cpp-dice-roller/src/exception.cxx

//
//  exception.cxx
//  dice
//
//  Created by Sam Jaffe on 12/17/18.
//  Copyright © 2018 Sam Jaffe. All rights reserved.
//

#include "dice-roll/exception.h"

#include <cmath>
#include <string>

static std::string carrot(long long pos) {
  if (pos == -1) return "<END>"; // For safety
  std::string out;
  // resize(0) followed by back() will cause UB
  out.resize(std::max(pos, 1ll), '~');
  out.back() = '^';
  return out;
}

namespace dice {
  unexpected_token::unexpected_token(std::string const & reason, long long pos)
  : std::runtime_error(reason), position(pos) {}
  
  std::string unexpected_token::pointer(long long backup_length) const {
    return carrot(position == -1 ? backup_length : position);
  }
}