gmt-makemap/modules/gmt/modgmt_param.h

#ifndef MODGMT_PARAM_H
#define MODGMT_PARAM_H
#include "modgmt_strcomp.h"
#include "common.h"

// Common ancestor for all parameters
template<class Converter, bool Optional>
class Parameter
{
 using ValueType=typename Converter::ValueType;
 std::string name; // Used for error reporting
 bool initialised;
 Converter conv;
 ValueType val;

 template<bool hasDefault, class Conv=Converter>
 struct Adapter;
 template<class Conv>
 struct Adapter<true,Conv> {static const typename Conv::ValueType& Val(const Conv& cnv) {return cnv.Default();}};
 template<class Conv>
 struct Adapter<false,Conv> {static typename Conv::ValueType Val(const Conv& cnv) {return typename Conv::ValueType();}};

 template<class C>
 struct CheckDefault
 {
  private:
  static void detect(...);
  template<class T> static decltype(std::declval<T>().Default()) detect(T);
  public:
  static constexpr bool value=std::is_same<ValueType, typename std::decay<decltype(detect(std::declval<C>()))>::type>::value;
 };

 protected:
 Parameter(Parameter&&) = delete;
 Parameter(const Parameter&) = delete;
 Parameter() = delete;

 template<class... Args>
 Parameter(std::string&& str, Args... args): name(std::move(str)), initialised(false), conv(args...)
 {
  val=Adapter<CheckDefault<Converter>::value>::Val(conv);
 }
 template<class... Args>
 Parameter(const std::string& str, Args... args): name(str), initialised(false), conv(args...)
 {
  val=Adapter<CheckDefault<Converter>::value>::Val(conv);
 }

 void SetState(bool newini) {initialised=newini;}

 public:
 bool Init(const ObjectBase* p, std::string& err)
 {
  std::string cerr;
  bool res=true;
  ValueType tval=conv.Convert(p,&res,cerr);
  SetState(res);
  if(res) val=std::move(tval);
  else err=std::move(cerr);
  return res;
 }
 bool Initialised() const {return initialised;}
 bool Exist() const {return initialised;}
 const std::string& Name() const {return name;}
 constexpr bool isOptional() const {return Optional;}
 const ValueType& Value() {return val;}
 const ValueType* operator->() const {return &val;}
 operator const ValueType&() {return val;}
 void Reset() {initialised=false; val=std::move(Adapter<CheckDefault<Converter>::value>::Val(conv));}

 static constexpr bool optional=Optional;
 using ConverterType=Converter;
};


// Class for parameter which must be in named pair
template <class Converter, bool O>
class NamedParameter: public TemplateComparator, public Parameter<Converter,O>
{
 public:
 using AcceptableObject=void;
 template<class... Args>
 NamedParameter(const std::string& t, Args... args):TemplateComparator(t),Parameter<Converter,O>(Template2Name(),args...) {}
};


// Class for parameter which can be in named pair or as object of type Object
template <class Converter, bool O, class Object>
class NamedFreeParameter: public NamedParameter<Converter,O>
{
 public:
 using AcceptableObject=Object;
 template<class... Args>
 NamedFreeParameter(Args... args):NamedParameter<Converter,O>(args...) {}
};

// Class for parameter which can be in some positions in list
template <class Converter, bool O>
class PositionalParameter: public Parameter<Converter,O>
{
 public:
 template<class... Args>
 PositionalParameter(Args... args):Parameter<Converter,O>(args...) {}
};


// Base class for ParseNamedParameters and ParsePositionalParameters
class ParseParameters
{
 protected:
 std::string err;
 ParseParameters():err() {}
 ParseParameters(const ParseParameters&) = delete;
 ParseParameters(ParseParameters&&) = delete;

 public:
 std::string Error() const {return err;}
 bool Ok() const {return err.empty();}
 operator bool() const {return Ok();}
};

// Parsing positional parameters
class ParsePositionalParameters: public ParseParameters
{
 ParsePositionalParameters() = delete;
 ParsePositionalParameters(const ParsePositionalParameters&) = delete;
 ParsePositionalParameters(ParsePositionalParameters&&) = delete;

 // Main parsing function
 template <class Par, class... Args>
 void Parse(ObjectList::IndexType i, const ObjectList* ol, Par& param, Args&... args)
 {
  // Check types of arguments
  static_assert(std::is_same<PositionalParameter<typename Par::ConverterType, Par::optional>,Par>::value,"ParsePositionalParameters argument(s) must be PositionalParameter");

  // Check if parameter already initialised. This is code error.
  if(param.Initialised())
  {
   err="Parameter "+param.Name()+" already initialised. This is code error.";
   return;
  }

  // List is ended
  if(i>=ol->Size())
  {
   // Parameter is optional, skip it
   if(Par::optional) Parse(i,ol,args...);
   // Parameter is required, this is an error
   else err="Parameter "+param.Name()+" is required, but can't be setted because list is ended";
  }
  // Initialise from some list element
  else
  {
   bool res=param.Init(ol->At(i),err);
   // All Ok, continue to next element in list
   if(res) Parse(i+1,ol,args...);
   else
   {
    // All Ok, optional parameter may be absent, try to initialise next parameter by same list element
    if(Par::optional) Parse(i,ol,args...);
    // Error, required parameter not initialised
    else err="Can't initialise parameter "+param.Name()+" from list element number "+ToString(i)+": "+err;
   }
  }
 }
 // Bottom of recursion
 void Parse(ObjectList::IndexType i, const ObjectList* ol) {if(i<ol->Size()) err="There are excess elements in list";}

 public:
 template <class... Args>
 ParsePositionalParameters(const ObjectList* ol, Args&... args) {Parse(0,ol,args...);}
};


