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dfir_lang/graph/ops/
mod.rs

1//! DFIR's operators
2
3use std::collections::HashMap;
4use std::fmt::{Debug, Display};
5use std::ops::{Bound, RangeBounds};
6use std::sync::OnceLock;
7
8use documented::DocumentedVariants;
9use proc_macro2::{Ident, Literal, Span, TokenStream};
10use quote::quote_spanned;
11use serde::{Deserialize, Serialize};
12use slotmap::Key;
13use syn::punctuated::Punctuated;
14use syn::{Expr, Token, parse_quote_spanned};
15
16use super::{
17    GraphLoopId, GraphNode, GraphNodeId, GraphSubgraphId, OpInstGenerics, OperatorInstance,
18    PortIndexValue,
19};
20use crate::diagnostic::{Diagnostic, Diagnostics, Level};
21use crate::parse::{Operator, PortIndex};
22
23/// The delay (soft barrier) type, for each input to an operator if needed.
24#[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Debug, Serialize, Deserialize)]
25pub enum DelayType {
26    /// Input must be collected over the preceding stratum.
27    Stratum,
28    /// Monotone accumulation: can delay to reduce flow rate, but also correct to emit "early"
29    MonotoneAccum,
30    /// Input must be collected over the previous tick.
31    Tick,
32    /// Input must be collected over the previous tick but also not cause a new tick to occur.
33    TickLazy,
34}
35
36/// Specification of the named (or unnamed) ports for an operator's inputs or outputs.
37pub enum PortListSpec {
38    /// Any number of unnamed (or optionally named) ports.
39    Variadic,
40    /// A specific number of named ports.
41    Fixed(Punctuated<PortIndex, Token![,]>),
42}
43
44/// An instance of this struct represents a single dfir operator.
45pub struct OperatorConstraints {
46    /// Operator's name.
47    pub name: &'static str,
48    /// Operator categories, for docs.
49    pub categories: &'static [OperatorCategory],
50
51    // TODO: generic argument ranges.
52    /// Input argument range required to not show an error.
53    pub hard_range_inn: &'static dyn RangeTrait<usize>,
54    /// Input argument range required to not show a warning.
55    pub soft_range_inn: &'static dyn RangeTrait<usize>,
56    /// Output argument range required to not show an error.
57    pub hard_range_out: &'static dyn RangeTrait<usize>,
58    /// Output argument range required to not show an warning.
59    pub soft_range_out: &'static dyn RangeTrait<usize>,
60    /// Number of arguments i.e. `operator(a, b, c)` has `num_args = 3`.
61    pub num_args: usize,
62    /// How many persistence lifetime arguments can be provided.
63    pub persistence_args: &'static dyn RangeTrait<usize>,
64    // /// How many (non-persistence) lifetime arguments can be provided.
65    // pub lifetime_args: &'static dyn RangeTrait<usize>,
66    /// How many generic type arguments can be provided.
67    pub type_args: &'static dyn RangeTrait<usize>,
68    /// If this operator receives external inputs and therefore must be in
69    /// stratum 0.
70    pub is_external_input: bool,
71    /// If this operator has a singleton reference output. For stateful operators.
72    /// If true, [`WriteContextArgs::singleton_output_ident`] will be set to a meaningful value in
73    /// the [`Self::write_fn`] invocation.
74    pub has_singleton_output: bool,
75    /// Flo semantics type.
76    pub flo_type: Option<FloType>,
77
78    /// What named or numbered input ports to expect?
79    pub ports_inn: Option<fn() -> PortListSpec>,
80    /// What named or numbered output ports to expect?
81    pub ports_out: Option<fn() -> PortListSpec>,
82
83    /// Determines if this input must be preceeded by a stratum barrier.
84    pub input_delaytype_fn: fn(&PortIndexValue) -> Option<DelayType>,
85    /// The operator's codegen. Returns code that is emited is several different locations. See [`OperatorWriteOutput`].
