// Copyright Louis Delacroix 2010 - 2014.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt or copy at
// http://www.boost.org/LICENSE_1_0.txt)
//
// A pretty printing library for C++
//
// Usage:
// Include this header, and operator<< will "just work".
#ifndef H_PRETTY_PRINT
#define H_PRETTY_PRINT
#include <cstddef>
#include <iterator>
#include <memory>
#include <ostream>
#include <set>
#include <tuple>
#include <type_traits>
#include <unordered_set>
#include <utility>
#include <valarray>
namespace pretty_print
{
namespace detail
{
// SFINAE type trait to detect whether T::const_iterator exists.
struct sfinae_base
{
using yes = char;
using no = yes[2];
};
template <typename T>
struct has_const_iterator : private sfinae_base
{
private:
template <typename C> static yes & test(typename C::const_iterator*);
template <typename C> static no & test(...);
public:
static const bool value = sizeof(test<T>(nullptr)) == sizeof(yes);
using type = T;
};
template <typename T>
struct has_begin_end : private sfinae_base
{
private:
template <typename C>
static yes & f(typename std::enable_if<
std::is_same<decltype(static_cast<typename C::const_iterator(C::*)() const>(&C::begin)),
typename C::const_iterator(C::*)() const>::value>::type *);
template <typename C> static no & f(...);
template <typename C>
static yes & g(typename std::enable_if<
std::is_same<decltype(static_cast<typename C::const_iterator(C::*)() const>(&C::end)),
typename C::const_iterator(C::*)() const>::value, void>::type*);
template <typename C> static no & g(...);
public:
static bool const beg_value = sizeof(f<T>(nullptr)) == sizeof(yes);
static bool const end_value = sizeof(g<T>(nullptr)) == sizeof(yes);
};
} // namespace detail
// Holds the delimiter values for a specific character type
template <typename TChar>
struct delimiters_values
{
using char_type = TChar;
const char_type * prefix;
const char_type * delimiter;
const char_type * postfix;
};
// Defines the delimiter values for a specific container and character type
template <typename T, typename TChar>
struct delimiters
{
using type = delimiters_values<TChar>;
static const type values;
};
// Functor to print containers. You can use this directly if you want
// to specificy a non-default delimiters type. The printing logic can
// be customized by specializing the nested template.
template <typename T,
typename TChar = char,
typename TCharTraits = ::std::char_traits<TChar>,
typename TDelimiters = delimiters<T, TChar>>
struct print_container_helper
{
using delimiters_type = TDelimiters;
using ostream_type = std::basic_ostream<TChar, TCharTraits>;
template <typename U>
struct printer
{
static void print_body(const U & c, ostream_type & stream)
{
using std::begin;
using std::end;
auto it = begin(c);
const auto the_end = end(c);
if (it != the_end)
{
for ( ; ; )
{
stream << *it;
if (++it == the_end) break;
if (delimiters_type::values.delimiter != NULL)
stream << delimiters_type::values.delimiter;
}
}
}
};
print_container_helper(const T & container)
: container_(container)
{ }
inline void operator()(ostream_type & stream) const
{
if (delimiters_type::values.prefix != NULL)
stream << delimiters_type::values.prefix;
printer<T>::print_body(container_, stream);
if (delimiters_type::values.postfix != NULL)
stream << delimiters_type::values.postfix;
}
private:
const T & container_;
};
// Specialization for pairs
template <typename T, typename TChar, typename TCharTraits, typename TDelimiters>
template <typename T1, typename T2>
struct print_container_helper<T, TChar, TCharTraits, TDelimiters>::printer<std::pair<T1, T2>>
{
using ostream_type = typename print_container_helper<T, TChar, TCharTraits, TDelimiters>::ostream_type;
static void print_body(const std::pair<T1, T2> & c, ostream_type & stream)
{
stream << c.first;
if (print_container_helper<T, TChar, TCharTraits, TDelimiters>::delimiters_type::values.delimiter != NULL)
stream << print_container_helper<T, TChar, TCharTraits, TDelimiters>::delimiters_type::values.delimiter;
stream << c.second;
}
};
// Specialization for tuples
template <typename T, typename TChar, typename TCharTraits, typename TDelimiters>
template <typename ...Args>
struct print_container_helper<T, TChar, TCharTraits, TDelimiters>::printer<std::tuple<Args...>>
{
using ostream_type = typename print_container_helper<T, TChar, TCharTraits, TDelimiters>::ostream_type;
using element_type = std::tuple<Args...>;
template <std::size_t I> struct Int { };
static void print_body(const element_type & c, ostream_type & stream)
{
tuple_print(c, stream, Int<0>());
}
static void tuple_print(const element_type &, ostream_type &, Int<sizeof...(Args)>)
{
}
static void tuple_print(const element_type & c, ostream_type & stream,
typename std::conditional<sizeof...(Args) != 0, Int<0>, std::nullptr_t>::type)
{
stream << std::get<0>(c);
tuple_print(c, stream, Int<1>());
}
template <std::size_t N>
static void tuple_print(const element_type & c, ostream_type & stream, Int<N>)
{
if (print_container_helper<T, TChar, TCharTraits, TDelimiters>::delimiters_type::values.delimiter != NULL)
stream << print_container_helper<T, TChar, TCharTraits, TDelimiters>::delimiters_type::values.delimiter;
stream << std::get<N>(c);
tuple_print(c, stream, Int<N + 1>());
}
};
// Prints a print_container_helper to the specified stream.
