path: root/arg_parser.c

using namespace std;
#include "arg_parser.h"
#include <complex>
#include <stdexcept>

using namespace std;

// Convert a string to this-or-that representation.
// Specialization is not the same as instantiation!
// Atox<int> and Atox<double> need to come early,
//  because they get used by later things.

template<typename T> struct cvt2 {
  static double doit(string const sss){
    stringstream parse;
    parse.str(sss);
    T rslt;
    parse >> rslt;
    if (parse.fail()) throw invalid_argument("'" + sss + "' isn't a proper " + myTraits<T>::name);
    if (parse.eof()) return rslt;
    do {
      char ch;
      parse >> ch;
      if (parse.fail()) break;
      if (ch == 'k') rslt *= 1024;
      else if (ch == 'M') rslt *= 1048576;
      else break;
      parse >> ws;        // without this, we wouldn't know whether we were at EoF
      if (!parse.eof()) break;
      return rslt;        // whew! good.
    } while (0);
    throw invalid_argument("'" + sss + "' has extraneous verbiage");
    return 0;     /* should never happen */
  }
};


template<typename T> struct helper{
  static T convert(string const &arg);
};

template<> struct helper<string> {
  static string convert(string const &arg){
    return arg;
  }
};

template<> struct helper<int> {
  static int convert(string const &arg){
    return cvt2<int>::doit(arg.c_str());
  }
};

template<> struct helper<double> {
  static double convert(string const &arg){
    if (tolower(arg) == "inf") return Inf;
    if (tolower(arg) == "-inf") return -Inf;
    return cvt2<double>::doit(arg.c_str());
  }
};

// convert to double, then downgrade to float:
template<> struct helper<float> {
  static float convert(string const &arg){
    return helper<double>::convert(arg);
  }
};

template<typename B> struct helper<vector<B> > {
  static vector<B> convert(string const &_arg){
    string arg(_arg);
    vector<B> rslt;
    while (arg.length()) {
      string::size_type where = arg.find(',');
      string word;
      if (where == arg.npos) {
        word = arg;
        arg = "";
      } else {
        word = arg.substr(0, where);
        arg = arg.substr(1+where);
      }
      rslt.push_back(helper<B>::convert(word));
    }
    return rslt;
  }
};

template<typename B>
string num_from_list(const string arg, B& rslt){
    if (arg.length()) {
      string::size_type where = arg.find_first_of(", \t");
      string word;
      if (where == arg.npos) {
        rslt = helper<B>::convert(arg);
        return "";
      } else {
        rslt = helper<B>::convert(arg.substr(0, where));
        return arg.substr(1+where);
      }
    }
// should never get here
    return arg;
}

template<typename B> struct helper<complex<B> > {
  static complex<B> convert(string const &_arg){
    string arg(_arg);
    B rp(0), ip(0);
    arg = num_from_list(arg, rp);
    arg = num_from_list(arg, ip);
    return complex<B>(rp, ip);
  }
};

// This is the interface that ordinary users use.
// The point of all this is that you can perform
// "partial specification" (what I might call re-specialization)
// on classes, but not on functions.
template <typename T>
T Atox(std::string const &str) {
  // Just delegate.
  return helper<T>::convert(str);
}

//////////////////////////////////
// Various getters.

//+++ fileGetter ....
//ordinary constructor:
  fileGetter::  fileGetter(const std::string fname){
    file.open(fname.c_str());
  }

  std::string fileGetter::get(){
    std::string str;
    for (;;) {
      file >> str;              // try to read one word
      if (file.fail()) return "";      // failed
      if (str[0] != '#') return str;    // got a comment;
      string junk;
      getline(file, junk);              //throw it away
      // go around the loop, read next line
    }
  }

// beware that neither bad() nor fail() is the opposite of good()
  int fileGetter::fail() {
    return file.fail();
  }

