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use crate::*; use derive_more::Display; use unicode_segmentation::UnicodeSegmentation; #[derive(Debug, Display, Clone)] enum LexerError { #[display(fmt = "I expected `{}`", _0)] UnexpectedToken(&'static str), } pub mod utf { use super::*; pub trait StateExt { fn peek_nth(&mut self, len: usize) -> Span; fn nth(&mut self, len: usize) -> Span; fn next(&mut self) -> Span; fn peek(&mut self, len: usize) -> Span; fn chomp(&mut self, len: usize) -> Span; fn chomp_while(&mut self, f: impl Fn(&str) -> bool) -> Span; } impl StateExt for State { fn peek_nth(&mut self, len: usize) -> Span { peek_nth(len).parse(self) } fn nth(&mut self, len: usize) -> Span { nth(len).parse(self) } fn next(&mut self) -> Span { next().parse(self) } fn peek(&mut self, len: usize) -> Span { peek(len).parse(self) } fn chomp(&mut self, len: usize) -> Span { chomp(len).parse(self) } fn chomp_while(&mut self, f: impl Fn(&str) -> bool) -> Span { chomp_while(f).parse(self) } } pub fn peek_nth(len: usize) -> impl Parser<Span> { move |state: &mut State| { let mut iter = state.input.graphemes_idx(); let (offset, len) = iter.nth(len).map(|(o, g)| (o, g.len())).unwrap_or_default(); let mut output = state.input.clone(); output.range.0 += offset; output.range.1 = len; output } } pub fn nth(len: usize) -> impl Parser<Span> { move |state: &mut State| { let output = peek_nth(len).parse(state); state.input.range.0 += output.range.0 + output.range.1; state.input.range.1 -= output.range.0 + output.range.1; output } } pub fn next() -> impl Parser<Span> { nth(0) } pub fn peek(len: usize) -> impl Parser<Span> { move |state: &mut State| { let iter = state.input.graphemes_idx(); let (offset, grapheme) = iter.take(len).last().unwrap_or_default(); let mut output = state.input.clone(); let len = offset + grapheme.len(); output.range.1 = len; output } } pub fn chomp(len: usize) -> impl Parser<Span> { move |state: &mut State| { let output = peek(len).parse(state); state.input.range.0 += output.range.1; state.input.range.1 -= output.range.1; output } } pub fn chomp_if(f: impl Fn(&str) -> bool) -> impl Parser<Span> { move |state: &mut State| { let current = peek_nth(0).parse(state); let current = match current.as_ref() { "" => return chomp(0).parse(state), c => c, }; let len = if f(current) { 1 } else { 0 }; chomp(len).parse(state) } } pub fn chomp_until(f: impl Fn(&str) -> bool) -> impl Parser<Span> { chomp_while(move |c| !f(c)) } pub fn chomp_until_eof() -> impl Parser<Span> { chomp_until(move |c| c == "") } pub fn chomp_while(f: impl Fn(&str) -> bool) -> impl Parser<Span> { move |state: &mut State| { let mut len = 0usize; loop { let current = peek_nth(len).parse(state); let current = match current.as_ref() { "" => return chomp(len).parse(state), c => c, }; let valid = f(current); if valid { len += 1; } else { return chomp(len).parse(state); } } } } #[cfg(test)] mod tests { use super::*; use test_case::test_case; const INPUT: &str = "a\u{310}e\u{301}o\u{308}\u{332}\r\n"; #[test_case(peek_nth(0), "a\u{310}", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case(peek_nth(1), "e\u{301}", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case(peek_nth(3), "\r\n", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case(peek_nth(4), "", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case(nth(0), "a\u{310}", "e\u{301}o\u{308}\u{332}\r\n")] #[test_case(nth(1), "e\u{301}", "o\u{308}\u{332}\r\n")] #[test_case(nth(3), "\r\n", "")] #[test_case(nth(4), "", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case(next(), "a\u{310}", "e\u{301}o\u{308}\u{332}\r\n")] #[test_case(peek(0), "", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case(peek(1), "a\u{310}", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case( peek(3), "a\u{310}e\u{301}o\u{308}\u{332}", "a\u{310}e\u{301}o\u{308}\u{332}\r\n" )] #[test_case( peek(99), "a\u{310}e\u{301}o\u{308}\u{332}\r\n", "a\u{310}e\u{301}o\u{308}\u{332}\r\n" )] #[test_case(chomp(0), "", "a\u{310}e\u{301}o\u{308}\u{332}\r\n")] #[test_case(chomp(1), "a\u{310}", "e\u{301}o\u{308}\u{332}\r\n")] #[test_case(chomp(3), "a\u{310}e\u{301}o\u{308}\u{332}", "\r\n")] #[test_case(chomp(99), "a\u{310}e\u{301}o\u{308}\u{332}\r\n", "")] #[test_case(chomp_while(|c| { c != "\n" && c != "\r\n" }), "a\u{310}e\u{301}o\u{308}\u{332}", "\r\n")] #[test_case(chomp_until(|c| { c == "\n" || c == "\r\n" }), "a\u{310}e\u{301}o\u{308}\u{332}", "\r\n")] fn test_parser(p: impl Parser<Span>, expected: &'static str, expected_rest: &'static str) { let mut state: State = INPUT.into(); let actual = p.parse(&mut state); assert_eq!(actual.as_ref(), expected); let rest = state.input; assert_eq!(rest.as_ref(), expected_rest); } } } impl Parser for &'static str { fn parse(&self, state: &mut State) -> Node { token(self).parse(state) } } impl Parser<Span> for &'static str { fn parse(&self, state: &mut State) -> Span { let token_len = self.graphemes(true).count(); let output = utf::peek(token_len).parse(state); match output { n if n.as_ref() == *self => utf::chomp(token_len).parse(state), _ => utf::chomp(0).parse(state), } } } pub fn token(token: &'static str) -> impl Parser { let token_len = token.graphemes(true).count(); move |state: &mut State| { let output = utf::peek(token_len).parse(state); match output { n if n.as_ref() == token => { utf::chomp(token_len).parse(state); Node::token(n) } n => raise(LexerError::UnexpectedToken(token), n.len()).parse(state), } } } pub fn recognize1( name: NodeId, parser: impl Parser<Span>, problem: impl Problem + Clone + 'static, ) -> impl Parser { move |state: &mut State| { let output = parser.parse(state); match output { result if !result.is_empty() => Node { name, span: result, children: vec![], alias: vec![], }, _ => raise(problem.clone(), 0).parse(state), } } } pub fn recognize(name: NodeId, parser: impl Parser<Span>) -> impl Parser { move |state: &mut State| { let output = parser.parse(state); match output { result if !result.is_empty() => Node { name, span: result, children: vec![], alias: vec![], }, _ => none().parse(state), } } }