From 773de5b8725e04db593fde75b18567f233108d65 Mon Sep 17 00:00:00 2001
From: Robin Moussu <robin.moussu@gmail.com>
Date: Fri, 25 Jan 2019 22:05:40 +0100
Subject: [PATCH] Add to string for std::optional

---
 .../internal/catch_compiler_capabilities.h    | 12 ++++++++++
 include/internal/catch_tostring.h             | 19 +++++++++++++++
 projects/CMakeLists.txt                       |  1 +
 .../UsageTests/ToStringOptional.tests.cpp     | 23 +++++++++++++++++++
 4 files changed, 55 insertions(+)
 create mode 100644 projects/SelfTest/UsageTests/ToStringOptional.tests.cpp

diff --git a/include/internal/catch_compiler_capabilities.h b/include/internal/catch_compiler_capabilities.h
index 968f662fce..012bf462a8 100644
--- a/include/internal/catch_compiler_capabilities.h
+++ b/include/internal/catch_compiler_capabilities.h
@@ -183,6 +183,14 @@
 #endif
 #endif
 
+////////////////////////////////////////////////////////////////////////////////
+// Check if optional is available and usable
+#if defined(__has_include)
+#  if __has_include(<optional>) && defined(CATCH_CPP17_OR_GREATER)
+#    define CATCH_INTERNAL_CONFIG_CPP17_OPTIONAL
+#  endif // __has_include(<optional>) && defined(CATCH_CPP17_OR_GREATER)
+#endif // __has_include
+
 ////////////////////////////////////////////////////////////////////////////////
 // Check if variant is available and usable
 #if defined(__has_include)
@@ -222,6 +230,10 @@
 #    define CATCH_CONFIG_CPP11_TO_STRING
 #endif
 
+#if defined(CATCH_INTERNAL_CONFIG_CPP17_OPTIONAL) && !defined(CATCH_CONFIG_NO_CPP17_OPTIONAL) && !defined(CATCH_CONFIG_CPP17_OPTIONAL)
+#  define CATCH_CONFIG_CPP17_OPTIONAL
+#endif
+
 #if defined(CATCH_INTERNAL_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS) && !defined(CATCH_CONFIG_NO_CPP17_UNCAUGHT_EXCEPTIONS) && !defined(CATCH_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS)
 #  define CATCH_CONFIG_CPP17_UNCAUGHT_EXCEPTIONS
 #endif
diff --git a/include/internal/catch_tostring.h b/include/internal/catch_tostring.h
index 3aff268bc3..13a43b0c8f 100644
--- a/include/internal/catch_tostring.h
+++ b/include/internal/catch_tostring.h
@@ -348,6 +348,7 @@ namespace Catch {
 #  define CATCH_CONFIG_ENABLE_TUPLE_STRINGMAKER
 #  define CATCH_CONFIG_ENABLE_VARIANT_STRINGMAKER
 #  define CATCH_CONFIG_ENABLE_CHRONO_STRINGMAKER
+#  define CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER
 #endif
 
 // Separate std::pair specialization
@@ -369,6 +370,24 @@ namespace Catch {
 }
 #endif // CATCH_CONFIG_ENABLE_PAIR_STRINGMAKER
 
+#if defined(CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER) && defined(CATCH_CONFIG_CPP17_OPTIONAL)
+#include <optional>
+namespace Catch {
+    template<typename T>
+    struct StringMaker<std::optional<T> > {
+        static std::string convert(const std::optional<T>& optional) {
+            ReusableStringStream rss;
+            if (optional.has_value()) {
+                rss << ::Catch::Detail::stringify(*optional);
+            } else {
+                rss << "{ }";
+            }
+            return rss.str();
+        }
+    };
+}
+#endif // CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER
+
 // Separate std::tuple specialization
 #if defined(CATCH_CONFIG_ENABLE_TUPLE_STRINGMAKER)
 #include <tuple>
diff --git a/projects/CMakeLists.txt b/projects/CMakeLists.txt
index 62fa7167fc..bc3914e0d4 100644
--- a/projects/CMakeLists.txt
+++ b/projects/CMakeLists.txt
@@ -36,6 +36,7 @@ set(TEST_SOURCES
         ${SELF_TEST_DIR}/UsageTests/Misc.tests.cpp
         ${SELF_TEST_DIR}/UsageTests/ToStringChrono.tests.cpp
         ${SELF_TEST_DIR}/UsageTests/ToStringGeneral.tests.cpp
+        ${SELF_TEST_DIR}/UsageTests/ToStringOptional.tests.cpp
         ${SELF_TEST_DIR}/UsageTests/ToStringPair.tests.cpp
         ${SELF_TEST_DIR}/UsageTests/ToStringTuple.tests.cpp
         ${SELF_TEST_DIR}/UsageTests/ToStringVariant.tests.cpp
diff --git a/projects/SelfTest/UsageTests/ToStringOptional.tests.cpp b/projects/SelfTest/UsageTests/ToStringOptional.tests.cpp
new file mode 100644
index 0000000000..d78579d905
--- /dev/null
+++ b/projects/SelfTest/UsageTests/ToStringOptional.tests.cpp
@@ -0,0 +1,23 @@
+#define CATCH_CONFIG_ENABLE_OPTIONAL_STRINGMAKER
+#include "catch.hpp"
+
+#if defined(CATCH_CONFIG_CPP17_OPTIONAL)
+
+TEST_CASE( "std::optional<int> -> toString", "[toString][optional][approvals]" ) {
+    using type = std::optional<int>;
+    REQUIRE( "{ }" == ::Catch::Detail::stringify( type{} ) );
+    REQUIRE( "0" == ::Catch::Detail::stringify( type{ 0 } ) );
+}
+
+TEST_CASE( "std::optional<std::string> -> toString", "[toString][optional][approvals]" ) {
+    using type = std::optional<std::string>;
+    REQUIRE( "{ }" == ::Catch::Detail::stringify( type{} ) );
+    REQUIRE( "\"abc\"" == ::Catch::Detail::stringify( type{ "abc" } ) );
+}
+
+TEST_CASE( "std::vector<std::optional<int> > -> toString", "[toString][optional][approvals]" ) {
+    using type = std::vector<std::optional<int> >;
+    REQUIRE( "{ 0, { }, 2 }" == ::Catch::Detail::stringify( type{ 0, {}, 2 } ) );
+}
+
+#endif // CATCH_INTERNAL_CONFIG_CPP17_OPTIONAL