vim-patch:8.1.0519: cannot save and restore the tag stack

Problem:    Cannot save and restore the tag stack.
Solution:   Add gettagstack() and settagstack(). (Yegappan Lakshmanan,
            closes vim/vim#3604)
f49cc60aa8

runtime/doc/eval.txt

@@ -2112,6 +2112,7 @@ gettabvar({nr}, {varname} [, {def}])
 				any	variable {varname} in tab {nr} or {def}
 gettabwinvar({tabnr}, {winnr}, {name} [, {def}])
 				any	{name} in {winnr} in tab page {tabnr}
+gettagstack([{nr}])		Dict	get the tag stack of window {nr}
 getwininfo([{winid}])		List	list of windows
 getwinpos([{timeout}])		List	X and Y coord in pixels of the Vim window
 getwinposx()			Number	X coord in pixels of GUI Vim window
@@ -2277,6 +2278,8 @@ setreg({n}, {v}[, {opt}])	Number	set register to value and type
 settabvar({nr}, {varname}, {val})	set {varname} in tab page {nr} to {val}
 settabwinvar({tabnr}, {winnr}, {varname}, {val})    set {varname} in window
 					{winnr} in tab page {tabnr} to {val}
+settagstack({nr}, {dict} [, {action}])
+				Number	modify tag stack using {dict}
 setwinvar({nr}, {varname}, {val})	set {varname} in window {nr} to {val}
 sha256({string})		String	SHA256 checksum of {string}
 shellescape({string} [, {special}])
@@ -4550,6 +4553,34 @@ gettabwinvar({tabnr}, {winnr}, {varname} [, {def}])		*gettabwinvar()*
 		To obtain all window-local variables use: >
 			gettabwinvar({tabnr}, {winnr}, '&')
 
+gettagstack([{nr}])					*gettagstack()*
+		The result is a Dict, which is the tag stack of window {nr}.
+		{nr} can be the window number or the |window-ID|.
+		When {nr} is not specified, the current window is used.
+		When window {nr} doesn't exist, an empty Dict is returned.
+
+		The returned dictionary contains the following entries:
+			curidx		Current index in the stack. When at
+					top of the stack, set to (length + 1).
+					Index of bottom of the stack is 1.
+			items		List of items in the stack. Each item
+					is a dictionary containing the
+					entries described below.
+			length		Number of entries in the stack.
+
+		Each item in the stack is a dictionary with the following
+		entries:
+			bufnr		buffer number of the current jump
+			from		cursor position before the tag jump.
+					See |getpos()| for the format of the
+					returned list.
+			matchnr		current matching tag number. Used when
+					multiple matching tags are found for a
+					name.
+			tagname		name of the tag
+
+		See |tagstack| for more information about the tag stack.
+
 							*getwinposx()*
 getwinposx()	The result is a Number, which is the X coordinate in pixels of
 		the left hand side of the GUI Vim window.  The result will be
@@ -7181,6 +7212,38 @@ settabwinvar({tabnr}, {winnr}, {varname}, {val})	*settabwinvar()*
 			:call settabwinvar(3, 2, "myvar", "foobar")
 <		This function is not available in the |sandbox|.
 
+settagstack({nr}, {dict} [, {action}])			*settagstack()*
+		Modify the tag stack of the window {nr} using {dict}.
+		{nr} can be the window number or the |window-ID|.
+
+		For a list of supported items in {dict}, refer to
+		|gettagstack()|
+							*E962*
+		If {action} is not present or is set to 'r', then the tag
+		stack is replaced. If {action} is set to 'a', then new entries
+		from {dict} are pushed onto the tag stack.
+
+		Returns zero for success, -1 for failure.
+
+		Examples:
+		    Set current index of the tag stack to 4: >
+			call settagstack(1005, {'curidx' : 4})
+
+<		    Empty the tag stack of window 3: >
+			call settagstack(3, {'items' : []})
+
+<		    Push a new item onto the tag stack: >
+			let pos = [bufnr('myfile.txt'), 10, 1, 0]
+			let newtag = [{'tagname' : 'mytag', 'from' : pos}]
+			call settagstack(2, {'items' : newtag}, 'a')
+
+<		    Save and restore the tag stack: >
+			let stack = gettagstack(1003)
+			" do something else
+			call settagstack(1003, stack)
+			unlet stack
+<
+
 setwinvar({nr}, {varname}, {val})			*setwinvar()*
 		Like |settabwinvar()| for the current tab page.
 		Examples: >

runtime/doc/tagsrch.txt

@@ -173,6 +173,9 @@ commands explained above the tag stack will look like this:
    1  1 main		1  harddisk2:text/vim/test
    2  1 FuncB	       59  harddisk2:text/vim/src/main.c
 
