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

use parquet2::indexes::PageIndex;

use crate::{
    array::{Array, FixedSizeBinaryArray, MutableFixedSizeBinaryArray, PrimitiveArray},
    datatypes::{DataType, PhysicalType, PrimitiveType},
    trusted_len::TrustedLen,
};

use super::ColumnPageStatistics;

pub fn deserialize(indexes: &[PageIndex<Vec<u8>>], data_type: DataType) -> ColumnPageStatistics {
    ColumnPageStatistics {
        min: deserialize_binary_iter(
            indexes.iter().map(|index| index.min.as_ref()),
            data_type.clone(),
        ),
        max: deserialize_binary_iter(indexes.iter().map(|index| index.max.as_ref()), data_type),
        null_count: PrimitiveArray::from_trusted_len_iter(
            indexes
                .iter()
                .map(|index| index.null_count.map(|x| x as u64)),
        ),
    }
}

fn deserialize_binary_iter<'a, I: TrustedLen<Item = Option<&'a Vec<u8>>>>(
    iter: I,
    data_type: DataType,
) -> Box<dyn Array> {
    match data_type.to_physical_type() {
        PhysicalType::Primitive(PrimitiveType::Int128) => {
            Box::new(PrimitiveArray::from_trusted_len_iter(iter.map(|v| {
                v.map(|x| {
                    // Copy the fixed-size byte value to the start of a 16 byte stack
                    // allocated buffer, then use an arithmetic right shift to fill in
                    // MSBs, which accounts for leading 1's in negative (two's complement)
                    // values.
                    let n = x.len();
                    let mut bytes = [0u8; 16];
                    bytes[..n].copy_from_slice(x);
                    i128::from_be_bytes(bytes) >> (8 * (16 - n))
                })
            })))
        }
        _ => {
            let mut a = MutableFixedSizeBinaryArray::try_new(
                data_type,
                Vec::with_capacity(iter.size_hint().0),
                None,
            )
            .unwrap();
            for item in iter {
                a.push(item);
            }
            let a: FixedSizeBinaryArray = a.into();
            Box::new(a)
        }
    }
}