patch 8.1.0105: all tab stops are the samev8.1.0105

Problem:    All tab stops are the same.
Solution:   Add the variable tabstop feature. (Christian Brabandt,
            closes #2711)

31 files changed, 1751 insertions, 174 deletions

diff --git a/runtime/doc/change.txt b/runtime/doc/change.txt
index 05c18e64d3..b59f28f47b 100644
--- a/runtime/doc/change.txt
+++ b/runtime/doc/change.txt
@@ -987,6 +987,11 @@ This replaces each 'E' character with a euro sign.  Read more in |<Char->|.
 			this (that's a good habit anyway).
 			`:retab!` may also change a sequence of spaces by
 			<Tab> characters, which can mess up a printf().
+			If the |+vartabs| feature is enabled then a list of
+			tab widths separated by commas may be used in place of
+			a single tabstop.  Each value in the list represents
+			the width of one tabstop, except the final value which
+			applies to all following tabstops.
 			{not in Vi}
 
 							*retab-example*
diff --git a/runtime/doc/options.txt b/runtime/doc/options.txt
index d37fa641a4..65a9d17ea7 100644
--- a/runtime/doc/options.txt
+++ b/runtime/doc/options.txt
@@ -7172,6 +7172,10 @@ A jump table for the options with a short description can be found at |Q_op|.
 	set.
 	NOTE: This option is set to 0 when 'compatible' is set.
 
+	If Vim is compiled with the |+vartabs| feature then the value of
+	'softtabstop' will be ignored if |'varsofttabstop'| is set to
+	anything other than an empty string.
+
 						*'spell'* *'nospell'*
 'spell'			boolean	(default off)
 			local to window
@@ -7723,6 +7727,10 @@ A jump table for the options with a short description can be found at |Q_op|.
 	   though.  Otherwise aligned comments will be wrong when 'tabstop' is
 	   changed.
 
+	If Vim is compiled with the |+vartabs| feature then the value of
+	'tabstop' will be ignored if |'vartabstop'| is set to anything other
+	than an empty string.
+
 			*'tagbsearch'* *'tbs'* *'notagbsearch'* *'notbs'*
 'tagbsearch' 'tbs'	boolean	(default on)
 			global
@@ -8468,6 +8476,44 @@ A jump table for the options with a short description can be found at |Q_op|.
 	written to disk (see |crash-recovery|).  Also used for the
 	|CursorHold| autocommand event.
 
