qubit-function 0.16.0

// =============================================================================
//    Copyright (c) 2025 - 2026 Haixing Hu.
//
//    SPDX-License-Identifier: Apache-2.0
//
//    Licensed under the Apache License, Version 2.0.
// =============================================================================
//! Defines the `BoxConditionalBiFunction` public type.

use {
    crate::BiFunction,
    crate::BiPredicate,
    crate::BoxBiFunction,
    crate::BoxBiPredicate,
    crate::functions::macros::impl_box_conditional_function,
    crate::functions::macros::impl_conditional_function_debug_display,
};

// ============================================================================
// BoxConditionalBiFunction - Box-based Conditional BiFunction
// ============================================================================

/// BoxConditionalBiFunction struct
///
/// A conditional bi-function that only executes when a bi-predicate is
/// satisfied. Uses `BoxBiFunction` and `BoxBiPredicate` for single
/// ownership semantics.
///
/// This type is typically created by calling `BoxBiFunction::when()` and is
/// designed to work with the `or_else()` method to create if-then-else logic.
///
/// # Features
///
/// - **Single Ownership**: Not cloneable, consumes `self` on use
/// - **Conditional Execution**: Only computes when bi-predicate returns `true`
/// - **Chainable**: Can add `or_else` branch to create if-then-else logic
/// - **Implements BiFunction**: Can be used anywhere a `BiFunction` is expected
///
/// # Examples
///
/// ## With or_else Branch
///
/// ```rust
/// use qubit_function::{BiFunction, BoxBiFunction};
///
/// let add = BoxBiFunction::new(|x: &i32, y: &i32| *x + *y);
/// let multiply = BoxBiFunction::new(|x: &i32, y: &i32| *x * *y);
/// let conditional = add.when(|x: &i32, y: &i32| *x > 0).or_else(multiply);
///
/// assert_eq!(conditional.apply(&5, &3), 8);  // when branch executed
/// assert_eq!(conditional.apply(&-5, &3), -15); // or_else branch executed
/// ```
#[must_use = "callback wrappers do nothing unless stored or invoked"]
pub struct BoxConditionalBiFunction<T, U, R> {
    /// The wrapped callback implementation.
    pub(super) function: BoxBiFunction<T, U, R>,
    /// The predicate controlling conditional execution.
    pub(super) predicate: BoxBiPredicate<T, U>,
}

// Implement BoxConditionalBiFunction
impl_box_conditional_function!(
    BoxConditionalBiFunction<T, U, R>,
    BoxBiFunction,
    BiFunction
);

// Use macro to generate Debug and Display implementations
impl_conditional_function_debug_display!(BoxConditionalBiFunction<T, U, R>);