86    pub write_fn: WriteFn,
87}
88
89/// Type alias for [`OperatorConstraints::write_fn`]'s type.
90pub type WriteFn = fn(&WriteContextArgs<'_>, &mut Diagnostics) -> Result<OperatorWriteOutput, ()>;
91
92impl Debug for OperatorConstraints {
93    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
94        f.debug_struct("OperatorConstraints")
95            .field("name", &self.name)
96            .field("hard_range_inn", &self.hard_range_inn)
97            .field("soft_range_inn", &self.soft_range_inn)
98            .field("hard_range_out", &self.hard_range_out)
99            .field("soft_range_out", &self.soft_range_out)
100            .field("num_args", &self.num_args)
101            .field("persistence_args", &self.persistence_args)
102            .field("type_args", &self.type_args)
103            .field("is_external_input", &self.is_external_input)
104            .field("ports_inn", &self.ports_inn)
105            .field("ports_out", &self.ports_out)
106            // .field("input_delaytype_fn", &self.input_delaytype_fn)
107            // .field("flow_prop_fn", &self.flow_prop_fn)
108            // .field("write_fn", &self.write_fn)
109            .finish()
110    }
111}
112
113/// The code generated and returned by a [`OperatorConstraints::write_fn`].
114/// **Important**: When destructuring this struct in delegating operators, list all fields
115/// explicitly rather than using `..` to ensure new fields are not silently dropped.
116#[derive(Default)]
117pub struct OperatorWriteOutput {
118    /// Code which runs once outside any subgraphs to set up external state
119    /// (channels, network connections, etc.) to be used by the subgraph.
120    pub write_prologue: TokenStream,
121    /// Iterator (or pusherator) code inside the subgraphs. The code for each
122    /// operator is emitted in order.
123    ///
124    /// Emitted code should assign to [`WriteContextArgs::ident`] and use
125    /// [`WriteContextArgs::inputs`] (pull `Stream`s) or
126    /// [`WriteContextArgs::outputs`] (push `Sink`s).
127    pub write_iterator: TokenStream,
128    /// Code which runs after `Stream`s/`Sink`s have been run. Mainly for flushing IO.
129    pub write_iterator_after: TokenStream,
130    /// Code which runs at the end of each tick, after all subgraphs have run.
131    /// Used for resetting state with `'tick` persistence.
132    pub write_tick_end: TokenStream,
133}
134
135/// Convenience range: zero or more (any number).
136pub const RANGE_ANY: &'static dyn RangeTrait<usize> = &(0..);
137/// Convenience range: exactly zero.
138pub const RANGE_0: &'static dyn RangeTrait<usize> = &(0..=0);
139/// Convenience range: exactly one.
140pub const RANGE_1: &'static dyn RangeTrait<usize> = &(1..=1);
141
142/// Helper to write the `write_iterator` portion of [`OperatorConstraints::write_fn`] output for
143/// unary identity operators.
144pub fn identity_write_iterator_fn(
145    &WriteContextArgs {
146        root,
147        op_span,
148        ident,
149        inputs,
150        outputs,
151        is_pull,
152        op_inst:
153            OperatorInstance {
154                generics: OpInstGenerics { type_args, .. },
155                ..
156            },
157        ..
