add .clang-format and git-hooks

.clang-format

+---
+Language: Cpp
+# BasedOnStyle:	LLVM
+SortIncludes: false
+AccessModifierOffset: -2
+AlignAfterOpenBracket: DontAlign
+AlignConsecutiveAssignments: false
+AlignConsecutiveDeclarations: false
+DerivePointerAlignment: false
+PointerAlignment: Left
+ConstructorInitializerIndentWidth: 4
+AlignEscapedNewlinesLeft: true
+AlignTrailingComments: true
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortBlocksOnASingleLine: true
+AllowShortFunctionsOnASingleLine: false
+AllowShortIfStatementsOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakTemplateDeclarations: true
+BinPackArguments: false
+AlwaysBreakBeforeMultilineStrings: false
+BreakBeforeBinaryOperators: None
+BreakBeforeTernaryOperators: true
+BreakConstructorInitializersBeforeComma: false
+BinPackParameters: true
+ColumnLimit: 120
+ConstructorInitializerAllOnOneLineOrOnePerLine: true
+DerivePointerBinding: true
+ExperimentalAutoDetectBinPacking: false
+IndentCaseLabels: true
+MaxEmptyLinesToKeep: 1
+NamespaceIndentation: None
+ObjCSpaceBeforeProtocolList: false
+PenaltyBreakBeforeFirstCallParameter: 19
+PenaltyBreakComment: 200
+PenaltyBreakString: 1000
+PenaltyBreakFirstLessLess: 120
+PenaltyExcessCharacter: 1000000
+PenaltyReturnTypeOnItsOwnLine: 200
+AlwaysBreakAfterDefinitionReturnType: None
+AlwaysBreakAfterReturnType: None
+PointerBindsToType: true
+Cpp11BracedListStyle: true
+Standard:        Auto
+IndentWidth:     2
+TabWidth:        4
+UseTab:          Never
+BreakBeforeBraces: Custom
+BraceWrapping:
+  AfterClass:      false
+  AfterControlStatement: false
+  AfterEnum:       false
+  AfterFunction:   true
+  AfterNamespace:  false
+  AfterObjCDeclaration: false
+  AfterStruct:     false
+  AfterUnion:      false
+  AfterExternBlock: false
+  BeforeCatch:     false
+  BeforeElse:      false
+  IndentBraces:    false
+  SplitEmptyFunction: false
+  SplitEmptyRecord: false
+  SplitEmptyNamespace: false
+IndentFunctionDeclarationAfterType: true
+SpacesInParentheses: false
+SpacesInAngles: false
+SpaceInEmptyParentheses: false
+SpacesInCStyleCastParentheses: false
+SpaceAfterControlStatementKeyword: true
+SpaceBeforeAssignmentOperators: true
+SpacesBeforeTrailingComments: 2
+ContinuationIndentWidth: 4
+CommentPragmas:  '^lint'
+MacroBlockBegin: "
+
+END_CATCH_ERROR$"
+...

git-hooks/install-git-hooks.sh

+#!/bin/bash
+
+set -e
+
+ROOT=$(git rev-parse --show-toplevel)
+
+ln -sf $ROOT/git-hooks/pre-commit $ROOT/.git/hooks/pre-commit
+echo "installed git-hooks/pre-commit to .git/hooks/pre-commit"
+

git-hooks/pre-commit

+#!/bin/bash
+
+set -e
+
+ROOT=$(git rev-parse --show-toplevel)
+CLANG_FORMAT_HOOK_SCRIPT=$ROOT/git-hooks/pre-commit-clang-format
+$CLANG_FORMAT_HOOK_SCRIPT
+

git-hooks/pre-commit-clang-format

+#!/bin/bash
+
+CLANG_FORMAT=`which clang-format`
+SOURCE_FILE_EXTS=(.h .hh .hpp .hxx .c .cc .cpp .cxx)
+
+check_clang_format() {
+  if [ ! -x "$CLANG_FORMAT" ] ; then
+    echo "ERROR: clang-format executable not found."
+    exit 1
+  fi
+}
+
+# check whether the given file matches any of the extensions: case insensitive
+matches_extension() {
+  local file_name=$(basename "$1")
+  local file_ext=".${file_name##*.}"
+  local lowercase_file_ext=`echo $file_ext | awk '{print tolower($0)}'`
+  local source_file_ext
+  for source_file_ext in "${SOURCE_FILE_EXTS[@]}"
+  do
+    local lowercase_source_file_ext=`echo $source_file_ext | awk '{print tolower($0)}'`
+    [[ "$lowercase_file_ext" = "$lowercase_source_file_ext" ]] && return 0
+  done
+  return 1
+}
+
+_FORMATTED_FILES_CNT=0
+
+format_file() {
+  local source_file=$1
+  local formatted_file="${source_file}.formatted"
+  $CLANG_FORMAT -style=file $source_file > $formatted_file
+  cmp -s $source_file $formatted_file
+  if [ $? -ne 0 ]
+  then
+    mv $formatted_file $source_file && echo "formatted file $source_file"
+    let _FORMATTED_FILES_CNT++
+  else
+    rm -f $formatted_file
+  fi
+}
+
+_ROOT=$(git rev-parse --show-toplevel)
+format_staged_source_files() {
+  for file in $(git diff --staged --name-only)
+  do
+    file=$_ROOT/$file
+    matches_extension $file && format_file $file
+  done
+}
+
+# return 1 if there was any file actually formatted, which will break the `git commit` process.
+verify_format() {
+  if [ ${_FORMATTED_FILES_CNT} -gt 0 ]
+  then
+    echo "${_FORMATTED_FILES_CNT} files has been formatted."
+    exit 1
+  fi
+}
+
+main() {
+  check_clang_format
+  format_staged_source_files
+  verify_format
+}
+
+main