+					*'varsofttabstop'* *'vsts'*
+'varsofttabstop' 'vsts'	string	(default "")
+			local to buffer
+			{only available when compiled with the |+vartabs|
+			feature}
+			{not in Vi}
+	A list of the number of spaces that a <Tab> counts for while editing,
+	such as inserting a <Tab> or using <BS>.  It "feels" like variable-
+	width <Tab>s are being inserted, while in fact a mixture of spaces
+	and <Tab>s is used.  Tab widths are separated with commas, with the
+	final value applying to all subsequent tabs.
+
+	For example, when editing assembly language files where statements
+	start in the 8th column and comments in the 40th, it may be useful
+	to use the following: >
+		:set varsofttabstop=8,32,8
+<	This will set soft tabstops at the 8th and 40th columns, and at every
+	8th column thereafter.
+
+	Note that the value of |'softtabstop'| will be ignored while
+	'varsofttabstop' is set.
+
+						*'vartabstop'* *'vts'*
+'vartabstop' 'vts'	string	(default "")
+			local to buffer
+			{only available when compiled with the |+vartabs|
+			feature}
+			{not in Vi}
+	A list of the number of spaces that a <Tab> in the file counts for,
+	separated by commas.  Each value corresponds to one tab, with the
+	final value applying to all subsequent tabs. For example: >
+		:set vartabstop=4,20,10,8
+<	This will make the first tab 4 spaces wide, the second 20 spaces,
+	the third 10 spaces, and all following tabs 8 spaces.
+
+	Note that the value of |'tabstop'| will be ignored while 'vartabstop'
+	is set.
+
 						*'verbose'* *'vbs'*
 'verbose' 'vbs'		number	(default 0)
 			global
diff --git a/runtime/doc/various.txt b/runtime/doc/various.txt
index 7c8f3111c1..bd2b35ed74 100644
--- a/runtime/doc/various.txt
+++ b/runtime/doc/various.txt
@@ -453,6 +453,7 @@ N  *+timers*		the |timer_start()| function
 N  *+title*		Setting the window 'title' and 'icon'
 N  *+toolbar*		|gui-toolbar|
 N  *+user_commands*	User-defined commands. |user-commands|
+B  *+vartabs*		Variable-width tabstops. |'vartabstop'|
 N  *+viminfo*		|'viminfo'|
    *+vertsplit*		Vertically split windows |:vsplit|; Always enabled
 			since 8.0.1118.
diff --git a/runtime/optwin.vim b/runtime/optwin.vim
index cd1bea0cb2..5ab5792ae7 100644
--- a/runtime/optwin.vim
+++ b/runtime/optwin.vim
@@ -856,6 +856,14 @@ call <SID>OptionL("ts")
 call append("$", "shiftwidth\tnumber of spaces used for each step of (auto)indent")
 call append("$", "\t(local to buffer)")
 call <SID>OptionL("sw")
+if has("vartabs")
+  call append("$", "vartabstop\tlist of number of spaces a tab counts for")
+  call append("$", "\t(local to buffer)")
+  call <SID>OptionL("vts")
+  call append("$", "varsofttabstop\tlist of number of spaces a soft tabsstop counts for")
+  call append("$", "\t(local to buffer)")
+  call <SID>OptionL("vsts")
+endif
 call append("$", "smarttab\ta <Tab> in an indent inserts 'shiftwidth' spaces")
 call <SID>BinOptionG("sta", &sta)
 call append("$", "softtabstop\tif non-zero, number of spaces to insert for a <Tab>")
diff --git a/src/Makefile b/src/Makefile
index ca972547f6..e9a15a0cfa 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -2305,6 +2305,7 @@ test_arglist \
 	test_usercommands \
 	test_utf8 \
 	test_utf8_comparisons \
+	test_vartabs \
 	test_viminfo \
 	test_vimscript \
 	test_virtualedit \
diff --git a/src/beval.c b/src/beval.c
index 4ceddca19f..74750a27d0 100644
--- a/src/beval.c
+++ b/src/beval.c
@@ -124,6 +124,11 @@ get_beval_info(
 		*lnump = lnum;
 		*textp = lbuf;
 		*colp = col;
+#ifdef FEAT_VARTABS
+		if (beval->vts)
+		    vim_free(beval->vts);
+		beval->vts = tabstop_copy(wp->w_buffer->b_p_vts_array);
+#endif
 		beval->ts = wp->w_buffer->b_p_ts;
 		return OK;
 	    }
diff --git a/src/beval.h b/src/beval.h
index f4d1d80e9a..49ba05b2ec 100644
--- a/src/beval.h
+++ b/src/beval.h
@@ -71,7 +71,10 @@ typedef struct BalloonEvalStruct
     void		*clientData;	/* For callback */
 #endif
 
-    int			ts;		/* tabstop setting for this buffer */
+    int			ts;		// tabstop setting for this buffer
+#ifdef FEAT_VARTABS
+    int			*vts;		// vartabstop setting for this buffer
+#endif
     char_u		*msg;
 } BalloonEval;
 
diff --git a/src/buffer.c b/src/buffer.c
index 254aad461d..1f1833fc74 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -271,7 +271,7 @@ open_buffer(
     /*
      * Set/reset the Changed flag first, autocmds may change the buffer.
      * Apply the automatic commands, before processing the modelines.
-     * So the modelines have priority over auto commands.
+     * So the modelines have priority over autocommands.
      */
     /* When reading stdin, the buffer contents always needs writing, so set
      * the changed flag.  Unless in readonly mode: "ls | gview -".
@@ -2159,6 +2159,19 @@ free_buf_options(
     clear_string_option(&buf->b_p_fo);
     clear_string_option(&buf->b_p_flp);
     clear_string_option(&buf->b_p_isk);
+#ifdef FEAT_VARTABS
+    clear_string_option(&buf->b_p_vsts);
+    if (buf->b_p_vsts_nopaste)
+	vim_free(buf->b_p_vsts_nopaste);
+    buf->b_p_vsts_nopaste = NULL;
+    if (buf->b_p_vsts_array)
+	vim_free(buf->b_p_vsts_array);
+    buf->b_p_vsts_array = NULL;
+    clear_string_option(&buf->b_p_vts);
+    if (buf->b_p_vts_array)
+	vim_free(buf->b_p_vts_array);
+    buf->b_p_vts_array = NULL;
+#endif
 #ifdef FEAT_KEYMAP
     clear_string_option(&buf->b_p_keymap);
     keymap_clear(&buf->b_kmap_ga);
@@ -5190,7 +5203,7 @@ ex_buffer_all(exarg_T *eap)
 		win_close(wp, FALSE);
 		wpnext = firstwin;	/* just in case an autocommand does
 					   something strange with windows */
-		tpnext = first_tabpage;	/* start all over...*/
+		tpnext = first_tabpage;	/* start all over... */
 		open_wins = 0;
 	    }
 	    else
@@ -5650,8 +5663,8 @@ bt_prompt(buf_T *buf)
 }
 
