Added new example.

CMakeLists.txt

@@ -88,17 +88,22 @@ IF (MSGPACK_32BIT)
    ENDIF ()
 ENDIF ()
 
+OPTION (MSGPACK_BUILD_EXAMPLES "Build msgpack examples." ON)
+
 IF (MSGPACK_BOOST)
    SET (CMAKE_CXX_FLAGS "-DMSGPACK_USE_BOOST ${CMAKE_CXX_FLAGS}")
+ENDIF ()
+
 SET (Boost_USE_STATIC_LIBS        ON) # only find static libs
 SET (Boost_USE_MULTITHREADED      ON)
 SET (Boost_USE_STATIC_RUNTIME    OFF)
-   FIND_PACKAGE (Boost COMPONENTS chrono timer system)
+FIND_PACKAGE (Boost COMPONENTS chrono context timer system)
 IF (Boost_INCLUDE_DIRS)
     INCLUDE_DIRECTORIES (
         ${Boost_INCLUDE_DIRS}
     )
 ENDIF ()
+IF (MSGPACK_BOOST_DIR)
     INCLUDE_DIRECTORIES (
         ${MSGPACK_BOOST_DIR}
     )
@@ -141,7 +146,6 @@ FIND_PACKAGE (Threads)
 IF (GTEST_FOUND AND ZLIB_FOUND AND THREADS_FOUND)
     OPTION (MSGPACK_BUILD_TESTS "Build msgpack tests." ON)
 ENDIF ()
-OPTION (MSGPACK_BUILD_EXAMPLES "Build msgpack examples." ON)
 
 OPTION (MSGPACK_ENABLE_CXX "Enable C++ interface." ON)
 OPTION (MSGPACK_ENABLE_SHARED "Build shared libaries in addition to static libraries." ON)

example/CMakeLists.txt

@@ -2,3 +2,4 @@ ADD_SUBDIRECTORY (c)
 ADD_SUBDIRECTORY (cpp03)
 ADD_SUBDIRECTORY (cpp11)
 ADD_SUBDIRECTORY (boost)
+ADD_SUBDIRECTORY (x3)

example/cpp03/CMakeLists.txt

@@ -22,14 +22,12 @@ IF (NOT MSVC)
     )
 ENDIF ()
 
-IF (MSGPACK_BOOST)
+IF (Boost_TIMER_LIBRARY AND Boost_CHRONO_LIBRARY AND Boost_SYSTEM_LIBRARY)
-    IF (NOT MSVC)
     LIST (APPEND with_boost_lib_PROGRAMS
         speed_test.cpp
         speed_test_nested_array.cpp
     )
 ENDIF ()
-ENDIF ()
 
 FOREACH (source_file ${exec_PROGRAMS})
     GET_FILENAME_COMPONENT (source_file_we ${source_file} NAME_WE)
@@ -56,10 +54,10 @@ FOREACH (source_file ${with_pthread_PROGRAMS})
         ${source_file}
     )
     TARGET_LINK_LIBRARIES (${source_file_we}
-        pthread
+        ${CMAKE_THREAD_LIBS_INIT}
     )
     IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-        SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS "-Wall -Wextra -Werror -g -O3 -pthread")
+        SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS "-Wall -Wextra -Werror -g -O3")
     ENDIF ()
     IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
         IF (CMAKE_CXX_FLAGS MATCHES "/W[0-4]")

