feat: cmdline funcs (#18284)

vim-patch:8.2.4903: cannot get the current cmdline completion type and position

Problem:    Cannot get the current cmdline completion type and position.
Solution:   Add getcmdcompltype() and getcmdscreenpos(). (Shougo Matsushita,
            closes vim/vim#10344)
https://github.com/vim/vim/commit/79d599b8772022af1d657f368c2fc97aa342c0da

vim-patch:8.2.4910: imperfect coding

Problem:    Imperfect coding.
Solution:   Make code nicer.
https://github.com/vim/vim/commit/9ff7d717aa3176de5c61de340deb93f41c7780fc

6 files changed, 82 insertions, 1 deletions

diff --git a/runtime/doc/builtin.txt b/runtime/doc/builtin.txt
index a909fd0d6b..b9954dc99c 100644
--- a/runtime/doc/builtin.txt
+++ b/runtime/doc/builtin.txt
@@ -179,8 +179,12 @@ getcharmod()			Number	modifiers for the last typed character
 getcharpos({expr})		List	position of cursor, mark, etc.
 getcharsearch()			Dict	last character search
 getcharstr([expr])		String	get one character from the user
+getcmdcompltype()		String	return the type of the current
+					command-line completion
 getcmdline()			String	return the current command-line
 getcmdpos()			Number	return cursor position in command-line
+getcmdscreenpos()		Number	return cursor screen position in
+					command-line
 getcmdtype()			String	return current command-line type
 getcmdwintype()			String	return current command-line window type
 getcompletion({pat}, {type} [, {filtered}])
@@ -2792,6 +2796,13 @@ getcharstr([expr])					*getcharstr()*
 		Otherwise this works like |getchar()|, except that a number
 		result is converted to a string.
 
+getcmdcompltype()					*getcmdcompltype()*
+		Return the type of the current command-line completion.
+		Only works when the command line is being edited, thus
+		requires use of |c_CTRL-\_e| or |c_CTRL-R_=|.
+		See |command-completion| for the return string.
+		Also see |getcmdtype()|, |setcmdpos()| and |getcmdline()|.
+		Returns an empty string when completion is not defined.
 
 getcmdline()						*getcmdline()*
 		Return the current command-line.  Only works when the command
@@ -2811,6 +2822,15 @@ getcmdpos()						*getcmdpos()*
 		Returns 0 otherwise.
 		Also see |getcmdtype()|, |setcmdpos()| and |getcmdline()|.
 
+getcmdscreenpos()					*getcmdscreenpos()*
+		Return the screen position of the cursor in the command line
+		as a byte count.  The first column is 1.
+		Instead of |getcmdpos()|, it adds the prompt position.
+		Only works when editing the command line, thus requires use of
+		|c_CTRL-\_e| or |c_CTRL-R_=| or an expression mapping.
+		Returns 0 otherwise.
+		Also see |getcmdpos()|, |setcmdpos()|.
+
 getcmdtype()						*getcmdtype()*
 		Return the current command-line type. Possible return values
 		are:
diff --git a/runtime/doc/usr_41.txt b/runtime/doc/usr_41.txt
index ff69b8f224..60bcadd582 100644
--- a/runtime/doc/usr_41.txt
+++ b/runtime/doc/usr_41.txt
@@ -855,8 +855,12 @@ Buffers, windows and the argument list:
 	swapname()		get the swap file path of a buffer
 
 Command line:					*command-line-functions*
+	getcmdcompltype()	get the type of the current command line
+				completion
 	getcmdline()		get the current command line
 	getcmdpos()		get position of the cursor in the command line
+	getcmdscreenpos()	get screen position of the cursor in the
+				command line
 	setcmdpos()		set position of the cursor in the command line
 	getcmdtype()		return the current command-line type
 	getcmdwintype()		return the current command-line window type
diff --git a/src/nvim/eval.lua b/src/nvim/eval.lua
index 698cffe2fa..d7a17d6e15 100644
--- a/src/nvim/eval.lua
+++ b/src/nvim/eval.lua
@@ -152,8 +152,10 @@ return {
     getcharpos={args=1, base=1},
     getcharsearch={},
     getcharstr={args={0, 1}},
+    getcmdcompltype={},
     getcmdline={},
     getcmdpos={},
+    getcmdscreenpos={},
     getcmdtype={},
     getcmdwintype={},
     getcompletion={args={2, 3}, base=1},
diff --git a/src/nvim/eval/funcs.c b/src/nvim/eval/funcs.c
index be43c3010a..7946ed75e1 100644
--- a/src/nvim/eval/funcs.c
+++ b/src/nvim/eval/funcs.c
@@ -3175,6 +3175,13 @@ static void f_getcharsearch(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   tv_dict_add_nr(dict, S_LEN("until"), last_csearch_until());
 }
 
