qubit_function/transformers/stateful_transformer/
box_stateful_transformer.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 `BoxStatefulTransformer` public type.
12
13#![allow(unused_imports)]
14
15use super::*;
16
17// ============================================================================
18// BoxStatefulTransformer - Box<dyn FnMut(T) -> R>
19// ============================================================================
20
21/// BoxStatefulTransformer - transformer wrapper based on `Box<dyn FnMut>`
22///
23/// A transformer wrapper that provides single ownership with reusable stateful
24/// transformation. The transformer consumes the input and can be called
25/// multiple times while maintaining internal state.
26///
27/// # Features
28///
29/// - **Based on**: `Box<dyn FnMut(T) -> R>`
30/// - **Ownership**: Single ownership, cannot be cloned
31/// - **Reusability**: Can be called multiple times (each call consumes
32///   its input)
33/// - **Thread Safety**: Not thread-safe (no `Send + Sync` requirement)
34/// - **Statefulness**: Can modify internal state between calls
35///
36pub struct BoxStatefulTransformer<T, R> {
37    pub(super) function: Box<dyn FnMut(T) -> R>,
38    pub(super) name: Option<String>,
39}
40
41impl<T, R> BoxStatefulTransformer<T, R> {
42    impl_transformer_common_methods!(
43        BoxStatefulTransformer<T, R>,
44        (FnMut(T) -> R + 'static),
45        |f| Box::new(f)
46    );
47
48    impl_box_transformer_methods!(
49        BoxStatefulTransformer<T, R>,
50        BoxConditionalStatefulTransformer,
51        StatefulTransformer
52    );
53}
54
55// Implement constant method for BoxStatefulTransformer
56impl_transformer_constant_method!(stateful BoxStatefulTransformer<T, R>);
57
58// Implement Debug and Display for BoxStatefulTransformer
59impl_transformer_debug_display!(BoxStatefulTransformer<T, R>);
60
61// Implement StatefulTransformer trait for BoxStatefulTransformer
62impl<T, R> StatefulTransformer<T, R> for BoxStatefulTransformer<T, R> {
63    fn apply(&mut self, input: T) -> R {
64        (self.function)(input)
65    }
66
67    // Generates: into_box(), into_rc(), into_fn(), into_once()
68    impl_box_conversions!(
69        BoxStatefulTransformer<T, R>,
70        RcStatefulTransformer,
71        FnMut(T) -> R,
72        BoxTransformerOnce
73    );
74
75    // do NOT override StatefulTransformer::to_xxx() because BoxStatefulTransformer is not Clone
76    // and calling BoxStatefulTransformer::to_xxx() will cause a compile error
77}
qubit_function/transformers/stateful_transformer/box_stateful_transformer.rs

qubit_function/transformers/stateful_transformer/
box_stateful_transformer.rs
