Fix include guard in adapt_assoc_adt.hpp (#273)

Update 5 adds /Zc:templateScope flag which causes compile errors in
typedefs redefining template parameters.

.github/workflows/ci.yml

@@ -0,0 +1,471 @@
+name: GitHub Actions CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+      - develop
+      - githubactions*
+      - feature/**
+      - fix/**
+      - pr/**
+
+jobs:
+  posix:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: "TOOLSET=gcc-4.4 CXXSTD=98,0x Job 0"
+            buildtype: "boost"
+            packages: "g++-4.4"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-4.4"
+            cxxstd: "98,0x"
+          - name: "TOOLSET=gcc-4.6 CXXSTD=03,0x Job 1"
+            buildtype: "boost"
+            packages: "g++-4.6"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-4.6"
+            cxxstd: "03,0x"
+          - name: "TOOLSET=gcc-4.7 CXXSTD=03,11 Job 2"
+            buildtype: "boost"
+            packages: "g++-4.7"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-4.7"
+            cxxstd: "03,11"
+          - name: "TOOLSET=gcc-4.8 CXXSTD=03,11,1y Job 3"
+            buildtype: "boost"
+            packages: "g++-4.8"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-4.8"
+            cxxstd: "03,11,1y"
+          - name: "TOOLSET=gcc-4.9 CXXSTD=03,11,14 Job 4"
+            buildtype: "boost"
+            packages: "g++-4.9"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-4.9"
+            cxxstd: "03,11,14"
+          - name: "TOOLSET=gcc-5 CXXSTD=03,11,14,17 Job 5"
+            buildtype: "boost"
+            packages: "g++-5"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-5"
+            cxxstd: "03,11,14,17"
+          - name: "TOOLSET=gcc-6 CXXSTD=03,11,14,17 Job 6"
+            buildtype: "boost"
+            packages: "g++-6"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-6"
+            cxxstd: "03,11,14,17"
+          - name: "TOOLSET=gcc-7 CXXSTD=03,11,14,17 Job 7"
+            buildtype: "boost"
+            packages: "g++-7"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-7"
+            cxxstd: "03,11,14,17"
+          - name: "TOOLSET=gcc-8 CXXSTD=03,11,14,17,2a Job 8"
+            buildtype: "boost"
+            packages: "g++-8"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "gcc-8"
+            cxxstd: "03,11,14,17,2a"
+          - name: "TOOLSET=clang-3.5 CXXSTD=03,11,14,1z Job 9"
+            buildtype: "boost"
+            packages: "clang-3.5"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "clang-3.5"
+            cxxstd: "03,11,14"
+          - name: "TOOLSET=clang-3.6 CXXSTD=03,11,14,1z Job 10"
+            buildtype: "boost"
+            packages: "clang-3.6"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "clang-3.6"
+            cxxstd: "03,11,14"
+          - name: "TOOLSET=clang-3.7 CXXSTD=03,11,14,1z Job 11"
+            buildtype: "boost"
+            packages: "clang-3.7"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "clang-3.7"
+            cxxstd: "03,11,14"
+          - name: "TOOLSET=clang-3.8 CXXSTD=03,11,14,1z Job 12"
+            buildtype: "boost"
+            packages: "clang-3.8"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "clang-3.8"
+            cxxstd: "03,11,14"
+          - name: "TOOLSET=clang-3.9 CXXSTD=03,11,14,1z Job 13"
+            buildtype: "boost"
+            packages: "clang-3.9"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "clang-3.9"
+            cxxstd: "03,11,14"
+          - name: "TOOLSET=clang-4.0 CXXSTD=03,11,14,1z Job 14"
+            buildtype: "boost"
+            packages: "clang-4.0"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            toolset: "clang-4.0"
+            cxxstd: "03,11,14"
+          - name: "TOOLSET=clang-5.0 CXXSTD=03,11,14,17,2a Job 15"
+            buildtype: "boost"
+            packages: "clang-5.0"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: "xenial"
+            llvm_ver: "5.0"
+            toolset: "clang-5.0"
+            cxxstd: "03,11,14,17,2a"
+          - name: "TOOLSET=clang-6.0 CXXSTD=03,11,14,17,2a Job 16"
+            buildtype: "boost"
+            packages: "clang-6.0"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: "xenial"
+            llvm_ver: "6.0"
+            toolset: "clang-6.0"
+            cxxstd: "03,11,14,17,2a"
+          - name: "TOOLSET=clang-7 CXXSTD=03,11,14,17,2a Job 17"
+            buildtype: "boost"
+            packages: "clang-7"
+            packages_to_remove: ""
+            os: "ubuntu-20.04"
+            container: "ubuntu:16.04"
+            cxx: "g++"
+            sources: ""
+            llvm_os: "xenial"
+            llvm_ver: "7"
+            toolset: "clang-7"
+            cxxstd: "03,11,14,17,2a"
+
+    runs-on: ${{ matrix.os }}
+    container: ${{ matrix.container }}
+
+    steps:
+      - name: Check if running in container
+        if: matrix.container != ''
+        run: echo "GHA_CONTAINER=${{ matrix.container }}" >> $GITHUB_ENV
+      - name: If running in container, upgrade packages
+        if: matrix.container != ''
+        run: |
+            apt-get -o Acquire::Retries=3 update && DEBIAN_FRONTEND=noninteractive apt-get -y install tzdata && apt-get -o Acquire::Retries=3 install -y sudo software-properties-common wget curl apt-transport-https make apt-file sudo unzip libssl-dev build-essential autotools-dev autoconf automake g++ libc++-helpers python ruby cpio gcc-multilib g++-multilib pkgconf python3 ccache libpython-dev
+            sudo apt-add-repository ppa:git-core/ppa
+            sudo apt-get -o Acquire::Retries=3 update && apt-get -o Acquire::Retries=3 -y install git
+            python_version=$(python3 -c 'import sys; print("{0.major}.{0.minor}".format(sys.version_info))')
+            sudo wget https://bootstrap.pypa.io/pip/$python_version/get-pip.py
+            sudo python3 get-pip.py
+            sudo /usr/local/bin/pip install cmake
+
+      - uses: actions/checkout@v2
+
+      - name: linux
+        shell: bash
+        env:
+          CXX: ${{ matrix.cxx }}
+          SOURCES: ${{ matrix.sources }}
+          LLVM_OS: ${{ matrix.llvm_os }}
+          LLVM_VER: ${{ matrix.llvm_ver }}
+          PACKAGES: ${{ matrix.packages }}
+          PACKAGES_TO_REMOVE: ${{ matrix.packages_to_remove }}
+          JOB_BUILDTYPE: ${{ matrix.buildtype }}
+          TOOLSET: ${{ matrix.toolset }}
+          CXXSTD: ${{ matrix.cxxstd }}
+          COMPILER: ${{ matrix.compiler }}
+          TRAVIS_BRANCH: ${{ github.base_ref }}
+          TRAVIS_OS_NAME: "linux"
+        run: |
+          echo '==================================> SETUP'
+          echo '==================================> PACKAGES'
+          set -e
+          if [ -n "$PACKAGES_TO_REMOVE" ]; then sudo apt-get purge -y $PACKAGES_TO_REMOVE; fi
+          echo ">>>>> APT: REPO.."
+          for i in {1..3}; do sudo -E apt-add-repository -y "ppa:ubuntu-toolchain-r/test" && break || sleep 2; done
+          
+          if test -n "${LLVM_OS}" ; then
+              wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+              if test -n "${LLVM_VER}" ; then
+                  sudo -E apt-add-repository "deb http://apt.llvm.org/${LLVM_OS}/ llvm-toolchain-${LLVM_OS}-${LLVM_VER} main"
+              else
+                  # Snapshot (i.e. trunk) build of clang
+                  sudo -E apt-add-repository "deb http://apt.llvm.org/${LLVM_OS}/ llvm-toolchain-${LLVM_OS} main"
+              fi
+          fi
+          echo ">>>>> APT: UPDATE.."
+          sudo -E apt-get -o Acquire::Retries=3 update
+          if test -n "${SOURCES}" ; then
+              echo ">>>>> APT: INSTALL SOURCES.."
+              for SOURCE in $SOURCES; do
+                  sudo -E apt-add-repository ppa:$SOURCE
+              done
+          fi
+          echo ">>>>> APT: INSTALL ${PACKAGES}.."
+          sudo -E DEBIAN_FRONTEND=noninteractive apt-get -o Acquire::Retries=3 -y --no-install-suggests --no-install-recommends install ${PACKAGES}
+
+          echo '==================================> INSTALL AND COMPILE'
+          set -e
+          export TRAVIS_BUILD_DIR=$(pwd)
+          export TRAVIS_BRANCH=${TRAVIS_BRANCH:-$(echo $GITHUB_REF | awk 'BEGIN { FS = "/" } ; { print $3 }')}
+          export VCS_COMMIT_ID=$GITHUB_SHA
+          export GIT_COMMIT=$GITHUB_SHA
+          export REPO_NAME=$(basename $GITHUB_REPOSITORY)
+          export USER=$(whoami)
+          export CC=${CC:-gcc}
+          export PATH=~/.local/bin:/usr/local/bin:$PATH
+
+          if [ "$JOB_BUILDTYPE" == "boost" ]; then
+
+          echo '==================================> INSTALL'
+
+          BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+          cd ..
+          git clone --depth 1 -b $BOOST_BRANCH https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          git submodule init libs/array
+          git submodule init libs/assert
+          git submodule init libs/bind
+          git submodule init libs/concept_check
+          git submodule init libs/config
+          git submodule init libs/container_hash
+          git submodule init libs/conversion
+          git submodule init libs/core
+          git submodule init libs/detail
+          git submodule init libs/function
+          git submodule init libs/function_types
+          git submodule init libs/functional
+          git submodule init libs/integer
+          git submodule init libs/iterator
+          git submodule init libs/lambda
+          git submodule init libs/move
+          git submodule init libs/mpl
+          git submodule init libs/optional
+          git submodule init libs/predef
+          git submodule init libs/preprocessor
+          git submodule init libs/smart_ptr
+          git submodule init libs/static_assert
+          git submodule init libs/throw_exception
+          git submodule init libs/tuple
+          git submodule init libs/type_index
+          git submodule init libs/type_traits
+          git submodule init libs/typeof
+          git submodule init libs/utility
+          git submodule init libs/describe
+          git submodule init libs/mp11
+          git submodule init libs/headers tools/boost_install tools/build
+          git submodule update
+          rm -rf libs/fusion
+          cp -rp $TRAVIS_BUILD_DIR libs/fusion
+          ln -s $(pwd)/libs/fusion $TRAVIS_BUILD_DIR
+          ./bootstrap.sh
+          ./b2 headers
+
+          echo '==================================> SCRIPT'
+
+          ./b2 -j`(nproc || sysctl -n hw.ncpu) 2> /dev/null` libs/fusion/test toolset=$TOOLSET cxxstd=$CXXSTD
+
+          fi
+  osx:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - name: "TOOLSET=clang COMPILER=clang++ CXXSTD=03,11,1 Job 18"
+            buildtype: "boost"
+            packages: ""
+            os: "macos-10.15"
+            cxx: "clang++"
+            sources: ""
+            llvm_os: ""
+            llvm_ver: ""
+            xcode_version: 11.7
+            toolset: "clang"
+            compiler: "clang++"
+            cxxstd: "03,11,14,1z"
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set DEVELOPER_DIR
+        if: matrix.xcode_version != ''
+        run: echo "DEVELOPER_DIR=/Applications/Xcode_${{ matrix.xcode_version }}.app/Contents/Developer" >> $GITHUB_ENV
+      - name: Test DEVELOPER_DIR
+        run: echo $DEVELOPER_DIR
+
+      - name: "osx"
+        shell: bash
+        env:
+          CXX: ${{ matrix.cxx }}
+          SOURCES: ${{ matrix.sources }}
+          LLVM_OS: ${{ matrix.llvm_os }}
+          LLVM_VER: ${{ matrix.llvm_ver }}
+          PACKAGES: ${{ matrix.packages }}
+          JOB_BUILDTYPE: ${{ matrix.buildtype }}
+          TOOLSET: ${{ matrix.toolset }}
+          CXXSTD: ${{ matrix.cxxstd }}
+          COMPILER: ${{ matrix.compiler }}
+          TRAVIS_BRANCH: ${{ github.base_ref }}
+          TRAVIS_OS_NAME: "osx"
+        run: |
+          echo '==================================> SETUP'
+          set -e
+          sudo mv /Library/Developer/CommandLineTools /Library/Developer/CommandLineTools.bck
+          echo '==================================> PACKAGES'
+          echo '==================================> INSTALL AND COMPILE'
+          set -e
+          export TRAVIS_BUILD_DIR=$(pwd)
+          export TRAVIS_BRANCH=${TRAVIS_BRANCH:-$(echo $GITHUB_REF | awk 'BEGIN { FS = "/" } ; { print $3 }')}
+          export VCS_COMMIT_ID=$GITHUB_SHA
+          export GIT_COMMIT=$GITHUB_SHA
+          export REPO_NAME=$(basename $GITHUB_REPOSITORY)
+          export USER=$(whoami)
+          export CC=${CC:-gcc}
+          export PATH=~/.local/bin:/usr/local/bin:$PATH
+
+          if [ "$JOB_BUILDTYPE" == "boost" ]; then
+
+          echo '==================================> INSTALL'
+
+          BOOST_BRANCH=develop && [ "$TRAVIS_BRANCH" == "master" ] && BOOST_BRANCH=master || true
+          cd ..
+          git clone --depth 1 -b $BOOST_BRANCH https://github.com/boostorg/boost.git boost-root
+          cd boost-root
+          git submodule init libs/array
+          git submodule init libs/assert
+          git submodule init libs/bind
+          git submodule init libs/concept_check
+          git submodule init libs/config
+          git submodule init libs/container_hash
+          git submodule init libs/conversion
+          git submodule init libs/core
+          git submodule init libs/detail
+          git submodule init libs/function
+          git submodule init libs/function_types
+          git submodule init libs/functional
+          git submodule init libs/integer
+          git submodule init libs/iterator
+          git submodule init libs/lambda
+          git submodule init libs/move
+          git submodule init libs/mpl
+          git submodule init libs/optional
+          git submodule init libs/predef
+          git submodule init libs/preprocessor
+          git submodule init libs/smart_ptr
+          git submodule init libs/static_assert
+          git submodule init libs/throw_exception
+          git submodule init libs/tuple
+          git submodule init libs/type_index
+          git submodule init libs/type_traits
+          git submodule init libs/typeof
+          git submodule init libs/utility
+          git submodule init libs/describe
+          git submodule init libs/mp11
+          git submodule init libs/headers tools/boost_install tools/build
+          git submodule update
+          rm -rf libs/fusion
+          cp -rp $TRAVIS_BUILD_DIR libs/fusion
+          ln -s $(pwd)/libs/fusion $TRAVIS_BUILD_DIR
+          ./bootstrap.sh
+          ./b2 headers
+
+          echo '==================================> SCRIPT'
+
+          ./b2 -j`(nproc || sysctl -n hw.ncpu) 2> /dev/null` libs/fusion/test toolset=$TOOLSET cxxstd=$CXXSTD
+
+          fi