 /*
- * Return TRUE if "buf" is a "nofile", "acwrite" or "terminal" buffer.
- * This means the buffer name is not a file name.
+ * Return TRUE if "buf" is a "nofile", "acwrite", "terminal" or "prompt"
+ * buffer.  This means the buffer name is not a file name.
  */
     int
 bt_nofile(buf_T *buf)
@@ -5663,7 +5676,8 @@ bt_nofile(buf_T *buf)
 }
 
 /*
- * Return TRUE if "buf" is a "nowrite", "nofile" or "terminal" buffer.
+ * Return TRUE if "buf" is a "nowrite", "nofile", "terminal" or "prompt"
+ * buffer.
  */
     int
 bt_dontwrite(buf_T *buf)
diff --git a/src/charset.c b/src/charset.c
index 179fc89db3..a4816887e4 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -812,7 +812,16 @@ vim_strnsize(char_u *s, int len)
  * Also see getvcol() below.
  */
 
-#define RET_WIN_BUF_CHARTABSIZE(wp, buf, p, col) \
+#ifdef FEAT_VARTABS
+# define RET_WIN_BUF_CHARTABSIZE(wp, buf, p, col) \
+    if (*(p) == TAB && (!(wp)->w_p_list || lcs_tab1)) \
+    { \
+	return tabstop_padding(col, (buf)->b_p_ts, (buf)->b_p_vts_array); \
+    } \
+    else \
+	return ptr2cells(p);
+#else
+# define RET_WIN_BUF_CHARTABSIZE(wp, buf, p, col) \
     if (*(p) == TAB && (!(wp)->w_p_list || lcs_tab1)) \
     { \
 	int ts; \
@@ -821,6 +830,7 @@ vim_strnsize(char_u *s, int len)
     } \
     else \
 	return ptr2cells(p);
+#endif
 
     int
 chartabsize(char_u *p, colnr_T col)
@@ -1221,8 +1231,13 @@ win_nolbr_chartabsize(
 
     if (*s == TAB && (!wp->w_p_list || lcs_tab1))
     {
+# ifdef FEAT_VARTABS
+	return tabstop_padding(col, wp->w_buffer->b_p_ts,
+				    wp->w_buffer->b_p_vts_array);
+# else
 	n = wp->w_buffer->b_p_ts;
 	return (int)(n - (col % n));
+# endif
     }
     n = ptr2cells(s);
     /* Add one cell for a double-width character in the last column of the
@@ -1282,6 +1297,9 @@ getvcol(
     char_u	*line;		/* start of the line */
     int		incr;
     int		head;
+#ifdef FEAT_VARTABS
+    int		*vts = wp->w_buffer->b_p_vts_array;
+#endif
     int		ts = wp->w_buffer->b_p_ts;
     int		c;
 
@@ -1332,7 +1350,11 @@ getvcol(
 	    }
 	    /* A tab gets expanded, depending on the current column */
 	    if (c == TAB)
+#ifdef FEAT_VARTABS
+		incr = tabstop_padding(vcol, ts, vts);
+#else
 		incr = ts - (vcol % ts);
+#endif
 	    else
 	    {
 #ifdef FEAT_MBYTE
diff --git a/src/edit.c b/src/edit.c
index 6a636b9e12..d4de825af1 100644
--- a/src/edit.c
+++ b/src/edit.c
@@ -742,7 +742,14 @@ edit(
 	    mincol = curwin->w_wcol;
 	    validate_cursor_col();
 
