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use std::{convert::TryFrom, fmt};
use crate::app::AppState;
use crate::lisp::{
error::{EvalError, LispError},
eval::lookup_extended,
number::LispNumber,
EnvList,
};
#[derive(Debug, Copy, PartialEq, Clone)]
pub enum Arity {
Exact(usize),
Atleast(usize),
Atmost(usize),
Range(usize, usize),
None,
}
impl Arity {
pub fn is_valid<T>(self, args: &[T]) -> bool {
match self {
Arity::Exact(a) => args.len() == a,
Arity::Atleast(a) => args.len() >= a,
Arity::Atmost(a) => args.len() <= a,
Arity::Range(low, high) => args.len() >= low && args.len() <= high,
Arity::None => true,
}
}
pub fn to_error(self) -> LispError {
LispError::Eval(EvalError::ArgumentCount(self))
}
}
#[derive(Clone)]
pub struct PrimitiveFunc {
pub arity: Arity, // minimim arity
pub closure: fn(&[LispExpr], &mut AppState) -> Result<LispExpr, LispError>,
}
impl PrimitiveFunc {
pub fn call(&self, args: &[LispExpr], app: &mut AppState) -> Result<LispExpr, LispError> {
if !self.arity.is_valid(args) {
return Err(EvalError::ArgumentCount(self.arity).into());
}
(self.closure)(args, app)
}
}
pub type Ident = String;
pub type BoolLit = bool;
#[derive(Clone)]
pub struct LispFunction {
pub params: Vec<String>,
pub body: Vec<LispExpr>,
}
#[derive(Clone)]
pub enum LispExpr {
Unit,
Number(LispNumber),
List(Vec<LispExpr>),
StringLit(String),
BoolLit(bool),
Ident(Ident),
PrimitiveFunc(PrimitiveFunc),
Function(LispFunction),
Char(char),
// none of these depths should be zero
Quasiquote(Box<LispExpr>, u32),
Comma(Box<LispExpr>, u32),
CommaAt(Box<LispExpr>, u32),
Quote(Box<LispExpr>, u32),
}
impl LispExpr {
pub fn comma(self, n: u32) -> LispExpr {
match self {
LispExpr::Comma(v, i) => LispExpr::Comma(v, i.checked_add(n).expect("comma overflow")),
LispExpr::CommaAt(v, i) => LispExpr::CommaAt(v, i + n),
v => LispExpr::Comma(Box::new(v), n),
}
}
pub fn comma_at(self, n: u32) -> LispExpr {
match self {
LispExpr::CommaAt(v, i) => {
LispExpr::CommaAt(v, i.checked_add(n).expect("comma_at overflow"))
}
v => LispExpr::CommaAt(Box::new(v), n),
}
}
pub fn quote(self, n: u32) -> LispExpr {
match self {
LispExpr::Quote(v, i) => LispExpr::Quote(v, i.checked_add(n).expect("quote overflow")),
v => LispExpr::Quote(Box::new(v), n),
}
}
pub fn quasiquote(self, n: u32) -> LispExpr {
match self {
LispExpr::Quasiquote(v, i) => {
LispExpr::Quasiquote(v, i.checked_add(n).expect("quasiquote overflow"))
}
v => LispExpr::Quasiquote(Box::new(v), n),
}
}
pub fn compare(&self, other: &Self, envs: &EnvList) -> Result<BoolLit, LispError> {
match (self, other) {
(LispExpr::Unit, LispExpr::Unit) => Ok(true),
(LispExpr::Number(s), LispExpr::Number(o)) => Ok(s == o),
(LispExpr::List(s), LispExpr::List(o)) => Ok(s
.iter()
.zip(o)
.all(|(a, b)| matches!(a.compare(b, envs), Ok(true)))),
(LispExpr::StringLit(s), LispExpr::StringLit(o)) => Ok(s == o),
(LispExpr::Char(s), LispExpr::Char(o)) => Ok(s == o),
(LispExpr::BoolLit(s), LispExpr::BoolLit(o)) => Ok(s == o),
(LispExpr::Ident(s), LispExpr::Ident(o)) => {
let s = lookup_extended(envs, s)?;
let o = lookup_extended(envs, o)?;
s.compare(&o, envs)
}
(LispExpr::PrimitiveFunc(s), LispExpr::PrimitiveFunc(o)) => {
let PrimitiveFunc { closure: s, .. } = s;
let PrimitiveFunc { closure: o, .. } = o;
Ok(*s as usize == *o as usize)
}
(LispExpr::Function(_), LispExpr::Function(_)) => Err(EvalError::BadForm.into()),
(LispExpr::Quasiquote(s, sd), LispExpr::Quasiquote(o, od)) => {
Ok(s.compare(o, envs)? && sd == od)
}
(LispExpr::Comma(s, sd), LispExpr::Comma(o, od)) => Ok(s.compare(o, envs)? && sd == od),
(LispExpr::CommaAt(s, sd), LispExpr::CommaAt(o, od)) => {
Ok(s.compare(o, envs)? && sd == od)
}
(LispExpr::Quote(s, sd), LispExpr::Quote(o, od)) => Ok(s.compare(o, envs)? && sd == od),
_ => Err(EvalError::TypeMismatch.into()),
}
}
}
impl fmt::Display for LispExpr {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
LispExpr::Unit => write!(f, "()")?,
LispExpr::Number(n) => write!(f, "{}", n)?,
LispExpr::List(l) => {
for expr in l.iter() {
write!(f, " {} ", expr)?
