ex_getln: refactor command line mode to use the `state_enter` loop

Split `getcmdline()` into command_line_{enter,check,execute}`

1 files changed, 1135 insertions, 1125 deletions

diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index 38670052bb..19b21875ad 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -160,32 +160,7 @@ static int hislen = 0;                  /* actual length of history tables */
 static int cmd_hkmap = 0;       /* Hebrew mapping during command line */
 
 static int cmd_fkmap = 0;       /* Farsi mapping during command line */
-
-/*
- * getcmdline() - accept a command line starting with firstc.
- *
- * firstc == ':'	    get ":" command line.
- * firstc == '/' or '?'	    get search pattern
- * firstc == '='	    get expression
- * firstc == '@'	    get text for input() function
- * firstc == '>'	    get text for debug mode
- * firstc == NUL	    get text for :insert command
- * firstc == -1		    like NUL, and break on CTRL-C
- *
- * The line is collected in ccline.cmdbuff, which is reallocated to fit the
- * command line.
- *
- * Careful: getcmdline() can be called recursively!
- *
- * Return pointer to allocated string if there is a commandline, NULL
- * otherwise.
- */
-char_u *
-getcmdline (
-    int firstc,
-    long count,              // only used for incremental search
-    int indent               // indent for inside conditionals
-)
+static uint8_t *command_line_enter(int firstc, long count, int indent)
 {
   CommandLineState state, *s = &state;
   memset(s, 0, sizeof(CommandLineState));
@@ -298,650 +273,650 @@ getcmdline (
 
   did_emsg = false;
   got_int = false;
+  s->state.check = command_line_check;
+  s->state.execute = command_line_execute;
+  state_enter(&s->state);
 
-  // Collect the command string, handling editing keys.
-  for (;;) {
-    redir_off = true;           // Don't redirect the typed command.
-                                // Repeated, because a ":redir" inside
-                                // completion may switch it on.
-    quit_more = false;          // reset after CTRL-D which had a more-prompt
+  cmdmsg_rl = false;
 
-    cursorcmd();                // set the cursor on the right spot
+  cmd_fkmap = 0;
 
-    // Get a character.  Ignore K_IGNORE, it should not do anything, such
-    // as stop completion.
-    input_enable_events();
-    do {
-      s->c = safe_vgetc();
-    } while (s->c == K_IGNORE || s->c == K_PASTE);
-    input_disable_events();
+  ExpandCleanup(&s->xpc);
+  ccline.xpc = NULL;
 
-    if (s->c == K_EVENT) {
-      queue_process_events(loop.events);
-      continue;
-    }
+  if (s->did_incsearch) {
+    curwin->w_cursor = s->old_cursor;
+    curwin->w_curswant = s->old_curswant;
+    curwin->w_leftcol = s->old_leftcol;
+    curwin->w_topline = s->old_topline;
+    curwin->w_topfill = s->old_topfill;
+    curwin->w_botline = s->old_botline;
+    highlight_match = false;
+    validate_cursor();          // needed for TAB
+    redraw_later(SOME_VALID);
+  }
 
-    if (KeyTyped) {
-      s->some_key_typed = true;
-      if (cmd_hkmap) {
-        s->c = hkmap(s->c);
+  if (ccline.cmdbuff != NULL) {
+    // Put line in history buffer (":" and "=" only when it was typed).
+    if (ccline.cmdlen && s->firstc != NUL
+        && (s->some_key_typed || s->histype == HIST_SEARCH)) {
+      add_to_history(s->histype, ccline.cmdbuff, true,
+          s->histype == HIST_SEARCH ? s->firstc : NUL);
+      if (s->firstc == ':') {
+        xfree(new_last_cmdline);
+        new_last_cmdline = vim_strsave(ccline.cmdbuff);
       }
+    }
 
-      if (cmd_fkmap) {
-        s->c = cmdl_fkmap(s->c);
+    if (s->gotesc) {           // abandon command line
+      xfree(ccline.cmdbuff);
+      ccline.cmdbuff = NULL;
+      if (msg_scrolled == 0) {
+        compute_cmdrow();
       }
+      MSG("");
+      redraw_cmdline = true;
+    }
+  }
 
