https://repl.it/CYSv/30 created by xaliphostes

Command args.cpp

/**
 * ------------------------------------------------------------
 * Show how convenient it is to use classes instead of a bunch
 * of C functions.
 *
 * Part of the OOP course for PhD students and Researchers.
 *
 * Contact: fmaerten@gmail.com
 * ------------------------------------------------------------
 */
 
#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std ;

/**
 * @brief A convenient class which help to analyse arguments passed to a command-line.
 *        An argument starts with a minus (a switch), the next argument is either its
 *        value or a next switch.
 * @note  We didn't put any comment in the class as it is self explanatory.
 * @note  Public are first since this is what we are interested in (client code).
 *        Private methods and members follow as they are useless for us.
 * @note  Note how public methods are indented for a better reading of the return 
 *        type and the arguments.
 * @note  It is better to write the implementation elsewhere, even if it requires more
 *        writting...That way, the class interface is more simple, less overloaded and
 *        more clear.
 */
class Args {
public:
  Args(const string& argv) ;
  
  bool           exists  (const string& name) const ;
  bool           hasValue(const string& name) const ;
  string         value   (const string& name) const ;
  vector<string> switches() const ;
  void           display () const ;
  
private:
  vector<string> split(const string& str, int delimiter(int) = ::isspace) ;
	int            index(const string& name) const ;
	string         argv_ ;
	vector<string> toks_ ;
} ;

// -----------------------------------------------------------------------------------

// A convenient function for testing
//
void check(const Args& a, const string& name) {
	if (a.exists(name)) {
  	cerr << "switch '" << name << "' exists with value " << a.value(name) << endl ;
  } else {
  	cerr << "switch '" << name << "' does not exist!" << endl ;
  }
}

// -----------------------------------------------------------------------------------

int main(int argc, char** argv) {
  Args a("-aux 23 -u toto -tol 1e-8 -c -o aaa -name \"filename.txt\" -j") ;
  cerr << "---------------------------------" << endl ;
  
  check(a, "tol") ;
  cerr << "---------------------------------" << endl ;
  
  check(a, "epsilon") ;
  cerr << "---------------------------------" << endl ;
  
  vector<string> switches = a.switches() ;
  cerr << "List of switches:" << endl ;
  for (const string& s : switches) {
  	if (a.hasValue(s))
  		cerr << "  [" << s << "] has value [" << a.value(s) << "]" << endl ;
  	else
  		cerr << "  [" << s << "]" << endl ;
  }
  cerr << "---------------------------------" << endl ;
}




















// ================== IMPL ==================================================

Args::Args(const string& argv): argv_(argv) {
	toks_ = split(argv) ;
}
  
bool Args::exists(const string& name) const {
  return index(name) !=-1 ;
}

string Args::value(const string& name) const {
	int i = index(name) ;
	if (i==-1) {
		return "" ;
	}
	if (i>=toks_.size()-1) {
		return "" ;
	}
	return toks_[i+1] ;
}

bool Args::hasValue(const string& name) const {
	int i = index(name) ;
	if (i==-1) {
		return false ;
	}
	if (i>=toks_.size()-1) {
		return false ;
	}
	if (toks_[i+1][0]=='-') {
		return false ;
	}
	return true ;
}

vector<string> Args::switches() const {
	vector<string> s ;
	for (int i=0; i<toks_.size(); ++i) {
		if (toks_[i][0]=='-') {
			s.push_back(toks_[i].substr(1,string::npos)) ;
		}
	}
	return s ;
}

void Args::display () const {
	for (int i=0; i<toks_.size(); ++i) {
		if (toks_[i][0]=='-') {
			cerr << toks_[i].substr(1,string::npos) ;
			if (i<toks_.size()-1 && toks_[i+1][0]!='-') {
				cerr << "\t" << toks_[i+1] ;
				i++ ;
			}
			cerr << endl ;
		}
	}
}

// private

vector<string> Args::split(const string& str, int delimiter(int)) {
	vector<string> result ;
	auto e=str.end() ;
	auto i=str.begin() ;
	while(i!=e) {
  		i = find_if_not(i,e, delimiter) ;
  		if (i==e) {
			break ;
		}
  		auto j = find_if(i,e, delimiter) ;
  		result.push_back(string(i,j)) ;
  		i = j ;
  	}
	return result ;
}

int Args::index(const string& name) const {
	for (int i=0; i<toks_.size(); ++i) {
		if (toks_[i][0]=='-') {
			if (toks_[i].substr(1,string::npos)==name) {
				return i ;
			}
		}
	}
	return -1 ;
}

Command args_console_dump.txt

gcc version 4.6.3
Command launched:
args -aux 23 -u toto -tol 1e-8 -c -o aaa -name "filename.txt" -j


>>> ---------------------------------
switch 'tol' exists with value 1e-8
---------------------------------
switch 'epsilon' does not exist!
---------------------------------
List of switches:
  [aux] has value [23]
  [u] has value [toto]
  [tol] has value [1e-8]
  [c]
  [o] has value [aaa]
  [name] has value ["filename.txt"]
  [j]
---------------------------------