example/x3/CMakeLists.txt

@@ -0,0 +1,64 @@
+IF (MSGPACK_USE_X3_PARSE)
+    INCLUDE_DIRECTORIES (
+        ../include
+    )
+
+    LIST (APPEND exec_PROGRAMS
+        unpack.cpp
+        parse.cpp
+    )
+    IF (Boost_CONTEXT_LIBRARY AND Boost_SYSTEM_LIBRARY AND CMAKE_THREAD_LIBS_INIT)
+        LIST (APPEND with_boost_PROGRAMS
+            stream_unpack.cpp
+        )
+    ENDIF ()
+    FOREACH (source_file ${exec_PROGRAMS})
+        GET_FILENAME_COMPONENT (source_file_we ${source_file} NAME_WE)
+        ADD_EXECUTABLE (
+            ${source_file_we}
+            ${source_file}
+        )
+        IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+            SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS "-Wall -Wextra -Werror -g ")
+        ENDIF ()
+
+        IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+            SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS " -Wno-mismatched-tags")
+        ENDIF ()
+
+        IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
+            IF (CMAKE_CXX_FLAGS MATCHES "/W[0-4]")
+                STRING(REGEX REPLACE "/W[0-4]" "/W3 /WX" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+            ELSE ()
+                SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W3 /WX")
+            ENDIF ()
+        ENDIF ()
+    ENDFOREACH ()
+    FOREACH (source_file ${with_boost_PROGRAMS})
+        GET_FILENAME_COMPONENT (source_file_we ${source_file} NAME_WE)
+        ADD_EXECUTABLE (
+            ${source_file_we}
+            ${source_file}
+        )
+        TARGET_LINK_LIBRARIES (${source_file_we}
+            ${Boost_CONTEXT_LIBRARY}
+            ${Boost_SYSTEM_LIBRARY}
+            ${CMAKE_THREAD_LIBS_INIT}
+        )
+        IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+            SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS "-Wall -Wextra -Werror -g ")
+        ENDIF ()
+
+        IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "Clang")
+            SET_PROPERTY (TARGET ${source_file_we} APPEND_STRING PROPERTY COMPILE_FLAGS " -Wno-mismatched-tags")
+        ENDIF ()
+
+        IF ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "MSVC")
+            IF (CMAKE_CXX_FLAGS MATCHES "/W[0-4]")
+                STRING(REGEX REPLACE "/W[0-4]" "/W3 /WX" CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS}")
+            ELSE ()
+                SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} /W3 /WX")
+            ENDIF ()
+        ENDIF ()
+    ENDFOREACH ()
+ENDIF ()

example/x3/parse.cpp

@@ -0,0 +1,119 @@
+// MessagePack for C++ example
+//
+// Copyright (C) 2017 KONDO Takatoshi
+//
+//    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)
+//
+
+#include <iostream>
+#include <sstream>
+#include <cassert>
+
+// MSGPACK_USE_X3_PARSE should be defined before including msgpack.hpp
+// It usually defined as a compiler option as -DMSGPACK_USE_X3_PARSE.
+
+#include <msgpack.hpp>
+
+struct json_like_visitor : msgpack::v2::null_visitor {
+    json_like_visitor(std::string& s):m_s(s) {}
+
+    bool visit_nil() {
+        m_s += "null";
+        return true;
+    }
+    bool visit_boolean(bool v) {
+        if (v) m_s += "true";
+        else m_s += "false";
+        return true;
+    }
+    bool visit_positive_integer(uint64_t v) {
+        std::stringstream ss;
+        ss << v;
+        m_s += ss.str();
+        return true;
+    }
+    bool visit_negative_integer(int64_t v) {
+        std::stringstream ss;
+        ss << v;
+        m_s += ss.str();
+        return true;
+    }
+    bool visit_float(double v) {
+        std::stringstream ss;
+        ss << v;
+        m_s += ss.str();
+        return true;
+    }
+    bool visit_str(const char* v, uint32_t size) {
+        m_s += '"' + std::string(v, size) + '"';
+        return true;
+    }
+    bool start_array(uint32_t /*num_elements*/) {
+        m_s += "[";
+        return true;
+    }
+    bool end_array_item() {
+        m_s += ",";
+        return true;
+    }
+    bool end_array() {
+        m_s.erase(m_s.size() - 1, 1); // remove the last ','
+        m_s += "]";
+        return true;
+    }
+    bool start_map(uint32_t /*num_kv_pairs*/) {
+        m_s += "{";
+        return true;
+    }
+    bool end_map_key() {
+        m_s += ":";
+        return true;
+    }
+    bool end_map_value() {
+        m_s += ",";
+        return true;
+    }
+    bool end_map() {
+        m_s.erase(m_s.size() - 1, 1); // remove the last ','
+        m_s += "}";
+        return true;
+    }
+    void parse_error(size_t /*parsed_offset*/, size_t /*error_offset*/) {
+    }
+    void insufficient_bytes(size_t /*parsed_offset*/, size_t /*error_offset*/) {
+    }
+    std::string& m_s;
+};
+
+int main() {
+    std::stringstream ss;
+    std::map<std::string, std::vector<int>> v1 {
+        { "ABC", { 1, 2, 3 } },
+        { "DEFG", { 4, 5 } }
+    };
+    std::vector<std::string> v2 {
+        "HIJ", "KLM", "NOP"
+    };
+    msgpack::pack(ss, v1);
+    msgpack::pack(ss, v2);
+
+    std::string const& buf = ss.str();
+    auto it = buf.begin();
+    auto end = buf.end();
+    {
+        std::string str;
+        bool ret = msgpack::parse(it, end, json_like_visitor(str));
+        // it is updated here.
+        assert(ret);
+        std::cout << str << std::endl;
+    }
+    {
+        std::string str;
+        bool ret = msgpack::parse(it, end, json_like_visitor(str));
+        // it is updated here.
+        assert(ret);
+        std::cout << str << std::endl;
+    }
+}