CMakeLists.txt

@@ -23,4 +23,7 @@ target_link_libraries(boost_fusion
         Boost::type_traits
         Boost::typeof
         Boost::utility
+        Boost::functional
+        Boost::describe
+        Boost::mp11
 )

appveyor.yml

@@ -11,15 +11,19 @@ environment:
   matrix:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       TOOLSET: msvc-9.0
+      ADDRMD: 32
       CXXSTD: latest # fake
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       TOOLSET: msvc-10.0
+      ADDRMD: 32
       CXXSTD: latest # fake
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       TOOLSET: msvc-11.0
+      ADDRMD: 32
       CXXSTD: latest # fake
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       TOOLSET: msvc-12.0
+      ADDRMD: 32
       CXXSTD: latest # fake
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2015
       TOOLSET: msvc-14.0
@@ -78,6 +82,8 @@ install:
   - git submodule init libs/type_traits
   - git submodule init libs/typeof
   - git submodule init libs/utility
+  - git submodule init libs/describe
+  - git submodule init libs/mp11
 
   - git submodule init libs/headers tools/boost_install tools/build
   - git submodule update
@@ -88,4 +94,5 @@ install:
 build: off
 
 test_script:
-  - b2 -j%NUMBER_OF_PROCESSORS% --hash libs/fusion/test toolset=%TOOLSET% cxxstd=%CXXSTD%
+  - if not "%ADDRMD%" == "" set ADDRMD=address-model=%ADDRMD%
+  - b2 -j%NUMBER_OF_PROCESSORS% --hash libs/fusion/test toolset=%TOOLSET% cxxstd=%CXXSTD% %ADDRMD%

doc/container.qbk

@@ -1016,8 +1016,8 @@ __note_ref_wrappers__, __fusion_pair__
 
 [section Tiers]
 
-Tiers are sequences, where all elements are non-const reference types. They
-are constructed with a call to a couple of /tie/ function templates. The
+Tiers are sequences, where all elements are reference types. They are
+constructed with a call to a couple of /tie/ function templates. The
 succeeding sections document the various /tier/ flavors.
 
 * __list_tie__
@@ -2005,7 +2005,7 @@ __fusion_pair__s. There may be no duplicate __fusion_pair__ key types.
     as_map(__make_vector__(
         __fusion_make_pair__<int>('X')
       , __fusion_make_pair__<double>("Men")))
-    
+
     // from associative sequence
     namespace ns
     {
@@ -2222,7 +2222,7 @@ __fusion_pair__s. There may be no duplicate __fusion_pair__ key types.
     result_of::as_map<__vector__<
         __fusion_pair__<int, char>
       , __fusion_pair__<double, std::string> > >::type
-    
+
     // from associative sequence
     namespace ns
     {

doc/fusion.qbk

@@ -130,6 +130,7 @@
 [def __reverse_view__           [link fusion.view.reverse_view `reverse_view`]]
 [def __zip_view__               [link fusion.view.zip_view `zip_view`]]
 [def __flatten_view__           [link fusion.view.flatten_view `flatten_view`]]
+[def __identity_view__          [link fusion.view.identity_view `identity_view`]]
 
 [def __array__                  [link fusion.adapted.array array]]
 [def __std_pair__               [link fusion.adapted.std__pair `std::pair`]]

doc/html/index.html

@@ -163,6 +163,7 @@
 <dt><span class="section"><a href="fusion/view/zip_view.html">zip_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/transform_view.html">transform_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/reverse_view.html">reverse_view</a></span></dt>
+<dt><span class="section"><a href="fusion/view/identity_view.html">identity_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/nview.html">nview</a></span></dt>
 <dt><span class="section"><a href="fusion/view/repetitive_view.html">repetitive_view</a></span></dt>
 <dt><span class="section"><a href="fusion/view/flatten_view.html">flatten_view</a></span></dt>

doc/iterator.qbk

@@ -254,6 +254,7 @@ expressions must be valid:
 * __iterator_range__ iterator (where adapted iterators are __associative_iterator__\ s)
 * __joint_view__ iterator (where adapted sequences are __associative_sequence__\ s and __forward_sequence__\ s)
 * __reverse_view__ iterator (where adapted sequence is an __associative_sequence__ and a __bidirectional_sequence__)
+* __transform_view__ iterator (where adapted sequence is an __associative_sequence__ and a __forward_sequence__)
 
 [endsect]
 

doc/organization.qbk

@@ -60,6 +60,7 @@ link against.
     * single_view
     * transform_view
     * zip_view
+    * identity_view
 * container
     * deque
     * list

doc/sequence.qbk

@@ -166,7 +166,7 @@ Bidirectional Sequence the following must be met:
     [[`__back__(s)`]        [Any type]                      []                      [Constant]]
     [[`__back__(s) = o`]    [Any type]                      [`s` is mutable and
                                                         `e = o`, where `e`
-                                                        is the first element
+                                                        is the last element
                                                         in the sequence, is
                                                         a valid expression.]    [Constant]]
 ]
@@ -237,14 +237,14 @@ any Random Access Sequence the following must be met:
     [[`__at_c__<N>(s)`]     [Any type]                      []                      [Constant]]
     [[`__at_c__<N>(s) = o`] [Any type]                      [`s` is mutable and
                                                         `e = o`, where `e`
-                                                        is the first element
-                                                        in the sequence, is
+                                                        is the N-th element from the beginning
+                                                        of the sequence, is
                                                         a valid expression.]        [Constant]]
     [[`__at__<M>(s)`]       [Any type]                      []                      [Constant]]
     [[`__at__<M>(s) = o`]   [Any type]                      [`s` is mutable and
                                                         `e = o`, where `e`
-                                                        is the first element
-                                                        in the sequence, is
+                                                        is the M-th element from the beginning
+                                                        of the sequence, is
                                                         a valid expression.]        [Constant]]
 ]
 
@@ -321,8 +321,7 @@ For any Associative Sequence the following expressions must be valid:
     [[`__at_key__<K>(s)`]       [Any type]                  []                      [Constant]]
     [[`__at_key__<K>(s) = o`]   [Any type]                  [`s` is mutable and
                                                         `e = o`, where `e`
-                                                        is the first element
-                                                        in the sequence, is
+                                                        is the element associated with K, is
                                                         a valid expression.]    [Constant]]
 ]
 
@@ -361,6 +360,7 @@ you can use `__result_of_value_at_key__<S, K>`.]
 * __iterator_range__ (where adapted iterators are __associative_iterator__\ s)
 * __joint_view__     (where adapted sequences are __associative_sequence__\ s and __forward_sequence__\ s)
 * __reverse_view__   (where adapted sequence is an __associative_sequence__ and a __bidirectional_sequence__)
+* __transform_view__ (where adapted sequence is an __associative_sequence__ and a __forward_sequence__)
 
 [endsect]
 
@@ -714,11 +714,11 @@ Returns the M-th element from the beginning of the sequence.
 [heading Synopsis]
 
     template <typename M, typename Sequence>
-    typename __result_of_at__<Sequence, N>::type
+    typename __result_of_at__<Sequence, M>::type
     at(Sequence& seq);
 
     template <typename M, typename Sequence>
-    typename __result_of_at__<Sequence const, N>::type
+    typename __result_of_at__<Sequence const, M>::type
     at(Sequence const& seq);
 
 [heading Parameters]

doc/view.qbk

@@ -1,6 +1,7 @@
 [/==============================================================================
     Copyright (C) 2001-2011 Joel de Guzman
     Copyright (C) 2006 Dan Marsden
+    Copyright (c) 2022 Denis Mikhailov
 
     Use, modification and distribution is subject to the Boost Software
     License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
@@ -328,9 +329,7 @@ defined in __forward_sequence__.
 The unary version of `transform_view` presents a view of its underlying
 sequence given a unary function object or function pointer. The binary
 version of `transform_view` presents a view of 2 underlying sequences,
-given a binary function object or function pointer. The `transform_view`
-inherits the traversal characteristics (see __traversal_concept__)  of
-its underlying sequence or sequences.
+given a binary function object or function pointer.
 
