vim-patch:9.0.1958: cannot complete option values

Problem:  cannot complete option values
Solution: Add completion functions for several options

Add cmdline tab-completion for setting string options

Add tab-completion for setting string options on the cmdline using
`:set=` (along with `:set+=` and `:set-=`).

The existing tab completion for setting options currently only works
when nothing is typed yet, and it only fills in with the existing value,
e.g. when the user does `:set diffopt=<Tab>` it will be completed to
`set diffopt=internal,filler,closeoff` and nothing else. This isn't too
useful as a user usually wants auto-complete to suggest all the possible
values, such as 'iblank', or 'algorithm:patience'.

For set= and set+=, this adds a new optional callback function for each
option that can be invoked when doing completion. This allows for each
option to have control over how completion works. For example, in
'diffopt', it will suggest the default enumeration, but if `algorithm:`
is selected, it will further suggest different algorithm types like
'meyers' and 'patience'. When using set=, the existing option value will
be filled in as the first choice to preserve the existing behavior. When
using set+= this won't happen as it doesn't make sense.

For flag list options (e.g. 'mouse' and 'guioptions'), completion will
take into account existing typed values (and in the case of set+=, the
existing option value) to make sure it doesn't suggest duplicates.

For set-=, there is a new `ExpandSettingSubtract` function which will
handle flag list and comma-separated options smartly, by only suggesting
values that currently exist in the option.

Note that Vim has some existing code that adds special handling for
'filetype', 'syntax', and misc dir options like 'backupdir'. This change
preserves them as they already work, instead of converting to the new
callback API for each option.

closes: vim/vim#13182

https://github.com/vim/vim/commit/900894b09a95398dfc75599e9f0aa2ea25723384

Co-authored-by: Yee Cheng Chin <ychin.git@gmail.com>

1 files changed, 11 insertions, 10 deletions

diff --git a/src/nvim/cmdexpand.c b/src/nvim/cmdexpand.c
index d733ffe6ab..3969162b6e 100644
--- a/src/nvim/cmdexpand.c
+++ b/src/nvim/cmdexpand.c
@@ -69,9 +69,6 @@
 #include "nvim/vim.h"
 #include "nvim/window.h"
 
-/// Type used by ExpandGeneric()
-typedef char *(*CompleteListItemGetter)(expand_T *, int);
-
 /// Type used by call_user_expand_func
 typedef void *(*user_expand_func_T)(const char *, int, typval_T *);
 
@@ -107,6 +104,8 @@ static bool cmdline_fuzzy_completion_supported(const expand_T *const xp)
          && xp->xp_context != EXPAND_HELP
          && xp->xp_context != EXPAND_LUA
          && xp->xp_context != EXPAND_OLD_SETTING
+         && xp->xp_context != EXPAND_STRING_SETTING
+         && xp->xp_context != EXPAND_SETTING_SUBTRACT
          && xp->xp_context != EXPAND_OWNSYNTAX
          && xp->xp_context != EXPAND_PACKADD
          && xp->xp_context != EXPAND_RUNTIME
@@ -2694,8 +2693,7 @@ static int ExpandFromContext(expand_T *xp, char *pat, char ***matches, int *numM
     return OK;
   }
   if (xp->xp_context == EXPAND_OLD_SETTING) {
-    ExpandOldSetting(numMatches, matches);
-    return OK;
+    return ExpandOldSetting(numMatches, matches);
   }
   if (xp->xp_context == EXPAND_BUFFERS) {
     return ExpandBufnames(pat, numMatches, matches, options);
@@ -2765,6 +2763,10 @@ static int ExpandFromContext(expand_T *xp, char *pat, char ***matches, int *numM
   if (xp->xp_context == EXPAND_SETTINGS
       || xp->xp_context == EXPAND_BOOL_SETTINGS) {
     ret = ExpandSettings(xp, &regmatch, pat, numMatches, matches, fuzzy);
+  } else if (xp->xp_context == EXPAND_STRING_SETTING) {
+    ret = ExpandStringSetting(xp, &regmatch, numMatches, matches);
+  } else if (xp->xp_context == EXPAND_SETTING_SUBTRACT) {
+    ret = ExpandSettingSubtract(xp, &regmatch, numMatches, matches);
   } else if (xp->xp_context == EXPAND_MAPPINGS) {
     ret = ExpandMappings(pat, &regmatch, numMatches, matches);
   } else if (xp->xp_context == EXPAND_USER_DEFINED) {
@@ -2788,9 +2790,8 @@ static int ExpandFromContext(expand_T *xp, char *pat, char ***matches, int *numM
 /// program.  Matching strings are copied into an array, which is returned.
 ///
 /// @param func  returns a string from the list
-static void ExpandGeneric(const char *const pat, expand_T *xp, regmatch_T *regmatch,
-                          char ***matches, int *numMatches, CompleteListItemGetter func,
-                          int escaped)
+void ExpandGeneric(const char *const pat, expand_T *xp, regmatch_T *regmatch, char ***matches,
+                   int *numMatches, CompleteListItemGetter func, bool escaped)
 {
   const bool fuzzy = cmdline_fuzzy_complete(pat);
   *matches = NULL;
@@ -2863,6 +2864,7 @@ static void ExpandGeneric(const char *const pat, expand_T *xp, regmatch_T *regma
   // in the specified order.
   const bool sort_matches = !fuzzy
                             && xp->xp_context != EXPAND_MENUNAMES
+                            && xp->xp_context != EXPAND_STRING_SETTING
                             && xp->xp_context != EXPAND_MENUS
                             && xp->xp_context != EXPAND_SCRIPTNAMES;
 
@@ -3221,8 +3223,7 @@ void globpath(char *path, char *file, garray_T *ga, int expand_options, bool dir
 
       char **p;
       int num_p = 0;
-      (void)ExpandFromContext(&xpc, buf, &p, &num_p,
-                              WILD_SILENT | expand_options);
+      (void)ExpandFromContext(&xpc, buf, &p, &num_p, WILD_SILENT | expand_options);
       if (num_p > 0) {
         ExpandEscape(&xpc, buf, num_p, p, WILD_SILENT | expand_options);