use super::ast::{Token, TokenKind}; use crate::syntax::text::CharStream; #[derive(Debug)] pub struct Lexer<'a> { stream: CharStream<'a>, } impl<'a> Lexer<'a> { pub fn new(text: &'a str) -> Self { Self { stream: CharStream::new(text), } } fn kind(&mut self) -> Token { fn is_type_char(c: char) -> bool { c >= 'a' && c <= 'z' || c >= 'A' && c <= 'Z' } self.stream.start_span(); self.stream.next().unwrap(); while self.stream.satifies(|c| is_type_char(*c)) { self.stream.next(); } let span = self.stream.end_span(); let kind = match span.text.to_lowercase().as_ref() { "@preamble" => TokenKind::PreambleKind, "@string" => TokenKind::StringKind, _ => TokenKind::EntryKind, }; Token::new(span, kind) } fn single_character(&mut self, kind: TokenKind) -> Token { self.stream.start_span(); self.stream.next(); let span = self.stream.end_span(); Token::new(span, kind) } fn command(&mut self) -> Token { let span = self.stream.command(); Token::new(span, TokenKind::Command) } fn word(&mut self) -> Token { fn is_word_char(c: char) -> bool { !c.is_whitespace() && c != '@' && c != '=' && c != ',' && c != '#' && c != '"' && c != '{' && c != '}' && c != '(' && c != ')' } self.stream.start_span(); while self.stream.satifies(|c| is_word_char(*c)) { self.stream.next(); } let span = self.stream.end_span(); Token::new(span, TokenKind::Word) } } impl<'a> Iterator for Lexer<'a> { type Item = Token; fn next(&mut self) -> Option { loop { match self.stream.peek() { Some('@') => return Some(self.kind()), Some('=') => return Some(self.single_character(TokenKind::Assign)), Some(',') => return Some(self.single_character(TokenKind::Comma)), Some('#') => return Some(self.single_character(TokenKind::Concat)), Some('"') => return Some(self.single_character(TokenKind::Quote)), Some('{') => return Some(self.single_character(TokenKind::BeginBrace)), Some('}') => return Some(self.single_character(TokenKind::EndBrace)), Some('(') => return Some(self.single_character(TokenKind::BeginParen)), Some(')') => return Some(self.single_character(TokenKind::EndParen)), Some('\\') => return Some(self.command()), Some(c) => { if c.is_whitespace() { self.stream.next(); } else { return Some(self.word()); } } None => { return None; } } } } } #[cfg(test)] mod tests { use super::*; use crate::{ protocol::{Position, Range}, syntax::text::Span, }; fn verify<'a>(lexer: &mut Lexer<'a>, line: u64, character: u64, text: &str, kind: TokenKind) { let start = Position::new(line, character); let end = Position::new(line, character + text.chars().count() as u64); let range = Range::new(start, end); let span = Span::new(range, text.to_owned()); let token = Token::new(span, kind); assert_eq!(Some(token), lexer.next()); } #[test] fn word() { let mut lexer = Lexer::new("foo bar baz"); verify(&mut lexer, 0, 0, "foo", TokenKind::Word); verify(&mut lexer, 0, 4, "bar", TokenKind::Word); verify(&mut lexer, 0, 8, "baz", TokenKind::Word); assert_eq!(None, lexer.next()); } #[test] fn command() { let mut lexer = Lexer::new("\\foo\\bar@baz"); verify(&mut lexer, 0, 0, "\\foo", TokenKind::Command); verify(&mut lexer, 0, 4, "\\bar@baz", TokenKind::Command); assert_eq!(None, lexer.next()); } #[test] fn escape_sequence() { let mut lexer = Lexer::new("\\foo*\n\\%\\**"); verify(&mut lexer, 0, 0, "\\foo*", TokenKind::Command); verify(&mut lexer, 1, 0, "\\%", TokenKind::Command); verify(&mut lexer, 1, 2, "\\*", TokenKind::Command); verify(&mut lexer, 1, 4, "*", TokenKind::Word); assert_eq!(None, lexer.next()); } #[test] fn delimiter() { let mut lexer = Lexer::new("{}()\""); verify(&mut lexer, 0, 0, "{", TokenKind::BeginBrace); verify(&mut lexer, 0, 1, "}", TokenKind::EndBrace); verify(&mut lexer, 0, 2, "(", TokenKind::BeginParen); verify(&mut lexer, 0, 3, ")", TokenKind::EndParen); verify(&mut lexer, 0, 4, "\"", TokenKind::Quote); assert_eq!(None, lexer.next()); } #[test] fn kind() { let mut lexer = Lexer::new("@pReAmBlE\n@article\n@string"); verify(&mut lexer, 0, 0, "@pReAmBlE", TokenKind::PreambleKind); verify(&mut lexer, 1, 0, "@article", TokenKind::EntryKind); verify(&mut lexer, 2, 0, "@string", TokenKind::StringKind); assert_eq!(None, lexer.next()); } #[test] fn operator() { let mut lexer = Lexer::new("=,#"); verify(&mut lexer, 0, 0, "=", TokenKind::Assign); verify(&mut lexer, 0, 1, ",", TokenKind::Comma); verify(&mut lexer, 0, 2, "#", TokenKind::Concat); assert_eq!(None, lexer.next()); } }