diff --git a/.github/Ubuntu/build.sh b/.github/Ubuntu/build.sh
new file mode 100755
index 00000000..1ff4d90f
--- /dev/null
+++ b/.github/Ubuntu/build.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+set -e
+
+function Usage {
+    echo "Usage: build.sh [-f]"
+}
+
+if [ $# -gt 1 ]; then
+    Usage
+    exit 1
+fi
+
+if [ $# -eq 1 ] && [ "$1" != "-f" ]; then
+    Usage
+    exit 1
+fi
+
+export VCPROOT="$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )"
+export PATH="${VCPROOT}/vl/cmd:${PATH}"
+export SHELL=/bin/bash
+
+vmake --make
+
+if [ "$1" == "-f" ]; then
+    vbuild -f
+else
+    vbuild -b
+fi
diff --git a/.github/Ubuntu/vl/cmd/vbuild b/.github/Ubuntu/vl/cmd/vbuild
new file mode 100755
index 00000000..eb0e191c
--- /dev/null
+++ b/.github/Ubuntu/vl/cmd/vbuild
@@ -0,0 +1,158 @@
+#!/bin/bash
+
+function Help {
+    echo "Usage:"
+    echo "--clean"
+    echo "    Clean generated files."
+    echo "-b, --build"
+    echo "    Incrementally build the current folder."
+    echo "-f, --full-build, -f"
+    echo "    Rebuild the current folder."
+    echo "-c, --build-coverage"
+    echo "    Rebuild the current folder with coverage."
+    echo "-fc, --full-build-coverage"
+    echo "    Rebuild the current folder with coverage."
+    echo "--build-gcc"
+    echo "    Incrementally build the current folder using G++."
+    echo "--full-build-gcc"
+    echo "    Rebuild the current folder using G++."
+    echo "-g, --generate"
+    echo "    Generate coverage data."
+    echo "-r, --read"
+    echo "    Read coverage data."
+}
+
+function Check {
+    if ! [ -a vmake ]; then
+        echo "Cannot find ./vmake ."
+        exit 1
+    fi
+}
+
+function Clean {
+    Check
+    make clean
+}
+
+function Build {
+    Check
+    make
+}
+
+function FullBuild {
+    Check
+    make clean
+    make
+}
+
+function BuildCoverage {
+    Check
+    make COVERAGE=YES
+}
+
+function FullBuildCoverage {
+    Check
+    make clean
+    make COVERAGE=YES
+}
+
+function BuildGCC {
+    Check
+    make USE_GCC=YES
+}
+
+function FullBuildGCC {
+    Check
+    make clean
+    make USE_GCC=YES
+}
+
+function Generate {
+    Check
+    lcov --directory ./Obj/ --base-directory . --gcov-tool ${VCPROOT}/vl/llvm-gcov.sh --capture -o ./Coverage/cov.info
+    genhtml ./Coverage/cov.info -o ./Coverage/HTML/
+}
+
+function Read {
+    Check
+    firefox `pwd`/Coverage/HTML/index.html
+    #sensible-browser ./Coverage/HTML/index.html 
+}
+
+case $1 in
+    --help)
+    Help
+    ;;
+
+    --clean)
+    Clean
+    ;;
+
+    -b|--build)
+    Build
+    ;;
+
+    -f|--full-build)
+    FullBuild
+    ;;
+
+    -c|--build-coverage)
+    BuildCoverage
+    ;;
+
+    -fc|--full-build-coverage)
+    FullBuildCoverage
+    ;;
+
+    --build-gcc)
+    BuildGCC
+    ;;
+
+    --full-build-gcc)
+    FullBuildGCC
+    ;;
+
+    -g|--generate)
+    Generate
+    ;;
+
+    -r|--read)
+    Read
+    ;;
+
+    *)
+    echo "Use --help for more information."
