Make it possible to use objects and collections with fmtlib

CMakeLists.txt

@@ -206,6 +206,8 @@ configure_file(${CMAKE_CURRENT_SOURCE_DIR}/python/__version__.py.in
 install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/LICENSE
         DESTINATION ${CMAKE_INSTALL_DOCDIR})
 
+find_package(fmt 9 REQUIRED)
+
 #--- project specific subdirectories -------------------------------------------
 add_subdirectory(src)
 
@@ -222,8 +224,6 @@ if(BUILD_TESTING)
   add_subdirectory(tests)
 endif()
 
-find_package(fmt 9 REQUIRED)
-
 add_subdirectory(tools)
 add_subdirectory(python)
 

cmake/podioConfig.cmake.in

@@ -30,6 +30,7 @@ if(NOT "@REQUIRE_PYTHON_VERSION@" STREQUAL "")
 else()
   find_dependency(Python3 COMPONENTS Interpreter Development)
 endif()
+find_dependency(fmt @fmt_VERSION@)
 
 SET(PODIO_ENABLE_SIO @ENABLE_SIO@)
 if(PODIO_ENABLE_SIO)

include/podio/ObjectID.h

@@ -1,6 +1,12 @@
 #ifndef PODIO_OBJECTID_H
 #define PODIO_OBJECTID_H
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+  #include <fmt/ostream.h>
+#endif
+
 #include <compare>
 #include <cstdint>
 #include <functional>
@@ -66,4 +72,9 @@ struct std::hash<podio::ObjectID> {
   }
 };
 
+#if !defined(__CLING__)
+template <>
+struct fmt::formatter<podio::ObjectID> : fmt::ostream_formatter {};
+#endif
+
 #endif

include/podio/UserDataCollection.h

@@ -8,6 +8,12 @@
 #include "podio/detail/Pythonizations.h"
 #include "podio/utilities/TypeHelpers.h"
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+  #include <fmt/ostream.h>
+#endif
+
 #define PODIO_ADD_USER_TYPE(type)                                                                                      \
   template <>                                                                                                          \
   consteval const char* userDataTypeName<type>() {                                                                     \
@@ -354,4 +360,9 @@ constexpr std::string_view UserDataCollection<BasicType, U>::dataTypeName;
 
 } // namespace podio
 
+#if !defined(__CLING__)
+template <typename BasicType>
+struct fmt::formatter<podio::UserDataCollection<BasicType>> : fmt::ostream_formatter {};
+#endif
+
 #endif

include/podio/detail/Link.h

@@ -12,6 +12,12 @@
   #include "nlohmann/json.hpp"
 #endif
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+  #include <fmt/ostream.h>
+#endif
+
 #include <functional>
 #include <ostream>
 #include <type_traits>
@@ -348,8 +354,8 @@ class LinkT {
   podio::utils::MaybeSharedPtr<LinkObjT> m_obj{nullptr};
 };
 
-template <typename FromT, typename ToT>
-std::ostream& operator<<(std::ostream& os, const Link<FromT, ToT>& link) {
+template <typename FromT, typename ToT, bool Mutable>
+std::ostream& operator<<(std::ostream& os, const LinkT<FromT, ToT, Mutable>& link) {
   if (!link.isAvailable()) {
     return os << "[not available]";
   }
@@ -382,4 +388,9 @@ struct std::hash<podio::LinkT<FromT, ToT, Mutable>> {
   }
 };
 
+#if !defined(__CLING__)
+template <typename FromT, typename ToT, bool Mutable>
+struct fmt::formatter<podio::LinkT<FromT, ToT, Mutable>> : fmt::ostream_formatter {};
+#endif
+
 #endif // PODIO_DETAIL_LINK_H

include/podio/detail/LinkCollectionImpl.h

@@ -28,6 +28,12 @@
   #include "nlohmann/json.hpp"
 #endif
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+  #include <fmt/ostream.h>
+#endif
+
 #include <iomanip>
 #include <memory>
 #include <mutex>
@@ -463,4 +469,9 @@ void to_json(nlohmann::json& j, const podio::LinkCollection<FromT, ToT>& collect
 
 } // namespace podio
 
+#if !defined(__CLING__)
+template <typename FromT, typename ToT>
+struct fmt::formatter<podio::LinkCollection<FromT, ToT>> : fmt::ostream_formatter {};
+#endif
+
 #endif // PODIO_DETAIL_LINKCOLLECTIONIMPL_H

python/templates/Collection.h.jinja2

@@ -30,6 +30,12 @@
 #include <memory>
 #include <cstddef>
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+#include <fmt/ostream.h>
+#endif
+
 namespace podio {
   struct RelationNames;
 }
@@ -280,6 +286,11 @@ void to_json(nlohmann::json& j, const {{ class.bare_type }}Collection& collectio
 
 {{ utils.namespace_close(class.namespace) }}
 
+#if !defined(__CLING__)
+template <>
+struct fmt::formatter<{% if class.namespace %}{{ class.namespace }}::{% endif %}{{ class.bare_type }}Collection> : fmt::ostream_formatter {};
+#endif
+
 {{ workarounds.ld_library_path(class, "Collection", ["valueTypeName", "dataTypeName"]) }}
 
 #endif

python/templates/Component.h.jinja2

@@ -11,6 +11,12 @@
 {% if generate_current_version %}
 #include <ostream>
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+#include <fmt/ostream.h>
+#endif
+
 #if defined(PODIO_JSON_OUTPUT) && !defined(__CLING__)
 #include "nlohmann/json_fwd.hpp"
 #endif
@@ -58,4 +64,11 @@ public:
 
