1use std::io::{BufRead, Error, ErrorKind, Read, Result, Write};
3
4use crate::raw::{encode_multibyte_writer_skip_2, max_value, tag_prefix};
5use crate::{DecodeError, PrefixVarInt, MAX_1BYTE_TAG, MAX_LEN};
6
7impl From<DecodeError> for Error {
8 fn from(value: DecodeError) -> Self {
9 let kind = match value {
10 DecodeError::UnexpectedEob => ErrorKind::UnexpectedEof,
11 DecodeError::Overflow => ErrorKind::InvalidData,
12 };
13 Error::new(kind, value)
14 }
15}
16
17#[inline]
20pub fn write_prefix_varint<PV: PrefixVarInt>(v: PV, w: &mut impl Write) -> Result<usize> {
21 let v = v.to_prefix_varint_raw();
22 if v <= max_value(1) {
23 return w.write_all(&[v as u8]).map(|_| 1);
24 } else if v <= max_value(2) {
25 let tag_prefix = tag_prefix(2) >> 48;
26 let tagged = (v | tag_prefix) as u16;
27 return w.write_all(&tagged.to_be_bytes()).map(|_| 2);
28 }
29 encode_multibyte_writer_skip_2(v, w)
30}
31
32#[inline]
35pub fn read_prefix_varint<PV: PrefixVarInt>(r: &mut impl Read) -> Result<PV> {
36 let mut buf = [0u8; MAX_LEN];
37 r.read_exact(&mut buf[..1])?;
38 let tag = buf[0];
39 if tag <= MAX_1BYTE_TAG {
40 return PV::from_prefix_varint_raw(tag.into()).ok_or_else(|| DecodeError::Overflow.into());
41 }
42 let rem = tag.leading_ones() as usize;
43 r.read_exact(&mut buf[1..(1 + rem)])?;
44 PV::decode_prefix_varint(buf.as_slice())
45 .map(|(v, _)| v)
46 .map_err(|e| e.into())
47}
48
49#[inline]
51pub fn read_prefix_varint_buf<PV: PrefixVarInt>(r: &mut impl BufRead) -> Result<PV> {
52 let buf = r.fill_buf()?;
53 if buf.len() >= MAX_LEN {
54 let (v, len) = PV::decode_prefix_varint(buf).map_err(Error::from)?;
55 r.consume(len);
56 Ok(v)
57 } else {
58 read_prefix_varint(r)
59 }
60}