new file mode 100644
--- /dev/null
+++ b/src/evalbuffer.c
@@ -0,0 +1,887 @@
+/* vi:set ts=8 sts=4 sw=4 noet:
+ *
+ * VIM - Vi IMproved	by Bram Moolenaar
+ *
+ * Do ":help uganda"  in Vim to read copying and usage conditions.
+ * Do ":help credits" in Vim to see a list of people who contributed.
+ * See README.txt for an overview of the Vim source code.
+ */
+
+/*
+ * evalbuffer.c: Buffer related builtin functions
+ */
+
+#include "vim.h"
+
+#if defined(FEAT_EVAL) || defined(PROTO)
+/*
+ * Mark references in functions of buffers.
+ */
+    int
+set_ref_in_buffers(int copyID)
+{
+    int		abort = FALSE;
+    buf_T	*bp;
+
+    FOR_ALL_BUFFERS(bp)
+    {
+	listener_T *lnr;
+	typval_T tv;
+
+	for (lnr = bp->b_listener; !abort && lnr != NULL; lnr = lnr->lr_next)
+	{
+	    if (lnr->lr_callback.cb_partial != NULL)
+	    {
+		tv.v_type = VAR_PARTIAL;
+		tv.vval.v_partial = lnr->lr_callback.cb_partial;
+		abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
+	    }
+	}
+# ifdef FEAT_JOB_CHANNEL
+	if (!abort && bp->b_prompt_callback.cb_partial != NULL)
+	{
+	    tv.v_type = VAR_PARTIAL;
+	    tv.vval.v_partial = bp->b_prompt_callback.cb_partial;
+	    abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
+	}
+	if (!abort && bp->b_prompt_interrupt.cb_partial != NULL)
+	{
+	    tv.v_type = VAR_PARTIAL;
+	    tv.vval.v_partial = bp->b_prompt_interrupt.cb_partial;
+	    abort = abort || set_ref_in_item(&tv, copyID, NULL, NULL);
+	}
+# endif
+	if (abort)
+	    break;
+    }
+    return abort;
+}
+
+    buf_T *
+buflist_find_by_name(char_u *name, int curtab_only)
+{
+    int		save_magic;
+    char_u	*save_cpo;
+    buf_T	*buf;
+
+    // Ignore 'magic' and 'cpoptions' here to make scripts portable
+    save_magic = p_magic;
+    p_magic = TRUE;
+    save_cpo = p_cpo;
+    p_cpo = (char_u *)"";
+
+    buf = buflist_findnr(buflist_findpat(name, name + STRLEN(name),
+						    TRUE, FALSE, curtab_only));
+
+    p_magic = save_magic;
+    p_cpo = save_cpo;
+    return buf;
+}
+
+/*
+ * Find a buffer by number or exact name.
+ */
+    buf_T *
+find_buffer(typval_T *avar)
+{
+    buf_T	*buf = NULL;
+
+    if (avar->v_type == VAR_NUMBER)
+	buf = buflist_findnr((int)avar->vval.v_number);
+    else if (avar->v_type == VAR_STRING && avar->vval.v_string != NULL)
+    {
+	buf = buflist_findname_exp(avar->vval.v_string);
+	if (buf == NULL)
+	{
+	    // No full path name match, try a match with a URL or a "nofile"
+	    // buffer, these don't use the full path.
+	    FOR_ALL_BUFFERS(buf)
+		if (buf->b_fname != NULL
+			&& (path_with_url(buf->b_fname)
+#ifdef FEAT_QUICKFIX
+			    || bt_nofilename(buf)
+#endif
+			   )
+			&& STRCMP(buf->b_fname, avar->vval.v_string) == 0)
+		    break;
+	}
+    }
+    return buf;
+}
+
+/*
+ * If there is a window for "curbuf", make it the current window.
+ */
+    static void
+find_win_for_curbuf(void)
+{
+    wininfo_T *wip;
+
+    for (wip = curbuf->b_wininfo; wip != NULL; wip = wip->wi_next)
+    {
+	if (wip->wi_win != NULL)
+	{
+	    curwin = wip->wi_win;
+	    break;
+	}
+    }
+}
+
+/*
+ * Set line or list of lines in buffer "buf".