+The gettagstack() function returns the tag stack of a specified window. The
+settagstack() function modifies the tag stack of a window.
+
 							*E73*
 When you try to use the tag stack while it doesn't contain anything you will
 get an error message.

runtime/doc/usr_41.txt

@@ -957,6 +957,8 @@ Various:					*various-functions*
 
 	taglist()		get list of matching tags
 	tagfiles()		get a list of tags files
+	gettagstack()		get the tag stack
+	settagstack()		modify the tag stack
 
 	luaeval()		evaluate Lua expression
 	py3eval()		evaluate Python expression (|+python3|)

src/nvim/eval.c

@@ -10404,6 +10404,26 @@ static void f_gettabwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   getwinvar(argvars, rettv, 1);
 }
 
+/*
+ * "gettagstack()" function
+ */
+    static void
+f_gettagstack(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+    win_T	*wp = curwin;			// default is current window
+
+    tv_dict_alloc_ret(rettv);
+
+    if (argvars[0].v_type != VAR_UNKNOWN)
+    {
+	wp = find_win_by_nr_or_id(&argvars[0]);
+	if (wp == NULL)
+	    return;
+    }
+
+    get_tagstack(wp, rettv->vval.v_dict);
+}
+
 /// Returns information about a window as a dictionary.
 static dict_T *get_win_info(win_T *wp, int16_t tpnr, int16_t winnr)
 {
@@ -15196,6 +15216,64 @@ static void f_settabwinvar(typval_T *argvars, typval_T *rettv, FunPtr fptr)
   setwinvar(argvars, rettv, 1);
 }
 
+/*
+ * "settagstack()" function
+ */
+    static void
+f_settagstack(typval_T *argvars, typval_T *rettv, FunPtr fptr)
+{
+    static char *e_invact2 = N_("E962: Invalid action: '%s'");
+    win_T	*wp;
+    dict_T	*d;
+    int		action = 'r';
+
+    rettv->vval.v_number = -1;
+
+    // first argument: window number or id
+    wp = find_win_by_nr_or_id(&argvars[0]);
+    if (wp == NULL)
+	return;
+
+    // second argument: dict with items to set in the tag stack
+    if (argvars[1].v_type != VAR_DICT)
+    {
+	EMSG(_(e_dictreq));
+	return;
+    }
+    d = argvars[1].vval.v_dict;
+    if (d == NULL)
+	return;
+
+    // third argument: action - 'a' for append and 'r' for replace.
+    // default is to replace the stack.
+    if (argvars[2].v_type == VAR_UNKNOWN)
+	action = 'r';
+    else if (argvars[2].v_type == VAR_STRING)
+    {
+	const char *actstr;
+	actstr = tv_get_string_chk(&argvars[2]);
+	if (actstr == NULL)
+	    return;
+	if ((*actstr == 'r' || *actstr == 'a') && actstr[1] == NUL)
+	    action = *actstr;
+	else
+	{
+	    EMSG2(_(e_invact2), actstr);
+	    return;
+	}
+    }
+    else
+    {
+	EMSG(_(e_stringreq));
+	return;
+    }
+
+    if (set_tagstack(wp, d, action) == OK)
+	rettv->vval.v_number = 0;
+    else
+	EMSG(_(e_listreq));
+}
+
 /*
  * "setwinvar()" function
  */
@@ -18197,7 +18275,7 @@ pos_T *var2fpos(const typval_T *const tv, const int dollar_lnum,
  * Return FAIL when conversion is not possible, doesn't check the position for
  * validity.
  */
-static int list2fpos(typval_T *arg, pos_T *posp, int *fnump, colnr_T *curswantp)
+int list2fpos(typval_T *arg, pos_T *posp, int *fnump, colnr_T *curswantp)
 {
   list_T *l;
   long i = 0;