}
}
LispExpr::StringLit(s) => write!(f, "{}", s)?,
LispExpr::Char(c) => write!(f, "{}", c)?,
LispExpr::BoolLit(b) => {
if *b {
write!(f, "#t")?
} else {
write!(f, "#f")?
}
}
LispExpr::Ident(s) => write!(f, "{}", s)?,
LispExpr::PrimitiveFunc(_) => write!(f, "<#primitive>")?,
LispExpr::Function(func) => write!(f, "<#lambda {}>", func.params.join(" "))?,
LispExpr::Quasiquote(val, depth) => {
write!(f, "{}{}", "`".repeat(*depth as usize), val)?
}
LispExpr::Comma(val, depth) => write!(f, "{}{}", ",".repeat(*depth as usize), val)?,
LispExpr::CommaAt(val, depth) => write!(f, "{}@{}", ",".repeat(*depth as usize), val)?,
LispExpr::Quote(val, depth) => write!(f, "{}{}", "'".repeat(*depth as usize), val)?,
};
Ok(())
}
}
impl TryFrom<LispExpr> for LispNumber {
type Error = LispError;
fn try_from(value: LispExpr) -> Result<Self, Self::Error> {
match value {
LispExpr::Number(i) => Ok(i),
_ => Err(LispError::Eval(EvalError::TypeMismatch)),
}
}
}
impl<'a> TryFrom<&'a LispExpr> for &'a LispNumber {
type Error = LispError;
fn try_from(value: &'a LispExpr) -> Result<Self, Self::Error> {
match value {
LispExpr::Number(i) => Ok(i),
_ => Err(LispError::Eval(EvalError::TypeMismatch)),
}
}
}
//impl TryFrom<LispExpr> for Ident {
// type Error = LispError;
// fn try_from(value: LispExpr) -> Result<Self, Self::Error> {
// match value {
// LispExpr::Ident(i) => Ok(i),
// _ => Err(LispError::Eval(EvalError::TypeMismatch)),
// }
// }
//}
//
//
impl TryFrom<LispExpr> for String {
type Error = LispError;
fn try_from(value: LispExpr) -> Result<Self, Self::Error> {
match value {
LispExpr::StringLit(i) => Ok(i),
_ => Err(LispError::Eval(EvalError::TypeMismatch)),
}
}
}
impl AsRef<str> for LispExpr {
fn as_ref(&self) -> &str {
match self {
LispExpr::StringLit(i) => &i,
LispExpr::Ident(i) => &i,
_ => panic!("invalid downcast!"),
}
}
}
impl TryFrom<LispExpr> for BoolLit {
type Error = LispError;
fn try_from(value: LispExpr) -> Result<Self, Self::Error> {
match value {
LispExpr::BoolLit(i) => Ok(i),
_ => Err(LispError::Eval(EvalError::TypeMismatch)),
}
}
}
pub fn is_ident<E: AsRef<LispExpr>>(expr: E) -> bool {
matches!(expr.as_ref(), LispExpr::Ident(_))
}
pub fn is_number<E: AsRef<LispExpr>>(expr: E) -> bool {
matches!(expr.as_ref(), LispExpr::Number(_))
}
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