63 lines
2.3 KiB
Rust
63 lines
2.3 KiB
Rust
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/* relish: versatile lisp shell
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* Copyright (C) 2021 Aidan Hahn
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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use crate::segment::{Ctr, Seg};
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use crate::eval::eval;
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use crate::sym::SymTable;
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pub fn if_callback (ast: &Seg, syms: &mut SymTable) -> Result<Ctr, String> {
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if let Ctr::Seg(ref cond_form) = *ast.car {
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if let Ctr::Bool(cond) = *eval(cond_form, syms)? {
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if let Ctr::Seg(ref first_form) = *ast.cdr {
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if cond {
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match *first_form.car {
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Ctr::Seg(ref first_arg) => Ok(*eval(first_arg, syms)?),
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_ => Ok(*eval(&Seg::from_mono(first_form.car.clone()), syms)?),
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}
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} else {
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if let Ctr::Seg(ref second_form) = *first_form.cdr {
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match *second_form.car {
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Ctr::Seg(ref second_arg) => Ok(*eval(second_arg, syms)?),
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_ => Ok(*eval(&Seg::from_mono(second_form.car.clone()), syms)?),
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}
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} else {
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Err("impossible condition: args not in standard form".to_string())
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}
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}
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} else {
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Err("impossible condition: not 3 args to if".to_string())
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}
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} else {
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Err("first argument to if must evaluate to be a boolean".to_string())
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}
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} else {
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Err("impossible condition: not 3 args to if".to_string())
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}
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}
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fn let_callback (_ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
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todo!()
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}
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fn while_callback (_ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
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todo!()
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}
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fn map_callback (_ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, String> {
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todo!()
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}
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