-	    if ((int)curwin->w_wcol < mincol - curbuf->b_p_ts
+	    if (
+#ifdef FEAT_VARTABS
+		(int)curwin->w_wcol < mincol - tabstop_at(
+					  get_nolist_virtcol(), curbuf->b_p_ts,
+							 curbuf->b_p_vts_array)
+#else
+		(int)curwin->w_wcol < mincol - curbuf->b_p_ts
+#endif
 		    && curwin->w_wrow == W_WINROW(curwin)
 						 + curwin->w_height - 1 - p_so
 		    && (curwin->w_cursor.lnum != curwin->w_topline
@@ -9329,23 +9336,31 @@ ins_bs(
 	 */
 	if (	   mode == BACKSPACE_CHAR
 		&& ((p_sta && in_indent)
-		    || (get_sts_value() != 0
+		    || ((get_sts_value() != 0
+#ifdef FEAT_VARTABS
+			|| tabstop_count(curbuf->b_p_vsts_array)
+#endif
+			)
 			&& curwin->w_cursor.col > 0
 			&& (*(ml_get_cursor() - 1) == TAB
 			    || (*(ml_get_cursor() - 1) == ' '
 				&& (!*inserted_space_p
 				    || arrow_used))))))
 	{
+#ifndef FEAT_VARTABS
 	    int		ts;
+#endif
 	    colnr_T	vcol;
 	    colnr_T	want_vcol;
 	    colnr_T	start_vcol;
 
 	    *inserted_space_p = FALSE;
+#ifndef FEAT_VARTABS
 	    if (p_sta && in_indent)
 		ts = (int)get_sw_value(curbuf);
 	    else
 		ts = (int)get_sts_value();
+#endif
 	    /* Compute the virtual column where we want to be.  Since
 	     * 'showbreak' may get in the way, need to get the last column of
 	     * the previous character. */
@@ -9354,7 +9369,15 @@ ins_bs(
 	    dec_cursor();
 	    getvcol(curwin, &curwin->w_cursor, NULL, NULL, &want_vcol);
 	    inc_cursor();
+#ifdef FEAT_VARTABS
+	    if (p_sta && in_indent)
+		want_vcol = (want_vcol / curbuf->b_p_sw) * curbuf->b_p_sw;
+	    else
+		want_vcol = tabstop_start(want_vcol, curbuf->b_p_sts,
+						     curbuf->b_p_vsts_array);
+#else
 	    want_vcol = (want_vcol / ts) * ts;
+#endif
 
 	    /* delete characters until we are at or before want_vcol */
 	    while (vcol > want_vcol
@@ -10144,10 +10167,22 @@ ins_tab(void)
 #endif
 
     /*
-     * When nothing special, insert TAB like a normal character
+     * When nothing special, insert TAB like a normal character.
      */
     if (!curbuf->b_p_et
+#ifdef FEAT_VARTABS
+	    && !(p_sta && ind
+		/* These five lines mean 'tabstop' != 'shiftwidth' */
+		&& ((tabstop_count(curbuf->b_p_vts_array) > 1)
+		    || (tabstop_count(curbuf->b_p_vts_array) == 1
+		        && tabstop_first(curbuf->b_p_vts_array)
+						       != get_sw_value(curbuf))
+	            || (tabstop_count(curbuf->b_p_vts_array) == 0
+		        && curbuf->b_p_ts != get_sw_value(curbuf))))
+	    && tabstop_count(curbuf->b_p_vsts_array) == 0
+#else
 	    && !(p_sta && ind && curbuf->b_p_ts != get_sw_value(curbuf))
+#endif
 	    && get_sts_value() == 0)
 	return TRUE;
 
@@ -10162,6 +10197,20 @@ ins_tab(void)
 #endif
     AppendToRedobuff((char_u *)"\t");
 
+#ifdef FEAT_VARTABS
+    if (p_sta && ind)		/* insert tab in indent, use 'shiftwidth' */
+    {
+	temp = (int)curbuf->b_p_sw;
+	temp -= get_nolist_virtcol() % temp;
+    }
+    else if (tabstop_count(curbuf->b_p_vsts_array) > 0 || curbuf->b_p_sts > 0)
+	                        /* use 'softtabstop' when set */
+	temp = tabstop_padding(get_nolist_virtcol(), curbuf->b_p_sts,
+						     curbuf->b_p_vsts_array);
+    else			/* otherwise use 'tabstop' */
+	temp = tabstop_padding(get_nolist_virtcol(), curbuf->b_p_ts,
+						     curbuf->b_p_vts_array);
+#else
     if (p_sta && ind)		/* insert tab in indent, use 'shiftwidth' */
 	temp = (int)get_sw_value(curbuf);
     else if (curbuf->b_p_sts != 0) /* use 'softtabstop' when set */
@@ -10169,6 +10218,7 @@ ins_tab(void)
     else			/* otherwise use 'tabstop' */
 	temp = (int)curbuf->b_p_ts;
     temp -= get_nolist_virtcol() % temp;
+#endif
 