// Parsing named parameters
class ParseNamedParameters: public ParseParameters
{
 ParseNamedParameters() = delete;
 ParseNamedParameters(const ParseNamedParameters&) = delete;
 ParseNamedParameters(ParseNamedParameters&&) = delete;

 // Parsing function for elements without names
 // ob - object from which we initialise parameter param.
 // init - is ob was already used for initialise something.
 // args - other parameters
 // Function try to initialise parameter param, if param accepted real type of ob for initialisation, else function try to initialise next parameter in args.
 // Function return error if initialisation of parameter failed or if two parameters can be initialised from ob.
 template <class Par, class... Args>
 bool ParseSingle(const ObjectBase* ob, bool init, Par& param, Args&... args)
 {
  // Check types of arguments
  static_assert(std::is_same<NamedParameter<typename Par::ConverterType, Par::optional>,Par>::value || std::is_same<NamedFreeParameter<typename Par::ConverterType, Par::optional, typename Par::AcceptableObject>,Par>::value,"ParseNamedParameters argument(s) must be NamedParameter or NamedFreeParameter");

  OBType<typename Par::AcceptableObject> o(ob);
  if(o && init)
  {
   err="Object of type "+ob->Type()+" used for initialisation of two parameters. This is code error.";
   return false;
  }
  if(!o) return ParseSingle(ob,init,args...); // Type mismatch, goto next parameter
  if(param.Initialised())
  {
   err="Parameter "+param.Name()+" can't be initialised from object of type "+ob->Type()+" because it already initialised.";
   return false;
  }
  std::string ierr;
  if(!param.Init(ob,ierr))
  {
   err="Parameter "+param.Name()+" can't be initialised from object of type "+ob->Type()+": "+ierr;
   return false;
  }
  return ParseSingle(ob,true,args...);
 }
 // Bottom of recursion
 bool ParseSingle(const ObjectBase* ob, bool init) const {return true;}

 // Parsing function for elements in pairs
 // op - pair from which we initialise parameter param.
 // pname - name of parameter already initialised from op (or empty string).
 // args - other parameters
 // Function try to initialise parameter param, if pair name corresponding to param template, else function try to initialise next parameter in args.
 // Function return error if initialisation of parameter failed or if two parameters can be initialised from op.
 template <class Par, class... Args>
 bool ParsePair(const ObjectPair* op, std::string& pname, Par& param, Args&... args)
 {
  // Check types of arguments
  static_assert(std::is_same<NamedParameter<typename Par::ConverterType, Par::optional>,Par>::value || std::is_same<NamedFreeParameter<typename Par::ConverterType, Par::optional, typename Par::AcceptableObject>,Par>::value,"ParseNamedParameters argument(s) must be NamedParameter or NamedFreeParameter");

  bool cmp=param.Compare(op->Name());
  if(cmp && !pname.empty())
  {
   err="Element "+op->Name()+" can be used for initialisation of two parameters: "+pname+" and "+param.Name();
   return false;
  }
  if(!cmp) return ParsePair(op,pname,args...); // Name mismatch, goto next parameter
  pname=param.Name();
  if(param.Initialised())
  {
   err="Parameter "+param.Name()+" can't be initialised from element "+op->Name()+" because it already initialised.";
   return false;
  }
  std::string ierr;
  if(!param.Init(op->Value(),ierr))
  {
   err="Parameter "+param.Name()+" can't be initialised from element "+op->Name()+": "+ierr;
   return false;
  }
  return ParsePair(op,pname,args...);
 }
 // Bottom of recursion
 bool ParsePair(const ObjectPair* op, std::string& pname) const {return true;}

 template <class Par, class... Args>
 void CheckRequired(const Par& param, Args&... args)
 {
  if((Par::optional || param.Initialised())) CheckRequired(args...);
  else err="Parameter "+param.Name()+" is required, but not initialised";
 }
 // Bottom of recursion
 void CheckRequired() const {}

 public:
 template <class... Args>
 ParseNamedParameters(const ObjectList* ol, Args&... args)
 {
  // Initialisation
  std::string pname;
  for(ObjectList::const_iterator i=ol->begin();i!=ol->end();++i)
  {
   pname.erase();
   OBType<ObjectPair> p(*i);
   if( !(p?ParsePair(p,pname,args...):ParseSingle(*i,false,args...)) ) break;
  }
  if(!Ok()) return; // Error on initialisation phase
  // Check if all required parameters are initialised
  CheckRequired(args...);
 }
};

template<class Converter>
using ONPar=NamedParameter<Converter,true>;
template<class Converter>
using RNPar=NamedParameter<Converter,false>;

template<class Converter, class Object>
using ONFPar=NamedFreeParameter<Converter,true,Object>;
template<class Converter, class Object>
using RNFPar=NamedFreeParameter<Converter,false,Object>;

template<class Converter>
using OPosPar=PositionalParameter<Converter,true>;
template<class Converter>
using RPosPar=PositionalParameter<Converter,false>;

#endif