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use std::ops::Deref;

/// This crate provides the `Final`, struct which guarantees the interior
/// immutability of the value that it wraps. This is useful for
/// preserving invariants on the fields of structures, whose 'safe'
/// mutation would cause undefined behavior.

// https://www.reddit.com/r/rust/comments/26jzm5/immutable_struct_members_in_rust/chs3ljz/

/// Wraps a value in the `Final` type, which does not give out mutable
/// references.
#[derive(Debug)]
pub struct Final<T>(T);

impl<T> Final<T> {
  /// Wrap a value `v` in a `Final`
  #[inline]
  pub fn new(v: T) -> Final<T> {
    Final(v)
  }
}

impl<T> Deref for Final<T> {
  type Target = T;

  fn deref(&self) -> &T {
    &self.0
  }
}