CmdLine.h

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#ifndef CONDTOOLS_HCAL_CMDLINE_H_
#define CONDTOOLS_HCAL_CMDLINE_H_

//=========================================================================
// CmdLine.h
//
// Simple command line parser for the C++ "main" program. It provides
// functionality of "getopt" and "getopt_long" with a convenient interface.
// Typical usage is as follows:
//
// #include <necessary standard headers>
//
// #include "CmdLine.h"
//
// using namespace cmdline;
//
// int main(int argc, char *argv[])
// {
//     CmdLine cmdline(argc, argv);
//
//     int i = 0;
//     double d = 0;
//     bool b = false;
//     std::string requiredOption;
//     std::vector<std::string> positionalArgs;
//
//     try {
//         /* Arguments are short and long versions of the option name. */
//         /* Long version can be omitted. If you want to use the long  */
//         /* version only, call the two-argument method with the short */
//         /* version set to 0.                                         */
//         cmdline.option("-i", "--integer") >> i;
//         cmdline.option("-d") >> d;
//
//         /* Options that must be present on the command line  */
//         cmdline.require("-r", "--required") >> requiredOption;
//
//         /* Switches that do not require subsequent arguments */
//         b = cmdline.has("-b");
//
//         /* Declare the end of option processing. Unconsumed options  */
//         /* will cause an exception to be thrown.                     */
//         cmdline.optend();
//
//         /* Process all remaining arguments */
//         while (cmdline)
//         {
//             std::string s;
//             cmdline >> s;
//             positionalArgs.push_back(s);
//         }
//     }
//     catch (const CmdLineError& e) {
//         std::cerr << "Error in " << cmdline.progname() << ": "
//                   << e.str() << std::endl;
//         return 1;
//     }
//
//     /* ..... Do main processing here ..... */
//
//     return 0;
// }
//
// Short version options must use a single character. It is possible
// to combine several short options together on the command line,
// for example, "-xzvf" is equivalent to "-x -z -v -f".
//
// Use standalone "-" to indicate that the next argument is either
// an option value or the program argument (but not a switch), even
// if it starts with "-". This is useful if the option value has to
// be set to a negative number.
//
// Use standalone "--" (not preceded by standalone "-") to indicate
// the end of options. All remaining arguments will be treated as
// program arguments, even if they start with "-".
//
// Note that each of the parsing methods of the CmdLine class ("option",
// "has", and "require") is greedy. These methods will consume all
// corresponding options or switches and will set the result to the last
// option value seen. It is therefore impossible to provide a collection
// of values by using an option more than once. This is done in order to
// avoid difficulties with deciding what to do when multiple option values
// were consumed by the user code only partially.
//
// After the "optend()" call, the "argc()" method of the CmdLine
// class can be used to determine the number of remaining program
// arguments. If the expected number of arguments is known in advance,
// the simplest way to get the arguments out is like this (should be
// inside the "try" block):
//
// if (cmdline.argc() != n_expected)
//     throw CmdLineError("wrong number of command line arguments");
// cmdline >> arg0 >> arg1 >> ...;
//
// I. Volobouev
// January 2016
//=========================================================================

#include <list>
#include <sstream>
#include <cstring>
#include <utility>
#include <cstdio>

#ifdef __GNUC__
#include <cstdlib>
#include <typeinfo>
#include <cxxabi.h>
#endif

#ifdef __GXX_EXPERIMENTAL_CXX0X__
#include <memory>
#define CmdLine_shared_ptr std::shared_ptr
#else
#include <tr1/memory>
#define CmdLine_shared_ptr std::tr1::shared_ptr
#endif

namespace cmdline {

  // Subsequent classes will throw exceptions of the following class
  class CmdLineError {
  public:
    inline CmdLineError(const char* msg = nullptr) : os_(new std::ostringstream()) {
      if (msg)
        *os_ << msg;
    }

    template <typename T>
    inline CmdLineError& operator<<(const T& obj) {
      *os_ << obj;
      return *this;
    }

    inline std::string str() const { return os_->str(); }

  private:
    CmdLine_shared_ptr<std::ostringstream> os_;
  };

  template <typename T>
  inline void OneShotExtract(std::istringstream& is, T& obj) {
    is >> obj;
  }

  template <>
  inline void OneShotExtract<std::string>(std::istringstream& is, std::string& obj) {
    obj = is.str();
    is.seekg(0, std::ios_base::end);
  }

  class OneShotIStream {
  public:
    inline OneShotIStream() : valid_(false), readout_(false) {}

    inline OneShotIStream(const std::string& s) : str_(s), valid_(true), readout_(false) {}

    inline operator void*() const { return valid_ && !readout_ ? (void*)this : (void*)nullptr; }

    template <typename T>
    inline bool operator>>(T& obj) {
      if (readout_)
        throw CmdLineError() << "can't reuse command line argument \"" << str_ << '"';
      readout_ = true;
      if (valid_) {
        std::istringstream is(str_);
        OneShotExtract(is, obj);
        if (is.bad() || is.fail())
          throw CmdLineError() << "failed to parse command line argument \"" << str_ << '"'
#ifdef __GNUC__
                               << ", " << demangle(obj) << " expected"
#endif
              ;
        if (is.peek() != EOF)
          throw CmdLineError() << "extra characters in command line argument \"" << str_ << '"'
#ifdef __GNUC__
                               << ", " << demangle(obj) << " expected"
#endif
              ;
      }
      return valid_;
    }

    inline bool isValid() const { return valid_; }

  private:
    std::string str_;
    bool valid_;
    bool readout_;