158    }: &WriteContextArgs,
159) -> TokenStream {
160    let generic_type = type_args
161        .first()
162        .map(quote::ToTokens::to_token_stream)
163        .unwrap_or(quote_spanned!(op_span=> _));
164
165    if is_pull {
166        let input = &inputs[0];
167        quote_spanned! {op_span=>
168            let #ident = {
169                fn check_input<Pull, Item>(pull: Pull) -> impl #root::dfir_pipes::pull::Pull<Item = Item, Meta = Pull::Meta, CanPend = Pull::CanPend, CanEnd = Pull::CanEnd>
170                where
171                    Pull: #root::dfir_pipes::pull::Pull<Item = Item>,
172                {
173                    pull
174                }
175                check_input::<_, #generic_type>(#input)
176            };
177        }
178    } else {
179        let output = &outputs[0];
180        quote_spanned! {op_span=>
181            let #ident = {
182                fn check_output<Psh, Item>(push: Psh) -> impl #root::dfir_pipes::push::Push<Item, (), CanPend = Psh::CanPend>
183                where
184                    Psh: #root::dfir_pipes::push::Push<Item, ()>,
185                {
186                    push
187                }
188                check_output::<_, #generic_type>(#output)
189            };
190        }
191    }
192}
193
194/// [`OperatorConstraints::write_fn`] for unary identity operators.
195pub const IDENTITY_WRITE_FN: WriteFn = |write_context_args, _| {
196    let write_iterator = identity_write_iterator_fn(write_context_args);
197    Ok(OperatorWriteOutput {
198        write_iterator,
199        ..Default::default()
200    })
201};
202
203/// Helper to write the `write_iterator` portion of [`OperatorConstraints::write_fn`] output for
204/// the null operator - an operator that ignores all inputs and produces no output.
205pub fn null_write_iterator_fn(
206    &WriteContextArgs {
207        root,
208        op_span,
209        ident,
210        inputs,
211        outputs,
212        is_pull,
213        op_inst:
214            OperatorInstance {
215                generics: OpInstGenerics { type_args, .. },
216                ..
217            },
218        ..
219    }: &WriteContextArgs,
220) -> TokenStream {
221    let default_type = parse_quote_spanned! {op_span=> _};
222    let iter_type = type_args.first().unwrap_or(&default_type);
223
224    if is_pull {
225        quote_spanned! {op_span=>
226            let #ident = #root::dfir_pipes::pull::poll_fn({
227                #(
228                    let mut #inputs = ::std::boxed::Box::pin(#inputs);
229                )*
230                move |_cx| {
231                    // Make sure to poll all `#inputs` to completion.
232                    // NOTE(mingwei): `null()` can only have 0 or 1 inputs, though.
233                    // TODO(mingwei): Do we actually need to poll to completion or can we short-circuit?
234                    #(
235                        let #inputs = #root::dfir_pipes::pull::Pull::pull(
236                            ::std::pin::Pin::as_mut(&mut #inputs),
237                            <_ as #root::dfir_pipes::Context>::from_task(_cx),
238                        );
239                    )*
240                    #(
241                        if let #root::dfir_pipes::pull::PullStep::Pending(_) = #inputs {
242                            return #root::dfir_pipes::pull::PullStep::Pending(#root::dfir_pipes::Yes);
243                        }
244                    )*
245                    #root::dfir_pipes::pull::PullStep::<_, _, #root::dfir_pipes::Yes, _>::Ended(#root::dfir_pipes::Yes)
246                }
247            });
248        }
249    } else {
250        quote_spanned! {op_span=>
251            #[allow(clippy::let_unit_value)]
252            let _ = (#(#outputs),*);
253            let #ident = #root::dfir_pipes::push::for_each::<_, #iter_type>(::std::mem::drop::<#iter_type>);
254        }
255    }
256}
257
258/// [`OperatorConstraints::write_fn`] for the null operator - an operator that ignores all inputs
259/// and produces no output.
260pub const NULL_WRITE_FN: WriteFn = |write_context_args, _| {
261    let write_iterator = null_write_iterator_fn(write_context_args);
262    Ok(OperatorWriteOutput {
263        write_iterator,
264        ..Default::default()
265    })
266};
267
268macro_rules! declare_ops {
269    ( $( $mod:ident :: $op:ident, )* ) => {
270        $( pub(crate) mod $mod; )*
271        /// All DFIR operators.
