coding style: experimental use of a clang-format git pre-commit hook to force code convention

.clang-format

@@ -0,0 +1,64 @@
+---
+# BasedOnStyle:  LLVM
+AccessModifierOffset: -2
+AlignAfterOpenBracket: true
+AlignEscapedNewlinesLeft: false
+AlignOperands:   true
+AlignTrailingComments: true
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: false
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakAfterDefinitionReturnType: false
+AlwaysBreakBeforeMultilineStrings: false
+AlwaysBreakTemplateDeclarations: false
+BinPackArguments: true
+BinPackParameters: true
+BreakBeforeBinaryOperators: None
+BreakBeforeBraces: Attach
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: false
+ColumnLimit:     120
+CommentPragmas:  '^ IWYU pragma:'
+ConstructorInitializerAllOnOneLineOrOnePerLine: false
+ConstructorInitializerIndentWidth: 4
+ContinuationIndentWidth: 4
+Cpp11BracedListStyle: true
+DerivePointerAlignment: false
+DisableFormat:   false
+ExperimentalAutoDetectBinPacking: false
+ForEachMacros:   [ foreach, Q_FOREACH, BOOST_FOREACH ]
+IndentCaseLabels: false
+IndentFunctionDeclarationAfterType: false
+IndentWidth:     4
+IndentWrappedFunctionNames: false
+KeepEmptyLinesAtTheStartOfBlocks: true
+Language:        Cpp
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCBlockIndentWidth: 2
+ObjCSpaceAfterProperty: false
+ObjCSpaceBeforeProtocolList: true
+PenaltyBreakBeforeFirstCallParameter: 19
+PenaltyBreakComment: 300
+PenaltyBreakFirstLessLess: 120
+PenaltyBreakString: 1000
+PenaltyExcessCharacter: 1000000
+PenaltyReturnTypeOnItsOwnLine: 60
+PointerAlignment: Right
+SpaceAfterCStyleCast: false
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeParens: ControlStatements
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 1
+SpacesInAngles:  false
+SpacesInContainerLiterals: true
+SpacesInCStyleCastParentheses: false
+SpacesInParentheses: false
+SpacesInSquareBrackets: false
+Standard:        Cpp11
+TabWidth:        4
+UseTab:          Always
+...

.git-pre-commit

@@ -0,0 +1,50 @@
+#!/bin/bash
+
+# This hook purpose is to keep coding style consistent between all developers
+# It is automatically installed in .git/hooks folder by cmake on first run.
+
+# From https://github.com/tatsuhiro-t/nghttp2/blob/master/pre-commit
+
+function invalid-format-detected {
+        cat git-clang-format.diff
+        echo "*****************"
+        echo "$0: Invalid coding style detected (see git-clang-format.diff for issues). Please correct it using one of the following:"
+        echo "1) Apply patch located at git-clang-format.diff using:"
+        echo "  cd $(git rev-parse --show-toplevel) && $1"
+        echo "2) Use clang-format to correctly format source code using:"
+        echo "  $2"
+        echo "3) Reformat these lines manually."
+        echo "*** Aborting commit.***"
+        exit 1
+}
+function git-clang-format-diffing {
+    format_diff=$(which git-clang-format)
+    format_diff_options="--style=file"
+
+    #only diffing commited files, ignored staged one
+    $format_diff $format_diff_options --diff $(git --no-pager diff --cached --name-only) > git-clang-format.diff
+
+    if ! grep -q -E '(no modified files to format|clang-format did not modify any files)' git-clang-format.diff; then
+        invalid-format-detected "git apply git-clang-format.diff" "clang-format $format_diff_options -i <some_file.c>"
+    fi
+}
+
+function clang-format-diff-diffing {
+    format_diff=$(find /usr/bin/ -name 'clang-format-diff*' -type f | tail -n1)
+    format_diff_options="-style file"
+
+    git diff-index --cached --diff-filter=ACMR -p HEAD -- | $format_diff $format_diff_options -p1 > git-clang-format.diff
+    if [ -s git-clang-format.diff ]; then
+        invalid-format-detected "patch -p0 < git-clang-format.diff" "${format_diff/-diff/} $format_diff_options -i <some_file.cpp>"
+    fi
+}
+
+if which git-clang-format &>/dev/null; then
+    git-clang-format-diffing $@
+elif [ ! -z "$(find /usr/bin/ /usr/local/bin/ /opt/bin/ -name 'clang-format-diff*' -type f 2>/dev/null)" ]; then
+    # Warning! We need at least version 1.6...
+    clang-format-diff-diffing $@
+else
+    echo "$0: Please install clang-format (coding style checker) - could not find git-clang-format nor clang-format-diff in PATH."
+    exit 1
+fi

.gitignore

@@ -11,3 +11,4 @@ test-reports
 WORK
 Makefile
 OUTPUT
+git-clang-format.diff

prepare.py

@@ -151,6 +151,14 @@ def extract_libs_list():
     return list(set(l))
 
 
+def install_git_hook():
+    git_hook_path = ".git{sep}hooks{sep}pre-commit".format(sep=os.sep)
+    if os.path.isdir(".git{sep}hooks".format(sep=os.sep)) and not os.path.isfile(git_hook_path):
+        print("Installing Git pre-commit hook")
+        shutil.copyfile(".git-pre-commit", git_hook_path)
+        os.chmod(git_hook_path, 0755)
+
+
 def main(argv=None):
     if argv is None:
         argv = sys.argv
@@ -171,6 +179,8 @@ def main(argv=None):
                                 " architectures in list: {0}.".format(', '.join([repr(platform) for platform in platforms])))
     args, additional_args = argparser.parse_known_args()
 
+    install_git_hook()
+
     selected_platforms = []
     for platform in args.platform:
         if platform == 'all':