Merged from the latest developing branch.

[MacVim.git] / src / fold.c

/* vim:set ts=8 sts=4 sw=4:
 * vim600:fdm=marker fdl=1 fdc=3:
 *
 * 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.
 */

/*
 * fold.c: code for folding
 */

#include "vim.h"

#if defined(FEAT_FOLDING) || defined(PROTO)

/* local declarations. {{{1 */
/* typedef fold_T {{{2 */
/*
 * The toplevel folds for each window are stored in the w_folds growarray.
 * Each toplevel fold can contain an array of second level folds in the
 * fd_nested growarray.
 * The info stored in both growarrays is the same: An array of fold_T.
 */
typedef struct
{
    linenr_T    fd_top;         /* first line of fold; for nested fold
                                 * relative to parent */
    linenr_T    fd_len;         /* number of lines in the fold */
    garray_T    fd_nested;      /* array of nested folds */
    char        fd_flags;       /* see below */
    char        fd_small;       /* TRUE, FALSE or MAYBE: fold smaller than
                                   'foldminlines'; MAYBE applies to nested
                                   folds too */
} fold_T;

#define FD_OPEN         0       /* fold is open (nested ones can be closed) */
#define FD_CLOSED       1       /* fold is closed */
#define FD_LEVEL        2       /* depends on 'foldlevel' (nested folds too) */

#define MAX_LEVEL       20      /* maximum fold depth */

/* static functions {{{2 */
static void newFoldLevelWin __ARGS((win_T *wp));
static int checkCloseRec __ARGS((garray_T *gap, linenr_T lnum, int level));
static int foldFind __ARGS((garray_T *gap, linenr_T lnum, fold_T **fpp));
static int foldLevelWin __ARGS((win_T *wp, linenr_T lnum));
static void checkupdate __ARGS((win_T *wp));
static void setFoldRepeat __ARGS((linenr_T lnum, long count, int do_open));
static linenr_T setManualFold __ARGS((linenr_T lnum, int opening, int recurse, int *donep));
static linenr_T setManualFoldWin __ARGS((win_T *wp, linenr_T lnum, int opening, int recurse, int *donep));
static void foldOpenNested __ARGS((fold_T *fpr));
static void deleteFoldEntry __ARGS((garray_T *gap, int idx, int recursive));
static void foldMarkAdjustRecurse __ARGS((garray_T *gap, linenr_T line1, linenr_T line2, long amount, long amount_after));
static int getDeepestNestingRecurse __ARGS((garray_T *gap));
static int check_closed __ARGS((win_T *win, fold_T *fp, int *use_levelp, int level, int *maybe_smallp, linenr_T lnum_off));
static void checkSmall __ARGS((win_T *wp, fold_T *fp, linenr_T lnum_off));
static void setSmallMaybe __ARGS((garray_T *gap));
static void foldCreateMarkers __ARGS((linenr_T start, linenr_T end));
static void foldAddMarker __ARGS((linenr_T lnum, char_u *marker, int markerlen));
static void deleteFoldMarkers __ARGS((fold_T *fp, int recursive, linenr_T lnum_off));
static void foldDelMarker __ARGS((linenr_T lnum, char_u *marker, int markerlen));
static void foldUpdateIEMS __ARGS((win_T *wp, linenr_T top, linenr_T bot));
static void parseMarker __ARGS((win_T *wp));

static char *e_nofold = N_("E490: No fold found");

/*
 * While updating the folds lines between invalid_top and invalid_bot have an
 * undefined fold level.  Only used for the window currently being updated.
 */
static linenr_T invalid_top = (linenr_T)0;
static linenr_T invalid_bot = (linenr_T)0;

/*
 * When using 'foldexpr' we sometimes get the level of the next line, which
 * calls foldlevel() to get the level of the current line, which hasn't been
 * stored yet.  To get around this chicken-egg problem the level of the
 * previous line is stored here when available.  prev_lnum is zero when the
 * level is not available.
 */
static linenr_T prev_lnum = 0;
static int prev_lnum_lvl = -1;

/* Flags used for "done" argument of setManualFold. */
#define DONE_NOTHING    0
#define DONE_ACTION     1       /* did close or open a fold */
#define DONE_FOLD       2       /* did find a fold */

static int foldstartmarkerlen;
static char_u *foldendmarker;
static int foldendmarkerlen;

/* Exported folding functions. {{{1 */
/* copyFoldingState() {{{2 */
#if defined(FEAT_WINDOWS) || defined(PROTO)
/*
 * Copy that folding state from window "wp_from" to window "wp_to".
 */
    void
copyFoldingState(wp_from, wp_to)
    win_T       *wp_from;
    win_T       *wp_to;
{
    wp_to->w_fold_manual = wp_from->w_fold_manual;
    wp_to->w_foldinvalid = wp_from->w_foldinvalid;
    cloneFoldGrowArray(&wp_from->w_folds, &wp_to->w_folds);
}
#endif

/* hasAnyFolding() {{{2 */
/*
 * Return TRUE if there may be folded lines in the current window.
 */
    int
hasAnyFolding(win)
    win_T       *win;
{
    /* very simple now, but can become more complex later */
    return (win->w_p_fen
            && (!foldmethodIsManual(win) || win->w_folds.ga_len > 0));
}

/* hasFolding() {{{2 */
/*
 * Return TRUE if line "lnum" in the current window is part of a closed
 * fold.
 * When returning TRUE, *firstp and *lastp are set to the first and last
 * lnum of the sequence of folded lines (skipped when NULL).
 */
    int
hasFolding(lnum, firstp, lastp)
    linenr_T    lnum;
    linenr_T    *firstp;
    linenr_T    *lastp;
{
    return hasFoldingWin(curwin, lnum, firstp, lastp, TRUE, NULL);
}

