116 lines
2.8 KiB
Rust
116 lines
2.8 KiB
Rust
#[derive(Debug, Clone)]
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pub enum Token {
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EOF,
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Separator,
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LParen,
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RParen,
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Comma,
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Period,
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NumLiteral(f64),
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StrLiteral(String),
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Identifier(String),
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Keyword(Kw)
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}
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#[derive(Debug, Clone, PartialEq)]
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pub enum Kw {
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If,
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Then,
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Else,
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While,
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End,
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Let,
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Fn,
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Null,
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Assign
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}
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pub fn tokenize(input: &str) -> Vec<Token> {
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let mut tokens = Vec::new();
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let mut iterator = input.chars().peekable();
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fn ends_identifier(c: char) -> bool {
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match c {
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c if char::is_whitespace(c) => true,
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',' => true,
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';' => true,
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'(' => true,
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')' => true,
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'.' => true,
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_ => false
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}
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}
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while let Some(c) = iterator.next() {
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if char::is_whitespace(c) {
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continue;
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} else if c == '"' {
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let mut buffer = String::with_capacity(20);
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loop {
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match iterator.next() {
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Some(x) if x == '"' => break,
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Some(x) => buffer.push(x),
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None => return tokens,
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}
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}
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tokens.push(Token::StrLiteral(buffer));
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} else if c == '#' {
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while let Some(x) = iterator.next() {
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if x == '\n' {
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break;
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}
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}
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} else if c == ';' || c == '\n' {
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if let Some(&Token::Separator) = tokens.last() {
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} else {
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tokens.push(Token::Separator);
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}
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} else if c == '(' {
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tokens.push(Token::LParen);
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} else if c == ')' {
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tokens.push(Token::RParen);
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} else if c == ',' {
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tokens.push(Token::Comma);
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} else if c == '.' {
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tokens.push(Token::Period);
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} else {
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let mut buffer = String::with_capacity(20);
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buffer.push(c);
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while let Some(x) = iterator.peek().cloned() {
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if ends_identifier(x) {
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break;
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}
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buffer.push(iterator.next().unwrap());
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}
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match buffer.parse::<f64>() {
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Ok(f) => tokens.push(Token::NumLiteral(f)),
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_ => tokens.push(handle_identifier(buffer))
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}
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}
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}
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tokens.push(Token::EOF);
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tokens
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}
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fn handle_identifier(identifier: String) -> Token {
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let keyword = match &identifier[..] {
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"let" => Kw::Let,
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"if" => Kw::If,
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"then" => Kw::Then,
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"else" => Kw::Else,
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"while" => Kw::While,
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"end" => Kw::End,
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"fn" => Kw::Fn,
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"null" => Kw::Null,
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"=" => Kw::Assign,
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_ => return Token::Identifier(identifier)
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};
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return Token::Keyword(keyword);
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}
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