-      if (cmdmsg_rl && !KeyStuffed) {
-        // Invert horizontal movements and operations.  Only when
-        // typed by the user directly, not when the result of a
-        // mapping.
-        switch (s->c) {
-        case K_RIGHT:   s->c = K_LEFT; break;
-        case K_S_RIGHT: s->c = K_S_LEFT; break;
-        case K_C_RIGHT: s->c = K_C_LEFT; break;
-        case K_LEFT:    s->c = K_RIGHT; break;
-        case K_S_LEFT:  s->c = K_S_RIGHT; break;
-        case K_C_LEFT:  s->c = K_C_RIGHT; break;
-        }
-      }
+  // If the screen was shifted up, redraw the whole screen (later).
+  // If the line is too long, clear it, so ruler and shown command do
+  // not get printed in the middle of it.
+  msg_check();
+  msg_scroll = s->save_msg_scroll;
+  redir_off = false;
+
+  // When the command line was typed, no need for a wait-return prompt.
+  if (s->some_key_typed) {
+    need_wait_return = false;
+  }
+
+  State = s->save_State;
+  setmouse();
+  ui_cursor_shape();            // may show different cursor shape
+
+  {
+    char_u *p = ccline.cmdbuff;
+
+    // Make ccline empty, getcmdline() may try to use it.
+    ccline.cmdbuff = NULL;
+    return p;
+  }
+}
+
+static int command_line_check(VimState *state)
+{
+  redir_off = true;        // Don't redirect the typed command.
+  // Repeated, because a ":redir" inside
+  // completion may switch it on.
+  quit_more = false;       // reset after CTRL-D which had a more-prompt
+
+  cursorcmd();             // set the cursor on the right spot
+  return 1;
+}
+
+static int command_line_execute(VimState *state, int key)
+{
+  if (key == K_IGNORE || key == K_PASTE) {
+    return -1;  // get another key
+  }
+
+  CommandLineState *s = (CommandLineState *)state;
+  s->c = key;
+
+  if (s->c == K_EVENT) {
+    queue_process_events(loop.events);
+    return 1;
+  }
+
+  if (KeyTyped) {
+    s->some_key_typed = true;
+    if (cmd_hkmap) {
+      s->c = hkmap(s->c);
     }
 
-    // Ignore got_int when CTRL-C was typed here.
-    // Don't ignore it in :global, we really need to break then, e.g., for
-    // ":g/pat/normal /pat" (without the <CR>).
-    // Don't ignore it for the input() function.
-    if ((s->c == Ctrl_C)
-        && s->firstc != '@'
-        && !s->break_ctrl_c
-        && !global_busy) {
-      got_int = false;
+    if (cmd_fkmap) {
+      s->c = cmdl_fkmap(s->c);
     }
 
-    // free old command line when finished moving around in the history
-    // list
-    if (s->lookfor != NULL
-        && s->c != K_S_DOWN && s->c != K_S_UP
-        && s->c != K_DOWN && s->c != K_UP
-        && s->c != K_PAGEDOWN && s->c != K_PAGEUP
-        && s->c != K_KPAGEDOWN && s->c != K_KPAGEUP
-        && s->c != K_LEFT && s->c != K_RIGHT
-        && (s->xpc.xp_numfiles > 0 || (s->c != Ctrl_P && s->c != Ctrl_N))) {
-      xfree(s->lookfor);
-      s->lookfor = NULL;
+    if (cmdmsg_rl && !KeyStuffed) {
+      // Invert horizontal movements and operations.  Only when
+      // typed by the user directly, not when the result of a
+      // mapping.
+      switch (s->c) {
+      case K_RIGHT:   s->c = K_LEFT; break;
+      case K_S_RIGHT: s->c = K_S_LEFT; break;
+      case K_C_RIGHT: s->c = K_C_LEFT; break;
+      case K_LEFT:    s->c = K_RIGHT; break;
+      case K_S_LEFT:  s->c = K_S_RIGHT; break;
+      case K_C_LEFT:  s->c = K_C_RIGHT; break;
+      }
     }
+  }
 
-    // When there are matching completions to select <S-Tab> works like
-    // CTRL-P (unless 'wc' is <S-Tab>).
-    if (s->c != p_wc && s->c == K_S_TAB && s->xpc.xp_numfiles > 0) {
+  // Ignore got_int when CTRL-C was typed here.
+  // Don't ignore it in :global, we really need to break then, e.g., for
+  // ":g/pat/normal /pat" (without the <CR>).
+  // Don't ignore it for the input() function.
+  if ((s->c == Ctrl_C)
+      && s->firstc != '@'
+      && !s->break_ctrl_c
+      && !global_busy) {
+    got_int = false;
+  }
+
+  // free old command line when finished moving around in the history
+  // list
+  if (s->lookfor != NULL
+      && s->c != K_S_DOWN && s->c != K_S_UP
+      && s->c != K_DOWN && s->c != K_UP
+      && s->c != K_PAGEDOWN && s->c != K_PAGEUP
+      && s->c != K_KPAGEDOWN && s->c != K_KPAGEUP
+      && s->c != K_LEFT && s->c != K_RIGHT
+      && (s->xpc.xp_numfiles > 0 || (s->c != Ctrl_P && s->c != Ctrl_N))) {
+    xfree(s->lookfor);
+    s->lookfor = NULL;
+  }
+
+  // When there are matching completions to select <S-Tab> works like
+  // CTRL-P (unless 'wc' is <S-Tab>).
+  if (s->c != p_wc && s->c == K_S_TAB && s->xpc.xp_numfiles > 0) {
+    s->c = Ctrl_P;
+  }
+
+  // Special translations for 'wildmenu'
+  if (s->did_wild_list && p_wmnu) {
+    if (s->c == K_LEFT) {
       s->c = Ctrl_P;
+    } else if (s->c == K_RIGHT) {
+      s->c = Ctrl_N;
     }
+  }
 
