zClang-Format

最近在考虑团队代码风格的问题，无意间发现了一个代码格式化神器“clang-format”工具

在了解clang-format工具之前，我们先来了解一下什么是clang，什么是LLVM，什么是GCC，什么又是GNU

GNU

从百度百科上可以看到，GNU是一个类unix操作系统，其内容软件完全以GPL协议发布。全称GNU’s Not Unix

GCC

gccegg-65

GCC是一套基于GNU系统开发的编译器，目前支持编译 C, C++, Objective-C,Fortran, Ada, Go, D等多种语言

其详细信息可以查看 GCC, the GNU Compiler Collection

LLVM

LLVM最初由美国UIUC大学的chris Lattner博士主持开展，之后Apple雇了Chris Lattner，LLVM相当于也就成了Apple官方支持的编译器。

LLVM提供了编译器的相关支持，以C++编写而成，用于优化以任意程序语言编写的程序的编译时间、链接时间、运行时间、空闲时间。

其详情可以查看 The LLVM Compiler Infrastructure

clang

clang是一个由Apple主导编写的，以LLVM为后端的前端C、C++、Objective-C语言编译器，他具有如下优势

编译速度快
内存占用小
兼容gcc

其详情可以查看 Clang: a C language family frontend for LLVM

clang-format

上面了解了一些基础知识点，现在开始本篇的主要内容介绍，使用clang-format工具格式化代码。本位以VSCode为例，作为讲解。

想要使用clang-format工具，我们需要一个名为“.clang-format”的配置文件，可以按照如下方法获取
1. vscode安装C/C++扩展，扩展程序将自动安装clang-format
2. 在vsc用户设置里面搜索clang，可以找到一个名为“C_Cpp: Clang_format_style”的选项，查看他的介绍，我们可以把代码格式化风格设置为如下几种
  - Visual Studio
  - LLVM
  - Google
  - Chromium
  - Mozilla
  - WebKit
  - file
3. 如果将代码设置成file，那将从当前目录或父目录中的.clang-format文件来格式化代码
4. 找到c/cc插件按照目录下的clang-format.exe工具，笔者的目录如下
  
  “C:\Users\\.vscode\extensions\ms-vscode.cpptools-1.5.1\LLVM\bin”
5. 打开命令行，输入.\clang-format.exe -style=“llvm” -dump-config > .clang-format命令，即可获取到一个名为.clang-format的文件，把此文件放到工程代码的根目录下，即可生效。
如果需要定制自己代码格式化风格，可以按照 Clang-Format Style Options文章修改.clang-format内容

笔者的.clang-format配置如下

---
Language: Cpp
# BasedOnStyle:  LLVM
AccessModifierOffset: -2
AlignAfterOpenBracket: Align
AlignConsecutiveMacros: AcrossEmptyLines
AlignConsecutiveAssignments: AcrossEmptyLines
AlignConsecutiveBitFields: AcrossEmptyLines
AlignConsecutiveDeclarations: AcrossEmptyLines
AlignEscapedNewlines: Left
AlignOperands: Align
AlignTrailingComments: true
AllowAllArgumentsOnNextLine: true
AllowAllConstructorInitializersOnNextLine: true
AllowAllParametersOfDeclarationOnNextLine: true
AllowShortEnumsOnASingleLine: false

AllowShortBlocksOnASingleLine: false
AllowShortCaseLabelsOnASingleLine: false
AllowShortFunctionsOnASingleLine: false

AllowShortLambdasOnASingleLine: All
AllowShortIfStatementsOnASingleLine: false
AllowShortLoopsOnASingleLine: false
AlwaysBreakAfterDefinitionReturnType: None
AlwaysBreakAfterReturnType: None
AlwaysBreakBeforeMultilineStrings: false
AlwaysBreakTemplateDeclarations: MultiLine
AttributeMacros:
    - __capability
BinPackArguments: false
BinPackParameters: false