 [heading Header]
 
@@ -364,7 +363,8 @@ its underlying sequence or sequences.
 
 * __forward_sequence__, __bidirectional_sequence__ or
 __random_access_sequence__ depending on the traversal characteristics (see
-__traversal_concept__) of its underlying sequence.
+__traversal_concept__) of its underlying sequence or sequences.
+* __associative_sequence__ if underlying sequence implements the __associative_sequence__ model(available only with unary version of `transform_view`).
 
 [variablelist Notation
     [[`TV`]             [A `transform_view` type]]
@@ -381,9 +381,7 @@ __traversal_concept__) of its underlying sequence.
 [heading Expression Semantics]
 
 Semantics of an expression is defined only where it differs from, or is not
-defined in __forward_sequence__, __bidirectional_sequence__ or
-__random_access_sequence__ depending on the traversal characteristics (see
-__traversal_concept__) of its underlying sequence or sequences.
+defined in the implemented models.
 
 [table
     [[Expression]           [Semantics]]
@@ -667,4 +665,60 @@ defined in __forward_sequence__.
 
 [endsect]
 
+[section identity_view]
+
+[heading Description]
+
+`identity_view` presents underlying sequence unchanged.
+
+[heading Header]
+
+    #include <boost/fusion/view/identity_view.hpp>
+    #include <boost/fusion/include/identity_view.hpp>
+
+[heading Synopsis]
+
+    template <typename Sequence>
+    struct identity_view;
+
+[heading Template parameters]
+
+[table
+    [[Parameter]            [Description]                   [Default]]
+    [[`Sequence`]           [A __forward_sequence__]        []]
+]
+
+[heading Model of]
+
+* A model of __forward_sequence__ if `Sequence` is a __forward_sequence__ else, __bidirectional_sequence__ if `Sequence` is a __bidirectional_sequence__
+else, __random_access_sequence__ if `Sequence` is a __random_access_sequence__.
+* __associative_sequence__ if `Sequence` implements the __associative_sequence__ model.
+
+[variablelist Notation
+    [[`IV`]             [An `identity_view` type]]
+    [[`s`]              [An instance of `Sequence`]]
+    [[`iv`, `iv2`]      [Instances of `identity_view`]]
+]
+
+[heading Expression Semantics]
+
+Semantics of an expression is defined only where it differs from, or is not
+defined in the implemented models.
+
+[table
+    [[Expression]           [Semantics]]
+    [[`IV(s)`]              [Creates an `identity_view` given sequence, `s`.]]
+    [[`IV(iv)`]             [Copy constructs an `identity_view` from another `identity_view`, `iv`.]]
+    [[`iv = iv2`]           [Assigns to an `identity_view`, `iv`, from another `identity_view`, `iv2`.]]
+]
+
+[heading Example]
+    typedef __vector__<int, short, double> vector_type;
+    vector_type vec(2, 5, 3.3);
+
+    __identity_view__<vector_type> identity(vec);
+    std::cout << identity << std::endl; // (2 5 3.3)
+
+[endsect]
+
 [endsect]

example/cookbook/do_the_bind.cpp

@@ -46,7 +46,7 @@
 #include <boost/mpl/max.hpp>
 #include <boost/mpl/next.hpp>
 
-#include <boost/ref.hpp>
+#include <boost/core/ref.hpp>
 #include <iostream>
 #include <typeinfo>
 

include/boost/fusion/adapted/boost_array/array_iterator.hpp

@@ -18,6 +18,11 @@
 #include <boost/type_traits/is_const.hpp>
 #include <boost/fusion/iterator/iterator_facade.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct random_access_traversal_tag;
@@ -102,11 +107,13 @@ namespace boost { namespace fusion
                 return type();
             }
         };
-
-        BOOST_DELETED_FUNCTION(array_iterator& operator=(array_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/adapted/boost_tuple/boost_tuple_iterator.hpp

@@ -45,6 +45,10 @@ namespace boost { namespace fusion
     template <typename Cons>
     struct boost_tuple_iterator_identity;
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
     template <typename Cons = tuples::null_type>
     struct boost_tuple_iterator
         : iterator_facade<boost_tuple_iterator<Cons>, forward_traversal_tag>
@@ -143,10 +147,10 @@ namespace boost { namespace fusion
         struct equal_to
             : is_same<typename I1::identity, typename I2::identity>
         {};
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(boost_tuple_iterator& operator= (boost_tuple_iterator const&))
     };
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
 
     template <typename Null>
     struct boost_tuple_null_iterator

include/boost/fusion/adapted/std_array/std_array_iterator.hpp

@@ -19,6 +19,11 @@
 #include <boost/fusion/iterator/iterator_facade.hpp>
 #include <boost/fusion/adapted/std_array/detail/array_size.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct random_access_traversal_tag;
@@ -99,9 +104,11 @@ namespace boost { namespace fusion
                 return type();
             }
         };
-
-        BOOST_DELETED_FUNCTION(std_array_iterator& operator=(std_array_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif

include/boost/fusion/adapted/std_tuple/std_tuple_iterator.hpp

@@ -17,6 +17,11 @@
 #include <tuple>
 #include <utility>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct random_access_traversal_tag;
@@ -107,6 +112,10 @@ namespace boost { namespace fusion
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/adapted/struct/detail/adapt_base.hpp

@@ -143,7 +143,7 @@
         I,                                                                      \
         ATTRIBUTE)
 
-#ifdef BOOST_MSVC
+#if defined(BOOST_MSVC) && (BOOST_MSVC < 1935)
 #   define BOOST_FUSION_ADAPT_STRUCT_MSVC_REDEFINE_TEMPLATE_PARAM(R,_,ELEM)     \
         typedef ELEM ELEM;
 #   define BOOST_FUSION_ADAPT_STRUCT_MSVC_REDEFINE_TEMPLATE_PARAMS_IMPL(SEQ)    \

include/boost/fusion/adapted/struct/detail/define_struct_inline.hpp

@@ -326,6 +326,9 @@
 #define BOOST_FUSION_DEFINE_STRUCT_INLINE_ITERATOR_IMPL_IMPL(                   \
     NAME, ATTRIBUTES_SEQ, ATTRIBUTES_SEQ_SIZE)                                  \
                                                                                 \
+    BOOST_FUSION_PUSH_WARNINGS                                                  \
+    BOOST_FUSION_DISABLE_MSVC_WARNING(4512)                                     \
+                                                                                \
     template <typename boost_fusion_detail_Seq, int N>                          \
     struct BOOST_FUSION_ITERATOR_NAME(NAME)                                     \
         : boost::fusion::iterator_facade<                                       \
@@ -418,7 +421,10 @@
                 return type(it.seq_);                                           \
             }                                                                   \
         };                                                                      \
-    };
+    };                                                                          \
+                                                                                \
+    BOOST_FUSION_POP_WARNINGS                                                   \
+    /**/
 
 
 #define BOOST_FUSION_DEFINE_STRUCT_INLINE_MEMBERS_IMPL_IMPL(                    \

include/boost/fusion/adapted/struct/detail/proxy_type.hpp

@@ -19,6 +19,9 @@
                                                                                 \
     BOOST_FUSION_ADAPT_STRUCT_NAMESPACE_DEFINITION_BEGIN(NAMESPACE_SEQ)         \
                                                                                 \
+    BOOST_FUSION_PUSH_WARNINGS                                                  \
+    BOOST_FUSION_DISABLE_MSVC_WARNING(4512)                                     \
+                                                                                \
     struct NAME                                                                 \
     {                                                                           \
         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED                                \
@@ -27,10 +30,10 @@
         {}                                                                      \
                                                                                 \
         WRAPPED_TYPE& obj;                                                      \
-                                                                                \
-        BOOST_DELETED_FUNCTION(NAME& operator= (NAME const&))                   \
     };                                                                          \
                                                                                 \
+    BOOST_FUSION_POP_WARNINGS                                                   \
+                                                                                \
     BOOST_FUSION_ADAPT_STRUCT_NAMESPACE_DEFINITION_END(NAMESPACE_SEQ)
 
 #define BOOST_FUSION_ADAPT_STRUCT_DEFINE_PROXY_TYPE(                            \

include/boost/fusion/algorithm/iteration/detail/segmented_fold.hpp

@@ -14,6 +14,10 @@
 
 namespace boost { namespace fusion { namespace detail
 {
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
     template <typename Fun>
     struct segmented_fold_fun
     {
@@ -37,6 +41,9 @@ namespace boost { namespace fusion { namespace detail
             }
         };
     };
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
 
     // The default implementation of this lives in detail/fold.hpp
     template <typename Sequence, typename State, typename Fun, bool IsSequence, bool IsSegmented>

include/boost/fusion/algorithm/iteration/detail/segmented_for_each.hpp

@@ -13,6 +13,11 @@
 #include <boost/fusion/algorithm/iteration/for_each_fwd.hpp>
 #include <boost/fusion/support/segmented_fold_until.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion { namespace detail
 {
     template <typename Fun>
@@ -49,4 +54,8 @@ namespace boost { namespace fusion { namespace detail
     }
 }}}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif

include/boost/fusion/algorithm/transformation/pop_back.hpp

@@ -18,6 +18,11 @@
 #include <boost/mpl/int.hpp>
 #include <boost/mpl/if.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     template <typename Iterator_, bool IsLast>
@@ -168,5 +173,9 @@ namespace boost { namespace fusion
     }
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif
 

include/boost/fusion/container/deque/deque_iterator.hpp

@@ -20,6 +20,11 @@
 #include <boost/type_traits/add_const.hpp>
 #include <boost/type_traits/add_reference.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion {
 
     struct bidirectional_traversal_tag;
@@ -110,13 +115,14 @@ namespace boost { namespace fusion {
         {};
 
         Seq& seq_;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(deque_iterator& operator= (deque_iterator const&))
     };
 
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/container/list/cons_iterator.hpp

@@ -26,6 +26,10 @@ namespace boost { namespace fusion
     template <typename Cons>
     struct cons_iterator_identity;
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
     template <typename Cons = nil_>
     struct cons_iterator : iterator_base<cons_iterator<Cons> >
     {
@@ -41,10 +45,10 @@ namespace boost { namespace fusion
             : cons(in_cons) {}
 
         cons_type& cons;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(cons_iterator& operator= (cons_iterator const&))
     };
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
 
     struct nil_iterator : iterator_base<nil_iterator>
     {

include/boost/fusion/container/map/map_iterator.hpp

@@ -17,6 +17,11 @@
 #include <boost/type_traits/is_const.hpp>
 #include <boost/type_traits/add_const.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct random_access_traversal_tag;
@@ -155,13 +160,13 @@ namespace boost { namespace fusion
         {};
 
         Seq& seq_;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(map_iterator& operator= (map_iterator const&))
     };
-
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/container/vector/vector.hpp

