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

use super::bindings::Gl2;

macro_rules! error_variants {
    ($iv:vis $st:ident { $($v:ident($c:expr) -> $s:literal),+ }) => {
        #[repr(u32)]
        #[derive(Debug)]
        $iv enum $st {
            $($v = $c),+
        }
        impl From<u32> for $st {
            fn from(v: u32) -> Self {
                match v {
                    $(x if x == $st::$v as u32 => $st::$v),+,
                    _ => $st::UnknownError,
                }
            }
        }
        impl std::fmt::Display for $st {
            fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
                write!(f, "{}", match self {
                    $($st::$v => $s),+
                })
            }
        }
    };
}

error_variants!(pub WebGl2Error {
    ContextLost(Gl2::CONTEXT_LOST_WEBGL) -> "lost webgl context",
    InvalidEnum(Gl2::INVALID_ENUM) -> "invalid enum",
    InvalidValue(Gl2::INVALID_VALUE) -> "invalid value",
    InvalidOperation(Gl2::INVALID_OPERATION) -> "invalid operation",
    InvalidFramebufferOperation(Gl2::INVALID_FRAMEBUFFER_OPERATION) -> "invalid framebuffer operation",
    OutOfMemory(Gl2::OUT_OF_MEMORY) -> "out of memory",
    UnknownError(0xff) -> "unknown webgl2 error"
});

#[cfg(test)]
mod tests {
    use super::*;
    macro_rules! assert_enum {
        ($a:expr, $b:expr) => {
            assert_eq!(std::mem::discriminant(&$a), std::mem::discriminant(&$b));
        };
    }

    #[test]
    fn from() {
        assert_enum!(WebGl2Error::ContextLost, Gl2::CONTEXT_LOST_WEBGL.into());
        assert_enum!(WebGl2Error::InvalidEnum, Gl2::INVALID_ENUM.into());
        assert_enum!(WebGl2Error::InvalidValue, Gl2::INVALID_VALUE.into());
        assert_enum!(WebGl2Error::InvalidOperation, Gl2::INVALID_OPERATION.into());
        assert_enum!(
            WebGl2Error::InvalidFramebufferOperation,
            Gl2::INVALID_FRAMEBUFFER_OPERATION.into()
        );
        assert_enum!(WebGl2Error::OutOfMemory, Gl2::OUT_OF_MEMORY.into());
        assert_enum!(WebGl2Error::UnknownError, 0xff.into());
        assert_enum!(WebGl2Error::UnknownError, 0xdff.into());
        assert_enum!(WebGl2Error::UnknownError, 0.into());
    }
}