src/nvim/eval.lua

@@ -142,6 +142,7 @@ return {
     gettabinfo={args={0, 1}},
     gettabvar={args={2, 3}},
     gettabwinvar={args={3, 4}},
+    gettagstack={args={0, 1}},
     getwininfo={args={0, 1}},
     getwinposx={},
     getwinposy={},
@@ -268,6 +269,7 @@ return {
     setreg={args={2, 3}},
     settabvar={args=3},
     settabwinvar={args=4},
+    settagstack={args={2, 3}},
     setwinvar={args=3},
     sha256={args=1},
     shellescape={args={1, 2}},

src/nvim/tag.c

@@ -2863,3 +2863,202 @@ int get_tags(list_T *list, char_u *pat, char_u *buf_fname)
   }
   return ret;
 }
+
+/*
+ * Return information about 'tag' in dict 'retdict'.
+ */
+    static void
+get_tag_details(taggy_T *tag, dict_T *retdict)
+{
+    list_T	*pos;
+    fmark_T	*fmark;
+
+    tv_dict_add_str(retdict, S_LEN("tagname"), (const char *)tag->tagname);
+    tv_dict_add_nr(retdict, S_LEN("matchnr"), tag->cur_match + 1);
+    tv_dict_add_nr(retdict, S_LEN("bufnr"), tag->cur_fnum);
+
+    if ((pos = tv_list_alloc(4)) == NULL)
+	return;
+    tv_dict_add_list(retdict, S_LEN("from"), pos);
+
+    fmark = &tag->fmark;
+    tv_list_append_number(pos,
+			(varnumber_T)(fmark->fnum != -1 ? fmark->fnum : 0));
+    tv_list_append_number(pos, (varnumber_T)fmark->mark.lnum);
+    tv_list_append_number(pos, (varnumber_T)(fmark->mark.col == MAXCOL ?
+					MAXCOL : fmark->mark.col + 1));
+    tv_list_append_number(pos, (varnumber_T)fmark->mark.coladd);
+}
+
+/*
+ * Return the tag stack entries of the specified window 'wp' in dictionary
+ * 'retdict'.
+ */
+    void
+get_tagstack(win_T *wp, dict_T *retdict)
+{
+    list_T	*l;
+    int		i;
+    dict_T	*d;
+
+    tv_dict_add_nr(retdict, S_LEN("length"), wp->w_tagstacklen);
+    tv_dict_add_nr(retdict, S_LEN("curidx"), wp->w_tagstackidx + 1);
+    l = tv_list_alloc(2);
+    if (l == NULL)
+	return;
+    tv_dict_add_list(retdict, S_LEN("items"), l);
+
+    for (i = 0; i < wp->w_tagstacklen; i++)
+    {
+	if ((d = tv_dict_alloc()) == NULL)
+	    return;
+	tv_list_append_dict(l, d);
+
+	get_tag_details(&wp->w_tagstack[i], d);
+    }
+}
+
+/*
+ * Free all the entries in the tag stack of the specified window
+ */
+    static void
+tagstack_clear(win_T *wp)
+{
+    int i;
+
+    // Free the current tag stack
+    for (i = 0; i < wp->w_tagstacklen; ++i)
+	xfree(wp->w_tagstack[i].tagname);
+    wp->w_tagstacklen = 0;
+    wp->w_tagstackidx = 0;
+}
+
+/*
+ * Remove the oldest entry from the tag stack and shift the rest of
+ * the entires to free up the top of the stack.
+ */
+    static void
+tagstack_shift(win_T *wp)
+{
+    taggy_T	*tagstack = wp->w_tagstack;
+    int		i;
+
+    xfree(tagstack[0].tagname);
+    for (i = 1; i < wp->w_tagstacklen; ++i)
+	tagstack[i - 1] = tagstack[i];
+    wp->w_tagstacklen--;