272        pub const OPERATORS: &[OperatorConstraints] = &[
273            $( $mod :: $op, )*
274        ];
275    };
276}
277declare_ops![
278    all_iterations::ALL_ITERATIONS,
279    all_once::ALL_ONCE,
280    anti_join::ANTI_JOIN,
281    assert::ASSERT,
282    assert_eq::ASSERT_EQ,
283    batch::BATCH,
284    chain::CHAIN,
285    chain_first_n::CHAIN_FIRST_N,
286    _counter::_COUNTER,
287    cross_join::CROSS_JOIN,
288    cross_join_multiset::CROSS_JOIN_MULTISET,
289    cross_singleton::CROSS_SINGLETON,
290    demux_enum::DEMUX_ENUM,
291    dest_file::DEST_FILE,
292    dest_sink::DEST_SINK,
293    dest_sink_serde::DEST_SINK_SERDE,
294    difference::DIFFERENCE,
295    enumerate::ENUMERATE,
296    filter::FILTER,
297    filter_map::FILTER_MAP,
298    flat_map::FLAT_MAP,
299    flat_map_stream_blocking::FLAT_MAP_STREAM_BLOCKING,
300    flatten::FLATTEN,
301    flatten_stream_blocking::FLATTEN_STREAM_BLOCKING,
302    fold::FOLD,
303    fold_no_replay::FOLD_NO_REPLAY,
304    for_each::FOR_EACH,
305    identity::IDENTITY,
306    initialize::INITIALIZE,
307    inspect::INSPECT,
308    join::JOIN,
309    join_fused::JOIN_FUSED,
310    join_fused_lhs::JOIN_FUSED_LHS,
311    join_fused_rhs::JOIN_FUSED_RHS,
312    join_multiset::JOIN_MULTISET,
313    join_multiset_half::JOIN_MULTISET_HALF,
314    fold_keyed::FOLD_KEYED,
315    reduce_keyed::REDUCE_KEYED,
316    repeat_n::REPEAT_N,
317    // last_iteration::LAST_ITERATION,
318    lattice_bimorphism::LATTICE_BIMORPHISM,
319    _lattice_fold_batch::_LATTICE_FOLD_BATCH,
320    lattice_fold::LATTICE_FOLD,
321    _lattice_join_fused_join::_LATTICE_JOIN_FUSED_JOIN,
322    lattice_reduce::LATTICE_REDUCE,
323    map::MAP,
324    union::UNION,
325    multiset_delta::MULTISET_DELTA,
326    next_iteration::NEXT_ITERATION,
327    defer_signal::DEFER_SIGNAL,
328    defer_tick::DEFER_TICK,
329    defer_tick_lazy::DEFER_TICK_LAZY,
330    null::NULL,
331    partition::PARTITION,
332    persist::PERSIST,
333    persist_mut::PERSIST_MUT,
334    persist_mut_keyed::PERSIST_MUT_KEYED,
335    prefix::PREFIX,
336    resolve_futures::RESOLVE_FUTURES,
337    resolve_futures_blocking::RESOLVE_FUTURES_BLOCKING,
338    resolve_futures_blocking_ordered::RESOLVE_FUTURES_BLOCKING_ORDERED,
339    resolve_futures_ordered::RESOLVE_FUTURES_ORDERED,
340    reduce::REDUCE,
341    reduce_no_replay::REDUCE_NO_REPLAY,
342    scan::SCAN,
343    scan_async_blocking::SCAN_ASYNC_BLOCKING,
344    spin::SPIN,
345    sort::SORT,
346    sort_by_key::SORT_BY_KEY,
347    source_file::SOURCE_FILE,
348    source_interval::SOURCE_INTERVAL,
349    source_iter::SOURCE_ITER,
350    source_json::SOURCE_JSON,
351    source_stdin::SOURCE_STDIN,
352    source_stream::SOURCE_STREAM,
353    source_stream_serde::SOURCE_STREAM_SERDE,
354    state::STATE,
355    state_by::STATE_BY,
356    tee::TEE,
357    unique::UNIQUE,
358    unzip::UNZIP,
359    zip::ZIP,
360    zip_longest::ZIP_LONGEST,
361];
362
363/// Get the operator lookup table, generating it if needed.
