use super::ast::{Expression, Program, TopLevel};
use internment::ArcIntern;
use std::collections::HashSet;

impl<T> Program<T> {
    /// Get the complete list of strings used within the program.
    ///
    /// For the purposes of this function, strings are the variables used in
    /// `print` statements.
    pub fn strings(&self) -> HashSet<ArcIntern<String>> {
        let mut result = HashSet::new();

        for stmt in self.items.iter() {
            stmt.register_strings(&mut result);
        }

        result
    }
}

impl<T> TopLevel<T> {
    fn register_strings(&self, string_set: &mut HashSet<ArcIntern<String>>) {
        match self {
            TopLevel::Function(_, _, _, body) => body.register_strings(string_set),
            TopLevel::Statement(stmt) => stmt.register_strings(string_set),
        }
    }
}

impl<T> Expression<T> {
    fn register_strings(&self, _string_set: &mut HashSet<ArcIntern<String>>) {
        // nothing has a string in here, at the moment
        unimplemented!()
    }
}