Improved scientific notation parsing for lexer

gistfile0.txt

// Handle scientific notation (e.g., 1.23e45 or 1e-10)
} else if grapheme == "e" || grapheme == "E" {
    if is_scientific {
        self.errors.push(LexError::new(
            graphemes.concat(),
            self.line,
            self.column,
            "number may not contain multiple exponential parts".to_owned(),
        ));
        return;
    }
    
    // Mark as float and scientific notation
    is_float = true;
    is_scientific = true;
    number.push_str(grapheme);
    self.column += 1;
    
    // Check for end of input
    if self.column > graphemes.len() {
        self.errors.push(LexError::new(
            graphemes.concat(),
            self.line,
            self.column - 1,
            "expected digits after 'e'".to_owned(),
        ));
        return;
    }
    
    // Handle optional sign
    if graphemes[self.column - 1] == "+" || graphemes[self.column - 1] == "-" {
        number.push_str(graphemes[self.column - 1]);
        self.column += 1;
        
        // Check again for end of input after sign
        if self.column > graphemes.len() {
            self.errors.push(LexError::new(
                graphemes.concat(),
                self.line,
                self.column - 1,
                "expected digits after exponent sign".to_owned(),
            ));
            return;
        }
    }
    
    // Ensure we have at least one digit in the exponent
    if self.column <= graphemes.len() 
        && graphemes[self.column - 1].chars().next().unwrap_or('\0').is_ascii_digit() 
    {
        // Consume the first digit
        number.push_str(graphemes[self.column - 1]);
        self.column += 1;
        
        // Now continue in the next loop iteration to consume any additional exponent digits
        // (they'll be handled by the main digit-consuming case at the top of the loop)
    } else {
        self.errors.push(LexError::new(
            graphemes.concat(),
            self.line,
            self.column - 1,
            "expected at least one digit in exponent".to_owned(),
        ));
        return;
    }
}
EOF < /dev/null