364pub fn operator_lookup() -> &'static HashMap<&'static str, &'static OperatorConstraints> {
365    pub static OPERATOR_LOOKUP: OnceLock<HashMap<&'static str, &'static OperatorConstraints>> =
366        OnceLock::new();
367    OPERATOR_LOOKUP.get_or_init(|| OPERATORS.iter().map(|op| (op.name, op)).collect())
368}
369/// Find an operator by [`GraphNode`].
370pub fn find_node_op_constraints(node: &GraphNode) -> Option<&'static OperatorConstraints> {
371    if let GraphNode::Operator(operator) = node {
372        find_op_op_constraints(operator)
373    } else {
374        None
375    }
376}
377/// Find an operator by an AST [`Operator`].
378pub fn find_op_op_constraints(operator: &Operator) -> Option<&'static OperatorConstraints> {
379    let name = &*operator.name_string();
380    operator_lookup().get(name).copied()
381}
382
383/// Context arguments provided to [`OperatorConstraints::write_fn`].
384#[derive(Clone)]
385pub struct WriteContextArgs<'a> {
386    /// `dfir` crate name for `use #root::something`.
387    pub root: &'a TokenStream,
388    /// `context` ident, the name of the provided
389    /// [`dfir_rs::scheduled::Context`](https://hydro.run/rustdoc/dfir_rs/scheduled/context/struct.Context.html).
390    pub context: &'a Ident,
391    /// `df` ident, the name of the
392    /// [`dfir_rs::scheduled::graph::Dfir`](https://hydro.run/rustdoc/dfir_rs/scheduled/graph/struct.Dfir.html)
393    /// instance.
394    pub df_ident: &'a Ident,
395    /// Subgraph ID in which this operator is contained.
396    pub subgraph_id: GraphSubgraphId,
397    /// Node ID identifying this operator in the flat or partitioned graph meta-datastructure.
398    pub node_id: GraphNodeId,
399    /// Loop ID in which this operator is contained, or `None` if not in a loop.
400    pub loop_id: Option<GraphLoopId>,
401    /// The source span of this operator.
402    pub op_span: Span,
403    /// Tag for this operator appended to the generated identifier.
404    pub op_tag: Option<String>,
405    /// Identifier for a function to call when doing work outside the stream.
406    pub work_fn: &'a Ident,
407    /// Identifier for a function to wrap futures when doing work outside the stream.
408    pub work_fn_async: &'a Ident,
409
410    /// Ident the `Stream` or `Sink` should be assigned to.
411    pub ident: &'a Ident,
412    /// If a pull `Stream` (true) or push `Sink` (false) should be used.
413    pub is_pull: bool,
414    /// Input `Stream` operator idents (or ref idents; used for pull).
415    pub inputs: &'a [Ident],
416    /// Output `Sink` operator idents (or ref idents; used for push).
417    pub outputs: &'a [Ident],
418    /// Ident for the singleton output of this operator, if any.
419    pub singleton_output_ident: &'a Ident,
420
421    /// Operator name.
422    pub op_name: &'static str,
423    /// Operator instance arguments object.
424    pub op_inst: &'a OperatorInstance,
425    /// Arguments provided by the user into the operator as arguments.
426    /// I.e. the `a, b, c` in `-> my_op(a, b, c) -> `.
427    ///
428    /// These arguments include singleton postprocessing codegen, with
429    /// [`std::cell::RefCell::borrow_mut`] code pre-generated.
430    pub arguments: &'a Punctuated<Expr, Token![,]>,
431}
432impl WriteContextArgs<'_> {
433    /// Generate a (almost certainly) unique identifier with the given suffix.
434    ///
435    /// Includes the subgraph and node IDs in the generated identifier.
