diff --git a/src/libstd/fs.rs b/src/libstd/fs.rs index 733ae6d5ccd..ab028802182 100644 --- a/src/libstd/fs.rs +++ b/src/libstd/fs.rs @@ -251,6 +251,47 @@ pub fn read>(path: P) -> io::Result> { Ok(bytes) } +/// Read the entire contents of a file into a string. +/// +/// This is a convenience function for using [`File::open`] and [`read_to_string`] +/// with fewer imports and without an intermediate variable. +/// +/// [`File::open`]: struct.File.html#method.open +/// [`read_to_string`]: ../io/trait.Read.html#method.read_to_string +/// +/// # Errors +/// +/// This function will return an error if `path` does not already exist. +/// Other errors may also be returned according to [`OpenOptions::open`]. +/// +/// [`OpenOptions::open`]: struct.OpenOptions.html#method.open +/// +/// It will also return an error if it encounters while reading an error +/// of a kind other than [`ErrorKind::Interrupted`], +/// or if the contents of the file are not valid UTF-8. +/// +/// [`ErrorKind::Interrupted`]: ../../std/io/enum.ErrorKind.html#variant.Interrupted +/// +/// # Examples +/// +/// ```no_run +/// #![feature(fs_read_write)] +/// +/// use std::fs; +/// use std::net::SocketAddr; +/// +/// # fn foo() -> Result<(), Box> { +/// let foo: SocketAddr = fs::read_utf8("address.txt")?.parse()?; +/// # Ok(()) +/// # } +/// ``` +#[unstable(feature = "fs_read_write", issue = /* FIXME */ "0")] +pub fn read_utf8>(path: P) -> io::Result { + let mut string = String::new(); + File::open(path)?.read_to_string(&mut string)?; + Ok(string) +} + /// Write a slice as the entire contents of a file. /// /// This function will create a file if it does not exist, @@ -1980,7 +2021,9 @@ mod tests { ) } #[cfg(unix)] - macro_rules! error { ($e:expr, $s:expr) => ( + macro_rules! error { ($e:expr, $s:expr) => ( error_contains!($e, $s) ) } + + macro_rules! error_contains { ($e:expr, $s:expr) => ( match $e { Ok(_) => panic!("Unexpected success. Should've been: {:?}", $s), Err(ref err) => assert!(err.to_string().contains($s), @@ -2999,6 +3042,15 @@ mod tests { check!(fs::write(&tmpdir.join("test"), &bytes)); let v = check!(fs::read(&tmpdir.join("test"))); assert!(v == &bytes[..]); + + check!(fs::write(&tmpdir.join("not-utf8"), &[0xFF])); + error_contains!(fs::read_utf8(&tmpdir.join("not-utf8")), + "stream did not contain valid UTF-8"); + + let s = "𐁁𐀓𐀠𐀴𐀍"; + check!(fs::write(&tmpdir.join("utf8"), s.as_bytes())); + let string = check!(fs::read_utf8(&tmpdir.join("utf8"))); + assert_eq!(string, s); } #[test]