+/// "getcmdcompltype()" function
+static void f_getcmdcompltype(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  rettv->v_type = VAR_STRING;
+  rettv->vval.v_string = (char *)get_cmdline_completion();
+}
+
 /// "getcmdline()" function
 static void f_getcmdline(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
@@ -3188,6 +3195,12 @@ static void f_getcmdpos(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   rettv->vval.v_number = get_cmdline_pos() + 1;
 }
 
+/// "getcmdscreenpos()" function
+static void f_getcmdscreenpos(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+  rettv->vval.v_number = get_cmdline_screen_pos() + 1;
+}
+
 /// "getcmdtype()" function
 static void f_getcmdtype(typval_T *argvars, typval_T *rettv, FunPtr fptr)
 {
diff --git a/src/nvim/ex_getln.c b/src/nvim/ex_getln.c
index d4cea15d20..771e84651f 100644
--- a/src/nvim/ex_getln.c
+++ b/src/nvim/ex_getln.c
@@ -4683,7 +4683,7 @@ char_u *addstar(char_u *fname, size_t len, int context)
  *  EXPAND_ENV_VARS         Complete environment variable names
  *  EXPAND_USER             Complete user names
  */
-static void set_expand_context(expand_T *xp)
+void set_expand_context(expand_T *xp)
 {
   // only expansion for ':', '>' and '=' command-lines
   if (ccline.cmdfirstc != ':'
@@ -5949,6 +5949,25 @@ static struct cmdline_info *get_ccline_ptr(void)
   }
 }
 
+/// Get the current command-line completion type.
+char_u *get_cmdline_completion(void)
+{
+  if (cmdline_star > 0) {
+    return NULL;
+  }
+  struct cmdline_info *p = get_ccline_ptr();
+
+  if (p != NULL && p->xpc != NULL) {
+    set_expand_context(p->xpc);
+    char_u *cmd_compl = get_user_cmd_complete(p->xpc, p->xpc->xp_context);
+    if (cmd_compl != NULL) {
+      return vim_strsave(cmd_compl);
+    }
+  }
+
+  return NULL;
+}
+
 /*
  * Get the current command line in allocated memory.
  * Only works when the command line is being edited.
@@ -5983,6 +6002,17 @@ int get_cmdline_pos(void)
   return p->cmdpos;
 }
 
+/// Get the command line cursor screen position.
+int get_cmdline_screen_pos(void)
+{
+  struct cmdline_info *p = get_ccline_ptr();
+
+  if (p == NULL) {
+    return -1;
+  }
+  return p->cmdspos;
+}
+
 /*
  * Set the command line byte position to "pos".  Zero is the first position.
  * Only works when the command line is being edited.
diff --git a/src/nvim/testdir/test_cmdline.vim b/src/nvim/testdir/test_cmdline.vim
index 5c2f6f8d0b..759caac878 100644
--- a/src/nvim/testdir/test_cmdline.vim
+++ b/src/nvim/testdir/test_cmdline.vim
@@ -1212,4 +1212,16 @@ func Test_recalling_cmdline()
   cunmap <Plug>(save-cmdline)
 endfunc
 
+func Check_completion()
+  call assert_equal('let a', getcmdline())
+  call assert_equal(6, getcmdpos())
+  call assert_equal(7, getcmdscreenpos())
+  call assert_equal('var', getcmdcompltype())
+  return ''
+endfunc
+
+func Test_screenpos_and_completion()
+  call feedkeys(":let a\<C-R>=Check_completion()\<CR>\<Esc>", "xt")
+endfunc
+
 " vim: shiftwidth=2 sts=2 expandtab