From dadf4ce2aba713522d1949a16ffbf0fa5d6e6298 Mon Sep 17 00:00:00 2001
From: Dario Izzo <darioizzo@gmail.com>
Date: Thu, 20 Oct 2022 11:52:59 +0200
Subject: [PATCH] stream formatters added to monomial types

---
 include/obake/detail/fmt_compat.hpp           | 64 +++++++++++++++++++
 .../obake/polynomials/d_packed_monomial.hpp   | 15 ++++-
 include/obake/polynomials/packed_monomial.hpp | 15 ++++-
 src/polynomials/packed_monomial.cpp           |  4 +-
 4 files changed, 89 insertions(+), 9 deletions(-)
 create mode 100644 include/obake/detail/fmt_compat.hpp

diff --git a/include/obake/detail/fmt_compat.hpp b/include/obake/detail/fmt_compat.hpp
new file mode 100644
index 00000000..d42779e3
--- /dev/null
+++ b/include/obake/detail/fmt_compat.hpp
@@ -0,0 +1,64 @@
+// Copyright 2020, 2021, 2022 Francesco Biscani (bluescarni@gmail.com), Dario Izzo (dario.izzo@gmail.com)
+//
+// This file is part of the heyoka library.
+//
+// This Source Code Form is subject to the terms of the Mozilla
+// Public License v. 2.0. If a copy of the MPL was not distributed
+// with this file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+#ifndef OBAKE_DETAIL_FMT_COMPAT_HPP
+#define OBAKE_DETAIL_FMT_COMPAT_HPP
+
+#include <stdexcept>
+
+#include <fmt/core.h>
+
+#if FMT_VERSION >= 90000L
+
+#include <fmt/ostream.h>
+
+#else
+
+#include <sstream>
+
+#include <fmt/format.h>
+
+#endif
+
+namespace obake::detail
+{
+
+#if FMT_VERSION >= 90000L
+
+using ostream_formatter = fmt::ostream_formatter;
+
+#else
+
+struct ostream_formatter {
+    template <typename ParseContext>
+    constexpr auto parse(ParseContext &ctx)
+    {
+        if (ctx.begin() != ctx.end()) {
+            // LCOV_EXCL_START
+            throw std::invalid_argument("The ostream formatter does not accept any format string");
+            // LCOV_EXCL_STOP
+        }
+
+        return ctx.begin();
+    }
+
+    template <typename T, typename FormatContext>
+    auto format(const T &x, FormatContext &ctx)
+    {
+        std::ostringstream oss;
+        oss << x;
+
+        return fmt::format_to(ctx.out(), "{}", oss.str());
+    }
+};
+
+#endif
+
+} // namespace obake::detail
+
+#endif
\ No newline at end of file
diff --git a/include/obake/polynomials/d_packed_monomial.hpp b/include/obake/polynomials/d_packed_monomial.hpp
index 5752e665..0b0f9621 100644
--- a/include/obake/polynomials/d_packed_monomial.hpp
+++ b/include/obake/polynomials/d_packed_monomial.hpp
@@ -27,9 +27,6 @@
 #include <boost/serialization/access.hpp>
 #include <boost/serialization/split_member.hpp>
 
-#include <fmt/format.h>
-#include <fmt/ostream.h>
-
 #include <tbb/blocked_range.h>
 #include <tbb/parallel_invoke.h>
 #include <tbb/parallel_reduce.h>
@@ -37,6 +34,7 @@
 #include <mp++/integer.hpp>
 
 #include <obake/config.hpp>
+#include <obake/detail/fmt_compat.hpp>
 #include <obake/detail/ignore.hpp>
 #include <obake/detail/limits.hpp>
 #include <obake/detail/mppp_utils.hpp>
@@ -1424,6 +1422,17 @@ inline constexpr bool monomial_hash_is_homomorphic<d_packed_monomial<T, PSize>>
 
 } // namespace obake
 
+// fmt formatter for d_packed_monomial, implemented
+// on top of the streaming operator.
+namespace fmt
+{
+
+template <typename T>
+struct formatter<obake::d_packed_monomial<T>> : obake::detail::ostream_formatter {
+};
+
+} // namespace fmt
+
 namespace boost::serialization
 {
 
diff --git a/include/obake/polynomials/packed_monomial.hpp b/include/obake/polynomials/packed_monomial.hpp
index a40c0475..671c2545 100644
--- a/include/obake/polynomials/packed_monomial.hpp
+++ b/include/obake/polynomials/packed_monomial.hpp
@@ -24,9 +24,6 @@
 
 #include <boost/serialization/access.hpp>
 
-#include <fmt/format.h>
-#include <fmt/ostream.h>
-
 #include <tbb/blocked_range.h>
 #include <tbb/parallel_invoke.h>
 #include <tbb/parallel_reduce.h>
@@ -34,6 +31,7 @@
 #include <mp++/integer.hpp>
 
 #include <obake/config.hpp>
+#include <obake/detail/fmt_compat.hpp>
 #include <obake/detail/ignore.hpp>
 #include <obake/detail/mppp_utils.hpp>
 #include <obake/detail/to_string.hpp>
@@ -799,6 +797,17 @@ inline constexpr bool monomial_hash_is_homomorphic<packed_monomial<T>> = true;
 
 } // namespace obake
 
+// fmt formatter for packed_monomial, implemented
+// on top of the streaming operator.
+namespace fmt
+{
+
+template <typename T>
+struct formatter<obake::packed_monomial<T>> : obake::detail::ostream_formatter {
+};
+
+} // namespace fmt
+
 namespace boost::serialization
 {
 
diff --git a/src/polynomials/packed_monomial.cpp b/src/polynomials/packed_monomial.cpp
index f0927831..df81789f 100644
--- a/src/polynomials/packed_monomial.cpp
+++ b/src/polynomials/packed_monomial.cpp
@@ -14,12 +14,10 @@
 #include <utility>
 #include <vector>
 
-#include <fmt/format.h>
-#include <fmt/ostream.h>
-
 #include <mp++/integer.hpp>
 
 #include <obake/config.hpp>
+#include <obake/detail/fmt_compat.hpp>
 #include <obake/detail/ignore.hpp>
 #include <obake/detail/limits.hpp>
 #include <obake/exceptions.hpp>