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#[derive(Copy, Clone, PartialEq, PartialOrd)]
struct CacheTableEntry<T: Copy + Clone + PartialEq + PartialOrd> {
hash: u64,
entry: T
}
pub struct CacheTable<T: Copy + Clone + PartialEq + PartialOrd> {
table: Box<[CacheTableEntry<T>]>,
mask: usize
}
impl <T: Copy + Clone + PartialEq + PartialOrd> CacheTable<T> {
pub fn new(size: usize, default: T) -> CacheTable<T> {
if size.count_ones() != 1 {
panic!("You cannot create a CacheTable with a non-binary number.");
}
let values = vec![CacheTableEntry { hash: 0, entry: default }; size];
CacheTable {
table: values.into_boxed_slice(),
mask: size - 1
}
}
pub fn get(&self, hash: u64) -> Option<T> {
let entry = unsafe { *self.table.get_unchecked((hash as usize) & self.mask) };
if entry.hash == hash {
Some(entry.entry)
} else {
None
}
}
pub fn add(&mut self, hash: u64, entry: T) {
let mut e = unsafe { self.table.get_unchecked_mut((hash as usize) & self.mask) };
*e = CacheTableEntry { hash: hash, entry: entry };
}
}