refactor(options): reduce `findoption()` usage

Problem: Many places in the code use `findoption()` to access an option using its name, even if the option index is available. This is very slow because it requires looping through the options array over and over.

Solution: Use option index instead of name wherever possible. Also introduce an `OptIndex` enum which contains the index for every option as enum constants, this eliminates the need to pass static option names as strings.

1 files changed, 5 insertions, 5 deletions

diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 68c316fde0..786612070e 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -4265,7 +4265,7 @@ skip:
   // Show 'inccommand' preview if there are matched lines.
   if (cmdpreview_ns > 0 && !aborting()) {
     if (got_quit || profile_passed_limit(timeout)) {  // Too slow, disable.
-      set_string_option_direct("icm", -1, "", OPT_FREE, SID_NONE);
+      set_string_option_direct(kOptInccommand, "", OPT_FREE, SID_NONE);
     } else if (*p_icm != NUL && pat != NULL) {
       if (pre_hl_id == 0) {
         pre_hl_id = syn_check_group(S_LEN("Substitute"));
@@ -4544,8 +4544,8 @@ bool prepare_tagpreview(bool undo_sync)
   curwin->w_p_wfh = true;
   RESET_BINDING(curwin);                // don't take over 'scrollbind' and 'cursorbind'
   curwin->w_p_diff = false;             // no 'diff'
-  set_string_option_direct("fdc", -1,     // no 'foldcolumn'
-                           "0", OPT_FREE, SID_NONE);
+
+  set_string_option_direct(kOptFoldcolumn, "0", OPT_FREE, SID_NONE);  // no 'foldcolumn'
   return true;
 }
 
@@ -4564,7 +4564,7 @@ static int show_sub(exarg_T *eap, pos_T old_cusr, PreviewLines *preview_lines, i
   buf_T *cmdpreview_buf = NULL;
 
   // disable file info message
-  set_string_option_direct("shm", -1, "F", OPT_FREE, SID_NONE);
+  set_string_option_direct(kOptShortmess, "F", OPT_FREE, SID_NONE);
 
   // Update the topline to ensure that main window is on the correct line
   update_topline(curwin);
@@ -4665,7 +4665,7 @@ static int show_sub(exarg_T *eap, pos_T old_cusr, PreviewLines *preview_lines, i
 
   xfree(str);
 
-  set_string_option_direct("shm", -1, save_shm_p, OPT_FREE, SID_NONE);
+  set_string_option_direct(kOptShortmess, save_shm_p, OPT_FREE, SID_NONE);
   xfree(save_shm_p);
 
   return preview ? 2 : 1;