Release 2.3.0, use std::optional if available

README.md

@@ -1,6 +1,6 @@
 optional lite - A single-file header-only version of a C++17-like optional, a nullable object for C++98, C++11 and later
 ====================================================
-[![Language](https://img.shields.io/badge/language-C++-blue.svg)](https://isocpp.org/)  [![Standard](https://img.shields.io/badge/c%2B%2B-98/11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://opensource.org/licenses/MIT) [![Build Status](https://travis-ci.org/martinmoene/optional-lite.svg?branch=master)](https://travis-ci.org/martinmoene/optional-lite) [![Build status](https://ci.appveyor.com/api/projects/status/1oq5gjm7bufrv6ib?svg=true)](https://ci.appveyor.com/project/martinmoene/optional-lite) [![Version](https://badge.fury.io/gh/martinmoene%2Foptional-lite.svg)](https://github.com/martinmoene/optional-lite/releases) [![download](https://img.shields.io/badge/latest-download-blue.svg)](https://raw.githubusercontent.com/martinmoene/optional-lite/master/include/nonstd/optional.hpp) [![Conan](https://img.shields.io/badge/conan-download-blue.svg)](https://bintray.com/agauniyal/nonstd-lite/optional-lite%3Anonstd-lite/_latestVersion) [![Try it online](https://img.shields.io/badge/try%20it-online-blue.svg)](https://wandbox.org/permlink/4gJ5Yhyv0bwzJ5x8)
+[![Language](https://img.shields.io/badge/language-C++-blue.svg)](https://isocpp.org/)  [![Standard](https://img.shields.io/badge/c%2B%2B-98/11-blue.svg)](https://en.wikipedia.org/wiki/C%2B%2B#Standardization) [![License](https://img.shields.io/badge/license-MIT-blue.svg)](https://opensource.org/licenses/MIT) [![Build Status](https://travis-ci.org/martinmoene/optional-lite.svg?branch=master)](https://travis-ci.org/martinmoene/optional-lite) [![Build status](https://ci.appveyor.com/api/projects/status/1oq5gjm7bufrv6ib?svg=true)](https://ci.appveyor.com/project/martinmoene/optional-lite) [![Version](https://badge.fury.io/gh/martinmoene%2Foptional-lite.svg)](https://github.com/martinmoene/optional-lite/releases) [![download](https://img.shields.io/badge/latest-download-blue.svg)](https://raw.githubusercontent.com/martinmoene/optional-lite/master/include/nonstd/optional.hpp) [![Conan](https://img.shields.io/badge/conan-download-blue.svg)](https://bintray.com/agauniyal/nonstd-lite/optional-lite%3Anonstd-lite/_latestVersion) [![Try it online](https://img.shields.io/badge/try%20it-online-blue.svg)](https://wandbox.org/permlink/DMZg1wOekSwEb54i)
 
 **Contents**  
 - [Example usage](#example-usage)
@@ -56,7 +56,7 @@ prompt>g++ -Wall -Wextra -std=c++03 -I.. -o to_int.exe to_int.cpp && to_int x1
 
 In a nutshell
 ---------------
-**optional lite** is a single-file header-only library to represent optional (nullable) objects and pass them by value. The library aims to provide a [C++17-like optional](http://en.cppreference.com/w/cpp/utility/optional) for use with C++98 and later. There's also a simpler version, [*optional bare*](https://github.com/martinmoene/optional-bare). Unlike *optional lite*, *optional bare* is limited to default-constructible and copyable types. 
+**optional lite** is a single-file header-only library to represent optional (nullable) objects and pass them by value. The library aims to provide a [C++17-like optional](http://en.cppreference.com/w/cpp/utility/optional) for use with C++98 and later. If available, std::optional is used. There's also a simpler version, [*optional bare*](https://github.com/martinmoene/optional-bare). Unlike *optional lite*, *optional bare* is limited to default-constructible and copyable types. 
 