@@ -220,21 +220,12 @@ namespace boost { namespace fusion
             void
             assign_sequence(Sequence&& seq)
             {
-                assign(std::forward<Sequence>(seq), detail::index_sequence<I...>());
-            }
-
-            template <typename Sequence>
-            BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED
-            void
-            assign(Sequence&&, detail::index_sequence<>) {}
-
-            template <typename Sequence, std::size_t N, std::size_t ...M>
-            BOOST_CXX14_CONSTEXPR BOOST_FUSION_GPU_ENABLED
-            void
-            assign(Sequence&& seq, detail::index_sequence<N, M...>)
-            {
-                at_impl(mpl::int_<N>()) = vector_detail::forward_at_c<N>(seq);
-                assign(std::forward<Sequence>(seq), detail::index_sequence<M...>());
+#ifndef BOOST_NO_CXX17_FOLD_EXPRESSIONS
+                (void(store<I, T>::elem = vector_detail::forward_at_c<I>(static_cast<Sequence&&>(seq))), ...);
+#else
+                int nofold[] = { (void(store<I, T>::elem = vector_detail::forward_at_c<I>(static_cast<Sequence&&>(seq))), 0)..., 0 };
+                (void)nofold;
+#endif
             }
 
         private:

include/boost/fusion/container/vector/vector_iterator.hpp

@@ -19,6 +19,11 @@
 #include <boost/type_traits/add_const.hpp>
 #include <boost/mpl/int.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct vector_iterator_tag;
@@ -41,17 +46,14 @@ namespace boost { namespace fusion
         vector_iterator(Vector& in_vec)
             : vec(in_vec) {}
 
-        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
-        vector_iterator(vector_iterator const& rhs)
-            : vec(rhs.vec) {}
-
         Vector& vec;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(vector_iterator& operator= (vector_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/include/adapt_assoc_adt.hpp

@@ -6,7 +6,7 @@
 ==============================================================================*/
 
 #ifndef BOOST_FUSION_INCLUDE_ADAPT_ASSOC_ADT_HPP
-#define BOOST_FUSION_INCLUDE_ADAPT_ASSOC_ADR_HPP
+#define BOOST_FUSION_INCLUDE_ADAPT_ASSOC_ADT_HPP
 
 #include <boost/fusion/support/config.hpp>
 #include <boost/fusion/adapted/adt/adapt_assoc_adt.hpp>

include/boost/fusion/include/identity_view.hpp

@@ -0,0 +1,12 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+    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)
+==============================================================================*/
+#if !defined(FUSION_INCLUDE_IDENTITY_VIEW)
+#define FUSION_INCLUDE_IDENTITY_VIEW
+
+#include <boost/fusion/support/config.hpp>
+#include <boost/fusion/view/identity_view.hpp>
+
+#endif

include/boost/fusion/iterator/detail/segment_sequence.hpp

@@ -13,6 +13,11 @@
 #include <boost/fusion/support/tag_of.hpp>
 #include <boost/fusion/sequence/intrinsic_fwd.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion { namespace detail
 {
     struct segment_sequence_tag {};
@@ -36,6 +41,10 @@ namespace boost { namespace fusion { namespace detail
     };
 }
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 namespace extension
 {
     template<typename Tag>

include/boost/fusion/iterator/iterator_adapter.hpp

@@ -19,6 +19,11 @@
 #include <boost/fusion/iterator/value_of.hpp>
 #include <boost/type_traits/remove_const.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     template <typename Derived_, typename Iterator_,
@@ -135,6 +140,10 @@ namespace boost { namespace fusion
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/sequence/io/detail/in.hpp

@@ -10,7 +10,6 @@
 #define FUSION_IN_05052005_0121
 
 #include <boost/fusion/support/config.hpp>
-#include <istream>
 #include <boost/fusion/sequence/io/detail/manip.hpp>
 
 #include <boost/mpl/bool.hpp>

include/boost/fusion/sequence/io/detail/manip.hpp

@@ -36,10 +36,10 @@ namespace boost { namespace fusion
     namespace detail
     {
         template <typename Tag>
-        int get_xalloc_index(Tag* = 0)
+        int get_xalloc_index(int xalloc())
         {
             // each Tag will have a unique index
-            static int index = std::ios::xalloc();
+            static int const index = xalloc();
             return index;
         }
 
@@ -66,15 +66,19 @@ namespace boost { namespace fusion
             {
                 static arena ar; // our arena
                 ar.data.push_back(new T(data));
-                stream.pword(get_xalloc_index<Tag>()) = ar.data.back();
+                stream.pword(get_xalloc_index<Tag>(stream.xalloc)) = ar.data.back();
             }
 
             static T const* get(Stream& stream)
             {
-                return (T const*)stream.pword(get_xalloc_index<Tag>());
+                return (T const*)stream.pword(get_xalloc_index<Tag>(stream.xalloc));
             }
         };
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
         template <typename Tag, typename Stream>
         class string_ios_manip
         {
@@ -110,7 +114,6 @@ namespace boost { namespace fusion
             {
                 // read a delimiter
                 string_type const* p = stream_data_t::get(stream);
-                std::ws(stream);
 
                 if (p)
                 {
@@ -137,16 +140,16 @@ namespace boost { namespace fusion
                     if (stream.get() != c)
                     {
                         stream.unget();
-                        stream.setstate(std::ios::failbit);
+                        stream.setstate(Stream::failbit);
                     }
                 }
             }
 
             Stream& stream;
-
-            // silence MSVC warning C4512: assignment operator could not be generated
-            BOOST_DELETED_FUNCTION(string_ios_manip& operator= (string_ios_manip const&))
         };
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
 
     } // detail
 

include/boost/fusion/sequence/io/detail/out.hpp

@@ -10,7 +10,6 @@
 #define FUSION_OUT_05052005_0121
 
 #include <boost/fusion/support/config.hpp>
-#include <ostream>
 #include <boost/fusion/sequence/io/detail/manip.hpp>
 
 #include <boost/mpl/bool.hpp>

include/boost/fusion/sequence/io/in.hpp

@@ -10,9 +10,9 @@
 #define BOOST_IN_05042005_0120
 
 #include <boost/fusion/support/config.hpp>
-#include <istream>
 #include <boost/fusion/sequence/io/detail/in.hpp>
 #include <boost/fusion/support/is_sequence.hpp>
+#include <iosfwd>
 
 namespace boost { namespace fusion
 {

include/boost/fusion/sequence/io/out.hpp

@@ -10,11 +10,11 @@
 #define BOOST_OUT_05042005_0120
 
 #include <boost/fusion/support/config.hpp>
-#include <ostream>
 #include <boost/fusion/sequence/io/detail/out.hpp>
 #include <boost/fusion/support/is_sequence.hpp>
 #include <boost/utility/enable_if.hpp>
 #include <boost/mpl/or.hpp>
+#include <iosfwd>
 
 namespace boost { namespace fusion
 {

include/boost/fusion/support/config.hpp

@@ -127,4 +127,14 @@ namespace boost { namespace fusion { namespace detail
 #   define BOOST_FUSION_NOEXCEPT_ON_DEFAULTED BOOST_NOEXCEPT
 #endif
 
+#ifdef _MSC_VER
+#   define BOOST_FUSION_PUSH_WARNINGS __pragma(warning(push))
+#   define BOOST_FUSION_POP_WARNINGS  __pragma(warning(pop))
+#   define BOOST_FUSION_DISABLE_MSVC_WARNING(num) __pragma(warning(disable : num))
+#else
+#   define BOOST_FUSION_PUSH_WARNINGS
+#   define BOOST_FUSION_POP_WARNINGS
+#   define BOOST_FUSION_DISABLE_MSVC_WARNING(num)
+#endif
+
 #endif

include/boost/fusion/support/deduce.hpp

@@ -10,7 +10,7 @@
 #define BOOST_FUSION_SUPPORT_DEDUCE_HPP_INCLUDED
 
 #include <boost/fusion/support/config.hpp>
-#include <boost/ref.hpp>
+#include <boost/core/ref.hpp>
 
 #ifndef BOOST_NO_CXX11_HDR_FUNCTIONAL
 #include <functional>

include/boost/fusion/support/detail/as_fusion_element.hpp

@@ -9,7 +9,7 @@
 #define FUSION_AS_FUSION_ELEMENT_05052005_0338
 
 #include <boost/fusion/support/config.hpp>
-#include <boost/ref.hpp>
+#include <boost/core/ref.hpp>
 
 #ifndef BOOST_NO_CXX11_HDR_FUNCTIONAL
 #include <functional>

include/boost/fusion/support/pair.hpp

@@ -120,6 +120,17 @@ namespace boost { namespace fusion
         return pair<First, typename detail::as_fusion_element<Second>::type>(val);
     }
 
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+    template <typename First, typename Second>
+    BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
+    inline typename result_of::make_pair<First,Second>::type
+    make_pair(Second&& val)
+    {
+        return pair<First, typename detail::as_fusion_element<Second>::type>(
+            BOOST_FUSION_FWD_ELEM(Second, val));
+    }
+#endif
+
     template <typename First, typename Second>
     inline std::ostream&
     operator<<(std::ostream& os, pair<First, Second> const& p)

include/boost/fusion/support/tag_of.hpp

@@ -48,11 +48,17 @@ namespace boost { namespace fusion
     {
         BOOST_MPL_HAS_XXX_TRAIT_DEF(fusion_tag)
 
+        template<typename Sequence, typename Active=void>
+        struct tag_of_fallback
+        {
+            typedef non_fusion_tag type;
+        };
+
         template <typename Sequence, typename Active>
         struct tag_of_impl
           : mpl::if_<fusion::detail::is_mpl_sequence<Sequence>,
               mpl::identity<mpl_sequence_tag>,
-              mpl::identity<non_fusion_tag> >::type
+              mpl::identity<typename tag_of_fallback<Sequence>::type> >::type
         {};
 
         template <typename Sequence>

include/boost/fusion/view.hpp

@@ -17,5 +17,6 @@
 #include <boost/fusion/view/transform_view.hpp>
 #include <boost/fusion/view/zip_view.hpp>
 #include <boost/fusion/view/flatten_view.hpp>
+#include <boost/fusion/view/identity_view.hpp>
 
 #endif

include/boost/fusion/view/filter_view/filter_view.hpp

@@ -22,6 +22,11 @@
 #include <boost/mpl/inherit.hpp>
 #include <boost/mpl/identity.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct filter_view_tag;
@@ -51,22 +56,18 @@ namespace boost { namespace fusion
             : seq(in_seq)
         {}
 
-        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
-        filter_view(filter_view const& rhs)
-            : seq(rhs.seq)
-        {}
-
         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         first_type first() const { return fusion::begin(seq); }
         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         last_type last() const { return fusion::end(seq); }
         typename mpl::if_<traits::is_view<Sequence>, Sequence, Sequence&>::type seq;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(filter_view& operator= (filter_view const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif
 
 

include/boost/fusion/view/filter_view/filter_view_iterator.hpp

@@ -26,6 +26,11 @@
 #include <boost/fusion/view/filter_view/detail/value_of_data_impl.hpp>
 #include <boost/fusion/view/filter_view/detail/key_of_impl.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct filter_view_iterator_tag;
@@ -59,17 +64,14 @@ namespace boost { namespace fusion
         filter_iterator(First const& in_first)
             : first(filter::iter_call(first_converter::call(in_first))) {}
 
-        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
-        filter_iterator(filter_iterator const& rhs)
-            : first(rhs.first) {}
-
         first_type first;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(filter_iterator& operator= (filter_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/view/flatten_view/flatten_view.hpp

