LibFormat

LibFormat is a library that implements automatic source code formatting based on Clang. This documents describes the LibFormat interface and design as well as some basic style discussions.

If you just want to use clang-format as a tool or integrated into an editor, checkout ClangFormat.

Design

FIXME: Write up design.

Interface

The core routine of LibFormat is reformat():

tooling::Replacements reformat(const FormatStyle &Style, Lexer &Lex,
                               SourceManager &SourceMgr,
                               std::vector<CharSourceRange> Ranges);

This reads a token stream out of the lexer Lex and reformats all the code ranges in Ranges. The FormatStyle controls basic decisions made during formatting. A list of options can be found under Style Options.

The style options are described in Clang-Format Style Options.

Style Options

The style options describe specific formatting options that can be used in order to make ClangFormat comply with different style guides. Currently, several style guides are hard-coded:

/// Returns a format style complying with the LLVM coding standards:
/// https://llvm.org/docs/CodingStandards.html.
FormatStyle getLLVMStyle();

/// Returns a format style complying with Google's C++ style guide:
/// http://google-styleguide.googlecode.com/svn/trunk/cppguide.xml.
FormatStyle getGoogleStyle();

/// Returns a format style complying with Chromium's style guide:
/// https://chromium.googlesource.com/chromium/src/+/refs/heads/main/styleguide/styleguide.md
FormatStyle getChromiumStyle();

/// Returns a format style complying with the GNU coding standards:
/// https://www.gnu.org/prep/standards/standards.html
FormatStyle getGNUStyle();

/// Returns a format style complying with Mozilla's style guide
/// https://firefox-source-docs.mozilla.org/code-quality/coding-style/index.html
FormatStyle getMozillaStyle();

/// Returns a format style complying with Webkit's style guide:
/// https://webkit.org/code-style-guidelines/
FormatStyle getWebkitStyle();

/// Returns a format style complying with Microsoft's style guide:
/// https://docs.microsoft.com/en-us/visualstudio/ide/editorconfig-code-style-settings-reference
FormatStyle getMicrosoftStyle();

These options are also exposed in the standalone tools through the -style option.

In the future, we plan on making this configurable.