 **Features and properties of optional lite** are ease of installation (single header), freedom of dependencies other than the standard library and control over object alignment (if needed). *optional lite* shares the approach to in-place tags with [any-lite](https://github.com/martinmoene/any-lite) and with [variant-lite](https://github.com/martinmoene/variant-lite) and these libraries can be used together.
 

include/nonstd/optional.hpp

@@ -1,5 +1,5 @@
 //
-// Copyright (c) 2016 Martin Moene
+// Copyright (c) 2014-2017 Martin Moene
 //
 // https://github.com/martinmoene/optional-lite
 //
@@ -18,12 +18,58 @@
 #ifndef NONSTD_OPTIONAL_LITE_HPP
 #define NONSTD_OPTIONAL_LITE_HPP
 
+#define  optional_lite_VERSION "2.3.0"
+
+// Compiler detection:
+
+#define optional_CPP11_OR_GREATER  ( __cplusplus >= 201103L )
+#define optional_CPP14_OR_GREATER  ( __cplusplus >= 201402L )
+#define optional_CPP17_OR_GREATER  ( __cplusplus >= 201703L )
+
+// use C++17 std::optional if available:
+
+#if defined( __has_include )
+# define optional_HAS_INCLUDE( arg )  __has_include( arg )
+#else
+# define optional_HAS_INCLUDE( arg )  0
+#endif
+
+#if optional_HAS_INCLUDE( <optional> ) && optional_CPP17_OR_GREATER
+
+#define optional_HAVE_STD_OPTIONAL  1
+
+#include <optional>
+
+namespace nonstd {
+
+    using std::optional;
+    using std::bad_optional_access;
+    using std::hash;
+
+    using std::nullopt;
+    using std::in_place;
+    using std::in_place_type;
+    using std::in_place_index;
+    using std::in_place_t;
+    using std::in_place_type_t;
+    using std::in_place_index_t;
+
+    using std::operator==;
+    using std::operator!=;
+    using std::operator<;
+    using std::operator<=;
+    using std::operator>;
+    using std::operator>=;
+    using std::make_optional;
+    using std::swap;
+}
+
+#else // C++17 std::optional
+
 #include <cassert>
 #include <stdexcept>
 #include <utility>
 
-#define  optional_lite_VERSION "2.2.1"
-
 // optional-lite alignment configuration:
 
 #ifndef  optional_CONFIG_MAX_ALIGN_HACK
@@ -38,12 +84,6 @@
 # define optional_CONFIG_ALIGN_AS_FALLBACK  double
 #endif
 
-// Compiler detection (C++17 is speculative):
-
-#define optional_CPP11_OR_GREATER  ( __cplusplus >= 201103L )
-#define optional_CPP14_OR_GREATER  ( __cplusplus >= 201402L )
-#define optional_CPP17_OR_GREATER  ( __cplusplus >= 201700L )
-
 // half-open range [lo..hi):
 #define optional_BETWEEN( v, lo, hi ) ( lo <= v && v < hi )
 
@@ -226,6 +266,18 @@ inline in_place_t in_place( detail::in_place_index_tag<I> = detail::in_place_ind
     return in_place_t();
 }
 
+template< class T >
+inline in_place_t in_place_type( detail::in_place_type_tag<T> = detail::in_place_type_tag<T>() )
+{
+    return in_place_t();
+}
+
+template< std::size_t I >
+inline in_place_t in_place_index( detail::in_place_index_tag<I> = detail::in_place_index_tag<I>() )
+{
+    return in_place_t();
+}
+
 // mimic templated typedef:
 
 #define nonstd_lite_in_place_type_t( T)  nonstd::in_place_t(&)( nonstd::detail::in_place_type_tag<T>  )
@@ -1114,4 +1166,6 @@ struct hash< nonstd::optional<T> >
 
 #endif // optional_CPP11_OR_GREATER
 
+#endif // have C++17 std::optional
+
 #endif // NONSTD_OPTIONAL_LITE_HPP

test/optional.t.cpp

@@ -1,5 +1,5 @@
 //
-// Copyright 2014-2016 by Martin Moene
+// Copyright 2014-2017 by Martin Moene
 //
 // Distributed under the Boost Software License, Version 1.0. (See accompanying
 // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
@@ -249,7 +249,11 @@ CASE( "optional: Allows to in-place copy-construct from value (C++11)" )
 
