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use super::{leptonica_destroy::LeptonicaDestroy, LeptonicaClone, RefCounted};
use std::ops::{Deref, DerefMut};

/// A wrapper for ref counted leptonica pointers that can be safely mutated.
///
/// For example if it is the only reference.
pub struct RefCountedExclusive<T: LeptonicaDestroy> {
    inner: T,
}

impl<T: LeptonicaDestroy> RefCountedExclusive<T> {
    /// Creates a new ref counted exclusive wrapper

    /// # Safety

    /// It must be safe for this wrapper to destroy (decrement the ref count).
    /// The ref count must have already been incremented before being passed to `new`.
    /// The pointer must not be mutated whilst this wrapper exists, except via this wrapper.
    pub unsafe fn new(inner: T) -> Self {
        Self { inner }
    }
}

impl<T: LeptonicaDestroy + LeptonicaClone> RefCountedExclusive<T> {
    /// Convert to a ref counted wrapper
    pub fn to_ref_counted(mut self) -> RefCounted<T> {
        unsafe { RefCounted::new(self.inner.clone()) }
    }
}

impl<T: LeptonicaDestroy> Drop for RefCountedExclusive<T> {
    fn drop(&mut self) {
        unsafe { self.inner.destroy() }
    }
}

impl<T: LeptonicaDestroy> Deref for RefCountedExclusive<T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        &self.inner
    }
}

impl<T: LeptonicaDestroy> DerefMut for RefCountedExclusive<T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.inner
    }
}