      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
     75
     76
     77
     78
     79
     80
     81
     82
     83
     84
     85
     86
     87
     88
     89
     90
     91
     92
     93
     94
     95
     96
     97
     98
     99
    100
    101
    102
    103
    104
    105
    106
    107
    108
    109
    110
    111
    112
    113
    114
    115
    116
    117
    118
    119
    120
    121
    122
    123
    124
    125
    126
    127
    128
    129
    130
    131
    132
    133
    134
    135
    136
    137
    138
    139
    140
    141
    142
    143
    144
    145
    146
    147
    148
    149
    150
    151
    152
    153
    154
    155
    156
    157
    158
    159
    160

    //! Buffer management for same-process client<->server communication.

    use std::io::{self, Write};
    use std::mem;
    use std::ops::{Deref, DerefMut};
    use std::slice;

    #[repr(C)]
    struct Slice<'a, T: 'a> {
        data: &'a [T; 0],
        len: usize,
    }

    unsafe impl<'a, T: Sync> Sync for Slice<'a, T> {}
    unsafe impl<'a, T: Sync> Send for Slice<'a, T> {}

    impl<T> Copy for Slice<'a, T> {}
    impl<T> Clone for Slice<'a, T> {
        fn clone(&self) -> Self {
            *self
        }
    }

    impl<T> From<&'a [T]> for Slice<'a, T> {
        fn from(xs: &'a [T]) -> Self {
            Slice {
                data: unsafe { &*(xs.as_ptr() as *const [T; 0]) },
                len: xs.len(),
            }
        }
    }

    impl<T> Deref for Slice<'a, T> {
        type Target = [T];
        fn deref(&self) -> &[T] {
            unsafe { slice::from_raw_parts(self.data.as_ptr(), self.len) }
        }
    }

    #[repr(C)]
    pub struct Buffer<T: Copy> {
        data: *mut T,
        len: usize,
        capacity: usize,
        extend_from_slice: extern "C" fn(Buffer<T>, Slice<T>) -> Buffer<T>,
        drop: extern "C" fn(Buffer<T>),
    }

    unsafe impl<T: Copy + Sync> Sync for Buffer<T> {}
    unsafe impl<T: Copy + Send> Send for Buffer<T> {}

    impl<T: Copy> Default for Buffer<T> {
        fn default() -> Self {
            Self::from(vec![])
        }
    }

    impl<T: Copy> Deref for Buffer<T> {
        type Target = [T];
        fn deref(&self) -> &[T] {
            unsafe { slice::from_raw_parts(self.data as *const T, self.len) }
        }
    }

    impl<T: Copy> DerefMut for Buffer<T> {
        fn deref_mut(&mut self) -> &mut [T] {
            unsafe { slice::from_raw_parts_mut(self.data, self.len) }
        }
    }

    impl<T: Copy> Buffer<T> {
        pub(super) fn new() -> Self {
            Self::default()
        }

        pub(super) fn clear(&mut self) {
            self.len = 0;
        }

        pub(super) fn take(&mut self) -> Self {
            mem::replace(self, Self::default())
        }

        pub(super) fn extend_from_slice(&mut self, xs: &[T]) {
            // Fast path to avoid going through an FFI call.
            if let Some(final_len) = self.len.checked_add(xs.len()) {
                if final_len <= self.capacity {
                    let dst = unsafe { slice::from_raw_parts_mut(self.data, self.capacity) };
                    dst[self.len..][..xs.len()].copy_from_slice(xs);
                    self.len = final_len;
                    return;
                }
            }
            let b = self.take();
            *self = (b.extend_from_slice)(b, Slice::from(xs));
        }
    }

    impl Write for Buffer<u8> {
        fn write(&mut self, xs: &[u8]) -> io::Result<usize> {
            self.extend_from_slice(xs);
            Ok(xs.len())
        }

        fn write_all(&mut self, xs: &[u8]) -> io::Result<()> {
            self.extend_from_slice(xs);
            Ok(())
        }

        fn flush(&mut self) -> io::Result<()> {
            Ok(())
        }
    }

    impl<T: Copy> Drop for Buffer<T> {
        fn drop(&mut self) {
            let b = self.take();
            (b.drop)(b);
        }
    }

    impl<T: Copy> From<Vec<T>> for Buffer<T> {
        fn from(mut v: Vec<T>) -> Self {
            let (data, len, capacity) = (v.as_mut_ptr(), v.len(), v.capacity());
            mem::forget(v);

            // This utility function is nested in here because it can *only*
            // be safely called on `Buffer`s created by *this* `proc_macro`.
            fn to_vec<T: Copy>(b: Buffer<T>) -> Vec<T> {
                unsafe {
                    let Buffer {
                        data,
                        len,
                        capacity,
                        ..
                    } = b;
                    mem::forget(b);
                    Vec::from_raw_parts(data, len, capacity)
                }
            }

            extern "C" fn extend_from_slice<T: Copy>(b: Buffer<T>, xs: Slice<T>) -> Buffer<T> {
                let mut v = to_vec(b);
                v.extend_from_slice(&xs);
                Buffer::from(v)
            }

            extern "C" fn drop<T: Copy>(b: Buffer<T>) {
                mem::drop(to_vec(b));
            }

            Buffer {
                data,
                len,
                capacity,
                extend_from_slice,
                drop,
            }
        }
    }

# 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`)