Patterns::Tools Namespace Reference

Classes
struct	Convert

Functions
template<typename T >
std::string	to_string (const T &t)
template<typename T >
void	to_value (const std::string &s, T &t)
static ::ExceptionBase &	ExcNoMatch (std::string arg1, const Patterns::PatternBase *arg2)

Detailed Description

Namespace for a few classes and functions that act on values and patterns, and allow to convert from non elementary types to strings and vice versa.

A typical usage of these tools is in the following example:

using T = std::vector<unsigned int>;

T vec(3);
vec[0] = 1;
vec[1] = 3;
vec[2] = 5;

auto pattern = Patterns::Tools::Convert<T>::to_pattern();

std::cout << pattern->description() << std::endl;
// [List of <[Integer]> of length 0...4294967295 (inclusive)]

auto s = Patterns::Tools::Convert<T>::to_string(vec);
std::cout << s << std::endl;
// 1, 2, 3

auto vec = Patterns::Tools::Convert<T>::to_value("2,3,4,5");
// now vec has size 4, and contains the elements 2,3,4,5

std::cout << internal::RankInfo<T>::list_rank << std::endl; // Outputs 1
std::cout << internal::RankInfo<T>::map_rank  << std::endl; // Outputs 0

Convert<T> is used by the function Patterns::Tools::add_parameter() in this namespace. Internally it uses the internal::RankInfo<T> class to decide how many different separators are required to convert the given type to a string.

For example, to write vectors of vectors, the default is to use "," for the first (inner) separator, and ";" for the second (outer) separator, i.e.

std::vector<std::vector<unsigned int>> vec;
vec = Convert<decltype(vec)>::to_value("1,2,3 ; 4,5,6");

s = convert<decltype(vec[0])>::to_string(vec[0]);
// s now contains the string "1,2,3"

Separators for Patterns::List and Patterns::Map compatible types are selected according to the rank of the list and map objects, using the arrays Patterns::Tools::internal::default_list_separator and Patterns::Tools::internal::default_map_separator.

They are currently set to:

default_list_separator{{","  ,  ";"  ,  "|"  ,   "%"}};
default_map_separator {{":"  ,  "="  ,  "@"  ,   "#"}};

When one needs a mixture of Patterns::List and Patterns::Map types, their RankInfo is computed by taking the maximum of the vector_rank of the Key and of the Value type, so that, for example, it is possible to have the following

... // Build compare class
std::map<std::vector<unsigned int>, std::vector<double>, compare> map;

map = convert<decltype(map)>::to_value(
  "1,2,3 : 5.0,6.0,7.0  ; 8,9,10 : 11.0,12.0,13.0");

Some non elementary types are supported, like Point(), or std::complex<double>. If you wish to support more types, you have to specialize the Convert struct as well as the RankInfo struct.

Author

Luca Heltai, 2017

Function Documentation

to_string()

template<typename T >

std::string Patterns::Tools::to_string

(

const T &

t

)

A utility function that simplifies the conversion to strings of arbitrarily complex types.

This function calls the method Convert<T>::to_string() with the default pattern. An example usage is the following:

auto t = std::make_tuple(1.0, std::make_pair(1, "ciao"));
auto s = Patterns::Tools::to_string(t);

std::cout << s; // will print "1 % 1 : ciao""

See the documentation of the class Patterns::Tools::Convert, and of the helper class Patterns::Tools::RankInfo for details on the way separators are selected when outputting STL container types.

Author

Luca Heltai, 2018

Definition at line 2363 of file patterns.h.

to_value()

template<typename T >

void Patterns::Tools::to_value	(	const std::string &	s,
		T &	t
	)

A utility function that simplifies the conversion from strings to arbitrary types.

This function calls the method Convert<T>::to_value() with the default pattern. An example usage is the following:

auto t = std::make_tuple(1.0, std::make_pair(1, "ciao"));
// replace the value of 't' by the parsed content of the string argument:
Patterns::Tools::to_value("2 % 3 : mondo", t);

auto s = Patterns::Tools::to_string(t);
std::cout << s; // will print "2 % 3 : mondo""

See the documentation of the class Patterns::Tools::Convert, and of the helper class Patterns::Tools::RankInfo for details on the separators you should use in your string patterns when converting from a string to a container type.

Notice that the current content of variable t is ignored. Its type is used to infer how to interpret the string. If the string is successfully parsed, then t will be set to the parsed content of s.

Author

Luca Heltai, 2018

Definition at line 2371 of file patterns.h.