@@ -19,6 +19,10 @@
 #include <boost/fusion/sequence/intrinsic/end.hpp>
 #include <boost/fusion/view/flatten_view/flatten_view_iterator.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
 
 namespace boost { namespace fusion
 {
@@ -52,6 +56,10 @@ namespace boost { namespace fusion
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 namespace boost { namespace fusion { namespace extension
 {
     template<>

include/boost/fusion/view/flatten_view/flatten_view_iterator.hpp

@@ -19,6 +19,10 @@
 #include <boost/fusion/iterator/deref.hpp>
 #include <boost/fusion/iterator/value_of.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
 
 namespace boost { namespace fusion
 {
@@ -46,6 +50,10 @@ namespace boost { namespace fusion
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 namespace boost { namespace fusion { namespace detail
 {
     template<class Iterator, class = void>

include/boost/fusion/view/identity_view.hpp

@@ -0,0 +1,14 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+    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)
+==============================================================================*/
+
+#if !defined(BOOST_FUSION_SEQUENCE_IDENTITY_VIEW_HPP_INCLUDED)
+#define BOOST_FUSION_SEQUENCE_IDENTITY_VIEW_HPP_INCLUDED
+
+#include <boost/fusion/support/config.hpp>
+#include <boost/fusion/view/identity_view/identity_view.hpp>
+
+
+#endif

include/boost/fusion/view/identity_view/identity_view.hpp

@@ -0,0 +1,50 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+    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)
+==============================================================================*/
+
+#if !defined(BOOST_FUSION_IDENTITY_VIEW_HPP_INCLUDED)
+#define BOOST_FUSION_IDENTITY_VIEW_HPP_INCLUDED
+
+#include <boost/fusion/support/config.hpp>
+#include <boost/fusion/view/transform_view.hpp>
+#include <boost/functional/identity.hpp>
+#include <boost/utility/result_of.hpp>
+
+namespace boost { namespace fusion {
+    namespace detail {
+        struct identity : boost::identity
+        {
+        };
+    }
+}}
+
+namespace boost {
+    template<typename T>
+    struct result_of<fusion::detail::identity(T)>
+    {
+        typedef T type;
+    };
+}
+
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+namespace boost { namespace fusion {
+    template<typename Sequence> struct identity_view 
+        : transform_view<Sequence, detail::identity>
+    {
+        typedef transform_view<Sequence, detail::identity> base_type;
+
+        BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
+        identity_view(Sequence& in_seq)
+            : base_type(in_seq, detail::identity()) {}
+    };
+}}
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
+#endif 

include/boost/fusion/view/joint_view/joint_view.hpp

@@ -25,6 +25,11 @@
 #include <boost/mpl/inherit.hpp>
 #include <boost/mpl/identity.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct joint_view_tag;
@@ -69,15 +74,16 @@ namespace boost { namespace fusion
         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         concat_last_type concat_last() const { return fusion::end(seq2); }
 
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(joint_view& operator= (joint_view const&))
-
     private:
         typename mpl::if_<traits::is_view<Sequence1>, Sequence1, Sequence1&>::type seq1;
         typename mpl::if_<traits::is_view<Sequence2>, Sequence2, Sequence2&>::type seq2;
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif
 
 

include/boost/fusion/view/joint_view/joint_view_iterator.hpp

@@ -20,6 +20,11 @@
 #include <boost/fusion/view/joint_view/detail/key_of_impl.hpp>
 #include <boost/static_assert.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct joint_view_iterator_tag;
@@ -49,12 +54,13 @@ namespace boost { namespace fusion
 
         first_type first;
         concat_type concat;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(joint_view_iterator& operator= (joint_view_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/view/nview/nview_iterator.hpp

@@ -26,6 +26,11 @@
 #include <boost/fusion/view/nview/detail/distance_impl.hpp>
 #include <boost/fusion/view/nview/detail/equal_to_impl.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct nview_iterator_tag;
@@ -46,13 +51,14 @@ namespace boost { namespace fusion
           : seq(in_seq) {}
 
         Sequence& seq;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(nview_iterator& operator= (nview_iterator const&))
     };
 
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/view/repetitive_view/repetitive_view.hpp

@@ -18,6 +18,10 @@
 #include <boost/fusion/view/repetitive_view/detail/begin_impl.hpp>
 #include <boost/fusion/view/repetitive_view/detail/end_impl.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
 
 namespace boost { namespace fusion
 {
@@ -43,11 +47,12 @@ namespace boost { namespace fusion
             : seq(in_seq) {}
 
         stored_seq_type seq;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(repetitive_view& operator= (repetitive_view const&))
     };
 
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif

include/boost/fusion/view/repetitive_view/repetitive_view_iterator.hpp

@@ -19,6 +19,11 @@
 #include <boost/fusion/view/repetitive_view/detail/next_impl.hpp>
 #include <boost/fusion/view/repetitive_view/detail/value_of_impl.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct repetitive_view_iterator_tag;
@@ -46,12 +51,13 @@ namespace boost { namespace fusion
 
         Sequence& seq;
         pos_type pos;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(repetitive_view_iterator& operator= (repetitive_view_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/view/reverse_view/detail/deref_data_impl.hpp

@@ -1,5 +1,6 @@
 /*=============================================================================
     Copyright (c) 2009 Christopher Schmidt
+    Copyright (c) 2021-2022 Denis Mikhailov
 
     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)
@@ -10,6 +11,7 @@
 
 #include <boost/fusion/support/config.hpp>
 #include <boost/fusion/iterator/deref_data.hpp>
+#include <boost/fusion/iterator/prior.hpp>
 
 namespace boost { namespace fusion { namespace extension
 {
@@ -23,14 +25,18 @@ namespace boost { namespace fusion { namespace extension
         struct apply
         {
             typedef typename
-                result_of::deref_data<typename It::first_type>::type
+                result_of::deref_data<
+                    typename result_of::prior<
+                        typename It::first_type
+                    >::type
+                >::type
             type;
 
             BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
             static type
             call(It const& it)
             {
-                return fusion::deref_data(it.first);
+                return fusion::deref_data(fusion::prior(it.first));
             }
         };
     };

include/boost/fusion/view/reverse_view/detail/key_of_impl.hpp

@@ -1,5 +1,6 @@
 /*=============================================================================
     Copyright (c) 2009 Christopher Schmidt
+    Copyright (c) 2021-2022 Denis Mikhailov
 
     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)
@@ -10,6 +11,7 @@
 
 #include <boost/fusion/support/config.hpp>
 #include <boost/fusion/iterator/key_of.hpp>
+#include <boost/fusion/iterator/prior.hpp>
 
 namespace boost { namespace fusion { namespace extension
 {
@@ -21,8 +23,15 @@ namespace boost { namespace fusion { namespace extension
     {
         template <typename It>
         struct apply
-          : result_of::key_of<typename It::it_type>
-        {};
+        {
+            typedef typename
+                result_of::key_of<
+                    typename result_of::prior<
+                        typename It::first_type
+                    >::type
+                >::type
+            type;
+        };
     };
 }}}
 

include/boost/fusion/view/reverse_view/detail/value_of_data_impl.hpp

@@ -1,5 +1,6 @@
 /*=============================================================================
     Copyright (c) 2009 Christopher Schmidt
+    Copyright (c) 2021-2022 Denis Mikhailov
 
     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)
@@ -10,6 +11,7 @@
 
 #include <boost/fusion/support/config.hpp>
 #include <boost/fusion/iterator/value_of_data.hpp>
+#include <boost/fusion/iterator/prior.hpp>
 
 namespace boost { namespace fusion { namespace extension
 {
@@ -21,8 +23,15 @@ namespace boost { namespace fusion { namespace extension
     {
         template <typename It>
         struct apply
-          : result_of::value_of_data<typename It::first_type>
-        {};
+        {
+            typedef typename
+                result_of::value_of_data<
+                    typename result_of::prior<
+                        typename It::first_type
+                    >::type
+                >::type
+            type;
+        };
     };
 }}}
 

include/boost/fusion/view/reverse_view/reverse_view.hpp

@@ -27,6 +27,11 @@
 #include <boost/mpl/inherit.hpp>
 #include <boost/mpl/identity.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct reverse_view_tag;
@@ -60,12 +65,13 @@ namespace boost { namespace fusion
         BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
         last_type last() const { return fusion::end(seq); }
         typename mpl::if_<traits::is_view<Sequence>, Sequence, Sequence&>::type seq;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(reverse_view& operator= (reverse_view const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif
 
 

include/boost/fusion/view/reverse_view/reverse_view_iterator.hpp

@@ -24,6 +24,11 @@
 #include <boost/type_traits/is_base_of.hpp>
 #include <boost/static_assert.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct reverse_view_iterator_tag;
@@ -47,12 +52,13 @@ namespace boost { namespace fusion
             : first(converter::call(in_first)) {}
 
         first_type first;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(reverse_view_iterator& operator= (reverse_view_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/view/single_view/single_view_iterator.hpp

@@ -20,6 +20,11 @@
 #include <boost/fusion/view/single_view/detail/value_of_impl.hpp>
 #include <boost/config.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct single_view_iterator_tag;
@@ -40,11 +45,13 @@ namespace boost { namespace fusion
             : view(in_view) {}
 
         SingleView& view;
-
-        BOOST_DELETED_FUNCTION(single_view_iterator& operator=(single_view_iterator const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

include/boost/fusion/view/transform_view/detail/deref_data_impl.hpp

@@ -0,0 +1,73 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+    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)
+==============================================================================*/
+
+#if !defined(BOOST_FUSION_TRANSFORM_VIEW_DEREF_DATA_IMPL_JAN_9_2022_0354PM)
+#define BOOST_FUSION_TRANSFORM_VIEW_DEREF_DATA_IMPL_JAN_9_2022_0354PM
+
+#include <boost/fusion/support/config.hpp>
+#include <boost/fusion/iterator/deref.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/type_traits/add_reference.hpp>
+#include <boost/type_traits/add_const.hpp>
+#include <boost/type_traits/is_reference.hpp>
+#include <boost/type_traits/is_const.hpp>
+#include <boost/utility/result_of.hpp>
+#include <boost/mpl/if.hpp>
+
+namespace boost { namespace fusion
+{
+    struct transform_view_iterator_tag;
+    struct transform_view_iterator2_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct deref_data_impl;
+
+        // Unary Version
+        template<>
+        struct deref_data_impl<transform_view_iterator_tag>
+        {
+            template <typename Iterator>
+            struct apply
+            {
+                typedef typename
+                    result_of::deref<typename Iterator::first_type>::type
+                value_type;
+
+                typedef typename Iterator::transform_type F;
+                typedef typename boost::result_of<F(value_type)>::type transformed_type;
+                typedef typename boost::remove_reference<transformed_type>::type transformed_type_unref;
+                typedef typename boost::remove_const<transformed_type_unref>::type transformed_type_unconst;
+
+                typedef typename transformed_type_unconst::second_type raw_type;
+                typedef typename
+                    boost::mpl::if_<
+                        is_reference<transformed_type>
+                      , typename boost::mpl::if_<
+                            is_const<transformed_type_unref>
+                            , typename boost::add_reference<typename boost::add_const<raw_type>::type>::type
+                            , typename boost::add_reference<raw_type>::type
+                        >::type
+                      , raw_type
+                    >::type
+                type;
+
+                BOOST_CONSTEXPR BOOST_FUSION_GPU_ENABLED
+                static type
+                call(Iterator const& i)
+                {
+                    return i.f(fusion::deref(i.first)).second;
+                }
+            };
+        };
+
+        // Binary Version is not supported with Associative Sequence
+    }
+}}
+
+#endif

