     1
     2
     3
     4
     5
     6
     7
     8
     9
    10
    11
    12
    13
    14
    15
    16
    17
    18
    19
    20
    21
    22
    23
    24
    25
    26
    27
    28
    29
    30
    31
    32
    33
    34
    35
    36
    37
    38
    39
    40
    41
    42
    43
    44
    45
    46
    47
    48
    49
    50
    51
    52
    53
    54
    55
    56
    57
    58
    59
    60
    61
    62
    63
    64
    65
    66
    67
    68
    69
    70
    71
    72
    73
    74

    // Copyright 2017 Amanieu d'Antras
    //
    // Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or
    // http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or
    // http://opensource.org/licenses/MIT>, at your option. This file may not be
    // copied, modified, or distributed except according to those terms.

    //! # unreachable
    //! inlined from https://github.com/reem/rust-unreachable/
    //!
    //! An unreachable code optimization hint in stable rust, and some useful
    //! extension traits for `Option` and `Result`.
    //!

    /// Hint to the optimizer that any code path which calls this function is
    /// statically unreachable and can be removed.
    ///
    /// Calling this function in reachable code invokes undefined behavior. Be
    /// very, very sure this is what you want; often, a simple `panic!` is more
    /// suitable.
    #[inline]
    pub unsafe fn unreachable() -> ! {
        /// The empty type for cases which can't occur.
        enum Void { }
        let x: &Void = ::std::mem::transmute(1usize);
        match *x {}
    }

    /// An extension trait for `Option<T>` providing unchecked unwrapping methods.
    pub trait UncheckedOptionExt<T> {
        /// Get the value out of this Option without checking for None.
        unsafe fn unchecked_unwrap(self) -> T;

        /// Assert that this Option is a None to the optimizer.
        unsafe fn unchecked_unwrap_none(self);
    }

    /// An extension trait for `Result<T, E>` providing unchecked unwrapping methods.
    pub trait UncheckedResultExt<T, E> {
        /// Get the value out of this Result without checking for Err.
        unsafe fn unchecked_unwrap_ok(self) -> T;

        /// Get the error out of this Result without checking for Ok.
        unsafe fn unchecked_unwrap_err(self) -> E;
    }

    impl<T> UncheckedOptionExt<T> for Option<T> {
        unsafe fn unchecked_unwrap(self) -> T {
            match self {
                Some(x) => x,
                None => unreachable()
            }
        }

        unsafe fn unchecked_unwrap_none(self) {
            if self.is_some() { unreachable() }
        }
    }

    impl<T, E> UncheckedResultExt<T, E> for Result<T, E> {
        unsafe fn unchecked_unwrap_ok(self) -> T {
            match self {
                Ok(x) => x,
                Err(_) => unreachable()
            }
        }

        unsafe fn unchecked_unwrap_err(self) -> E {
            match self {
                Ok(_) => unreachable(),
                Err(e) => e
            }
        }
    }

# Help

## Keyboard Shortcuts

`?`
  Show this help dialog
`S`
  Focus the search field
`↑`
  Move up in search results
`↓`
  Move down in search results
`↹`
  Switch tab
`⏎`
  Go to active search result
`+`
  Expand all sections
`-`
  Collapse all sections

## Search Tricks

Prefix searches with a type followed by a colon (e.g., `fn:`) to restrict the search to a given type.

Accepted types are: `fn`, `mod`, `struct`, `enum`, `trait`, `type`, `macro`, and `const`.

Search functions by type signature (e.g., `vec -> usize` or `* -> vec`)

Search multiple things at once by splitting your query with comma (e.g., `str,u8` or `String,struct:Vec,test`)