-    // Special translations for 'wildmenu'
-    if (s->did_wild_list && p_wmnu) {
-      if (s->c == K_LEFT) {
-        s->c = Ctrl_P;
-      } else if (s->c == K_RIGHT) {
-        s->c = Ctrl_N;
-      }
-    }
+  // Hitting CR after "emenu Name.": complete submenu
+  if (s->xpc.xp_context == EXPAND_MENUNAMES && p_wmnu
+      && ccline.cmdpos > 1
+      && ccline.cmdbuff[ccline.cmdpos - 1] == '.'
+      && ccline.cmdbuff[ccline.cmdpos - 2] != '\\'
+      && (s->c == '\n' || s->c == '\r' || s->c == K_KENTER)) {
+    s->c = K_DOWN;
+  }
 
-    // Hitting CR after "emenu Name.": complete submenu
-    if (s->xpc.xp_context == EXPAND_MENUNAMES && p_wmnu
-        && ccline.cmdpos > 1
-        && ccline.cmdbuff[ccline.cmdpos - 1] == '.'
-        && ccline.cmdbuff[ccline.cmdpos - 2] != '\\'
-        && (s->c == '\n' || s->c == '\r' || s->c == K_KENTER)) {
-      s->c = K_DOWN;
+  // free expanded names when finished walking through matches
+  if (s->xpc.xp_numfiles != -1
+      && !(s->c == p_wc && KeyTyped) && s->c != p_wcm
+      && s->c != Ctrl_N && s->c != Ctrl_P && s->c != Ctrl_A
+      && s->c != Ctrl_L) {
+    (void)ExpandOne(&s->xpc, NULL, NULL, 0, WILD_FREE);
+    s->did_wild_list = false;
+    if (!p_wmnu || (s->c != K_UP && s->c != K_DOWN)) {
+      s->xpc.xp_context = EXPAND_NOTHING;
     }
+    s->wim_index = 0;
+    if (p_wmnu && wild_menu_showing != 0) {
+      int skt = KeyTyped;
+      int old_RedrawingDisabled = RedrawingDisabled;
 
-    // free expanded names when finished walking through matches
-    if (s->xpc.xp_numfiles != -1
-        && !(s->c == p_wc && KeyTyped) && s->c != p_wcm
-        && s->c != Ctrl_N && s->c != Ctrl_P && s->c != Ctrl_A
-        && s->c != Ctrl_L) {
-      (void)ExpandOne(&s->xpc, NULL, NULL, 0, WILD_FREE);
-      s->did_wild_list = false;
-      if (!p_wmnu || (s->c != K_UP && s->c != K_DOWN)) {
-        s->xpc.xp_context = EXPAND_NOTHING;
+      if (ccline.input_fn) {
+        RedrawingDisabled = 0;
       }
-      s->wim_index = 0;
-      if (p_wmnu && wild_menu_showing != 0) {
-        int skt = KeyTyped;
-        int old_RedrawingDisabled = RedrawingDisabled;
 
-        if (ccline.input_fn) {
-          RedrawingDisabled = 0;
-        }
-
-        if (wild_menu_showing == WM_SCROLLED) {
-          // Entered command line, move it up
-          cmdline_row--;
-          redrawcmd();
-        } else if (save_p_ls != -1) {
-          // restore 'laststatus' and 'winminheight'
-          p_ls = save_p_ls;
-          p_wmh = save_p_wmh;
-          last_status(false);
-          save_cmdline(&s->save_ccline);
-          update_screen(VALID);                 // redraw the screen NOW
-          restore_cmdline(&s->save_ccline);
-          redrawcmd();
-          save_p_ls = -1;
-        } else {
-          win_redraw_last_status(topframe);
-          redraw_statuslines();
-        }
-        KeyTyped = skt;
-        wild_menu_showing = 0;
-        if (ccline.input_fn) {
-          RedrawingDisabled = old_RedrawingDisabled;
-        }
+      if (wild_menu_showing == WM_SCROLLED) {
+        // Entered command line, move it up
+        cmdline_row--;
+        redrawcmd();
+      } else if (save_p_ls != -1) {
+        // restore 'laststatus' and 'winminheight'
+        p_ls = save_p_ls;
+        p_wmh = save_p_wmh;
+        last_status(false);
+        save_cmdline(&s->save_ccline);
+        update_screen(VALID);                 // redraw the screen NOW
+        restore_cmdline(&s->save_ccline);
+        redrawcmd();
+        save_p_ls = -1;
+      } else {
+        win_redraw_last_status(topframe);
+        redraw_statuslines();
+      }
+      KeyTyped = skt;
+      wild_menu_showing = 0;
+      if (ccline.input_fn) {
+        RedrawingDisabled = old_RedrawingDisabled;
       }
     }
+  }
 
