#![feature(proc_macro_non_items)]

use parsing::{
    grammar,
    Grammar, Rule, Token,
    Generation,
};

fn print_next_sentences (n: usize, grammar: Grammar) {
    let mut generation = Generation::new (grammar, "Start");
    for _ in 0..n {
        let sentence = generation
            .next_sentence ()
            .unwrap ();
        println! ("{}", sentence);
    }
}

#[test]
fn test_next_sentence () {
    print_next_sentences (100, grammar! {
        Start -> Sentence;
        Sentence -> Name | List " and " Name;
        Name -> "tom" | "dick" | "harry";
        List -> Name | Name ", " List;
    });
    print_next_sentences (100, grammar! {
        Start -> S;
        S -> "abc" | "a" S Q;
        "b" Q "c" -> "bbcc";
        "c" Q -> Q "c";
    });
    print_next_sentences (100, grammar! {
        Start -> Moves;
        // circle-movements-for-manhattan-turtle
        Moves -> "north " Moves "south " | "east " Moves "west " | ε;
        ε -> ;
        // the following are just
        //   swapping pathes generated by the above rule
        "north east " -> "east north ";
        "north south " -> "south north ";
        "north west " -> "west north ";
        "east north " -> "north east ";
        "east south " -> "south east ";
        "east west " -> "west east ";
        "south north " -> "north south ";
        "south east " -> "east south ";
        "south west " -> "west south ";
        "west north " -> "north west ";
        "west east " -> "east west ";
        "west south " -> "south west ";
    });
}