bytestring.rs.html -- source
Description: Source to the Rust file `libstd/sys_common/bytestring.rs`.
Keywords: rust, rustlang, rust-lang

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    // Copyright 2014 The Rust Project Developers. See the COPYRIGHT
    // file at the top-level directory of this distribution and at
    // http://rust-lang.org/COPYRIGHT.
    //
    // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
    // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
    // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
    // option. This file may not be copied, modified, or distributed
    // except according to those terms.

    #![allow(dead_code)]

    use fmt::{Formatter, Result, Write};
    use std_unicode::lossy::{Utf8Lossy, Utf8LossyChunk};

    pub fn debug_fmt_bytestring(slice: &[u8], f: &mut Formatter) -> Result {
        // Writes out a valid unicode string with the correct escape sequences
        fn write_str_escaped(f: &mut Formatter, s: &str) -> Result {
            for c in s.chars().flat_map(|c| c.escape_debug()) {
                f.write_char(c)?
            }
            Ok(())
        }

        f.write_str("\"")?;
        for Utf8LossyChunk { valid, broken } in Utf8Lossy::from_bytes(slice).chunks() {
            write_str_escaped(f, valid)?;
            for b in broken {
                write!(f, "\\x{:02X}", b)?;
            }
        }
        f.write_str("\"")
    }

    #[cfg(test)]
    mod tests {
        use super::*;
        use fmt::{Formatter, Result, Debug};

        #[test]
        fn smoke() {
            struct Helper<'a>(&'a [u8]);

            impl<'a> Debug for Helper<'a> {
                fn fmt(&self, f: &mut Formatter) -> Result {
                    debug_fmt_bytestring(self.0, f)
                }
            }

            let input =      b"\xF0hello,\tworld";
            let expected = r#""\xF0hello,\tworld""#;
            let output = format!("{:?}", Helper(input));

            assert!(output == expected);
        }
    }

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