     /*
      * Insert the first space with ins_char().	It will delete one char in
@@ -10193,7 +10243,13 @@ ins_tab(void)
     /*
      * When 'expandtab' not set: Replace spaces by TABs where possible.
      */
+#ifdef FEAT_VARTABS
+    if (!curbuf->b_p_et && (tabstop_count(curbuf->b_p_vsts_array) > 0
+                            || get_sts_value() > 0
+			    || (p_sta && ind)))
+#else
     if (!curbuf->b_p_et && (get_sts_value() || (p_sta && ind)))
+#endif
     {
 	char_u		*ptr;
 #ifdef FEAT_VREPLACE
diff --git a/src/evalfunc.c b/src/evalfunc.c
index 7325f5dfc5..0cd7527f77 100644
--- a/src/evalfunc.c
+++ b/src/evalfunc.c
@@ -6436,6 +6436,9 @@ f_has(typval_T *argvars, typval_T *rettv)
 	"user-commands",    /* was accidentally included in 5.4 */
 	"user_commands",
 #endif
+#ifdef FEAT_VARTABS
+	"vartabs",
+#endif
 #ifdef FEAT_VIMINFO
 	"viminfo",
 #endif
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index 60d72023c9..53334342c1 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -673,12 +673,17 @@ ex_retab(exarg_T *eap)
     long	vcol;
     long	start_col = 0;		/* For start of white-space string */
     long	start_vcol = 0;		/* For start of white-space string */
-    int		temp;
     long	old_len;
     char_u	*ptr;
     char_u	*new_line = (char_u *)1;    /* init to non-NULL */
     int		did_undo;		/* called u_save for current line */
+#ifdef FEAT_VARTABS
+    int		*new_ts = 0;
+    char_u	*new_ts_str;		/* string value of tab argument */
+#else
+    int		temp;
     int		new_ts;
+#endif
     int		save_list;
     linenr_T	first_line = 0;		/* first changed line */
     linenr_T	last_line = 0;		/* last changed line */
@@ -686,6 +691,23 @@ ex_retab(exarg_T *eap)
     save_list = curwin->w_p_list;
     curwin->w_p_list = 0;	    /* don't want list mode here */
 
+#ifdef FEAT_VARTABS
+    new_ts_str = eap->arg;
+    if (!tabstop_set(eap->arg, &new_ts))
+	return;
+    while (vim_isdigit(*(eap->arg)) || *(eap->arg) == ',')
+	++(eap->arg);
+
+    // This ensures that either new_ts and new_ts_str are freshly allocated,
+    // or new_ts points to an existing array and new_ts_str is null.
+    if (new_ts == 0)
+    {
+	new_ts = curbuf->b_p_vts_array;
+	new_ts_str = NULL;
+    }
+    else
+	new_ts_str = vim_strnsave(new_ts_str, eap->arg - new_ts_str);
+#else
     new_ts = getdigits(&(eap->arg));
     if (new_ts < 0)
     {
@@ -694,6 +716,7 @@ ex_retab(exarg_T *eap)
     }
     if (new_ts == 0)
 	new_ts = curbuf->b_p_ts;
+#endif
     for (lnum = eap->line1; !got_int && lnum <= eap->line2; ++lnum)
     {
 	ptr = ml_get(lnum);
@@ -726,6 +749,16 @@ ex_retab(exarg_T *eap)
 		    num_tabs = 0;
 		    if (!curbuf->b_p_et)
 		    {
+#ifdef FEAT_VARTABS
+			int t, s;
+
+			tabstop_fromto(start_vcol, vcol,
+				       tabstop_count(new_ts)? 0: curbuf->b_p_ts,
+				       new_ts,
+				       &t, &s);
+			num_tabs = t;
+			num_spaces = s;
+#else
 			temp = new_ts - (start_vcol % new_ts);
 			if (num_spaces >= temp)
 			{
@@ -734,6 +767,7 @@ ex_retab(exarg_T *eap)
 			}
 			num_tabs += num_spaces / new_ts;
 			num_spaces -= (num_spaces / new_ts) * new_ts;
+#endif
 		    }
 		    if (curbuf->b_p_et || got_tab ||
 					(num_spaces + num_tabs < len))
@@ -791,14 +825,53 @@ ex_retab(exarg_T *eap)
     if (got_int)
 	EMSG(_(e_interr));
 
