'inccommand': Restore cursor/view if cancelled.

Restore cursor position and window "view", if command is cancelled.
This is how 'incsearch' works.

src/nvim/ex_getln.c

@@ -1599,6 +1599,16 @@ static int command_line_changed(CommandLineState *s)
              && cmd_is_live(ccline.cmdbuff)) {
     // process a "live" command ('inccommand')
     do_cmdline(ccline.cmdbuff, NULL, NULL, DOCMD_KEEPLINE|DOCMD_LIVE);
+
+    // restore the window "view"
+    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;
+    update_topline();
+
     redrawcmdline();
   }
 

test/functional/ui/inccommand_spec.lua

@@ -413,7 +413,7 @@ describe(":substitute, 'inccommand' preserves undo", function()
       insert("X")
       feed("IY<esc>")
       feed(":%s/tw/MO/<esc>")
-      -- using execute("undo") here will result in a "Press ENTER" prompt
+      -- execute("undo") here would cause "Press ENTER".
       feed("u")
       expect(default_text:gsub("Inc", "XInc"))
       feed("u")
@@ -430,6 +430,7 @@ describe(":substitute, 'inccommand' preserves undo", function()
 
       if case == "split" then
         screen:expect([[
+          Inc substitution on |
           ^MOo lines           |
                               |
           {15:~                   }|
@@ -438,7 +439,6 @@ describe(":substitute, 'inccommand' preserves undo", function()
           {15:~                   }|
           {15:~                   }|
           {15:~                   }|
-          {15:~                   }|
           Already...st change |
         ]])
       else
@@ -482,6 +482,7 @@ describe(":substitute, 'inccommand' preserves undo", function()
 
       if case == "split" then
         screen:expect([[
+          Inc substitution on |
           two line^s           |
                               |
           {15:~                   }|
@@ -490,7 +491,6 @@ describe(":substitute, 'inccommand' preserves undo", function()
           {15:~                   }|
           {15:~                   }|
           {15:~                   }|
-          {15:~                   }|
           Already...st change |
         ]])
       else
@@ -522,6 +522,7 @@ describe(":substitute, 'inccommand' preserves undo", function()
 
       if case == "split" then
         screen:expect([[
+          Inc substitution on |
           ^MOo lines           |
                               |
           {15:~                   }|
@@ -530,7 +531,6 @@ describe(":substitute, 'inccommand' preserves undo", function()
           {15:~                   }|
           {15:~                   }|
           {15:~                   }|
-          {15:~                   }|
           Already...st change |
         ]])
       else
@@ -564,6 +564,7 @@ describe(":substitute, 'inccommand' preserves undo", function()
       feed("u")
       if case == "split" then
         screen:expect([[
+          Inc substitution on |
           ^MOo lines           |
                               |
           {15:~                   }|
@@ -572,7 +573,6 @@ describe(":substitute, 'inccommand' preserves undo", function()
           {15:~                   }|
           {15:~                   }|
           {15:~                   }|
-          {15:~                   }|
           Already...st change |
         ]])
       else
@@ -602,7 +602,8 @@ describe(":substitute, 'inccommand' preserves undo", function()
 
       if case == "split" then
         screen:expect([[
-          ^two lines           |
+          ^LInc substitution on|
+          two lines           |
                               |
           {15:~                   }|
           {15:~                   }|
@@ -610,7 +611,6 @@ describe(":substitute, 'inccommand' preserves undo", function()
           {15:~                   }|
           {15:~                   }|
           {15:~                   }|
-          {15:~                   }|
           Already...st change |
         ]])
       elseif case == "" then
@@ -705,7 +705,7 @@ describe(":substitute, inccommand=split", function()
     ]])
   end)
 
