Function parse_atom

docopt.cpp:350–395

static PatternList parse_expr(Tokens& tokens, std::vector<Option>& options);

static PatternList parse_atom(Tokens& tokens, std::vector<Option>& options)
{
	// atom ::= '(' expr ')' | '[' expr ']' | 'options'
	//             | long | shorts | argument | command ;

	std::string const& token = tokens.current();

	PatternList ret;

	if (token == "[") {
		tokens.pop();

		auto expr = parse_expr(tokens, options);

		auto trailing = tokens.pop();
		if (trailing != "]") {
			throw DocoptLanguageError("Mismatched '['");
		}

		ret.emplace_back(std::make_shared<Optional>(std::move(expr)));
	} else if (token=="(") {
		tokens.pop();

		auto expr = parse_expr(tokens, options);

		auto trailing = tokens.pop();
		if (trailing != ")") {
			throw DocoptLanguageError("Mismatched '('");
		}

		ret.emplace_back(std::make_shared<Required>(std::move(expr)));
	} else if (token == "options") {
		tokens.pop();
		ret.emplace_back(std::make_shared<OptionsShortcut>());
	} else if (starts_with(token, "--") && token != "--") {
		ret = parse_long(tokens, options);
	} else if (starts_with(token, "-") && token != "-" && token != "--") {
		ret = parse_short(tokens, options);
	} else if (is_argument_spec(token)) {
		ret.emplace_back(std::make_shared<Argument>(tokens.pop()));
	} else {
		ret.emplace_back(std::make_shared<Command>(tokens.pop()));
	}

	return ret;
}

static PatternList parse_seq(Tokens& tokens, std::vector<Option>& options)
{