     EXPECT( a->first        == 'a' );
     EXPECT( a->second.value ==  7  );
+#if optional_HAVE_STD_OPTIONAL
+    EXPECT( a->second.state == copy_constructed );
+#else
     EXPECT( a->second.state == move_constructed );
+#endif
     EXPECT(         s.state != moved_from       );
 #else
     EXPECT( !!"optional: in-place construction is not available (no C++11)" );
@@ -284,7 +288,11 @@ CASE( "optional: Allows to in-place copy-construct from initializer-list (C++11)
     EXPECT( a->vec[2]  ==  9 );
     EXPECT( a->c       == 'a');
     EXPECT( a->s.value ==  7 );
+#if optional_HAVE_STD_OPTIONAL
+    EXPECT( a->s.state == copy_constructed );
+#else
     EXPECT( a->s.state == move_constructed );
+#endif
     EXPECT(    s.state != moved_from       );
 #else
     EXPECT( !!"optional: in-place construction is not available (no C++11)" );
@@ -402,7 +410,11 @@ CASE( "optional: Allows to copy-emplace content from arguments (C++11)" )
 
     EXPECT( a->first        == 'a' );
     EXPECT( a->second.value ==  7  );
+#if optional_HAVE_STD_OPTIONAL
+    EXPECT( a->second.state == copy_constructed );
+#else
     EXPECT( a->second.state == move_constructed );
+#endif
     EXPECT(         s.state != moved_from       );
 #else
     EXPECT( !!"optional: in-place construction is not available (no C++11)" );
@@ -440,7 +452,11 @@ CASE( "optional: Allows to copy-emplace content from intializer-list and argumen
     EXPECT( a->vec[2]  ==  9  );
     EXPECT( a->c       == 'a' );
     EXPECT( a->s.value ==  7  );
+#if optional_HAVE_STD_OPTIONAL
+    EXPECT( a->s.state == copy_constructed );
+#else
     EXPECT( a->s.state == move_constructed );
+#endif
     EXPECT(    s.state != moved_from       );
 #else
     EXPECT( !!"optional: in-place construction is not available (no C++11)" );
@@ -734,7 +750,11 @@ CASE( "make_optional: Allows to in-place copy-construct optional from arguments
 
     EXPECT( a->first        == 'a' );
     EXPECT( a->second.value ==  7  );
+#if optional_HAVE_STD_OPTIONAL
+    EXPECT( a->second.state == copy_constructed );
+#else
     EXPECT( a->second.state == move_constructed );
+#endif
     EXPECT(         s.state != moved_from       );
 #else
     EXPECT( !!"optional: in-place construction is not available (no C++11)" );
@@ -769,7 +789,11 @@ CASE( "make_optional: Allows to in-place copy-construct optional from initialize
     EXPECT( a->vec[2]  ==  9  );
     EXPECT( a->c       == 'a' );
     EXPECT( a->s.value ==  7  );
+#if optional_HAVE_STD_OPTIONAL
+    EXPECT( a->s.state == copy_constructed );
+#else
     EXPECT( a->s.state == move_constructed );
+#endif
     EXPECT(    s.state != moved_from       );
 #else
     EXPECT( !!"optional: in-place construction is not available (no C++11)" );
@@ -841,8 +865,10 @@ CASE("storage_t: Show sizeof various optionals"
      "[.]" )
 {
     std::cout <<
+#ifndef optional_HAVE_STD_OPTIONAL
         "sizeof( nonstd::optional_lite::detail::storage_t<char> ): " <<
          sizeof( nonstd::optional_lite::detail::storage_t<char> )    << "\n" <<
+#endif
          optional_OUTPUT_SIZEOF( char )
          optional_OUTPUT_SIZEOF( short )
          optional_OUTPUT_SIZEOF( int )