add a quick note on coding style

Author: Bulat Shakirzyanov

.clang-format

@@ -0,0 +1,40 @@
+BasedOnStyle: LLVM
+AlignAfterOpenBracket: true
+AlignConsecutiveAssignments: true
+AlignEscapedNewlinesLeft: true
+AlignOperands: true
+AlignTrailingComments: true
+AllowAllParametersOfDeclarationOnNextLine: true
+AllowShortBlocksOnASingleLine: false
+AllowShortCaseLabelsOnASingleLine: false
+AllowShortFunctionsOnASingleLine: false
+AllowShortIfStatementsOnASingleLine: false
+AllowShortLoopsOnASingleLine: false
+AlwaysBreakAfterDefinitionReturnType: true
+AlwaysBreakBeforeMultilineStrings: true
+BinPackArguments: true
+BinPackParameters: false
+BreakBeforeBinaryOperators: NonAssignment
+BreakBeforeBraces: Linux
+BreakBeforeTernaryOperators: false
+BreakConstructorInitializersBeforeComma: true
+ColumnLimit: 0
+ContinuationIndentWidth: 2
+Cpp11BracedListStyle: false
+DerivePointerAlignment: false
+IndentCaseLabels: false
+IndentWidth: 2
+IndentWrappedFunctionNames: false
+KeepEmptyLinesAtTheStartOfBlocks: false
+MaxEmptyLinesToKeep: 1
+PointerAlignment: Left
+SpaceAfterCStyleCast: true
+SpaceBeforeAssignmentOperators: true
+SpaceBeforeParens: ControlStatements
+SpaceInEmptyParentheses: false
+SpacesBeforeTrailingComments: 1
+SpacesInCStyleCastParentheses: false
+SpacesInContainerLiterals: false
+SpacesInParentheses: false
+TabWidth: 2
+UseTab: Never

CONTRIBUTING.md

@@ -13,8 +13,24 @@ help the maintainer to fix the bug that you've discovered quicker:
 * Write a failing test. The PHP Driver uses [PHPUnit test framework](https://phpunit.de/). A reliably
   failing test is the fastest way to demonstrate and fix a problem.
 
-## Pull Requests
+## Pull requests
 
 If you're able to fix a bug yourself, you can [fork the repository](https://help.github.com/articles/fork-a-repo/) and [submit a pull request](https://help.github.com/articles/using-pull-requests/) with the fix.
 
 To protect DataStax and the community, all contributors are required to [sign the DataStax Contribution License Agreement](http://cla.datastax.com/). The process is completely electronic and should only take a few minutes.
+
+## Style guide
+
+There are 2 distinct coding styles used in the repository. Depending on which part of the codebase you're going to touch, you need to follow one or the other.
+
+### PHP coding style
+
+The API stubs provided by the extension are following [the Symfony 2 coding standard](http://symfony.com/doc/current/contributing/code/standards.html). The only exception are empty method stubs, those have opening and closing brace following the closing parenthesis on the same line.
+
+### C coding style
+
+The main difference here is the spacing, the C code uses 2 spaces for indendation, while the PHP code - 4. For your convenience, a `.clang-format` file is available in the repository's root directory. Using `clang-format`, you can format source files to match the coding style almost completely:
+
+```bash
+clang-format -style=file -i ext/php_cassandra.c
+```