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Convert to more lispish Cons

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This commit is contained in:
greg 2017-12-04 03:23:55 -08:00
parent 18d8ca7bd5
commit 0e17e45f3e
1 changed files with 15 additions and 22 deletions
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37
src/rukka_lang/mod.rs
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@ -53,13 +53,9 @@ impl EvaluatorState {
SymbolAtom(sym) => unimplemented!(), SymbolAtom(sym) => unimplemented!(),
expr @ StringAtom(_) => expr, expr @ StringAtom(_) => expr,
expr @ NumberAtom(_) => expr, expr @ NumberAtom(_) => expr,
List(items) => { Cons(ref car, ref cdr) => {
if items.len() == 0 { match **car {
return Ok(List(items)) SymbolAtom(ref sym) => match &sym[..] {
}
let ref first = items[0];
match first {
&SymbolAtom(ref sym) => match &sym[..] {
"quote" => unimplemented!(), "quote" => unimplemented!(),
"eq?" => unimplemented!(), "eq?" => unimplemented!(),
"cons" => unimplemented!(), "cons" => unimplemented!(),
@ -73,7 +69,8 @@ impl EvaluatorState {
}, },
_ => unimplemented!() _ => unimplemented!()
} }
} },
Nil => Nil,
}) })
} }
} }
@ -103,7 +100,8 @@ enum Sexp {
SymbolAtom(String), SymbolAtom(String),
StringAtom(String), StringAtom(String),
NumberAtom(u64), NumberAtom(u64),
List(Vec<Sexp>), Cons(Box<Sexp>, Box<Sexp>),
Nil
} }
impl Sexp { impl Sexp {
@ -113,15 +111,8 @@ impl Sexp {
&SymbolAtom(ref sym) => format!("{}", sym), &SymbolAtom(ref sym) => format!("{}", sym),
&StringAtom(ref s) => format!("\"{}\"", s), &StringAtom(ref s) => format!("\"{}\"", s),
&NumberAtom(ref n) => format!("{}", n), &NumberAtom(ref n) => format!("{}", n),
&List(ref sexprs) => { &Cons(ref car, ref cdr) => format!("({} . {}", car.print(), cdr.print()),
let mut output = String::new(); &Nil => format!("()"),
write!(&mut output, "(").unwrap();
for sexpr in sexprs.iter() {
write!(&mut output, "{}", sexpr.print()).unwrap();
}
write!(&mut output, ")").unwrap();
output
}
} }
} }
} }
@ -178,7 +169,7 @@ fn parse(tokens: &mut Peekable<IntoIter<Token>>) -> Result<Sexp, String> {
Some(RParen) => Err(format!("Unexpected ')'")), Some(RParen) => Err(format!("Unexpected ')'")),
Some(Quote) => { Some(Quote) => {
let quoted = parse(tokens)?; let quoted = parse(tokens)?;
Ok(List(vec![SymbolAtom(format!("quote")), quoted])) Ok(Cons(Box::new(SymbolAtom(format!("quote"))), Box::new(quoted)))
}, },
Some(NumLiteral(n)) => Ok(NumberAtom(n)), Some(NumLiteral(n)) => Ok(NumberAtom(n)),
None => Err(format!("Unexpected end of input")), None => Err(format!("Unexpected end of input")),
@ -188,14 +179,16 @@ fn parse(tokens: &mut Peekable<IntoIter<Token>>) -> Result<Sexp, String> {
fn parse_sexp(tokens: &mut Peekable<IntoIter<Token>>) -> Result<Sexp, String> { fn parse_sexp(tokens: &mut Peekable<IntoIter<Token>>) -> Result<Sexp, String> {
use self::Token::*; use self::Token::*;
use self::Sexp::*; use self::Sexp::*;
let mut vec = Vec::new(); let mut cell = Nil;
loop { loop {
match tokens.peek() { match tokens.peek() {
None => return Err(format!("Unexpected end of input")), None => return Err(format!("Unexpected end of input")),
Some(&RParen) => { tokens.next(); break}, Some(&RParen) => { tokens.next(); break},
_ => vec.push(parse(tokens)?), _ => {
cell = Cons(Box::new(parse(tokens)?), Box::new(cell));
} }
} }
Ok(List(vec)) }
Ok(cell)
} }