template<typename T, typename TChar, typename TCharTraits, typename TDelimiters>
inline std::basic_ostream<TChar, TCharTraits> & operator<<(
std::basic_ostream<TChar, TCharTraits> & stream,
const print_container_helper<T, TChar, TCharTraits, TDelimiters> & helper)
{
helper(stream);
return stream;
}
// Basic is_container template; specialize to derive from std::true_type for all desired container types
template <typename T>
struct is_container : public std::integral_constant<bool,
detail::has_const_iterator<T>::value &&
detail::has_begin_end<T>::beg_value &&
detail::has_begin_end<T>::end_value> { };
template <typename T, std::size_t N>
struct is_container<T[N]> : std::true_type { };
template <std::size_t N>
struct is_container<char[N]> : std::false_type { };
template <typename T>
struct is_container<std::valarray<T>> : std::true_type { };
template <typename T1, typename T2>
struct is_container<std::pair<T1, T2>> : std::true_type { };
template <typename ...Args>
struct is_container<std::tuple<Args...>> : std::true_type { };
// Default delimiters
template <typename T> struct delimiters<T, char> { static const delimiters_values<char> values; };
template <typename T> const delimiters_values<char> delimiters<T, char>::values = { "[", ", ", "]" };
template <typename T> struct delimiters<T, wchar_t> { static const delimiters_values<wchar_t> values; };
template <typename T> const delimiters_values<wchar_t> delimiters<T, wchar_t>::values = { L"[", L", ", L"]" };
// Delimiters for (multi)set and unordered_(multi)set
template <typename T, typename TComp, typename TAllocator>
struct delimiters< ::std::set<T, TComp, TAllocator>, char> { static const delimiters_values<char> values; };
template <typename T, typename TComp, typename TAllocator>
const delimiters_values<char> delimiters< ::std::set<T, TComp, TAllocator>, char>::values = { "{", ", ", "}" };
template <typename T, typename TComp, typename TAllocator>
struct delimiters< ::std::set<T, TComp, TAllocator>, wchar_t> { static const delimiters_values<wchar_t> values; };
template <typename T, typename TComp, typename TAllocator>
const delimiters_values<wchar_t> delimiters< ::std::set<T, TComp, TAllocator>, wchar_t>::values = { L"{", L", ", L"}" };
template <typename T, typename TComp, typename TAllocator>
struct delimiters< ::std::multiset<T, TComp, TAllocator>, char> { static const delimiters_values<char> values; };
template <typename T, typename TComp, typename TAllocator>
const delimiters_values<char> delimiters< ::std::multiset<T, TComp, TAllocator>, char>::values = { "{", ", ", "}" };
template <typename T, typename TComp, typename TAllocator>
struct delimiters< ::std::multiset<T, TComp, TAllocator>, wchar_t> { static const delimiters_values<wchar_t> values; };
template <typename T, typename TComp, typename TAllocator>
const delimiters_values<wchar_t> delimiters< ::std::multiset<T, TComp, TAllocator>, wchar_t>::values = { L"{", L", ", L"}" };
template <typename T, typename THash, typename TEqual, typename TAllocator>
struct delimiters< ::std::unordered_set<T, THash, TEqual, TAllocator>, char> { static const delimiters_values<char> values; };
template <typename T, typename THash, typename TEqual, typename TAllocator>
const delimiters_values<char> delimiters< ::std::unordered_set<T, THash, TEqual, TAllocator>, char>::values = { "{", ", ", "}" };
template <typename T, typename THash, typename TEqual, typename TAllocator>
struct delimiters< ::std::unordered_set<T, THash, TEqual, TAllocator>, wchar_t> { static const delimiters_values<wchar_t> values; };
template <typename T, typename THash, typename TEqual, typename TAllocator>
const delimiters_values<wchar_t> delimiters< ::std::unordered_set<T, THash, TEqual, TAllocator>, wchar_t>::values = { L"{", L", ", L"}" };
template <typename T, typename THash, typename TEqual, typename TAllocator>
struct delimiters< ::std::unordered_multiset<T, THash, TEqual, TAllocator>, char> { static const delimiters_values<char> values; };
template <typename T, typename THash, typename TEqual, typename TAllocator>
const delimiters_values<char> delimiters< ::std::unordered_multiset<T, THash, TEqual, TAllocator>, char>::values = { "{", ", ", "}" };
template <typename T, typename THash, typename TEqual, typename TAllocator>
struct delimiters< ::std::unordered_multiset<T, THash, TEqual, TAllocator>, wchar_t> { static const delimiters_values<wchar_t> values; };
template <typename T, typename THash, typename TEqual, typename TAllocator>