#ifdef __GNUC__
    template <typename T>
    inline std::string demangle(T& obj) const {
      int status;
      const std::type_info& ti = typeid(obj);
      char* realname = abi::__cxa_demangle(ti.name(), nullptr, nullptr, &status);
      std::string s(realname);
      free(realname);
      return s;
    }
#endif
  };

  class CmdLine {
    // Argument codes (second member of the pair):
    //   0 -- possible option value (or program argument, not yet known which)
    //   1 -- short option switch
    //   2 -- long option switch
    //   3 -- program argument
    typedef std::pair<std::string, int> Pair;
    typedef std::list<Pair> Optlist;

    inline Optlist::iterator find(const char* shortOpt, const char* longOpt) {
      Optlist::iterator iend = args_.end();
      for (Optlist::iterator it = args_.begin(); it != iend; ++it) {
        if (shortOpt && it->second == 1 && it->first == shortOpt)
          return it;
        if (longOpt && it->second == 2 && it->first == longOpt)
          return it;
      }
      return iend;
    }

  public:
    inline CmdLine(const unsigned argc, const char* const argv[]) : nprogargs_(0) {
      // Parse the program name
      const char* progname = std::strrchr(argv[0], '/');
      if (progname)
        ++progname;
      else
        progname = argv[0];

      // Take into account program name mangling by GNU autotools
      if (strncmp(progname, "lt-", 3) == 0)
        progname += 3;
      progname_ = progname;

      // Make a list of arguments noting on the way if this is
      // a short option, long option, or possible option argument
      bool previousIsOpt = false;
      bool nextIsArg = false;
      for (unsigned i = 1; i < argc; ++i) {
        if (nextIsArg) {
          args_.push_back(Pair(argv[i], previousIsOpt ? 0 : 3));
          previousIsOpt = false;
          ++nprogargs_;
          nextIsArg = false;
        } else if (strcmp(argv[i], "-") == 0)
          nextIsArg = true;
        else if (strcmp(argv[i], "--") == 0) {
          // End of options
          for (unsigned k = i + 1; k < argc; ++k) {
            args_.push_back(Pair(argv[k], 3));
            ++nprogargs_;
          }
          return;
        } else if (strncmp(argv[i], "--", 2) == 0) {
          args_.push_back(Pair(argv[i], 2));
          previousIsOpt = true;
        } else if (argv[i][0] == '-') {
          const unsigned len = strlen(argv[i]);
          for (unsigned k = 1; k < len; ++k) {
            std::string dummy("-");
            dummy += argv[i][k];
            args_.push_back(Pair(dummy, 1));
            previousIsOpt = true;
          }
        } else {
          args_.push_back(Pair(argv[i], previousIsOpt ? 0 : 3));
          previousIsOpt = false;
          ++nprogargs_;
        }
      }
    }

    inline const char* progname() const { return progname_.c_str(); }

    inline bool has(const char* shortOpt, const char* longOpt = nullptr) {
      bool found = false;
      for (Optlist::iterator it = find(shortOpt, longOpt); it != args_.end(); it = find(shortOpt, longOpt)) {
        found = true;
        Optlist::iterator it0(it);
        if (++it != args_.end())
          if (it->second == 0)
            it->second = 3;
        args_.erase(it0);
      }
      return found;
    }

    inline OneShotIStream option(const char* shortOpt, const char* longOpt = nullptr) {
      OneShotIStream result;
      for (Optlist::iterator it = find(shortOpt, longOpt); it != args_.end(); it = find(shortOpt, longOpt)) {
        Optlist::iterator it0(it);
        if (++it != args_.end())
          if (it->second == 0) {
            result = OneShotIStream(it->first);
            args_.erase(it0, ++it);
            --nprogargs_;
            continue;
          }
        throw CmdLineError() << "missing command line argument for option \"" << it0->first << '"';
      }
      return result;
    }

    inline OneShotIStream require(const char* shortOpt, const char* longOpt = nullptr) {
      const OneShotIStream& is(option(shortOpt, longOpt));
      if (!is.isValid()) {
        const char empty[] = "";
        const char* s = shortOpt ? shortOpt : (longOpt ? longOpt : empty);
        throw CmdLineError() << "required command line option \"" << s << "\" is missing";
      }
      return is;
    }

    inline void optend() const {
      for (Optlist::const_iterator it = args_.begin(); it != args_.end(); ++it)
        if (it->second == 1 || it->second == 2)
          throw CmdLineError("invalid command line option \"") << it->first << '"';
    }

    inline operator void*() const { return (void*)(static_cast<unsigned long>(nprogargs_)); }

    inline unsigned argc() const { return nprogargs_; }

    template <typename T>
    inline CmdLine& operator>>(T& obj) {
      if (!nprogargs_)
        throw CmdLineError("no more input available on the command line");
      Optlist::iterator it = args_.begin();
      for (; it != args_.end(); ++it)
        if (it->second == 0 || it->second == 3)
          break;
      OneShotIStream is(it->first);
      args_.erase(it);
      --nprogargs_;
      is >> obj;
      return *this;
    }

  private:
    CmdLine() = delete;

    std::string progname_;
    Optlist args_;
    unsigned nprogargs_;
  };

}  // namespace cmdline

#endif  // CONDTOOLS_HCAL_CMDLINE_H_