+}
+
+/*
+ * Push a new item to the tag stack
+ */
+    static void
+tagstack_push_item(
+	win_T	*wp,
+	char_u	*tagname,
+	int	cur_fnum,
+	int	cur_match,
+	pos_T	mark,
+	int	fnum)
+{
+    taggy_T	*tagstack = wp->w_tagstack;
+    int		idx = wp->w_tagstacklen;	// top of the stack
+
+    // if the tagstack is full: remove the oldest entry
+    if (idx >= TAGSTACKSIZE)
+    {
+	tagstack_shift(wp);
+	idx = TAGSTACKSIZE - 1;
+    }
+
+    wp->w_tagstacklen++;
+    tagstack[idx].tagname = tagname;
+    tagstack[idx].cur_fnum = cur_fnum;
+    tagstack[idx].cur_match = cur_match;
+    if (tagstack[idx].cur_match < 0)
+	tagstack[idx].cur_match = 0;
+    tagstack[idx].fmark.mark = mark;
+    tagstack[idx].fmark.fnum = fnum;
+}
+
+/*
+ * Add a list of items to the tag stack in the specified window
+ */
+    static void
+tagstack_push_items(win_T *wp, list_T *l)
+{
+    listitem_T	*li;
+    dictitem_T	*di;
+    dict_T	*itemdict;
+    char_u	*tagname;
+    pos_T	mark;
+    int		fnum;
+
+    // Add one entry at a time to the tag stack
+    for (li = l->lv_first; li != NULL; li = li->li_next)
+    {
+	if (li->li_tv.v_type != VAR_DICT || li->li_tv.vval.v_dict == NULL)
+	    continue;				// Skip non-dict items
+	itemdict = li->li_tv.vval.v_dict;
+
+	// parse 'from' for the cursor position before the tag jump
+	if ((di = tv_dict_find(itemdict, "from", -1)) == NULL)
+	    continue;
+	if (list2fpos(&di->di_tv, &mark, &fnum, NULL) != OK)
+	    continue;
+	if ((tagname = (char_u *)
+		tv_dict_get_string(itemdict, "tagname", TRUE)) == NULL)
+	    continue;
+
+	if (mark.col > 0)
+	    mark.col--;
+	tagstack_push_item(wp, tagname,
+		(int)tv_dict_get_number(itemdict, "bufnr"),
+		(int)tv_dict_get_number(itemdict, "matchnr") - 1,
+		mark, fnum);
+    }
+}
+
+/*
+ * Set the current index in the tag stack. Valid values are between 0
+ * and the stack length (inclusive).
+ */
+    static void
+tagstack_set_curidx(win_T *wp, int curidx)
+{
+    wp->w_tagstackidx = curidx;
+    if (wp->w_tagstackidx < 0)			// sanity check
+	wp->w_tagstackidx = 0;
+    if (wp->w_tagstackidx > wp->w_tagstacklen)
+	wp->w_tagstackidx = wp->w_tagstacklen;
+}
+
+/*
+ * Set the tag stack entries of the specified window.
+ * 'action' is set to either 'a' for append or 'r' for replace.
+ */
+    int
+set_tagstack(win_T *wp, dict_T *d, int action)
+{
+    dictitem_T	*di;
+    list_T	*l;
+
+    if ((di = tv_dict_find(d, "items", -1)) != NULL)
+    {
+	if (di->di_tv.v_type != VAR_LIST)
+	{
+	    return FAIL;
+	}
+	l = di->di_tv.vval.v_list;
+
+	if (action == 'r')
+	    tagstack_clear(wp);
+
+	tagstack_push_items(wp, l);
+    }
+
+    if ((di = tv_dict_find(d, "curidx", -1)) != NULL)
+	tagstack_set_curidx(wp, (int)tv_get_number(&di->di_tv) - 1);
+
+    return OK;
+}

