'inccommand': Introduce CMDPREVIEW state.

Command "live preview" is fundamentally a non-recursive concept
("preview of a preview" is not useful). Maintaining this as a
global is less awkward and closer to what we actually want to
express, vs adorning exarg_T, CommandLineState, etc.

7 files changed, 38 insertions, 37 deletions

diff --git a/src/nvim/ex_cmds.c b/src/nvim/ex_cmds.c
index 40e506e80e..42af5989a1 100644
--- a/src/nvim/ex_cmds.c
+++ b/src/nvim/ex_cmds.c
@@ -2952,10 +2952,11 @@ void sub_set_replacement(SubReplacementString sub)
 /// @param[in]  pat  Search pattern
 /// @param[in]  sub  Replacement string
 /// @param[in]  cmd  Command from :s_flags
+/// @param[in]  save Save pattern to options, history
 ///
 /// @returns true if :substitute can be replaced with a join command
-static bool sub_joining_lines(exarg_T *eap, char_u *pat,
-                              char_u *sub, char_u *cmd)
+static bool sub_joining_lines(exarg_T *eap, char_u *pat, char_u *sub,
+                              char_u *cmd, bool save)
   FUNC_ATTR_NONNULL_ARG(1, 3, 4)
 {
   // TODO(vim): find a generic solution to make line-joining operations more
@@ -2989,7 +2990,7 @@ static bool sub_joining_lines(exarg_T *eap, char_u *pat,
       ex_may_print(eap);
     }
 
-    if (!eap->is_live) {
+    if (save) {
       if (!cmdmod.keeppatterns) {
         save_re_pat(RE_SUBST, pat, p_magic);
       }
@@ -3108,7 +3109,7 @@ static char_u *sub_parse_flags(char_u *cmd, subflags_T *subflags,
 /// The usual escapes are supported as described in the regexp docs.
 ///
 /// @return buffer used for 'inccommand' preview
-static buf_T *do_sub(exarg_T *eap)
+static buf_T *do_sub(exarg_T *eap, proftime_T timeout)
 {
   long i = 0;
   regmmatch_T regmatch;
@@ -3137,10 +3138,10 @@ static buf_T *do_sub(exarg_T *eap)
   bool endcolumn = false;   // cursor in last column when done
   MatchedLineVec matched_lines = KV_INITIAL_VALUE;
   pos_T old_cursor = curwin->w_cursor;
-  proftime_T timeout = eap->is_live ? profile_setlimit(p_rdt) : profile_zero();
   int start_nsubs;
   int save_ma = 0;
   int save_b_changed = curbuf->b_changed;
+  bool preview = (State & CMDPREVIEW);
 
   if (!global_busy) {
     sub_nsubs = 0;
@@ -3208,7 +3209,7 @@ static buf_T *do_sub(exarg_T *eap)
       mb_ptr_adv(cmd);
     }
 
-    if (!eap->skip && !eap->is_live) {
+    if (!eap->skip && !preview) {
       sub_set_replacement((SubReplacementString) {
         .sub = xstrdup((char *) sub),
         .timestamp = os_time(),
@@ -3228,7 +3229,7 @@ static buf_T *do_sub(exarg_T *eap)
     endcolumn = (curwin->w_curswant == MAXCOL);
   }
 
-  if (sub_joining_lines(eap, pat, sub, cmd)) {
+  if (sub_joining_lines(eap, pat, sub, cmd, !preview)) {
     return NULL;
   }
 
@@ -3273,7 +3274,7 @@ static buf_T *do_sub(exarg_T *eap)
     return NULL;
   }
 
-  if (search_regcomp(pat, RE_SUBST, which_pat, (eap->is_live ? 0 : SEARCH_HIS),
+  if (search_regcomp(pat, RE_SUBST, which_pat, (preview ? 0 : SEARCH_HIS),
                      &regmatch) == FAIL) {
     if (subflags.do_error) {
       EMSG(_(e_invcmd));
@@ -3403,7 +3404,7 @@ static buf_T *do_sub(exarg_T *eap)
         curwin->w_cursor.lnum = lnum;
         do_again = FALSE;
 
-        if (eap->is_live) {
+        if (preview) {
           // Increment the in-line match count and store the column.
           matched_line.nmatch++;
           kv_push(matched_line.cols, regmatch.startpos[0].col);
@@ -3456,7 +3457,7 @@ static buf_T *do_sub(exarg_T *eap)
             goto skip;
         }
 
-        if (subflags.do_ask && !eap->is_live) {
+        if (subflags.do_ask && !preview) {
           int typed = 0;
 