+#ifdef FEAT_VARTABS
+    // If a single value was given then it can be considered equal to
+    // either the value of 'tabstop' or the value of 'vartabstop'.
+    if (tabstop_count(curbuf->b_p_vts_array) == 0
+	&& tabstop_count(new_ts) == 1
+	&& curbuf->b_p_ts == tabstop_first(new_ts))
+	; /* not changed */
+    else if (tabstop_count(curbuf->b_p_vts_array) > 0
+        && tabstop_eq(curbuf->b_p_vts_array, new_ts))
+	; /* not changed */
+    else
+	redraw_curbuf_later(NOT_VALID);
+#else
     if (curbuf->b_p_ts != new_ts)
 	redraw_curbuf_later(NOT_VALID);
+#endif
     if (first_line != 0)
 	changed_lines(first_line, 0, last_line + 1, 0L);
 
     curwin->w_p_list = save_list;	/* restore 'list' */
 
+#ifdef FEAT_VARTABS
+    if (new_ts_str != NULL)		/* set the new tabstop */
+    {
+	// If 'vartabstop' is in use or if the value given to retab has more
+	// than one tabstop then update 'vartabstop'.
+	int *old_vts_ary = curbuf->b_p_vts_array;
+
+	if (tabstop_count(old_vts_ary) > 0 || tabstop_count(new_ts) > 1)
+	{
+	    set_string_option_direct((char_u *)"vts", -1, new_ts_str,
+							OPT_FREE|OPT_LOCAL, 0);
+	    vim_free(new_ts_str);
+	    curbuf->b_p_vts_array = new_ts;
+	    vim_free(old_vts_ary);
+	}
+	else
+	{
+	    // 'vartabstop' wasn't in use and a single value was given to
+	    // retab then update 'tabstop'.
+	    curbuf->b_p_ts = tabstop_first(new_ts);
+	    vim_free(new_ts);
+	}
+    }
+#else
     curbuf->b_p_ts = new_ts;
+#endif
     coladvance(curwin->w_curswant);
 
     u_clearline();
diff --git a/src/feature.h b/src/feature.h
index 5b915b838c..762a70cee7 100644
--- a/src/feature.h
+++ b/src/feature.h
@@ -806,6 +806,13 @@
 #endif
 
 /*
+ * +vartabs		'vartabstop' and 'varsofttabstop' options.
+ */
+#ifdef FEAT_BIG
+# define FEAT_VARTABS
+#endif
+
+/*
  * Preferences:
  * ============
  */
diff --git a/src/gui_beval.c b/src/gui_beval.c
index 8c1cd9696f..7e4625080f 100644
--- a/src/gui_beval.c
+++ b/src/gui_beval.c
@@ -130,6 +130,9 @@ gui_mch_create_beval_area(
 	beval->msg = mesg;
 	beval->msgCB = mesgCB;
 	beval->clientData = clientData;
+#ifdef FEAT_VARTABS
+	beval->vts = NULL;
+#endif
 
 	/*
 	 * Set up event handler which will keep its eyes on the pointer,
@@ -172,6 +175,10 @@ gui_mch_destroy_beval_area(BalloonEval *beval)
 # else
     XtDestroyWidget(beval->balloonShell);
 # endif
+# ifdef FEAT_VARTABS
+    if (beval->vts)
+	vim_free(beval->vts);
+# endif
     vim_free(beval);
 }
 #endif
diff --git a/src/gui_w32.c b/src/gui_w32.c
index 49aa1e0bd2..855381108b 100644
--- a/src/gui_w32.c
+++ b/src/gui_w32.c
@@ -8934,6 +8934,9 @@ gui_mch_create_beval_area(
 	beval->msg = mesg;
 	beval->msgCB = mesgCB;
 	beval->clientData = clientData;
+#ifdef FEAT_VARTABS
+	beval->vts = NULL;
+#endif
 