-    // Special translations for 'wildmenu'
-    if (s->xpc.xp_context == EXPAND_MENUNAMES && p_wmnu) {
-      // Hitting <Down> after "emenu Name.": complete submenu
-      if (s->c == K_DOWN && ccline.cmdpos > 0
-          && ccline.cmdbuff[ccline.cmdpos - 1] == '.') {
-        s->c = p_wc;
-      } else if (s->c == K_UP) {
-        // Hitting <Up>: Remove one submenu name in front of the
-        // cursor
-        int found = false;
+  // Special translations for 'wildmenu'
+  if (s->xpc.xp_context == EXPAND_MENUNAMES && p_wmnu) {
+    // Hitting <Down> after "emenu Name.": complete submenu
+    if (s->c == K_DOWN && ccline.cmdpos > 0
+        && ccline.cmdbuff[ccline.cmdpos - 1] == '.') {
+      s->c = p_wc;
+    } else if (s->c == K_UP) {
+      // Hitting <Up>: Remove one submenu name in front of the
+      // cursor
+      int found = false;
+
+      s->j = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
+      s->i = 0;
+      while (--s->j > 0) {
+        // check for start of menu name
+        if (ccline.cmdbuff[s->j] == ' '
+            && ccline.cmdbuff[s->j - 1] != '\\') {
+          s->i = s->j + 1;
+          break;
+        }
 
-        s->j = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
-        s->i = 0;
-        while (--s->j > 0) {
-          // check for start of menu name
-          if (ccline.cmdbuff[s->j] == ' '
-              && ccline.cmdbuff[s->j - 1] != '\\') {
+        // check for start of submenu name
+        if (ccline.cmdbuff[s->j] == '.'
+            && ccline.cmdbuff[s->j - 1] != '\\') {
+          if (found) {
             s->i = s->j + 1;
             break;
-          }
-
-          // check for start of submenu name
-          if (ccline.cmdbuff[s->j] == '.'
-              && ccline.cmdbuff[s->j - 1] != '\\') {
-            if (found) {
-              s->i = s->j + 1;
-              break;
-            } else {
-              found = true;
-            }
+          } else {
+            found = true;
           }
         }
-        if (s->i > 0) {
-          cmdline_del(s->i);
-        }
-        s->c = p_wc;
-        s->xpc.xp_context = EXPAND_NOTHING;
       }
+      if (s->i > 0) {
+        cmdline_del(s->i);
+      }
+      s->c = p_wc;
+      s->xpc.xp_context = EXPAND_NOTHING;
     }
-    if ((s->xpc.xp_context == EXPAND_FILES
-         || s->xpc.xp_context == EXPAND_DIRECTORIES
-         || s->xpc.xp_context == EXPAND_SHELLCMD) && p_wmnu) {
-      char_u upseg[5];
-
-      upseg[0] = PATHSEP;
-      upseg[1] = '.';
-      upseg[2] = '.';
-      upseg[3] = PATHSEP;
-      upseg[4] = NUL;
-
-      if (s->c == K_DOWN
-          && ccline.cmdpos > 0
-          && ccline.cmdbuff[ccline.cmdpos - 1] == PATHSEP
-          && (ccline.cmdpos < 3
-              || ccline.cmdbuff[ccline.cmdpos - 2] != '.'
-              || ccline.cmdbuff[ccline.cmdpos - 3] != '.')) {
-        // go down a directory
-        s->c = p_wc;
-      } else if (STRNCMP(s->xpc.xp_pattern, upseg + 1, 3) == 0
-          && s->c == K_DOWN) {
-        // If in a direct ancestor, strip off one ../ to go down
-        int found = false;
-
-        s->j = ccline.cmdpos;
-        s->i = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
-        while (--s->j > s->i) {
-          if (has_mbyte) {
-            s->j -= (*mb_head_off)(ccline.cmdbuff, ccline.cmdbuff + s->j);
-          }
-          if (vim_ispathsep(ccline.cmdbuff[s->j])) {
-            found = true;
-            break;
-          }
+  }
+  if ((s->xpc.xp_context == EXPAND_FILES
+       || s->xpc.xp_context == EXPAND_DIRECTORIES
+       || s->xpc.xp_context == EXPAND_SHELLCMD) && p_wmnu) {
+    char_u upseg[5];
+
+    upseg[0] = PATHSEP;
+    upseg[1] = '.';
+    upseg[2] = '.';
+    upseg[3] = PATHSEP;
+    upseg[4] = NUL;
+
+    if (s->c == K_DOWN
+        && ccline.cmdpos > 0
+        && ccline.cmdbuff[ccline.cmdpos - 1] == PATHSEP
+        && (ccline.cmdpos < 3
+            || ccline.cmdbuff[ccline.cmdpos - 2] != '.'
+            || ccline.cmdbuff[ccline.cmdpos - 3] != '.')) {
+      // go down a directory
+      s->c = p_wc;
+    } else if (STRNCMP(s->xpc.xp_pattern, upseg + 1, 3) == 0
+        && s->c == K_DOWN) {
+      // If in a direct ancestor, strip off one ../ to go down
+      int found = false;
+
+      s->j = ccline.cmdpos;
+      s->i = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
+      while (--s->j > s->i) {
+        if (has_mbyte) {
+          s->j -= (*mb_head_off)(ccline.cmdbuff, ccline.cmdbuff + s->j);
         }
-        if (found
-            && ccline.cmdbuff[s->j - 1] == '.'
-            && ccline.cmdbuff[s->j - 2] == '.'
-            && (vim_ispathsep(ccline.cmdbuff[s->j - 3]) || s->j == s->i + 2)) {
-          cmdline_del(s->j - 2);
-          s->c = p_wc;
+        if (vim_ispathsep(ccline.cmdbuff[s->j])) {
+          found = true;
+          break;
         }
-      } else if (s->c == K_UP) {
-        // go up a directory
-        int found = false;
+      }
+      if (found
+          && ccline.cmdbuff[s->j - 1] == '.'
+          && ccline.cmdbuff[s->j - 2] == '.'
+          && (vim_ispathsep(ccline.cmdbuff[s->j - 3]) || s->j == s->i + 2)) {
+        cmdline_del(s->j - 2);
+        s->c = p_wc;
+      }
+    } else if (s->c == K_UP) {
+      // go up a directory
+      int found = false;
 
