1// Take a look at the license at the top of the repository in the LICENSE file.
2
3use crate::json::read::internal_reader::InternalReader;
4use std::{
5 error, fmt,
6 io::{Error, Read},
7 str::from_utf8,
8};
9
10pub struct ByteToChar<R> {
11 iter: InternalReader<R>,
12}
13
14impl<R: Read> ByteToChar<R> {
15 #[inline]
16 pub fn new(read: R, buffer_size: usize) -> Result<Self, Error> {
17 Ok(ByteToChar {
18 iter: InternalReader::new(read, buffer_size)?,
19 })
20 }
21
22 fn get_next(&mut self) -> Result<Option<u8>, CharsError> {
23 match self.iter.next() {
24 None => Ok(None),
25 Some(item: Result) => match item {
26 Ok(item: u8) => Ok(Some(item)),
27 Err(err: Error) => Err(CharsError::Other(err)),
28 },
29 }
30 }
31}
32
33impl<R: Read + fmt::Debug> fmt::Debug for ByteToChar<R> {
34 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
35 f.debug_struct("Filter").field(name:"iter", &self.iter).finish()
36 }
37}
38
39impl<R: Read> Iterator for ByteToChar<R> {
40 type Item = Result<char, CharsError>;
41
42 fn next(&mut self) -> Option<Result<char, CharsError>> {
43 let first_byte = match self.get_next() {
44 Err(err) => return Some(Err(err)),
45 Ok(item) => item?,
46 };
47
48 let width = utf8_char_width(first_byte);
49 if width == 1 {
50 return Some(Ok(first_byte as char));
51 }
52 if width == 0 {
53 return Some(Err(CharsError::NotUtf8));
54 }
55 let mut buf = [first_byte, 0, 0, 0];
56 {
57 let mut start = 1;
58 while start < width {
59 let byte = match self.get_next() {
60 Err(err) => return Some(Err(err)),
61 Ok(item) => match item {
62 Some(item) => item,
63 None => return Some(Err(CharsError::NotUtf8)),
64 },
65 };
66 buf[start] = byte;
67 start += 1;
68 }
69 }
70 Some(match from_utf8(&buf[..width]).ok() {
71 Some(s) => Ok(s.chars().next().unwrap()),
72 None => Err(CharsError::NotUtf8),
73 })
74 }
75}
76
77fn utf8_char_width(b: u8) -> usize {
78 UTF8_CHAR_WIDTH[b as usize] as usize
79}
80
81// https://tools.ietf.org/html/rfc3629
82static UTF8_CHAR_WIDTH: [u8; 256] = [
83 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
84 1, // 0x1F
85 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
86 1, // 0x3F
87 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
88 1, // 0x5F
89 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
90 1, // 0x7F
91 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
92 0, // 0x9F
93 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
94 0, // 0xBF
95 0, 0, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
96 2, // 0xDF
97 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, // 0xEF
98 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0xFF
99];
100
101/// An enumeration of possible errors that can be generated from the `Chars`
102/// adapter.
103#[derive(Debug)]
104pub enum CharsError {
105 /// Variant representing that the underlying stream was read successfully
106 /// but it did not contain valid utf8 data.
107 NotUtf8,
108
109 /// Variant representing that an I/O error occurred.
110 Other(Error),
111}
112
113impl error::Error for CharsError {
114 fn cause(&self) -> Option<&dyn error::Error> {
115 match *self {
116 CharsError::NotUtf8 => None,
117 CharsError::Other(ref e: &Error) => e.source(),
118 }
119 }
120}
121
122impl fmt::Display for CharsError {
123 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
124 match *self {
125 CharsError::NotUtf8 => "byte stream did not contain valid utf8".fmt(f),
126 CharsError::Other(ref e: &Error) => e.fmt(f),
127 }
128 }
129}
130