include/boost/fusion/view/transform_view/detail/key_of_impl.hpp

@@ -0,0 +1,49 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+    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)
+==============================================================================*/
+
+#if !defined(BOOST_FUSION_TRANSFORM_VIEW_KEY_OF_IMPL_JAN_9_2022_0354PM)
+#define BOOST_FUSION_TRANSFORM_VIEW_KEY_OF_IMPL_JAN_9_2022_0354PM
+
+#include <boost/fusion/support/config.hpp>
+#include <boost/fusion/iterator/deref.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/utility/result_of.hpp>
+
+namespace boost { namespace fusion
+{
+    struct transform_view_iterator_tag;
+    struct transform_view_iterator2_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct key_of_impl;
+
+        // Unary Version
+        template<>
+        struct key_of_impl<transform_view_iterator_tag>
+        {
+            template <typename Iterator>
+            struct apply
+            {
+                typedef typename
+                    result_of::deref<typename Iterator::first_type>::type
+                value_type;
+
+                typedef typename Iterator::transform_type F;
+                typedef typename boost::result_of<F(value_type)>::type transformed_type;
+                typedef typename boost::remove_reference<transformed_type>::type transformed_type_unref;
+                typedef typename boost::remove_const<transformed_type_unref>::type transformed_type_unconst;
+
+                typedef typename transformed_type_unconst::first_type type;
+            };
+        };
+
+        // Binary Version is not supported with Associative Sequence
+    }
+}}
+#endif

include/boost/fusion/view/transform_view/detail/value_of_data_impl.hpp

@@ -0,0 +1,49 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+    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)
+==============================================================================*/
+
+#if !defined(BOOST_FUSION_TRANSFORM_VIEW_VALUE_OF_IMPL_JAN_9_2022_0354PM)
+#define BOOST_FUSION_TRANSFORM_VIEW_VALUE_OF_IMPL_JAN_9_2022_0354PM
+
+#include <boost/fusion/support/config.hpp>
+#include <boost/fusion/iterator/deref.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+#include <boost/type_traits/remove_const.hpp>
+#include <boost/utility/result_of.hpp>
+
+namespace boost { namespace fusion
+{
+    struct transform_view_iterator_tag;
+    struct transform_view_iterator2_tag;
+
+    namespace extension
+    {
+        template<typename Tag>
+        struct value_of_data_impl;
+
+        // Unary Version
+        template<>
+        struct value_of_data_impl<transform_view_iterator_tag>
+        {
+            template <typename Iterator>
+            struct apply
+            {
+                typedef typename
+                    result_of::deref<typename Iterator::first_type>::type
+                value_type;
+
+                typedef typename Iterator::transform_type F;
+                typedef typename boost::result_of<F(value_type)>::type transformed_type;
+                typedef typename boost::remove_reference<transformed_type>::type transformed_type_unref;
+                typedef typename boost::remove_const<transformed_type_unref>::type transformed_type_unconst;
+
+                typedef typename transformed_type_unconst::second_type type;
+            };
+        };
+
+        // Binary Version is not supported with Associative Sequence
+    }
+}}
+#endif

include/boost/fusion/view/transform_view/transform_view.hpp

@@ -27,6 +27,11 @@
 #include <boost/fusion/sequence/intrinsic/size.hpp>
 #include <boost/mpl/bool.hpp>
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
+
 namespace boost { namespace fusion
 {
     struct void_;
@@ -75,9 +80,6 @@ namespace boost { namespace fusion
         transform_type f;
         typename mpl::if_<traits::is_view<Sequence1>, Sequence1, Sequence1&>::type seq1;
         typename mpl::if_<traits::is_view<Sequence2>, Sequence2, Sequence2&>::type seq2;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(transform_view& operator= (transform_view const&))
     };
 
     // Unary Version
@@ -111,12 +113,13 @@ namespace boost { namespace fusion
         last_type last() const { return fusion::end(seq); }
         typename mpl::if_<traits::is_view<Sequence>, Sequence, Sequence&>::type seq;
         transform_type f;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(transform_view& operator= (transform_view const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #endif
 
 

include/boost/fusion/view/transform_view/transform_view_iterator.hpp

@@ -19,6 +19,14 @@
 #include <boost/fusion/view/transform_view/detail/advance_impl.hpp>
 #include <boost/fusion/view/transform_view/detail/distance_impl.hpp>
 #include <boost/fusion/view/transform_view/detail/equal_to_impl.hpp>
+#include <boost/fusion/view/transform_view/detail/key_of_impl.hpp>
+#include <boost/fusion/view/transform_view/detail/value_of_data_impl.hpp>
+#include <boost/fusion/view/transform_view/detail/deref_data_impl.hpp>
+
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
 
 namespace boost { namespace fusion
 {
@@ -41,9 +49,6 @@ namespace boost { namespace fusion
 
         first_type first;
         transform_type f;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(transform_view_iterator& operator= (transform_view_iterator const&))
     };
 
     // Binary Version
@@ -68,12 +73,13 @@ namespace boost { namespace fusion
         first1_type first1;
         first2_type first2;
         transform_type f;
-
-        // silence MSVC warning C4512: assignment operator could not be generated
-        BOOST_DELETED_FUNCTION(transform_view_iterator2& operator= (transform_view_iterator2 const&))
     };
 }}
 
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
+
 #ifdef BOOST_FUSION_WORKAROUND_FOR_LWG_2408
 namespace std
 {

test/Jamfile

@@ -156,6 +156,7 @@ project
         : <define>BOOST_FUSION_DISABLE_VARIADIC_VECTOR
         : tuple_traits__no_variadic ]
     [ run sequence/transform_view.cpp ]
+    [ run sequence/identity_view.cpp ]
     [ run sequence/vector_comparison.cpp ]
     [ run sequence/vector_construction.cpp ]
     [ run sequence/vector_conversion.cpp ]
@@ -270,6 +271,11 @@ project
         : [ requires cxx11_variadic_templates ] ]
     [ compile support/tag_of.cpp ]
     [ compile support/unused.cpp ]
+    [ compile support/detail/tag_of_fallback.cpp ]
+
+    [ compile-fail support/make_pair_r-value.cpp ]
+    [ compile support/make_pair_r-value.cpp
+        : [ requires cxx11_rvalue_references ] ]
 
 #   [ compile-fail xxx.cpp  ]
 

test/functional/fused.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/adapter/fused.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 
 #include <boost/fusion/container/generation/make_vector.hpp>
 #include <boost/fusion/container/vector.hpp>

test/functional/fused_function_object.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/adapter/fused_function_object.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 #include <boost/mpl/empty_base.hpp>
 
 #include <boost/fusion/container/generation/make_vector.hpp>

test/functional/fused_procedure.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/adapter/fused_procedure.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 #include <boost/mpl/empty_base.hpp>
 
 #include <boost/fusion/container/generation/make_vector.hpp>

test/functional/invoke.cpp

@@ -16,7 +16,7 @@
 #endif
 
 #include <memory>
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 
 #include <boost/type_traits/is_same.hpp>
 

test/functional/invoke_function_object.cpp

@@ -17,7 +17,7 @@
 #include <boost/type_traits/is_same.hpp>
 
 #include <memory>
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 
 #include <boost/mpl/int.hpp>
 

test/functional/invoke_procedure.cpp

@@ -16,7 +16,7 @@
 #endif
 
 #include <memory>
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 
 #include <boost/mpl/int.hpp>
 

test/functional/make_fused.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/generation/make_fused.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 #include <boost/mpl/empty_base.hpp>
 
 #include <boost/fusion/container/generation/make_vector.hpp>

test/functional/make_fused_function_object.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/generation/make_fused_function_object.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 #include <boost/mpl/empty_base.hpp>
 
 #include <boost/fusion/container/generation/make_vector.hpp>

test/functional/make_fused_procedure.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/generation/make_fused_procedure.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 #include <boost/mpl/empty_base.hpp>
 
 #include <boost/fusion/container/generation/make_vector.hpp>

test/functional/make_unfused.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/generation/make_unfused.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 
 #include <boost/mpl/empty_base.hpp>
 #include <boost/mpl/if.hpp>
@@ -19,11 +19,11 @@
 
 #include <boost/utility/result_of.hpp>
 #include <boost/core/enable_if.hpp>
+#include <boost/core/ref.hpp>
 
 #include <boost/fusion/sequence/intrinsic/empty.hpp>
 #include <boost/fusion/algorithm/iteration/fold.hpp>
 
-#include <boost/ref.hpp>
 
 namespace fusion = boost::fusion;
 namespace mpl = boost::mpl;

test/functional/unfused.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/adapter/unfused.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 
 #include <boost/mpl/empty_base.hpp>
 #include <boost/mpl/identity.hpp>

test/functional/unfused_typed.cpp

@@ -9,7 +9,7 @@
 #include <boost/fusion/functional/adapter/unfused_typed.hpp>
 #include <boost/detail/lightweight_test.hpp>
 
-#include <boost/noncopyable.hpp>
+#include <boost/core/noncopyable.hpp>
 
 #include <boost/mpl/empty_base.hpp>
 #include <boost/mpl/identity.hpp>

test/sequence/deduce_sequence.cpp

@@ -13,7 +13,7 @@
 
 #include <boost/mpl/equal.hpp>
 
-#include <boost/ref.hpp>
+#include <boost/core/ref.hpp>
 #ifndef BOOST_NO_CXX11_HDR_FUNCTIONAL
 #include <functional>
 #endif

