mirror of
https://gitee.com/openharmony/third_party_rust_nom
synced 2024-11-27 09:40:54 +00:00
96 lines
2.5 KiB
Rust
96 lines
2.5 KiB
Rust
#[macro_use]
|
|
extern crate nom;
|
|
|
|
use nom::digit;
|
|
use nom::types::CompleteStr;
|
|
|
|
// Parser definition
|
|
|
|
use std::str::FromStr;
|
|
|
|
// We parse any expr surrounded by parens, ignoring all whitespaces around those
|
|
named!(parens<CompleteStr, i64>, ws!(delimited!( tag!("("), expr, tag!(")") )) );
|
|
|
|
// We transform an integer string into a i64, ignoring surrounding whitespaces
|
|
// We look for a digit suite, and try to convert it.
|
|
// If either str::from_utf8 or FromStr::from_str fail,
|
|
// we fallback to the parens parser defined above
|
|
named!(factor<CompleteStr, i64>, alt!(
|
|
map_res!(
|
|
ws!(digit),
|
|
|s:CompleteStr| { FromStr::from_str(s.0) }
|
|
)
|
|
| parens
|
|
)
|
|
);
|
|
|
|
// We read an initial factor and for each time we find
|
|
// a * or / operator followed by another factor, we do
|
|
// the math by folding everything
|
|
named!(term <CompleteStr, i64>, do_parse!(
|
|
init: factor >>
|
|
res: fold_many0!(
|
|
pair!(alt!(char!('*') | char!('/')), factor),
|
|
init,
|
|
|acc, (op, val): (char, i64)| {
|
|
if op == '*' { acc * val } else { acc / val }
|
|
}
|
|
) >>
|
|
(res)
|
|
)
|
|
);
|
|
|
|
named!(expr <CompleteStr, i64>, do_parse!(
|
|
init: term >>
|
|
res: fold_many0!(
|
|
pair!(alt!(char!('+') | char!('-')), term),
|
|
init,
|
|
|acc, (op, val): (char, i64)| {
|
|
if op == '+' { acc + val } else { acc - val }
|
|
}
|
|
) >>
|
|
(res)
|
|
)
|
|
);
|
|
|
|
#[test]
|
|
fn factor_test() {
|
|
assert_eq!(factor(CompleteStr("3")), Ok((CompleteStr(""), 3)));
|
|
assert_eq!(factor(CompleteStr(" 12")), Ok((CompleteStr(""), 12)));
|
|
assert_eq!(factor(CompleteStr("537 ")), Ok((CompleteStr(""), 537)));
|
|
assert_eq!(factor(CompleteStr(" 24 ")), Ok((CompleteStr(""), 24)));
|
|
}
|
|
|
|
#[test]
|
|
fn term_test() {
|
|
assert_eq!(term(CompleteStr(" 12 *2 / 3")), Ok((CompleteStr(""), 8)));
|
|
assert_eq!(
|
|
term(CompleteStr(" 2* 3 *2 *2 / 3")),
|
|
Ok((CompleteStr(""), 8))
|
|
);
|
|
assert_eq!(term(CompleteStr(" 48 / 3/2")), Ok((CompleteStr(""), 8)));
|
|
}
|
|
|
|
#[test]
|
|
fn expr_test() {
|
|
assert_eq!(expr(CompleteStr(" 1 + 2 ")), Ok((CompleteStr(""), 3)));
|
|
assert_eq!(
|
|
expr(CompleteStr(" 12 + 6 - 4+ 3")),
|
|
Ok((CompleteStr(""), 17))
|
|
);
|
|
assert_eq!(expr(CompleteStr(" 1 + 2*3 + 4")), Ok((CompleteStr(""), 11)));
|
|
}
|
|
|
|
#[test]
|
|
fn parens_test() {
|
|
assert_eq!(expr(CompleteStr(" ( 2 )")), Ok((CompleteStr(""), 2)));
|
|
assert_eq!(
|
|
expr(CompleteStr(" 2* ( 3 + 4 ) ")),
|
|
Ok((CompleteStr(""), 14))
|
|
);
|
|
assert_eq!(
|
|
expr(CompleteStr(" 2*2 / ( 5 - 1) + 3")),
|
|
Ok((CompleteStr(""), 4))
|
|
);
|
|
}
|