qubit-function 0.14.0

Functional programming traits and Box/Rc/Arc adapters for Rust, inspired by Java functional interfaces
Documentation 
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/*******************************************************************************
 *
 *    Copyright (c) 2025 - 2026 Haixing Hu.
 *
 *    SPDX-License-Identifier: Apache-2.0
 *
 *    Licensed under the Apache License, Version 2.0.
 *
 ******************************************************************************/
// qubit-style: allow explicit-imports
//! Defines the `BoxStatefulFunction` public type.

use super::{
    BoxConditionalStatefulFunction,
    BoxFunctionOnce,
    Predicate,
    RcStatefulFunction,
    StatefulFunction,
    impl_box_conversions,
    impl_box_function_methods,
    impl_function_common_methods,
    impl_function_constant_method,
    impl_function_debug_display,
    impl_function_identity_method,
};

// ============================================================================
// BoxStatefulFunction - Box<dyn FnMut(&T) -> R>
// ============================================================================

/// BoxStatefulFunction - stateful function wrapper based on `Box<dyn FnMut>`
///
/// A stateful function wrapper that provides single ownership with reusable stateful
/// transformation. The stateful function consumes the input and can be called
/// multiple times while maintaining internal state.
///
/// # Features
///
/// - **Based on**: `Box<dyn FnMut(&T) -> R>`
/// - **Ownership**: Single ownership, cannot be cloned
/// - **Reusability**: Can be called multiple times (each call consumes
///   its input)
/// - **Thread Safety**: Not thread-safe (no `Send + Sync` requirement)
/// - **Statefulness**: Can modify internal state between calls
///
pub struct BoxStatefulFunction<T, R> {
    pub(super) function: Box<dyn FnMut(&T) -> R>,
    pub(super) name: Option<String>,
}

impl<T, R> BoxStatefulFunction<T, R> {
    // Generates: new(), new_with_name(), new_with_optional_name(), name(), set_name()
    impl_function_common_methods!(
        BoxStatefulFunction<T, R>,
        (FnMut(&T) -> R + 'static),
        |f| Box::new(f)
    );

    // Generates: when(), and_then(), compose()
    impl_box_function_methods!(
        BoxStatefulFunction<T, R>,
        BoxConditionalStatefulFunction,
        StatefulFunction
    );
}

// Generates: constant() method for BoxStatefulFunction<T, R>
impl_function_constant_method!(BoxStatefulFunction<T, R>, 'static);

// Generates: identity() method for BoxStatefulFunction<T, T>
impl_function_identity_method!(BoxStatefulFunction<T, T>);

// Generates: Debug and Display implementations for BoxStatefulFunction<T, R>
impl_function_debug_display!(BoxStatefulFunction<T, R>);

// Implement StatefulFunction trait for BoxStatefulFunction<T, R>
impl<T, R> StatefulFunction<T, R> for BoxStatefulFunction<T, R> {
    fn apply(&mut self, t: &T) -> R {
        (self.function)(t)
    }

    // Generates: into_box(), into_rc(), into_fn(), into_once()
    impl_box_conversions!(
        BoxStatefulFunction<T, R>,
        RcStatefulFunction,
        FnMut(&T) -> R,
        BoxFunctionOnce
    );
}