/* hasFoldingWin() {{{2 */
    int
hasFoldingWin(win, lnum, firstp, lastp, cache, infop)
    win_T       *win;
    linenr_T    lnum;
    linenr_T    *firstp;
    linenr_T    *lastp;
    int         cache;          /* when TRUE: use cached values of window */
    foldinfo_T  *infop;         /* where to store fold info */
{
    int         had_folded = FALSE;
    linenr_T    first = 0;
    linenr_T    last = 0;
    linenr_T    lnum_rel = lnum;
    int         x;
    fold_T      *fp;
    int         level = 0;
    int         use_level = FALSE;
    int         maybe_small = FALSE;
    garray_T    *gap;
    int         low_level = 0;;

    checkupdate(win);
    /*
     * Return quickly when there is no folding at all in this window.
     */
    if (!hasAnyFolding(win))
    {
        if (infop != NULL)
            infop->fi_level = 0;
        return FALSE;
    }

    if (cache)
    {
        /*
         * First look in cached info for displayed lines.  This is probably
         * the fastest, but it can only be used if the entry is still valid.
         */
        x = find_wl_entry(win, lnum);
        if (x >= 0)
        {
            first = win->w_lines[x].wl_lnum;
            last = win->w_lines[x].wl_lastlnum;
            had_folded = win->w_lines[x].wl_folded;
        }
    }

    if (first == 0)
    {
        /*
         * Recursively search for a fold that contains "lnum".
         */
        gap = &win->w_folds;
        for (;;)
        {
            if (!foldFind(gap, lnum_rel, &fp))
                break;

            /* Remember lowest level of fold that starts in "lnum". */
            if (lnum_rel == fp->fd_top && low_level == 0)
                low_level = level + 1;

            first += fp->fd_top;
            last += fp->fd_top;

            /* is this fold closed? */
            had_folded = check_closed(win, fp, &use_level, level,
                                               &maybe_small, lnum - lnum_rel);
            if (had_folded)
            {
                /* Fold closed: Set last and quit loop. */
                last += fp->fd_len - 1;
                break;
            }

            /* Fold found, but it's open: Check nested folds.  Line number is
             * relative to containing fold. */
            gap = &fp->fd_nested;
            lnum_rel -= fp->fd_top;
            ++level;
        }
    }

    if (!had_folded)
    {
        if (infop != NULL)
        {
            infop->fi_level = level;
            infop->fi_lnum = lnum - lnum_rel;
            infop->fi_low_level = low_level == 0 ? level : low_level;
        }
        return FALSE;
    }

    if (lastp != NULL)
        *lastp = last;
    if (firstp != NULL)
        *firstp = first;
    if (infop != NULL)
    {
        infop->fi_level = level + 1;
        infop->fi_lnum = first;
        infop->fi_low_level = low_level == 0 ? level + 1 : low_level;
    }
    return TRUE;
}

/* foldLevel() {{{2 */
/*
 * Return fold level at line number "lnum" in the current window.
 */
    int
foldLevel(lnum)
    linenr_T    lnum;
{
    /* While updating the folds lines between invalid_top and invalid_bot have
     * an undefined fold level.  Otherwise update the folds first. */
    if (invalid_top == (linenr_T)0)
        checkupdate(curwin);
    else if (lnum == prev_lnum && prev_lnum_lvl >= 0)
        return prev_lnum_lvl;
    else if (lnum >= invalid_top && lnum <= invalid_bot)
        return -1;

    /* Return quickly when there is no folding at all in this window. */
    if (!hasAnyFolding(curwin))
        return 0;

    return foldLevelWin(curwin, lnum);
}

/* lineFolded() {{{2 */
/*
 * Low level function to check if a line is folded.  Doesn't use any caching.
 * Return TRUE if line is folded.
 * Return FALSE if line is not folded.
 * Return MAYBE if the line is folded when next to a folded line.
 */
    int
lineFolded(win, lnum)
    win_T       *win;
    linenr_T    lnum;
{
    return foldedCount(win, lnum, NULL) != 0;
}

/* foldedCount() {{{2 */
/*
 * Count the number of lines that are folded at line number "lnum".
 * Normally "lnum" is the first line of a possible fold, and the returned
 * number is the number of lines in the fold.
 * Doesn't use caching from the displayed window.
 * Returns number of folded lines from "lnum", or 0 if line is not folded.
 * When "infop" is not NULL, fills *infop with the fold level info.
 */
    long
foldedCount(win, lnum, infop)
    win_T       *win;
    linenr_T    lnum;
    foldinfo_T  *infop;
{
    linenr_T    last;

    if (hasFoldingWin(win, lnum, NULL, &last, FALSE, infop))
        return (long)(last - lnum + 1);
    return 0;
}

/* foldmethodIsManual() {{{2 */
/*
 * Return TRUE if 'foldmethod' is "manual"
 */
    int
foldmethodIsManual(wp)
    win_T       *wp;
{
    return (wp->w_p_fdm[3] == 'u');
}

/* foldmethodIsIndent() {{{2 */
/*
 * Return TRUE if 'foldmethod' is "indent"
 */
    int
foldmethodIsIndent(wp)
    win_T       *wp;
{
    return (wp->w_p_fdm[0] == 'i');
}

/* foldmethodIsExpr() {{{2 */
/*
 * Return TRUE if 'foldmethod' is "expr"
 */
    int
foldmethodIsExpr(wp)
    win_T       *wp;
{
    return (wp->w_p_fdm[1] == 'x');
}

/* foldmethodIsMarker() {{{2 */
/*
 * Return TRUE if 'foldmethod' is "marker"
 */
    int
foldmethodIsMarker(wp)
    win_T       *wp;
{
    return (wp->w_p_fdm[2] == 'r');
}

/* foldmethodIsSyntax() {{{2 */
/*
 * Return TRUE if 'foldmethod' is "syntax"
 */
    int
foldmethodIsSyntax(wp)
    win_T       *wp;
{
    return (wp->w_p_fdm[0] == 's');
}

/* foldmethodIsDiff() {{{2 */
/*
 * Return TRUE if 'foldmethod' is "diff"
 */
    int
foldmethodIsDiff(wp)
    win_T       *wp;
{
    return (wp->w_p_fdm[0] == 'd');
}

