peak_icv_printable.hpp

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#pragma once
 
#include <type_traits>
#include <algorithm>
#include <ostream>
#include <sstream>
#include <string>
#include <vector>
 
namespace peak
{
namespace icv
{
namespace detail
{
 
class CommaSeperatedStream
{
public:
    explicit CommaSeperatedStream(std::ostream& os)
        : m_os(os)
    {}
 
    template <typename Type>
    CommaSeperatedStream& operator<<(const Type& value)
    {
        if (m_addDelimiter)
        {
            m_os << delimiter;
        }
        m_os << value;
        m_addDelimiter = true;
        return *this;
    }
 
    template <typename Type>
    CommaSeperatedStream& operator<<(const std::vector<Type>& vector)
    {
        if (m_addDelimiter)
        {
            m_os << delimiter;
        }
 
        m_os << "{ ";
        CommaSeperatedStream innerStream(m_os);
        std::for_each(vector.begin(), vector.end(), [&](const auto& elem) {
            innerStream << elem;
        });
        m_os << " }";
 
        m_addDelimiter = true;
        return *this;
    }
 
    CommaSeperatedStream& operator<<(std::ostream& (*manip)(std::ostream&))
    {
        m_addDelimiter = false;
        m_os << delimiter;
        m_os << manip;
        return *this;
    }
 
private:
    std::ostream& m_os;
    bool m_addDelimiter = false;
    constexpr static const char* delimiter = ", ";
};
 
// This is not real CRTP
// NOLINTBEGIN(bugprone-crtp-constructor-accessibility)
template <typename Type>
class IPrintable
{
public:
    friend std::ostream& operator<<(std::ostream& os, const Type& obj)
    {
        static_assert(std::is_base_of<IPrintable, Type>::value, "T must derive from IPrintable<T>");
 
        os << outputBegin;
        CommaSeperatedStream stream(os);
 
        auto printable = static_cast<const IPrintable<Type>*>(&obj);
        printable->Print(stream);
 
        os << outputEnd;
        return os;
    }
 
    virtual ~IPrintable() = default;
 
 
protected:
    virtual void Print(CommaSeperatedStream& stream) const = 0;
 
 
private:
    constexpr static const char* outputBegin = "{ ";
    constexpr static const char* outputEnd = " }";
};
 
template <typename BaseType>
class IterablePrinter : public IPrintable<BaseType>
{
protected:
    void Print(CommaSeperatedStream& stream) const override
    {
        PrintInternal(stream);
    }
 
private:
    template <typename...>
    using void_t = void; // std::void_t not usable before c++17
 
    template <typename Type, typename = void>
    struct has_begin : std::false_type
    {};
 
    template <typename Type>
    struct has_begin<Type, void_t<decltype(std::declval<Type>().begin())>> : std::true_type
    {};
 
    template <typename Type, typename = void>
    struct has_cbegin : std::false_type
    {};
 
    template <typename Type>
    struct has_cbegin<Type, void_t<decltype(std::declval<Type>().cbegin())>> : std::true_type
    {};
 
    template <typename Type = BaseType>
    std::enable_if_t<has_begin<Type>::value && !has_cbegin<Type>::value, void> PrintInternal(CommaSeperatedStream& stream) const
    {
        std::for_each(static_cast<const BaseType*>(this)->begin(), static_cast<const BaseType*>(this)->end(), [&](auto elem) {
            stream << elem;
        });
    }
 
    template <typename Type = BaseType>
    std::enable_if_t<has_cbegin<Type>::value, void> PrintInternal(CommaSeperatedStream& stream) const
    {
        std::for_each(static_cast<const BaseType*>(this)->cbegin(), static_cast<const BaseType*>(this)->cend(), [&](auto elem) {
            stream << elem;
        });
    }
};
 
// NOLINTEND(bugprone-crtp-constructor-accessibility)
 
} // namespace detail
} /* namespace icv */
} /* namespace peak */