Trait sise::MaybeMultilineOptions[−][src]

pub trait MaybeMultilineOptions: Default {
    fn break_line() -> Self;
    fn break_line_at(len: usize) -> Self;
    fn no_break_line() -> Self;
}

Expand description

Trait to represent multi-line write options, that may be honored or ignored depending on the writer. Types used for Writer::AtomOptions, Writer::BeginListOptions, Writer::EndListOptions and Writer::FinishOptions shall implement this trait and ignore unsupported options.

Example

use sise::MaybeMultilineOptions as _;

// Function that writes some hardcoded nodes into `writer`.
fn write<W: sise::Writer>(mut writer: W) -> Result<(), W::Error>
where
    W::AtomOptions: sise::MaybeMultilineOptions,
    W::BeginListOptions: sise::MaybeMultilineOptions,
    W::EndListOptions: Default,
    W::FinishOptions: Default,
{
    writer.begin_list(W::BeginListOptions::default())?;
    writer.write_atom("example", W::AtomOptions::no_break_line())?;
    writer.begin_list(W::BeginListOptions::break_line())?;
    // Write the three atoms in a single line.
    writer.write_atom("1", W::AtomOptions::no_break_line())?;
    writer.write_atom("2", W::AtomOptions::no_break_line())?;
    writer.write_atom("3", W::AtomOptions::no_break_line())?;
    writer.end_list(W::EndListOptions::default())?;
    writer.begin_list(W::BeginListOptions::break_line())?;
    // Write the three atoms in a single line.
    writer.write_atom("a", W::AtomOptions::no_break_line())?;
    writer.write_atom("b", W::AtomOptions::no_break_line())?;
    writer.write_atom("c", W::AtomOptions::no_break_line())?;
    writer.end_list(W::EndListOptions::default())?;
    writer.end_list(W::EndListOptions::default())?;
    writer.finish(W::FinishOptions::default())?;
    Ok(())
}

// Write with spaced writer, break line options shall
// be honored.
let style = sise::SpacedStringWriterStyle {
    line_break: "\n",
    indentation: " ",
};

let mut result = String::new();
let mut writer = sise::SpacedStringWriter::new(style, &mut result);
write(writer).unwrap();
let expected_result = "(example\n (1 2 3)\n (a b c)\n)";
assert_eq!(result, expected_result);

// Write with compact writer, options will be ignored.
let mut result = String::new();
let mut writer = sise::CompactStringWriter::new(&mut result);
write(writer).unwrap();
let expected_result = "(example (1 2 3) (a b c))";
assert_eq!(result, expected_result);