10.5.3 Indentation

Standard GNU coding style is used.

Indenting files with fixcc.py (recommended)

LilyPond provides a python script that will adjust the indentation and spacing on a .cc or .hh file to very near the GNU standard:

scripts/auxiliar/fixcc.py FILENAME

This can be run on all files at once, but this is not recommended for normal contributors or developers.

scripts/auxiliar/fixcc.py \
  $(find flower lily -name '*cc' -o -name '*hh' | grep -v /out)

Indenting with emacs

The following hooks will produce indentation which is similar to our official indentation as produced with fixcc.py.

(add-hook 'c++-mode-hook
     '(lambda ()
        (c-set-style "gnu")
        (setq indent-tabs-mode nil))

If you like using font-lock, you can also add this to your ‘.emacs’:

(setq font-lock-maximum-decoration t)
(setq c++-font-lock-keywords-3
      (append
       c++-font-lock-keywords-3
       '(("\\b\\(a-zA-Z_?+_\\)\\b" 1 font-lock-variable-name-face) ("\\b\\(A-Z?+a-z_?+\\)\\b" 1 font-lock-type-face))
       ))

Indenting with vim

Although emacs indentation is the GNU standard, correct indentation for C++ files can be achieved by using the settings recommended in the GNU GCC Wiki. Save the following in ‘~/.vim/after/ftplugin/cpp.vim’:

setlocal cindent
setlocal cinoptions=>4,n-2,{2,^-2,:2,=2,g0,h2,p5,t0,+2,(0,u0,w1,m1
setlocal shiftwidth=2
setlocal softtabstop=2
setlocal textwidth=79
setlocal fo-=ro fo+=cql
" use spaces instead of tabs
setlocal expandtab
" remove trailing whitespace on write
autocmd BufWritePre * :%s/\s\+$//e

With these settings, files can be reindented automatically by highlighting the lines to be indented in visual mode (use V to enter visual mode) and pressing =, or a single line correctly indented in normal mode by pressing ==.

A ‘scheme.vim’ file will help improve the indentation of Scheme code. This one was suggested by Patrick McCarty. It should be saved in ‘~/.vim/after/syntax/scheme.vim’.

" Additional Guile-specific 'forms'
syn keyword schemeSyntax define-public define*-public
syn keyword schemeSyntax define* lambda* let-keywords*
syn keyword schemeSyntax defmacro defmacro* define-macro
syn keyword schemeSyntax defmacro-public defmacro*-public
syn keyword schemeSyntax use-modules define-module
syn keyword schemeSyntax define-method define-class

" Additional LilyPond-specific 'forms'
syn keyword schemeSyntax define-markup-command define-markup-list-command
syn keyword schemeSyntax define-safe-public define-music-function
syn keyword schemeSyntax def-grace-function

" All of the above should influence indenting too
setlocal lw+=define-public,define*-public
setlocal lw+=define*,lambda*,let-keywords*
setlocal lw+=defmacro,defmacro*,define-macro
setlocal lw+=defmacro-public,defmacro*-public
setlocal lw+=use-modules,define-module
setlocal lw+=define-method,define-class
setlocal lw+=define-markup-command,define-markup-list-command
setlocal lw+=define-safe-public,define-music-function
setlocal lw+=def-grace-function

" These forms should not influence indenting
setlocal lw-=if
setlocal lw-=set!

" Try to highlight all ly: procedures
syn match schemeFunc "ly:[^) ]\+"

For documentation work on texinfo files, identify the file extensions used as texinfo files in your ‘.vim/filetype.vim’:

if exists("did_load_filetypes")
  finish
endif
augroup filetypedetect
  au! BufRead,BufNewFile *.itely setfiletype texinfo
  au! BufRead,BufNewFile *.itexi setfiletype texinfo
  au! BufRead,BufNewFile *.tely  setfiletype texinfo
augroup END

and add these settings in ‘.vim/after/ftplugin/texinfo.vim’:

setlocal expandtab
setlocal shiftwidth=2
setlocal textwidth=66

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LilyPond — Contributor’s Guide v2.21.0 (development-branch).