/* closeFold() {{{2 */
/*
 * Close fold for current window at line "lnum".
 * Repeat "count" times.
 */
    void
closeFold(lnum, count)
    linenr_T    lnum;
    long        count;
{
    setFoldRepeat(lnum, count, FALSE);
}

/* closeFoldRecurse() {{{2 */
/*
 * Close fold for current window at line "lnum" recursively.
 */
    void
closeFoldRecurse(lnum)
    linenr_T    lnum;
{
    (void)setManualFold(lnum, FALSE, TRUE, NULL);
}

/* opFoldRange() {{{2 */
/*
 * Open or Close folds for current window in lines "first" to "last".
 * Used for "zo", "zO", "zc" and "zC" in Visual mode.
 */
    void
opFoldRange(first, last, opening, recurse, had_visual)
    linenr_T    first;
    linenr_T    last;
    int         opening;        /* TRUE to open, FALSE to close */
    int         recurse;        /* TRUE to do it recursively */
    int         had_visual;     /* TRUE when Visual selection used */
{
    int         done = DONE_NOTHING;    /* avoid error messages */
    linenr_T    lnum;
    linenr_T    lnum_next;

    for (lnum = first; lnum <= last; lnum = lnum_next + 1)
    {
        lnum_next = lnum;
        /* Opening one level only: next fold to open is after the one going to
         * be opened. */
        if (opening && !recurse)
            (void)hasFolding(lnum, NULL, &lnum_next);
        (void)setManualFold(lnum, opening, recurse, &done);
        /* Closing one level only: next line to close a fold is after just
         * closed fold. */
        if (!opening && !recurse)
            (void)hasFolding(lnum, NULL, &lnum_next);
    }
    if (done == DONE_NOTHING)
        EMSG(_(e_nofold));
#ifdef FEAT_VISUAL
    /* Force a redraw to remove the Visual highlighting. */
    if (had_visual)
        redraw_curbuf_later(INVERTED);
#endif
}

/* openFold() {{{2 */
/*
 * Open fold for current window at line "lnum".
 * Repeat "count" times.
 */
    void
openFold(lnum, count)
    linenr_T    lnum;
    long        count;
{
    setFoldRepeat(lnum, count, TRUE);
}

/* openFoldRecurse() {{{2 */
/*
 * Open fold for current window at line "lnum" recursively.
 */
    void
openFoldRecurse(lnum)
    linenr_T    lnum;
{
    (void)setManualFold(lnum, TRUE, TRUE, NULL);
}

/* foldOpenCursor() {{{2 */
/*
 * Open folds until the cursor line is not in a closed fold.
 */
    void
foldOpenCursor()
{
    int         done;

    checkupdate(curwin);
    if (hasAnyFolding(curwin))
        for (;;)
        {
            done = DONE_NOTHING;
            (void)setManualFold(curwin->w_cursor.lnum, TRUE, FALSE, &done);
            if (!(done & DONE_ACTION))
                break;
        }
}

/* newFoldLevel() {{{2 */
/*
 * Set new foldlevel for current window.
 */
    void
newFoldLevel()
{
    newFoldLevelWin(curwin);

#ifdef FEAT_DIFF
    if (foldmethodIsDiff(curwin) && curwin->w_p_scb)
    {
        win_T       *wp;

        /*
         * Set the same foldlevel in other windows in diff mode.
         */
        FOR_ALL_WINDOWS(wp)
        {
            if (wp != curwin && foldmethodIsDiff(wp) && wp->w_p_scb)
            {
                wp->w_p_fdl = curwin->w_p_fdl;
                newFoldLevelWin(wp);
            }
        }
    }
#endif
}

    static void
newFoldLevelWin(wp)
    win_T       *wp;
{
    fold_T      *fp;
    int         i;

    checkupdate(wp);
    if (wp->w_fold_manual)
    {
        /* Set all flags for the first level of folds to FD_LEVEL.  Following
         * manual open/close will then change the flags to FD_OPEN or
         * FD_CLOSED for those folds that don't use 'foldlevel'. */
        fp = (fold_T *)wp->w_folds.ga_data;
        for (i = 0; i < wp->w_folds.ga_len; ++i)
            fp[i].fd_flags = FD_LEVEL;
        wp->w_fold_manual = FALSE;
    }
    changed_window_setting_win(wp);
}

/* foldCheckClose() {{{2 */
/*
 * Apply 'foldlevel' to all folds that don't contain the cursor.
 */
    void
foldCheckClose()
{
    if (*p_fcl != NUL)  /* can only be "all" right now */
    {
        checkupdate(curwin);
        if (checkCloseRec(&curwin->w_folds, curwin->w_cursor.lnum,
                                                        (int)curwin->w_p_fdl))
            changed_window_setting();
    }
}

/* checkCloseRec() {{{2 */
    static int
checkCloseRec(gap, lnum, level)
    garray_T    *gap;
    linenr_T    lnum;
    int         level;
{
    fold_T      *fp;
    int         retval = FALSE;
    int         i;

    fp = (fold_T *)gap->ga_data;
    for (i = 0; i < gap->ga_len; ++i)
    {
        /* Only manually opened folds may need to be closed. */
        if (fp[i].fd_flags == FD_OPEN)
        {
            if (level <= 0 && (lnum < fp[i].fd_top
                                      || lnum >= fp[i].fd_top + fp[i].fd_len))
            {
                fp[i].fd_flags = FD_LEVEL;
                retval = TRUE;
            }
            else
                retval |= checkCloseRec(&fp[i].fd_nested, lnum - fp[i].fd_top,
                                                                   level - 1);
        }
    }
    return retval;
}

/* foldCreateAllowed() {{{2 */
/*
 * Return TRUE if it's allowed to manually create or delete a fold.
 * Give an error message and return FALSE if not.
 */
    int
foldManualAllowed(create)
    int         create;
{
    if (foldmethodIsManual(curwin) || foldmethodIsMarker(curwin))
        return TRUE;
    if (create)
        EMSG(_("E350: Cannot create fold with current 'foldmethod'"));
    else
        EMSG(_("E351: Cannot delete fold with current 'foldmethod'"));
    return FALSE;
}

