unsigned_varint/
io.rs

1// Copyright 2020 Parity Technologies (UK) Ltd.
2//
3// Permission is hereby granted, free of charge, to any person obtaining a copy of
4// this software and associated documentation files (the "Software"), to deal in
5// the Software without restriction, including without limitation the rights to
6// use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
7// the Software, and to permit persons to whom the Software is furnished to do so,
8// subject to the following conditions:
9//
10// The above copyright notice and this permission notice shall be included in all
11// copies or substantial portions of the Software.
12//
13// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
15// FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS
16// OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
17// WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
18// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
19
20//! Decode using [`std::io::Read`] types.
21
22use crate::{decode, encode};
23use std::{fmt, io};
24
25macro_rules! gen {
26    ($($name:ident, $d:expr, $t:ident, $b:ident);*) => {
27        $(
28            #[doc = " Try to read and decode a "]
29            #[doc = $d]
30            #[doc = " from the given `Read` type."]
31            pub fn $name<R: io::Read>(mut reader: R) -> Result<$t, ReadError> {
32                let mut b = encode::$b();
33                for i in 0 .. b.len() {
34                    let n = reader.read(&mut b[i .. i + 1])?;
35                    if n == 0 {
36                        return Err(ReadError::Io(io::ErrorKind::UnexpectedEof.into()))
37                    }
38                    if decode::is_last(b[i]) {
39                        return Ok(decode::$t(&b[..= i])?.0)
40                    }
41                }
42                Err(decode::Error::Overflow.into())
43            }
44        )*
45    }
46}
47
48gen! {
49    read_u8,    "`u8`",    u8,    u8_buffer;
50    read_u16,   "`u16`",   u16,   u16_buffer;
51    read_u32,   "`u32`",   u32,   u32_buffer;
52    read_u64,   "`u64`",   u64,   u64_buffer;
53    read_u128,  "`u128`",  u128,  u128_buffer;
54    read_usize, "`usize`", usize, usize_buffer
55}
56
57/// Possible read errors.
58#[non_exhaustive]
59#[derive(Debug)]
60pub enum ReadError {
61    Io(io::Error),
62    Decode(decode::Error)
63}
64
65impl fmt::Display for ReadError {
66    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
67        match self {
68            ReadError::Io(e) => write!(f, "i/o error: {}", e),
69            ReadError::Decode(e) => write!(f, "decode error: {}", e)
70        }
71    }
72}
73
74impl std::error::Error for ReadError {
75    fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
76        if let ReadError::Io(e) = self {
77            Some(e)
78        } else {
79            None
80        }
81    }
82}
83
84impl From<io::Error> for ReadError {
85    fn from(e: io::Error) -> Self {
86        ReadError::Io(e)
87    }
88}
89
90impl From<decode::Error> for ReadError {
91    fn from(e: decode::Error) -> Self {
92        ReadError::Decode(e)
93    }
94}
95
96impl Into<io::Error> for ReadError {
97    fn into(self) -> io::Error {
98        match self {
99            ReadError::Io(e) => e,
100            ReadError::Decode(e) => e.into(),
101        }
102    }
103}
unsigned_varint/io.rs

unsigned_varint/
io.rs
