Add Initial Support for xeus-cpp-lite (#199)

Author: anutosh491

.github/workflows/deploy-github-page.yml

@@ -59,13 +59,15 @@ jobs:
           echo "PREFIX=$PREFIX" >> $GITHUB_ENV
           export CMAKE_PREFIX_PATH=$PREFIX
           export CMAKE_SYSTEM_PREFIX_PATH=$PREFIX
+          export SYSROOT_PATH=$HOME/emsdk/upstream/emscripten/cache/sysroot
 
           emcmake cmake \
             -DCMAKE_BUILD_TYPE=Release                        \
             -DCMAKE_PREFIX_PATH=$PREFIX                       \
             -DCMAKE_INSTALL_PREFIX=$PREFIX                    \
             -DXEUS_CPP_EMSCRIPTEN_WASM_BUILD=ON               \
             -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
+            -DSYSROOT_PATH=$SYSROOT_PATH                      \
             ..
           emmake make -j  ${{ env.ncpus }} install
 
@@ -76,6 +78,8 @@ jobs:
           micromamba activate xeus-lite-host
           python -m pip install jupyterlite-xeus
           jupyter lite build --XeusAddon.prefix=${{ env.PREFIX }} --output-dir dist
+          cp xcpp.data dist/extensions/@jupyterlite/xeus/static
+          cp $PREFIX/lib/libclangCppInterOp.so dist/extensions/@jupyterlite/xeus/static
           mkdir -p dist/files
           mv notebooks dist/files
           mv README.md dist/files

.github/workflows/main.yml

@@ -257,13 +257,15 @@ jobs:
           echo "PREFIX=$PREFIX" >> $GITHUB_ENV
           export CMAKE_PREFIX_PATH=$PREFIX
           export CMAKE_SYSTEM_PREFIX_PATH=$PREFIX
+          export SYSROOT_PATH=$HOME/emsdk/upstream/emscripten/cache/sysroot
 
           emcmake cmake \
             -DCMAKE_BUILD_TYPE=Release                        \
             -DCMAKE_PREFIX_PATH=$PREFIX                       \
             -DCMAKE_INSTALL_PREFIX=$PREFIX                    \
             -DXEUS_CPP_EMSCRIPTEN_WASM_BUILD=ON               \
             -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
+            -DSYSROOT_PATH=$SYSROOT_PATH                      \
             ..
           emmake make -j  ${{ env.ncpus }} install
 
@@ -274,6 +276,8 @@ jobs:
           micromamba activate xeus-lite-host
           python -m pip install jupyterlite-xeus
           jupyter lite build --XeusAddon.prefix=${{ env.PREFIX }}
+          cp xcpp.data _output/extensions/@jupyterlite/xeus/static
+          cp $PREFIX/lib/libclangCppInterOp.so _output/extensions/@jupyterlite/xeus/static
 
       - name: Setup tmate session
         if: ${{ failure() && runner.debug }}

CMakeLists.txt

@@ -84,7 +84,7 @@ if(EMSCRIPTEN)
     set(XEUS_CPP_USE_SHARED_XEUS_CPP OFF)
     set(XEUS_CPP_BUILD_TESTS OFF)
     # ENV (https://github.com/emscripten-core/emscripten/commit/6d9681ad04f60b41ef6345ab06c29bbc9eeb84e0)
-    set(EMSCRIPTEN_FEATURES "${EMSCRIPTEN_FEATURES} -s \"EXTRA_EXPORTED_RUNTIME_METHODS=[ENV']\"")
+    set(EMSCRIPTEN_FEATURES "${EMSCRIPTEN_FEATURES} -s \"EXPORTED_RUNTIME_METHODS=[ENV']\"")
 endif()
 
 # Dependencies
@@ -152,8 +152,22 @@ function(configure_kernel kernel)
 endfunction()
 
 message("Configure kernels: ...")
-configure_kernel("/share/jupyter/kernels/xcpp17/")
-configure_kernel("/share/jupyter/kernels/xcpp20/")
+if(EMSCRIPTEN)
+    # TODO: Currently jupyterlite-xeus and xeus-lite do not provide
+    # methods to fetch information from the arguments present in the
+    # generated emscripten kernel.
+    # The following needs to be done here :
+    # 1) We need to configure the kernel properly
+    #    Check issue https://github.com/compiler-research/xeus-cpp/issues/185.
+    # 2) Once the above is done we need to add support in jupyterlite-xeus & xeus-lite
+    #    to be able to deal with arguments present in kernel.json
+    # 3) Finally we should fetch the C++ version from the kernel.json file and
+    #    be able to pass it to our wasm interpreter rather than forcing a version.
+    configure_kernel("/share/jupyter/kernels/xcpp20/")
+else()
+    configure_kernel("/share/jupyter/kernels/xcpp17/")
+    configure_kernel("/share/jupyter/kernels/xcpp20/")
+endif()
 
