ty;
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fn into_wasm_value(self) -> RuntimeValue {
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RuntimeValue::$wasm_ty(self $( as $cast_to)*)
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}
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}
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};
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}
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impl_convertible_to_wasm!(i32, I32);
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impl_convertible_to_wasm!(u32, I32, as i32);
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impl_convertible_to_wasm!(i64, I64);
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impl_convertible_to_wasm!(u64, I64, as i64);
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impl_convertible_to_wasm!(F32, F32);
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impl_convertible_to_wasm!(F64, F64);
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/// A trait that represents a value that can be returned from a function.
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///
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/// Basically it is superset of `IntoWasmValue` types, adding the ability to return
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/// the unit value (i.e. `()`) and return a value that signals a trap.
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pub trait IntoWasmResult {
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/// The value type into which the self type is converted or `None` in case
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/// of the unit value (aka `()` aka `void`).
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const VALUE_TYPE: Option<ValueType>;
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/// Perform the conversion.
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fn into_wasm_result(self) -> Result<Option<RuntimeValue>, Trap>;
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}
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impl IntoWasmResult for () {
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const VALUE_TYPE: Option<ValueType> = None;
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fn into_wasm_result(self) -> Result<Option<RuntimeValue>, Trap> {
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Ok(None)
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}
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}
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impl<R: IntoWasmValue, E: Into<Trap>> IntoWasmResult for Result<R, E> {
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const VALUE_TYPE: Option<ValueType> = Some(R::VALUE_TYPE);
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fn into_wasm_result(self) -> Result<Option<RuntimeValue>, Trap> {
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self.map(|v| Some(v.into_wasm_value())).map_err(Into::into)
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}
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}
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impl<E: Into<Trap>> IntoWasmResult for Result<(), E> {
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const VALUE_TYPE: Option<ValueType> = None;
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fn into_wasm_result(self) -> Result<Option<RuntimeValue>, Trap> {
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self.map(|_| None).map_err(Into::into)
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}
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}
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impl<R: IntoWasmValue> IntoWasmResult for R {
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const VALUE_TYPE: Option<ValueType> = Some(R::VALUE_TYPE);
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fn into_wasm_result(self) -> Result<Option<RuntimeValue>, Trap> {
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Ok(Some(self.into_wasm_value()))
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}
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}
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