436    ///
437    /// This will always return the same identifier for a given `suffix`.
438    pub fn make_ident(&self, suffix: impl AsRef<str>) -> Ident {
439        Ident::new(
440            &format!(
441                "sg_{:?}_node_{:?}_{}",
442                self.subgraph_id.data(),
443                self.node_id.data(),
444                suffix.as_ref(),
445            ),
446            self.op_span,
447        )
448    }
449
450    /// Returns the given number of persistence arguments, disallowing mutable lifetimes.
451    pub fn persistence_args_disallow_mutable<const N: usize>(
452        &self,
453        diagnostics: &mut Diagnostics,
454    ) -> [Persistence; N] {
455        let len = self.op_inst.generics.persistence_args.len();
456        if 0 != len && 1 != len && N != len {
457            diagnostics.push(Diagnostic::spanned(
458                self.op_span,
459                Level::Error,
460                format!(
461                    "The operator `{}` only accepts 0, 1, or {} persistence arguments",
462                    self.op_name, N
463                ),
464            ));
465        }
466
467        let default_persistence = if self.loop_id.is_some() {
468            Persistence::None
469        } else {
470            Persistence::Tick
471        };
472        let mut out = [default_persistence; N];
473        self.op_inst
474            .generics
475            .persistence_args
476            .iter()
477            .copied()
478            .cycle() // Re-use the first element for both persistences.
479            .take(N)
480            .enumerate()
481            .filter(|&(_i, p)| {
482                if p == Persistence::Mutable {
483                    diagnostics.push(Diagnostic::spanned(
484                        self.op_span,
485                        Level::Error,
486                        format!(
487                            "An implementation of `'{}` does not exist",
488                            p.to_str_lowercase()
489                        ),
490                    ));
491                    false
492                } else {
493                    true
494                }
495            })
496            .for_each(|(i, p)| {
497                out[i] = p;
498            });
499        out
500    }
501}
502
503/// An object-safe version of [`RangeBounds`].
504pub trait RangeTrait<T>: Send + Sync + Debug
505where
506    T: ?Sized,
507{
508    /// Start (lower) bound.
509    fn start_bound(&self) -> Bound<&T>;
510    /// End (upper) bound.
511    fn end_bound(&self) -> Bound<&T>;
512    /// Returns if `item` is contained in this range.
513    fn contains(&self, item: &T) -> bool
514    where
515        T: PartialOrd<T>;
516
517    /// Turn this range into a human-readable string.
518    fn human_string(&self) -> String
519    where
520        T: Display + PartialEq,
521    {
522        match (self.start_bound(), self.end_bound()) {
523            (Bound::Unbounded, Bound::Unbounded) => "any number of".to_owned(),
524
525            (Bound::Included(n), Bound::Included(x)) if n == x => {
526                format!("exactly {}", n)
527            }
528            (Bound::Included(n), Bound::Included(x)) => {
529                format!("at least {} and at most {}", n, x)
530            }
531            (Bound::Included(n), Bound::Excluded(x)) => {
532                format!("at least {} and less than {}", n, x)
533            }
534            (Bound::Included(n), Bound::Unbounded) => format!("at least {}", n),
535            (Bound::Excluded(n), Bound::Included(x)) => {
536                format!("more than {} and at most {}", n, x)
537            }
538            (Bound::Excluded(n), Bound::Excluded(x)) => {
539                format!("more than {} and less than {}", n, x)
540            }
541            (Bound::Excluded(n), Bound::Unbounded) => format!("more than {}", n),
542            (Bound::Unbounded, Bound::Included(x)) => format!("at most {}", x),
543            (Bound::Unbounded, Bound::Excluded(x)) => format!("less than {}", x),
544        }
545    }
546}
547
548impl<R, T> RangeTrait<T> for R
549where
550    R: RangeBounds<T> + Send + Sync + Debug,
551{
552    fn start_bound(&self) -> Bound<&T> {
553        self.start_bound()
554    }
555
556    fn end_bound(&self) -> Bound<&T> {
557        self.end_bound()
558    }
559
560    fn contains(&self, item: &T) -> bool
561    where
562        T: PartialOrd<T>,
563    {
564        self.contains(item)
565    }
566}
567
568/// Persistence lifetimes: `'none`, `'tick`, `'static`, or `'mutable`.