+ */
+    static void
+set_buffer_lines(
+	buf_T	    *buf,
+	linenr_T    lnum_arg,
+	int	    append,
+	typval_T    *lines,
+	typval_T    *rettv)
+{
+    linenr_T    lnum = lnum_arg + (append ? 1 : 0);
+    char_u	*line = NULL;
+    list_T	*l = NULL;
+    listitem_T	*li = NULL;
+    long	added = 0;
+    linenr_T	append_lnum;
+    buf_T	*curbuf_save = NULL;
+    win_T	*curwin_save = NULL;
+    int		is_curbuf = buf == curbuf;
+
+    // When using the current buffer ml_mfp will be set if needed.  Useful when
+    // setline() is used on startup.  For other buffers the buffer must be
+    // loaded.
+    if (buf == NULL || (!is_curbuf && buf->b_ml.ml_mfp == NULL) || lnum < 1)
+    {
+	rettv->vval.v_number = 1;	// FAIL
+	return;
+    }
+
+    if (!is_curbuf)
+    {
+	curbuf_save = curbuf;
+	curwin_save = curwin;
+	curbuf = buf;
+	find_win_for_curbuf();
+    }
+
+    if (append)
+	// appendbufline() uses the line number below which we insert
+	append_lnum = lnum - 1;
+    else
+	// setbufline() uses the line number above which we insert, we only
+	// append if it's below the last line
+	append_lnum = curbuf->b_ml.ml_line_count;
+
+    if (lines->v_type == VAR_LIST)
+    {
+	l = lines->vval.v_list;
+	li = l->lv_first;
+    }
+    else
+	line = tv_get_string_chk(lines);
+
+    // default result is zero == OK
+    for (;;)
+    {
+	if (l != NULL)
+	{
+	    // list argument, get next string
+	    if (li == NULL)
+		break;
+	    line = tv_get_string_chk(&li->li_tv);
+	    li = li->li_next;
+	}
+
+	rettv->vval.v_number = 1;	// FAIL
+	if (line == NULL || lnum > curbuf->b_ml.ml_line_count + 1)
+	    break;
+
+	// When coming here from Insert mode, sync undo, so that this can be
+	// undone separately from what was previously inserted.
+	if (u_sync_once == 2)
+	{
+	    u_sync_once = 1; // notify that u_sync() was called
+	    u_sync(TRUE);
+	}
+
+	if (!append && lnum <= curbuf->b_ml.ml_line_count)
+	{
+	    // Existing line, replace it.
+	    // Removes any existing text properties.
+	    if (u_savesub(lnum) == OK && ml_replace_len(
+		      lnum, line, (colnr_T)STRLEN(line) + 1, TRUE, TRUE) == OK)
+	    {
+		changed_bytes(lnum, 0);
+		if (is_curbuf && lnum == curwin->w_cursor.lnum)
+		    check_cursor_col();
+		rettv->vval.v_number = 0;	// OK
+	    }
+	}
+	else if (added > 0 || u_save(lnum - 1, lnum) == OK)
+	{
+	    // append the line
+	    ++added;
+	    if (ml_append(lnum - 1, line, (colnr_T)0, FALSE) == OK)
+		rettv->vval.v_number = 0;	// OK
+	}
+
+	if (l == NULL)			// only one string argument
+	    break;
+	++lnum;
+    }
+
+    if (added > 0)
+    {
+	win_T	    *wp;
+	tabpage_T   *tp;
+
+	appended_lines_mark(append_lnum, added);
+
+	// Only adjust the cursor for buffers other than the current, unless it
+	// is the current window.  For curbuf and other windows it has been
+	// done in mark_adjust_internal().
