flesh/src/vars.rs

/* 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::cell::RefCell;
use std::rc::Rc;
use std::collections::HashMap;
use crate::segment::{Ctr};

/* Mapping between a string token and a tree of Segments
 * The string token can be found in any Ctr::Symbol value
 * it is expected that the trees stored are already evaluated
 */
pub type VTable = HashMap<String, Rc<Ctr>>;

// WARNING: make sure var_tree is properly evaluated before storing
pub fn define(
    vt: Rc<RefCell<VTable>>,
    identifier: String,
    var_tree: Rc<Ctr>
) {
    if let Some(rc_segment) = vt.borrow_mut().insert(identifier, var_tree) {
        drop(rc_segment);
    }
}