hts 0.1.17

Rust binding for htslib
Documentation 
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use std::cell::RefCell;
use std::ops::{Deref, DerefMut};
use std::ptr::NonNull;

/// An object that can be handled by the memory pool
pub trait MemoryPoolObject {
    /// Allocate a new object
    fn alloc() -> Option<NonNull<Self>>;
    /// Deallocate a object
    fn dealloc(obj: NonNull<Self>);
}

/// The smart pointer for an object that allocated by memory pool
pub struct PooledObject<'a, T: MemoryPoolObject> {
    inner: NonNull<T>,
    allocator: &'a MemoryPool<T>,
}

impl<'a, T: MemoryPoolObject> Deref for PooledObject<'a, T> {
    type Target = T;
    fn deref(&self) -> &Self::Target {
        unsafe { self.inner.as_ref() }
    }
}

impl<'a, T: MemoryPoolObject> DerefMut for PooledObject<'a, T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        unsafe { self.inner.as_mut() }
    }
}

impl<'a, T: MemoryPoolObject> Drop for PooledObject<'a, T> {
    fn drop(&mut self) {
        let pool = self.allocator;
        if pool.free_list.borrow().len() + 1 >= pool.free_list_limit {
            T::dealloc(self.inner);
        } else {
            let mut free_list = pool.free_list.borrow_mut();
            free_list.push(self.inner);
        }
        self.inner = NonNull::dangling();
    }
}

pub struct MemoryPool<T: MemoryPoolObject> {
    free_list: RefCell<Vec<NonNull<T>>>,
    free_list_limit: usize,
}

impl<T: MemoryPoolObject> Drop for MemoryPool<T> {
    fn drop(&mut self) {
        for cached_obj in self.free_list.take() {
            T::dealloc(cached_obj);
        }
    }
}

impl<T: MemoryPoolObject> MemoryPool<T> {
    pub fn with_capacity(_size: usize) -> Self {
        Self {
            free_list: RefCell::new(Vec::new()),
            free_list_limit: 0,
        }
    }

    pub fn alloc_obj(&self) -> Option<PooledObject<T>> {
        if self.free_list.borrow().len() > 0 {
            let mut free_list = self.free_list.borrow_mut();
            Some(PooledObject {
                inner: free_list.pop().unwrap(),
                allocator: self,
            })
        } else {
            Some(PooledObject {
                inner: T::alloc()?,
                allocator: self,
            })
        }
    }
}