Remove pybind dependencies from RaggedArc. (#842)

* Convert py::object and torch::IValue to each other

* Remove py::object from RaggedAny

* Remove py::object from RaggedArc

* Move files to torch directory

* remove unused files

* Add unit tests

* Remove v2 folder

* Remove unused code

* Remove unused files

* Fix review comments & fix github actions

* Check Ivalue contains RaggedAny

* Minor fixes

* Add attributes related unit test for FsaClass

* Fix mutable_grad in older pytorch version

* Fix github actions

* Fix github action PYTHONPATH

* Fix github action PYTHONPATH

* Link pybind11::embed

* import torch first (to fix macos github actions)

* try to fix macos ci

Author: pkufool

.github/workflows/build-doc.yml

@@ -88,7 +88,7 @@ jobs:
       - name: Build doc
         shell: bash
         run: |
-          export PYTHONPATH=$PWD/k2/python:$PWD/build/lib:$PYTHONPATH
+          export PYTHONPATH=$PWD/k2/torch/python:$PWD/build/lib:$PYTHONPATH
           echo "PYTHONPATH: $PYTHONPATH"
           cd docs
           python3 -m pip install -r ./requirements.txt

.github/workflows/run-tests-cpu.yml

@@ -105,12 +105,13 @@ jobs:
       - name: Display Build Information
         shell: bash
         run: |
-          export PYTHONPATH=$PWD/k2/python:$PWD/build/lib:$PYTHONPATH
+          export PYTHONPATH=$PWD/k2/torch/python:$PWD/build/lib:$PYTHONPATH
           python3 -m k2.version
 
       - name: Run Tests
         shell: bash
         run: |
+          export PYTHONPATH=$PWD/k2/torch/python:$PWD/build/lib:$PYTHONPATH
           cd build
           ctest --output-on-failure
           # default log level is INFO

.github/workflows/run-tests.yml

@@ -118,12 +118,13 @@ jobs:
       - name: Display Build Information
         shell: bash
         run: |
-          export PYTHONPATH=$PWD/k2/python:$PWD/build/lib:$PYTHONPATH
+          export PYTHONPATH=$PWD/k2/torch/python:$PWD/build/lib:$PYTHONPATH
           python3 -m k2.version
 
       - name: Run Tests
         shell: bash
         run: |
+          export PYTHONPATH=$PWD/k2/torch/python:$PWD/build/lib:$PYTHONPATH
           cd build
           ctest --output-on-failure
           # default log level is INFO

k2/CMakeLists.txt

@@ -1,2 +1,6 @@
 add_subdirectory(csrc)
-add_subdirectory(python)
+if(K2_USE_PYTORCH)
+  add_subdirectory(torch)
+else()
+  message(FATAL_ERROR "Please select a framework.")
+endif()