+	FOR_ALL_TAB_WINDOWS(tp, wp)
+	    if (wp->w_buffer == buf
+		    && (wp->w_buffer != curbuf || wp == curwin)
+		    && wp->w_cursor.lnum > append_lnum)
+		wp->w_cursor.lnum += added;
+	check_cursor_col();
+	update_topline();
+    }
+
+    if (!is_curbuf)
+    {
+	curbuf = curbuf_save;
+	curwin = curwin_save;
+    }
+}
+
+/*
+ * "append(lnum, string/list)" function
+ */
+    void
+f_append(typval_T *argvars, typval_T *rettv)
+{
+    linenr_T	lnum = tv_get_lnum(&argvars[0]);
+
+    set_buffer_lines(curbuf, lnum, TRUE, &argvars[1], rettv);
+}
+
+/*
+ * "appendbufline(buf, lnum, string/list)" function
+ */
+    void
+f_appendbufline(typval_T *argvars, typval_T *rettv)
+{
+    linenr_T	lnum;
+    buf_T	*buf;
+
+    buf = tv_get_buf(&argvars[0], FALSE);
+    if (buf == NULL)
+	rettv->vval.v_number = 1; // FAIL
+    else
+    {
+	lnum = tv_get_lnum_buf(&argvars[1], buf);
+	set_buffer_lines(buf, lnum, TRUE, &argvars[2], rettv);
+    }
+}
+
+/*
+ * "bufadd(expr)" function
+ */
+    void
+f_bufadd(typval_T *argvars, typval_T *rettv)
+{
+    char_u *name = tv_get_string(&argvars[0]);
+
+    rettv->vval.v_number = buflist_add(*name == NUL ? NULL : name, 0);
+}
+
+/*
+ * "bufexists(expr)" function
+ */
+    void
+f_bufexists(typval_T *argvars, typval_T *rettv)
+{
+    rettv->vval.v_number = (find_buffer(&argvars[0]) != NULL);
+}
+
+/*
+ * "buflisted(expr)" function
+ */
+    void
+f_buflisted(typval_T *argvars, typval_T *rettv)
+{
+    buf_T	*buf;
+
+    buf = find_buffer(&argvars[0]);
+    rettv->vval.v_number = (buf != NULL && buf->b_p_bl);
+}
+
+/*
+ * "bufload(expr)" function
+ */
+    void
+f_bufload(typval_T *argvars, typval_T *rettv UNUSED)
+{
+    buf_T	*buf = get_buf_arg(&argvars[0]);
+
+    if (buf != NULL)
+	buffer_ensure_loaded(buf);
+}
+
+/*
+ * "bufloaded(expr)" function
+ */
+    void
+f_bufloaded(typval_T *argvars, typval_T *rettv)
+{
+    buf_T	*buf;
+
+    buf = find_buffer(&argvars[0]);
+    rettv->vval.v_number = (buf != NULL && buf->b_ml.ml_mfp != NULL);
+}
+
+/*
+ * "bufname(expr)" function
+ */
+    void
+f_bufname(typval_T *argvars, typval_T *rettv)
+{
+    buf_T	*buf;
+
+    if (argvars[0].v_type == VAR_UNKNOWN)
+	buf = curbuf;
+    else
+    {
+	(void)tv_get_number(&argvars[0]);	// issue errmsg if type error
+	++emsg_off;
+	buf = tv_get_buf(&argvars[0], FALSE);
+	--emsg_off;
+    }
+    rettv->v_type = VAR_STRING;
+    if (buf != NULL && buf->b_fname != NULL)
+	rettv->vval.v_string = vim_strsave(buf->b_fname);
+    else
+	rettv->vval.v_string = NULL;
+}
+
+/*
+ * "bufnr(expr)" function
+ */
+    void
+f_bufnr(typval_T *argvars, typval_T *rettv)
+{
+    buf_T	*buf;
+    int		error = FALSE;
+    char_u	*name;
+
+    if (argvars[0].v_type == VAR_UNKNOWN)
+	buf = curbuf;
+    else
+    {
+	(void)tv_get_number(&argvars[0]);    // issue errmsg if type error
+	++emsg_off;
+	buf = tv_get_buf(&argvars[0], FALSE);
+	--emsg_off;
+    }
+
+    // If the buffer isn't found and the second argument is not zero create a
+    // new buffer.