BraceWrapping:
    AfterCaseLabel: true
    AfterClass: true
    AfterControlStatement: true
    AfterEnum: true
    AfterFunction: true
    AfterNamespace: true
    AfterObjCDeclaration: true
    AfterStruct: true
    AfterUnion: true
    AfterExternBlock: true
    BeforeCatch: true
    BeforeElse: true
    BeforeLambdaBody: true
    BeforeWhile: true
    IndentBraces: true
    SplitEmptyFunction: true
    SplitEmptyRecord: true
    SplitEmptyNamespace: true
BreakBeforeBinaryOperators: None
BreakBeforeConceptDeclarations: true
BreakBeforeBraces: Allman
BreakBeforeInheritanceComma: true
BreakInheritanceList: BeforeColon
BreakBeforeTernaryOperators: true
BreakConstructorInitializersBeforeComma: false
BreakConstructorInitializers: BeforeColon
BreakAfterJavaFieldAnnotations: false
BreakStringLiterals: false
ColumnLimit: 80
CommentPragmas: "^ IWYU pragma:"
CompactNamespaces: false
ConstructorInitializerAllOnOneLineOrOnePerLine: false
ConstructorInitializerIndentWidth: 4
ContinuationIndentWidth: 4
Cpp11BracedListStyle: true
DeriveLineEnding: true
DerivePointerAlignment: false
DisableFormat: false
EmptyLineBeforeAccessModifier: LogicalBlock
ExperimentalAutoDetectBinPacking: false
FixNamespaceComments: true
ForEachMacros:
    - foreach
    - Q_FOREACH
    - BOOST_FOREACH
StatementAttributeLikeMacros:
    - Q_EMIT
IncludeBlocks: Preserve
IncludeCategories:
    - Regex: '^"(llvm|llvm-c|clang|clang-c)/'
      Priority: 2
      SortPriority: 0
      CaseSensitive: false
    - Regex: '^(<|"(gtest|gmock|isl|json)/)'
      Priority: 3
      SortPriority: 0
      CaseSensitive: false
    - Regex: ".*"
      Priority: 1
      SortPriority: 0
      CaseSensitive: false
IncludeIsMainRegex: "(Test)?$"
IncludeIsMainSourceRegex: ""
IndentCaseLabels: false
IndentCaseBlocks: false
IndentGotoLabels: true
IndentPPDirectives: BeforeHash
IndentExternBlock: AfterExternBlock
IndentRequires: false
IndentWidth: 2
IndentWrappedFunctionNames: false
InsertTrailingCommas: None
JavaScriptQuotes: Leave
JavaScriptWrapImports: true
KeepEmptyLinesAtTheStartOfBlocks: false
MacroBlockBegin: ""
MacroBlockEnd: ""
MaxEmptyLinesToKeep: 1
NamespaceIndentation: None
ObjCBinPackProtocolList: Auto
ObjCBlockIndentWidth: 2
ObjCBreakBeforeNestedBlockParam: true
ObjCSpaceAfterProperty: false
ObjCSpaceBeforeProtocolList: true
PenaltyBreakAssignment: 2
PenaltyBreakBeforeFirstCallParameter: 19
PenaltyBreakComment: 300
PenaltyBreakFirstLessLess: 120
PenaltyBreakString: 1000
PenaltyBreakTemplateDeclaration: 10
PenaltyExcessCharacter: 1000000
PenaltyReturnTypeOnItsOwnLine: 60
PenaltyIndentedWhitespace: 0
PointerAlignment: Right
ReflowComments: true
SortIncludes: false
SortJavaStaticImport: Before
SortUsingDeclarations: false
SpaceAfterCStyleCast: false
SpaceAfterLogicalNot: false
SpaceAfterTemplateKeyword: true
SpaceBeforeAssignmentOperators: true
SpaceBeforeCaseColon: false
SpaceBeforeCpp11BracedList: true
SpaceBeforeCtorInitializerColon: true
SpaceBeforeInheritanceColon: true
SpaceBeforeParens: ControlStatements
SpaceAroundPointerQualifiers: Default
SpaceBeforeRangeBasedForLoopColon: true
SpaceInEmptyBlock: false
SpaceInEmptyParentheses: false
SpacesBeforeTrailingComments: 1
SpacesInAngles: false
SpacesInConditionalStatement: false
SpacesInContainerLiterals: true
SpacesInCStyleCastParentheses: false
SpacesInParentheses: false
SpacesInSquareBrackets: false
SpaceBeforeSquareBrackets: false
BitFieldColonSpacing: Both
Standard: Latest
StatementMacros:
    - Q_UNUSED
    - QT_REQUIRE_VERSION
TabWidth: 4
UseCRLF: false
UseTab: Never
WhitespaceSensitiveMacros:
    - STRINGIZE
    - PP_STRINGIZE
    - BOOST_PP_STRINGIZE
    - NS_SWIFT_NAME
    - CF_SWIFT_NAME
---