example/x3/stream_unpack.cpp

@@ -0,0 +1,239 @@
+// MessagePack for C++ example
+//
+// Copyright (C) 2017 KONDO Takatoshi
+//
+//    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)
+//
+
+#include <iostream>
+#include <sstream>
+#include <cassert>
+#include <thread>
+
+// MSGPACK_USE_X3_PARSE should be defined before including msgpack.hpp
+// It usually defined as a compiler option as -DMSGPACK_USE_X3_PARSE.
+
+//#define MSGPACK_USE_X3_PARSE
+
+#include <msgpack.hpp>
+
+#include <boost/asio.hpp>
+#include <boost/coroutine2/all.hpp>
+#include <boost/spirit/home/support/multi_pass.hpp>
+
+
+namespace as = boost::asio;
+namespace x3 = boost::spirit::x3;
+namespace coro2 = boost::coroutines2;
+
+using pull_type = coro2::asymmetric_coroutine<std::shared_ptr<std::vector<char>>>::pull_type;
+
+// iterator fetching data from coroutine2.
+class buffered_iterator : public std::iterator<std::input_iterator_tag, char> {
+public:
+    using pointer_t = typename iterator::pointer;
+    using reference_t = typename iterator::reference;
+
+    explicit buffered_iterator(pull_type& source) noexcept
+        : source_{ &source } {
+        fetch_();
+    }
+    buffered_iterator() = default;
+
+    bool operator==(buffered_iterator const& other) const noexcept {
+        if (!other.source_ && !source_ && !other.buf_ && !buf_) return true;
+        return other.it_ == it_;
+    }
+
+    bool operator!=(buffered_iterator const& other) const noexcept {
+        return !(other == *this);
+    }
+
+    buffered_iterator & operator++() {
+        increment_();
+        return * this;
+    }
+
+    buffered_iterator operator++(int) = delete;
+
+    reference_t operator*() noexcept {
+        return *it_;
+    }
+
+    pointer_t operator->() noexcept {
+        return std::addressof(*it_);
+    }
+
+private:
+    void fetch_() noexcept {
+        BOOST_ASSERT( nullptr != source_);
+        if (*source_) {
+            buf_ = source_->get();
+            it_ = buf_->begin();
+        }
+        else {
+            source_ = nullptr;
+            buf_.reset();
+        }
+    }
+
+    void increment_() {
+        BOOST_ASSERT( nullptr != source_);
+        BOOST_ASSERT(*source_);
+        if (++it_ == buf_->end()) {
+            (*source_)();
+            fetch_();
+        }
+    }
+
+private:
+    pull_type* source_{ nullptr };
+    std::shared_ptr<std::vector<char>> buf_;
+    std::vector<char>::iterator it_;
+};
+
+// session class that corresponding to each client
+class session : public std::enable_shared_from_this<session> {
+public:
+    session(as::ip::tcp::socket socket)
+        : socket_(std::move(socket)) {
+    }
+
+    void start() {
+        sink_ = std::make_shared<coro2::asymmetric_coroutine<std::shared_ptr<std::vector<char>>>::push_type>(
+            [&, this](pull_type& source) {
+                // *1 is started when the first sink is called.
+
+                std::cout << "session started" << std::endl;
+                do_read();
+                source();
+
+                // use buffered_iterator here
+                // b is incremented in msgpack::unpack() and fetch data from sink
+                // via coroutine2 mechanism
+                auto b = boost::spirit::make_default_multi_pass(buffered_iterator(source));
+                auto e = boost::spirit::make_default_multi_pass(buffered_iterator());
+
+                // This is usually an infinity look, but for test, loop is finished when
+                // two message pack data is processed.
+                for (int i = 0; i != 2; ++i) {
