azalea_block/
block_state.rs

1use std::{
2    fmt::{self, Debug},
3    io::{self, Cursor, Write},
4};
5
6use azalea_buf::{AzaleaRead, AzaleaReadVar, AzaleaWrite, AzaleaWriteVar, BufReadError};
7
8use crate::Block;
9
10/// The type that's used internally to represent a block state ID.
11///
12/// This should be either `u16` or `u32`. If you choose to modify it, you must
13/// also change it in `azalea-block-macros/src/lib.rs`.
14///
15/// This does not affect protocol serialization, it just allows you to make the
16/// internal type smaller if you want.
17pub type BlockStateIntegerRepr = u16;
18
19/// A representation of a state a block can be in.
20///
21/// For example, a stone block only has one state but each possible stair
22/// rotation is a different state.
23///
24/// Note that this type is internally either a `u16` or `u32`, depending on
25/// [`BlockStateIntegerRepr`].
26#[derive(Copy, Clone, PartialEq, Eq, Default, Hash)]
27pub struct BlockState {
28    /// The protocol ID for the block state. IDs may change every
29    /// version, so you shouldn't hard-code them or store them in databases.
30    id: BlockStateIntegerRepr,
31}
32
33impl BlockState {
34    /// A shortcut for getting the air block state, since it always has an ID of
35    /// 0.
36    pub const AIR: BlockState = BlockState { id: 0 };
37
38    /// Create a new BlockState and panic if the block is not a valid state.
39    ///
40    /// You should probably use [`BlockState::try_from`] instead.
41    #[inline]
42    pub(crate) const fn new_const(id: BlockStateIntegerRepr) -> Self {
43        assert!(Self::is_valid_state(id));
44        Self { id }
45    }
46
47    /// Whether the block state is possible to exist in vanilla Minecraft.
48    ///
49    /// It's equivalent to checking that the state ID is not greater than
50    /// [`Self::MAX_STATE`].
51    #[inline]
52    pub const fn is_valid_state(state_id: BlockStateIntegerRepr) -> bool {
53        state_id <= Self::MAX_STATE
54    }
55
56    /// Returns true if the block is air. This only checks for normal air, not
57    /// other types like cave air.
58    #[inline]
59    pub fn is_air(&self) -> bool {
60        self == &Self::AIR
61    }
62
63    /// Returns the protocol ID for the block state. IDs may change every
64    /// version, so you shouldn't hard-code them or store them in databases.
65    #[inline]
66    pub const fn id(&self) -> BlockStateIntegerRepr {
67        self.id
68    }
69}
70
71impl TryFrom<u32> for BlockState {
72    type Error = ();
73
74    /// Safely converts a u32 state id to a block state.
75    fn try_from(state_id: u32) -> Result<Self, Self::Error> {
76        let state_id = state_id as BlockStateIntegerRepr;
77        if Self::is_valid_state(state_id) {
78            Ok(BlockState { id: state_id })
79        } else {
80            Err(())
81        }
82    }
83}
84impl TryFrom<u16> for BlockState {
85    type Error = ();
86
87    /// Safely converts a u16 state id to a block state.
88    fn try_from(state_id: u16) -> Result<Self, Self::Error> {
89        let state_id = state_id as BlockStateIntegerRepr;
90        if Self::is_valid_state(state_id) {
91            Ok(BlockState { id: state_id })
92        } else {
93            Err(())
94        }
95    }
96}
97
98impl AzaleaRead for BlockState {
99    fn azalea_read(buf: &mut Cursor<&[u8]>) -> Result<Self, BufReadError> {
100        let state_id = u32::azalea_read_var(buf)?;
101        Self::try_from(state_id).map_err(|_| BufReadError::UnexpectedEnumVariant {
102            id: state_id as i32,
103        })
104    }
105}
106impl AzaleaWrite for BlockState {
107    fn azalea_write(&self, buf: &mut impl Write) -> io::Result<()> {
108        u32::azalea_write_var(&(self.id as u32), buf)
109    }
110}
111
112impl Debug for BlockState {
113    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
114        write!(
115            f,
116            "BlockState(id: {}, {:?})",
117            self.id,
118            Box::<dyn Block>::from(*self)
119        )
120    }
121}
122
123impl From<BlockState> for azalea_registry::Block {
124    fn from(value: BlockState) -> Self {
125        Box::<dyn Block>::from(value).as_registry_block()
126    }
127}
128
129#[cfg(test)]
130mod tests {
131    use super::*;
132
133    #[test]
134    fn test_from_u32() {
135        assert_eq!(
136            BlockState::try_from(0 as BlockStateIntegerRepr).unwrap(),
137            BlockState::AIR
138        );
139
140        assert!(BlockState::try_from(BlockState::MAX_STATE).is_ok());
141        assert!(BlockState::try_from(BlockState::MAX_STATE + 1).is_err());
142    }
143
144    #[test]
145    fn test_from_blockstate() {
146        let block: Box<dyn Block> = Box::<dyn Block>::from(BlockState::AIR);
147        assert_eq!(block.id(), "air");
148
149        let block: Box<dyn Block> =
150            Box::<dyn Block>::from(BlockState::from(azalea_registry::Block::FloweringAzalea));
151        assert_eq!(block.id(), "flowering_azalea");
152    }
153
154    #[test]
155    fn test_debug_blockstate() {
156        let formatted = format!(
157            "{:?}",
158            BlockState::from(azalea_registry::Block::FloweringAzalea)
159        );
160        assert!(formatted.ends_with(", FloweringAzalea)"), "{}", formatted);
161
162        let formatted = format!(
163            "{:?}",
164            BlockState::from(azalea_registry::Block::BigDripleafStem)
165        );
166        assert!(
167            formatted.ends_with(", BigDripleafStem { facing: North, waterlogged: false })"),
168            "{}",
169            formatted
170        );
171    }
172}
azalea_block/block_state.rs

azalea_block/
block_state.rs