-        s->j = ccline.cmdpos - 1;
-        s->i = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
-        while (--s->j > s->i) {
-          if (has_mbyte) {
-            s->j -= (*mb_head_off)(ccline.cmdbuff, ccline.cmdbuff + s->j);
-          }
-          if (vim_ispathsep(ccline.cmdbuff[s->j])
+      s->j = ccline.cmdpos - 1;
+      s->i = (int)(s->xpc.xp_pattern - ccline.cmdbuff);
+      while (--s->j > s->i) {
+        if (has_mbyte) {
+          s->j -= (*mb_head_off)(ccline.cmdbuff, ccline.cmdbuff + s->j);
+        }
+        if (vim_ispathsep(ccline.cmdbuff[s->j])
 #ifdef BACKSLASH_IN_FILENAME
-              && vim_strchr(" *?[{`$%#", ccline.cmdbuff[j + 1])
-              == NULL
+            && vim_strchr(" *?[{`$%#", ccline.cmdbuff[j + 1])
+            == NULL
 #endif
-              ) {
-            if (found) {
-              s->i = s->j + 1;
-              break;
-            } else {
-              found = true;
-            }
+            ) {
+          if (found) {
+            s->i = s->j + 1;
+            break;
+          } else {
+            found = true;
           }
         }
+      }
 
-        if (!found) {
-          s->j = s->i;
-        } else if (STRNCMP(ccline.cmdbuff + s->j, upseg, 4) == 0) {
-          s->j += 4;
-        } else if (STRNCMP(ccline.cmdbuff + s->j, upseg + 1, 3) == 0
-                 && s->j == s->i) {
-          s->j += 3;
-        } else {
-          s->j = 0;
-        }
-
-        if (s->j > 0) {
-          // TODO(tarruda): this is only for DOS/UNIX systems - need to put in
-          // machine-specific stuff here and in upseg init
-          cmdline_del(s->j);
-          put_on_cmdline(upseg + 1, 3, false);
-        } else if (ccline.cmdpos > s->i) {
-          cmdline_del(s->i);
-        }
+      if (!found) {
+        s->j = s->i;
+      } else if (STRNCMP(ccline.cmdbuff + s->j, upseg, 4) == 0) {
+        s->j += 4;
+      } else if (STRNCMP(ccline.cmdbuff + s->j, upseg + 1, 3) == 0
+               && s->j == s->i) {
+        s->j += 3;
+      } else {
+        s->j = 0;
+      }
 
-        // Now complete in the new directory. Set KeyTyped in case the
-        // Up key came from a mapping.
-        s->c = p_wc;
-        KeyTyped = true;
+      if (s->j > 0) {
+        // TODO(tarruda): this is only for DOS/UNIX systems - need to put in
+        // machine-specific stuff here and in upseg init
+        cmdline_del(s->j);
+        put_on_cmdline(upseg + 1, 3, false);
+      } else if (ccline.cmdpos > s->i) {
+        cmdline_del(s->i);
       }
+
+      // Now complete in the new directory. Set KeyTyped in case the
+      // Up key came from a mapping.
+      s->c = p_wc;
+      KeyTyped = true;
     }
+  }
 