/* foldCreate() {{{2 */
/*
 * Create a fold from line "start" to line "end" (inclusive) in the current
 * window.
 */
    void
foldCreate(start, end)
    linenr_T    start;
    linenr_T    end;
{
    fold_T      *fp;
    garray_T    *gap;
    garray_T    fold_ga;
    int         i, j;
    int         cont;
    int         use_level = FALSE;
    int         closed = FALSE;
    int         level = 0;
    linenr_T    start_rel = start;
    linenr_T    end_rel = end;

    if (start > end)
    {
        /* reverse the range */
        end = start_rel;
        start = end_rel;
        start_rel = start;
        end_rel = end;
    }

    /* When 'foldmethod' is "marker" add markers, which creates the folds. */
    if (foldmethodIsMarker(curwin))
    {
        foldCreateMarkers(start, end);
        return;
    }

    checkupdate(curwin);

    /* Find the place to insert the new fold. */
    gap = &curwin->w_folds;
    for (;;)
    {
        if (!foldFind(gap, start_rel, &fp))
            break;
        if (fp->fd_top + fp->fd_len > end_rel)
        {
            /* New fold is completely inside this fold: Go one level deeper. */
            gap = &fp->fd_nested;
            start_rel -= fp->fd_top;
            end_rel -= fp->fd_top;
            if (use_level || fp->fd_flags == FD_LEVEL)
            {
                use_level = TRUE;
                if (level >= curwin->w_p_fdl)
                    closed = TRUE;
            }
            else if (fp->fd_flags == FD_CLOSED)
                closed = TRUE;
            ++level;
        }
        else
        {
            /* This fold and new fold overlap: Insert here and move some folds
             * inside the new fold. */
            break;
        }
    }

    i = (int)(fp - (fold_T *)gap->ga_data);
    if (ga_grow(gap, 1) == OK)
    {
        fp = (fold_T *)gap->ga_data + i;
        ga_init2(&fold_ga, (int)sizeof(fold_T), 10);

        /* Count number of folds that will be contained in the new fold. */
        for (cont = 0; i + cont < gap->ga_len; ++cont)
            if (fp[cont].fd_top > end_rel)
                break;
        if (cont > 0 && ga_grow(&fold_ga, cont) == OK)
        {
            /* If the first fold starts before the new fold, let the new fold
             * start there.  Otherwise the existing fold would change. */
            if (start_rel > fp->fd_top)
                start_rel = fp->fd_top;

            /* When last contained fold isn't completely contained, adjust end
             * of new fold. */
            if (end_rel < fp[cont - 1].fd_top + fp[cont - 1].fd_len - 1)
                end_rel = fp[cont - 1].fd_top + fp[cont - 1].fd_len - 1;
            /* Move contained folds to inside new fold. */
            mch_memmove(fold_ga.ga_data, fp, sizeof(fold_T) * cont);
            fold_ga.ga_len += cont;
            i += cont;

            /* Adjust line numbers in contained folds to be relative to the
             * new fold. */
            for (j = 0; j < cont; ++j)
                ((fold_T *)fold_ga.ga_data)[j].fd_top -= start_rel;
        }
        /* Move remaining entries to after the new fold. */
        if (i < gap->ga_len)
            mch_memmove(fp + 1, (fold_T *)gap->ga_data + i,
                                     sizeof(fold_T) * (gap->ga_len - i));
        gap->ga_len = gap->ga_len + 1 - cont;

        /* insert new fold */
        fp->fd_nested = fold_ga;
        fp->fd_top = start_rel;
        fp->fd_len = end_rel - start_rel + 1;

        /* We want the new fold to be closed.  If it would remain open because
         * of using 'foldlevel', need to adjust fd_flags of containing folds.
         */
        if (use_level && !closed && level < curwin->w_p_fdl)
            closeFold(start, 1L);
        if (!use_level)
            curwin->w_fold_manual = TRUE;
        fp->fd_flags = FD_CLOSED;
        fp->fd_small = MAYBE;

        /* redraw */
        changed_window_setting();
    }
}

/* deleteFold() {{{2 */
/*
 * Delete a fold at line "start" in the current window.
 * When "end" is not 0, delete all folds from "start" to "end".
 * When "recursive" is TRUE delete recursively.
 */
    void
deleteFold(start, end, recursive, had_visual)
    linenr_T    start;
    linenr_T    end;
    int         recursive;
    int         had_visual;     /* TRUE when Visual selection used */
{
    garray_T    *gap;
    fold_T      *fp;
    garray_T    *found_ga;
    fold_T      *found_fp = NULL;
    linenr_T    found_off = 0;
    int         use_level;
    int         maybe_small = FALSE;
    int         level = 0;
    linenr_T    lnum = start;
    linenr_T    lnum_off;
    int         did_one = FALSE;
    linenr_T    first_lnum = MAXLNUM;
    linenr_T    last_lnum = 0;

    checkupdate(curwin);

    while (lnum <= end)
    {
        /* Find the deepest fold for "start". */
        gap = &curwin->w_folds;
        found_ga = NULL;
        lnum_off = 0;
        use_level = FALSE;
        for (;;)
        {
            if (!foldFind(gap, lnum - lnum_off, &fp))
                break;
            /* lnum is inside this fold, remember info */
            found_ga = gap;
            found_fp = fp;
            found_off = lnum_off;

            /* if "lnum" is folded, don't check nesting */
            if (check_closed(curwin, fp, &use_level, level,
                                                      &maybe_small, lnum_off))
                break;

