76 lines
No EOL
2.2 KiB
Rust
76 lines
No EOL
2.2 KiB
Rust
use crate::token::Token;
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pub struct Lexer {
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source: Vec<u8>,
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pos: usize
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}
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impl Lexer {
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pub fn new(source: &str) -> Self {
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Self {
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source: source.as_bytes().to_vec(),
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pos: 0
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}
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}
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fn skip_whitespace(&mut self) {
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while matches!(self.peek(), Some(c) if c.is_ascii_whitespace()) {
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self.advance();
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}
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}
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fn advance(&mut self) {
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self.pos += 1;
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}
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fn peek(&self) -> Option<u8> {
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self.source.get(self.pos).copied()
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}
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fn number(&mut self) -> Option<Token> {
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let mut num = String::new();
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while matches!(self.peek(), Some(b'0' ..= b'9')) {
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num.push(self.peek().unwrap() as char);
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self.advance();
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}
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Some(Token::Number(num.parse().unwrap()))
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}
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fn ident(&mut self) -> Option<Token> {
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let mut ident = String::new();
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while matches!(self.peek(), Some(b'a' ..= b'z' | b'A' ..= b'Z')) {
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ident.push(self.peek().unwrap() as char);
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}
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Some(Token::Ident(ident))
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}
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pub fn next(&mut self) -> Option<Token> {
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self.skip_whitespace();
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match self.peek() {
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Some(b'0' ..= b'9') => self.number(),
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Some(b'a' ..= b'z' | b'A' ..= b'Z') => self.ident(),
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Some(b'+') => {self.advance(); Some(Token::Plus)},
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Some(b'-') => {self.advance(); Some(Token::Minus)},
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Some(b'*') => {self.advance(); Some(Token::Asterisk)},
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Some(b'/') => {self.advance(); Some(Token::Slash)},
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Some(b'%') => {self.advance(); Some(Token::Percent)},
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Some(b'^') => {self.advance(); Some(Token::Caret)},
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Some(b'(') => {self.advance(); Some(Token::LParen)},
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Some(b')') => {self.advance(); Some(Token::RParen)},
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Some(b'[') => {self.advance(); Some(Token::LBracket)},
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Some(b']') => {self.advance(); Some(Token::RBracket)},
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Some(b'{') => {self.advance(); Some(Token::LBrace)},
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Some(b'}') => {self.advance(); Some(Token::RBrace)},
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Some(b';') => {self.advance(); Some(Token::Semicolon)}
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_ => None
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}
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}
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} |