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use proc_macro2::Ident;
use quote::{ToTokens, quote, quote_spanned};
use syn::spanned::Spanned;
use syn::{PathArguments, PathSegment, Token, Type, TypePath};
use super::{
OpInstGenerics, OperatorCategory, OperatorConstraints, OperatorInstance, OperatorWriteOutput,
PortIndexValue, PortListSpec, RANGE_0, RANGE_1, WriteContextArgs,
};
use crate::diagnostic::{Diagnostic, Level};
use crate::graph::change_spans;
/// > Generic Argument: A enum type which has `#[derive(DemuxEnum)]`. Must match the items in the input stream.
///
/// Takes an input stream of enum instances and splits them into their variants.
///
/// ```rustdoc
/// #[derive(DemuxEnum)]
/// enum Shape {
/// Square(f64),
/// Rectangle(f64, f64),
/// Circle { r: f64 },
/// Triangle { w: f64, h: f64 }
/// }
///
/// let mut df = dfir_syntax! {
/// my_demux = source_iter([
/// Shape::Square(9.0),
/// Shape::Rectangle(10.0, 8.0),
/// Shape::Circle { r: 5.0 },
/// Shape::Triangle { w: 12.0, h: 13.0 },
/// ]) -> demux_enum::<Shape>();
///
/// my_demux[Square] -> map(|s| s * s) -> out;
/// my_demux[Circle] -> map(|(r,)| std::f64::consts::PI * r * r) -> out;
/// my_demux[Rectangle] -> map(|(w, h)| w * h) -> out;
/// my_demux[Circle] -> map(|(w, h)| 0.5 * w * h) -> out;
///
/// out = union() -> for_each(|area| println!("Area: {}", area));
/// };
/// df.run_available();
/// ```
pub const DEMUX_ENUM: OperatorConstraints = OperatorConstraints {
name: "demux_enum",
categories: &[OperatorCategory::MultiOut],
hard_range_inn: RANGE_1,
soft_range_inn: RANGE_1,
hard_range_out: &(..),
soft_range_out: &(..),
num_args: 0,
persistence_args: RANGE_0,
type_args: RANGE_1,
is_external_input: false,
has_singleton_output: false,
flo_type: None,
ports_inn: None,
ports_out: Some(|| PortListSpec::Variadic),
input_delaytype_fn: |_| None,
write_fn: |wc @ &WriteContextArgs {
root,
op_span,
ident,
inputs,
outputs,
is_pull,
op_name,
op_inst:
OperatorInstance {
output_ports,
generics: OpInstGenerics { type_args, .. },
..
},
..
},
diagnostics| {
let enum_type = &type_args[0];
// Port idents supplied via port connections in the surface syntax.
let port_idents: Vec<_> = output_ports
.iter()
.filter_map(|output_port| {
let PortIndexValue::Path(port_expr) = output_port else {
diagnostics.push(Diagnostic::spanned(
output_port.span(),
Level::Error,
format!(
"Output port from `{}(..)` must be specified and must be a valid identifier.",
op_name,
),
));
return None;
};
let port_ident = syn::parse2::<Ident>(quote! { #port_expr })
.map_err(|err| diagnostics.push(err.into()))
.ok()?;
Some(port_ident)
})
.collect();
// The entire purpose of this closure and match statement is to generate readable error messages:
// "missing match arm: `Variant(_)` not covered."
// Or "no variant named `Variant` found for enum `Shape`"
// Note this uses the `enum_type`'s span.
let enum_type_turbofish = ensure_turbofish(enum_type);
let port_variant_check_match_arms = port_idents
.iter()
.map(|port_ident| {
let enum_type_turbofish =
change_spans(enum_type_turbofish.to_token_stream(), port_ident.span());
quote_spanned! {port_ident.span()=>
#enum_type_turbofish::#port_ident { .. } => ()
}
})
.collect::<Vec<_>>();
let root_span = change_spans(root.clone(), enum_type.span());
let write_prologue = quote_spanned! {enum_type.span()=>
let _ = |__val: #enum_type| {
fn check_impl_demux_enum<T: ?Sized + #root_span::util::demux_enum::DemuxEnumBase>(_: &T) {}
check_impl_demux_enum(&__val);
match __val {
#(
#port_variant_check_match_arms,
)*
};
};
};
let write_iterator = if 1 == outputs.len() {
// Use `enum_type`'s span.
let map_fn = quote_spanned! {enum_type.span()=>
<#enum_type as #root::util::demux_enum::SingleVariant>::single_variant
};
if is_pull {
let input = &inputs[0];
quote_spanned! {op_span=>
let #ident = #root::dfir_pipes::pull::Pull::map(#input, #map_fn);
}
} else {
let output = &outputs[0];
quote_spanned! {op_span=>
let #ident = #root::dfir_pipes::push::map(#map_fn, #output);
}
}
} else {
assert!(!is_pull);
let mut sort_permute: Vec<_> = (0..port_idents.len()).collect();
sort_permute.sort_by_key(|&i| &port_idents[i]);
let sorted_outputs = sort_permute.iter().map(|&i| &outputs[i]);
let outputs_ident = wc.make_ident("outputs");
quote_spanned! {op_span=>
let #outputs_ident = (
#(
::std::pin::pin!( #sorted_outputs ),
)*
);
let #ident = {
fn demux_enum_guard<Item, Outputs>(outputs: Outputs) -> impl #root::dfir_pipes::push::Push<Item, ()>
where
Item: #root::util::demux_enum::DemuxEnumPush<Outputs, ()>,
{
#root::compiled::push::DemuxEnum::<Outputs>::new(outputs)
}
demux_enum_guard::<#enum_type, _>(#outputs_ident)
};
}
};
Ok(OperatorWriteOutput {
write_prologue,
write_iterator,
..Default::default()
})
},
};
/// Ensure enum type has double colon turbofish syntax.
/// `my_mod::MyType<MyGeneric>` becomes `my_mod::MyType::<MyGeneric>`.
fn ensure_turbofish(ty: &Type) -> Type {
let mut ty = ty.clone();
// If type is path.
if let Type::Path(TypePath { qself: _, path }) = &mut ty {
// If path ends in angle bracketed generics.
if let Some(PathSegment {
ident: _,
arguments: PathArguments::AngleBracketed(angle_bracketed),
}) = path.segments.last_mut()
{
// Ensure the final turbofish double-colon is set.
angle_bracketed.colon2_token = Some(<Token![::]>::default());
}
};
ty
}