Various code style automation for dpctl

1. `flake8`, `isort` jobs added to check for Python code style for new PRs against `master`, `gold/2021`, `release` branches.
2. `black` max line width changed to 80 chars.
3. `flake8` and `isort` configs added.
4. `pre-commit` hooks added to make it possible to run all these checks prior to pushing code.
5. `CONTRIBUTION.md` updated.

.flake8

@@ -0,0 +1,28 @@
+[flake8]
+filename = *.py, *.pyx
+max_line_length = 80
+max-doc-length = 80
+extend-ignore = E203, W503
+show-source = True
+
+exclude =
+    versioneer.py
+    dpctl/_version.py
+    build
+    conda.recipe
+    .git
+
+per-file-ignores =
+    dpctl/_sycl_context.pyx: E999, E225, E227
+    dpctl/_sycl_device.pyx: E999, E225
+    dpctl/_sycl_device_factory.pyx: E999, E225
+    dpctl/_sycl_event.pyx: E999, E225
+    dpctl/_sycl_platform.pyx: E999, E225
+    dpctl/_sycl_queue.pyx: E999, E225, E226, E227
+    dpctl/_sycl_queue_manager.pyx: E999, E225
+    dpctl/memory/_memory.pyx: E999, E225, E226, E227
+    dpctl/program/_program.pyx: E999, E225, E226, E227
+    dpctl/tensor/numpy_usm_shared.py: F821
+    examples/cython/sycl_buffer/_buffer_example.pyx: E999, E225, E402
+    examples/cython/sycl_direct_linkage/_buffer_example.pyx: E999, E225, E402
+    examples/cython/usm_memory/blackscholes.pyx: E999, E225, E226, E402

.github/workflows/cpp_style_checks.yml

@@ -0,0 +1,22 @@
+# This is a workflow to format C/C++ sources with clang-format
+
+name: C++ Code Style
+
+# Controls when the action will run. Triggers the workflow on push or pull request
+# events but only for the master branch
+on:
+  pull_request:
+  push:
+    branches: [master]
+
+jobs:
+  formatting-check:
+    name: clang-format
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v2
+    - name: Run clang-format style check for C/C++ programs.
+      uses: jidicula/clang-format-action@v3.1.0
+      with:
+        clang-format-version: '11'
+        check-path: 'dpctl-capi'

.github/workflows/python_style_checks.yml

@@ -0,0 +1,58 @@
+# This is a workflow to format Python code with black formatter
+
+name: Python Code Style
+
+# Controls when the action will run. Triggers the workflow on push or pull request
+# events but only for the master branch
+on:
+  pull_request:
+  push:
+    branches: [master]
+
+# A workflow run is made up of one or more jobs that can run sequentially or in parallel
+jobs:
+  # The isort job sorts all imports in .py, .pyx, .pxd files
+  isort:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-python@v2
+      - uses: jamescurtin/isort-action@master
+        with:
+          args: ". --check-only"
+
+  black:
+    # The type of runner that the job will run on
+    runs-on: ubuntu-latest
+
+    # Steps represent a sequence of tasks that will be executed as part of the job
+    steps:
+      # Checks-out your repository under $GITHUB_WORKSPACE, so your job can access it
+      - uses: actions/checkout@v2
+      # Set up a Python environment for use in actions
+      - uses: actions/setup-python@v2
+
+      # Run black code formatter
+      - uses: psf/black@21.4b2
+        with:
+          args: ". --check"
+
+  flake8:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        python-version: [3.7]
+
+    steps:
+    - uses: actions/checkout@v2
+    - name: Set up Python ${{ matrix.python-version }}
+      uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+    - name: Install dependencies
+      run: |
+        python -m pip install --upgrade pip
+        pip install flake8
+    - name: Lint with flake8
+      uses: py-actions/flake8@v1

.pre-commit-config.yaml

@@ -7,3 +7,32 @@ repos:
     -   id: bandit
         pass_filenames: false
         args: ["-r", "dpctl", "-lll"]
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.3.0
+    hooks:
+    -   id: end-of-file-fixer
+    -   id: trailing-whitespace
+-   repo: https://github.com/psf/black
+    rev: 21.4b2
+    hooks:
+    -   id: black
+        exclude: "versioneer.py|dpctl/_version.py"
+-   repo: https://github.com/pycqa/isort
+    rev: 5.8.0
+    hooks:
+    -   id: isort
+        name: isort (python)
+    -   id: isort
+        name: isort (cython)
+        types: [cython]
+    -   id: isort
+        name: isort (pyi)
+        types: [pyi]
+-   repo: https://gitlab.com/pycqa/flake8
+    rev: 3.9.1
+    hooks:
+    -   id: flake8
+-   repo: https://github.com/pocc/pre-commit-hooks
+    rev: v1.1.1
+    hooks:
+    -   id: clang-format

CONTRIBUTING.md

@@ -15,12 +15,30 @@ Run before each commit: `clang-format -style=file -i dpctl-capi/include/*.h dpct
 
 ### Python code style
 
-We use [black](https://black.readthedocs.io/en/stable/) code formatter.
+We use the following Python code style tools:
+- [black](https://black.readthedocs.io/en/stable/) code formatter.
+    - Revision: `20.8b1`.
+- [flake8](https://flake8.pycqa.org/en/latest/) linter.
+    - Revision `3.9.1`.
+- [isort](https://pycqa.github.io/isort/) import sorter.
+    - Revision `5.8.0`.
 
-- Revision: `20.8b1`.
-- See configuration in `pyproject.toml`.
+- Refer `pyproject.toml` and `.flake8` config files for current configurations.
 
