Use std::string_view for C++17 or later, and std::experimental::strin…

…g_view for C++14.

Define the preprocessor macro BOOST_ASIO_DISABLE_STD_STRING_VIEW to
force the use of std::experimental::string_view (assuming it is
available) when compiling in C++17 mode.

include/boost/asio/buffer.hpp

@@ -1476,7 +1476,7 @@ inline BOOST_ASIO_CONST_BUFFER buffer(
       );
 }
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+#if defined(BOOST_ASIO_HAS_STRING_VIEW) \
   || defined(GENERATING_DOCUMENTATION)
 
 /// Create a new modifiable buffer that represents the given string_view.
@@ -1521,7 +1521,7 @@ inline BOOST_ASIO_CONST_BUFFER buffer(
       );
 }
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
        //  || defined(GENERATING_DOCUMENTATION)
 
 /*@}*/

include/boost/asio/detail/config.hpp

@@ -771,32 +771,61 @@
 # endif // !defined(BOOST_ASIO_DISABLE_STD_FUTURE)
 #endif // !defined(BOOST_ASIO_HAS_STD_FUTURE)
 
-// Standard library support for experimental::string_view.
+// Standard library support for std::string_view.
 #if !defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
 # if !defined(BOOST_ASIO_DISABLE_STD_STRING_VIEW)
 #  if defined(__clang__)
+#   if (__cplusplus >= 201703)
+#    if __has_include(<string_view>)
+#     define BOOST_ASIO_HAS_STD_STRING_VIEW 1
+#    endif // __has_include(<string_view>)
+#   endif // (__cplusplus >= 201703)
+#  endif // defined(__clang__)
+#  if defined(__GNUC__)
+#   if (__GNUC__ >= 7)
+#    if (__cplusplus >= 201703)
+#     define BOOST_ASIO_HAS_STD_STRING_VIEW 1
+#    endif // (__cplusplus >= 201703)
+#   endif // (__GNUC__ >= 7)
+#  endif // defined(__GNUC__)
+#  if defined(BOOST_ASIO_MSVC)
+#   if (_MSC_VER >= 1910 && _HAS_CXX17)
+#    define BOOST_ASIO_HAS_STD_STRING_VIEW
+#   endif // (_MSC_VER >= 1910 && _HAS_CXX17)
+#  endif // defined(BOOST_ASIO_MSVC)
+# endif // !defined(BOOST_ASIO_DISABLE_STD_STRING_VIEW)
+#endif // !defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+
+// Standard library support for std::experimental::string_view.
+#if !defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+# if !defined(BOOST_ASIO_DISABLE_STD_EXPERIMENTAL_STRING_VIEW)
+#  if defined(__clang__)
 #   if (__cplusplus >= 201402)
 #    if __has_include(<experimental/string_view>)
-#     define BOOST_ASIO_HAS_STD_STRING_VIEW 1
 #     define BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW 1
 #    endif // __has_include(<experimental/string_view>)
 #   endif // (__cplusplus >= 201402)
 #  endif // defined(__clang__)
 #  if defined(__GNUC__)
 #   if ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 9)) || (__GNUC__ > 4)
 #    if (__cplusplus >= 201402)
-#     define BOOST_ASIO_HAS_STD_STRING_VIEW 1
 #     define BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW 1
 #    endif // (__cplusplus >= 201402)
-#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 7)) || (__GNUC__ > 4)
+#   endif // ((__GNUC__ == 4) && (__GNUC_MINOR__ >= 9)) || (__GNUC__ > 4)
 #  endif // defined(__GNUC__)
-#  if defined(BOOST_ASIO_MSVC)
-#   if (_MSC_VER >= 1910 && _HAS_CXX17)
-#    define BOOST_ASIO_HAS_STD_STRING_VIEW
-#   endif // (_MSC_VER >= 1910)
-#  endif // defined(BOOST_ASIO_MSVC)
-# endif // !defined(BOOST_ASIO_DISABLE_STD_STRING_VIEW)
-#endif // !defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+# endif // !defined(BOOST_ASIO_DISABLE_STD_EXPERIMENTAL_STRING_VIEW)
+#endif // !defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+
+// Standard library has a string_view that we can use.
+#if !defined(BOOST_ASIO_HAS_STRING_VIEW)
+# if !defined(BOOST_ASIO_DISABLE_STRING_VIEW)
+#  if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#   define BOOST_ASIO_HAS_STRING_VIEW 1
+#  elif defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+#   define BOOST_ASIO_HAS_STRING_VIEW 1
+#  endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+# endif // !defined(BOOST_ASIO_DISABLE_STRING_VIEW)
+#endif // !defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 // Standard library support for iostream move construction and assignment.
 #if !defined(BOOST_ASIO_HAS_STD_IOSTREAM_MOVE)

include/boost/asio/detail/string_view.hpp

@@ -17,31 +17,33 @@
 
 #include <boost/asio/detail/config.hpp>
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
 
