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# Coding Standard for the ANGLE Project
## Google Style Guide
We generally use the [Google C++ Style Guide]
(https://google.github.io/styleguide/cppguide.html) as a basis for
our Coding Standard, however we will deviate from it in a few areas, as noted
below.
Items marked {DEV} indicate a deviation from the Google guidelines. Items marked
{DO} are reiterating points from the Google guidelines.
Before you upload code to Gerrit, use `git cl format` to auto-format your code.
This will catch most of the trivial formatting errors and save you time.
### [Header Files](https://google.github.io/styleguide/cppguide.html#Header_Files)
* We will use **`.h`** for C++ headers.
* {DEV} #define guards should be of the form: `<PATH>_<FILE>_H_`. (Compiler
codebase is varied, including `<PROJECT>_` makes the names excessively
long).
### [Scoping](https://google.github.io/styleguide/cppguide.html#Scoping)
* {DO} avoid globally scoped variables, unless absolutely necessary.
### [Classes](https://google.github.io/styleguide/cppguide.html#Classes)
* {DEV} Inherit (privately) from angle::NonCopyable helper class (defined in
common/angleutils.h) to disable default copy and assignment operators.
### [Other C++ Features](https://google.github.io/styleguide/cppguide.html#Other_C++_Features)
* {DEV} all parameters passed by reference, except for STL containers (e.g.
std::vector, std::list), must be labeled `const`. For return parameters
other than STL containers, use a pointer.
* {DO} avoid use of default arguments.
* {DONT} use C++ exceptions, they are disabled in the builds and not caught.
* {DO} use nullptr (instead of 0 or NULL) for pointers.
* {DO} use size\_t for loop iterators and size values.
* {DO} use uint8\_t pointers instead of void pointers to denote binary data.
* {DO} use C++11 according to the [Chromium guide on C++11]
(http://chromium-cpp.appspot.com/).
### [Naming](https://google.github.io/styleguide/cppguide.html#Naming)
#### File Names
* {DEV} Filenames should be all lowercase and can include underscores (`_`).
If the file is an implementation of a class, the filename may be capitalized
the same as the major class.
* {DEV} We use .cpp (instead of .cc), .h and .inl (inlined files) for C++
files and headers.
#### Directory Names
* Directory names should be all lowercase, unless following an externally
imposed capitalization (eg include/EGL, or src/libGLESv2, etc)
#### Variable Names
Use the following guidelines, they do deviate somewhat from the Google
guidelines.
* class and type names: start with capital letter and use CamelCase.
* {DEV} class member variables: use an **`m`** prefix instead of trailing
underscore and use CamelCase.
* global variables (if they must be used): use a **`g_`** prefix.
* {DEV} variable names: start with lower case and use CamelCase (chosen for consistency)
* {DEV} function names: Member functions start with lower case and use CamelCase. Non-member functions start with capital letter and
use CamelCase (chosen for consistency)
* Constants: start with a **`k`** and use CamelCase
* namespaces: use all lower case
* Enum Names - use class enums, and the values should be uppercase with underscores.
* macros: all uppercase with underscores
* exceptions to naming: use common sense!
### [Comments](https://google.github.io/styleguide/cppguide.html#Comments)
* {DO} read and follow Google's recommendations.
* Each file **must** start with the following boilerplate notice:
```
//
// Copyright (c) 2016 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
```
### [Formatting](https://google.github.io/styleguide/cppguide.html#Formatting)
* {DEV} Avoid excessively long lines. Please keep lines under 100 columns
long.
* Use unix-style newlines.
* {DO} use only spaces. No tab characters. Configure your editor to emit
spaces when you hit the TAB-key.
* {DEV} indent 4 spaces at a time.
* conditionals: place space outside the parenthesis. No spaces inside.
* switch statements: use the output of `git cl format`.
* class format(eg private, public, protected): indent by 2 spaces. Regular
4-space indent from the outer scope for declarations/definitions.
* pointers and references: **`*`** and **`&`** tight against the variable
* namespaces: are not indented.
* extern code blocks: are not indented.
* {DEV} braces should go on a separate line, except for functions defined in a
header file where the whole function declaration and definition fit on one
line.
Examples:
```
if (conditional)
{
stuff();
}
else
{
otherstuff()
}
```
```
switch (conditional)
{
case foo:
dostuff();
break;
case bar:
otherstuff();
break;
default:
WTFBBQ();
}
```
```
class MyClass : public Foo
{
public:
MyClass();
~MyClass() {};
private:
DISALLOW_COPY_AND_ASSIGN(MyClass);
};
```
```
char *c;
const string &str;
```
### [Exceptions to the Rules](https://google.github.io/styleguide/cppguide.html#Exceptions_to_the_Rules)
* If modifying pre-existing code that does not match the standard, the altered
portions of the code should be changed to match the standard.