-    // CTRL-\ CTRL-N goes to Normal mode, CTRL-\ CTRL-G goes to Insert
-    // mode when 'insertmode' is set, CTRL-\ e prompts for an expression.
-    if (s->c == Ctrl_BSL) {
-      ++no_mapping;
-      ++allow_keys;
-      s->c = plain_vgetc();
-      --no_mapping;
-      --allow_keys;
-      // CTRL-\ e doesn't work when obtaining an expression, unless it
-      // is in a mapping.
-      if (s->c != Ctrl_N && s->c != Ctrl_G && (s->c != 'e'
-                                         || (ccline.cmdfirstc == '=' &&
-                                             KeyTyped))) {
-        vungetc(s->c);
-        s->c = Ctrl_BSL;
-      } else if (s->c == 'e') {
-        char_u  *p = NULL;
-        int len;
-
-        // Replace the command line with the result of an expression.
-        // Need to save and restore the current command line, to be
-        // able to enter a new one...
-        if (ccline.cmdpos == ccline.cmdlen) {
-          new_cmdpos = 99999;           // keep it at the end
-        } else {
-          new_cmdpos = ccline.cmdpos;
-        }
+  // CTRL-\ CTRL-N goes to Normal mode, CTRL-\ CTRL-G goes to Insert
+  // mode when 'insertmode' is set, CTRL-\ e prompts for an expression.
+  if (s->c == Ctrl_BSL) {
+    ++no_mapping;
+    ++allow_keys;
+    s->c = plain_vgetc();
+    --no_mapping;
+    --allow_keys;
+    // CTRL-\ e doesn't work when obtaining an expression, unless it
+    // is in a mapping.
+    if (s->c != Ctrl_N && s->c != Ctrl_G && (s->c != 'e'
+                                       || (ccline.cmdfirstc == '=' &&
+                                           KeyTyped))) {
+      vungetc(s->c);
+      s->c = Ctrl_BSL;
+    } else if (s->c == 'e') {
+      char_u  *p = NULL;
+      int len;
+
+      // Replace the command line with the result of an expression.
+      // Need to save and restore the current command line, to be
+      // able to enter a new one...
+      if (ccline.cmdpos == ccline.cmdlen) {
+        new_cmdpos = 99999;           // keep it at the end
+      } else {
+        new_cmdpos = ccline.cmdpos;
+      }
 
+      save_cmdline(&s->save_ccline);
+      s->c = get_expr_register();
+      restore_cmdline(&s->save_ccline);
+      if (s->c == '=') {
+        // Need to save and restore ccline.  And set "textlock"
+        // to avoid nasty things like going to another buffer when
+        // evaluating an expression.
         save_cmdline(&s->save_ccline);
-        s->c = get_expr_register();
+        ++textlock;
+        p = get_expr_line();
+        --textlock;
         restore_cmdline(&s->save_ccline);
-        if (s->c == '=') {
-          // Need to save and restore ccline.  And set "textlock"
-          // to avoid nasty things like going to another buffer when
-          // evaluating an expression.
-          save_cmdline(&s->save_ccline);
-          ++textlock;
-          p = get_expr_line();
-          --textlock;
-          restore_cmdline(&s->save_ccline);
-
-          if (p != NULL) {
-            len = (int)STRLEN(p);
-            realloc_cmdbuff(len + 1);
-            ccline.cmdlen = len;
-            STRCPY(ccline.cmdbuff, p);
-            xfree(p);
-
-            // Restore the cursor or use the position set with
-            // set_cmdline_pos().
-            if (new_cmdpos > ccline.cmdlen) {
-              ccline.cmdpos = ccline.cmdlen;
-            } else {
-              ccline.cmdpos = new_cmdpos;
-            }
 
-            KeyTyped = false;                 // Don't do p_wc completion.
-            redrawcmd();
-            goto cmdline_changed;
+        if (p != NULL) {
+          len = (int)STRLEN(p);
+          realloc_cmdbuff(len + 1);
+          ccline.cmdlen = len;
+          STRCPY(ccline.cmdbuff, p);
+          xfree(p);
+
+          // Restore the cursor or use the position set with
+          // set_cmdline_pos().
+          if (new_cmdpos > ccline.cmdlen) {
+            ccline.cmdpos = ccline.cmdlen;
+          } else {
+            ccline.cmdpos = new_cmdpos;
           }
+
+          KeyTyped = false;                 // Don't do p_wc completion.
+          redrawcmd();
+          goto cmdline_changed;
         }
-        beep_flush();
-        got_int = false;                // don't abandon the command line
-        did_emsg = false;
-        emsg_on_display = false;
-        redrawcmd();
-        goto cmdline_not_changed;
-      } else {
-        if (s->c == Ctrl_G && p_im && restart_edit == 0) {
-          restart_edit = 'a';
-        }
-        s->gotesc = true;        // will free ccline.cmdbuff after putting it
-                                 // in history
-        goto returncmd;          // back to Normal mode
       }
+      beep_flush();
+      got_int = false;                // don't abandon the command line
+      did_emsg = false;
+      emsg_on_display = false;
+      redrawcmd();
+      goto cmdline_not_changed;
+    } else {
+      if (s->c == Ctrl_G && p_im && restart_edit == 0) {
+        restart_edit = 'a';
+      }
+      s->gotesc = true;        // will free ccline.cmdbuff after putting it
+                               // in history
+      return 0;                // back to Normal mode
     }
+  }
 