-#if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
-# include <experimental/string_view>
-#else // defined(BOOST_ASIO_HAS_EXPERIMENTAL_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
 # include <string_view>
-#endif // defined(BOOST_ASIO_HAS_EXPERIMENTAL_STRING_VIEW)
+#elif defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+# include <experimental/string_view>
+#else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+# error BOOST_ASIO_HAS_STRING_VIEW is set but no string_view is available
+#endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
 
 namespace boost {
 namespace asio {
 
-#if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
-using std::experimental::basic_string_view;
-using std::experimental::string_view;
-#else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
 using std::basic_string_view;
 using std::string_view;
+#elif defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+using std::experimental::basic_string_view;
+using std::experimental::string_view;
 #endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
 
 } // namespace asio
 } // namespace boost
 
 # define BOOST_ASIO_STRING_VIEW_PARAM boost::asio::string_view
-#else // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#else // defined(BOOST_ASIO_HAS_STRING_VIEW)
 # define BOOST_ASIO_STRING_VIEW_PARAM const std::string&
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 #endif // BOOST_ASIO_DETAIL_STRING_VIEW_HPP

include/boost/asio/ip/address.hpp

@@ -207,7 +207,7 @@ BOOST_ASIO_DECL address make_address(const std::string& str);
 BOOST_ASIO_DECL address make_address(
     const std::string& str, boost::system::error_code& ec);
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+#if defined(BOOST_ASIO_HAS_STRING_VIEW) \
   || defined(GENERATING_DOCUMENTATION)
 
 /// Create an address from an IPv4 address string in dotted decimal form,
@@ -225,7 +225,7 @@ BOOST_ASIO_DECL address make_address(string_view str);
 BOOST_ASIO_DECL address make_address(
     string_view str, boost::system::error_code& ec);
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
        //  || defined(GENERATING_DOCUMENTATION)
 
 #if !defined(BOOST_ASIO_NO_IOSTREAM)

include/boost/asio/ip/address_v4.hpp

@@ -278,7 +278,7 @@ BOOST_ASIO_DECL address_v4 make_address_v4(const std::string& str);
 BOOST_ASIO_DECL address_v4 make_address_v4(
     const std::string& str, boost::system::error_code& ec);
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+#if defined(BOOST_ASIO_HAS_STRING_VIEW) \
   || defined(GENERATING_DOCUMENTATION)
 
 /// Create an IPv4 address from an IP address string in dotted decimal form.
@@ -294,7 +294,7 @@ BOOST_ASIO_DECL address_v4 make_address_v4(string_view str);
 BOOST_ASIO_DECL address_v4 make_address_v4(
     string_view str, boost::system::error_code& ec);
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
        //  || defined(GENERATING_DOCUMENTATION)
 
 #if !defined(BOOST_ASIO_NO_IOSTREAM)

include/boost/asio/ip/address_v6.hpp

@@ -267,7 +267,7 @@ BOOST_ASIO_DECL address_v6 make_address_v6(const std::string& str);
 BOOST_ASIO_DECL address_v6 make_address_v6(
     const std::string& str, boost::system::error_code& ec);
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+#if defined(BOOST_ASIO_HAS_STRING_VIEW) \
   || defined(GENERATING_DOCUMENTATION)
 
 /// Create an IPv6 address from an IP address string.
@@ -283,7 +283,7 @@ BOOST_ASIO_DECL address_v6 make_address_v6(string_view str);
 BOOST_ASIO_DECL address_v6 make_address_v6(
     string_view str, boost::system::error_code& ec);
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
        //  || defined(GENERATING_DOCUMENTATION)
 
 /// Tag type used for distinguishing overloads that deal in IPv4-mapped IPv6

include/boost/asio/ip/impl/address.ipp

@@ -135,7 +135,7 @@ address make_address(const std::string& str,
   return make_address(str.c_str(), ec);
 }
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 address make_address(string_view str)
 {
@@ -148,7 +148,7 @@ address make_address(string_view str,
   return make_address(static_cast<std::string>(str), ec);
 }
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 boost::asio::ip::address_v4 address::to_v4() const
 {

include/boost/asio/ip/impl/address_v4.ipp

@@ -188,7 +188,7 @@ address_v4 make_address_v4(
   return make_address_v4(str.c_str(), ec);
 }
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 address_v4 make_address_v4(string_view str)
 {
@@ -201,7 +201,7 @@ address_v4 make_address_v4(string_view str,
   return make_address_v4(static_cast<std::string>(str), ec);
 }
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 } // namespace ip
 } // namespace asio

include/boost/asio/ip/impl/address_v6.ipp

@@ -304,7 +304,7 @@ address_v6 make_address_v6(
   return make_address_v6(str.c_str(), ec);
 }
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 address_v6 make_address_v6(string_view str)
 {
@@ -317,7 +317,7 @@ address_v6 make_address_v6(string_view str,
   return make_address_v6(static_cast<std::string>(str), ec);
 }
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 address_v4 make_address_v4(
     v4_mapped_t, const address_v6& v6_addr)