+    ;;
+esac
+
+# original makefile-cpp with gcc code coverage
+
+#COVERAGE?=NO
+#
+#ifeq ($(COVERAGE),NO)
+#CPP_LINK=clang++ -std=c++20 -pthread -g $(CPP_COMPILE_OPTIONS) -o $@ $^
+#else
+#CPP_LINK=g++ -std=c++20 -g -fprofile-arcs -pthread $(CPP_LINK_OPTIONS) -o $@ $^
+#endif
+#
+#ifeq ($(COVERAGE),NO)
+#CPP_COMPILE=clang++ -std=c++20 -g $(CPP_COMPILE_OPTIONS) -o $@ -c $<
+#else
+#CPP_COMPILE=g++ -std=c++20 -g -fprofile-arcs -ftest-coverage $(CPP_COMPILE_OPTIONS) -o $@ -c $<
+#endif
+
+#function Generate {
+#    Check
+#    PATTERN='^(.+)?\.o:\s*((.+)?.cpp).*$'
+#    CPP_FILES=`cat makefile \
+#        | grep -E ${PATTERN} \
+#        | sed -r -e 's%'${PATTERN}'%../\2%g'
+#        `
+#    rm -rf ./Coverage/*
+#    gcov -o ./Obj/ ${CPP_FILES} > /dev/null
+#    mv -f *.gcov ./Coverage/
+#    pushd ./Coverage > /dev/null
+#    lcov --directory ../Obj/ --capture --output-file lcov.info
+#    genhtml -o HTML lcov.info > /dev/null
+#    popd > /dev/null
+#}
\ No newline at end of file
diff --git a/.github/Ubuntu/vl/cmd/vmake b/.github/Ubuntu/vl/cmd/vmake
new file mode 100755
index 00000000..12ba752e
--- /dev/null
+++ b/.github/Ubuntu/vl/cmd/vmake
@@ -0,0 +1,30 @@
+#!/bin/bash
+
+function Help {
+    echo "Usage:"
+    echo "--make"
+    echo "    Update ./makefile and ./vmake.txt from ./vmake."
+}
+
+function Make {
+    if [ -a vmake ]; then
+        vt4 --preprocess ./vmake | vt4 --evaluate | ${SHELL} > makefile
+    else
+        echo "Cannot find ./vmake ."
+        exit 1
+    fi
+}
+
+case $1 in
+    --help)
+    Help
+    ;;
+
+    --make)
+    Make
+    ;;
+
+    *)
+    echo "Use --help for more information."
+    ;;
+esac
diff --git a/.github/Ubuntu/vl/cmd/vt4 b/.github/Ubuntu/vl/cmd/vt4
new file mode 100755
index 00000000..34e35db1
--- /dev/null
+++ b/.github/Ubuntu/vl/cmd/vt4
@@ -0,0 +1,123 @@
+#!/bin/bash
+
+function Help {
+    echo "Usage:"
+    echo "--preprocess <t4-template-file>"
+    echo "    Preprocess the template file and print to standard output."
+    echo "--evaluate <t4-template-file>"
+    echo "    Evaluate the preprocessed template file and print to standard output."
+}
+
+function Error {
+    (>&2 echo "Error(Row:${ROW_NUMBER}, Col:${COLUMN_NUMBER}): $1")
+    (>&2 echo "    In: ${LINE}")
+    exit 1
+}
+
+function Preprocess {
+    PATTERN='^\s*<#@\s*include\s*"([^"]*)"\s*#>\s*$'
+    cat $1 | while read -r LINE; do
+        INCLUDE_STAT=`echo "${LINE}" | grep -E ${PATTERN}`
+        if [[ "$INCLUDE_STAT" == "" ]]; then
+            echo "${LINE}"
+        else
+            INCLUDE_FILE=`echo "${LINE}" | sed -r -e 's%'${PATTERN}'%\1%g'`
+            INCLUDE_DIR=`dirname ${INCLUDE_FILE}`
+            INCLUDE_NAME=`basename ${INCLUDE_FILE}`
+
+            eval INCLUDE_DIR=$INCLUDE_DIR
+            pushd ${INCLUDE_DIR} > /dev/null
+            vt4 --preprocess "${INCLUDE_NAME}"
+            popd > /dev/null
+        fi
+    done
+}
+
+function Evaluate {
+    STATE_TEXT=1
+    STATE_CODE=2
+    STATE_EXPR=3
+
+    STATE=$STATE_TEXT
+    ROW_NUMBER=1
+
+    echo "#!/bin/bash"
+    echo ""
+
+    cat $1 | while read -r LINE; do
+        COLUMN_NUMBER=0
+
+        PARTS=`echo $LINE | sed -r -e 's%(<#=\s*|<#\s*|\s*#>)%\n\1\n%g'`
+        PARTS=`echo "$PARTS" | sed -r -e 's%^<#=\s*$%<#=%g;s%^<#\s*$%<#%g;s%^\s*#>$%#>%g'`
+        PURE_COMMAND=1
+
+        while read -r PART; do
+            case "$PART" in
+                "")
+                ;;
+
+                "<#")
+                if [ $STATE == $STATE_TEXT ]; then
+                    STATE=$STATE_CODE
+                else
+                    Error "\"<#\" and \"<#=\" cannot be embedded in each other."