+    if (buf == NULL
+	    && argvars[1].v_type != VAR_UNKNOWN
+	    && tv_get_number_chk(&argvars[1], &error) != 0
+	    && !error
+	    && (name = tv_get_string_chk(&argvars[0])) != NULL
+	    && !error)
+	buf = buflist_new(name, NULL, (linenr_T)1, 0);
+
+    if (buf != NULL)
+	rettv->vval.v_number = buf->b_fnum;
+    else
+	rettv->vval.v_number = -1;
+}
+
+    static void
+buf_win_common(typval_T *argvars, typval_T *rettv, int get_nr)
+{
+    win_T	*wp;
+    int		winnr = 0;
+    buf_T	*buf;
+
+    (void)tv_get_number(&argvars[0]);	    // issue errmsg if type error
+    ++emsg_off;
+    buf = tv_get_buf(&argvars[0], TRUE);
+    FOR_ALL_WINDOWS(wp)
+    {
+	++winnr;
+	if (wp->w_buffer == buf)
+	    break;
+    }
+    rettv->vval.v_number = (wp != NULL ? (get_nr ? winnr : wp->w_id) : -1);
+    --emsg_off;
+}
+
+/*
+ * "bufwinid(nr)" function
+ */
+    void
+f_bufwinid(typval_T *argvars, typval_T *rettv)
+{
+    buf_win_common(argvars, rettv, FALSE);
+}
+
+/*
+ * "bufwinnr(nr)" function
+ */
+    void
+f_bufwinnr(typval_T *argvars, typval_T *rettv)
+{
+    buf_win_common(argvars, rettv, TRUE);
+}
+
+/*
+ * "deletebufline()" function
+ */
+    void
+f_deletebufline(typval_T *argvars, typval_T *rettv)
+{
+    buf_T	*buf;
+    linenr_T	first, last;
+    linenr_T	lnum;
+    long	count;
+    int		is_curbuf;
+    buf_T	*curbuf_save = NULL;
+    win_T	*curwin_save = NULL;
+    tabpage_T	*tp;
+    win_T	*wp;
+
+    buf = tv_get_buf(&argvars[0], FALSE);
+    if (buf == NULL)
+    {
+	rettv->vval.v_number = 1; // FAIL
+	return;
+    }
+    is_curbuf = buf == curbuf;
+
+    first = tv_get_lnum_buf(&argvars[1], buf);
+    if (argvars[2].v_type != VAR_UNKNOWN)
+	last = tv_get_lnum_buf(&argvars[2], buf);
+    else
+	last = first;
+
+    if (buf->b_ml.ml_mfp == NULL || first < 1
+			   || first > buf->b_ml.ml_line_count || last < first)
+    {
+	rettv->vval.v_number = 1;	// FAIL
+	return;
+    }
+
+    if (!is_curbuf)
+    {
+	curbuf_save = curbuf;
+	curwin_save = curwin;
+	curbuf = buf;
+	find_win_for_curbuf();
+    }
+    if (last > curbuf->b_ml.ml_line_count)
+	last = curbuf->b_ml.ml_line_count;
+    count = last - first + 1;
+
+    // When coming here from Insert mode, sync undo, so that this can be
+    // undone separately from what was previously inserted.
+    if (u_sync_once == 2)
+    {
+	u_sync_once = 1; // notify that u_sync() was called
+	u_sync(TRUE);
+    }
+
+    if (u_save(first - 1, last + 1) == FAIL)
+    {
+	rettv->vval.v_number = 1;	// FAIL
+	return;
+    }
+
+    for (lnum = first; lnum <= last; ++lnum)
+	ml_delete(first, TRUE);
+
+    FOR_ALL_TAB_WINDOWS(tp, wp)
+	if (wp->w_buffer == buf)
+	{
+	    if (wp->w_cursor.lnum > last)
+		wp->w_cursor.lnum -= count;
+	    else if (wp->w_cursor.lnum> first)
+		wp->w_cursor.lnum = first;
+	    if (wp->w_cursor.lnum > wp->w_buffer->b_ml.ml_line_count)
+		wp->w_cursor.lnum = wp->w_buffer->b_ml.ml_line_count;
+	}
+    check_cursor_col();
+    deleted_lines_mark(first, count);
+
+    if (!is_curbuf)
+    {
+	curbuf = curbuf_save;
+	curwin = curwin_save;
+    }
+}
+
+/*
+ * Returns buffer options, variables and other attributes in a dictionary.
