I can has RTFM!

[HologramOfMe]

I know it must have happened before. Surely it's happened before. BUT maybe for the first time while playing with Rust, I solved a challenge by RTFM. This is a step in the right direction.

It was on "11_hashmaps". I got successfully through the second but after comparing what I'd done with the given solution, I saw that I had really taken the long route due to my lack of awareness of available methods. As a result of that, on the third exercise, I found myself flicking through HashMap methods a bit more to see what was there when I happened upon .and_modify().

This is what I came up with.

fn build_scores_table(results: &str) -> HashMap<&str, TeamScores> {
    // The name of the team is the key and its associated struct is the value.
    let mut scores = HashMap::<&str, TeamScores>::new();

    for line in results.lines() {
        let mut split_iterator = line.split(',');
        // NOTE: We use `unwrap` because we didn't deal with error handling yet.
        let team_1_name = split_iterator.next().unwrap();
        let team_2_name = split_iterator.next().unwrap();
        let team_1_score: u8 = split_iterator.next().unwrap().parse().unwrap();
        let team_2_score: u8 = split_iterator.next().unwrap().parse().unwrap();

        // TODO: Populate the scores table with the extracted details.
        // Keep in mind that goals scored by team 1 will be the number of goals
        // conceded by team 2. Similarly, goals scored by team 2 will be the
        // number of goals conceded by team 1.
        scores
            .entry(team_1_name)
            .and_modify(|teamscores| {
                teamscores.goals_scored += team_1_score;
                teamscores.goals_conceded += team_2_score;
            })
            .or_insert(TeamScores {
                goals_scored: team_1_score,
                goals_conceded: team_2_score,
            });

        scores
            .entry(team_2_name)
            .and_modify(|teamscores| {
                teamscores.goals_scored += team_2_score;
                teamscores.goals_conceded += team_1_score;
            })
            .or_insert(TeamScores {
                goals_scored: team_2_score,
                goals_conceded: team_1_score,
            });
    }

    scores
}

It's not quite as slick as the given solution to that challenge. But the point here is, I Read The F'n Manual. And it paid off.