test/sequence/identity_view.cpp

@@ -0,0 +1,193 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+
+    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 <boost/detail/lightweight_test.hpp>
+#include <boost/fusion/container/vector/vector.hpp>
+#include <boost/fusion/container/map/map.hpp>
+#include <boost/fusion/container/generation/make_map.hpp>
+#include <boost/fusion/algorithm/auxiliary/copy.hpp>
+#include <boost/fusion/adapted/mpl.hpp>
+#include <boost/fusion/sequence/io/out.hpp>
+#include <boost/fusion/container/generation/make_vector.hpp>
+#include <boost/fusion/sequence/comparison/equal_to.hpp>
+#include <boost/fusion/view/identity_view/identity_view.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
+#include <boost/fusion/sequence/intrinsic/at.hpp>
+#include <boost/fusion/sequence/intrinsic/value_at.hpp>
+#include <boost/fusion/sequence/intrinsic/at_key.hpp>
+#include <boost/fusion/sequence/intrinsic/value_at_key.hpp>
+#include <boost/fusion/sequence/intrinsic/has_key.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
+#include <boost/fusion/iterator/next.hpp>
+#include <boost/fusion/iterator/prior.hpp>
+#include <boost/fusion/iterator/advance.hpp>
+#include <boost/fusion/iterator/deref.hpp>
+#include <boost/fusion/iterator/distance.hpp>
+#include <boost/fusion/iterator/key_of.hpp>
+#include <boost/fusion/iterator/deref_data.hpp>
+#include <boost/fusion/iterator/value_of_data.hpp>
+#include <boost/fusion/support/pair.hpp>
+#include <boost/fusion/support/category_of.hpp>
+
+#include <boost/mpl/range_c.hpp>
+#include <boost/mpl/assert.hpp>
+#include <boost/mpl/at.hpp>
+#include <boost/mpl/map.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/static_assert.hpp>
+#include <boost/typeof/typeof.hpp>
+#include <boost/type_traits/remove_reference.hpp>
+
+struct abstract
+{
+    virtual void foo() = 0;
+};
+
+int
+main()
+{
+    using namespace boost::fusion;
+
+    std::cout << tuple_open('[');
+    std::cout << tuple_close(']');
+    std::cout << tuple_delimiter(", ");
+
+/// Testing the identity_view
+
+    {
+        typedef boost::mpl::range_c<int, 5, 9> sequence_type;
+        sequence_type sequence;
+        typedef identity_view<sequence_type> xform_type;
+        xform_type xform(sequence);
+
+        std::cout << xform << std::endl;
+        BOOST_TEST((xform == make_vector(5, 6, 7, 8))); 
+
+        typedef boost::fusion::result_of::begin<xform_type>::type first_type;
+        first_type first_it(boost::fusion::begin(xform));
+
+        typedef boost::fusion::result_of::next<first_type>::type next_type;
+        next_type next_it(boost::fusion::next(first_it));
+        BOOST_TEST((*next_it == 6));
+        BOOST_TEST((*boost::fusion::prior(next_it) == 5));
+        BOOST_TEST((boost::fusion::distance(first_it, next_it) == 1));
+
+        BOOST_TEST((*boost::fusion::advance_c<3>(boost::fusion::begin(xform)) == 8));
+        BOOST_TEST((boost::fusion::at_c<2>(xform) == 7));
+        BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_at_c<xform_type, 0>::type,  boost::mpl::integral_c<int, 5> >));
+    }
+    
+    {
+        typedef vector<int, int, int, int, int> sequence_type;
+        sequence_type seq;
+        identity_view<sequence_type> ident(seq);
+        copy(make_vector(1, 2, 3, 4, 5), ident);
+        std::cout << seq << std::endl;
+        BOOST_TEST((seq == make_vector(1, 2, 3, 4, 5)));
+    }
+    
+    /// Associative
+    {
+        typedef map<
+            pair<int, char>
+          , pair<double, std::string>
+          , pair<abstract, int> >
+        map_type;
+        typedef identity_view<map_type> transformed_type;
+
+        BOOST_MPL_ASSERT((traits::is_associative<transformed_type>));
+        BOOST_MPL_ASSERT((traits::is_random_access<transformed_type>));
+
+        map_type m(
+            make_pair<int>('X')
+          , make_pair<double>("Men")
+          , make_pair<abstract>(2));
+        transformed_type t(m);
+
+        std::cout << at_key<int>(t) << std::endl;
+        std::cout << at_key<double>(t) << std::endl;
+        std::cout << at_key<abstract>(t) << std::endl;
+
+        BOOST_TEST(at_key<int>(t) == 'X');
+        BOOST_TEST(at_key<double>(t) == "Men");
+        BOOST_TEST(at_key<abstract>(t) == 2);
+
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, int>::type, char>::value));
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, double>::type, std::string>::value));
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, abstract>::type, int>::value));
+
+        std::cout << t << std::endl;
+
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, int>::value));
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, double>::value));
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, abstract>::value));
+        BOOST_STATIC_ASSERT((!boost::fusion::result_of::has_key<transformed_type, std::string>::value));
+
+        std::cout << deref_data(begin(t)) << std::endl;
+        std::cout << deref_data(boost::fusion::next(begin(t))) << std::endl;
+
+        BOOST_TEST(deref_data(begin(t)) == 'X');
+        BOOST_TEST(deref_data(boost::fusion::next(begin(t))) == "Men");
+        BOOST_TEST(deref_data(boost::fusion::next(next(begin(t)))) == 2);
+
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::begin<transformed_type>::type>::type, int>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type, double>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::next<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type>::type, abstract>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::begin<transformed_type>::type>::type, char>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type, std::string>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::next<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type>::type, int>::value));
+
+        // Test random access interface.
+        pair<int, char> a = at_c<0>(t); (void) a;
+        pair<double, std::string> b = at_c<1>(t);
+        pair<abstract, int> c = at_c<2>(t);
+        (void)c;
+
+        typedef boost::fusion::result_of::begin<transformed_type>::type first;
+        typedef boost::fusion::result_of::next<first>::type second;
+        typedef boost::fusion::result_of::next<second>::type third;
+
+        BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<first>::type, boost::fusion::pair<int, char> >));
+        BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<second>::type, boost::fusion::pair<double, std::string> >));
+        BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<third>::type, boost::fusion::pair<abstract, int> >));
+    }
+
+    {
+        // compile test only
+        // make sure result_of::deref_data returns a reference
+        typedef map<pair<float, int> > map_type;
+        typedef identity_view<map_type> transformed_type;
+        typedef boost::fusion::result_of::begin<transformed_type>::type i_type;
+        typedef boost::fusion::result_of::deref_data<i_type>::type r_type;
+        BOOST_STATIC_ASSERT((boost::is_same<r_type, int&>::value));
+    }
+
+    {
+        // compile test only
+        // make sure result_of::deref_data is const correct
+        typedef map<pair<float, int> > const map_type;
+        typedef identity_view<map_type> transformed_type;
+        typedef boost::fusion::result_of::begin<transformed_type>::type i_type;
+        typedef boost::fusion::result_of::deref_data<i_type>::type r_type;
+        BOOST_STATIC_ASSERT((boost::is_same<r_type, int const&>::value));
+    }
+
+    {
+        // compile test only
+        // make sure result_of::deref_data will not const for non-constant references
+        typedef map<pair<float, int&> > const map_type;
+        typedef identity_view<map_type> transformed_type;
+        typedef boost::fusion::result_of::begin<transformed_type>::type i_type;
+        typedef boost::fusion::result_of::deref_data<i_type>::type r_type;
+        BOOST_STATIC_ASSERT((boost::is_same<r_type, int&>::value));
+    }
+
+    return boost::report_errors();
+}
+

test/sequence/reverse_view.cpp

@@ -1,5 +1,6 @@
 /*=============================================================================
     Copyright (c) 2001-2011 Joel de Guzman
+    Copyright (c) 2021-2022 Denis Mikhailov
 
     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)
@@ -15,6 +16,9 @@
 #include <boost/fusion/sequence/intrinsic/begin.hpp>
 #include <boost/fusion/sequence/intrinsic/at.hpp>
 #include <boost/fusion/sequence/intrinsic/value_at.hpp>
+#include <boost/fusion/sequence/intrinsic/has_key.hpp>
+#include <boost/fusion/sequence/intrinsic/at_key.hpp>
+#include <boost/fusion/sequence/intrinsic/value_at_key.hpp>
 #include <boost/fusion/iterator/next.hpp>
 #include <boost/fusion/iterator/prior.hpp>
 #include <boost/fusion/iterator/deref.hpp>
@@ -102,6 +106,21 @@ main()
         BOOST_TEST((at_c<2>(rev) == pair2("two")));
         BOOST_TEST((at_c<3>(rev) == pair1("one")));
         BOOST_TEST((at_c<4>(rev) == pair0("zero")));
+        BOOST_TEST(( has_key< boost::mpl::int_<0> >(rev) 
+                  && has_key< boost::mpl::int_<4> >(rev) 
+                 && !has_key< boost::mpl::int_<-1> >(rev) 
+                 && !has_key< boost::mpl::int_<5> >(rev) ));
+        BOOST_TEST((at_key< boost::mpl::int_<0> >(rev) == "zero"));
+        BOOST_TEST((at_key< boost::mpl::int_<1> >(rev) == "one"));
+        BOOST_TEST((at_key< boost::mpl::int_<2> >(rev) == "two"));
+        BOOST_TEST((at_key< boost::mpl::int_<3> >(rev) == "three"));
+        BOOST_TEST((at_key< boost::mpl::int_<4> >(rev) == "four"));
+        BOOST_TEST(( (at_key< boost::mpl::int_<0> >(rev) = "new_zero") == "new_zero"
+                   && at_key< boost::mpl::int_<0> >(rev) == "new_zero" ));
+        BOOST_MPL_ASSERT((boost::mpl::and_<result_of::has_key<view_type, boost::mpl::int_<0> >
+                        , boost::mpl::not_<result_of::has_key<view_type, boost::mpl::int_<-1> > > >));
+        BOOST_MPL_ASSERT((boost::is_same<result_of::at_key<view_type, boost::mpl::int_<0> >::type, std::string&>));
+        BOOST_MPL_ASSERT((boost::is_same<result_of::value_at_key<view_type, boost::mpl::int_<0> >::type, std::string>));
     }
 
     return boost::report_errors();

test/sequence/segmented_iterator_range.cpp

@@ -21,6 +21,10 @@
 #include <boost/static_assert.hpp>
 #include "tree.hpp"
 
+#ifdef _MSC_VER
+#  pragma warning(push)
+#  pragma warning(disable: 4512) // assignment operator could not be generated.
+#endif
 struct ostream_fun
 {
     ostream_fun(std::ostream &sout)
@@ -34,6 +38,9 @@ struct ostream_fun
 private:
     std::ostream & sout_;
 };
+#ifdef _MSC_VER
+#  pragma warning(pop)
+#endif
 
 template<typename Tree>
 void

test/sequence/transform_view.cpp

@@ -1,11 +1,14 @@
 /*=============================================================================
     Copyright (c) 2001-2011 Joel de Guzman
+    Copyright (c) 2022 Denis Mikhailov
 
     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 <boost/detail/lightweight_test.hpp>
 #include <boost/fusion/container/vector/vector.hpp>
+#include <boost/fusion/container/map/map.hpp>
+#include <boost/fusion/container/generation/make_map.hpp>
 #include <boost/fusion/adapted/mpl.hpp>
 #include <boost/fusion/sequence/io/out.hpp>
 #include <boost/fusion/container/generation/make_vector.hpp>
@@ -14,15 +17,29 @@
 #include <boost/fusion/sequence/intrinsic/begin.hpp>
 #include <boost/fusion/sequence/intrinsic/at.hpp>
 #include <boost/fusion/sequence/intrinsic/value_at.hpp>
+#include <boost/fusion/sequence/intrinsic/at_key.hpp>
+#include <boost/fusion/sequence/intrinsic/value_at_key.hpp>
+#include <boost/fusion/sequence/intrinsic/has_key.hpp>
+#include <boost/fusion/sequence/intrinsic/begin.hpp>
 #include <boost/fusion/iterator/next.hpp>
 #include <boost/fusion/iterator/prior.hpp>
 #include <boost/fusion/iterator/advance.hpp>
 #include <boost/fusion/iterator/deref.hpp>
 #include <boost/fusion/iterator/distance.hpp>
+#include <boost/fusion/iterator/key_of.hpp>
+#include <boost/fusion/iterator/deref_data.hpp>
+#include <boost/fusion/iterator/value_of_data.hpp>
+#include <boost/fusion/support/pair.hpp>
+#include <boost/fusion/support/category_of.hpp>
 
 #include <boost/mpl/range_c.hpp>
 #include <boost/mpl/assert.hpp>
+#include <boost/mpl/at.hpp>
+#include <boost/mpl/map.hpp>
 #include <boost/type_traits/is_same.hpp>
+#include <boost/static_assert.hpp>
+#include <boost/typeof/typeof.hpp>
+#include <boost/type_traits/remove_reference.hpp>
 
 struct square
 {
@@ -60,6 +77,85 @@ struct add
     }
 };
 