            /* check nested folds */
            gap = &fp->fd_nested;
            lnum_off += fp->fd_top;
            ++level;
        }
        if (found_ga == NULL)
        {
            ++lnum;
        }
        else
        {
            lnum = found_fp->fd_top + found_fp->fd_len + found_off;

            if (foldmethodIsManual(curwin))
                deleteFoldEntry(found_ga,
                    (int)(found_fp - (fold_T *)found_ga->ga_data), recursive);
            else
            {
                if (first_lnum > found_fp->fd_top + found_off)
                    first_lnum = found_fp->fd_top + found_off;
                if (last_lnum < lnum)
                    last_lnum = lnum;
                if (!did_one)
                    parseMarker(curwin);
                deleteFoldMarkers(found_fp, recursive, found_off);
            }
            did_one = TRUE;

            /* redraw window */
            changed_window_setting();
        }
    }
    if (!did_one)
    {
        EMSG(_(e_nofold));
#ifdef FEAT_VISUAL
        /* Force a redraw to remove the Visual highlighting. */
        if (had_visual)
            redraw_curbuf_later(INVERTED);
#endif
    }
    else
        /* Deleting markers may make cursor column invalid. */
        check_cursor_col();

    if (last_lnum > 0)
        changed_lines(first_lnum, (colnr_T)0, last_lnum, 0L);
}

/* clearFolding() {{{2 */
/*
 * Remove all folding for window "win".
 */
    void
clearFolding(win)
    win_T       *win;
{
    deleteFoldRecurse(&win->w_folds);
    win->w_foldinvalid = FALSE;
}

/* foldUpdate() {{{2 */
/*
 * Update folds for changes in the buffer of a window.
 * Note that inserted/deleted lines must have already been taken care of by
 * calling foldMarkAdjust().
 * The changes in lines from top to bot (inclusive).
 */
    void
foldUpdate(wp, top, bot)
    win_T       *wp;
    linenr_T    top;
    linenr_T    bot;
{
    fold_T      *fp;

    /* Mark all folds from top to bot as maybe-small. */
    (void)foldFind(&curwin->w_folds, top, &fp);
    while (fp < (fold_T *)curwin->w_folds.ga_data + curwin->w_folds.ga_len
            && fp->fd_top < bot)
    {
        fp->fd_small = MAYBE;

        /* Not sure if this is the right place to reset fd_flags (suggested by
         * Lech Lorens). */
        if (wp->w_foldinvalid)
            fp->fd_flags = FD_LEVEL;

        ++fp;
    }

    if (foldmethodIsIndent(wp)
            || foldmethodIsExpr(wp)
            || foldmethodIsMarker(wp)
#ifdef FEAT_DIFF
            || foldmethodIsDiff(wp)
#endif
            || foldmethodIsSyntax(wp))
    {
        int save_got_int = got_int;

        /* reset got_int here, otherwise it won't work */
        got_int = FALSE;
        foldUpdateIEMS(wp, top, bot);
        got_int |= save_got_int;
    }
}

/* foldUpdateAll() {{{2 */
/*
 * Update all lines in a window for folding.
 * Used when a fold setting changes or after reloading the buffer.
 * The actual updating is postponed until fold info is used, to avoid doing
 * every time a setting is changed or a syntax item is added.
 */
    void
foldUpdateAll(win)
    win_T       *win;
{
    win->w_foldinvalid = TRUE;
    redraw_win_later(win, NOT_VALID);
}

/* foldMoveTo() {{{2 */
/*
 * If "updown" is FALSE: Move to the start or end of the fold.
 * If "updown" is TRUE: move to fold at the same level.
 * If not moved return FAIL.
 */
    int
foldMoveTo(updown, dir, count)
    int         updown;
    int         dir;        /* FORWARD or BACKWARD */
    long        count;
{
    long        n;
    int         retval = FAIL;
    linenr_T    lnum_off;
    linenr_T    lnum_found;
    linenr_T    lnum;
    int         use_level;
    int         maybe_small;
    garray_T    *gap;
    fold_T      *fp;
    int         level;
    int         last;

    checkupdate(curwin);

    /* Repeat "count" times. */
    for (n = 0; n < count; ++n)
    {
        /* Find nested folds.  Stop when a fold is closed.  The deepest fold
         * that moves the cursor is used. */
        lnum_off = 0;
        gap = &curwin->w_folds;
        use_level = FALSE;
        maybe_small = FALSE;
        lnum_found = curwin->w_cursor.lnum;
        level = 0;
        last = FALSE;
        for (;;)
        {
            if (!foldFind(gap, curwin->w_cursor.lnum - lnum_off, &fp))
            {
                if (!updown)
                    break;

                /* When moving up, consider a fold above the cursor; when
                 * moving down consider a fold below the cursor. */
                if (dir == FORWARD)
                {
                    if (fp - (fold_T *)gap->ga_data >= gap->ga_len)
                        break;
                    --fp;
                }
                else
                {
                    if (fp == (fold_T *)gap->ga_data)
                        break;
                }
                /* don't look for contained folds, they will always move
                 * the cursor too far. */
                last = TRUE;
            }

            if (!last)
            {
                /* Check if this fold is closed. */
                if (check_closed(curwin, fp, &use_level, level,
                                                      &maybe_small, lnum_off))
                    last = TRUE;

                /* "[z" and "]z" stop at closed fold */
                if (last && !updown)
                    break;
            }

            if (updown)
            {
                if (dir == FORWARD)
                {
                    /* to start of next fold if there is one */
                    if (fp + 1 - (fold_T *)gap->ga_data < gap->ga_len)
                    {
                        lnum = fp[1].fd_top + lnum_off;
                        if (lnum > curwin->w_cursor.lnum)
                            lnum_found = lnum;
                    }
                }
                else
                {
                    /* to end of previous fold if there is one */
                    if (fp > (fold_T *)gap->ga_data)
                    {
                        lnum = fp[-1].fd_top + lnum_off + fp[-1].fd_len - 1;
                        if (lnum < curwin->w_cursor.lnum)
                            lnum_found = lnum;
                    }
                }
            }
            else
            {
                /* Open fold found, set cursor to its start/end and then check
                 * nested folds. */
                if (dir == FORWARD)
                {
                    lnum = fp->fd_top + lnum_off + fp->fd_len - 1;
                    if (lnum > curwin->w_cursor.lnum)
                        lnum_found = lnum;
                }
                else
                {
                    lnum = fp->fd_top + lnum_off;
                    if (lnum < curwin->w_cursor.lnum)
                        lnum_found = lnum;
                }
            }

            if (last)
                break;

