anstream/
fmt.rs

1/// A shim which allows a [`std::io::Write`] to be implemented in terms of a [`std::fmt::Write`]
2///
3/// This saves off I/O errors. instead of discarding them
4pub(crate) struct Adapter<W>
5where
6    W: FnMut(&[u8]) -> std::io::Result<()>,
7{
8    writer: W,
9    error: std::io::Result<()>,
10}
11
12impl<W> Adapter<W>
13where
14    W: FnMut(&[u8]) -> std::io::Result<()>,
15{
16    pub(crate) fn new(writer: W) -> Self {
17        Adapter {
18            writer,
19            error: Ok(()),
20        }
21    }
22
23    pub(crate) fn write_fmt(mut self, fmt: std::fmt::Arguments<'_>) -> std::io::Result<()> {
24        match std::fmt::write(&mut self, fmt) {
25            Ok(()) => Ok(()),
26            Err(..) => {
27                // check if the error came from the underlying `Write` or not
28                if self.error.is_err() {
29                    self.error
30                } else {
31                    Err(std::io::Error::new(
32                        std::io::ErrorKind::Other,
33                        "formatter error",
34                    ))
35                }
36            }
37        }
38    }
39}
40
41impl<W> std::fmt::Write for Adapter<W>
42where
43    W: FnMut(&[u8]) -> std::io::Result<()>,
44{
45    fn write_str(&mut self, s: &str) -> std::fmt::Result {
46        match (self.writer)(s.as_bytes()) {
47            Ok(()) => Ok(()),
48            Err(e) => {
49                self.error = Err(e);
50                Err(std::fmt::Error)
51            }
52        }
53    }
54}
anstream/fmt.rs

anstream/
fmt.rs
