SafeOfstream.hh

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#ifndef CASM_SafeOfstream
#define CASM_SafeOfstream
 
#include <boost/filesystem.hpp>
#include <boost/filesystem/fstream.hpp>
#include <string>
#include <vector>
 
namespace CASM {
 
namespace fs = boost::filesystem;
 
//  // throws if "something.json.tmp" already exists
class SafeOfstream {
 public:
  SafeOfstream() {}
 
  void open(fs::path name, std::string tmp_ext = "tmp") {
    m_name = name;
    m_tmp_name = m_name.string() + "." + tmp_ext;
 
    if (fs::exists(m_tmp_name)) {
      throw std::runtime_error(
          std::string("Error in 'SafeOfstream::open(fs::path name, std::string "
                      "tmp_ext)'.\n") +
          "  File: " + m_tmp_name.string() + " already exists");
    }
 
    m_sout.open(m_tmp_name);
  }
 
  fs::ofstream &ofstream() { return m_sout; }
 
  void close() {
    m_sout.close();
    if (!m_sout.fail()) {
      fs::remove(m_name);
      fs::rename(m_tmp_name, m_name);
    }
  }
 
 private:
  fs::path m_name;
  fs::path m_tmp_name;
  fs::ofstream m_sout;
};
 
}  // namespace CASM
 
#endif