vendor/thread_local/src/unreachable.rs

   1 // Copyright 2017 Amanieu d'Antras
   2 //
   3 // Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
   4 // http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
   5 // http://opensource.org/licenses/MIT>, at your option. This file may not be
   6 // copied, modified, or distributed except according to those terms.
   7
   8 use std::hint::unreachable_unchecked;
   9
  10 /// An extension trait for `Option<T>` providing unchecked unwrapping methods.
  11 pub trait UncheckedOptionExt<T> {
  12     /// Get the value out of this Option without checking for None.
  13     unsafe fn unchecked_unwrap(self) -> T;
  14
  15     /// Assert that this Option is a None to the optimizer.
  16     unsafe fn unchecked_unwrap_none(self);
  17 }
  18
  19 /// An extension trait for `Result<T, E>` providing unchecked unwrapping methods.
  20 pub trait UncheckedResultExt<T, E> {
  21     /// Get the value out of this Result without checking for Err.
  22     unsafe fn unchecked_unwrap_ok(self) -> T;
  23
  24     /// Get the error out of this Result without checking for Ok.
  25     unsafe fn unchecked_unwrap_err(self) -> E;
  26 }
  27
  28 impl<T> UncheckedOptionExt<T> for Option<T> {
  29     unsafe fn unchecked_unwrap(self) -> T {
  30         match self {
  31             Some(x) => x,
  32             None => unreachable_unchecked(),
  33         }
  34     }
  35
  36     unsafe fn unchecked_unwrap_none(self) {
  37         if self.is_some() {
  38             unreachable_unchecked()
  39         }
  40     }
  41 }
  42
  43 impl<T, E> UncheckedResultExt<T, E> for Result<T, E> {
  44     unsafe fn unchecked_unwrap_ok(self) -> T {
  45         match self {
  46             Ok(x) => x,
  47             Err(_) => unreachable_unchecked(),
  48         }
  49     }
  50
  51     unsafe fn unchecked_unwrap_err(self) -> E {
  52         match self {
  53             Ok(_) => unreachable_unchecked(),
  54             Err(e) => e,
  55         }
  56     }
  57 }