qubit_function/transformers/transformer_once/
box_transformer_once.rs

1/*******************************************************************************
2 *
3 *    Copyright (c) 2025 - 2026 Haixing Hu.
4 *
5 *    SPDX-License-Identifier: Apache-2.0
6 *
7 *    Licensed under the Apache License, Version 2.0.
8 *
9 ******************************************************************************/
10// qubit-style: allow explicit-imports
11//! Defines the `BoxTransformerOnce` public type.
12
13use super::{
14    BoxConditionalTransformerOnce,
15    Predicate,
16    TransformerOnce,
17    impl_box_once_conversions,
18    impl_box_transformer_methods,
19    impl_closure_once_trait,
20    impl_transformer_common_methods,
21    impl_transformer_constant_method,
22    impl_transformer_debug_display,
23};
24
25// ============================================================================
26// BoxTransformerOnce - Box<dyn FnOnce(T) -> R>
27// ============================================================================
28
29/// BoxTransformerOnce - consuming transformer wrapper based on
30/// `Box<dyn FnOnce>`
31///
32/// A transformer wrapper that provides single ownership with one-time use
33/// semantics. Consumes both self and the input value.
34///
35/// # Features
36///
37/// - **Based on**: `Box<dyn FnOnce(T) -> R>`
38/// - **Ownership**: Single ownership, cannot be cloned
39/// - **Reusability**: Can only be called once (consumes self and input)
40/// - **Thread Safety**: Not thread-safe (no `Send + Sync` requirement)
41///
42pub struct BoxTransformerOnce<T, R> {
43    pub(super) function: Box<dyn FnOnce(T) -> R>,
44    pub(super) name: Option<String>,
45}
46
47// Implement BoxTransformerOnce
48impl<T, R> BoxTransformerOnce<T, R> {
49    impl_transformer_common_methods!(
50        BoxTransformerOnce<T, R>,
51        (FnOnce(T) -> R + 'static),
52        |f| Box::new(f)
53    );
54
55    impl_box_transformer_methods!(
56        BoxTransformerOnce<T, R>,
57        BoxConditionalTransformerOnce,
58        TransformerOnce
59    );
60}
61
62// Implement TransformerOnce trait for BoxTransformerOnce
63impl<T, R> TransformerOnce<T, R> for BoxTransformerOnce<T, R> {
64    fn apply(self, input: T) -> R {
65        (self.function)(input)
66    }
67
68    impl_box_once_conversions!(
69        BoxTransformerOnce<T, R>,
70        TransformerOnce,
71        FnOnce(T) -> R
72    );
73}
74
75// Implement constant method for BoxTransformerOnce
76impl_transformer_constant_method!(BoxTransformerOnce<T, R>);
77
78// Use macro to generate Debug and Display implementations
79impl_transformer_debug_display!(BoxTransformerOnce<T, R>);
80
81// ============================================================================
82// Blanket implementation for standard FnOnce trait
83// ============================================================================
84
85// Implement TransformerOnce for all FnOnce(T) -> R using macro
86impl_closure_once_trait!(
87    TransformerOnce<T, R>,
88    apply,
89    BoxTransformerOnce,
90    FnOnce(input: T) -> R
91);
qubit_function/transformers/transformer_once/box_transformer_once.rs

qubit_function/transformers/transformer_once/
box_transformer_once.rs
