Add noinsert and noselect features in completeopt #2564

Backported from vim_dev:
https://groups.google.com/forum/#!searchin/vim_dev/completeopt/vim_dev/tVsk0pdOGvs/fCzBbPkA4w0J

Use case:
https://github.com/Shougo/neocomplcache.vim/issues/426

Reviewed-by: Felipe Morales <hel.sheep@gmail.com>
Reviewed-by: Scott Prager <splinterofchaos@gmail.com>
Reviewed-by: Michael Reed <m.reed@mykolab.com>

4 files changed, 68 insertions, 11 deletions

diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index e785dae714..08783ebbf3 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -1609,6 +1609,14 @@ A jump table for the options with a short description can be found at |Q_op|.
 		    completion in the preview window.  Only works in
 		    combination with "menu" or "menuone".
 
+	  noinsert  Do not insert any text for a match until the user selects
+		    a match from the menu. Only works in combination with
+		    "menu" or "menuone". No effect if "longest" is present.
+
+	  noselect  Do not select a match in the menu, force the user to
+		    select one from the menu. Only works in combination with
+		    "menu" or "menuone".
+
 
 						*'concealcursor'* *'cocu'*
 'concealcursor' 'cocu'	string (default: "")
diff --git a/src/nvim/edit.c b/src/nvim/edit.c
index 9704295aaa..d36168254a 100644
--- a/src/nvim/edit.c
+++ b/src/nvim/edit.c
@@ -154,6 +154,11 @@ static char_u     *compl_leader = NULL;
 static int compl_get_longest = FALSE;           /* put longest common string
                                                    in compl_leader */
 
+static int compl_no_insert = FALSE;             /* FALSE: select & insert
+                                                   TRUE: noinsert */
+static int compl_no_select = FALSE;             /* FALSE: select & insert
+                                                   TRUE: noselect */
+
 static int compl_used_match;            /* Selected one of the matches.  When
                                            FALSE the match was edited or using
                                            the longest common string. */
@@ -2972,8 +2977,19 @@ static int ins_compl_prep(int c)
   /* Set "compl_get_longest" when finding the first matches. */
   if (ctrl_x_mode == CTRL_X_NOT_DEFINED_YET
       || (ctrl_x_mode == 0 && !compl_started)) {
-    compl_get_longest = (vim_strchr(p_cot, 'l') != NULL);
+    compl_get_longest = (strstr((char *)p_cot, "longest") != NULL);
     compl_used_match = TRUE;
+
+    if (strstr((char *)p_cot, "noselect") != NULL) {
+      compl_no_insert = FALSE;
+      compl_no_select = TRUE;
+    } else if (strstr((char *)p_cot, "noinsert") != NULL) {
+      compl_no_insert = TRUE;
+      compl_no_select = FALSE;
+    } else {
+      compl_no_insert = FALSE;
+      compl_no_select = FALSE;
+    }
   }
 
   if (ctrl_x_mode == CTRL_X_NOT_DEFINED_YET) {
@@ -3875,6 +3891,7 @@ ins_compl_next (
   compl_T *found_compl = NULL;
   int found_end = FALSE;
   int advance;
+  int started = compl_started;
 
   /* When user complete function return -1 for findstart which is next
    * time of 'always', compl_shown_match become NULL. */
@@ -3945,7 +3962,7 @@ ins_compl_next (
         return -1;
       }
 
-      if (advance) {
+      if (!compl_no_select && advance) {
         if (compl_shows_dir == BACKWARD)
           --compl_pending;
         else
@@ -3990,13 +4007,18 @@ ins_compl_next (
   }
 