+ */
+    static dict_T *
+get_buffer_info(buf_T *buf)
+{
+    dict_T	*dict;
+    tabpage_T	*tp;
+    win_T	*wp;
+    list_T	*windows;
+
+    dict = dict_alloc();
+    if (dict == NULL)
+	return NULL;
+
+    dict_add_number(dict, "bufnr", buf->b_fnum);
+    dict_add_string(dict, "name", buf->b_ffname);
+    dict_add_number(dict, "lnum", buf == curbuf ? curwin->w_cursor.lnum
+						     : buflist_findlnum(buf));
+    dict_add_number(dict, "loaded", buf->b_ml.ml_mfp != NULL);
+    dict_add_number(dict, "listed", buf->b_p_bl);
+    dict_add_number(dict, "changed", bufIsChanged(buf));
+    dict_add_number(dict, "changedtick", CHANGEDTICK(buf));
+    dict_add_number(dict, "hidden",
+			    buf->b_ml.ml_mfp != NULL && buf->b_nwindows == 0);
+
+    // Get a reference to buffer variables
+    dict_add_dict(dict, "variables", buf->b_vars);
+
+    // List of windows displaying this buffer
+    windows = list_alloc();
+    if (windows != NULL)
+    {
+	FOR_ALL_TAB_WINDOWS(tp, wp)
+	    if (wp->w_buffer == buf)
+		list_append_number(windows, (varnumber_T)wp->w_id);
+	dict_add_list(dict, "windows", windows);
+    }
+
+#ifdef FEAT_TEXT_PROP
+    // List of popup windows displaying this buffer
+    windows = list_alloc();
+    if (windows != NULL)
+    {
+	for (wp = first_popupwin; wp != NULL; wp = wp->w_next)
+	    if (wp->w_buffer == buf)
+		list_append_number(windows, (varnumber_T)wp->w_id);
+	FOR_ALL_TABPAGES(tp)
+	    for (wp = tp->tp_first_popupwin; wp != NULL; wp = wp->w_next)
+		if (wp->w_buffer == buf)
+		    list_append_number(windows, (varnumber_T)wp->w_id);
+
+	dict_add_list(dict, "popups", windows);
+    }
+#endif
+
+#ifdef FEAT_SIGNS
+    if (buf->b_signlist != NULL)
+    {
+	// List of signs placed in this buffer
+	list_T	*signs = list_alloc();
+	if (signs != NULL)
+	{
+	    get_buffer_signs(buf, signs);
+	    dict_add_list(dict, "signs", signs);
+	}
+    }
+#endif
+
+    return dict;
+}
+
+/*
+ * "getbufinfo()" function
+ */
+    void
+f_getbufinfo(typval_T *argvars, typval_T *rettv)
+{
+    buf_T	*buf = NULL;
+    buf_T	*argbuf = NULL;
+    dict_T	*d;
+    int		filtered = FALSE;
+    int		sel_buflisted = FALSE;
+    int		sel_bufloaded = FALSE;
+    int		sel_bufmodified = FALSE;
+
+    if (rettv_list_alloc(rettv) != OK)
+	return;
+
+    // List of all the buffers or selected buffers
+    if (argvars[0].v_type == VAR_DICT)
+    {
+	dict_T	*sel_d = argvars[0].vval.v_dict;
+
+	if (sel_d != NULL)
+	{
+	    dictitem_T	*di;
+
+	    filtered = TRUE;
+
+	    di = dict_find(sel_d, (char_u *)"buflisted", -1);
+	    if (di != NULL && tv_get_number(&di->di_tv))
+		sel_buflisted = TRUE;
+
+	    di = dict_find(sel_d, (char_u *)"bufloaded", -1);
+	    if (di != NULL && tv_get_number(&di->di_tv))
+		sel_bufloaded = TRUE;
+
+	    di = dict_find(sel_d, (char_u *)"bufmodified", -1);
