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use quote::quote_spanned;
use syn::parse_quote_spanned;
use super::{
DelayType, OperatorCategory, OperatorConstraints, OperatorWriteOutput, RANGE_0, RANGE_1,
WriteContextArgs,
};
/// > 1 input stream, 1 output stream
///
/// A specialized operator for merging lattices together into an accumulated value. Like [`reduce()`](#reduce)
/// but specialized for lattice types. `lattice_reduce()` is equivalent to `reduce(dfir_rs::lattices::Merge::merge)`.
///
/// `lattice_reduce` can also be provided with one generic lifetime persistence argument, either
/// `'tick` or `'static`, to specify how data persists. With `'tick`, values will only be collected
/// within the same tick. With `'static`, values will be remembered across ticks and will be
/// aggregated with pairs arriving in later ticks. When not explicitly specified persistence
/// defaults to `'tick`.
///
/// `lattice_reduce` is differentiated from `lattice_fold` in that `lattice_reduce` does not require the accumulating type to have a sensible default value.
/// But it also means that the accumulating function inputs and the accumulating type must be the same.
///
/// ```dfir
/// use dfir_rs::lattices::Max;
///
/// source_iter([1, 2, 3, 4, 5])
/// -> map(Max::new)
/// -> lattice_reduce()
/// -> assert_eq([Max::new(5)]);
/// ```
pub const LATTICE_REDUCE: OperatorConstraints = OperatorConstraints {
name: "lattice_reduce",
categories: &[OperatorCategory::LatticeFold],
hard_range_inn: RANGE_1,
soft_range_inn: RANGE_1,
hard_range_out: RANGE_1,
soft_range_out: RANGE_1,
num_args: 0,
persistence_args: &(0..=1),
type_args: RANGE_0,
is_external_input: false,
has_singleton_output: false,
flo_type: None,
ports_inn: None,
ports_out: None,
input_delaytype_fn: |_| Some(DelayType::MonotoneAccum),
write_fn: |wc @ &WriteContextArgs {
root,
inputs,
op_span,
is_pull,
..
},
diagnostics| {
assert!(is_pull);
let arguments = &parse_quote_spanned! {op_span=>
|acc, item| { #root::lattices::Merge::<_>::merge(acc, item); }
};
let wc = WriteContextArgs {
arguments,
..wc.clone()
};
let OperatorWriteOutput {
write_prologue,
write_prologue_after,
write_iterator,
write_iterator_after,
} = (super::reduce::REDUCE.write_fn)(&wc, diagnostics)?;
assert_eq!(1, inputs.len());
let input = &inputs[0];
let write_iterator = quote_spanned! {op_span=>
let #input = {
#[inline(always)]
fn check_inputs<Lat, Prev>(
input: Prev,
) -> impl #root::dfir_pipes::pull::Pull<Item = Lat, Meta = Prev::Meta, CanPend = Prev::CanPend, CanEnd = Prev::CanEnd>
where
Lat: #root::lattices::Merge<Lat>,
Prev: #root::dfir_pipes::pull::Pull<Item = Lat>,
{
input
}
check_inputs(#input)
};
#write_iterator
};
Ok(OperatorWriteOutput {
write_prologue,
write_prologue_after,
write_iterator,
write_iterator_after,
})
},
};