            /* Check nested folds (if any). */
            gap = &fp->fd_nested;
            lnum_off += fp->fd_top;
            ++level;
        }
        if (lnum_found != curwin->w_cursor.lnum)
        {
            if (retval == FAIL)
                setpcmark();
            curwin->w_cursor.lnum = lnum_found;
            curwin->w_cursor.col = 0;
            retval = OK;
        }
        else
            break;
    }

    return retval;
}

/* foldInitWin() {{{2 */
/*
 * Init the fold info in a new window.
 */
    void
foldInitWin(newwin)
    win_T       *newwin;
{
    ga_init2(&newwin->w_folds, (int)sizeof(fold_T), 10);
}

/* find_wl_entry() {{{2 */
/*
 * Find an entry in the win->w_lines[] array for buffer line "lnum".
 * Only valid entries are considered (for entries where wl_valid is FALSE the
 * line number can be wrong).
 * Returns index of entry or -1 if not found.
 */
    int
find_wl_entry(win, lnum)
    win_T       *win;
    linenr_T    lnum;
{
    int         i;

    if (win->w_lines_valid > 0)
        for (i = 0; i < win->w_lines_valid; ++i)
            if (win->w_lines[i].wl_valid)
            {
                if (lnum < win->w_lines[i].wl_lnum)
                    return -1;
                if (lnum <= win->w_lines[i].wl_lastlnum)
                    return i;
            }
    return -1;
}

/* foldAdjustVisual() {{{2 */
#ifdef FEAT_VISUAL
/*
 * Adjust the Visual area to include any fold at the start or end completely.
 */
    void
foldAdjustVisual()
{
    pos_T       *start, *end;
    char_u      *ptr;

    if (!VIsual_active || !hasAnyFolding(curwin))
        return;

    if (ltoreq(VIsual, curwin->w_cursor))
    {
        start = &VIsual;
        end = &curwin->w_cursor;
    }
    else
    {
        start = &curwin->w_cursor;
        end = &VIsual;
    }
    if (hasFolding(start->lnum, &start->lnum, NULL))
        start->col = 0;
    if (hasFolding(end->lnum, NULL, &end->lnum))
    {
        ptr = ml_get(end->lnum);
        end->col = (colnr_T)STRLEN(ptr);
        if (end->col > 0 && *p_sel == 'o')
            --end->col;
#ifdef FEAT_MBYTE
        /* prevent cursor from moving on the trail byte */
        if (has_mbyte)
            mb_adjust_cursor();
#endif
    }
}
#endif

/* cursor_foldstart() {{{2 */
/*
 * Move the cursor to the first line of a closed fold.
 */
    void
foldAdjustCursor()
{
    (void)hasFolding(curwin->w_cursor.lnum, &curwin->w_cursor.lnum, NULL);
}

/* Internal functions for "fold_T" {{{1 */
/* cloneFoldGrowArray() {{{2 */
/*
 * Will "clone" (i.e deep copy) a garray_T of folds.
 *
 * Return FAIL if the operation cannot be completed, otherwise OK.
 */
    void
cloneFoldGrowArray(from, to)
    garray_T    *from;
    garray_T    *to;
{
    int         i;
    fold_T      *from_p;
    fold_T      *to_p;

    ga_init2(to, from->ga_itemsize, from->ga_growsize);
    if (from->ga_len == 0 || ga_grow(to, from->ga_len) == FAIL)
        return;

    from_p = (fold_T *)from->ga_data;
    to_p = (fold_T *)to->ga_data;

    for (i = 0; i < from->ga_len; i++)
    {
        to_p->fd_top = from_p->fd_top;
        to_p->fd_len = from_p->fd_len;
        to_p->fd_flags = from_p->fd_flags;
        to_p->fd_small = from_p->fd_small;
        cloneFoldGrowArray(&from_p->fd_nested, &to_p->fd_nested);
        ++to->ga_len;
        ++from_p;
        ++to_p;
    }
}

/* foldFind() {{{2 */
/*
 * Search for line "lnum" in folds of growarray "gap".
 * Set *fpp to the fold struct for the fold that contains "lnum" or
 * the first fold below it (careful: it can be beyond the end of the array!).
 * Returns FALSE when there is no fold that contains "lnum".
 */
    static int
foldFind(gap, lnum, fpp)
    garray_T    *gap;
    linenr_T    lnum;
    fold_T      **fpp;
{
    linenr_T    low, high;
    fold_T      *fp;
    int         i;

    /*
     * Perform a binary search.
     * "low" is lowest index of possible match.
     * "high" is highest index of possible match.
     */
    fp = (fold_T *)gap->ga_data;
    low = 0;
    high = gap->ga_len - 1;
    while (low <= high)
    {
        i = (low + high) / 2;
        if (fp[i].fd_top > lnum)
            /* fold below lnum, adjust high */
            high = i - 1;
        else if (fp[i].fd_top + fp[i].fd_len <= lnum)
            /* fold above lnum, adjust low */
            low = i + 1;
        else
        {
            /* lnum is inside this fold */
            *fpp = fp + i;
            return TRUE;
        }
    }
    *fpp = fp + low;
    return FALSE;
}

/* foldLevelWin() {{{2 */
/*
 * Return fold level at line number "lnum" in window "wp".
 */
    static int
foldLevelWin(wp, lnum)
    win_T       *wp;
    linenr_T    lnum;
{
    fold_T      *fp;
    linenr_T    lnum_rel = lnum;
    int         level =  0;
    garray_T    *gap;

