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use std::ops::Deref;
use std::ops::DerefMut;

#[derive(Clone, Copy)]
pub struct ValueCache<T>{
    has_changed: bool,
    value: T,
}

impl<T> ValueCache<T>{
    #[inline]
    pub fn new(t: T) -> ValueCache<T>{
        ValueCache{
            has_changed: true,
            value: t
        }
    }

    #[inline]
    pub fn set(&mut self, t: T){
        self.has_changed = true;
        self.value = t;
    }

    #[inline]
    pub fn as_ref(&self) -> &T{
        &self.value
    }

    #[inline]
    pub fn as_mut(&mut self) -> &mut T{
        self.has_changed = true;
        &mut self.value
    }

    #[inline]
    pub fn has_changed(&self) -> bool{
        self.has_changed
    }

    #[inline]
    pub fn update(&mut self){
        self.has_changed = false;
    }
}

impl<T> Deref for ValueCache<T>{
    type Target = T;
    #[inline]
    fn deref(&self) -> &T{
        self.as_ref()
    }
}

impl<T> DerefMut for ValueCache<T>{
    #[inline]
    fn deref_mut(&mut self) -> &mut T{
        self.as_mut()
    }
}