cpplint中filter参数的每个可选项的含义

ゝ一纸荒年。 2022-10-08 05:58 759阅读 0赞

### 文章目录 ###

*  前言
 *  filter是什么
 *  一个小实验
 *  自己指定筛选规则
 *  对照表格
 *  总结

# 前言 #

`cpplint` 是一款优秀的代码格式检查工具，有了它可以统一整个团队的代码风格，完整的工具就是一个Python脚本，如果安装了Python环境，直接使用 `pip install cpplint` 命令就可以安装了，非常的方便。

具体的使用方法可以通过 `cpplint --help` 查询，语法如下：

Syntax: cpplint.py [--verbose=#] [--output=emacs|eclipse|vs7|junit|sed|gsed]
                       [--filter=-x,+y,...]
                       [--counting=total|toplevel|detailed] [--root=subdir]
                       [--repository=path]
                       [--linelength=digits] [--headers=x,y,...]
                       [--recursive]
                       [--exclude=path]
                       [--extensions=hpp,cpp,...]
                       [--includeorder=default|standardcfirst]
                       [--quiet]
                       [--version]
            <file> [file] ...
    
      Style checker for C/C++ source files.
      This is a fork of the Google style checker with minor extensions.

其中有一句 `[--filter=-x,+y,...]` 就是本文总结的重点。

# filter是什么 #

这个filter究竟是什么呢？我将它强行解释成代码的“过滤器”，cpplint 是一款检查C++源代码风格的工具，遵循的是Google的编码风格，但是这些规则并不是对于所有人都合适，我们应该有目的进行选择，这个filter参数就是用来屏蔽或者启用一些规则的，我们还是从帮助文档里来看，其中有一段

filter=-x,+y,...
          Specify a comma-separated list of category-filters to apply: only
          error messages whose category names pass the filters will be printed.
          (Category names are printed with the message and look like
          "[whitespace/indent]".)  Filters are evaluated left to right.
          "-FOO" means "do not print categories that start with FOO".
          "+FOO" means "do print categories that start with FOO".
    
          Examples: --filter=-whitespace,+whitespace/braces
                    --filter=-whitespace,-runtime/printf,+runtime/printf_format
                    --filter=-,+build/include_what_you_use
    
          To see a list of all the categories used in cpplint, pass no arg:
             --filter=

这一段说明了filter参数的用法，就是以`+`或者 `-` 开头接着写规则名，就表示启用或者屏蔽这些规则，使用 `--filter=` 参数会列举出所有规则，我们来看一下：

C:\Users\Albert>cpplint --filter=
      build/class
      build/c++11
      build/c++14
      build/c++tr1
      build/deprecated
      build/endif_comment
      build/explicit_make_pair
      build/forward_decl
      build/header_guard
      build/include
      build/include_subdir
      build/include_alpha
      build/include_order
      build/include_what_you_use
      build/namespaces_headers
      build/namespaces_literals
      build/namespaces
      build/printf_format
      build/storage_class
      legal/copyright
      readability/alt_tokens
      readability/braces
      readability/casting
      readability/check
      readability/constructors
      readability/fn_size
      readability/inheritance
      readability/multiline_comment
      readability/multiline_string
      readability/namespace
      readability/nolint
      readability/nul
      readability/strings
      readability/todo
      readability/utf8
      runtime/arrays
      runtime/casting
      runtime/explicit
      runtime/int
      runtime/init
      runtime/invalid_increment
      runtime/member_string_references
      runtime/memset
      runtime/indentation_namespace
      runtime/operator
      runtime/printf
      runtime/printf_format
      runtime/references
      runtime/string
      runtime/threadsafe_fn
      runtime/vlog
      whitespace/blank_line
      whitespace/braces
      whitespace/comma
      whitespace/comments
      whitespace/empty_conditional_body
      whitespace/empty_if_body
      whitespace/empty_loop_body
      whitespace/end_of_line
      whitespace/ending_newline
      whitespace/forcolon
      whitespace/indent
      whitespace/line_length
      whitespace/newline
      whitespace/operators
      whitespace/parens
      whitespace/semicolon
      whitespace/tab
      whitespace/todo

这些选项还挺多的，一共有69项，但是现在有一个问题，我就一直没找到这些选项都代表什么含义，有些从名字可以推断出来，比如 `whitespace/line_length` 应该是指每行的长度限制，但是 `whitespace/comma` 单单从名字你知道他们是什么意思吗？所以我想简单总结一下。

