formatters.h

// Copyright 2026 Julien Michot.
// SPDX-License-Identifier: Apache-2.0
 
#pragma once
 
#include <format>
#include <sstream>
 
#include <tinyopt/math.h>
 
#ifdef TINYOPT_FORMAT_NS
 
#include <tinyopt/traits.h>
 
#if __cplusplus >= 202002L || (defined(_MSVC_LANG) && _MSVC_LANG >= 202002L)
 
template <typename T>
struct TINYOPT_FORMAT_NS::formatter<
    T, std::enable_if_t<std::is_base_of_v<tinyopt::DenseBase<T>, T>, char>> {
  template <typename ParseContext>
  constexpr auto parse(ParseContext& ctx) {
    return m_underlying.parse(ctx);
  }
  template <typename FormatContext>
  auto format(const T& m, FormatContext& ctx) const {
    std::ostringstream os;
    if (m.cols() == 1)  // print vectors as a row
      os << m.transpose();
    else
      os << m;
    auto out = ctx.out();
    out = TINYOPT_FORMAT_NS::format_to(ctx.out(), "{}", os.str());
    return out;
  }
 
 private:
  TINYOPT_FORMAT_NS::formatter<typename T::Scalar, char> m_underlying;
};
 
template <typename T>
struct TINYOPT_FORMAT_NS::formatter<
    T, std::enable_if_t<tinyopt::traits::is_sparse_matrix_v<T>, char>> {
  template <typename ParseContext>
  constexpr auto parse(ParseContext& ctx) {
    return m_underlying.parse(ctx);
  }
  template <typename FormatContext>
  auto format(const T& m, FormatContext& ctx) const {
    std::ostringstream os;
    os << m;
    auto out = ctx.out();
    out = TINYOPT_FORMAT_NS::format_to(ctx.out(), "{}", os.str());
    return out;
  }
 
 private:
  TINYOPT_FORMAT_NS::formatter<typename T::Scalar, char> m_underlying;
};
 
#endif
 
#if !(__cplusplus >= 202302L || (defined(_MSVC_LANG) && _MSVC_LANG >= 202302L))
 
// std::array
template <typename T, size_t N>
std::ostream& operator<<(std::ostream& os, const std::array<T, N>& v) {
  for (std::size_t i = 0; i < v.size(); ++i) {
    os << v[i];
    if (i + 1 < v.size()) os << " ";
  }
  return os;
}
 
// std::vector
template <typename T>
std::ostream& operator<<(std::ostream& os, const std::vector<T>& v) {
  for (std::size_t i = 0; i < v.size(); ++i) {
    os << v[i];
    if (i + 1 < v.size()) os << " ";
  }
  return os;
}
 
#endif  // c++23
 
#endif