Rust parsing example

rusttest.rs

use std::env;
use std::error::Error;
use std::fs::File;
use std::io::{BufRead, BufReader};
use std::time::Instant;

#[derive(Debug)]
struct Record {
    words: Vec<String>,
}

impl Record {
    fn new() -> Record {
        Record { words: Vec::new() }
    }

    fn parse(s: &str) -> Record {
        // Record::new()
        Record {
            words: s.split_whitespace().map(str::to_owned).collect(),
        }
    }
}

#[derive(Debug)]
struct Table {
    records: Vec<Record>,
}

impl Table {
    fn new() -> Table {
        Table {
            records: Vec::new(),
        }
    }

    fn parse(mut r: impl BufRead) -> Table {
        let mut tbl = Table::new();
        let mut line = String::new();
        while r.read_line(&mut line).unwrap() > 0 {
            let rec = Record::parse(&line);
            tbl.records.push(rec);
            line.clear();
        }
        tbl
    }
}

fn main() -> Result<(), Box<dyn Error>> {
    let args: Vec<_> = env::args().collect();
    if args.len() < 2 {
        panic!("Must specify file argument")
    }

    let file = File::open(&args[1]).unwrap();

    let timer = Instant::now();
    let tbl = Table::parse(BufReader::new(file));
    let duration = timer.elapsed();

    println!("Time elapsed to parse records: {:?}", duration);
    println!("Number of records: {}", tbl.records.len());

    Ok(())
}