Trait Adapter

Source

pub trait Adapter {
    type Item;

    // Required method
    fn adapt(&mut self, v: Option<Result<Vec<u8>, RcErr>>) -> Option<Self::Item>;
}

Expand description

Trait used to implement a CustomChunker by transforming the output of a ByteChunker.

This is more powerful than simply calling .map(), .map_while(), or .filter_map() on a ByteChunker because the type implementing Adapter can be stateful.

The example below shows a struct implementing Adapter to count the number of chunks returned so far.

use regex_chunker::{Adapter, ByteChunker, RcErr};
use std::io::Cursor;

struct ChunkCounter {
    lines: usize,
}

impl Adapter for ChunkCounter {
    type Item = Result<Vec<u8>, RcErr>;

    fn adapt(&mut self, v: Option<Result<Vec<u8>, RcErr>>) -> Option<Self::Item> {
        match v {
            Some(Ok(v)) => {
                self.lines += 1;
                Some(Ok(v))
            },
            x => x,
        }
    }
}

let text =
br#"What's he that wishes so?
My cousin Westmoreland? No, my fair cousin:
If we are mark'd to die, we are enow
To do our country loss; and if to live,
The fewer men, the greater share of honour."#;

let c = Cursor::new(text);

let mut chunker = ByteChunker::new(c, r#"\r?\n"#)?
    .with_adapter(ChunkCounter { lines: 0 });

let _: Vec<String> = (&mut chunker).map(|res| {
    let v: Vec<u8> = res.unwrap();
    String::from_utf8(v).unwrap()
}).collect();

// Prints "5".
println!("{}", &chunker.get_adapter().lines);