    /* Recursively search for a fold that contains "lnum". */
    gap = &wp->w_folds;
    for (;;)
    {
        if (!foldFind(gap, lnum_rel, &fp))
            break;
        /* Check nested folds.  Line number is relative to containing fold. */
        gap = &fp->fd_nested;
        lnum_rel -= fp->fd_top;
        ++level;
    }

    return level;
}

/* checkupdate() {{{2 */
/*
 * Check if the folds in window "wp" are invalid and update them if needed.
 */
    static void
checkupdate(wp)
    win_T       *wp;
{
    if (wp->w_foldinvalid)
    {
        foldUpdate(wp, (linenr_T)1, (linenr_T)MAXLNUM); /* will update all */
        wp->w_foldinvalid = FALSE;
    }
}

/* setFoldRepeat() {{{2 */
/*
 * Open or close fold for current window at line "lnum".
 * Repeat "count" times.
 */
    static void
setFoldRepeat(lnum, count, do_open)
    linenr_T    lnum;
    long        count;
    int         do_open;
{
    int         done;
    long        n;

    for (n = 0; n < count; ++n)
    {
        done = DONE_NOTHING;
        (void)setManualFold(lnum, do_open, FALSE, &done);
        if (!(done & DONE_ACTION))
        {
            /* Only give an error message when no fold could be opened. */
            if (n == 0 && !(done & DONE_FOLD))
                EMSG(_(e_nofold));
            break;
        }
    }
}

/* setManualFold() {{{2 */
/*
 * Open or close the fold in the current window which contains "lnum".
 * Also does this for other windows in diff mode when needed.
 */
    static linenr_T
setManualFold(lnum, opening, recurse, donep)
    linenr_T    lnum;
    int         opening;    /* TRUE when opening, FALSE when closing */
    int         recurse;    /* TRUE when closing/opening recursive */
    int         *donep;
{
#ifdef FEAT_DIFF
    if (foldmethodIsDiff(curwin) && curwin->w_p_scb)
    {
        win_T       *wp;
        linenr_T    dlnum;

        /*
         * Do the same operation in other windows in diff mode.  Calculate the
         * line number from the diffs.
         */
        FOR_ALL_WINDOWS(wp)
        {
            if (wp != curwin && foldmethodIsDiff(wp) && wp->w_p_scb)
            {
                dlnum = diff_lnum_win(curwin->w_cursor.lnum, wp);
                if (dlnum != 0)
                    (void)setManualFoldWin(wp, dlnum, opening, recurse, NULL);
            }
        }
    }
#endif

    return setManualFoldWin(curwin, lnum, opening, recurse, donep);
}

/* setManualFoldWin() {{{2 */
/*
 * Open or close the fold in window "wp" which contains "lnum".
 * "donep", when not NULL, points to flag that is set to DONE_FOLD when some
 * fold was found and to DONE_ACTION when some fold was opened or closed.
 * When "donep" is NULL give an error message when no fold was found for
 * "lnum", but only if "wp" is "curwin".
 * Return the line number of the next line that could be closed.
 * It's only valid when "opening" is TRUE!
 */
    static linenr_T
setManualFoldWin(wp, lnum, opening, recurse, donep)
    win_T       *wp;
    linenr_T    lnum;
    int         opening;    /* TRUE when opening, FALSE when closing */
    int         recurse;    /* TRUE when closing/opening recursive */
    int         *donep;
{
    fold_T      *fp;
    fold_T      *fp2;
    fold_T      *found = NULL;
    int         j;
    int         level = 0;
    int         use_level = FALSE;
    int         found_fold = FALSE;
    garray_T    *gap;
    linenr_T    next = MAXLNUM;
    linenr_T    off = 0;
    int         done = 0;

    checkupdate(wp);

    /*
     * Find the fold, open or close it.
     */
    gap = &wp->w_folds;
    for (;;)
    {
        if (!foldFind(gap, lnum, &fp))
        {
            /* If there is a following fold, continue there next time. */
            if (fp < (fold_T *)gap->ga_data + gap->ga_len)
                next = fp->fd_top + off;
            break;
        }

        /* lnum is inside this fold */
        found_fold = TRUE;

        /* If there is a following fold, continue there next time. */
        if (fp + 1 < (fold_T *)gap->ga_data + gap->ga_len)
            next = fp[1].fd_top + off;

        /* Change from level-dependent folding to manual. */
        if (use_level || fp->fd_flags == FD_LEVEL)
        {
            use_level = TRUE;
            if (level >= wp->w_p_fdl)
                fp->fd_flags = FD_CLOSED;
            else
                fp->fd_flags = FD_OPEN;
            fp2 = (fold_T *)fp->fd_nested.ga_data;
            for (j = 0; j < fp->fd_nested.ga_len; ++j)
                fp2[j].fd_flags = FD_LEVEL;
        }

        /* Simple case: Close recursively means closing the fold. */
        if (!opening && recurse)
        {
            if (fp->fd_flags != FD_CLOSED)
            {
                done |= DONE_ACTION;
                fp->fd_flags = FD_CLOSED;
            }
        }
        else if (fp->fd_flags == FD_CLOSED)
        {
            /* When opening, open topmost closed fold. */
            if (opening)
            {
                fp->fd_flags = FD_OPEN;
                done |= DONE_ACTION;
                if (recurse)
                    foldOpenNested(fp);
            }
            break;
        }

        /* fold is open, check nested folds */
        found = fp;
        gap = &fp->fd_nested;
        lnum -= fp->fd_top;
        off += fp->fd_top;
        ++level;
    }
    if (found_fold)
    {
        /* When closing and not recurse, close deepest open fold. */
        if (!opening && found != NULL)
        {
            found->fd_flags = FD_CLOSED;
            done |= DONE_ACTION;
        }
        wp->w_fold_manual = TRUE;
        if (done & DONE_ACTION)
            changed_window_setting_win(wp);
        done |= DONE_FOLD;
    }
    else if (donep == NULL && wp == curwin)
        EMSG(_(e_nofold));

    if (donep != NULL)
        *donep |= done;

    return next;
}

/* foldOpenNested() {{{2 */
/*
 * Open all nested folds in fold "fpr" recursively.
 */
    static void
foldOpenNested(fpr)
    fold_T      *fpr;
{
    int         i;
    fold_T      *fp;

    fp = (fold_T *)fpr->fd_nested.ga_data;
    for (i = 0; i < fpr->fd_nested.ga_len; ++i)
    {
        foldOpenNested(&fp[i]);
        fp[i].fd_flags = FD_OPEN;
    }
}

