vortex_zigzag/
compress.rs

1// SPDX-License-Identifier: Apache-2.0
2// SPDX-FileCopyrightText: Copyright the Vortex contributors
3
4use vortex_array::arrays::PrimitiveArray;
5use vortex_array::validity::Validity;
6use vortex_array::vtable::ValidityHelper;
7use vortex_buffer::BufferMut;
8use vortex_dtype::{NativePType, PType};
9use vortex_error::{VortexResult, vortex_bail};
10use zigzag::ZigZag as ExternalZigZag;
11
12use crate::ZigZagArray;
13
14pub fn zigzag_encode(parray: PrimitiveArray) -> VortexResult<ZigZagArray> {
15    let validity = parray.validity().clone();
16    let encoded = match parray.ptype() {
17        PType::I8 => zigzag_encode_primitive::<i8>(parray.into_buffer_mut(), validity),
18        PType::I16 => zigzag_encode_primitive::<i16>(parray.into_buffer_mut(), validity),
19        PType::I32 => zigzag_encode_primitive::<i32>(parray.into_buffer_mut(), validity),
20        PType::I64 => zigzag_encode_primitive::<i64>(parray.into_buffer_mut(), validity),
21        _ => vortex_bail!(
22            "ZigZag can only encode signed integers, got {}",
23            parray.ptype()
24        ),
25    };
26    ZigZagArray::try_new(encoded.to_array())
27}
28
29fn zigzag_encode_primitive<T: ExternalZigZag + NativePType>(
30    values: BufferMut<T>,
31    validity: Validity,
32) -> PrimitiveArray
33where
34    <T as ExternalZigZag>::UInt: NativePType,
35{
36    PrimitiveArray::new(values.map_each(|v| T::encode(v)).freeze(), validity)
37}
38
39pub fn zigzag_decode(parray: PrimitiveArray) -> VortexResult<PrimitiveArray> {
40    let validity = parray.validity().clone();
41    let decoded = match parray.ptype() {
42        PType::U8 => zigzag_decode_primitive::<i8>(parray.into_buffer_mut(), validity),
43        PType::U16 => zigzag_decode_primitive::<i16>(parray.into_buffer_mut(), validity),
44        PType::U32 => zigzag_decode_primitive::<i32>(parray.into_buffer_mut(), validity),
45        PType::U64 => zigzag_decode_primitive::<i64>(parray.into_buffer_mut(), validity),
46        _ => vortex_bail!(
47            "ZigZag can only decode unsigned integers, got {}",
48            parray.ptype()
49        ),
50    };
51    Ok(decoded)
52}
53
54fn zigzag_decode_primitive<T: ExternalZigZag + NativePType>(
55    values: BufferMut<T::UInt>,
56    validity: Validity,
57) -> PrimitiveArray
58where
59    <T as ExternalZigZag>::UInt: NativePType,
60{
61    PrimitiveArray::new(values.map_each(|v| T::decode(v)).freeze(), validity)
62}
63
64#[cfg(test)]
65mod test {
66    use vortex_array::ToCanonical;
67
68    use super::*;
69    use crate::ZigZagEncoding;
70
71    #[test]
72    fn test_compress_i8() {
73        let compressed = zigzag_encode(PrimitiveArray::from_iter(-100_i8..100)).unwrap();
74        assert_eq!(compressed.encoding_id(), ZigZagEncoding.id());
75        assert_eq!(
76            compressed.to_primitive().unwrap().as_slice::<i8>(),
77            (-100_i8..100).collect::<Vec<_>>()
78        );
79    }
80    #[test]
81    fn test_compress_i16() {
82        let compressed = zigzag_encode(PrimitiveArray::from_iter(-100_i16..100)).unwrap();
83        assert_eq!(compressed.encoding_id(), ZigZagEncoding.id());
84        assert_eq!(
85            compressed.to_primitive().unwrap().as_slice::<i16>(),
86            (-100_i16..100).collect::<Vec<_>>()
87        );
88    }
89    #[test]
90    fn test_compress_i32() {
91        let compressed = zigzag_encode(PrimitiveArray::from_iter(-100_i32..100)).unwrap();
92        assert_eq!(compressed.encoding_id(), ZigZagEncoding.id());
93        assert_eq!(
94            compressed.to_primitive().unwrap().as_slice::<i32>(),
95            (-100_i32..100).collect::<Vec<_>>()
96        );
97    }
98    #[test]
99    fn test_compress_i64() {
100        let compressed = zigzag_encode(PrimitiveArray::from_iter(-100_i64..100)).unwrap();
101        assert_eq!(compressed.encoding_id(), ZigZagEncoding.id());
102        assert_eq!(
103            compressed.to_primitive().unwrap().as_slice::<i64>(),
104            (-100_i64..100).collect::<Vec<_>>()
105        );
106    }
107}
vortex_zigzag/compress.rs

vortex_zigzag/
compress.rs
