1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
// Copyright (c) 2025-2026 Zensical and contributors
// SPDX-License-Identifier: MIT
// All contributions are certified under the DCO
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to
// deal in the Software without restriction, including without limitation the
// rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
// sell copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
// FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
// IN THE SOFTWARE.
// ----------------------------------------------------------------------------
//! Action.
use ;
use ;
use IntoSteps;
pub use Context;
pub use ;
pub use Options;
// ----------------------------------------------------------------------------
// Traits
// ----------------------------------------------------------------------------
/// Action.
///
/// Actions represent units of work that can be executed by a [`Scheduler`][]
/// in a type-safe manner. Each action must define two associated types:
///
/// - [`Action::Inputs`], which defines the input types of the action, sourced
/// from the outputs of other actions that are considered its dependencies.
///
/// - [`Action::Output`], which defines the output type of the action, turning
/// the action into a dependency for dependent actions downstream.
///
/// This makes actions reusable and composable, as they are fundamentally just
/// functions with typed inputs and outputs, which can be dynamically connected
/// and executed by the scheduler in topological order. The input types of an
/// action must implement [`TryAsStorages`], which ensures that the scheduler
/// can downcast the type-erased upstream [`Storage`][] instances into concrete
/// types the action can work with. The output type of an action must implement
/// [`TryAsStorageMut`], ensuring that the action can store its output in a
/// concrete [`Storage`][] to pass it to downstream actions as input.
///
/// The [`Action`] type is passed as `Self` to [`Context`] and [`IntoEffects`],
/// two types that are used to provide an action with the necessary context and
/// ability to return [`Effects`], to instruct the scheduler to perform certain
/// operations like [`Task`][] scheduling or [`Timer`][] registration. The type
/// parameter is erased by the scheduler when registering and executing actions
/// through the implementation of the [`Tag`][] trait.
///
/// Note that actions themselves cannot be dyn-compatible, as they require the
/// [`Sized`] bound to pass `Self` to [`Context`] and [`IntoEffects`]. Also note
/// that the [`Action::Output`] associated type must be generic over a lifetime,
/// as this is necessary to derive the output type from the input types.
///
/// [`Scheduler`]: crate::scheduler::Scheduler
/// [`Storage`]: zrx_storage::Storage
/// [`Tag`]: crate::scheduler::engine::Tag
/// [`Task`]: crate::scheduler::effect::Task
/// [`Timer`]: crate::scheduler::effect::Timer