TParameters.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2018, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */
#pragma once
 
#include <cstdarg>
#include <cstdio>
#include <map>
#include <string>
#include <sstream>
#include <iostream>
#include <stdexcept>
#include <algorithm>  // std::max
#include <mrpt/config.h>
#include <mrpt/core/common.h>  // Disable MSVC warning 4251 in this class
 
namespace mrpt
{
namespace system
{
/** For usage when passing a dynamic number of (numeric) arguments to a
 * function, by name.
  *  \code
  *    TParameters<double> p;  // or TParametersDouble
  *    p["v_max"] = 1.0;  // Write
  *    ...
  *    cout << p["w_max"]; // Read, even if "p" was const.
  *  \endcode
  *
  *  A default list of parameters can be passed to the constructor as a sequence
  *   of pairs "name, value", which MUST end in a nullptr name string. Names
 * MUST BE "const char*"
  *   (that is, "old plain strings" are OK), not std::string objects!.
  *  See this example:
  *
  *  \code
  *    TParameters<double> p("par1",2.0, "par2",-4.5, "par3",9.0, nullptr); //
 * MUST end with a NULL
  *  \endcode
  *
  *  <b>VERY IMPORTANT:</b> If you use the NULL-ended constructor above, make
 * sure all the values are of the proper
  *    type or it will crash in runtime. For example, in a TParametersDouble all
 * values must be double's, so
  *    if you type "10" the compiler will make it an "int". Instead, write
 * "10.0".
  * \ingroup mrpt_system_grp
  * \sa the example in MRPT/samples/params-by-name
  */
template <typename T>
struct TParameters : public std::map<std::string, T>
{
        using BASE = std::map<std::string, T>;
        /** Default constructor (initializes empty) */
        TParameters() : BASE() {}
        /** Constructor with a list of initial values (see the description and use
         * example in mrpt::system::TParameters) */
        TParameters(const char* nam1, ...) : BASE()
        {
                if (!nam1) return;  // No parameters
                T val;
                va_list args;
                va_start(args, nam1);
                // 1st one out of the loop:
                val = va_arg(args, T);
                BASE::operator[](std::string(nam1)) = val;
                // Loop until NULL:
                const char* nam;
                do
                {
                        nam = va_arg(args, const char*);
                        if (nam)
                        {
                                val = va_arg(args, T);
                                BASE::operator[](std::string(nam)) = val;
                        }
                } while (nam);
                va_end(args);
        }
        inline bool has(const std::string& s) const
        {
                return std::map<std::string, T>::end() != BASE::find(s);
        }
        /** A const version of the [] operator, for usage as read-only.
          * \exception std::logic_error On parameter not present. Please, check
         * existence with "has" before reading.
          */
        inline T operator[](const std::string& s) const
        {
                typename BASE::const_iterator it = BASE::find(s);
                if (BASE::end() == it)
                        throw std::logic_error(
                                std::string("Parameter '") + s +
                                std::string("' is not present.").c_str());
                return it->second;
        }
        /** A const version of the [] operator and with a default value in case the
         * parameter is not set (for usage as read-only).
          */
        inline T getWithDefaultVal(const std::string& s, const T& defaultVal) const
        {
                typename BASE::const_iterator it = BASE::find(s);
                if (BASE::end() == it)
                        return defaultVal;
                else
                        return it->second;
        }
        /** The write (non-const) version of the [] operator. */
        inline T& operator[](const std::string& s) { return BASE::operator[](s); }
        /** Dumps to console the output from getAsString() */
        inline void dumpToConsole() const
        {
                ::fputs(getAsString().c_str(), stdout);
        }
 
        /** Returns a multi-line string representation of the parameters like : 'nam
         * = val\nnam2   = val2...' */
        inline std::string getAsString() const
        {
                std::string s;
                getAsString(s);
                return s;
        }
 
        /** Returns a multi-line string representation of the parameters like : 'nam
         * = val\nnam2   = val2...' */
        void getAsString(std::string& s) const
        {
                size_t maxStrLen = 10;
                for (const auto& e : *this)
                        maxStrLen = std::max(maxStrLen, e.first.size());
                maxStrLen++;
                std::stringstream str;
                for (const auto& e : *this)
                        str << e.first << std::string(maxStrLen - e.first.size(), ' ')
                                << " = " << e.second << std::endl;
                s = str.str();
        }
};
 
/** See the generic template mrpt::system::TParameters */
using TParametersDouble = TParameters<double>;
/** See the generic template mrpt::system::TParameters */
using TParametersString = TParameters<std::string>;
 
}  // end namespace
}