/* relish: versatile lisp shell
 * Copyright (C) 2021 Aidan Hahn
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

use std::boxed::Box;
use std::collections::HashMap;
use crate::cell::{Ctr};

/* Mapping between a string token and a tree of Cells
 * The string token can be found in any Ctr::Symbol value
 *
 * Considerations: should I use a structure of cells for this?
 * Current thoughts: if this was a language without proper data types, yes.
 */
pub type VTable = HashMap<String, Box<Ctr>>;

pub fn define(
    vt: Box<VTable>,
    identifier: String,
    var_tree: Box<Ctr>
) {
    if let Some(boxed_cell) = vt.insert(identifier, var_tree) {
        drop(boxed_cell);
    }
}

pub fn get(
    vt: Box<VTable>,
    identifier: String
) -> Option<Box<Ctr>> {
    if let Some(c) = vt.get(&identifier) {
        Some(*c)
    } else {
        None
    }
}