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) => match item {
46 Some(item) => item,
47 None => return None,
48 },
49 };
50
51 let width = utf8_char_width(first_byte);
52 if width == 1 {
53 return Some(Ok(first_byte as char));
54 }
55 if width == 0 {
56 return Some(Err(CharsError::NotUtf8));
57 }
58 let mut buf = [first_byte, 0, 0, 0];
59 {
60 let mut start = 1;
61 while start < width {
62 let byte = match self.get_next() {
63 Err(err) => return Some(Err(err)),
64 Ok(item) => match item {
65 Some(item) => item,
66 None => return Some(Err(CharsError::NotUtf8)),
67 },
68 };
69 buf[start] = byte;
70 start += 1;
71 }
72 }
73 Some(match from_utf8(&buf[..width]).ok() {
74 Some(s) => Ok(s.chars().next().unwrap()),
75 None => Err(CharsError::NotUtf8),
76 })
77 }
78}
79
80fn utf8_char_width(b: u8) -> usize {
81 UTF8_CHAR_WIDTH[b as usize] as usize
82}
83
84// https://tools.ietf.org/html/rfc3629
85static UTF8_CHAR_WIDTH: [u8; 256] = [
86 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,
87 1, // 0x1F
88 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,
89 1, // 0x3F
90 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,
91 1, // 0x5F
92 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,
93 1, // 0x7F
94 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,
95 0, // 0x9F
96 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,
97 0, // 0xBF
98 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,
99 2, // 0xDF
100 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, // 0xEF
101 4, 4, 4, 4, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0xFF
102];
103
104/// An enumeration of possible errors that can be generated from the `Chars`
105/// adapter.
106#[derive(Debug)]
107pub enum CharsError {
108 /// Variant representing that the underlying stream was read successfully
109 /// but it did not contain valid utf8 data.
110 NotUtf8,
111
112 /// Variant representing that an I/O error occurred.
113 Other(Error),
114}
115
116impl error::Error for CharsError {
117 fn cause(&self) -> Option<&dyn error::Error> {
118 match *self {
119 CharsError::NotUtf8 => None,
120 CharsError::Other(ref e: &Error) => e.source(),
121 }
122 }
123}
124
125impl fmt::Display for CharsError {
126 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
127 match *self {
128 CharsError::NotUtf8 => "byte stream did not contain valid utf8".fmt(f),
129 CharsError::Other(ref e: &Error) => e.fmt(f),
130 }
131 }
132}
133