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use std::fmt;
use crate::lisp::number::LispNumber;
#[derive(Debug, PartialEq, Clone)]
pub enum LispExpr {
Number(LispNumber),
List(Vec<LispExpr>),
StringLit(String),
BoolLit(bool),
Ident(String),
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::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::Function(_) => write!(f, "<#procedure>")?,
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(())
}
}
#[derive(Debug, PartialEq, Clone)]
struct LispFunction {}
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