+	    if (di != NULL && tv_get_number(&di->di_tv))
+		sel_bufmodified = TRUE;
+	}
+    }
+    else if (argvars[0].v_type != VAR_UNKNOWN)
+    {
+	// Information about one buffer.  Argument specifies the buffer
+	(void)tv_get_number(&argvars[0]);   // issue errmsg if type error
+	++emsg_off;
+	argbuf = tv_get_buf(&argvars[0], FALSE);
+	--emsg_off;
+	if (argbuf == NULL)
+	    return;
+    }
+
+    // Return information about all the buffers or a specified buffer
+    FOR_ALL_BUFFERS(buf)
+    {
+	if (argbuf != NULL && argbuf != buf)
+	    continue;
+	if (filtered && ((sel_bufloaded && buf->b_ml.ml_mfp == NULL)
+			|| (sel_buflisted && !buf->b_p_bl)
+			|| (sel_bufmodified && !buf->b_changed)))
+	    continue;
+
+	d = get_buffer_info(buf);
+	if (d != NULL)
+	    list_append_dict(rettv->vval.v_list, d);
+	if (argbuf != NULL)
+	    return;
+    }
+}
+
+/*
+ * Get line or list of lines from buffer "buf" into "rettv".
+ * Return a range (from start to end) of lines in rettv from the specified
+ * buffer.
+ * If 'retlist' is TRUE, then the lines are returned as a Vim List.
+ */
+    static void
+get_buffer_lines(
+    buf_T	*buf,
+    linenr_T	start,
+    linenr_T	end,
+    int		retlist,
+    typval_T	*rettv)
+{
+    char_u	*p;
+
+    rettv->v_type = VAR_STRING;
+    rettv->vval.v_string = NULL;
+    if (retlist && rettv_list_alloc(rettv) == FAIL)
+	return;
+
+    if (buf == NULL || buf->b_ml.ml_mfp == NULL || start < 0)
+	return;
+
+    if (!retlist)
+    {
+	if (start >= 1 && start <= buf->b_ml.ml_line_count)
+	    p = ml_get_buf(buf, start, FALSE);
+	else
+	    p = (char_u *)"";
+	rettv->vval.v_string = vim_strsave(p);
+    }
+    else
+    {
+	if (end < start)
+	    return;
+
+	if (start < 1)
+	    start = 1;
+	if (end > buf->b_ml.ml_line_count)
+	    end = buf->b_ml.ml_line_count;
+	while (start <= end)
+	    if (list_append_string(rettv->vval.v_list,
+				 ml_get_buf(buf, start++, FALSE), -1) == FAIL)
+		break;
+    }
+}
+
+/*
+ * "getbufline()" function
+ */
+    void
+f_getbufline(typval_T *argvars, typval_T *rettv)
+{
+    linenr_T	lnum;
+    linenr_T	end;
+    buf_T	*buf;
+
+    (void)tv_get_number(&argvars[0]);	    // issue errmsg if type error
+    ++emsg_off;
+    buf = tv_get_buf(&argvars[0], FALSE);
+    --emsg_off;
+
+    lnum = tv_get_lnum_buf(&argvars[1], buf);
+    if (argvars[2].v_type == VAR_UNKNOWN)
+	end = lnum;
+    else
+	end = tv_get_lnum_buf(&argvars[2], buf);
+
+    get_buffer_lines(buf, lnum, end, TRUE, rettv);
+}
+
+/*
+ * "getline(lnum, [end])" function
+ */
+    void
+f_getline(typval_T *argvars, typval_T *rettv)
+{
+    linenr_T	lnum;
+    linenr_T	end;
+    int		retlist;
+
+    lnum = tv_get_lnum(argvars);
+    if (argvars[1].v_type == VAR_UNKNOWN)
+    {
+	end = 0;
+	retlist = FALSE;
+    }
+    else
+    {
+	end = tv_get_lnum(&argvars[1]);
+	retlist = TRUE;
+    }
+
