Rework internals of CATCH_REGISTER_ENUM

The old internals reached into the global hub to stash the allocation(s)
for enum value -> string value there, then kept around a potentially
invalid (in case the hub was cleaned up) reference into it, going through
whole bunch of virtual dispatch in the process.

The new internals just store the data in a static variable inside the
`StringMaker` specialization. This avoids potential lifetime issues,
avoids all virtual dispatch and (almost) reduces the include bloat in
the main header path.

The reason for (almost) there is that for full include correctness,
`EnumInfo` needs `<utility>` include for `std::pair`. However, this brings
in things like `std::relops`, because the std headers in C++ are dumb.
As this was not included before, and instead we relied on `std::pair`
existing in an internal stdlib header that we transitively included, the
full include size ends up bigger than before.

1 files changed, 65 insertions, 0 deletions

diff --git a/src/catch2/internal/catch_enum_info.cpp b/src/catch2/internal/catch_enum_info.cpp
new file mode 100644
index 00000000..0793abd9
--- /dev/null
+++ b/src/catch2/internal/catch_enum_info.cpp
@@ -0,0 +1,65 @@
+
+//              Copyright Catch2 Authors
+// Distributed under the Boost Software License, Version 1.0.
+//   (See accompanying file LICENSE.txt or copy at
+//        https://www.boost.org/LICENSE_1_0.txt)
+
+// SPDX-License-Identifier: BSL-1.0
+
+#include <catch2/internal/catch_enum_info.hpp>
+#include <catch2/internal/catch_string_manip.hpp>
+
+#include <cassert>
+
+namespace Catch {
+
+    namespace Detail {
+
+        namespace {
+            // Extracts the actual name part of an enum instance
+            // In other words, it returns the Blue part of Bikeshed::Colour::Blue
+            StringRef extractInstanceName(StringRef enumInstance) {
+                // Find last occurrence of ":"
+                size_t name_start = enumInstance.size();
+                while (name_start > 0 && enumInstance[name_start - 1] != ':') {
+                    --name_start;
+                }
+                return enumInstance.substr(name_start, enumInstance.size() - name_start);
+            }
+        }
+
+        std::vector<StringRef> parseEnums( StringRef enums ) {
+            auto enumValues = splitStringRef( enums, ',' );
+            std::vector<StringRef> parsed;
+            parsed.reserve( enumValues.size() );
+            for( auto const& enumValue : enumValues ) {
+                parsed.push_back(trim(extractInstanceName(enumValue)));
+            }
+            return parsed;
+        }
+
+        StringRef EnumInfo::lookup( int64_t value ) const {
+            for( auto const& valueToName : m_values ) {
+                if( valueToName.first == value )
+                    return valueToName.second;
+            }
+            return "{** unexpected enum value **}"_sr;
+        }
+
+        EnumInfo makeEnumInfo( StringRef enumName, StringRef allValueNames, std::vector<int64_t> const& values ) {
+            EnumInfo enumInfo;
+            enumInfo.m_name = enumName;
+            enumInfo.m_values.reserve( values.size() );
+
+            const auto valueNames = Catch::Detail::parseEnums( allValueNames );
+            assert( valueNames.size() == values.size() );
+            for (size_t i = 0; i < values.size(); ++i) {
+                enumInfo.m_values.emplace_back( values[i], valueNames[i] );
+            }
+
+            return enumInfo;
+        }
+
+    } // Detail
+} // Catch
+