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