azalea-block/src/lib.rs


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

mod behavior;
mod blocks;

pub use behavior::BlockBehavior;
pub use blocks::*;

use std::mem;

impl BlockState {
    /// Transmutes a u32 to a block state. UB if the value is not a valid block
    /// state.
    #[inline]
    pub unsafe fn from_u32_unsafe(state_id: u32) -> Self {
        mem::transmute::<u32, BlockState>(state_id)
    }

    #[inline]
    pub fn is_valid_state(state_id: u32) -> bool {
        state_id <= Self::max_state()
    }
}

impl TryFrom<u32> for BlockState {
    type Error = ();

    /// Safely converts a state id to a block state.
    fn try_from(state_id: u32) -> Result<Self, Self::Error> {
        if Self::is_valid_state(state_id) {
            Ok(unsafe { Self::from_u32_unsafe(state_id) })
        } else {
            Err(())
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_from_u32() {
        assert_eq!(BlockState::try_from(0).unwrap(), BlockState::Air);

        assert!(BlockState::try_from(BlockState::max_state()).is_ok());
        assert!(BlockState::try_from(BlockState::max_state() + 1).is_err());
    }
}