reading-liner

Reading and convert offset and line-column location.

A Stream reader which can convert between byte offset and line-column numbers. Support any type which implements io::Read.

The whole design is based on an Index, which is composed of line information to convert between byte offsets and line-column locations. One perticular usage is to use the Stream as a builder of Index or you can also use it when lazily reading and convert locations at the same time.

This lib should be used at low-level abstraction.

Documentation

The API is documented: https://docs.rs/reading-liner

Core methods

Immutable queries (best practice)

• locate line-column location from byte offset:
  • Query::locate(&self, Offset) -> Option<line_column::ZeroBased>
• encode offset from line-column location
  • Query::encode(&self, line_column::ZeroBased) -> Option<Offset>

Mutable queries

The names are the same with immutable ones, but be careful since these mutable queries may read bytes implicitly.

• locate line-column location from byte offset:
  • Stream::locate(&mut self, Offset) -> io::Result<line_column::ZeroBased>
• encode offset from line-column location
  • Stream::encode(&mut self, line_column::ZeroBased) -> io::Result<Offset>

Example

use reading_liner::{Stream, location::Offset, Index};
use std::io::Read;
use std::{fs, io};

fn example() -> io::Result<()> {
    // build stream
    let file = fs::File::open("foo.rs")?;
    let mut index = Index::new();
    let stream = Stream::new(file, &mut index);

    // wrap BufReader
    let mut reader = io::BufReader::new(stream);
    let mut buf = String::new();
    reader.read_to_string(&mut buf)?;

    // use the built index
    let line_index = index.query().locate(Offset(20)).unwrap();
    dbg!(line_index.one_based());
    Ok(())
}