flesh/src/stl/boolean.rs

/* 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 crate::segment::{Ctr, Seg};
use crate::sym::{SymTable, ValueType};

pub fn bool_and_callback(ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
    let mut type_error = false;
    let result = ast.circuit(&mut |arg: &Ctr| -> bool {
        if let Ctr::Bool(b) = *arg {
            b
        } else {
            eprintln!("{} is not a boolean", arg);
            type_error = true;
            false
        }
    });

    if type_error {
        Err("all arguments to and must evaluate to boolean".to_string())
    } else {
        Ok(Ctr::Bool(result))
    }
}

pub fn bool_or_callback(ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
    let mut result = false;
    let correct_types = ast.circuit(&mut |arg: &Ctr| -> bool {
        if let Ctr::Bool(b) = *arg {
            result = result || b;
            true
        } else {
            eprintln!("{} is not a boolean", arg);
            false
        }
    });

    if !correct_types {
        Err("all arguments to 'or' must evaluate to boolean".to_string())
    } else {
        Ok(Ctr::Bool(result))
    }
}

pub fn bool_not_callback(ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
    if let Ctr::Bool(b) = *ast.car {
        Ok(Ctr::Bool(!b))
    } else {
        Err("impossible state: non bool given to not".to_string())
    }
}

pub fn bool_iseq_callback(ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
    let head_ctr_ref = &*ast.car;
    Ok(Ctr::Bool(ast.circuit(&mut |arg: &Ctr| -> bool {arg == head_ctr_ref})))
}

pub fn bool_toggle_callback(ast: &Seg, syms: &mut SymTable) -> Result<Ctr, String> {
    let var_name: String;
    if let Ctr::Symbol(ref s) = *ast.car  {
         var_name = s.clone();
    } else {
        return Err("argument to toggle should be a symbol".to_string())
    }

    let mut sym = syms.remove(&var_name).expect(&format!("symbol {var_name} is not defined"));
    if let ValueType::VarForm(ref var) = sym.value {
        if let Ctr::Bool(ref b) = **var {
            sym.value = ValueType::VarForm(Box::new(Ctr::Bool(!b)));
        } else {
            syms.insert(var_name, sym);
            return Err("can only toggle a boolean".to_string())
        }
    } else {
        syms.insert(var_name, sym);
        return Err("cannot toggle a function".to_string())
    }

    syms.insert(var_name, sym);
    Ok(Ctr::None)
}