-    if (s->c == cedit_key || s->c == K_CMDWIN) {
-      if (ex_normal_busy == 0 && got_int == false) {
-        // Open a window to edit the command line (and history).
-        s->c = ex_window();
-        s->some_key_typed = true;
-      }
-    } else {
-      s->c = do_digraph(s->c);
+  if (s->c == cedit_key || s->c == K_CMDWIN) {
+    if (ex_normal_busy == 0 && got_int == false) {
+      // Open a window to edit the command line (and history).
+      s->c = ex_window();
+      s->some_key_typed = true;
     }
+  } else {
+    s->c = do_digraph(s->c);
+  }
 
-    if (s->c == '\n'
-        || s->c == '\r'
-        || s->c == K_KENTER
-        || (s->c == ESC
-          && (!KeyTyped || vim_strchr(p_cpo, CPO_ESC) != NULL))) {
-      // In Ex mode a backslash escapes a newline.
-      if (exmode_active
-          && s->c != ESC
-          && ccline.cmdpos == ccline.cmdlen
-          && ccline.cmdpos > 0
-          && ccline.cmdbuff[ccline.cmdpos - 1] == '\\') {
-        if (s->c == K_KENTER) {
-          s->c = '\n';
-        }
-      } else {
-        s->gotesc = false;         // Might have typed ESC previously, don't
-                                   // truncate the cmdline now.
-        if (ccheck_abbr(s->c + ABBR_OFF)) {
-          goto cmdline_changed;
-        }
+  if (s->c == '\n'
+      || s->c == '\r'
+      || s->c == K_KENTER
+      || (s->c == ESC
+        && (!KeyTyped || vim_strchr(p_cpo, CPO_ESC) != NULL))) {
+    // In Ex mode a backslash escapes a newline.
+    if (exmode_active
+        && s->c != ESC
+        && ccline.cmdpos == ccline.cmdlen
+        && ccline.cmdpos > 0
+        && ccline.cmdbuff[ccline.cmdpos - 1] == '\\') {
+      if (s->c == K_KENTER) {
+        s->c = '\n';
+      }
+    } else {
+      s->gotesc = false;         // Might have typed ESC previously, don't
+                                 // truncate the cmdline now.
+      if (ccheck_abbr(s->c + ABBR_OFF)) {
+        goto cmdline_changed;
+      }
 
-        if (!cmd_silent) {
-          ui_cursor_goto(msg_row, 0);
-          ui_flush();
-        }
-        break;
+      if (!cmd_silent) {
+        ui_cursor_goto(msg_row, 0);
+        ui_flush();
       }
+      return 0;
     }
+  }
 