+    get_buffer_lines(curbuf, lnum, end, retlist, rettv);
+}
+
+/*
+ * "setbufline()" function
+ */
+    void
+f_setbufline(typval_T *argvars, typval_T *rettv)
+{
+    linenr_T	lnum;
+    buf_T	*buf;
+
+    buf = tv_get_buf(&argvars[0], FALSE);
+    if (buf == NULL)
+	rettv->vval.v_number = 1; // FAIL
+    else
+    {
+	lnum = tv_get_lnum_buf(&argvars[1], buf);
+	set_buffer_lines(buf, lnum, FALSE, &argvars[2], rettv);
+    }
+}
+
+/*
+ * "setline()" function
+ */
+    void
+f_setline(typval_T *argvars, typval_T *rettv)
+{
+    linenr_T	lnum = tv_get_lnum(&argvars[0]);
+
+    set_buffer_lines(curbuf, lnum, FALSE, &argvars[1], rettv);
+}
+#endif  // FEAT_EVAL
+
+#if defined(FEAT_JOB_CHANNEL) \
+	|| defined(FEAT_PYTHON) || defined(FEAT_PYTHON3) \
+	|| defined(PROTO)
+/*
+ * Make "buf" the current buffer.  restore_buffer() MUST be called to undo.
+ * No autocommands will be executed.  Use aucmd_prepbuf() if there are any.
+ */
+    void
+switch_buffer(bufref_T *save_curbuf, buf_T *buf)
+{
+    block_autocmds();
+    set_bufref(save_curbuf, curbuf);
+    --curbuf->b_nwindows;
+    curbuf = buf;
+    curwin->w_buffer = buf;
+    ++curbuf->b_nwindows;
+}
+
+/*
+ * Restore the current buffer after using switch_buffer().
+ */
+    void
+restore_buffer(bufref_T *save_curbuf)
+{
+    unblock_autocmds();
+    /* Check for valid buffer, just in case. */
+    if (bufref_valid(save_curbuf))
+    {
+	--curbuf->b_nwindows;
+	curwin->w_buffer = save_curbuf->br_buf;
+	curbuf = save_curbuf->br_buf;
+	++curbuf->b_nwindows;
+    }
+}
+
+/*
+ * Find a window for buffer "buf".
+ * If found OK is returned and "wp" and "tp" are set to the window and tabpage.
+ * If not found FAIL is returned.
+ */
+    static int
+find_win_for_buf(
+    buf_T     *buf,
+    win_T     **wp,
+    tabpage_T **tp)
+{
+    FOR_ALL_TAB_WINDOWS(*tp, *wp)
+	if ((*wp)->w_buffer == buf)
+	    return OK;
+    return FAIL;
+}
+
+/*
+ * Find a window that contains "buf" and switch to it.
+ * If there is no such window, use the current window and change "curbuf".
+ * Caller must initialize save_curbuf to NULL.
+ * restore_win_for_buf() MUST be called later!
+ */
+    void
+switch_to_win_for_buf(
+    buf_T	*buf,
+    win_T	**save_curwinp,
+    tabpage_T	**save_curtabp,
+    bufref_T	*save_curbuf)
+{
+    win_T	*wp;
+    tabpage_T	*tp;
+
+    if (find_win_for_buf(buf, &wp, &tp) == FAIL)
+	switch_buffer(save_curbuf, buf);
+    else if (switch_win(save_curwinp, save_curtabp, wp, tp, TRUE) == FAIL)
+    {
+	restore_win(*save_curwinp, *save_curtabp, TRUE);
+	switch_buffer(save_curbuf, buf);
+    }
+}
+
+    void
+restore_win_for_buf(
+    win_T	*save_curwin,
+    tabpage_T	*save_curtab,
+    bufref_T	*save_curbuf)
+{
+    if (save_curbuf->br_buf == NULL)
+	restore_win(save_curwin, save_curtab, TRUE);
+    else
+	restore_buffer(save_curbuf);
+}
+#endif