interpret.cc

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

class hold {
private:
	std::vector<hold> children;
	std::string::size_type begin, end;
	std::string quotes;
	std::string str;
	bool bigness;
public:
	hold () : hold("") {}
	hold (char *x, char *y, int start = 0) : hold(std::string(x), std::string(y), start) {}
	hold (const std::string &init, std::string quotestr = "()", std::string::size_type find = 0, bool big = true) : quotes(quotestr), bigness(big) {
	  if (quotes.size() != 2) throw "Wrong size quotestring";
	  children.reserve(init.size()/2);
	  begin = find;
	  if (init.size() != 0) {
		while (true) {
			find = init.find_first_of(quotes, big && find == 0 ? find : find + 1);
      if (init[find] == quotes[0]) {
				children.push_back(hold(init, quotestr, find, false));
				find = children.back().end;
			} else if (init[find] == quotes[1]) {
				end = find;
				if (!big || end == init.length() - 1) break;
			} else if (find == std::string::npos) {
			  break;
			} else {
				throw "Error";
			}
		}
		}
		if (!big) {
			str = init.substr(begin, end - begin);
		} else {
			str = init;
		}
	}
	std::string toFunString (std::string tab = "  ", int depth = 0) {
		std::string ret = "";
		for (int i = 0; i < depth; ++i) ret.append(tab);
		if (!bigness) ret += quotes[0];
		if (children.size() != 0) {
  		if (!bigness) ret += '\n';
			if (!bigness) depth++;
			for (auto s : children) ret.append(s.toFunString(tab, depth));
			if (!bigness) depth--;
			for (int i = 0; i < depth; ++i) ret.append(tab);
		}
		if (!bigness) ret += quotes[1];
		if (!bigness) ret += '\n';
		return ret;
	}
};

int main () {
  std::string line;
	try {
	while (true) {
	  std::cout << "> " << std::flush;
	  std::getline(std::cin, line);
	  if (line.size() == 0 || std::string("exit").find(line) == 0 || std::string("quit").find(line) == 0) break;
	  std::cout << hold(line).toFunString() << std::flush;
	  }
	} catch (const char *e) {
	  std::cerr << e << std::endl;
	  return -1;
	}
	return 0;
}