Counting words, inspired by http://jmoiron.net/blog/cpp-deserves-its-bad-reputation/

words.rs

use anyhow::Result;
use std::fs::File;
use std::io::{BufRead, BufReader};
use walkdir::WalkDir;

/// Inspired by http://jmoiron.net/blog/cpp-deserves-its-bad-reputation/

fn main() -> Result<()> {
    let mut counter = std::collections::BTreeMap::new();

    for entry in WalkDir::new(".")
        .follow_links(true)
        .into_iter()
        .filter_map(|e| e.ok())
        .filter(|e| e.file_name().to_string_lossy().ends_with(".txt"))
    {
        let reader = BufReader::new(File::open(entry.into_path())?);

        for line in reader.lines() {
            for word in line?.split_whitespace() {
                let w = word.to_lowercase().to_string();
                *counter.entry(w).or_insert(0) += 1;
            }
        }
    }

    let mut tops: Vec<_> = counter.iter().map(|(w, c)| (c, w)).collect();
    tops.sort_by_key(|(&c, w)| (std::cmp::Reverse(c), *w));

    for (c, w) in tops.iter().take(10) {
        println!("{} - {}", w, c);
    }

    Ok(())
}