qubit_function/functions/function_once/
box_function_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 `BoxFunctionOnce` public type.
12
13use super::{
14    BoxConditionalFunctionOnce,
15    FunctionOnce,
16    Predicate,
17    impl_box_function_methods,
18    impl_box_once_conversions,
19    impl_closure_once_trait,
20    impl_function_common_methods,
21    impl_function_constant_method,
22    impl_function_debug_display,
23    impl_function_identity_method,
24};
25
26// ============================================================================
27// BoxFunctionOnce - Box<dyn FnOnce(&T) -> R>
28// ============================================================================
29
30/// BoxFunctionOnce - consuming transformer wrapper based on
31/// `Box<dyn FnOnce>`
32///
33/// A transformer wrapper that provides single ownership with one-time use
34/// semantics. Consumes both self and the input value.
35///
36/// # Features
37///
38/// - **Based on**: `Box<dyn FnOnce(&T) -> R>`
39/// - **Ownership**: Single ownership, cannot be cloned
40/// - **Reusability**: Can only be called once (consumes self and input)
41/// - **Thread Safety**: Not thread-safe (no `Send + Sync` requirement)
42///
43pub struct BoxFunctionOnce<T, R> {
44    pub(super) function: Box<dyn FnOnce(&T) -> R>,
45    pub(super) name: Option<String>,
46}
47
48impl<T, R> BoxFunctionOnce<T, R> {
49    // Generates: new(), new_with_name(), new_with_optional_name(), name(), set_name()
50    impl_function_common_methods!(
51        BoxFunctionOnce<T, R>,
52        (FnOnce(&T) -> R + 'static),
53        |f| Box::new(f)
54    );
55
56    // Generates: when(), and_then(), compose()
57    impl_box_function_methods!(
58        BoxFunctionOnce<T, R>,
59        BoxConditionalFunctionOnce,
60        FunctionOnce
61    );
62}
63
64impl<T, R> FunctionOnce<T, R> for BoxFunctionOnce<T, R> {
65    fn apply(self, input: &T) -> R {
66        (self.function)(input)
67    }
68
69    impl_box_once_conversions!(
70        BoxFunctionOnce<T, R>,
71        FunctionOnce,
72        FnOnce(&T) -> R
73    );
74}
75
76// Generates: constant() method for BoxFunctionOnce<T, R>
77impl_function_constant_method!(BoxFunctionOnce<T, R>, 'static);
78
79// Generates: identity() method for BoxFunctionOnce<T, T>
80impl_function_identity_method!(BoxFunctionOnce<T, T>);
81
82// Generates: Debug and Display implementations for BoxFunctionOnce<T, R>
83impl_function_debug_display!(BoxFunctionOnce<T, R>);
84
85// ============================================================================
86// Blanket implementation for standard FnOnce trait
87// ============================================================================
88
89// Implement FunctionOnce for all FnOnce(&T) -> R using macro
90impl_closure_once_trait!(
91    FunctionOnce<T, R>,
92    apply,
93    BoxFunctionOnce,
94    FnOnce(input: &T) -> R
95);
qubit_function/functions/function_once/box_function_once.rs

qubit_function/functions/function_once/
box_function_once.rs