 # Source files
 # ============
@@ -401,8 +415,24 @@ if(EMSCRIPTEN)
     xeus_cpp_set_kernel_options(xcpp)
     xeus_wasm_compile_options(xcpp)
     xeus_wasm_link_options(xcpp "web,worker")
+    # TODO: Remove the exported runtime methods
+    # after the next xeus release.
+    target_link_options(xcpp PUBLIC
+        -sEXPORTED_RUNTIME_METHODS=FS,PATH,ERRNO_CODES
+        # add sysroot location here
+        --preload-file ${SYSROOT_PATH}/include@/include
+    )
+    # TODO: Emscripten supports preloading files just once before it generates
+    # the xcpp.data file (containing the binary representation of the file(s) we
+    # want to include in our application).
+    # Hence although we are adding support for Standard Headers, Libraries etc
+    # through emscripten's sysroot for now, we need to do the following:
+    # 1) Enable CppInterOp to provide us with a resource dir.
+    # 2) If the above cannot be done, we can use the resource dir provided
+    #    by llvm on emscripten-forge but would involve adding a dependency.
+    # 3) Shift the resource dir and the sysroot to a common location.
+    # 4) Preload everything required together.
 endif()
-
 # Tests
 # =====
 
@@ -492,6 +522,7 @@ if(EMSCRIPTEN)
     install(FILES
             "$<TARGET_FILE_DIR:xcpp>/xcpp.js"
             "$<TARGET_FILE_DIR:xcpp>/xcpp.wasm"
+            "$<TARGET_FILE_DIR:xcpp>/xcpp.data"
             DESTINATION ${CMAKE_INSTALL_BINDIR})
 endif ()
 

README.md

@@ -87,13 +87,15 @@ pushd build
 export PREFIX=$MAMBA_ROOT_PREFIX/envs/xeus-cpp-wasm-host 
 export CMAKE_PREFIX_PATH=$PREFIX
 export CMAKE_SYSTEM_PREFIX_PATH=$PREFIX
+export SYSROOT_PATH=$HOME/emsdk/upstream/emscripten/cache/sysroot
 
 emcmake cmake \
         -DCMAKE_BUILD_TYPE=Release                        \
         -DCMAKE_PREFIX_PATH=$PREFIX                       \
         -DCMAKE_INSTALL_PREFIX=$PREFIX                    \
         -DXEUS_CPP_EMSCRIPTEN_WASM_BUILD=ON               \
         -DCMAKE_FIND_ROOT_PATH_MODE_PACKAGE=ON            \
+        -DSYSROOT_PATH=$SYSROOT_PATH                      \
         ..
 emmake make install
 ```
@@ -105,12 +107,20 @@ micromamba activate xeus-lite-host
 python -m pip install jupyterlite-xeus
 jupyter lite build --XeusAddon.prefix=$PREFIX
 ```
+
+We now need to shift necessary files like `xcpp.data` which contains the binary representation of the file(s)
+we want to include in our application. As of now this would contain all important files like Standard Headers,
+Libraries etc coming out of emscripten's sysroot. Assuming we are still inside build we should do the following
+```bash
+cp xcpp.data _output/extensions/@jupyterlite/xeus/static
+cp $PREFIX/lib/libclangCppInterOp.so _output/extensions/@jupyterlite/xeus/static
+```
+
 Once the Jupyter Lite site has built you can test the website locally by executing
 ```bash
 jupyter lite serve --XeusAddon.prefix=$PREFIX
 ```
 
-
 ## Trying it online
 
 To try out xeus-cpp interactively in your web browser, just click on the binder link:

src/xinterpreter.cpp

@@ -28,6 +28,9 @@ using Args = std::vector<const char*>;
 
 void* createInterpreter(const Args &ExtraArgs = {}) {
   Args ClangArgs = {/*"-xc++"*/"-v"}; // ? {"-Xclang", "-emit-llvm-only", "-Xclang", "-diagnostic-log-file", "-Xclang", "-", "-xc++"};
+#ifdef EMSCRIPTEN
+  ClangArgs.push_back("-std=c++20");
+#else
   if (std::find_if(ExtraArgs.begin(), ExtraArgs.end(), [](const std::string& s) {
     return s == "-resource-dir";}) == ExtraArgs.end()) {
     std::string resource_dir = Cpp::DetectResourceDir();
@@ -42,6 +45,7 @@ void* createInterpreter(const Args &ExtraArgs = {}) {
     ClangArgs.push_back("-isystem");
     ClangArgs.push_back(CxxInclude.c_str());
   }
+#endif
   ClangArgs.insert(ClangArgs.end(), ExtraArgs.begin(), ExtraArgs.end());
   // FIXME: We should process the kernel input options and conditionally pass
   // the gpu args here.
@@ -73,6 +77,7 @@ namespace xcpp
     static std::string get_stdopt()
     {
         // We need to find what's the C++ version the interpreter runs with.
+#ifndef EMSCRIPTEN
         const char* code = R"(
 int __get_cxx_version () {
 #if __cplusplus > 202302L
@@ -93,12 +98,13 @@ int __get_cxx_version () {
   }
 __get_cxx_version ()
       )";
-
         auto cxx_version = Cpp::Evaluate(code);
         return std::to_string(cxx_version);
+#else
+        return "20";
+#endif
     }
 
-
     interpreter::interpreter(int argc, const char* const* argv) :
         xmagics()
         , p_cout_strbuf(nullptr)
@@ -110,7 +116,6 @@ __get_cxx_version ()
         createInterpreter(Args(argv ? argv + 1 : argv, argv + argc));
         m_version = get_stdopt();
         redirect_output();
-        init_includes();
         init_preamble();
         init_magic();
     }
@@ -355,11 +360,6 @@ __get_cxx_version ()
         publish_stream("stderr", s);
     }
 
-    void interpreter::init_includes()
-    {
-        Cpp::AddIncludePath((xeus::prefix_path() + "/include/").c_str());
-    }
-
     void interpreter::init_preamble()
     {
         //NOLINTBEGIN(cppcoreguidelines-owning-memory)