# 一个小实验 #

都说cpplint非常好用，那么接下来我们看看这个工具要怎么用，先新建一个文件`teststyle`，在里面随便写一些C++代码，如下：

#include <iostream>
    #include <map>
    using namespace std;
    
    class Style
    { 
            public:
    		void test() { 
                cout << "This is style class" << endl;
            }
    
            void showName(string& extraMsg)
            { 
                cout << extraMsg << className << endl;
            }
    public:
        string className;
    };
    
    int main()
    { 
        Style s;
        string msg_fjakdjfkadjfkadjffjadfkasdjffajsdfkadvljakdjfakdfjkadfjkasdjfkasdfj="class_name:";
        s.showName( msg_fjakdjfkadjfkadjffjadfkasdjffajsdfkadvljakdjfakdfjkadfjkasdjfkasdfj );
    
        if(s.className == "")
        { 
            cout << "class name for s is empty." << endl;
        }
    
        return 0;
    }

这段临时“发挥”的代码可以正常编译运行，然后用`cpplint`工具检测一下：

> cpplint .\teststyle.cpp
    .\teststyle.cpp:0:  No copyright message found.  You should have a line: "Copyright [year] <Copyright Owner>"  [legal/copyright] [5]
    .\teststyle.cpp:3:  Do not use namespace using-directives.  Use using-declarations instead.  [build/namespaces] [5]
    .\teststyle.cpp:6:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
    .\teststyle.cpp:7:  public: should be indented +1 space inside class Style  [whitespace/indent] [3]
    .\teststyle.cpp:8:  Tab found; better to use spaces  [whitespace/tab] [1]
    .\teststyle.cpp:12:  Is this a non-const reference? If so, make const or use a pointer: string& extraMsg  [runtime/references] [2]
    .\teststyle.cpp:13:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
    .\teststyle.cpp:16:  public: should be indented +1 space inside class Style  [whitespace/indent] [3]
    .\teststyle.cpp:21:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
    .\teststyle.cpp:23:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
    .\teststyle.cpp:23:  Missing spaces around =  [whitespace/operators] [4]
    .\teststyle.cpp:24:  Lines should be <= 80 characters long  [whitespace/line_length] [2]
    .\teststyle.cpp:24:  Extra space after ( in function call  [whitespace/parens] [4]
    .\teststyle.cpp:24:  Extra space before )  [whitespace/parens] [2]
    .\teststyle.cpp:26:  Missing space before ( in if(  [whitespace/parens] [5]
    .\teststyle.cpp:27:  { should almost always be at the end of the previous line  [whitespace/braces] [4]
    .\teststyle.cpp:32:  Could not find a newline character at the end of the file.  [whitespace/ending_newline] [5]
    Done processing .\teststyle.cpp
    Total errors found: 17

这么一小段代码居然报出了17个错误，厉不厉害？刺不刺激？下面来逐个解释一下：

> .\\teststyle.cpp:0: No copyright message found. You should have a line: "Copyright \[year\] " \[legal/copyright\] \[5\]

`[legal/copyright]` 表示文件中应该有形如 `Copyright [year] <Copyright Owner>` 版权信息

> \\teststyle.cpp:3: Do not use namespace using-directives. Use using-declarations instead. \[build/namespaces\] \[5\]

`[legal/copyright]` 表示第3行 `using namespace std;` 应该使用 `using-declarations` 而不要使用 `using-directives`，这个规则可以简单的理解为使用命名空间，每次只引用其中的成员，而不要把整个命名空间都引入。

> .\\teststyle.cpp:6: \{ should almost always be at the end of the previous line \[whitespace/braces\] \[4\]

`[whitespace/braces]` 表示第6行的大括号应该放在上一行末尾

> .\\teststyle.cpp:7: public: should be indented +1 space inside class Style \[whitespace/indent\] \[3\]

`[whitespace/indent]` 表示第7行 `public:` 应该在行首只保留一个空格

> .\\teststyle.cpp:8: Tab found; better to use spaces \[whitespace/tab\] \[1\]

`[whitespace/tab]` 表示代码中第8行出现了Tab字符，应该使用空格代替

> .\\teststyle.cpp:12: Is this a non-const reference? If so, make const or use a pointer: string& extraMsg \[runtime/references\] \[2\]

`[runtime/references]` 表示代码第12行建议使用常引用

> .\\teststyle.cpp:23: Lines should be <= 80 characters long \[whitespace/line\_length\] \[2\]

`[whitespace/line_length]` 表示代码第23行长度超过了80个字符

> .\\teststyle.cpp:23: Missing spaces around = \[whitespace/operators\] \[4\]

`[whitespace/operators]` 表示代码第23行在赋值符号 `=` 前后应该有一个空格

> .\\teststyle.cpp:24: Extra space after ( in function call \[whitespace/parens\] \[4\]

`[whitespace/parens]` 表示代码第24行在小括号后面出现了多余的空格

> .\\teststyle.cpp:26: Missing space before ( in if( \[whitespace/parens\] \[5\]

`[whitespace/parens]` 表示代码第26行if后面缺少空格

> .\\teststyle.cpp:32: Could not find a newline character at the end of the file. \[whitespace/ending\_newline\] \[5\]

