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

impl Program {
    /// 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.statements.iter() {
            stmt.register_strings(&mut result);
        }

        result
    }
}

impl Statement {
    fn register_strings(&self, string_set: &mut HashSet<ArcIntern<String>>) {
        match self {
            Statement::Binding(_, name, expr) => {
                string_set.insert(name.clone());
                expr.register_strings(string_set);
            }

            Statement::Print(_, name) => {
                string_set.insert(name.clone());
            }
        }
    }
}

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