ClickHouse/dbms/src/Common/Macros.cpp

#include <DB/Common/Macros.h>
#include <DB/Core/Exception.h>
#include <DB/Core/ErrorCodes.h>

namespace DB
{

Macros::Macros() {}

Macros::Macros(const Poco::Util::AbstractConfiguration & config, const String & root_key)
{
	Poco::Util::AbstractConfiguration::Keys keys;
	config.keys(root_key, keys);
	for (const String & key : keys)
	{
		macros[key] = config.getString(root_key + "." + key);
	}
}

String Macros::expand(const String & s, size_t level) const
{
	if (s.find('{') == String::npos)
		return s;

	if (level && s.size() > 65536)
		throw Exception("Too long string while expanding macros", ErrorCodes::SYNTAX_ERROR);

	if (level >= 10)
		throw Exception("Too deep recursion while expanding macros: '" + s + "'", ErrorCodes::SYNTAX_ERROR);

	String res;
	size_t pos = 0;
	while (true)
	{
		size_t begin = s.find('{', pos);

		if (begin == String::npos)
		{
			res.append(s, pos, String::npos);
			break;
		}
		else
		{
			res.append(s, pos, begin - pos);
		}

		++begin;
		size_t end = s.find('}', begin);
		if (end == String::npos)
			throw Exception("Unbalanced { and } in string with macros: '" + s + "'", ErrorCodes::SYNTAX_ERROR);

		String macro_name = s.substr(begin, end - begin);

		auto it = macros.find(macro_name);
		if (it == macros.end())
			throw Exception("No macro " + macro_name + " in config", ErrorCodes::SYNTAX_ERROR);

		res += it->second;

		pos = end + 1;
	}

	return expand(res, level + 1);
}

}