+                fi
+                ;;
+
+                "<#=")
+                if [ $STATE == $STATE_TEXT ]; then
+                    STATE=$STATE_EXPR
+                else
+                    Error "\"<#\" and \"<#=\" cannot be embedded in each other."
+                fi
+                ;;
+
+                "#>")
+                if [ $STATE == $STATE_TEXT ]; then
+                    Error "Wrong place for \"#>\"."
+                else
+                    STATE=$STATE_TEXT
+                fi
+                ;;
+
+                *)
+                if [ $STATE == $STATE_CODE ]; then
+                    echo "${PART}"
+                elif [ $STATE == $STATE_EXPR ]; then
+                    PURE_COMMAND=0
+                    echo "echo -n ${PART}"
+                else
+                    PURE_COMMAND=0
+                    echo "echo -n '${PART}'"
+                fi
+                ;;
+            esac
+
+            COLUMN_NUMBER=`echo "$(($COLUMN_NUMBER+${#PARTS}))"`
+        done <<< "${PARTS}"
+
+        if ( [ "$LINE" == "" ] && [ $STATE == $STATE_TEXT ] ) || [ $PURE_COMMAND == 0 ]; then
+            echo 'echo ""'
+        fi
+        ROW_NUMBER=`echo "$(($ROW_NUMBER+1))"`
+    done
+}
+
+IFS=
+case $1 in
+    --help)
+    Help
+    ;;
+
+    --preprocess)
+    Preprocess $2
+    ;;
+
+    --evaluate)
+    Evaluate $2
+    ;;
+
+    *)
+    echo "Use --help for more information."
+    ;;
+esac
diff --git a/.github/Ubuntu/vl/cmd/vutil_CppDependencies b/.github/Ubuntu/vl/cmd/vutil_CppDependencies
new file mode 100755
index 00000000..b16f3dfb
--- /dev/null
+++ b/.github/Ubuntu/vl/cmd/vutil_CppDependencies
@@ -0,0 +1,3 @@
+#!/bin/bash
+
+echo `clang++ --std=c++20 $1 -MM $2` | sed -r -e 's%[\]\s*%%g'
diff --git a/.github/Ubuntu/vl/cmd/vutil_CppFromVcxproj b/.github/Ubuntu/vl/cmd/vutil_CppFromVcxproj
new file mode 100755
index 00000000..45689d82
--- /dev/null
+++ b/.github/Ubuntu/vl/cmd/vutil_CppFromVcxproj
@@ -0,0 +1,19 @@
+#!/bin/bash
+
+# read the input *.vcxproj
+if [ "$1" == "" ]; then
+    exit 0
+fi
+CONTENT=`cat $1`
+
+# extract all cpp files
+PATTERN='<ClCompile\s+Include="(\$\(MSBuildThisFileDirectory\))?([^"]+.cpp)"\s*/?\s*>'
+COMPILES=`echo "${CONTENT}" | grep -E ${PATTERN}`
+CPPS=`echo "${COMPILES}" | sed -r -e 's%\s*'${PATTERN}'\s*%\2%g'`
+
+# refine file names
+CPPS=`echo "${CPPS}" | sed -e 's%[\]%/%g'`
+CPPS=`echo "${CPPS}" | sed -e 's%^%'${PWD}/$(dirname $1)/'%g'`
+echo "${CPPS}" | while read -r CPP; do
+    realpath --relative-to="${PWD}" ${CPP}
+done
diff --git a/.github/Ubuntu/vl/makefile-cpp b/.github/Ubuntu/vl/makefile-cpp
new file mode 100644
index 00000000..7256e5d2
--- /dev/null
+++ b/.github/Ubuntu/vl/makefile-cpp
@@ -0,0 +1,20 @@
+COVERAGE?=NO
+USE_GCC?=NO
+
+# add "--stdlib=libc++" after bug #808086 is fixed
+
+ifeq ($(USE_GCC), YES)
+CPP_LINK=g++ -std=c++20 -g -pthread $(CPP_LINK_OPTIONS) -o $@ $^
+else ifeq ($(COVERAGE),NO)