const delimiters_values<wchar_t> delimiters< ::std::unordered_multiset<T, THash, TEqual, TAllocator>, wchar_t>::values = { L"{", L", ", L"}" };
// Delimiters for pair and tuple
template <typename T1, typename T2> struct delimiters<std::pair<T1, T2>, char> { static const delimiters_values<char> values; };
template <typename T1, typename T2> const delimiters_values<char> delimiters<std::pair<T1, T2>, char>::values = { "(", ", ", ")" };
template <typename T1, typename T2> struct delimiters< ::std::pair<T1, T2>, wchar_t> { static const delimiters_values<wchar_t> values; };
template <typename T1, typename T2> const delimiters_values<wchar_t> delimiters< ::std::pair<T1, T2>, wchar_t>::values = { L"(", L", ", L")" };
template <typename ...Args> struct delimiters<std::tuple<Args...>, char> { static const delimiters_values<char> values; };
template <typename ...Args> const delimiters_values<char> delimiters<std::tuple<Args...>, char>::values = { "(", ", ", ")" };
template <typename ...Args> struct delimiters< ::std::tuple<Args...>, wchar_t> { static const delimiters_values<wchar_t> values; };
template <typename ...Args> const delimiters_values<wchar_t> delimiters< ::std::tuple<Args...>, wchar_t>::values = { L"(", L", ", L")" };
// Type-erasing helper class for easy use of custom delimiters.
// Requires TCharTraits = std::char_traits<TChar> and TChar = char or wchar_t, and MyDelims needs to be defined for TChar.
// Usage: "cout << pretty_print::custom_delims<MyDelims>(x)".
struct custom_delims_base
{
virtual ~custom_delims_base() { }
virtual std::ostream & stream(::std::ostream &) = 0;
virtual std::wostream & stream(::std::wostream &) = 0;
};
template <typename T, typename Delims>
struct custom_delims_wrapper : custom_delims_base
{
custom_delims_wrapper(const T & t_) : t(t_) { }
std::ostream & stream(std::ostream & s)
{
return s << print_container_helper<T, char, std::char_traits<char>, Delims>(t);
}
std::wostream & stream(std::wostream & s)
{
return s << print_container_helper<T, wchar_t, std::char_traits<wchar_t>, Delims>(t);
}
private:
const T & t;
};
template <typename Delims>
struct custom_delims
{
template <typename Container>
custom_delims(const Container & c) : base(new custom_delims_wrapper<Container, Delims>(c)) { }
std::unique_ptr<custom_delims_base> base;
};
template <typename TChar, typename TCharTraits, typename Delims>
inline std::basic_ostream<TChar, TCharTraits> & operator<<(std::basic_ostream<TChar, TCharTraits> & s, const custom_delims<Delims> & p)
{
return p.base->stream(s);
}
// A wrapper for a C-style array given as pointer-plus-size.
// Usage: std::cout << pretty_print_array(arr, n) << std::endl;
template<typename T>
struct array_wrapper_n
{
typedef const T * const_iterator;
typedef T value_type;
array_wrapper_n(const T * const a, size_t n) : _array(a), _n(n) { }
inline const_iterator begin() const { return _array; }
inline const_iterator end() const { return _array + _n; }
private:
const T * const _array;
size_t _n;
};
// A wrapper for hash-table based containers that offer local iterators to each bucket.
// Usage: std::cout << bucket_print(m, 4) << std::endl; (Prints bucket 5 of container m.)
template <typename T>
struct bucket_print_wrapper
{
typedef typename T::const_local_iterator const_iterator;
typedef typename T::size_type size_type;
const_iterator begin() const
{
return m_map.cbegin(n);
}
const_iterator end() const
{
return m_map.cend(n);
}
bucket_print_wrapper(const T & m, size_type bucket) : m_map(m), n(bucket) { }
private:
const T & m_map;
const size_type n;
};
} // namespace pretty_print
// Global accessor functions for the convenience wrappers
template<typename T>
inline pretty_print::array_wrapper_n<T> pretty_print_array(const T * const a, size_t n)
{
return pretty_print::array_wrapper_n<T>(a, n);
}
template <typename T> pretty_print::bucket_print_wrapper<T>
bucket_print(const T & m, typename T::size_type n)
{
return pretty_print::bucket_print_wrapper<T>(m, n);
}
// Main magic entry point: An overload snuck into namespace std.
// Can we do better?
namespace std
{
// Prints a container to the stream using default delimiters
template<typename T, typename TChar, typename TCharTraits>
inline typename enable_if< ::pretty_print::is_container<T>::value,
basic_ostream<TChar, TCharTraits> &>::type
operator<<(basic_ostream<TChar, TCharTraits> & stream, const T & container)
{
return stream << ::pretty_print::print_container_helper<T, TChar, TCharTraits>(container);
}
}
#endif // H_PRETTY_PRINT