569#[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Debug, Serialize, Deserialize)]
570pub enum Persistence {
571    /// No persistence, for within a loop iteration.
572    None,
573    /// Persistence throughout a single loop execution, across iterations.
574    Loop,
575    /// Persistence for one tick, at the top-level only (outside any loops).
576    Tick,
577    /// Persistence across all ticks.
578    Static,
579    /// The static lifetime but allowing non-monotonic mutability.
580    Mutable,
581}
582impl Persistence {
583    /// Returns a lowercase string for the persistence type.
584    pub fn to_str_lowercase(self) -> &'static str {
585        match self {
586            Persistence::None => "none",
587            Persistence::Tick => "tick",
588            Persistence::Loop => "loop",
589            Persistence::Static => "static",
590            Persistence::Mutable => "mutable",
591        }
592    }
593}
594
595/// Helper which creates a error message string literal for when the Tokio runtime is not found.
596fn make_missing_runtime_msg(op_name: &str) -> Literal {
597    Literal::string(&format!(
598        "`{}()` must be used within a Tokio runtime. For example, use `#[dfir_rs::main]` on your main method.",
599        op_name
600    ))
601}
602
603/// Operator categories, for docs.
604#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, DocumentedVariants)]
605pub enum OperatorCategory {
606    /// Maps: Simple one-in-one-out operators.
607    Map,
608    /// Filters: One-in zero-or-one-out operators.
609    Filter,
610    /// Flattens: One-in multiple-out operators.
611    Flatten,
612    /// Folds: Operators which accumulate elements together.
613    Fold,
614    /// Keyed Folds: Operators which accumulate elements together by key.
615    KeyedFold,
616    /// Lattice Folds: Folds based on lattice-merge.
617    LatticeFold,
618    /// Persistent Operators: Persistent (stateful) operators.
619    Persistence,
620    /// Multi-Input Operators: Operators with multiple inputs.
621    MultiIn,
622    /// Multi-Output Operators: Operators with multiple outputs.
623    MultiOut,
624    /// Sources: Operators which produce output elements (and consume no inputs).
625    Source,
626    /// Sinks: Operators which consume input elements (and produce no outputs).
627    Sink,
628    /// Control Flow Operators: Operators which affect control flow/scheduling.
629    Control,
630    /// Compiler Fusion Operators: Operators which are necessary to implement certain optimizations and rewrite rules.
631    CompilerFusionOperator,
632    /// Windowing Operators: Operators for windowing `loop` inputs.
633    Windowing,
634    /// Un-Windowing Operators: Operators for collecting `loop` outputs.
635    Unwindowing,
636}
637impl OperatorCategory {
638    /// Human-readible heading name, for docs.
639    pub fn name(self) -> &'static str {
640        self.get_variant_docs().split_once(":").unwrap().0
641    }
642    /// Human description, for docs.
643    pub fn description(self) -> &'static str {
644        self.get_variant_docs().split_once(":").unwrap().1
645    }
646}
647
648/// Operator type for Flo semantics.
649#[derive(Clone, Copy, PartialOrd, Ord, PartialEq, Eq, Debug)]
650pub enum FloType {
651    /// A source operator, which must be at the top level.
652    Source,
653    /// A windowing operator, for moving data into a loop context.
654    Windowing,
655    /// An un-windowing operator, for moving data out of a loop context.
656    Unwindowing,
657    /// Moves data into the next loop iteration within a loop context.
658    NextIteration,
659}