   /* Insert the text of the new completion, or the compl_leader. */
-  if (insert_match) {
-    if (!compl_get_longest || compl_used_match)
+  if (compl_no_insert && !started) {
+    ins_bytes(compl_orig_text + ins_compl_len());
+    compl_used_match = FALSE;
+  } else if (insert_match) {
+    if (!compl_get_longest || compl_used_match) {
       ins_compl_insert();
-    else
+    } else {
       ins_bytes(compl_leader + ins_compl_len());
-  } else
+    }
+  } else {
     compl_used_match = FALSE;
+  }
 
   if (!allow_get_expansion) {
     /* may undisplay the popup menu first */
@@ -4015,7 +4037,11 @@ ins_compl_next (
 
   /* Enter will select a match when the match wasn't inserted and the popup
    * menu is visible. */
-  compl_enter_selects = !insert_match && compl_match_array != NULL;
+  if (compl_no_insert && !started) {
+    compl_enter_selects = TRUE;
+  } else {
+    compl_enter_selects = !insert_match && compl_match_array != NULL;
+  }
 
   /*
    * Show the file name for the match (if any)
@@ -4082,7 +4108,7 @@ void ins_compl_check_keys(int frequency)
       }
     }
   }
-  if (compl_pending != 0 && !got_int) {
+  if (compl_pending != 0 && !got_int && !compl_no_insert) {
     int todo = compl_pending > 0 ? compl_pending : -compl_pending;
 
     compl_pending = 0;
diff --git a/src/nvim/option.c b/src/nvim/option.c
index 6fb661b6e2..a5ef6b6e7e 100644
--- a/src/nvim/option.c
+++ b/src/nvim/option.c
@@ -1705,7 +1705,8 @@ static char *(p_fdm_values[]) = {"manual", "expr", "marker", "indent", "syntax",
                                  "diff",
                                  NULL};
 static char *(p_fcl_values[]) = {"all", NULL};
-static char *(p_cot_values[]) = {"menu", "menuone", "longest", "preview", NULL};
+static char *(p_cot_values[]) = {"menu", "menuone", "longest", "preview",
+                                 "noinsert", "noselect", NULL};
 
 #ifdef INCLUDE_GENERATED_DECLARATIONS
 # include "option.c.generated.h"
diff --git a/test/functional/viml/completion_spec.lua b/test/functional/viml/completion_spec.lua
index df4018e707..2a02dd9cf0 100644
--- a/test/functional/viml/completion_spec.lua
+++ b/test/functional/viml/completion_spec.lua
@@ -3,12 +3,12 @@ local clear, feed, execute = helpers.clear, helpers.feed, helpers.execute
 local eval, eq, neq = helpers.eval, helpers.eq, helpers.neq
 local execute, source = helpers.execute, helpers.source
 
-describe("completion", function()
+describe('completion', function()
   before_each(function()
     clear()
   end)
 
-  describe("v:completed_item", function()
+  describe('v:completed_item', function()
     it('returns expected dict in normal completion', function()
       feed('ifoo<ESC>o<C-x><C-n><ESC>')
       eq('foo', eval('getline(2)'))
@@ -53,4 +53,26 @@ describe("completion", function()
         eval('v:completed_item'))
     end)
   end)
+  describe('completeopt', function()
+    it('inserts the first candidate if default', function()
+      execute('set completeopt+=menuone')
+      feed('ifoo<ESC>o<C-x><C-n>bar<ESC>')
+      eq('foobar', eval('getline(2)'))
+    end)
+    it('selects the first candidate if noinsert', function()
+      execute('set completeopt+=menuone,noinsert')
+      feed('ifoo<ESC>o<C-x><C-n><C-y><ESC>')
+      eq('foo', eval('getline(2)'))
+    end)
+    it('does not insert the first candidate if noselect', function()
+      execute('set completeopt+=menuone,noselect')
+      feed('ifoo<ESC>o<C-x><C-n>bar<ESC>')
+      eq('bar', eval('getline(2)'))
+    end)
+    it('does not select/insert the first candidate if noselect and noinsert', function()
+      execute('set completeopt+=menuone,noselect,noinsert')
+      feed('ifoo<ESC>o<C-x><C-n><ESC>')
+      eq('', eval('getline(2)'))
+    end)
+  end)
 end)