FakeVim is library to emulate Vim in QTextEdit, QPlainTextEdit and possibly other Qt widgets.

To build the library and simple example editor (in test directory), run following commands.

qmake
make

Most of supported commands can be followed by motion command or executed in visual mode, work with registers or can be prefixed with number of repetitions.

Here is list of emulated commands with description where it can diverge from Vim in functionality.

• normal
• insert and replace
• visual
• command line (:)

• basic movement -- h/j/k/l, <C-U>, <C-D>, <C-F>, <C-B>, gg, G, 0, ^, $ etc.
• word movement -- w, e, b etc.
• "inner/a" movement -- ciw, 3daw, ya{ etc.
• f, t movement
• [, ] movement
• {, } -- paragraph movement
• delete/change/yank/paste with register
• undo/redo
• <C-A>, <C-X> -- increase or decrease number in decimal/octal/hexadecimal format (e.g. 128<C-A> on or before "0x0ff" changes it to "0x17f")
• . -- repeat last change
• /search, ?search, *, #, n, N -- most of regular expression syntax used in Vim except \< and \> just is the same as \b in QRegExp
• @, q (macro recording, execution) -- special keys are saved as <S-Left>
• marks
• gv -- last visual selection; can differ if text is edited around it
• indentation -- =, <<, >> etc. with movement, count and in visual mode
• "to upper/lower" -- ~, gU, gu etc.
• i, a, o, I, A, O -- enter insert mode
• scroll window -- zt, zb, zz etc.
• wrap line movement -- gj, gk, g0, g^, g$

• :map, :unmap, :inoremap etc.
• :source -- very basic line-by-line sourcing of vimrc files
• :substitute -- substitute expression in range
• :'<,'>!cmd -- filter through an external command (e.g. sort lines in file with :%!sort)
• :.!cmd -- insert standard output of an external command
• :read
• :yank, :delete, :change
• :move, :join
• :20 -- go to address
• :history
• :registers, :display
• :nohlsearch
• :undo, :redo
• :normal
• :<, :>

• <C-O> -- execute single command and return to insert mode
• <C-V> -- insert raw character
• <insert> -- toggle replace mode

• autoindent
• clipboard
• backspace
• expandtab
• hlsearch
• ignorecase
• incsearch
• indent
• iskeyword
• scrolloff
• shiftwidth
• showcmd
• smartcase
• smartindent
• smarttab
• startofline
• tabstop
• tildeop
• wrapscan

" highlight matched
set hlsearch
" case insensitive search
set ignorecase
set smartcase
" search while typing
set incsearch
" wrap-around when searching
set wrapscan
" show pressed keys in lower right corner
set showcmd
" tab -> spaces
set expandtab
set tabstop=4
set shiftwidth=4
" keep a 5 line buffer for the cursor from top/bottom of window
set scrolloff=5
" X11 clipboard
set clipboard=unnamed
" use ~ with movement
set tildeop

" mappings
nnoremap ; :
inoremap jj <Esc>

" clear highlighted search term on space
noremap <silent> <Space> :nohls<CR>

" reselect visual block after indent
vnoremap < <gv
vnoremap > >gv

" MOVE LINE/BLOCK
nnoremap <C-S-J> :m+<CR>==
nnoremap <C-S-K> :m-2<CR>==
inoremap <C-S-J> <Esc>:m+<CR>==gi
inoremap <C-S-K> <Esc>:m-2<CR>==gi
vnoremap <C-S-J> :m'>+<CR>gv=gv
vnoremap <C-S-K> :m-2<CR>gv=gv

There are appropriate signals emitted for command which has to be processed by the underlying editor widget (folds, windows, tabs, command line, messages etc.). See example in test/ directory or implementation of FakeVim plugin in Qt Creator IDE.