 	InitCommonControls();
 	cur_beval = beval;
@@ -8990,6 +8993,10 @@ TrackUserActivity(UINT uMsg)
     void
 gui_mch_destroy_beval_area(BalloonEval *beval)
 {
+#ifdef FEAT_VARTABS
+    if (beval->vts)
+	vim_free(beval->vts);
+#endif
     vim_free(beval);
 }
 #endif /* FEAT_BEVAL_GUI */
diff --git a/src/hardcopy.c b/src/hardcopy.c
index 420ceb7638..44e9d4fe84 100644
--- a/src/hardcopy.c
+++ b/src/hardcopy.c
@@ -915,7 +915,12 @@ hardcopy_line(
 	if (line[col] == TAB || tab_spaces != 0)
 	{
 	    if (tab_spaces == 0)
+#ifdef FEAT_VARTABS
+		tab_spaces = tabstop_padding(print_pos, curbuf->b_p_ts,
+							curbuf->b_p_vts_array);
+#else
 		tab_spaces = (int)(curbuf->b_p_ts - (print_pos % curbuf->b_p_ts));
+#endif
 
 	    while (tab_spaces > 0)
 	    {
diff --git a/src/message.c b/src/message.c
index fd087a4a79..4dac5ae04d 100644
--- a/src/message.c
+++ b/src/message.c
@@ -1831,7 +1831,12 @@ msg_prt_line(char_u *s, int list)
 	    if (c == TAB && (!list || lcs_tab1))
 	    {
 		/* tab amount depends on current column */
+#ifdef FEAT_VARTABS
+		n_extra = tabstop_padding(col, curbuf->b_p_ts,
+						    curbuf->b_p_vts_array) - 1;
+#else
 		n_extra = curbuf->b_p_ts - col % curbuf->b_p_ts - 1;
+#endif
 		if (!list)
 		{
 		    c = ' ';
diff --git a/src/misc1.c b/src/misc1.c
index d797a0bc65..5242ca5729 100644
--- a/src/misc1.c
+++ b/src/misc1.c
@@ -36,7 +36,12 @@ static garray_T	ga_users;
     int
 get_indent(void)
 {
+#ifdef FEAT_VARTABS
+    return get_indent_str_vtab(ml_get_curline(), (int)curbuf->b_p_ts,
+						 curbuf->b_p_vts_array, FALSE);
+#else
     return get_indent_str(ml_get_curline(), (int)curbuf->b_p_ts, FALSE);
+#endif
 }
 
 /*
@@ -45,7 +50,12 @@ get_indent(void)
     int
 get_indent_lnum(linenr_T lnum)
 {
+#ifdef FEAT_VARTABS
+    return get_indent_str_vtab(ml_get(lnum), (int)curbuf->b_p_ts,
+						 curbuf->b_p_vts_array, FALSE);
+#else
     return get_indent_str(ml_get(lnum), (int)curbuf->b_p_ts, FALSE);
+#endif
 }
 
 #if defined(FEAT_FOLDING) || defined(PROTO)
@@ -56,7 +66,12 @@ get_indent_lnum(linenr_T lnum)
     int
 get_indent_buf(buf_T *buf, linenr_T lnum)
 {
+#ifdef FEAT_VARTABS
+    return get_indent_str_vtab(ml_get_buf(buf, lnum, FALSE),
+			       (int)curbuf->b_p_ts, buf->b_p_vts_array, FALSE);
+#else
     return get_indent_str(ml_get_buf(buf, lnum, FALSE), (int)buf->b_p_ts, FALSE);
+#endif
 }
 #endif
 
