canic-utils 0.19.0

// to_title_case
pub fn to_title_case(input: &str) -> String {
    // Common small words that are not usually capitalized in titles
    const SMALL_WORDS: [&str; 14] = [
        "a", "and", "as", "at", "by", "for", "in", "nor", "of", "on", "or", "the", "to", "with",
    ];

    // Split the input into words once and store it in a vector
    let words: Vec<&str> = input.split_whitespace().collect();
    let len = words.len();

    // Map the words to a new vector with proper capitalization
    let capitalized_words: Vec<String> = words
        .iter()
        .enumerate()
        .map(|(i, &word)| {
            // Always capitalize the first and last word or words not in SMALL_WORDS
            if i == 0 || i == len - 1 || !SMALL_WORDS.contains(&word.to_lowercase().as_str()) {
                capitalize_first(word)
            } else {
                word.to_lowercase()
            }
        })
        .collect();

    capitalized_words.join(" ")
}

// Helper function to capitalize the first letter of a word
fn capitalize_first(word: &str) -> String {
    let mut chars = word.chars();
    if let Some(first) = chars.next() {
        first.to_uppercase().collect::<String>() + chars.as_str()
    } else {
        String::new()
    }
}

///
/// TESTS
///

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_to_title() {
        let test_cases = vec![
            ("Come by", "Come By"),
            ("test me", "Test Me"),
            ("Test Me", "Test Me"),
            ("Group Of Green Sacks", "Group of Green Sacks"),
            ("Spaces ", "Spaces"),
            ("Spaces   ", "Spaces"),
            ("   Spaces", "Spaces"),
            ("   Spaces   ", "Spaces"),
            ("    non title text ", "Non Title Text"),
            (" the   book    of peas ", "The Book of Peas"),
            ("I'm loving it", "I'm Loving It"), // Short forms
            ("war and peace", "War and Peace"), // Short words
        ];

        for (input, expected) in test_cases {
            assert_eq!(to_title_case(input), expected);
        }
    }
}