-  it('shows split window with empty replacement', function()
+  it('shows preview with empty replacement', function()
     feed(":%s/tw/")
     screen:expect([[
       Inc substitution on           |
@@ -727,11 +727,11 @@ describe(":substitute, inccommand=split", function()
 
     feed("x")
     screen:expect([[
-      xo lines                      |
       Inc substitution on           |
       xo lines                      |
                                     |
       {15:~                             }|
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |2| {12:x}o lines                  |
       |4| {12:x}o lines                  |
@@ -746,11 +746,11 @@ describe(":substitute, inccommand=split", function()
 
     feed("<bs>")
     screen:expect([[
-      o lines                       |
       Inc substitution on           |
       o lines                       |
                                     |
       {15:~                             }|
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |2| o lines                   |
       |4| o lines                   |
@@ -768,11 +768,11 @@ describe(":substitute, inccommand=split", function()
   it('shows split window when typing replacement', function()
     feed(":%s/tw/XX")
     screen:expect([[
-      XXo lines                     |
       Inc substitution on           |
       XXo lines                     |
                                     |
       {15:~                             }|
+      {15:~                             }|
       {11:[No Name] [+]                 }|
       |2| {12:XX}o lines                 |
       |4| {12:XX}o lines                 |
@@ -831,7 +831,7 @@ describe(":substitute, inccommand=split", function()
     ]])
   end)
 
-  it('highlights the replacement text correctly', function()
+  it('highlights the replacement text', function()
     feed('ggO')
     feed('M     M       M<esc>')
     feed(':%s/M/123/g')
@@ -855,9 +855,10 @@ describe(":substitute, inccommand=split", function()
   end)
 
   it('actually replaces text', function()
-    feed(":%s/tw/XX/g<enter>")
+    feed(":%s/tw/XX/g<Enter>")
 
     screen:expect([[
+      Inc substitution on           |
       XXo lines                     |
       Inc substitution on           |
       ^XXo lines                     |
@@ -871,7 +872,6 @@ describe(":substitute, inccommand=split", function()
       {15:~                             }|
       {15:~                             }|
       {15:~                             }|
-      {15:~                             }|
       :%s/tw/XX/g                   |
     ]])
   end)
@@ -884,11 +884,11 @@ describe(":substitute, inccommand=split", function()
 
     feed(":%s/tw/X")
     screen:expect([[
+      Inc substitution on           |
       BBo lines                     |
       Inc substitution on           |
       Xo lines                      |
       Inc substitution on           |
-      Xo lines                      |
       {11:[No Name] [+]                 }|
       |1001| {12:X}o lines               |
       |1003| {12:X}o lines               |
@@ -922,13 +922,13 @@ describe(":substitute, inccommand=split", function()
   end)
 
   it('works with the n flag', function()
-    feed(":%s/tw/Mix/n<enter>")
+    feed(":%s/tw/Mix/n<Enter>")
     screen:expect([[
-      ^two lines                     |
       Inc substitution on           |
       two lines                     |
-                                    |
+      Inc substitution on           |
-      {15:~                             }|
+      two lines                     |
+      ^                              |
       {15:~                             }|
       {15:~                             }|
       {15:~                             }|
@@ -1303,10 +1303,12 @@ describe("'inccommand' split windows", function()
   it('work after more splits', function()
     refresh()
 
+    feed("gg")
     execute("vsplit")
     execute("split")
     feed(":%s/tw")
     screen:expect([[
+      Inc substitution on {10:|}Inc substitution on|
       two lines           {10:|}two lines          |
                           {10:|}                   |
       {15:~                   }{10:|}{15:~                  }|
@@ -1320,13 +1322,12 @@ describe("'inccommand' split windows", function()
       {15:~                   }{10:|}{15:~                  }|
       {15:~                   }{10:|}{15:~                  }|
       {15:~                   }{10:|}{15:~                  }|
-      {15:~                   }{10:|}{15:~                  }|
       {11:[No Name] [+]       }{10:|}{15:~                  }|
+      Inc substitution on {10:|}{15:~                  }|
       two lines           {10:|}{15:~                  }|
                           {10:|}{15:~                  }|
       {15:~                   }{10:|}{15:~                  }|
       {15:~                   }{10:|}{15:~                  }|
-      {15:~                   }{10:|}{15:~                  }|
       {10:[No Name] [+]        [No Name] [+]      }|
       |2| two lines                           |
                                               |