+                    auto oh = msgpack::unpack(b, e);
+                    std::cout << oh.get() << std::endl;
+                }
+            }
+        );
+        // send dummy data to start *1
+        (*sink_)({});
+    }
+
+private:
+    void do_read() {
+        std::cout << "session do_read() is called" << std::endl;
+        auto self(shared_from_this());
+        auto data = std::make_shared<std::vector<char>>(static_cast<std::size_t>(max_length));
+        socket_.async_read_some(
+            boost::asio::buffer(*data),
+            [this, self, data]
+            (boost::system::error_code ec, std::size_t length) {
+                if (!ec) {
+                    data->resize(length);
+                    (*sink_)(data);
+                    do_read();
+                }
+            }
+        );
+    }
+
+    as::ip::tcp::socket socket_;
+    static constexpr std::size_t const max_length = 1024;
+    std::shared_ptr<coro2::asymmetric_coroutine<std::shared_ptr<std::vector<char>>>::push_type> sink_;
+};
+
+class server {
+public:
+    server(
+        as::io_service& ios,
+        std::uint16_t port)
+        : acceptor_(ios, as::ip::tcp::endpoint(as::ip::tcp::v4(), port)),
+          socket_(ios) {
+        do_accept();
+        std::cout << "server start accept" << std::endl;
+        ios.run();
+    }
+
+private:
+    void do_accept() {
+        acceptor_.async_accept(
+            socket_,
+            [this](boost::system::error_code ec) {
+                if (!ec) {
+                    std::make_shared<session>(std::move(socket_))->start();
+                }
+                // for test, only one session is accepted.
+                // do_accept();
+            }
+        );
+    }
+
+    as::ip::tcp::acceptor acceptor_;
+    as::ip::tcp::socket socket_;
+};
+
+int main() {
+    std::thread srv(
+        []{
+            boost::asio::io_service ios;
+            server s(ios, 12345);
+        }
+    );
+
+    std::thread cli(
+        []{
+            std::this_thread::sleep_for(std::chrono::seconds(1));
+            std::cout << "client start" << std::endl;
+
+            std::stringstream ss;
+            std::map<std::string, std::vector<int>> v1 {
+                { "ABC", { 1, 2, 3 } },
+                { "DEFG", { 4, 5 } }
+            };
+            std::vector<std::string> v2 {
+                "HIJ", "KLM", "NOP"
+                    };
+            msgpack::pack(ss, v1);
+            msgpack::pack(ss, v2);
+
+            auto send_data = ss.str();
+
+            boost::asio::io_service ios;
+            as::ip::tcp::resolver::query q("127.0.0.1", "12345");
+            as::ip::tcp::resolver r(ios);
+            auto it = r.resolve(q);
+
+            std::cout << "client connect" << std::endl;
+            as::ip::tcp::socket s(ios);
+            as::connect(s, it);
+
+
+            std::size_t const size = 5;
+            std::size_t rest = send_data.size();
+            std::size_t index = 0;
+            while (rest != 0) {
+                std::cout << "client send data" << std::endl;
+                auto send_size = size < rest ? size : rest;
+                as::write(s, as::buffer(&send_data[index], send_size));
+                rest -= send_size;
+                index += send_size;
+                std::cout << "client wait" << std::endl;
+                std::this_thread::sleep_for(std::chrono::seconds(1));
+            }
+        }
+    );
+
+    cli.join();
+    std::cout << "client joinded" << std::endl;
+    srv.join();
+    std::cout << "server joinded" << std::endl;
+}