@@ -91,6 +106,37 @@ get_indent_str(
     return count;
 }
 
+#ifdef FEAT_VARTABS
+/*
+ * Count the size (in window cells) of the indent in line "ptr", using
+ * variable tabstops.
+ * if "list" is TRUE, count only screen size for tabs.
+ */
+    int
+get_indent_str_vtab(char_u *ptr, int ts, int *vts, int list)
+{
+    int		count = 0;
+
+    for ( ; *ptr; ++ptr)
+    {
+	if (*ptr == TAB)    /* count a tab for what it is worth */
+	{
+	    if (!list || lcs_tab1)
+		count += tabstop_padding(count, ts, vts);
+	    else
+		/* In list mode, when tab is not set, count screen char width
+		 * for Tab, displays: ^I */
+		count += ptr2cells(ptr);
+	}
+	else if (*ptr == ' ')
+	    ++count;		/* count a space for one */
+	else
+	    break;
+    }
+    return count;
+}
+#endif
+
 /*
  * Set the indent of the current line.
  * Leaves the cursor on the first non-blank in the line.
@@ -115,6 +161,9 @@ set_indent(
     int		line_len;
     int		doit = FALSE;
     int		ind_done = 0;	    /* measured in spaces */
+#ifdef FEAT_VARTABS
+    int		ind_col = 0;
+#endif
     int		tab_pad;
     int		retval = FALSE;
     int		orig_char_len = -1; /* number of initial whitespace chars when
@@ -147,8 +196,13 @@ set_indent(
 	    {
 		if (*p == TAB)
 		{
+#ifdef FEAT_VARTABS
+		    tab_pad = tabstop_padding(ind_done, curbuf->b_p_ts,
+							curbuf->b_p_vts_array);
+#else
 		    tab_pad = (int)curbuf->b_p_ts
 					   - (ind_done % (int)curbuf->b_p_ts);
+#endif
 		    /* stop if this tab will overshoot the target */
 		    if (todo < tab_pad)
 			break;
@@ -165,23 +219,51 @@ set_indent(
 		++p;
 	    }
 
+#ifdef FEAT_VARTABS
+	    /* These diverge from this point. */
+	    ind_col = ind_done;
+#endif
 	    /* Set initial number of whitespace chars to copy if we are
 	     * preserving indent but expandtab is set */
 	    if (curbuf->b_p_et)
 		orig_char_len = ind_len;
 
 	    /* Fill to next tabstop with a tab, if possible */
+#ifdef FEAT_VARTABS
+	    tab_pad = tabstop_padding(ind_done, curbuf->b_p_ts,
+						curbuf->b_p_vts_array);
+#else
 	    tab_pad = (int)curbuf->b_p_ts - (ind_done % (int)curbuf->b_p_ts);
+#endif
 	    if (todo >= tab_pad && orig_char_len == -1)
 	    {
 		doit = TRUE;
 		todo -= tab_pad;
 		++ind_len;
 		/* ind_done += tab_pad; */
+#ifdef FEAT_VARTABS
+		ind_col += tab_pad;
+#endif
 	    }
 	}
 
 	/* count tabs required for indent */
+#ifdef FEAT_VARTABS
+	for (;;)
+	{
+	    tab_pad = tabstop_padding(ind_col, curbuf->b_p_ts,
+							curbuf->b_p_vts_array);
+	    if (todo < tab_pad)
+		break;
+	    if (*p != TAB)
+		doit = TRUE;
+	    else
+		++p;
+	    todo -= tab_pad;
+	    ++ind_len;
+	    ind_col += tab_pad;
+	}
+#else
 	while (todo >= (int)curbuf->b_p_ts)
 	{
 	    if (*p != TAB)
@@ -192,6 +274,7 @@ set_indent(
 	    ++ind_len;
 	    /* ind_done += (int)curbuf->b_p_ts; */
 	}
+#endif
     }
     /* count spaces required for indent */
     while (todo > 0)
@@ -266,8 +349,13 @@ set_indent(
 	    {
 		if (*p == TAB)
 		{
+#ifdef FEAT_VARTABS
+		    tab_pad = tabstop_padding(ind_done, curbuf->b_p_ts,
+							curbuf->b_p_vts_array);
+#else
 		    tab_pad = (int)curbuf->b_p_ts
 					   - (ind_done % (int)curbuf->b_p_ts);
+#endif
 		    /* stop if this tab will overshoot the target */
 		    if (todo < tab_pad)
 			break;
@@ -283,21 +371,42 @@ set_indent(
 	    }
 
 	    /* Fill to next tabstop with a tab, if possible */
+#ifdef FEAT_VARTABS
+	    tab_pad = tabstop_padding(ind_done, curbuf->b_p_ts,
+						curbuf->b_p_vts_array);
+#else
 	    tab_pad = (int)curbuf->b_p_ts - (ind_done % (int)curbuf->b_p_ts);
+#endif
 	    if (todo >= tab_pad)
 	    {
 		*s++ = TAB;
 		todo -= tab_pad;
+#ifdef FEAT_VARTABS
+		ind_done += tab_p