schala/schala-lang/src/parsing/combinator.rs

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2021-11-16 20:23:27 -08:00
use nom::{
Err,
branch::alt,
bytes::complete::tag,
character::complete::{char, one_of, space0, space1, multispace0, line_ending},
combinator::{peek, not, value, map},
error::{context, VerboseError, ParseError},
multi::{fold_many1, many1, many0, separated_list1},
sequence::{tuple, preceded},
IResult, Parser,
};
type ParseResult<'a, O> = IResult<&'a str, O, VerboseError<&'a str>>;
use crate::ast::*;
/*
fn block(input: &str) -> ParseResult<Block> {
context("block",
map(
tuple((
char('{'),
value((), context("TOP", many0(alt((line_separator, ws))))),
block_items,
value((), many0(alt((line_separator, ws)))),
char('}'),
)), |(_, _, items, _, _)| items.into()))(input)
}
*/
fn tok<'a, O>(input_parser: impl Parser<&'a str, O, VerboseError<&'a str>>) -> impl FnMut(&'a str) -> IResult<&'a str, O, VerboseError<&'a str>> {
map(tuple((ws0, input_parser)), |(_, output)| output)
}
// whitespace does consume at least one piece of whitespace - use ws0 for maybe none
fn whitespace(input: &str) -> ParseResult<()> {
context("whitespace",
alt((
value((), space1),
line_comment,
block_comment,
)))(input)
}
fn ws0(input: &str) -> ParseResult<()> {
context("WS0",
value((), many0(whitespace)))(input)
}
fn line_comment(input: &str) -> ParseResult<()> {
value((),
tuple((tag("//"), many0(not(line_ending)), peek(line_ending)))
)(input)
}
fn block_comment(input: &str) -> ParseResult<()> {
value((),
tuple((
tag("/*"),
many0(alt((
block_comment,
not(tag("*/"))
))),
tag("*/")
)))(input)
}
fn line_separator(input: &str) -> ParseResult<()> {
alt((value((), line_ending), value((), char(';'))))(input)
}
fn block_items(input: &str) -> ParseResult<Vec<Statement>> {
context("Block-item",
separated_list1(
preceded(context("LLLL", ws0), many1(line_separator)),
statement,
))(input)
}
fn statement(input: &str) -> ParseResult<Statement> {
context("Parsing-statement",
map(
tuple((
ws0,
expression_kind,
ws0
)),|(_, kind, _)| Statement {
id: Default::default(),
location: Default::default(),
kind: StatementKind::Expression(Expression::new(Default::default(), kind)),
}))(input)
}
pub fn expression_kind(input: &str) -> ParseResult<ExpressionKind> {
context("expression-kind",
alt((
number_literal,
bool_literal,
)))(input)
}
fn bool_literal(input: &str) -> ParseResult<ExpressionKind> {
alt((
map(tok(tag("true")), |_| ExpressionKind::BoolLiteral(true)),
map(tok(tag("false")), |_| ExpressionKind::BoolLiteral(false)),
))(input)
}
fn number_literal(input: &str) -> ParseResult<ExpressionKind> {
map(alt((tok(hex_literal), tok(bin_literal), tok(dec_literal))), ExpressionKind::NatLiteral)(input)
}
fn dec_literal(input: &str) -> ParseResult<u64> {
map(digits(digit_group_dec), |chars: Vec<char>| {
let s: String = chars.into_iter().collect();
s.parse().unwrap()
})(input)
}
fn hex_literal(input: &str) -> ParseResult<u64> {
map(preceded(alt((tag("0x"), tag("0X"))), digits(digit_group_hex)), |chars: Vec<char>| {
let s: String = chars.into_iter().collect();
parse_hex(&s).unwrap()
})(input)
}
fn bin_literal(input: &str) -> ParseResult<u64> {
map(preceded(alt((tag("0b"), tag("0B"))), digits(digit_group_bin)), |chars: Vec<char>| {
let s: String = chars.into_iter().collect();
parse_binary(&s).unwrap()
})(input)
}
fn digits<'a, E: ParseError<&'a str>>(
digit_type: impl Parser<&'a str, Vec<char>, E>,
) -> impl FnMut(&'a str) -> IResult<&'a str, Vec<char>, E> {
map(separated_list1(many1(char('_')), digit_type), |items: Vec<Vec<char>>| {
items.into_iter().flatten().collect()
})
}
fn digit_group_dec(input: &str) -> ParseResult<Vec<char>> {
many1(one_of("0123456789"))(input)
}
fn digit_group_hex(input: &str) -> ParseResult<Vec<char>> {
many1(one_of("0123456789abcdefABCDEF"))(input)
}
fn digit_group_bin(input: &str) -> ParseResult<Vec<char>> {
many1(one_of("01"))(input)
}
fn parse_binary(digits: &str) -> Result<u64, &'static str> {
let mut result: u64 = 0;
let mut multiplier = 1;
for d in digits.chars().rev() {
match d {
'1' => result += multiplier,
'0' => (),
'_' => continue,
_ => unreachable!(),
}
multiplier = match multiplier.checked_mul(2) {
Some(m) => m,
None => return Err("Binary expression will overflow"),
}
}
Ok(result)
}
fn parse_hex(digits: &str) -> Result<u64, &'static str> {
let mut result: u64 = 0;
let mut multiplier: u64 = 1;
for d in digits.chars().rev() {
if d == '_' {
continue;
}
match d.to_digit(16) {
Some(n) => result += n as u64 * multiplier,
None => return Err("Internal parser error: invalid hex digit"),
}
multiplier = match multiplier.checked_mul(16) {
Some(m) => m,
None => return Err("Hexadecimal expression will overflow"),
}
}
Ok(result)
}
#[cfg(test)]
mod test {
use pretty_assertions::assert_eq;
use super::*;
#[test]
fn combinator_test1() {
assert_eq!(digits(digit_group_dec)("342").unwrap().1, vec!['3', '4', '2']);
assert_eq!(bin_literal("0b1111qsdf"), Ok(("qsdf", 15)));
}
#[test]
fn combinator_test2() {
for s in ["15", "0b1111", "1_5_", "0XF__", "0Xf"].iter() {
assert_eq!(expression_kind(s).unwrap().1, ExpressionKind::NatLiteral(15));
}
}
/*
#[test]
fn combinator_test3() {
let source = r#"{
4_5
11; 0xf
}"#;
let parsed = block(source).map_err(|err| match err {
Err::Error(err) | Err::Failure(err) => nom::error::convert_error(source, err),
_ => panic!()
});
//let parsed = block(source);
if let Err(err) = parsed {
println!("{}", err);
panic!("parse error desu!");
}
assert_eq!(parsed.unwrap().1, vec![
Statement { id: Default::default(), location:
Default::default(), kind: StatementKind::Expression(Expression::new(Default::default(),
ExpressionKind::NatLiteral(45))) },
Statement { id: Default::default(), location:
Default::default(), kind: StatementKind::Expression(Expression::new(Default::default(),
ExpressionKind::NatLiteral(11))) },
Statement { id: Default::default(), location:
Default::default(), kind: StatementKind::Expression(Expression::new(Default::default(),
ExpressionKind::NatLiteral(15))) },
].into());
}
*/
}