zrx_stream/stream/operator/
map.rs

1// Copyright (c) 2025-2026 Zensical and contributors
2
3// SPDX-License-Identifier: MIT
4// All contributions are certified under the DCO
5
6// Permission is hereby granted, free of charge, to any person obtaining a copy
7// of this software and associated documentation files (the "Software"), to
8// deal in the Software without restriction, including without limitation the
9// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
10// sell copies of the Software, and to permit persons to whom the Software is
11// furnished to do so, subject to the following conditions:
12
13// The above copyright notice and this permission notice shall be included in
14// all copies or substantial portions of the Software.
15
16// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
17// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
18// FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
19// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
20// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
21// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
22// IN THE SOFTWARE.
23
24// ----------------------------------------------------------------------------
25
26//! Map operator.
27
28use std::marker::PhantomData;
29
30use zrx_scheduler::action::context::Binding;
31use zrx_scheduler::action::{Action, Context};
32use zrx_scheduler::step::IntoSteps;
33use zrx_scheduler::{Id, Value};
34
35use crate::stream::function::MapFn;
36use crate::stream::Stream;
37
38use super::Operator;
39
40// ----------------------------------------------------------------------------
41// Structs
42// ----------------------------------------------------------------------------
43
44/// Map operator.
45pub struct Map<T, F, U> {
46    /// Operator function.
47    function: F,
48    /// Capture types.
49    marker: PhantomData<(T, U)>,
50}
51
52// ----------------------------------------------------------------------------
53// Implementations
54// ----------------------------------------------------------------------------
55
56impl<I, T> Stream<I, T>
57where
58    I: Id,
59    T: Value,
60{
61    /// Maps the stream using the provided function.
62    #[inline]
63    #[must_use]
64    pub fn map<F, U>(&self, f: F) -> Stream<I, U>
65    where
66        F: MapFn<I, T, U> + Clone,
67        U: Value,
68    {
69        self.subscribe(Map {
70            function: f,
71            marker: PhantomData,
72        })
73    }
74}
75
76// ----------------------------------------------------------------------------
77// Trait implementations
78// ----------------------------------------------------------------------------
79
80impl<I, T, F, U> Action<I> for Map<T, F, U>
81where
82    I: Id,
83    T: Value,
84    F: MapFn<I, T, U> + Clone,
85    U: Value,
86{
87    type Inputs = (T,);
88    type Output<'a> = U;
89
90    /// Executes the operator.
91    fn execute(&mut self, ctx: Context<I, Self>) -> impl IntoSteps<I, Self> {
92        let Binding { scopes, inputs, mut output, .. } = ctx.bind();
93        scopes.map(move |scope| {
94            let Some(value) = inputs.get(&scope).cloned() else {
95                output.remove(&scope);
96                return scope.done();
97            };
98            scope.task().build({
99                let function = self.function.clone();
100                move || {
101                    let value = function.execute(&scope, &value)?;
102                    scope.then().build(move |mut ctx| {
103                        let mut output = ctx.output().expect("invariant");
104                        output.insert((*scope).clone(), value);
105                        scope.done()
106                    })
107                }
108            })
109        })
110    }
111}
zrx_stream/stream/operator/map.rs

zrx_stream/stream/operator/
map.rs
