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Slightly refactor lexer

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This commit is contained in:
Daniel M 2022-01-29 21:59:48 +01:00
parent b7872da3ea
commit 39351e1131
1 changed files with 22 additions and 19 deletions
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41
src/lexer.rs
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@ -81,25 +81,28 @@ impl<'a> Lexer<'a> {
fn lex(&mut self) -> Vec<Token> { fn lex(&mut self) -> Vec<Token> {
let mut tokens = Vec::new(); let mut tokens = Vec::new();
while let Some(ch) = self.next() { loop {
match ch { match self.next() {
// Skip whitespace // Skip whitespace
' ' => (), ' ' | '\t' => (),
// Stop lexing at EOF
'\0' => break,
// Lex numbers // Lex numbers
'0'..='9' => { ch @ '0'..='9' => {
let mut sval = String::from(ch); let mut sval = String::from(ch);
// Do as long as a next char exists and it is a numeric char // Do as long as a next char exists and it is a numeric char
while let Some(ch) = self.peek() { loop {
// The next char is verified to be Some, so unwrap is safe // The next char is verified to be Some, so unwrap is safe
match ch { match self.peek() {
// Underscore is a separator, so remove it but don't add to number // Underscore is a separator, so remove it but don't add to number
'_' => { '_' => {
self.next().unwrap(); self.next();
} }
'0'..='9' => { '0'..='9' => {
sval.push(self.next().unwrap()); sval.push(self.next());
} }
// Next char is not a number, so stop and finish the number token // Next char is not a number, so stop and finish the number token
_ => break, _ => break,
@ -110,27 +113,27 @@ impl<'a> Lexer<'a> {
tokens.push(Token::I64(sval.parse().unwrap())); tokens.push(Token::I64(sval.parse().unwrap()));
} }
'>' if matches!(self.peek(), Some('>')) => { '>' if matches!(self.peek(), '>') => {
self.next(); self.next();
tokens.push(Token::Shr); tokens.push(Token::Shr);
} }
'<' if matches!(self.peek(), Some('<')) => { '<' if matches!(self.peek(), '<') => {
self.next(); self.next();
tokens.push(Token::Shl); tokens.push(Token::Shl);
} }
'=' if matches!(self.peek(), Some('=')) => { '=' if matches!(self.peek(), '=') => {
self.next(); self.next();
tokens.push(Token::EquEqu); tokens.push(Token::EquEqu);
} }
'!' if matches!(self.peek(), Some('=')) => { '!' if matches!(self.peek(), '=') => {
self.next(); self.next();
tokens.push(Token::NotEqu); tokens.push(Token::NotEqu);
} }
'<' if matches!(self.peek(), Some('=')) => { '<' if matches!(self.peek(), '=') => {
self.next(); self.next();
tokens.push(Token::LAngleEqu); tokens.push(Token::LAngleEqu);
} }
'>' if matches!(self.peek(), Some('=')) => { '>' if matches!(self.peek(), '=') => {
self.next(); self.next();
tokens.push(Token::RAngleEqu); tokens.push(Token::RAngleEqu);
} }
@ -150,7 +153,7 @@ impl<'a> Lexer<'a> {
'>' => tokens.push(Token::RAngle), '>' => tokens.push(Token::RAngle),
//TODO: Don't panic, keep calm //TODO: Don't panic, keep calm
_ => panic!("Lexer encountered unexpected char: '{}'", ch), ch => panic!("Lexer encountered unexpected char: '{}'", ch),
} }
} }
@ -158,13 +161,13 @@ impl<'a> Lexer<'a> {
} }
/// Advance to next character and return the removed char /// Advance to next character and return the removed char
fn next(&mut self) -> Option<char> { fn next(&mut self) -> char {
self.code.next() self.code.next().unwrap_or('\0')
} }
/// Get the next character without removing it /// Get the next character without removing it
fn peek(&mut self) -> Option<char> { fn peek(&mut self) -> char {
self.code.peek().copied() self.code.peek().copied().unwrap_or('\0')
} }
} }