tokenizer.cpp

#include <error.h>
#include <tokenizer.h>

void Tokenizer::Next() {
    char cur_char = '\0';
    while (in_->get(cur_char)) {
        if (!std::isspace(cur_char)) {
            break;
        }
    }

    if (in_->eof()) {
        is_end_ = true;
        cur_token_ = std::nullopt;
        return;
    }

    if (cur_char == '\'') {
        cur_token_ = QuoteToken();
        return;
    }

    if (cur_char == '.') {
        cur_token_ = DotToken();
        return;
    }

    if (cur_char == '(') {
        cur_token_ = BracketToken::OPEN;
        return;
    }

    if (cur_char == ')') {
        cur_token_ = BracketToken::CLOSE;
        return;
    }

    if (cur_char == '+' || cur_char == '-') {
        if (std::isdigit(in_->peek())) {
            in_->unget();

            int value;
            *in_ >> value;
            cur_token_ = ConstantToken(value);
        } else {
            cur_token_ = SymbolToken(std::string({cur_char}));
        }
        return;
    }

    if (std::isdigit(cur_char)) {
        in_->unget();

        int value;
        *in_ >> value;
        cur_token_ = ConstantToken(value);
        return;
    }

    if (cur_char == '#') {
        char next_char = in_->get();
        if (next_char == 't') {
            cur_token_ = BooleanToken(true);
        } else if (next_char == 'f') {
            cur_token_ = BooleanToken(false);
        } else {
            throw SyntaxError("Unexpected symbol");
        }
        return;
    }

    const std::string valid_start_symbols = "<=>*/#";
    const std::string valid_symbols = valid_start_symbols + "?!-";
    if (std::isalpha(cur_char) || valid_start_symbols.find(cur_char) != std::string::npos) {
        std::string name{cur_char};
        while (std::isalpha(in_->peek()) || std::isdigit(in_->peek()) ||
               valid_symbols.find(in_->peek()) != std::string::npos) {
            name += in_->get();
        }
        cur_token_ = SymbolToken(name);
        return;
    }

    throw SyntaxError("Unexpected symbol");
}