           /* change State to CONFIRM, so that the mouse works
@@ -3627,9 +3628,9 @@ static buf_T *do_sub(exarg_T *eap)
          * use "\=col("."). */
         curwin->w_cursor.col = regmatch.startpos[0].col;
 
-        // 3. Substitute the string. During 'inccommand' only do this if there
-        //    is a replace pattern.
-        if (!eap->is_live || has_second_delim) {
+        // 3. Substitute the string. During 'inccommand' preview only do this if
+        //    there is a replace pattern.
+        if (!preview || has_second_delim) {
           if (subflags.do_count) {
             // prevent accidentally changing the buffer by a function
             save_ma = curbuf->b_p_ma;
@@ -3873,7 +3874,7 @@ skip:
       xfree(sub_firstline);          /* free the copy of the original line */
       sub_firstline = NULL;
 
-      if (eap->is_live) {
+      if (preview) {
         matched_line.lnum = lnum;
         matched_line.line = vim_strsave(ml_get(lnum));
         kv_push(matched_lines, matched_line);
@@ -3917,7 +3918,7 @@ skip:
           beginline(BL_WHITE | BL_FIX);
         }
       }
-      if (!eap->is_live && !do_sub_msg(subflags.do_count) && subflags.do_ask) {
+      if (!preview && !do_sub_msg(subflags.do_count) && subflags.do_ask) {
         MSG("");
       }
     } else {
@@ -3952,7 +3953,7 @@ skip:
 
   // Show 'inccommand' preview if there are matched lines.
   buf_T *preview_buf = NULL;
-  if (eap->is_live && !aborting()) {
+  if (preview && !aborting()) {
     if (got_quit) {  // Substitution is too slow, disable 'inccommand'.
       set_string_option_direct((char_u *)"icm", -1, (char_u *)"", OPT_FREE,
                                SID_NONE);
@@ -6122,8 +6123,9 @@ static buf_T *show_sub(exarg_T *eap, pos_T old_cusr, char_u *pat, char_u *sub,
 /// from undo history.
 void ex_substitute(exarg_T *eap)
 {
-  if (*p_icm == NUL || !eap->is_live) {  // 'inccommand' is disabled
-    (void)do_sub(eap);
+  bool preview = (State & CMDPREVIEW);
+  if (*p_icm == NUL || !preview) {  // 'inccommand' is disabled
+    (void)do_sub(eap, profile_zero());
     return;
   }
 
@@ -6145,7 +6147,7 @@ void ex_substitute(exarg_T *eap)
   curwin->w_p_cul = false;    // Disable 'cursorline'
   curwin->w_p_cuc = false;    // Disable 'cursorcolumn'
 
-  buf_T *preview_buf = do_sub(eap);
+  buf_T *preview_buf = do_sub(eap, profile_setlimit(p_rdt));
 
   if (save_changedtick != curbuf->b_changedtick) {
     // Undo invisibly. This also moves the cursor!
diff --git a/src/nvim/ex_cmds_defs.h b/src/nvim/ex_cmds_defs.h
index 8a2ebe2cd4..8148eb5cee 100644
--- a/src/nvim/ex_cmds_defs.h
+++ b/src/nvim/ex_cmds_defs.h
@@ -124,7 +124,6 @@ struct exarg {
   LineGetter getline;           ///< Function used to get the next line
   void   *cookie;               ///< argument for getline()
   struct condstack *cstack;     ///< condition stack for ":if" etc.
-  bool is_live;                 ///< 'inccommand' live preview
 };
 
 #define FORCE_BIN 1             // ":edit ++bin file"
diff --git a/src/nvim/ex_docmd.c b/src/nvim/ex_docmd.c
index 07e0fa8844..76dddf874d 100644
--- a/src/nvim/ex_docmd.c
+++ b/src/nvim/ex_docmd.c
@@ -1248,7 +1248,6 @@ static char_u * do_one_cmd(char_u **cmdlinep,
   memset(&ea, 0, sizeof(ea));
   ea.line1 = 1;
   ea.line2 = 1;
-  ea.is_live = flags & DOCMD_LIVE;
   ex_nesting_level++;
 
   /* When the last file has not been edited :q has to be typed twice. */
@@ -9648,12 +9647,12 @@ static void ex_terminal(exarg_T *eap)
   }
 }
 
