utf8_io/
copy.rs

1use crate::{ReadStr, WriteStr};
2use std::io;
3#[cfg(feature = "layered-io")]
4use {crate::ReadStrLayered, layered_io::Bufferable, std::cmp::max};
5
6const DEFAULT_BUF_SIZE: usize = 8 * 1024;
7
8/// Like `std::io::copy`, but for streams that can operate directly on strings,
9/// so we can avoid re-validating them as UTF-8.
10pub fn copy_str<R: ReadStr + ?Sized, W: WriteStr + ?Sized>(
11    reader: &mut R,
12    writer: &mut W,
13) -> io::Result<u64> {
14    // TODO: Avoid unnecessary zero-initialization.
15    let mut buf = "\0".repeat(DEFAULT_BUF_SIZE);
16
17    let mut written = 0;
18    loop {
19        let len = match reader.read_str(&mut buf) {
20            Ok(0) => break,
21            Ok(nread) => nread,
22            Err(err) if err.kind() == io::ErrorKind::Interrupted => continue,
23            Err(err) => return Err(err),
24        };
25        writer.write_str(&buf[..len])?;
26        written += len as u64;
27    }
28    Ok(written)
29}
30
31/// Like `std::io::copy`, but for streams that can operate directly on strings,
32/// so we can avoid re-validating them as UTF-8.
33///
34/// Also, like `copy_str`, but uses `read_str_with_status` to avoid performing
35/// an extra `read` at the end.
36#[cfg(feature = "layered-io")]
37pub fn copy_str_using_status<R: ReadStrLayered + ?Sized, W: WriteStr + Bufferable + ?Sized>(
38    reader: &mut R,
39    writer: &mut W,
40) -> io::Result<u64> {
41    // TODO: Avoid unnecessary zero-initialization.
42    let mut buf = "\0".repeat(max(
43        reader.suggested_buffer_size(),
44        writer.suggested_buffer_size(),
45    ));
46
47    let mut written = 0;
48    loop {
49        let (len, status) = reader.read_str_with_status(&mut buf)?;
50        writer.write_str(&buf[..len])?;
51        written += len as u64;
52        if status.is_end() {
53            return Ok(written);
54        }
55        if status.is_push() {
56            writer.flush()?;
57        }
58    }
59}
60
61#[test]
62fn test_copy_str() {
63    use crate::{Utf8Reader, Utf8Writer};
64    use std::io::Cursor;
65    use std::str;
66
67    let text = "hello world ☃";
68    let mut input = Utf8Reader::new(Cursor::new(text.to_string()));
69    let mut output = Utf8Writer::new(Vec::new());
70
71    copy_str(&mut input, &mut output).unwrap();
72
73    let vec = output.into_inner().unwrap();
74    assert_eq!(str::from_utf8(&vec).unwrap(), text);
75}
76
77#[cfg(feature = "layered-io")]
78#[test]
79fn test_copy_str_using_status() {
80    use crate::{Utf8Reader, Utf8Writer};
81    use layered_io::{LayeredReader, LayeredWriter};
82    use std::io::Cursor;
83    use std::str;
84
85    let text = "hello world ☃";
86    let mut input = Utf8Reader::new(LayeredReader::new(Cursor::new(text.to_string())));
87    let mut output = Utf8Writer::new(LayeredWriter::new(Vec::new()));
88
89    copy_str_using_status(&mut input, &mut output).unwrap();
90
91    let ext = output.close_into_inner().unwrap();
92    let vec = ext.abandon_into_inner().unwrap();
93    assert_eq!(str::from_utf8(&vec).unwrap(), text);
94}
utf8_io/copy.rs

utf8_io/
copy.rs