 {{ utils.namespace_close(class.namespace) }}
 
+{% if generate_current_version %}
+#if !defined(__CLING__)
+template <>
+struct fmt::formatter<{{ class.full_type }}> : fmt::ostream_formatter {};
+#endif
+{% endif %}
+
 #endif

python/templates/Interface.h.jinja2

@@ -14,6 +14,12 @@
 #include "podio/utilities/TypeHelpers.h"
 #include "podio/detail/OrderKey.h"
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+#include <fmt/ostream.h>
+#endif
+
 #include <memory>
 #include <ostream>
 #include <stdexcept>
@@ -190,4 +196,9 @@ struct std::hash<{{ class.full_type }}> {
   }
 };
 
+#if !defined(__CLING__)
+template <>
+struct fmt::formatter<{{ class.full_type }}> : fmt::ostream_formatter {};
+#endif
+
 #endif

python/templates/MutableObject.h.jinja2

@@ -62,4 +62,7 @@ private:
 
 {{ macros.std_hash(class, prefix='Mutable') }}
 
+{{ macros.ostream_formatter(class, prefix='Mutable') }}
+
+
 #endif

python/templates/Object.h.jinja2

@@ -15,6 +15,12 @@
 #include "podio/utilities/MaybeSharedPtr.h"
 #include "podio/detail/OrderKey.h"
 
+// Hide the fmt dependency from cling, so that ROOT does not need to be able to
+// find the fmt headers when it parses the podio headers at runtime
+#if !defined(__CLING__)
+#include <fmt/ostream.h>
+#endif
+
 #include <ostream>
 #include <cstdint>
 
@@ -79,6 +85,8 @@ std::ostream& operator<<(std::ostream& o, const {{ class.bare_type }}& value);
 
 {{ macros.std_hash(class) }}
 
+{{ macros.ostream_formatter(class) }}
+
 {{ workarounds.ld_library_path(class) }}
 
 #endif

python/templates/macros/declarations.jinja2

@@ -153,3 +153,11 @@ struct std::hash<{{ namespace }}{{ prefix }}{{ class.bare_type }}> {
   }
 };
 {% endmacro %}
+
+{% macro ostream_formatter(class, prefix='') %}
+{% set namespace = class.namespace + '::' if class.namespace else '' %}
+#if !defined(__CLING__)
+template <>
+struct fmt::formatter<{{ namespace }}{{ prefix }}{{ class.bare_type }}> : fmt::ostream_formatter {};
+#endif
+{% endmacro %}

src/CMakeLists.txt

@@ -79,6 +79,7 @@ SET(core_headers
 PODIO_ADD_LIB_AND_DICT(podio "${core_headers}" "${core_sources}" selection.xml)
 target_compile_options(podio PRIVATE -pthread)
 target_link_libraries(podio PRIVATE Python3::Python)
+target_link_libraries(podio PUBLIC fmt::fmt)
 # For Frame.h
 if (ROOT_VERSION VERSION_LESS 6.36)
   target_compile_definitions(podio PUBLIC PODIO_ROOT_OLDER_6_36=1)

tests/unittests/interface_types.cpp

@@ -219,3 +219,14 @@ TEST_CASE("InterfaceType extension model", "[interface-types][extension]") {
   REQUIRE(wrapper.isA<iextension::AnotherHit>());
   REQUIRE(wrapper.as<iextension::AnotherHit>().energy() == 4.2f);
 }
+
+TEST_CASE("InterfaceType formatting", "[interface-types][basics][formatting]") {
+  auto iface = iextension::EnergyInterface::makeEmpty();
+  auto formatted = fmt::format("{}", iface);
+  REQUIRE(formatted == "[not available]");
+
+  iface = ExampleCluster{};
+  formatted = fmt::format("{}", iface);
+  REQUIRE_FALSE(formatted.empty());
+  REQUIRE(formatted != "[not available]");
+}

tests/unittests/links.cpp

@@ -15,6 +15,8 @@
   #include "nlohmann/json.hpp"
 #endif
 
+#include <fmt/format.h>
+
 #include <map>
 #include <set>
 #include <type_traits>
@@ -305,6 +307,22 @@ TEST_CASE("Links templated accessors", "[links]") {
   }
 }
 // NOLINTEND(clang-analyzer-cplusplus.NewDeleteLeaks)
+
+TEST_CASE("Link formatting", "[links]") {
+  TestL link;
+  auto formatted = fmt::format("{}", link);
+  REQUIRE_FALSE(formatted.empty());
+  REQUIRE(formatted != "[not available]");
+
+  auto emptyLink = TestL::makeEmpty();
+  auto emptyFmt = fmt::format("{}", emptyLink);
+  REQUIRE(emptyFmt == "[not available]");
+
+  TestMutL mutLink;
+  formatted = fmt::format("{}", mutLink);
+  REQUIRE(formatted != "[not avialable]");
+}
+
 TEST_CASE("LinkCollection collection concept", "[links][concepts]") {
   STATIC_REQUIRE(podio::CollectionType<TestLColl>);
   STATIC_REQUIRE(std::is_same_v<std::ranges::range_value_t<TestLColl>, TestL>);
@@ -449,6 +467,19 @@ TEST_CASE("LinkCollection basics", "[links]") {
   }
 }
 
+TEST_CASE("LinkCollection formatting", "[links][formatting]") {
+  podio::LinkCollection<ExampleHit, ExampleCluster> links;
+
+  auto formatted = fmt::format("{}", links);
+  REQUIRE_FALSE(formatted.empty());
+
+  links.create();
+  links.create();
+
+  auto formatted2 = fmt::format("{}", links);
+  REQUIRE(formatted2.size() > formatted.size());
+}
+
 auto createLinkCollections(const size_t nElements = 3u) {
   auto colls = std::make_tuple(TestLColl(), ExampleHitCollection(), ExampleClusterCollection());