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use std::{convert::TryFrom, fmt};
use crate::app::AppState;
use crate::lisp::{
error::{EvalError, LispError},
number::LispNumber,
};
#[derive(Clone)]
pub struct PrimitiveFunc {
pub arity: Option<usize>, // 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 let Some(arity) = self.arity {
if args.len() < arity {
return Err(EvalError::ArgumentCount(self.arity.map(|u| u as u32)).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),
// 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),
}
}
}
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::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 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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