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Impl fmt::Write for AsciiString, and add tests #33

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Merged
merged 3 commits into from
Feb 9, 2017
Merged

Impl fmt::Write for AsciiString, and add tests #33

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e2094fc
Impl fmt::Write for AsciiString, and add tests
burtonageo Feb 8, 2017
acfb90b
Small simplifying refactor
burtonageo Feb 8, 2017
f7220f4
Simplify use statements in write_fmt test
burtonageo Feb 9, 2017
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33 changes: 32 additions & 1 deletion src/ascii_string.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -466,6 +466,20 @@ impl fmt::Debug for AsciiString {
}
}

impl fmt::Write for AsciiString {
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I'll add some documentation that fmt::Write methods "[do] not support transmission of an error other than that an error occurred." (from std::fmt::Error). This is just to remind users of this API how to handle errors correctly.

fn write_str(&mut self, s: &str) -> fmt::Result {
let astr = try!(AsciiStr::from_ascii(s).map_err(|_| fmt::Error));
self.push_str(astr);
Ok(())
}

fn write_char(&mut self, c: char) -> fmt::Result {
let achar = try!(AsciiChar::from(c).map_err(|_| fmt::Error));
self.push(achar);
Ok(())
}
}

impl FromIterator<AsciiChar> for AsciiString {
fn from_iter<I: IntoIterator<Item=AsciiChar>>(iter: I) -> AsciiString {
let mut buf = AsciiString::new();
Expand Down Expand Up @@ -644,7 +658,6 @@ impl IntoAsciiString for String {
}
}


#[cfg(test)]
mod tests {
use std::str::FromStr;
Expand Down Expand Up @@ -675,4 +688,22 @@ mod tests {
assert_eq!(format!("{}", s), "abc".to_string());
assert_eq!(format!("{:?}", s), "\"abc\"".to_string());
}

#[test]
fn write_fmt() {
use std::{fmt, str};

let mut s0 = AsciiString::new();
fmt::write(&mut s0, format_args!("Hello World")).unwrap();
assert_eq!(s0, "Hello World");

let mut s1 = AsciiString::new();
fmt::write(&mut s1, format_args!("{}", 9)).unwrap();
assert_eq!(s1, "9");

let mut s2 = AsciiString::new();
let sparkle_heart_bytes = [240, 159, 146, 150];
let sparkle_heart = str::from_utf8(&sparkle_heart_bytes).unwrap();
assert!(fmt::write(&mut s2, format_args!("{}", sparkle_heart)).is_err());
}
}