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Fix precedence of juxtaposition and fractions

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This commit is contained in:
Tiffany Bennett 2016-08-02 21:08:47 -04:00
parent c8afaaa62a
commit a1d3444a72
1 changed files with 19 additions and 24 deletions
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43
src/unit_defs.rs
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@ -187,30 +187,12 @@ fn parse_pow(mut iter: &mut Iter) -> Expr {
}
}
fn parse_frac(mut iter: &mut Iter) -> Expr {
let left = parse_pow(iter);
match *iter.peek().unwrap() {
Token::Slash => {
iter.next();
let right = parse_frac(iter);
Expr::Frac(Box::new(left), Box::new(right))
},
_ => left
}
}
pub fn parse_expr(mut iter: &mut Iter) -> Expr {
let mut terms = vec![];
loop {
match *iter.peek().unwrap() {
Token::TriplePipe => break,
Token::Newline | Token::Comment | Token::Eof => {
iter.next();
break
},
_ => terms.push(parse_frac(iter))
}
}
fn parse_mul(mut iter: &mut Iter) -> Expr {
let mut terms = vec![parse_pow(iter)];
loop { match *iter.peek().unwrap() {
Token::Slash | Token::TriplePipe | Token::Newline | Token::Comment | Token::Eof => break,
_ => terms.push(parse_pow(iter))
}}
if terms.len() == 1 {
terms.pop().unwrap()
} else {
@ -218,6 +200,19 @@ pub fn parse_expr(mut iter: &mut Iter) -> Expr {
}
}
pub fn parse_expr(mut iter: &mut Iter) -> Expr {
let left = parse_mul(iter);
let mut terms = vec![];
loop { match *iter.peek().unwrap() {
Token::Slash => {
iter.next();
terms.push(parse_mul(iter));
},
Token::TriplePipe | Token::Newline | Token::Comment | Token::Eof | _ => break,
} }
terms.into_iter().fold(left, |a, b| Expr::Frac(Box::new(a), Box::new(b)))
}
fn parse_unknown(mut iter: &mut Iter) {
loop {
match iter.next().unwrap() {