example/x3/unpack.cpp

@@ -0,0 +1,43 @@
+// MessagePack for C++ example
+//
+// Copyright (C) 2017 KONDO Takatoshi
+//
+//    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)
+//
+
+#include <iostream>
+#include <sstream>
+#include <cassert>
+
+// MSGPACK_USE_X3_PARSE should be defined before including msgpack.hpp
+// It usually defined as a compiler option as -DMSGPACK_USE_X3_PARSE.
+
+#include <msgpack.hpp>
+
+int main() {
+    std::stringstream ss;
+    std::map<std::string, std::vector<int>> v1 {
+        { "ABC", { 1, 2, 3 } },
+        { "DEFG", { 4, 5 } }
+    };
+    std::vector<std::string> v2 {
+        "HIJ", "KLM", "NOP"
+    };
+    msgpack::pack(ss, v1);
+    msgpack::pack(ss, v2);
+
+    std::string const& buf = ss.str();
+    auto it = buf.begin();
+    auto end = buf.end();
+    {
+        auto oh = msgpack::unpack(it, end);
+        // it is updated here.
+        assert(v1 == (oh.get().as<std::map<std::string, std::vector<int>>>()));
+    }
+    {
+        auto oh = msgpack::unpack(it, end);
+        assert(v2 == oh.get().as<std::vector<std::string>>());
+    }
+}

include/msgpack/v2/x3_parse.hpp

@@ -340,7 +340,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& str = _attr(ctx);
-                app_specific.vis.visit_str(str.size() ? &str[0] : nullptr, str.size());
+                std::size_t size = std::distance(str.begin(), str.end());
+                app_specific.vis.visit_str(size ? &str.front() : nullptr, size);
             }
         )
     ]
@@ -363,7 +364,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& str = _attr(ctx);
-                app_specific.vis.visit_str(str.size() ? &str[0] : nullptr, str.size());
+                std::size_t size = std::distance(str.begin(), str.end());
+                app_specific.vis.visit_str(size ? &str.front() : nullptr, size);
             }
         )
     ]
@@ -386,7 +388,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& str = _attr(ctx);
-                app_specific.vis.visit_str(str.size() ? &str[0] : nullptr, str.size());
+                std::size_t size = std::distance(str.begin(), str.end());
+                app_specific.vis.visit_str(size ? &str.front() : nullptr, size);
             }
         )
     ]
@@ -409,7 +412,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& str = _attr(ctx);
-                app_specific.vis.visit_str(str.size() ? &str[0] : nullptr, str.size());
+                std::size_t size = std::distance(str.begin(), str.end());
+                app_specific.vis.visit_str(size ? &str.front() : nullptr, size);
             }
         )
     ]
@@ -432,7 +436,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& bin = _attr(ctx);
-                app_specific.vis.visit_bin(bin.size() ? &bin[0] : nullptr, bin.size());
+                std::size_t size = std::distance(bin.begin(), bin.end());
+                app_specific.vis.visit_bin(size ? &bin.front() : nullptr, size);
             }
         )
     ]
@@ -455,7 +460,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& bin = _attr(ctx);
-                app_specific.vis.visit_bin(bin.size() ? &bin[0] : nullptr, bin.size());
+                std::size_t size = std::distance(bin.begin(), bin.end());
+                app_specific.vis.visit_bin(size ? &bin.front() : nullptr, size);
             }
         )
     ]
@@ -478,7 +484,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& bin = _attr(ctx);
-                app_specific.vis.visit_bin(bin.size() ? &bin[0] : nullptr, bin.size());
+                std::size_t size = std::distance(bin.begin(), bin.end());
+                app_specific.vis.visit_bin(size ? &bin.front() : nullptr, size);
             }
         )
     ]
@@ -585,7 +592,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ]
@@ -608,7 +616,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ]
@@ -631,7 +640,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ]
@@ -654,7 +664,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ]
@@ -677,7 +688,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ]
@@ -700,7 +712,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ]
@@ -723,7 +736,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ]
@@ -746,7 +760,8 @@ const auto mp_object_def =
             [](auto& ctx){
                 auto& app_specific = x3::get<tag_app_specific>(ctx).get();
                 auto const& ext = _attr(ctx);
-                app_specific.vis.visit_ext(ext.size() ? &ext[0] : nullptr, ext.size());
+                std::size_t size = std::distance(ext.begin(), ext.end());
+                app_specific.vis.visit_ext(size ? &ext.front() : nullptr, size);
             }
         )
     ];