-Run before each commit: `black .`
+Please run these three tools before each commit. Although, you may choose to
+do so manually, but it is much easier and preferable to automate these checks.
+Refer your IDE docs to set them up in your IDE, or you can set up `pre-commit`
+to add git hooks.
+
+### Setting up pre-commit
+
+A `.pre-commit-config.yaml` is included to run various check before you
+commit your code. Here are the steps to setup `pre-commit` in your workflow:
+
+- Install `pre-commit`: `pip install pre-commit`
+- Install the git hook scripts: `pre-commit install`
+
+That should be it!
 
 ### C/C++ File Headers
 
@@ -61,8 +79,9 @@ Few things to note about this format:
 - The copyright year should be updated every calendar year.
 - Each comment line should be a max of 80 chars.
 - A Doxygen `\file` tag describing the contents of the file must be provided.
-  Also note that the `\file` tag is inside a Doxygen comment block (defined by `///`
-  comment marker instead of the `//` comment marker used in the rest of the header.
+  Also note that the `\file` tag is inside a Doxygen comment block (
+  defined by `///` comment marker instead of the `//` comment marker used in the
+  rest of the header.
 
 ### Python File Headers
 
@@ -91,7 +110,8 @@ The copyright year should be updated every calendar year.
 
 ### Bandit
 
-We use [Bandit](https://github.com/PyCQA/bandit) to find common security issues in Python code.
+We use [Bandit](https://github.com/PyCQA/bandit) to find common security issues
+in Python code.
 
 Install: `pip install bandit`
 
@@ -101,18 +121,21 @@ Run before each commit: `bandit -r dpctl -lll`
 
 ## Code Coverage
 
-Implement python, cython and c++ file coverage using `coverage` and `llvm-cov` packages on Linux.
+Implement python, cython and c++ file coverage using `coverage` and `llvm-cov`
+packages on Linux.
 
 ### Using Code Coverage
 
-You need to install additional packages and add an environment variable to cover:
+You need to install additional packages and add an environment variable to
+cover:
 - conda install cmake
 - conda install coverage
 - conda install conda-forge::lcov
 - conda install conda-forge::gtest
 - export CODE_COVERAGE=ON
 
-CODE_COVERAGE allows you to build a debug version of dpctl and enable string tracing, which allows you to analyze strings to create a coverage report.
+CODE_COVERAGE allows you to build a debug version of dpctl and enable string
+tracing, which allows you to analyze strings to create a coverage report.
 It was added for the convenience of configuring the CI in the future.
 
 Installing the dpctl package:
@@ -121,34 +144,41 @@ Installing the dpctl package:
 It is important that there are no files of the old build in the folder.
 Use `git clean -xdf` to clean up the working tree.
 
-The coverage report will appear during the build in the console. This report contains information about c++ file coverage.
-The `dpctl-c-api-coverage` folder will appear in the root folder after installation.
-The folder contains a report on the coverage of c++ files in html format.
+The coverage report will appear during the build in the console. This report
+contains information about c++ file coverage.
+The `dpctl-c-api-coverage` folder will appear in the root folder after
+installation. The folder contains a report on the coverage of c++ files in html
+format.
 
 You need to run tests to cover the cython and python files:
 - coverage run -m unittest dpctl.tests
 
-The required flags for the command coverage run are contained in the file `.coveragerc`.
+The required flags for the command coverage run are contained in the file
+`.coveragerc`.
 
 The simplest reporting is a textual summary produced with report:
 - coverage report
 
-For each module executed, the report shows the count of executable statements, the number of those statements missed, and the resulting coverage, expressed as a percentage.
+For each module executed, the report shows the count of executable statements,
+the number of those statements missed, and the resulting coverage, expressed as
+a percentage.
 
 The `-m` flag also shows the line numbers of missing statements:
 - coverage report -m
 
 To create an annotated HTML listings with coverage results:
 - coverage html
 
-The `htmlcov` folder will appear in the root folder of the project. It contains reports on the coverage of python and cython files in html format.
+The `htmlcov` folder will appear in the root folder of the project. It contains
+reports on the coverage of python and cython files in html format.
 
 Erase previously collected coverage data:
 - coverage erase
 
 ### Error in the build process
 
-An error occurs during the dcptl build with the CODE_COVERAGE environment variable:
+An error occurs during the dcptl build with the CODE_COVERAGE environment
+variable:
 ```
 error: '../compat/unistd.h' file not found, did you mean 'compat/unistd.h'?
 #   include "../compat/unistd.h"

README.md

@@ -1,4 +1,5 @@
 [![Code style: black](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
+[![Imports: isort](https://img.shields.io/badge/%20imports-isort-%231674b1?style=flat&labelColor=ef8336)](https://pycqa.github.io/isort/)
 
 What?
 ====

pyproject.toml

@@ -1,2 +1,12 @@
 [tool.black]
-exclude = 'versioneer.py'
+exclude = "versioneer.py|dpctl/_version.py"
+line-length = 80
+
+[tool.isort]
+multi_line_output = 3
+include_trailing_comma = true
+force_grid_wrap = 0
+use_parentheses = true
+ensure_newline_before_comments = true
+line_length = 80
+skip = ["versioneer.py", "dpctl/_version.py"]

setup.cfg

@@ -1,8 +1,3 @@
-[flake8]
-max-line-length = 100
-ignore = E122,E123,E126,E127,E128,E731,E722
-exclude = build,dpctl/_version.py,tests,conda.recipe,.git,versioneer.py,benchmarks,.asv
-
 [tool:pytest]
 norecursedirs= .* *.egg* build dist conda.recipe
 addopts =