-/// Check whether commandline starts with a live command
+/// Checks if `cmd` is "previewable" (i.e. supported by 'inccommand').
 ///
 /// @param[in] cmd Commandline to check. May start with a range.
 ///
-/// @return True if first command is a live command
-bool cmd_is_live(char_u *cmd)
+/// @return true if `cmd` is previewable
+bool cmd_can_preview(char_u *cmd)
 {
   if (cmd == NULL) {
     return false;
diff --git a/src/nvim/ex_docmd.h b/src/nvim/ex_docmd.h
index 84f1a13a15..fb6aac223f 100644
--- a/src/nvim/ex_docmd.h
+++ b/src/nvim/ex_docmd.h
@@ -10,7 +10,6 @@
 #define DOCMD_KEYTYPED  0x08      // don't reset KeyTyped
 #define DOCMD_EXCRESET  0x10      // reset exception environment (for debugging
 #define DOCMD_KEEPLINE  0x20      // keep typed line for repeating with "."
-#define DOCMD_LIVE      0x40      // show updates as-you-type ("live" command)
 
 /* defines for eval_vars() */
 #define VALID_PATH              1
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 3093caebaf..532775ad0b 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -103,7 +103,6 @@ typedef struct command_line_state {
   linenr_T  old_botline;
   int did_incsearch;
   int incsearch_postponed;
-  bool live;                            // performing 'inccommand' preview
   int did_wild_list;                    // did wild_list() recently
   int wim_index;                        // index in wim_flags[]
   int res;
@@ -400,8 +399,7 @@ static int command_line_execute(VimState *state, int key)
   if ((s->c == Ctrl_C)
       && s->firstc != '@'
       && !s->break_ctrl_c
-      && !global_busy
-      && !cmd_is_live(ccline.cmdbuff)) {
+      && !global_busy) {
     got_int = false;
   }
 
@@ -1601,13 +1599,17 @@ static int command_line_changed(CommandLineState *s)
              && *p_icm != NUL       // 'inccommand' is set
              && curbuf->b_p_ma      // buffer is modifiable
              && cmdline_star == 0   // not typing a password
-             && cmd_is_live(ccline.cmdbuff)
+             && cmd_can_preview(ccline.cmdbuff)
              && !vpeekc_any()) {
-    s->live = true;
-    // process a "live" command ('inccommand')
-    do_cmdline(ccline.cmdbuff, NULL, NULL, DOCMD_KEEPLINE|DOCMD_LIVE);
-
-    // restore the window "view"
+    // Show 'inccommand' preview. It works like this:
+    //    1. Do the command.
+    //    2. Command implementation detects CMDPREVIEW state, then:
+    //       - Update the screen while the effects are in place.
+    //       - Immediately undo the effects.
+    State |= CMDPREVIEW;
+    do_cmdline(ccline.cmdbuff, NULL, NULL, DOCMD_KEEPLINE|DOCMD_NOWAIT);
+
+    // Restore the window "view".
     curwin->w_cursor   = s->old_cursor;
     curwin->w_curswant = s->old_curswant;
     curwin->w_leftcol  = s->old_leftcol;
@@ -1617,8 +1619,8 @@ static int command_line_changed(CommandLineState *s)
     update_topline();
 
     redrawcmdline();
-  } else if (s->live) {
-    s->live = false;
+  } else if (State & CMDPREVIEW) {
+    State = (State & ~CMDPREVIEW);
     update_screen(SOME_VALID);  // Clear 'inccommand' preview.
   }
 
diff --git a/src/nvim/terminal.c b/src/nvim/terminal.c
index 499716a7a8..bd7b9fc58f 100644
--- a/src/nvim/terminal.c
+++ b/src/nvim/terminal.c
@@ -955,7 +955,6 @@ static void invalidate_terminal(Terminal *term, int start_row, int end_row)
 
 static void refresh_terminal(Terminal *term)
 {
-  // TODO(SplinterOfChaos): Find the condition that makes term->buf invalid.
   buf_T *buf = handle_get_buffer(term->buf_handle);
   bool valid = true;
   if (!buf || !(valid = buf_valid(buf))) {
diff --git a/src/nvim/vim.h b/src/nvim/vim.h
index 6bbd9b58ef..32eba55c18 100644
--- a/src/nvim/vim.h
+++ b/src/nvim/vim.h
@@ -104,6 +104,7 @@ Error: configure did not run properly.Check auto/config.log.
 #define CONFIRM         0x800   /* ":confirm" prompt */
 #define SELECTMODE      0x1000  /* Select mode, only for mappings */
 #define TERM_FOCUS      0x2000  // Terminal focus mode
+#define CMDPREVIEW      0x4000  // Showing 'inccommand' command "live" preview.
 
 // all mode bits used for mapping
 #define MAP_ALL_MODES   (0x3f | SELECTMODE | TERM_FOCUS)