+struct abstract
+{
+    virtual void foo() = 0;
+};
+
+struct functor
+{
+    typedef boost::fusion::pair<short, char> pair_0;
+    typedef boost::fusion::pair<double, std::string> pair_1;
+    typedef boost::fusion::pair<abstract, long> pair_2;
+
+    typedef boost::mpl::map<
+        boost::mpl::pair< boost::fusion::pair<int, char> , pair_0>
+      , boost::mpl::pair< pair_1 , pair_1>
+      , boost::mpl::pair< boost::fusion::pair<abstract, int> , pair_2>
+    > m;
+
+    template<typename Sig>
+    struct result;
+
+    template<class F, class T>
+    struct result<F(T)> 
+        : boost::mpl::at<
+              m,
+              typename boost::remove_reference<T>::type
+          >
+    {};
+
+    pair_0 operator() (const boost::fusion::pair<int, char>& arg) const
+    {
+        return pair_0(arg.second);
+    }
+    
+    pair_1 operator() (const pair_1 & arg) const
+    {
+        return pair_1(arg.second + "_transformed");
+    }
+
+    pair_2 operator() (const boost::fusion::pair<abstract, int>& arg) const
+    {
+        return pair_2(arg.second);
+    }
+};
+
+struct simple_identity
+{
+    template<typename Sig>
+    struct result;
+
+    template<typename U>
+    struct result<simple_identity(U)>
+    {
+        typedef U type;
+    };
+
+    template<typename T>
+    T& operator() (T& arg) const 
+    {
+        return arg;
+    }
+};
+
+struct simple_identity_nonref
+{
+    template<typename Sig>
+    struct result;
+
+    template<typename U>
+    struct result<simple_identity_nonref(U)>
+    : boost::remove_reference<U>
+    {};
+
+    template<typename T>
+    T operator() (T arg) const 
+    {
+        return arg;
+    }
+};
+
 int
 main()
 {
@@ -110,6 +206,183 @@ main()
         BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_at_c<xform_type, 0>::type, int>));
     }
 
+    /// Associative
+    {
+        typedef map<
+            pair<int, char>
+          , pair<double, std::string>
+          , pair<abstract, int> >
+        map_type;
+        typedef transform_view<map_type, functor> transformed_type;
+
+        BOOST_MPL_ASSERT((traits::is_associative<transformed_type>));
+        BOOST_MPL_ASSERT((traits::is_random_access<transformed_type>));
+
+        map_type m(
+            make_pair<int>('X')
+          , make_pair<double>("Men")
+          , make_pair<abstract>(2));
+        transformed_type t(m, functor());
+
+        std::cout << at_key<short>(t) << std::endl;
+        std::cout << at_key<double>(t) << std::endl;
+        std::cout << at_key<abstract>(t) << std::endl;
+
+        BOOST_TEST(at_key<short>(t) == 'X');
+        BOOST_TEST(at_key<double>(t) == "Men_transformed");
+        BOOST_TEST(at_key<abstract>(t) == 2);
+
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, short>::type, char>::value));
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, double>::type, std::string>::value));
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, abstract>::type, long>::value));
+
+        std::cout << t << std::endl;
+
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, short>::value));
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, double>::value));
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, abstract>::value));
+        BOOST_STATIC_ASSERT((!boost::fusion::result_of::has_key<transformed_type, std::string>::value));
+
+        std::cout << deref_data(begin(t)) << std::endl;
+        std::cout << deref_data(boost::fusion::next(begin(t))) << std::endl;
+
+        BOOST_TEST(deref_data(begin(t)) == 'X');
+        BOOST_TEST(deref_data(boost::fusion::next(begin(t))) == "Men_transformed");
+        BOOST_TEST(deref_data(boost::fusion::next(next(begin(t)))) == 2);
+
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::begin<transformed_type>::type>::type, short>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type, double>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::next<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type>::type, abstract>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::begin<transformed_type>::type>::type, char>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type, std::string>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::next<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type>::type, long>::value));
+
+        // Test random access interface.
+        pair<short, char> a = at_c<0>(t); (void) a;
+        pair<double, std::string> b = at_c<1>(t);
+        pair<abstract, int> c = at_c<2>(t);
+        (void)c;
+
+        typedef boost::fusion::result_of::begin<transformed_type>::type first;
+        typedef boost::fusion::result_of::next<first>::type second;
+        typedef boost::fusion::result_of::next<second>::type third;
+
+        BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<first>::type, boost::fusion::pair<short, char> >));
+        BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<second>::type, boost::fusion::pair<double, std::string> >));
+        BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<third>::type, boost::fusion::pair<abstract, long> >));
+    }
+
+    {
+        typedef map<
+            pair<int, char>
+          , pair<double, std::string>
+          , pair<abstract, int> >
+        map_type;
+        typedef transform_view<map_type, simple_identity> transformed_type;
+
+        BOOST_MPL_ASSERT((traits::is_associative<transformed_type>));
+        BOOST_MPL_ASSERT((traits::is_random_access<transformed_type>));
+
+        map_type m(
+            make_pair<int>('X')
+          , make_pair<double>("Men")
+          , make_pair<abstract>(2));
+        transformed_type t(m, simple_identity());
+
+        std::cout << at_key<int>(t) << std::endl;
+        std::cout << at_key<double>(t) << std::endl;
+        std::cout << at_key<abstract>(t) << std::endl;
+
+        BOOST_TEST(at_key<int>(t) == 'X');
+        BOOST_TEST(at_key<double>(t) == "Men");
+        BOOST_TEST(at_key<abstract>(t) == 2);
+
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, int>::type, char>::value));
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, double>::type, std::string>::value));
+        BOOST_STATIC_ASSERT((
+            boost::is_same<boost::fusion::result_of::value_at_key<transformed_type, abstract>::type, int>::value));
+
+        std::cout << t << std::endl;
+
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, int>::value));
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, double>::value));
+        BOOST_STATIC_ASSERT((boost::fusion::result_of::has_key<transformed_type, abstract>::value));
+        BOOST_STATIC_ASSERT((!boost::fusion::result_of::has_key<transformed_type, std::string>::value));
+
+        std::cout << deref_data(begin(t)) << std::endl;
+        std::cout << deref_data(boost::fusion::next(begin(t))) << std::endl;
+
+        BOOST_TEST(deref_data(begin(t)) == 'X');
+        BOOST_TEST(deref_data(boost::fusion::next(begin(t))) == "Men");
+        BOOST_TEST(deref_data(boost::fusion::next(next(begin(t)))) == 2);
+
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::begin<transformed_type>::type>::type, int>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type, double>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::key_of<boost::fusion::result_of::next<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type>::type, abstract>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::begin<transformed_type>::type>::type, char>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type, std::string>::value));
+        BOOST_STATIC_ASSERT((boost::is_same<boost::fusion::result_of::value_of_data<boost::fusion::result_of::next<boost::fusion::result_of::next<boost::fusion::result_of::begin<transformed_type>::type>::type>::type>::type, int>::value));
+
+        // Test random access interface.
+        pair<int, char> a = at_c<0>(t); (void) a;
+        pair<double, std::string> b = at_c<1>(t);
+        pair<abstract, int> c = at_c<2>(t);
+        (void)c;
+
+        typedef boost::fusion::result_of::begin<transformed_type>::type first;
+        typedef boost::fusion::result_of::next<first>::type second;
+        typedef boost::fusion::result_of::next<second>::type third;
+
+        // BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<first>::type, boost::fusion::pair<int, char> >));
+        // BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<second>::type, boost::fusion::pair<double, std::string> >));
+        // BOOST_MPL_ASSERT((boost::is_same<boost::fusion::result_of::value_of<third>::type, boost::fusion::pair<abstract, int> >));
+    }
+
+    {
+        // compile test only
+        // make sure result_of::deref_data returns a reference
+        typedef map<pair<float, int> > map_type;
+        typedef transform_view<map_type, simple_identity> transformed_type;
+        typedef boost::fusion::result_of::begin<transformed_type>::type i_type;
+        typedef boost::fusion::result_of::deref_data<i_type>::type r_type;
+        BOOST_STATIC_ASSERT((boost::is_same<r_type, int&>::value));
+    }
+
+    {
+        // compile test only
+        // make sure result_of::deref_data is const correct
+        typedef map<pair<float, int> > const map_type;
+        typedef transform_view<map_type, simple_identity> transformed_type;
+        typedef boost::fusion::result_of::begin<transformed_type>::type i_type;
+        typedef boost::fusion::result_of::deref_data<i_type>::type r_type;
+        BOOST_STATIC_ASSERT((boost::is_same<r_type, int const&>::value));
+    }
+
+    {
+        // compile test only
+        // make sure result_of::deref_data will not return a reference to temp object
+        typedef map<pair<float, int> > const map_type;
+        typedef transform_view<map_type, simple_identity_nonref> transformed_type;
+        typedef boost::fusion::result_of::begin<transformed_type>::type i_type;
+        typedef boost::fusion::result_of::deref_data<i_type>::type r_type;
+        BOOST_STATIC_ASSERT((boost::is_same<r_type, int>::value));
+    }
+
+    {
+        // compile test only
+        // make sure result_of::deref_data will not const for non-constant references
+        typedef map<pair<float, int&> > const map_type;
+        typedef transform_view<map_type, simple_identity> transformed_type;
+        typedef boost::fusion::result_of::begin<transformed_type>::type i_type;
+        typedef boost::fusion::result_of::deref_data<i_type>::type r_type;
+        BOOST_STATIC_ASSERT((boost::is_same<r_type, int&>::value));
+    }
+
     return boost::report_errors();
 }
 

test/support/detail/tag_of_fallback.cpp

@@ -0,0 +1,50 @@
+/*=============================================================================
+    Copyright (c) 2022 Denis Mikhailov
+
+    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 <boost/fusion/support/tag_of.hpp>
+#include <boost/static_assert.hpp>
+#include <boost/type_traits/is_same.hpp>
+#include <boost/core/enable_if.hpp>
+#include <boost/mpl/bool.hpp>
+#include <boost/mpl/if.hpp>
+
+namespace mpl = boost::mpl;
+
+template<typename T>
+struct my_is_implicitly_reflectable;
+
+namespace boost { namespace fusion
+{
+    struct boost_my_reflectable_tag;
+    namespace detail
+    {
+        template<typename Sequence>
+        struct tag_of_fallback<Sequence, typename boost::enable_if<boost::is_same<Sequence, Sequence> >::type>
+        {
+            typedef typename mpl::if_<my_is_implicitly_reflectable<Sequence>
+                         , boost_my_reflectable_tag
+                         , non_fusion_tag
+            >::type type;
+        };
+    }
+}}
+
+struct reflectable {};
+struct non_reflectable {};
+
+template<typename T>
+struct my_is_implicitly_reflectable : mpl::false_ {};
+template<>
+struct my_is_implicitly_reflectable<reflectable> : mpl::true_ {};
+
+typedef boost::fusion::traits::tag_of<reflectable>::type ReflectableTag;
+typedef boost::fusion::traits::tag_of<non_reflectable>::type NonReflectableTag;
+BOOST_STATIC_ASSERT((boost::is_same<ReflectableTag, boost::fusion::boost_my_reflectable_tag>::value));
+BOOST_STATIC_ASSERT((boost::is_same<NonReflectableTag, boost::fusion::non_fusion_tag>::value));
+
+int
+main() { }
+

test/support/make_pair_r-value.cpp

@@ -0,0 +1,24 @@
+/*=============================================================================
+    Copyright (c) 2022 niXman (github dot nixman at pm.me)
+    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 <boost/fusion/support/pair.hpp>
+
+struct noncopyable_type {
+    noncopyable_type(const noncopyable_type &) = delete;
+    noncopyable_type& operator=(const noncopyable_type &) = delete;
+#if !defined(BOOST_NO_CXX11_RVALUE_REFERENCES)
+    noncopyable_type(noncopyable_type &&) = default;
+    noncopyable_type& operaotr=(noncopyable_type &&) = default;
+#endif
+};
+
+int main() {
+    using namespace boost::fusion;
+
+    pair<int, noncopyable_type> val = make_pair<int>(noncopyable_type{});
+
+    return 0;
+}