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

use {
    std::fmt,
    std::slice,
    crate::shader_ast::Ident
};

#[derive(Clone, Debug)]
pub struct Swizzle {
    indices: Vec<usize>,
}

#[allow(clippy::len_without_is_empty)]
impl Swizzle {
    pub fn parse(ident: Ident) -> Option<Swizzle> {
        let mut indices = Vec::new();
        ident.to_id().as_string(|string| {
            let mut chars = string.unwrap().chars();
            let mut ch = chars.next().unwrap();
            match ch {
                'x' | 'y' | 'z' | 'w' => loop {
                    indices.push(match ch {
                        'x' => 0,
                        'y' => 1,
                        'z' => 2,
                        'w' => 3,
                        _ => return None,
                    });
                    ch = match chars.next() {
                        Some(ch) => ch,
                        None => break,
                    };
                },
                'r' | 'g' | 'b' | 'a' => loop {
                    indices.push(match ch {
                        'r' => 0,
                        'g' => 1,
                        'b' => 2,
                        'a' => 3,
                        _ => return None,
                    });
                    ch = match chars.next() {
                        Some(ch) => ch,
                        None => break,
                    };
                },
                _ => return None,
            }
            Some(Swizzle { indices })
        })
    }

    pub fn from_range(start: usize, end: usize) -> Swizzle {
        let mut indices = Vec::new();
        for index in start..end {
            indices.push(index)
        }
        Swizzle { indices }
    }

    pub fn len(&self) -> usize {
        self.indices.len()
    }

    pub fn iter(&self) -> Iter {
        Iter(self.indices.iter())
    }
}

impl fmt::Display for Swizzle {
    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
        for index in &self.indices {
            write!(
                f,
                "{}",
                match index {
                    0 => "x",
                    1 => "y",
                    2 => "z",
                    3 => "w",
                    _ => panic!(),
                }
            )?;
        }
        Ok(())
    }
}
impl<'a> IntoIterator for &'a Swizzle {
    type Item = &'a usize;
    type IntoIter = Iter<'a>;

    fn into_iter(self) -> Iter<'a> {
        self.iter()
    }
}

pub struct Iter<'a>(slice::Iter<'a, usize>);

impl<'a> Iterator for Iter<'a> {
    type Item = &'a usize;

    fn next(&mut self) -> Option<&'a usize> {
        self.0.next()
    }
}