sark-http 0.28.5

HTTP wire types, semantics, codecs, and ownership invariants for Sark
Documentation 
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

use std::{mem, str};

pub(super) enum Utf8 {
    Ready,
    Two(u8),
    ThreeFirst(u8),
    ThreeSecond([u8; 2]),
    FourFirst(u8),
    FourSecond([u8; 2]),
    FourThird([u8; 3]),
}

impl Utf8 {
    pub(super) const fn new() -> Self {
        Self::Ready
    }

    pub(super) const fn is_ready(&self) -> bool {
        matches!(self, Self::Ready)
    }

    pub(super) fn push(&mut self, out: &mut [u8], written: &mut usize, byte: u8) {
        let state = mem::replace(self, Self::Ready);
        match state {
            Self::Ready => self.start(out, written, byte),
            Self::Two(first) => {
                if Self::is_tail(byte) {
                    Self::complete(out, written, [first, byte])
                } else {
                    self.restart(out, written, 1, byte)
                }
            }
            Self::ThreeFirst(first) => {
                if Self::is_tail(byte) {
                    *self = Self::ThreeSecond([first, byte]);
                } else {
                    self.restart(out, written, 1, byte)
                }
            }
            Self::ThreeSecond([first, second]) => {
                if Self::is_tail(byte) {
                    Self::complete(out, written, [first, second, byte])
                } else {
                    self.restart(out, written, 2, byte)
                }
            }
            Self::FourFirst(first) => {
                if Self::is_tail(byte) {
                    *self = Self::FourSecond([first, byte]);
                } else {
                    self.restart(out, written, 1, byte)
                }
            }
            Self::FourSecond([first, second]) => {
                if Self::is_tail(byte) {
                    *self = Self::FourThird([first, second, byte]);
                } else {
                    self.restart(out, written, 2, byte)
                }
            }
            Self::FourThird([first, second, third]) => {
                if Self::is_tail(byte) {
                    Self::complete(out, written, [first, second, third, byte])
                } else {
                    self.restart(out, written, 3, byte)
                }
            }
        }
    }

    pub(super) fn finish(self, out: &mut [u8], written: &mut usize) {
        let pending = match self {
            Self::Ready => 0,
            Self::Two(_) | Self::ThreeFirst(_) | Self::FourFirst(_) => 1,
            Self::ThreeSecond(_) | Self::FourSecond(_) => 2,
            Self::FourThird(_) => 3,
        };
        Self::reject(out, written, pending)
    }

    fn start(&mut self, out: &mut [u8], written: &mut usize, byte: u8) {
        match byte {
            byte if byte.is_ascii() => Self::emit(out, written, byte),
            0xc2..=0xdf => {
                *self = Self::Two(byte);
            }
            0xe0..=0xef => {
                *self = Self::ThreeFirst(byte);
            }
            0xf0..=0xf4 => {
                *self = Self::FourFirst(byte);
            }
            _ => Self::emit(out, written, b'?'),
        }
    }

    fn restart(&mut self, out: &mut [u8], written: &mut usize, len: usize, byte: u8) {
        Self::reject(out, written, len);
        self.start(out, written, byte)
    }

    fn complete<const N: usize>(out: &mut [u8], written: &mut usize, bytes: [u8; N]) {
        if str::from_utf8(&bytes).is_ok() {
            for byte in bytes {
                Self::emit(out, written, byte);
            }
        } else {
            Self::reject(out, written, N)
        }
    }

    fn reject(out: &mut [u8], written: &mut usize, len: usize) {
        for _ in 0..len {
            Self::emit(out, written, b'?');
        }
    }

    fn emit(out: &mut [u8], written: &mut usize, byte: u8) {
        // SAFETY: `Decoder::new` admitted a window that starts at or before the
        // read cursor, and at most one byte is emitted per consumed input byte,
        // so the write cursor never overtakes the read cursor and stays inside
        // that window.
        unsafe { *out.get_unchecked_mut(*written) = byte };
        *written += 1;
    }

    const fn is_tail(byte: u8) -> bool {
        matches!(byte, 0x80..=0xbf)
    }
}

const _: () = assert!(size_of::<Utf8>() <= 6);