use super::EnvironmentTrait;
use super::ExpressionTrait as Expression;
use std::collections::HashMap;

pub struct Environment<X: Expression> {
    map: HashMap<String, X>,
}

impl<X: Expression> Environment<X> {
    pub fn new() -> Environment<X> {
        Environment {
            map: HashMap::new(),
        }
    }
}

impl<X: Expression> EnvironmentTrait<X> for Environment<X> {
    fn get_expression(&self, identifier: &str) -> Option<&X> {
        return self.map.get(identifier);
    }
}