Utility: support C++17 std::string_view in format().

doc/corrade-changelog.dox

@@ -203,6 +203,8 @@ namespace Corrade {
     sense from a portability point of view.
 -   @ref Utility::format() now supports printing integers as characters using
     the @cpp "{:c}" @ce modifier
+-   @ref Utility::format() now accepts also a C++17 @ref std::string_view if
+    you include @ref Corrade/Utility/FormatStlStringView.h
 -   @ref Utility::String::split() and
     @ref Utility::String::splitWithoutEmptyParts() now have
     @ref Containers::StringView overloads that allocate much less

src/Corrade/Utility/CMakeLists.txt

@@ -62,6 +62,7 @@ if(WITH_UTILITY)
         EndiannessBatch.h
         Format.h
         FormatStl.h
+        FormatStlStringView.h
         Macros.h
         Memory.h
         Move.h

src/Corrade/Utility/Format.h

@@ -88,6 +88,7 @@ In order to write a literal curly brace to the output, simply double it:
 | @ref Containers::StringView, \n @ref Containers::MutableStringView "MutableStringView", @ref Containers::String "String" | Written as a sequence of @ref Containers::StringView::size() characters
 | @ref Containers::ArrayView "Containers::ArrayView<const char>" @m_class{m-label m-danger} **deprecated** | Written as a sequence of @ref Containers::ArrayView::size() characters. \n Deprecated, use @ref Containers::StringView instead.
 | @ref std::string | Written as a sequence of @ref std::string::size() characters \n (@cpp #include @ce @ref Corrade/Utility/FormatStl.h in addition)
+| @ref std::string_view | Written as a sequence of @ref std::string_view::size() characters \n (@cpp #include @ce @ref Corrade/Utility/FormatStlStringView.h in addition)
 
 # Advanced formatting options
 

src/Corrade/Utility/FormatStl.h

@@ -31,7 +31,8 @@
 @m_since{2019,10}
 
 Including this header also allows you to use @ref std::string in arguments to
-@ref Utility::format().
+@ref Utility::format(). A separate @ref Corrade/Utility/FormatStlStringView.h
+header provides compatibility with @ref std::string_view from C++17.
 @experimental
 */
 

src/Corrade/Utility/FormatStlStringView.h

@@ -0,0 +1,60 @@
+#ifndef Corrade_Utility_FormatStlStringView_h
+#define Corrade_Utility_FormatStlStringView_h
+/*
+    This file is part of Corrade.
+
+    Copyright © 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
+                2017, 2018, 2019, 2020, 2021, 2022
+              Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+/** @file
+STL @ref std::string_view compatibility for @ref Utility::format()
+@m_since_latest
+
+Including this header allows you to use a C++17 @ref std::string_view in
+arguments to @ref Utility::format(). A separate @ref Corrade/Utility/FormatStl.h
+header provides compatibility with @ref std::string.
+@experimental
+*/
+
+#include <string_view>
+
+#include "Corrade/Containers/StringView.h"
+#include "Corrade/Utility/Format.h"
+
+/* Listing these namespaces doesn't add anything to the docs, so don't */
+#ifndef DOXYGEN_GENERATING_OUTPUT
+namespace Corrade { namespace Utility { namespace Implementation {
+
+template<> struct Formatter<std::string_view> {
+    static std::size_t format(const Containers::MutableStringView& buffer, std::string_view value, int precision, FormatType type) {
+        return Formatter<Containers::StringView>::format(buffer, {value.data(), value.size()}, precision, type);
+    }
+    static void format(std::FILE* file, std::string_view value, int precision, FormatType type) {
+        return Formatter<Containers::StringView>::format(file, {value.data(), value.size()}, precision, type);
+    }
+};
+
+}}}
+#endif
+
+#endif

src/Corrade/Utility/Test/CMakeLists.txt

@@ -171,10 +171,14 @@ if(NOT CMAKE_CXX_FLAGS MATCHES "-std=")
        (CMAKE_CXX_COMPILER_ID STREQUAL "Clang" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "5.0") OR
        (CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "9.3") OR
        (CMAKE_CXX_COMPILER_ID STREQUAL "MSVC" AND NOT CMAKE_CXX_COMPILER_VERSION VERSION_LESS "19.10"))
+        corrade_add_test(UtilityFormatStlStringViewTest FormatStlStringViewTest.cpp)
         corrade_add_test(UtilityMacrosCpp17Test MacrosCpp17Test.cpp)
-        set_target_properties(UtilityMacrosCpp17Test PROPERTIES
-            CORRADE_CXX_STANDARD 17
-            FOLDER "Corrade/Utility/Test")
+        set_target_properties(
+            UtilityFormatStlStringViewTest
+            UtilityMacrosCpp17Test
+            PROPERTIES
+                CORRADE_CXX_STANDARD 17
+                FOLDER "Corrade/Utility/Test")
     endif()
 
     # Copied verbatim from src/Corrade/Test/CMakeLists.txt, please keep in sync

src/Corrade/Utility/Test/FormatStlStringViewTest.cpp

@@ -0,0 +1,62 @@
+/*
+    This file is part of Corrade.
+
+    Copyright © 2007, 2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016,
+                2017, 2018, 2019, 2020, 2021, 2022
+              Vladimír Vondruš <mosra@centrum.cz>
+
+    Permission is hereby granted, free of charge, to any person obtaining a
+    copy of this software and associated documentation files (the "Software"),
+    to deal in the Software without restriction, including without limitation
+    the rights to use, copy, modify, merge, publish, distribute, sublicense,
+    and/or sell copies of the Software, and to permit persons to whom the
+    Software is furnished to do so, subject to the following conditions:
+
+    The above copyright notice and this permission notice shall be included
+    in all copies or substantial portions of the Software.
+
+    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+    THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+    FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+    DEALINGS IN THE SOFTWARE.
+*/
+
+#include "Corrade/Containers/String.h"
+#include "Corrade/TestSuite/Tester.h"
+#include "Corrade/Utility/FormatStlStringView.h"
+
+namespace Corrade { namespace Utility { namespace Test { namespace {
+
+struct FormatStlStringViewTest: TestSuite::Tester {
+    explicit FormatStlStringViewTest();
+
+    void test();
+    void testEmpty();
+};
+
+FormatStlStringViewTest::FormatStlStringViewTest() {
+    addTests({&FormatStlStringViewTest::test,
+              &FormatStlStringViewTest::testEmpty});
+}
+
+using namespace Containers::Literals;
+using namespace std::string_view_literals;
+
+void FormatStlStringViewTest::test() {
+    CORRADE_COMPARE(format("hello {}", std::string_view{"worlds", 5}),
+        "hello world");
+    CORRADE_COMPARE(format("hello {}", "world\0, i guess?"sv),
+        "hello world\0, i guess?"_s);
+}
+
+void FormatStlStringViewTest::testEmpty() {
+    /* Empty string view should not cause any issues with data access */
+    CORRADE_COMPARE(format("hello{}!", std::string_view{}), "hello!");
+}
+
+}}}}
+
+CORRADE_TEST_MAIN(Corrade::Utility::Test::FormatStlStringViewTest)