qubit-function 0.16.0

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

use {
    crate::BiConsumer,
    crate::BiPredicate,
    crate::RcBiConsumer,
    crate::RcBiPredicate,
    crate::consumers::macros::impl_conditional_consumer_clone,
    crate::consumers::macros::impl_conditional_consumer_debug_display,
    crate::consumers::macros::impl_shared_conditional_consumer,
};

// =======================================================================
// 9. RcConditionalBiConsumer - Rc-based Conditional BiConsumer
// =======================================================================

/// RcConditionalBiConsumer struct
///
/// A conditional bi-consumer that wraps an `RcBiConsumer` and only executes
/// when a predicate is satisfied. Based on `Rc` for single-threaded shared
/// ownership.
///
/// # Features
///
/// - **Shared Ownership**: Cloneable through `Rc`, allows multiple owners
/// - **Single-Threaded**: Uses non-atomic `Rc`; choose `Arc` when thread-safe
///   sharing is required, and benchmark the real workload when cost matters
/// - **Conditional Execution**: Only consumes when predicate returns `true`
/// - **Implements BiConsumer**: Can be used anywhere a `BiConsumer` is expected
/// - **Shared access**: Receives shared references; interior mutability and
///   external side effects remain possible
#[must_use = "callback wrappers do nothing unless stored or invoked"]
pub struct RcConditionalBiConsumer<T, U> {
    /// The wrapped consumer callback.
    pub(super) consumer: RcBiConsumer<T, U>,
    /// The predicate controlling conditional execution.
    pub(super) predicate: RcBiPredicate<T, U>,
}

// Use macro to generate conditional bi-consumer implementations
impl_shared_conditional_consumer!(
    RcConditionalBiConsumer<T, U>,
    RcBiConsumer,
    BiConsumer,
    callback_bounds = ('static)
);

// Hand-written BiConsumer trait implementation
impl<T, U> BiConsumer<T, U> for RcConditionalBiConsumer<T, U> {
    fn accept(&self, first: &T, second: &U) {
        if self.predicate.test(first, second) {
            self.consumer.accept(first, second);
        }
    }
}

// Use macro to generate Clone implementation
impl_conditional_consumer_clone!(RcConditionalBiConsumer<T, U>);

// Use macro to generate Debug and Display implementations
impl_conditional_consumer_debug_display!(RcConditionalBiConsumer<T, U>);