-    // Completion for 'wildchar' or 'wildcharm' key.
-    // - hitting <ESC> twice means: abandon command line.
-    // - wildcard expansion is only done when the 'wildchar' key is really
-    //   typed, not when it comes from a macro
-    if ((s->c == p_wc && !s->gotesc && KeyTyped) || s->c == p_wcm) {
-      if (s->xpc.xp_numfiles > 0) {       // typed p_wc at least twice
-        // if 'wildmode' contains "list" may still need to list
-        if (s->xpc.xp_numfiles > 1
-            && !s->did_wild_list
-            && (wim_flags[s->wim_index] & WIM_LIST)) {
-          (void)showmatches(&s->xpc, false);
-          redrawcmd();
-          s->did_wild_list = true;
-        }
-
-        if (wim_flags[s->wim_index] & WIM_LONGEST) {
-          s->res = nextwild(&s->xpc, WILD_LONGEST, WILD_NO_BEEP,
-              s->firstc != '@');
-        } else if (wim_flags[s->wim_index] & WIM_FULL) {
-          s->res = nextwild(&s->xpc, WILD_NEXT, WILD_NO_BEEP,
-              s->firstc != '@');
-        } else {
-          s->res = OK;                 // don't insert 'wildchar' now
-        }
-      } else {                    // typed p_wc first time
-        s->wim_index = 0;
-        s->j = ccline.cmdpos;
-
-        // if 'wildmode' first contains "longest", get longest
-        // common part
-        if (wim_flags[0] & WIM_LONGEST) {
-          s->res = nextwild(&s->xpc, WILD_LONGEST, WILD_NO_BEEP,
-              s->firstc != '@');
-        } else {
-          s->res = nextwild(&s->xpc, WILD_EXPAND_KEEP, WILD_NO_BEEP,
-              s->firstc != '@');
-        }
-
-        // if interrupted while completing, behave like it failed
-        if (got_int) {
-          (void)vpeekc();               // remove <C-C> from input stream
-          got_int = false;              // don't abandon the command line
-          (void)ExpandOne(&s->xpc, NULL, NULL, 0, WILD_FREE);
-          s->xpc.xp_context = EXPAND_NOTHING;
-          goto cmdline_changed;
-        }
-
-        // when more than one match, and 'wildmode' first contains
-        // "list", or no change and 'wildmode' contains "longest,list",
-        // list all matches
-        if (s->res == OK && s->xpc.xp_numfiles > 1) {
-          // a "longest" that didn't do anything is skipped (but not
-          // "list:longest")
-          if (wim_flags[0] == WIM_LONGEST && ccline.cmdpos == s->j) {
-            s->wim_index = 1;
-          }
-          if ((wim_flags[s->wim_index] & WIM_LIST)
-              || (p_wmnu && (wim_flags[s->wim_index] & WIM_FULL) != 0)) {
-            if (!(wim_flags[0] & WIM_LONGEST)) {
-              int p_wmnu_save = p_wmnu;
-              p_wmnu = 0;
-              // remove match
-              nextwild(&s->xpc, WILD_PREV, 0, s->firstc != '@');
-              p_wmnu = p_wmnu_save;
-            }
-
-            (void)showmatches(&s->xpc, p_wmnu
-                && ((wim_flags[s->wim_index] & WIM_LIST) == 0));
-            redrawcmd();
-            s->did_wild_list = true;
-
-            if (wim_flags[s->wim_index] & WIM_LONGEST) {
-              nextwild(&s->xpc, WILD_LONGEST, WILD_NO_BEEP,
-                  s->firstc != '@');
-            } else if (wim_flags[s->wim_index] & WIM_FULL) {
-              nextwild(&s->xpc, WILD_NEXT, WILD_NO_BEEP,
-                  s->firstc != '@');
-            }
-          } else {
-            vim_beep(BO_WILD);
-          }
-        } else if (s->xpc.xp_numfiles == -1) {
-          s->xpc.xp_context = EXPAND_NOTHING;
-        }
+  // Completion for 'wildchar' or 'wildcharm' key.
+  // - hitting <ESC> twice means: abandon command line.
+  // - wildcard expansion is only done when the 'wildchar' key is really
+  //   typed, not when it comes from a macro
+  if ((s->c == p_wc && !s->gotesc && KeyTyped) || s->c == p_wcm) {
+    if (s->xpc.xp_numfiles > 0) {       // typed p_wc at least twice
+      // if 'wildmode' contains "list" may still need to list
+      if (s->xpc.xp_numfiles > 1
+          && !s->did_wild_list
+          && (wim_flags[s->wim_index] & WIM_LIST)) {
+        (void)showmatches(&s->xpc, false);
+        redrawcmd();
+        s->did_wild_list = true;
       }
 
-      if (s->wim_index < 3) {
-        ++s->wim_index;
+      if (wim_flags[s->wim_index] & WIM_LONGEST) {
+        s->res = nextwild(&s->xpc, WILD_LONGEST, WILD_NO_BEEP,
+            s->firstc != '@');
+      } else if (wim_flags[s->wim_index] & WIM_FULL) {
+        s->res = nextwild(&s->xpc, WILD_NEXT, WILD_NO_BEEP,
+            s->firstc != '@');
+      } else {
+        s->res = OK;                 // don't insert 'wildchar' now
       }
+    } else {                    // typed p_wc first time
+      s->wim_index = 0;
+      s->j = ccline.cmdpos;
 
-      if (s->c == ESC) {
-        s->gotesc = true;
+      // if 'wildmode' first contains "longest", get longest
+      // common part
+      if (wim_flags[0] & WIM_LONGEST) {
+        s->res = nextwild(&s->xpc, WILD_LONGEST, WILD_NO_BEEP,
+            s->firstc != '@');
+      } else {
+        s->res = nextwild(&s->xpc, WILD_EXPAND_KEEP, WILD_NO_BEEP,
+            s->firstc != '@');
       }
 
-      if (s->res == OK) {
+      // if interrupted while completing, behave like it failed
+      if (got_int) {
+        (void)vpeekc();               // remove <C-C> from input stream
+        got_int = false;              // don't abandon the command line
+        (void)ExpandOne(&s->xpc, NULL, NULL, 0, WILD_FREE);
+        s->xpc.xp_context = EXPAND_NOTHING;
         goto cmdline_changed;
       }
-    }
 
-    s->gotesc = false;
+      // when more than one match, and 'wildmode' first contains
+      // "list", or no change and 'wildmode' contains "longest,list",
+      // list all matches
+      if (s->res == OK && s->xpc.xp_numfiles > 1) {
+        // a "longest" that didn't do anything is skipped (but not
+        // "list:longest")
+        if