+CPP_LINK=clang++ -std=c++20 -pthread -g $(CPP_COMPILE_OPTIONS) -o $@ $^
+else
+CPP_LINK=clang++ -std=c++20 -pthread -g --coverage $(CPP_LINK_OPTIONS) -o $@ $^
+endif
+
+ifeq ($(USE_GCC), YES)
+CPP_COMPILE=g++ -std=c++20 -g $(CPP_COMPILE_OPTIONS) -o $@ -c $<
+else ifeq ($(COVERAGE),NO)
+CPP_COMPILE=clang++ -std=c++20 -g $(CPP_COMPILE_OPTIONS) -o $@ -c $<
+else
+CPP_COMPILE=clang++ -std=c++20 -g -fprofile-arcs -ftest-coverage $(CPP_COMPILE_OPTIONS) -o $@ -c $<
+endif
diff --git a/.github/Ubuntu/vl/vmake-cpp b/.github/Ubuntu/vl/vmake-cpp
new file mode 100644
index 00000000..d8a52683
--- /dev/null
+++ b/.github/Ubuntu/vl/vmake-cpp
@@ -0,0 +1,75 @@
+<#
+if ! [ "$CPP_VCXPROJ" == "" ]; then
+    CPP_FILES=($(vutil_CppFromVcxproj $CPP_VCXPROJ))
+fi
+
+for CPP_VCXPROJ_ITEM in "${CPP_VCXPROJS[@]}"; do
+	CPP_FILES_FROM_VCXPROJ=($(vutil_CppFromVcxproj $CPP_VCXPROJ_ITEM))
+    CPP_FILES=(${CPP_FILES[@]} ${CPP_FILES_FROM_VCXPROJ[@]})
+done
+
+# Remove duplicated items (preserve the first occurrence, like LINQ Distinct)
+declare -A __vutil_seen_cpp_files
+__vutil_distinct_cpp_files=()
+for __vutil_cpp_file in "${CPP_FILES[@]}"; do
+    if [ "${__vutil_seen_cpp_files["${__vutil_cpp_file}"]+x}" == "" ]; then
+        __vutil_seen_cpp_files["${__vutil_cpp_file}"]=1
+        __vutil_distinct_cpp_files+=("${__vutil_cpp_file}")
+    fi
+done
+CPP_FILES=("${__vutil_distinct_cpp_files[@]}")
+unset __vutil_seen_cpp_files __vutil_distinct_cpp_files __vutil_cpp_file
+
+for CPP_REMOVE in "${CPP_REMOVES[@]}"; do
+    CPP_FILES=(${CPP_FILES[@]/$CPP_REMOVE})
+done
+
+for CPP_ADD in "${CPP_ADDS[@]}"; do
+    CPP_FILES=(${CPP_FILES[@]} $CPP_ADD)
+done
+
+CPP_FILE_LIST=("${CPP_FILES[@]}")
+printf -v CPP_FILES "%s\n" "${CPP_FILE_LIST[@]}"
+CPP_FILES=${CPP_FILES%?}
+
+O_FILES=`echo "${CPP_FILES}" | sed -r -e 's%([^/]*/)*([^/]+).cpp%./Obj/\2.o%g'`
+O_FILES=`echo ${O_FILES}`
+
+printf "%s\n" "${CPP_FILE_LIST[@]}" > vmake.txt
+#>
+.PHONY: all clean pre-build
+.DEFAULT_GOAL := all
+
+<#if ! [ "$CPP_COMPILE_OPTIONS" == "" ]; then#>
+CPP_COMPILE_OPTIONS=<#= $CPP_COMPILE_OPTIONS #>
+<#fi#>
+<#if ! [ "$CPP_LINK_OPTIONS" == "" ]; then#>
+CPP_LINK_OPTIONS = <#= $CPP_LINK_OPTIONS #>
+<#fi#>
+include $(VCPROOT)/vl/makefile-cpp
+
+pre-build:
+	if ! [ -d ./Bin ]; then mkdir ./Bin; fi
+	if ! [ -d ./Obj ]; then mkdir ./Obj; fi
+	if ! [ -d ./Coverage ]; then mkdir ./Coverage; fi
+<#for FOLDER in "${FOLDERS[@]}"; do#>
+	if ! [ -d <#= $FOLDER #> ]; then mkdir <#= $FOLDER #>; fi
+<#done#>
+
+clean:
+	if [ -d ./Bin ]; then rm -r ./Bin; fi
+	if [ -d ./Obj ]; then rm -r ./Obj; fi
+	if [ -d ./Coverage ]; then rm -r ./Coverage; fi
+<#for FOLDER in "${FOLDERS[@]}"; do#>
+	if [ -d ./<#= $FOLDER #> ]; then rm -r <#= $FOLDER #>; fi
+<#done#>
+
+all:pre-build <#= ${TARGETS[@]} #>
+
+<#= $CPP_TARGET #>:<#= ${O_FILES} #>
+	$(CPP_LINK)
+<#echo "${CPP_FILES}" | while read -r CPP_FILE; do#>
+
+./Obj/<#= `vutil_CppDependencies "${CPP_COMPILE_OPTIONS}" ${CPP_FILE}` #>
+	$(CPP_COMPILE)
+<#done#>