Eryn Wells
b0b4699476
Implement structs for each state in the lexer. The State objects are responsible for determining how to handle a character and emit a Result indicating to the driver (the Lexer struct) how to proceed.
31 lines
934 B
Rust
31 lines
934 B
Rust
/* lexer/src/states/begin.rs
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* Eryn Wells <eryn@erynwells.me>
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*/
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use chars::Lexable;
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use token::Token;
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use states::{Resume, State, StateResult};
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use states::id::IdSub;
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#[derive(Debug)]
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pub struct Begin;
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impl State for Begin {
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fn lex(&mut self, c: char) -> StateResult {
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match c {
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c if c.is_left_paren() => StateResult::Emit(Token::LeftParen, Resume::AtNext),
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c if c.is_right_paren() => StateResult::Emit(Token::RightParen, Resume::AtNext),
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// TODO: Figure out some way to track newlines.
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c if c.is_whitespace() => StateResult::Continue,
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c if c.is_identifier_initial() => StateResult::Advance { to: Box::new(IdSub{}) },
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_ => {
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let msg = format!("Invalid character: {}", c);
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StateResult::Fail { msg }
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}
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}
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}
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fn none(&mut self) -> Result<Option<Token>, String> {
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Ok(None)
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}
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}
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