include/boost/asio/ip/impl/network_v4.ipp

@@ -193,7 +193,7 @@ network_v4 make_network_v4(const std::string& str,
   return network_v4(addr, static_cast<unsigned short>(prefix_len));
 }
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 network_v4 make_network_v4(string_view str)
 {
@@ -206,7 +206,7 @@ network_v4 make_network_v4(string_view str,
   return make_network_v4(static_cast<std::string>(str), ec);
 }
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 } // namespace ip
 } // namespace asio

include/boost/asio/ip/impl/network_v6.ipp

@@ -162,7 +162,7 @@ network_v6 make_network_v6(const std::string& str,
   return network_v6(addr, static_cast<unsigned short>(prefix_len));
 }
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 network_v6 make_network_v6(string_view str)
 {
@@ -175,7 +175,7 @@ network_v6 make_network_v6(string_view str,
   return make_network_v6(static_cast<std::string>(str), ec);
 }
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
 } // namespace ip
 } // namespace asio

include/boost/asio/ip/network_v4.hpp

@@ -208,7 +208,7 @@ BOOST_ASIO_DECL network_v4 make_network_v4(const std::string& str);
 BOOST_ASIO_DECL network_v4 make_network_v4(
     const std::string& str, boost::system::error_code& ec);
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+#if defined(BOOST_ASIO_HAS_STRING_VIEW) \
   || defined(GENERATING_DOCUMENTATION)
 
 /// Create an IPv4 network from a string containing IP address and prefix
@@ -226,7 +226,7 @@ BOOST_ASIO_DECL network_v4 make_network_v4(string_view str);
 BOOST_ASIO_DECL network_v4 make_network_v4(
     string_view str, boost::system::error_code& ec);
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
        //  || defined(GENERATING_DOCUMENTATION)
 
 #if !defined(BOOST_ASIO_NO_IOSTREAM)

include/boost/asio/ip/network_v6.hpp

@@ -182,7 +182,7 @@ BOOST_ASIO_DECL network_v6 make_network_v6(const std::string& str);
 BOOST_ASIO_DECL network_v6 make_network_v6(
     const std::string& str, boost::system::error_code& ec);
 
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW) \
+#if defined(BOOST_ASIO_HAS_STRING_VIEW) \
   || defined(GENERATING_DOCUMENTATION)
 
 /// Create an IPv6 network from a string containing IP address and prefix
@@ -200,7 +200,7 @@ BOOST_ASIO_DECL network_v6 make_network_v6(string_view str);
 BOOST_ASIO_DECL network_v6 make_network_v6(
     string_view str, boost::system::error_code& ec);
 
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
        //  || defined(GENERATING_DOCUMENTATION)
 
 #if !defined(BOOST_ASIO_NO_IOSTREAM)

test/buffer.cpp

@@ -62,12 +62,10 @@ void test()
     std::vector<mutable_buffer> mutable_buffer_sequence;
     std::vector<const_buffer> const_buffer_sequence;
 #if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
-# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
-    std::experimental::string_view string_view_data(string_data);
-# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
     std::string_view string_view_data(string_data);
-# endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#elif defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_data(string_data);
+#endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
 
     // mutable_buffer constructors.
 
@@ -204,10 +202,10 @@ void test()
     mb1 = buffer(string_data, 1024);
     cb1 = buffer(const_string_data);
     cb1 = buffer(const_string_data, 1024);
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
     cb1 = buffer(string_view_data);
     cb1 = buffer(string_view_data, 1024);
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
     // buffer_copy function overloads.
 

test/ip/address.cpp

@@ -108,15 +108,15 @@ void test()
     addr1 = ip::make_address("127.0.0.1", ec);
     addr1 = ip::make_address(string_value);
     addr1 = ip::make_address(string_value, ec);
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
-# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
-    std::experimental::string_view string_view_value("127.0.0.1");
-# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
     std::string_view string_view_value("127.0.0.1");
+# elif defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_value("127.0.0.1");
 # endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
     addr1 = ip::make_address(string_view_value);
     addr1 = ip::make_address(string_view_value, ec);
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
     // address I/O.
 

test/ip/address_v4.cpp

@@ -132,15 +132,15 @@ void test()
     addr1 = ip::make_address_v4("127.0.0.1", ec);
     addr1 = ip::make_address_v4(string_value);
     addr1 = ip::make_address_v4(string_value, ec);
-#if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
-# if defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
-    std::experimental::string_view string_view_value("127.0.0.1");
-# else // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+#if defined(BOOST_ASIO_HAS_STRING_VIEW)
+# if defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
     std::string_view string_view_value("127.0.0.1");
+# elif defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
+    std::experimental::string_view string_view_value("127.0.0.1");
 # endif // defined(BOOST_ASIO_HAS_STD_EXPERIMENTAL_STRING_VIEW)
     addr1 = ip::make_address_v4(string_view_value);
     addr1 = ip::make_address_v4(string_view_value, ec);
-#endif // defined(BOOST_ASIO_HAS_STD_STRING_VIEW)
+#endif // defined(BOOST_ASIO_HAS_STRING_VIEW)
 
     // address_v4 I/O.