windows_strings/
literals.rs

1/// A literal UTF-8 string with a trailing null terminator.
2#[macro_export]
3macro_rules! s {
4    ($s:literal) => {
5        $crate::PCSTR::from_raw(::core::concat!($s, '\0').as_ptr())
6    };
7}
8
9/// A literal UTF-16 wide string with a trailing null terminator.
10#[macro_export]
11macro_rules! w {
12    ($s:literal) => {{
13        const INPUT: &[u8] = $s.as_bytes();
14        const OUTPUT_LEN: usize = $crate::utf16_len(INPUT) + 1;
15        const OUTPUT: &[u16; OUTPUT_LEN] = {
16            let mut buffer = [0; OUTPUT_LEN];
17            let mut input_pos = 0;
18            let mut output_pos = 0;
19            while let Some((mut code_point, new_pos)) = $crate::decode_utf8_char(INPUT, input_pos) {
20                input_pos = new_pos;
21                if code_point <= 0xffff {
22                    buffer[output_pos] = code_point as u16;
23                    output_pos += 1;
24                } else {
25                    code_point -= 0x10000;
26                    buffer[output_pos] = 0xd800 + (code_point >> 10) as u16;
27                    output_pos += 1;
28                    buffer[output_pos] = 0xdc00 + (code_point & 0x3ff) as u16;
29                    output_pos += 1;
30                }
31            }
32            &{ buffer }
33        };
34        $crate::PCWSTR::from_raw(OUTPUT.as_ptr())
35    }};
36}
37
38/// A literal HSTRING, length-prefixed wide string with a trailing null terminator.
39#[macro_export]
40macro_rules! h {
41    ($s:literal) => {{
42        const INPUT: &[u8] = $s.as_bytes();
43        const OUTPUT_LEN: usize = $crate::utf16_len(INPUT) + 1;
44        static RESULT: $crate::HSTRING = {
45            if OUTPUT_LEN == 1 {
46                unsafe { ::core::mem::transmute(::core::ptr::null::<u16>()) }
47            } else {
48                #[repr(C)]
49                struct HSTRING_HEADER {
50                    flags: u32,
51                    len: u32,
52                    padding1: u32,
53                    padding2: u32,
54                    ptr: *const u16,
55                    padding3: i32,
56                    padding4: u16,
57                }
58                const OUTPUT: $crate::PCWSTR = $crate::w!($s);
59                const HEADER: HSTRING_HEADER = HSTRING_HEADER {
60                    flags: 0x11,
61                    len: (OUTPUT_LEN - 1) as u32,
62                    padding1: 0,
63                    padding2: 0,
64                    ptr: OUTPUT.as_ptr(),
65                    padding3: 0,
66                    padding4: 0,
67                };
68                // SAFETY: an `HSTRING` is exactly equivalent to a pointer to an `HSTRING_HEADER`
69                unsafe { ::core::mem::transmute::<&HSTRING_HEADER, $crate::HSTRING>(&HEADER) }
70            }
71        };
72        &RESULT
73    }};
74}
75
76#[doc(hidden)]
77pub const fn decode_utf8_char(bytes: &[u8], mut pos: usize) -> Option<(u32, usize)> {
78    if bytes.len() == pos {
79        return None;
80    }
81    let ch = bytes[pos] as u32;
82    pos += 1;
83    if ch <= 0x7f {
84        return Some((ch, pos));
85    }
86    if (ch & 0xe0) == 0xc0 {
87        if bytes.len() - pos < 1 {
88            return None;
89        }
90        let ch2 = bytes[pos] as u32;
91        pos += 1;
92        if (ch2 & 0xc0) != 0x80 {
93            return None;
94        }
95        let result: u32 = ((ch & 0x1f) << 6) | (ch2 & 0x3f);
96        if result <= 0x7f {
97            return None;
98        }
99        return Some((result, pos));
100    }
101    if (ch & 0xf0) == 0xe0 {
102        if bytes.len() - pos < 2 {
103            return None;
104        }
105        let ch2 = bytes[pos] as u32;
106        pos += 1;
107        let ch3 = bytes[pos] as u32;
108        pos += 1;
109        if (ch2 & 0xc0) != 0x80 || (ch3 & 0xc0) != 0x80 {
110            return None;
111        }
112        let result = ((ch & 0x0f) << 12) | ((ch2 & 0x3f) << 6) | (ch3 & 0x3f);
113        if result <= 0x7ff || (0xd800 <= result && result <= 0xdfff) {
114            return None;
115        }
116        return Some((result, pos));
117    }
118    if (ch & 0xf8) == 0xf0 {
119        if bytes.len() - pos < 3 {
120            return None;
121        }
122        let ch2 = bytes[pos] as u32;
123        pos += 1;
124        let ch3 = bytes[pos] as u32;
125        pos += 1;
126        let ch4 = bytes[pos] as u32;
127        pos += 1;
128        if (ch2 & 0xc0) != 0x80 || (ch3 & 0xc0) != 0x80 || (ch4 & 0xc0) != 0x80 {
129            return None;
130        }
131        let result =
132            ((ch & 0x07) << 18) | ((ch2 & 0x3f) << 12) | ((ch3 & 0x3f) << 6) | (ch4 & 0x3f);
133        if result <= 0xffff || 0x10ffff < result {
134            return None;
135        }
136        return Some((result, pos));
137    }
138    None
139}
140
141#[doc(hidden)]
142pub const fn utf16_len(bytes: &[u8]) -> usize {
143    let mut pos = 0;
144    let mut len = 0;
145    while let Some((code_point, new_pos)) = decode_utf8_char(bytes, pos) {
146        pos = new_pos;
147        len += if code_point <= 0xffff { 1 } else { 2 };
148    }
149    len
150}
151
152#[cfg(test)]
153mod tests {
154    use super::*;
155
156    #[test]
157    fn test() {
158        assert_eq!(decode_utf8_char(b"123", 0), Some((0x31, 1)));
159        assert_eq!(decode_utf8_char(b"123", 1), Some((0x32, 2)));
160        assert_eq!(decode_utf8_char(b"123", 2), Some((0x33, 3)));
161        assert_eq!(decode_utf8_char(b"123", 3), None);
162        assert_eq!(utf16_len(b"123"), 3);
163        assert_eq!(utf16_len("α & ω".as_bytes()), 5);
164    }
165}
windows_strings/literals.rs

windows_strings/
literals.rs
