Vim source code
Here are a few hints for finding your way around the source code. This doesn't make it less complex than it is, but it gets you started.
You might also want to read
First of all, use
:make tags to generate a tags file, so that you can jump
around in the source code.
To jump to a function or variable definition, move the cursor on the name and
CTRL-] command. Use
CTRL-O to jump back.
To jump to a file, move the cursor on its name and use the
Most code can be found in a file with an obvious name (incomplete list):
|arglist.c||handling argument list|
|blob.c||blob data type|
|buffer.c||manipulating buffers (loaded files)|
|bufwrite.c||writing a buffer to file|
|change.c||handling changes to text|
|debugger.c||vim script debugger|
|diff.c||diff mode (vimdiff)|
|drawline.c||drawing a window line|
|drawscreen.c||drawing the windows|
|evalbuffer.c||buffer related built-in functions|
|evalwindow.c||window related built-in functions|
|fileio.c||reading and writing files|
|filepath.c||dealing with file names and paths|
|findfile.c||search for files in 'path'|
|getchar.c||getting characters and key mapping|
|indent.c||C and Lisp indentation|
|insexpand.c||Insert mode completion|
|map.c||mapping and abbreviations|
|mbyte.c||multi-byte character handling|
|memfile.c||storing lines for buffers in a swapfile|
|memline.c||storing lines for buffers in memory|
|mouse.c||handling the mouse|
|ops.c||handling operators ("d", "y", "p")|
|optionstr.c||handling string options|
|profiler.c||vim script profiler|
|quickfix.c||quickfix commands (":make", ":cn")|
|scriptfile.c||runtime directory handling and sourcing scripts|
|screen.c||lower level screen functions|
|session.c||sessions and views|
|spell.c||spell checking core|
|spellfile.c||spell file handling|
|spellsuggest.c||spell correction suggestions|
|syntax.c||syntax and other highlighting|
|term.c||terminal handling, termcap codes|
|testing.c||testing: assert and test functions|
|undo.c||undo and redo|
|usercmd.c||user defined commands|
|userfunc.c||user defined functions|
|window.c||handling split windows|
If you have a reasonable recent version of gdb, you can use the
command to debug Vim. See
When something is time critical or stepping through code is a hassle, use the channel logging to create a time-stamped log file. Add lines to the code like this:
ch_log(NULL, "Value is now %02x", value);
After compiling and starting Vim, do:
:call ch_logfile('debuglog', 'w')
debuglog to see what happens. The channel functions already have
ch_log() calls, thus you always see that in the log.
The current mode is stored in
State. The values it can have are
CMDLINE, and a few others.
The current window is
curwin. The current buffer is
curbuf. These point
to structures with the cursor position in the window, option values, the file
name, etc. These are defined in
All the global variables are declared in
The main loop
This is conveniently called
main_loop(). It updates a few things and then
normal_cmd() to process a command. This returns when the command is
The basic idea is that Vim waits for the user to type a character and
processes it until another character is needed. Thus there are several places
where Vim waits for a character to be typed. The
vgetc() function is used
for this. It also handles mapping.
Updating the screen is mostly postponed until a command or a sequence of
commands has finished. The work is done by
update_screen(), which calls
win_update() for every window, which calls
win_line() for every line.
See the start of
for more explanations.
When typing a
normal_cmd() will call
getcmdline() to obtain a line
with an Ex command.
getcmdline() contains a loop that will handle each typed
character. It returns when hitting
Esc or some other character that
ends the command line mode.
Ex commands are handled by the function
do_cmdline(). It does the generic
parsing of the
: command line and calls
do_one_cmd() for each separate
command. It also takes care of while loops.
do_one_cmd() parses the range and generic arguments and puts them in the
exarg_t and passes it to the function that handles the command.
: commands are listed in
ex_cmds.h. The third entry of each item is
the name of the function that handles the command. The last entry are the
flags that are used for the command.
Normal mode commands
The Normal mode commands are handled by the
normal_cmd() function. It also
handles the optional count and an extra character for some commands. These
are passed in a
cmdarg_t to the function that handles the command.
There is a table
which lists the first character of every command. The second entry of each
item is the name of the function that handles the command.
Insert mode commands
When doing an
normal_cmd() will call the
function. It contains a loop that waits for the next character and handles it.
It returns when leaving Insert mode.
There is a list with all option names in
Most of the GUI code is implemented like it was a clever terminal. Typing a
character, moving a scrollbar, clicking the mouse, etc. are all translated
into events which are written in the input buffer. These are read by the
main code, just like reading from a terminal. The code for this is scattered
gui_send_mouse_event() for a mouse click and
a menu action. Key hits are handled by the system-specific GUI code, which
add_to_input_buf() to send the key code.
Updating the GUI window is done by writing codes in the output buffer, just
like writing to a terminal. When the buffer gets full or is flushed,
gui_write() will parse the codes and draw the appropriate items. Finally the
system-specific GUI code will be called to do the work.
Debugging the GUI
Remember to prevent that gvim forks and the debugger thinks Vim has exited,
-f argument. In gdb:
run -f -g.
When stepping through display updating code, the focus event is triggered
when going from the debugger to Vim and back. To avoid this, recompile with
some code in
If you would like to help making Vim better, see the
README.md for version 8.1 of the Vim source code.