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/*
* Copyright 2019 The Starlark in Rust Authors.
* Copyright (c) Facebook, Inc. and its affiliates.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/// Reduce boilerplate when making types instances of [`ComplexValue`](crate::values::ComplexValue)
/// - see the [`ComplexValue`](crate::values::ComplexValue) docs for an example.
#[macro_export]
macro_rules! starlark_complex_value {
// Common part of macro variants.
(impl $x:ident) => {
$crate::__macro_refs::item! {
impl<'v> $crate::values::AllocValue<'v> for $x<'v> {
#[inline]
fn alloc_value(self, heap: &'v $crate::values::Heap) -> $crate::values::Value<'v> {
heap.alloc_complex(self)
}
}
impl $crate::values::AllocFrozenValue for [< Frozen $x >] {
#[inline]
fn alloc_frozen_value(self, heap: &$crate::values::FrozenHeap) -> $crate::values::FrozenValue {
heap.alloc_simple(self)
}
}
impl<'v> $x<'v> {
/// Downcast the value.
#[inline]
pub fn from_value(x: $crate::values::Value<'v>) -> Option<&'v Self> {
if let Some(x) = x.unpack_frozen() {
$crate::values::ValueLike::downcast_ref::< [< Frozen $x >] >(x).map($crate::__macro_refs::coerce)
} else {
$crate::values::ValueLike::downcast_ref::< $x<'v> >(x)
}
}
}
impl<'v> $crate::values::type_repr::StarlarkTypeRepr for &'v $x<'v> {
type Canonical = $x<'v>;
#[inline]
fn starlark_type_repr() -> $crate::typing::Ty {
<$x as $crate::values::StarlarkValue>::get_type_starlark_repr()
}
}
impl<'v> $crate::values::UnpackValue<'v> for &'v $x<'v> {
type Error = std::convert::Infallible;
#[inline]
fn unpack_value_impl(x: $crate::values::Value<'v>) -> Result<Option<&'v $x<'v>>, Self::Error> {
Ok($x::from_value(x))
}
}
}
};
($v:vis $x:ident) => {
$crate::__macro_refs::item! {
/// Type of value.
$v type $x<'v> = [< $x Gen >]<$crate::values::Value<'v>>;
/// Type of frozen value.
$v type [< Frozen $x >] = [< $x Gen >]<$crate::values::FrozenValue>;
starlark_complex_value!(impl $x);
}
};
($v:vis $x:ident <'v>) => {
$crate::__macro_refs::item! {
/// Type of unfrozen value.
$v type $x<'v> = [< $x Gen >]<'v, $crate::values::Value<'v>>;
/// Type of frozen value.
$v type [< Frozen $x >] = [< $x Gen >]<'static, $crate::values::FrozenValue>;
starlark_complex_value!(impl $x);
}
};
}
/// Reduce boilerplate when making types instances of [`ComplexValue`](crate::values::ComplexValue)
/// - see the [`ComplexValue`](crate::values::ComplexValue) docs for an example.
#[macro_export]
macro_rules! starlark_complex_values {
($x:ident) => {
$crate::__macro_refs::item! {
impl<'v> $crate::values::AllocValue<'v> for $x<'v> {
#[inline]
fn alloc_value(self, heap: &'v $crate::values::Heap) -> $crate::values::Value<'v> {
heap.alloc_complex(self)
}
}
impl $crate::values::AllocFrozenValue for [< Frozen $x >] {
#[inline]
fn alloc_frozen_value(self, heap: &$crate::values::FrozenHeap) -> $crate::values::FrozenValue {
heap.alloc_simple(self)
}
}
impl<'v> $x<'v> {
#[allow(dead_code)]
#[inline]
pub(crate) fn from_value(
x: $crate::values::Value<'v>,
) -> Option<$crate::__macro_refs::Either<&'v Self, &'v [< Frozen $x >]>> {
if let Some(x) = x.unpack_frozen() {
$crate::values::ValueLike::downcast_ref(x).map($crate::__macro_refs::Either::Right)
} else {
$crate::values::ValueLike::downcast_ref(x).map($crate::__macro_refs::Either::Left)
}
}
}
}
};
}
/// A macro reducing boilerplace defining Starlark values which are simple - they
/// aren't mutable and can't contain references to other Starlark values.
///
/// Let's define a simple object, where `+x` makes the string uppercase:
///
/// ```
/// use allocative::Allocative;
/// use derive_more::Display;
/// use starlark::starlark_simple_value;
/// use starlark::values::Heap;
/// use starlark::values::NoSerialize;
/// use starlark::values::ProvidesStaticType;
/// use starlark::values::StarlarkValue;
/// use starlark::values::Value;
/// use starlark_derive::starlark_value;
///
/// #[derive(Debug, Display, ProvidesStaticType, NoSerialize, Allocative)]
/// struct MyObject(String);
/// starlark_simple_value!(MyObject);
///
/// #[starlark_value(type = "my_object")]
/// impl<'v> StarlarkValue<'v> for MyObject {
/// // We can choose to implement whichever methods we want.
/// // All other operations will result in runtime errors.
/// fn plus(&self, heap: &'v Heap) -> starlark::Result<Value<'v>> {
/// Ok(heap.alloc(MyObject(self.0.to_uppercase())))
/// }
/// }
/// ```
///
/// The `starlark_simple_value!` macro defines instances of
/// [`ProvidesStaticType`](crate::values::ProvidesStaticType),
/// [`AllocValue`](crate::values::AllocValue),
/// [`AllocFrozenValue`](crate::values::AllocFrozenValue) and
/// [`UnpackValue`](crate::values::UnpackValue). It also defines a method:
///
/// ```
/// # use crate::starlark::values::*;
/// # struct MyObject;
/// impl MyObject {
/// pub fn from_value<'v>(x: Value<'v>) -> Option<&'v MyObject> {
/// # unimplemented!(
/// # r#"
/// ...
/// # "#);
/// }
/// }
/// ```
#[macro_export]
macro_rules! starlark_simple_value {
($x:ident) => {
$crate::__macro_refs::item! {
impl<'v> $crate::values::AllocValue<'v> for $x {
#[inline]
fn alloc_value(self, heap: &'v $crate::values::Heap) -> $crate::values::Value<'v> {
heap.alloc_simple(self)
}
}
impl $crate::values::AllocFrozenValue for $x {
#[inline]
fn alloc_frozen_value(self, heap: &$crate::values::FrozenHeap) -> $crate::values::FrozenValue {
heap.alloc_simple(self)
}
}
impl $x {
/// Downcast a value to self type.
#[inline]
pub fn from_value<'v>(x: $crate::values::Value<'v>) -> Option<&'v Self> {
$crate::values::ValueLike::downcast_ref::< $x >(x)
}
}
impl<'v> $crate::values::type_repr::StarlarkTypeRepr for &'v $x {
type Canonical = $x;
fn starlark_type_repr() -> $crate::typing::Ty {
<$x as $crate::values::StarlarkValue>::get_type_starlark_repr()
}
}
impl<'v> $crate::values::UnpackValue<'v> for &'v $x {
type Error = std::convert::Infallible;
#[inline]
fn unpack_value_impl(x: $crate::values::Value<'v>) -> std::result::Result<Option<&'v $x>, Self::Error> {
std::result::Result::Ok($x::from_value(x))
}
}
}
};
}