116 lines
3.0 KiB
Rust
116 lines
3.0 KiB
Rust
/* Serene --- Yet an other Lisp
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*
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* Copyright (c) 2020 Sameer Rahmani <lxsameer@gnu.org>
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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 2 of the License.
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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::errors::Error;
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use crate::runtime::RT;
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use crate::scope::Scope;
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use crate::types::collections;
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use crate::types::{Number, Symbol};
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use std::fmt;
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pub type PossibleExpr = Result<Expr, Error>;
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#[derive(Debug, Eq, PartialEq, Clone)]
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pub struct Location {
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position: i64,
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file_path: String,
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}
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impl fmt::Display for Location {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "'{}:{}'", &self.file_path, &self.position)
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}
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}
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pub trait Expression {
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fn location(&self) -> Location {
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Location {
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position: 0,
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file_path: "NotImplemented".to_string(),
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}
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}
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fn eval(&self, rt: &RT, scope: &Scope) -> PossibleExpr;
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}
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/// It differs from the `fmt::Display` in the way that anything that
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/// we want to show in a repl as the result of an evaluation and needs
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/// the runtime details has to implement this trait. But we use the
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/// `fmt::Display` as a formatter and in a way that it doesn't need the
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/// runtime.
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pub trait StringRepr {
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fn string_repr(&self, rt: &RT) -> String;
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}
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#[derive(Debug, Eq, PartialEq, Clone)]
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pub enum Expr {
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Sym(Symbol),
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Str(String),
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Num(Number),
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Comment,
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Error(String),
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Cons(collections::List),
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Nil,
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NoMatch,
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}
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impl Expr {
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pub fn make_list(elements: &[Expr]) -> Expr {
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Expr::Cons(collections::List::new(elements))
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}
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pub fn list_to_cons(l: collections::List) -> Expr {
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Expr::Cons(l)
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}
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pub fn make_empty_list() -> collections::List {
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collections::List::new_empty()
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}
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pub fn make_symbol(v: String, target_ns: Option<String>) -> Expr {
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Expr::Sym(Symbol::new(v, target_ns))
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}
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pub fn make_string(v: String) -> Expr {
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Expr::Str(v)
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}
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pub fn make_number(n: Number) -> Expr {
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Expr::Num(n)
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}
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}
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impl fmt::Display for Expr {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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match self {
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Expr::Num(n) => n.fmt(f),
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Expr::Sym(s) => s.fmt(f),
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_ => write!(f, "NA"),
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}
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}
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}
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impl StringRepr for Expr {
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fn string_repr(&self, rt: &RT) -> String {
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match self {
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Expr::Num(n) => n.string_repr(rt),
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Expr::Sym(s) => s.string_repr(rt),
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Expr::Cons(c) => c.string_repr(rt),
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_ => "NA".to_string(),
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}
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}
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}
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