add clang format check (#10)

Co-authored-by: Jian Sun <[email protected]>

.clang-format

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+
+---
+BasedOnStyle: Google
+AlignAfterOpenBracket: 'AlwaysBreak'
+AllowAllConstructorInitializersOnNextLine: 'false'
+AllowAllParametersOfDeclarationOnNextLine: 'false'
+AlignConsecutiveMacros: 'true'
+AllowShortCaseLabelsOnASingleLine: 'true'
+AllowShortFunctionsOnASingleLine: 'None'
+AllowShortIfStatementsOnASingleLine: 'Never'
+AllowShortLoopsOnASingleLine: 'false'
+BreakBeforeBraces: Allman
+BinPackArguments: 'false'
+BinPackParameters: 'false'
+Cpp11BracedListStyle: 'false'
+ColumnLimit: 125 
+IndentWidth: 2
+IndentPPDirectives: BeforeHash
+NamespaceIndentation: All
+PackConstructorInitializers: 'Never'
+SpaceAfterTemplateKeyword: 'false'
+SpaceBeforeCtorInitializerColon: 'true'
+SpaceBeforeInheritanceColon: 'true'
+SpaceBeforeParens: ControlStatements
+SpaceBeforeRangeBasedForLoopColon: 'true'
+SpaceInEmptyBlock: true
+Standard: 'Latest'
+IncludeBlocks: Regroup
+IncludeCategories:
+  # CUDA, cuBLAS, LLVM, OpenMP headers
+  - Regex:           '<(cuda|cublas|llvm|omp)[[:alnum:].(-|_)*]+>'
+    Priority:        2
+  # External libraries headers
+  - Regex:           '<[[:alnum:].(-|_)*]+\/'
+    Priority:        3
+  # System headers
+  - Regex:           '<[[:alnum:].(-|_)*]+>'
+    Priority:        4
+  # Main, local, private headers
+  - Regex:           '".*'
+    Priority:        1

.github/workflows/clang_format.yml

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+name: Clang-Format
+
+on:
+  push:
+    branches:
+      - main
+
+jobs:
+  format:
+    name: Run Clang-Format
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Install Clang-Format
+        run: sudo apt-get update && sudo apt-get install clang-format && clang-format --version
+
+      - name: Check out code, run clang format, push changes
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Format code
+        run: |
+          find include -type f \( -name '*.hpp' -o -name '*.h' -o -name '*.cuh' -o -name '*.inl' \) -exec clang-format -i --style=file --verbose {} +
+          find src -type f \( -name '*.cu' -o -name '*.hpp' -o -name '*.h' -o -name '*.cpp' \) -exec clang-format -i --style=file --verbose {} +
+          find test -type f \( -name '*.hpp' -o -name '*.h' -o -name '*.cpp' -o -name '*.cuh' -o -name '*.cu' \) ! -path 'test/tutorial/*' -exec clang-format -i --style=file --verbose {} +
+
+      - name: Check for changes
+        id: check-changes
+        run: |
+          git diff --exit-code
+        continue-on-error: true
+
+      - name: Commit and push changes
+        # a failue of this step means changes were detected
+        if: steps.check-changes.outcome != 'success'
+        run: |
+          git config --global user.name "GitHub Actions"
+          git config --global user.email "[email protected]"
+          git commit -am "Auto-format code using Clang-Format" || echo "No changes to commit"
+
+      - name: Push changes to main-formatting branch
+        # a failue of this step means changes were detected
+        if: steps.check-changes.outcome != 'success'
+        run: |
+          git push origin HEAD:main-formatting
+
+      - name: Create Pull Request
+        # a failue of this step means changes were detected
+        if: steps.check-changes.outcome != 'success'
+        uses: peter-evans/create-pull-request@v3
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          commit-message: "Auto-format code using Clang-Format"
+          title: "Auto-format code changes"
+          body: "This is an automated pull request to apply code formatting using Clang-Format."
+          branch: "main-formatting"