//+++ cmdGetter ....
//ordinary constructor:
  cmdGetter::cmdGetter(int const _argc, char const * const * _argv)
  : argc(_argc), argv(_argv), wasgood(argc) {}

  std::string cmdGetter::get(){
    if (argc <= 0) {
      wasgood = 0;
      return "";
    }
    wasgood = argc--;
    return *argv++;
  }

  int cmdGetter::fail() {
    return !wasgood;
  }

// That's all the getters for now.
//////////////////////

string tolower(const string& arg){
  string dupe(arg);
  for (string::iterator foo = dupe.begin();
            foo != dupe.end(); foo++){
    *foo = tolower(*foo);
  }
  return dupe;
}

string arg_parser::xcase(const string& arg){
    if (!fold_case) return arg;
    return tolower(arg);
}

// Constructor, for reading words from command line:
  arg_parser::arg_parser(int const _argc, char const * const * _argv)
  : fold_case(0)
  {
    std::shared_ptr<baseGetter> tmp (new cmdGetter(_argc, _argv));
    getsome.push_front(tmp);
  }

// Constructor, for reading words from file:
  arg_parser::arg_parser(const std::string fname)
  : fold_case(0), keyword("(?" "?)"), narg(0)
  {
    push(fname);
  }

  void arg_parser::push(const std::string fname){
    std::shared_ptr<baseGetter> tmp (new fileGetter(fname));
    getsome.push_front(tmp);
  }

  int arg_parser::fail(){
    if (!getsome.size()) return 1;      // is this really correct?
    return getsome.front()->fail();
  }

// see if cur arg is a prefix of patt */
int arg_parser::prefix(const string& kwpatt){
  if ((cur.length()==0 && kwpatt.length()!=0)) return 0;     // disallow "", unless exact match
  if (xcase(cur) != xcase(kwpatt).substr(0, cur.length())) return 0;
  keyword = kwpatt;
  narg = 0;
  return 1;
}

  template<class T=std::string> T arg_parser::nextRaw(){
    cur = "";
    for (;;) {
      if (!getsome.size()) {
        break;
      }
      cur += getsome.front()->get();
      if (fail()) {
        // here if read failed;  pop the context
        getsome.pop_front();
        // if read failed late;  return what we have
        if (cur.length()) return Atox<T>(cur);
        // if read failed early, try again in parent context
        continue;
      }
      size_t len = cur.length();
      if (len == 0) break;         // zero length, can't have a comma
      if (cur[len-1] != ',') break;
      // else has a comma, keep reading
    }
    return Atox<T>(cur);
  }

// return next item, assuming it is an argument:
template<class T=std::string> T arg_parser::nextArg(){
  if (0) cerr << "next called with narg: " << narg
        <<"  kw: " << keyword
        << endl;
  T rslt = nextRaw<T>();
  narg++;
  if (fail()) {
    ostringstream buf;
    buf << "Keyword " << keyword
        << " requires argument #" << narg
        << " of type " << myTraits<T>::name;
    throw invalid_argument(buf.str());
  }
  return rslt;
}

template <typename T>
arg_parser& arg_parser::operator>>(T& val){
  val = nextArg<T>();
  return *this;
}

// from .h file
//  template<typename T> T Atox(std::string const &foo);

// specializations and explicit instantiations:
// The first two lines of this macro help us figure
// out the /name/ of a type.
#define setup(T)  \
  template <> const char* myTraits<T >::name = #T;  /* specialization */   \
  template struct myTraits<T >;                     /* instantiation  */   \
  template arg_parser& arg_parser::operator>>(T& val);  \
  template T Atox<T>(std::string const &arg);           \
  template T arg_parser::nextRaw<T>();

// Last but not least, instantiate the things we are going to need.
// I don't know why the compiler can't do this automatically.
setup(int);
setup(double);
setup(float);
setup(string);
setup(vector<int>);
setup(vector<double>);
setup(complex<double>);