src/nvim/testdir/test_tagjump.vim

@@ -258,6 +258,107 @@ func Test_tagjump_etags()
   bwipe!
 endfunc
 
+" Test for getting and modifying the tag stack
+func Test_getsettagstack()
+  call writefile(['line1', 'line2', 'line3'], 'Xfile1')
+  call writefile(['line1', 'line2', 'line3'], 'Xfile2')
+  call writefile(['line1', 'line2', 'line3'], 'Xfile3')
+
+  enew | only
+  call settagstack(1, {'items' : []})
+  call assert_equal(0, gettagstack(1).length)
+  call assert_equal([], gettagstack(1).items)
+  " Error cases
+  call assert_equal({}, gettagstack(100))
+  call assert_equal(-1, settagstack(100, {'items' : []}))
+  call assert_fails('call settagstack(1, [1, 10])', 'E715')
+  call assert_fails("call settagstack(1, {'items' : 10})", 'E714')
+  call assert_fails("call settagstack(1, {'items' : []}, 10)", 'E928')
+  call assert_fails("call settagstack(1, {'items' : []}, 'b')", 'E962')
+
+  set tags=Xtags
+  call writefile(["!_TAG_FILE_ENCODING\tutf-8\t//",
+        \ "one\tXfile1\t1",
+        \ "three\tXfile3\t3",
+        \ "two\tXfile2\t2"],
+        \ 'Xtags')
+
+  let stk = []
+  call add(stk, {'bufnr' : bufnr('%'), 'tagname' : 'one',
+	\ 'from' : [bufnr('%'), line('.'), col('.'), 0], 'matchnr' : 1})
+  tag one
+  call add(stk, {'bufnr' : bufnr('%'), 'tagname' : 'two',
+	\ 'from' : [bufnr('%'), line('.'), col('.'), 0], 'matchnr' : 1})
+  tag two
+  call add(stk, {'bufnr' : bufnr('%'), 'tagname' : 'three',
+	\ 'from' : [bufnr('%'), line('.'), col('.'), 0], 'matchnr' : 1})
+  tag three
+  call assert_equal(3, gettagstack(1).length)
+  call assert_equal(stk, gettagstack(1).items)
+  " Check for default - current window
+  call assert_equal(3, gettagstack().length)
+  call assert_equal(stk, gettagstack().items)
+
+  " Try to set current index to invalid values
+  call settagstack(1, {'curidx' : -1})
+  call assert_equal(1, gettagstack().curidx)
+  call settagstack(1, {'curidx' : 50})
+  call assert_equal(4, gettagstack().curidx)
+
+  " Try pushing invalid items onto the stack
+  call settagstack(1, {'items' : []})
+  call settagstack(1, {'items' : ["plate"]}, 'a')
+  call assert_equal(0, gettagstack().length)
+  call assert_equal([], gettagstack().items)
+  call settagstack(1, {'items' : [{"tagname" : "abc"}]}, 'a')
+  call assert_equal(0, gettagstack().length)
+  call assert_equal([], gettagstack().items)
+  call settagstack(1, {'items' : [{"from" : 100}]}, 'a')
+  call assert_equal(0, gettagstack().length)
+  call assert_equal([], gettagstack().items)
+  call settagstack(1, {'items' : [{"from" : [2, 1, 0, 0]}]}, 'a')
+  call assert_equal(0, gettagstack().length)
+  call assert_equal([], gettagstack().items)
+
+  " Push one item at a time to the stack
+  call settagstack(1, {'items' : []})
+  call settagstack(1, {'items' : [stk[0]]}, 'a')
+  call settagstack(1, {'items' : [stk[1]]}, 'a')
+  call settagstack(1, {'items' : [stk[2]]}, 'a')
+  call settagstack(1, {'curidx' : 4})
+  call assert_equal({'length' : 3, 'curidx' : 4, 'items' : stk},
+        \ gettagstack(1))
+
+  " Try pushing items onto a full stack
+  for i in range(7)
+    call settagstack(1, {'items' : stk}, 'a')
+  endfor
+  call assert_equal(20, gettagstack().length)
+  call settagstack(1,
+        \ {'items' : [{'tagname' : 'abc', 'from' : [1, 10, 1, 0]}]}, 'a')
+  call assert_equal('abc', gettagstack().items[19].tagname)
+
+  " Tag with multiple matches
+  call writefile(["!_TAG_FILE_ENCODING\tutf-8\t//",
+        \ "two\tXfile1\t1",
+        \ "two\tXfile2\t3",
+        \ "two\tXfile3\t2"],
+        \ 'Xtags')
+  call settagstack(1, {'items' : []})
+  tag two
+  tnext
+  tnext
+  call assert_equal(1, gettagstack().length)
+  call assert_equal(3, gettagstack().items[0].matchnr)
+
+  call settagstack(1, {'items' : []})
+  call delete('Xfile1')
+  call delete('Xfile2')
+  call delete('Xfile3')
+  call delete('Xtags')
+  set tags&
+endfunc
+
 func Test_tag_with_count()
   call writefile([
 	\ 'test	Xtest.h	/^void test();$/;"	p	typeref:typename:void	signature:()',