1# Coding Standard for the ANGLE Project 2 3## Google Style Guide 4 5We generally use the [Google C++ Style Guide](https://google.github.io/styleguide/cppguide.html) as a basis for 6our Coding Standard, however we will deviate from it in a few areas, as noted 7below. 8 9Items marked {DEV} indicate a deviation from the Google guidelines. Items marked 10{DO} are reiterating points from the Google guidelines. 11 12Before you upload code to Gerrit, use `git cl format` to auto-format your code. 13This will catch most of the trivial formatting errors and save you time. 14 15### [Header Files](https://google.github.io/styleguide/cppguide.html#Header_Files) 16 17* We use **`.h`** for C++ headers. 18* {DEV} #define guards should be of the form: `<PATH>_<FILE>_H_`. (Compiler 19 codebase is varied, including `<PROJECT>_` makes the names excessively 20 long). 21 22### [Scoping](https://google.github.io/styleguide/cppguide.html#Scoping) 23 24* {DO} avoid globally scoped variables, unless absolutely necessary. 25 26### [Classes](https://google.github.io/styleguide/cppguide.html#Classes) 27 28* {DEV} Inherit (privately) from angle::NonCopyable helper class (defined in 29 common/angleutils.h) to disable default copy and assignment operators. 30 31### [Other C++ Features](https://google.github.io/styleguide/cppguide.html#Other_C++_Features) 32 33* {DEV} all parameters passed by reference, except for STL containers (e.g. 34 std::vector, std::list), must be labeled `const`. For return parameters 35 other than STL containers, use a pointer. 36* {DO} avoid use of default arguments. 37* {DONT} use C++ exceptions, they are disabled in the builds and not caught. 38* {DO} use nullptr (instead of 0 or NULL) for pointers. 39* {DO} use size\_t for loop iterators and size values. 40* {DO} use uint8\_t pointers instead of void pointers to denote binary data. 41* {DO} use C++11/14 according to the [Chromium c++ 11/14 guide] 42 (http://chromium-cpp.appspot.com/). 43 44### [Naming](https://google.github.io/styleguide/cppguide.html#Naming) 45 46#### File Names 47 48* {DEV} Filenames should be all lowercase and can include underscores (`_`). 49 If the file is an implementation of a class, the filename may be capitalized 50 the same as the major class. 51* {DEV} We use .cpp (instead of .cc), .h and .inl (inlined files) for C++ 52 files and headers. 53 54#### Directory Names 55* Directory names should be all lowercase, unless following an externally 56 imposed capitalization (eg include/EGL, or src/libGLESv2, etc) 57 58#### Variable Names 59 60Use the following guidelines, they do deviate somewhat from the [Google 61guidelines](https://google.github.io/styleguide/cppguide.html#Naming). 62 63* Class and type names: start with capital letter and use CamelCase. 64* {DEV} Class member variables: use an **`m`** prefix instead of trailing 65underscore and use CamelCase. 66* Global variables (if they must be used): use a **`g`** prefix. 67* {DEV} Variable names: start with lower case and use CamelCase (chosen for consistency) 68* {DEV} Function names: Member functions start with lower case and use CamelCase. Non-member and static member functions start with capital letter and 69use CamelCase (chosen for consistency) 70* {DO} Constants: start with a **`k`** and use CamelCase 71* Namespaces: short names. use all lower case 72* Enum Names: use class enums when possible. The values should be uppercase with underscores or CamelCase. 73* Macros: all uppercase with underscores 74* Exceptions to naming: use common sense! 75 76### [Comments](https://google.github.io/styleguide/cppguide.html#Comments) 77 78* {DO} read and follow Google's recommendations. 79* Each file **must** start with the following boilerplate notice: 80 81``` 82// 83// Copyright $YEAR The ANGLE Project Authors. All rights reserved. 84// Use of this source code is governed by a BSD-style license that can be 85// found in the LICENSE file. 86// 87``` 88 89* $YEAR should be set to the current year at the time a file is created, and not changed thereafter. 90 91### [Formatting](https://google.github.io/styleguide/cppguide.html#Formatting) 92 93* {DEV} Avoid excessively long lines. Please keep lines under 100 columns 94 long. 95* Use unix-style newlines. 96* {DO} use only spaces. No tab characters. Configure your editor to emit 97 spaces when you hit the TAB-key. 98* {DEV} indent 4 spaces at a time. 99* conditionals: place space outside the parenthesis. No spaces inside. 100* switch statements: use the output of `git cl format`. 101* class format(eg private, public, protected): indent by 2 spaces. Regular 102 4-space indent from the outer scope for declarations/definitions. 103* pointers and references: **`*`** and **`&`** tight against the variable 104* namespaces: are not indented. 105* extern code blocks: are not indented. 106* {DEV} braces should go on a separate line, except for functions defined in a 107 header file where the whole function declaration and definition fit on one 108 line. 109 110Examples: 111 112``` 113if (conditional) 114{ 115 stuff(); 116} 117else 118{ 119 otherstuff() 120} 121``` 122 123``` 124switch (conditional) 125{ 126 case foo: 127 dostuff(); 128 break; 129 case bar: 130 otherstuff(); 131 break; 132 default: 133 WTFBBQ(); 134} 135``` 136 137``` 138class MyClass : public Foo 139{ 140 public: 141 MyClass(); 142 ~MyClass() {}; 143 private: 144 DISALLOW_COPY_AND_ASSIGN(MyClass); 145}; 146``` 147 148``` 149char *c; 150const string &str; 151``` 152 153### [Exceptions to the Rules](https://google.github.io/styleguide/cppguide.html#Exceptions_to_the_Rules) 154 155* If modifying pre-existing code that does not match the standard, the altered 156 portions of the code should be changed to match the standard. 157 158### Generated Source Files 159 160Prefer storing generated sources as baked files in the repository. Avoid using 161GN actions to run Python scripts. 162 163**Definition:** 164 165Sometimes helper scripts can create compilable sources more easily from XML or 166JSON data sources than maintaining source files by hand. These scripts are often 167written in Python and output generated sources. 168 169**Decision** 170 171Storing generated sources in the repository makes integration easier for non-GN 172users. Python scripts can be expensive and slow to run at compile-time. 173Generated sources can be a pain point for messing up builds. 174 175It could be possible to solve the build clobbering problem. And we could replace 176Python with something faster. But to allow for easier integration with our tools 177and customers we should bake generated files into the repository. 178