`[whitespace/ending_newline]` 表示32行，文件末尾应该是一个空行

按照上面`cpplint`提示修改代码如下：

// Copyright [2021] <Copyright albert>
    #include <iostream>
    #include <map>
    using std::cout;
    using std::endl;
    using std::string;
    
    class Style { 
     public:
        void test() { 
            cout << "This is style class" << endl;
        }
    
        void showName(const string& extraMsg) { 
            cout << extraMsg << className << endl;
        }
     public:
        string className;
    };
    
    int main() { 
        Style s;
        string msg = "class_name:";
        s.showName(msg);
    
        if (s.className == "") { 
            cout << "class name for s is empty." << endl;
        }
    
        return 0;
    }

# 自己指定筛选规则 #

有些人按照上面默认的规则修改代码之后感觉清爽了不少，而有些人却更加郁闷了，因为这些规则是google内部自己根据需要制定的，并不能满足所有人的需求，所以自己需要有目的的做出选择，比如我就决定项目中不写版权信息，那么再使用`cpplint` 时可以把检测版权信息的规则过滤掉：`cpplint --filter="-legal/copyright" .\teststyle.cpp`。

# 对照表格 #

总体来说规则还是很多的，想要在一段代码中展示出所有的情况不太容易，所以整理了下面的表格，对一些规则做了解释，因为有些情况我也没有遇到，所以先空着，后面再慢慢补充，这也是做这篇总结的目的，当有一种规则需求时先来查一下，越来越完整。

<table> 
 <thead> 
  <tr> 
   <th align="left">filter</th> 
   <th align="left">解释</th> 
  </tr> 
 </thead> 
 <tbody> 
  <tr> 
   <td align="left">build/class</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/c++11</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/c++14</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/c++tr1</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/deprecated</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/endif_comment</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/explicit_make_pair</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/forward_decl</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/header_guard</td> 
   <td align="left">①头文件需要添加只被包含一次的宏，<code>#ifndef</code>、<code>#define</code></td> 
  </tr> 
  <tr> 
   <td align="left">build/include</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/include_subdir</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/include_alpha</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/include_order</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/include_what_you_use</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/namespaces_headers</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/namespaces_literals</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/namespaces</td> 
   <td align="left">①不要引入整个命名空间，仅引入需要使用的成员</td> 
  </tr> 
  <tr> 
   <td align="left">build/printf_format</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">build/storage_class</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">legal/copyright</td> 
   <td align="left">①文件中缺少版权信息</td> 
  </tr> 
  <tr> 
   <td align="left">readability/alt_tokens</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/braces</td> 
   <td align="left">①如果if一个分支包含大括号，那么其他分支也应该包括大括号</td> 
  </tr> 
  <tr> 
   <td align="left">readability/casting</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/check</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/constructors</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/fn_size</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/inheritance</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/multiline_comment</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/multiline_string</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/namespace</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/nolint</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/nul</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/strings</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">readability/todo</td> 
   <td align="left">①TODO注释中应包括用户名</td> 
  </tr> 
  <tr> 
   <td align="left">readability/utf8</td> 
   <td align="left">①文件应该使用utf8编码</td> 
  </tr> 
  <tr> 
   <td align="left">runtime/arrays</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/casting</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/explicit</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/int</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/init</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/invalid_increment</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/member_string_references</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/memset</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/indentation_namespace</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/operator</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/printf</td> 
   <td align="left">①使用sprintf替换strcpy、strcat</td> 
  </tr> 
  <tr> 
   <td align="left">runtime/printf_format</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/references</td> 
   <td align="left">①确认是否要使用常引用</td> 
  </tr> 
  <tr> 
   <td align="left">runtime/string</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/threadsafe_fn</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">runtime/vlog</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/blank_line</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/braces</td> 
   <td align="left">①左大括号应该放在上一行末尾</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/comma</td> 
   <td align="left">①逗号后面应该有空格</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/comments</td> 
   <td align="left">①//后应该紧跟着一个空格</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/empty_conditional_body</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/empty_if_body</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/empty_loop_body</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/end_of_line</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/ending_newline</td> 
   <td align="left">①文件末尾需要空行</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/forcolon</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/indent</td> 
   <td align="left">①public、protected、private前需要1个空格</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/line_length</td> 
   <td align="left">①代码行长度有限制</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/newline</td> 
   <td align="left"></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/operators</td> 
   <td align="left">①操作符前后需要有空格</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/parens</td> 
   <td align="left">①if、while、for、switch后的小括号前需要有空格。②小括号中的首个参数前和最后参数尾不应有空格</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/semicolon</td> 
   <td align="left">①分号后缺少空格，比如<code>{ return 1;}</code></td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/tab</td> 
   <td align="left">①使用空格代替tab</td> 
  </tr> 
  <tr> 
   <td align="left">whitespace/todo</td> 
   <td align="left">①TODO注释前空格太多。②TODO注释中用户名后应该有一个空格</td> 
  </tr> 
 </tbody> 
</table>

# 总结 #

*  `cpplint` 是一个检查c++代码风格的小工具
 *  `cpplint.py` 其实是一个Python脚本文件，使用前可以先安装Python环境
 *  使用 `cpplint` 时默认遵循的是[Google的代码风格][Google]
 *  为了让代码检测符合自己的习惯，需要使用`--filter=`参数选项，有多种规则可以选择或者忽略
 *  `--filter=`中的规则是一个大类，比如 `whitespace/parens` 既检查小括号前缺少空格的情况，也会检查小括号中多空格的情况

--------------------

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[Google]: https://google.github.io/styleguide/cppguide.html
[_ _]: https://blog.csdn.net/albertsh/article/details/117393224