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
13use super::{
14    BoxConditionalStatefulTransformer,
15    BoxTransformerOnce,
16    Predicate,
17    RcStatefulTransformer,
18    StatefulTransformer,
19    impl_box_conversions,
20    impl_box_transformer_methods,
21    impl_transformer_common_methods,
22    impl_transformer_constant_method,
23    impl_transformer_debug_display,
24};
25
26// ============================================================================
27// BoxStatefulTransformer - Box<dyn FnMut(T) -> R>
28// ============================================================================
29
30/// BoxStatefulTransformer - transformer wrapper based on `Box<dyn FnMut>`
31///
32/// A transformer wrapper that provides single ownership with reusable stateful
33/// transformation. The transformer consumes the input and can be called
34/// multiple times while maintaining internal state.
35///
36/// # Features
37///
38/// - **Based on**: `Box<dyn FnMut(T) -> R>`
39/// - **Ownership**: Single ownership, cannot be cloned
40/// - **Reusability**: Can be called multiple times (each call consumes
41///   its input)
42/// - **Thread Safety**: Not thread-safe (no `Send + Sync` requirement)
43/// - **Statefulness**: Can modify internal state between calls
44///
45pub struct BoxStatefulTransformer<T, R> {
46    pub(super) function: Box<dyn FnMut(T) -> R>,
47    pub(super) name: Option<String>,
48}
49
50impl<T, R> BoxStatefulTransformer<T, R> {
51    impl_transformer_common_methods!(
52        BoxStatefulTransformer<T, R>,
53        (FnMut(T) -> R + 'static),
54        |f| Box::new(f)
55    );
56
57    impl_box_transformer_methods!(
58        BoxStatefulTransformer<T, R>,
59        BoxConditionalStatefulTransformer,
60        StatefulTransformer
61    );
62}
63
64// Implement constant method for BoxStatefulTransformer
65impl_transformer_constant_method!(stateful BoxStatefulTransformer<T, R>);
66
67// Implement Debug and Display for BoxStatefulTransformer
68impl_transformer_debug_display!(BoxStatefulTransformer<T, R>);
69
70// Implement StatefulTransformer trait for BoxStatefulTransformer
71impl<T, R> StatefulTransformer<T, R> for BoxStatefulTransformer<T, R> {
72    fn apply(&mut self, input: T) -> R {
73        (self.function)(input)
74    }
75
76    // Generates: into_box(), into_rc(), into_fn(), into_once()
77    impl_box_conversions!(
78        BoxStatefulTransformer<T, R>,
79        RcStatefulTransformer,
80        FnMut(T) -> R,
81        BoxTransformerOnce
82    );
83
84    // do NOT override StatefulTransformer::to_xxx() because BoxStatefulTransformer is not Clone
85    // and calling BoxStatefulTransformer::to_xxx() will cause a compile error
86}
qubit_function/transformers/stateful_transformer/box_stateful_transformer.rs

qubit_function/transformers/stateful_transformer/
box_stateful_transformer.rs