/* deleteFoldEntry() {{{2 */
/*
 * Delete fold "idx" from growarray "gap".
 * When "recursive" is TRUE also delete all the folds contained in it.
 * When "recursive" is FALSE contained folds are moved one level up.
 */
    static void
deleteFoldEntry(gap, idx, recursive)
    garray_T    *gap;
    int         idx;
    int         recursive;
{
    fold_T      *fp;
    int         i;
    long        moved;
    fold_T      *nfp;

    fp = (fold_T *)gap->ga_data + idx;
    if (recursive || fp->fd_nested.ga_len == 0)
    {
        /* recursively delete the contained folds */
        deleteFoldRecurse(&fp->fd_nested);
        --gap->ga_len;
        if (idx < gap->ga_len)
            mch_memmove(fp, fp + 1, sizeof(fold_T) * (gap->ga_len - idx));
    }
    else
    {
        /* move nested folds one level up, to overwrite the fold that is
         * deleted. */
        moved = fp->fd_nested.ga_len;
        if (ga_grow(gap, (int)(moved - 1)) == OK)
        {
            /* adjust fd_top and fd_flags for the moved folds */
            nfp = (fold_T *)fp->fd_nested.ga_data;
            for (i = 0; i < moved; ++i)
            {
                nfp[i].fd_top += fp->fd_top;
                if (fp->fd_flags == FD_LEVEL)
                    nfp[i].fd_flags = FD_LEVEL;
                if (fp->fd_small == MAYBE)
                    nfp[i].fd_small = MAYBE;
            }

            /* move the existing folds down to make room */
            if (idx < gap->ga_len)
                mch_memmove(fp + moved, fp + 1,
                                        sizeof(fold_T) * (gap->ga_len - idx));
            /* move the contained folds one level up */
            mch_memmove(fp, nfp, (size_t)(sizeof(fold_T) * moved));
            vim_free(nfp);
            gap->ga_len += moved - 1;
        }
    }
}

/* deleteFoldRecurse() {{{2 */
/*
 * Delete nested folds in a fold.
 */
    void
deleteFoldRecurse(gap)
    garray_T    *gap;
{
    int         i;

    for (i = 0; i < gap->ga_len; ++i)
        deleteFoldRecurse(&(((fold_T *)(gap->ga_data))[i].fd_nested));
    ga_clear(gap);
}

/* foldMarkAdjust() {{{2 */
/*
 * Update line numbers of folds for inserted/deleted lines.
 */
    void
foldMarkAdjust(wp, line1, line2, amount, amount_after)
    win_T       *wp;
    linenr_T    line1;
    linenr_T    line2;
    long        amount;
    long        amount_after;
{
    /* If deleting marks from line1 to line2, but not deleting all those
     * lines, set line2 so that only deleted lines have their folds removed. */
    if (amount == MAXLNUM && line2 >= line1 && line2 - line1 >= -amount_after)
        line2 = line1 - amount_after - 1;
    /* If appending a line in Insert mode, it should be included in the fold
     * just above the line. */
    if ((State & INSERT) && amount == (linenr_T)1 && line2 == MAXLNUM)
        --line1;
    foldMarkAdjustRecurse(&wp->w_folds, line1, line2, amount, amount_after);
}

/* foldMarkAdjustRecurse() {{{2 */
    static void
foldMarkAdjustRecurse(gap, line1, line2, amount, amount_after)
    garray_T    *gap;
    linenr_T    line1;
    linenr_T    line2;
    long        amount;
    long        amount_after;
{
    fold_T      *fp;
    int         i;
    linenr_T    last;
    linenr_T    top;

    /* In Insert mode an inserted line at the top of a fold is considered part
     * of the fold, otherwise it isn't. */
    if ((State & INSERT) && amount == (linenr_T)1 && line2 == MAXLNUM)
        top = line1 + 1;
    else
        top = line1;

    /* Find the fold containing or just below "line1". */
    (void)foldFind(gap, line1, &fp);

    /*
     * Adjust all folds below "line1" that are affected.
     */
    for (i = (int)(fp - (fold_T *)gap->ga_data); i < gap->ga_len; ++i, ++fp)
    {
        /*
         * Check for these situations:
         *        1  2  3
         *        1  2  3
         * line1     2  3  4  5
         *           2  3  4  5
         *           2  3  4  5
         * line2     2  3  4  5
         *              3     5  6
         *              3     5  6
         */

        last = fp->fd_top + fp->fd_len - 1; /* last line of fold */

        /* 1. fold completely above line1: nothing to do */
        if (last < line1)
            continue;

        /* 6. fold below line2: only adjust for amount_after */
        if (fp->fd_top > line2)
        {
            if (amount_after == 0)
                break;
            fp->fd_top += amount_after;
        }
        else
        {
            if (fp->fd_top >= top && last <= line2)
            {
                /* 4. fold completely contained in range */
                if (amount == MAXLNUM)
                {
                    /* Deleting lines: delete the fold completely */
                    deleteFoldEntry(gap, i, TRUE);
                    --i;    /* adjust index for deletion */
                    --fp;
                }
                else
                    fp->fd_top += amount;
            }
            else
            {
                if (fp->fd_top < top)
                {
                    /* 2 or 3: need to correct nested folds too */
                    foldMarkAdjustRecurse(&fp->fd_nested, line1 - fp->fd_top,
                                  line2 - fp->fd_top, amount, amount_after);
                    if (last <= line2)
                    {
                        /* 2. fold contains line1, line2 is below fold */
                        if (amount == MAXLNUM)
                            fp->fd_len = line1 - fp->fd_top;
                        else
                            fp->fd_len += amount;
                    }
                    else
                    {
                        /* 3. fold contains line1 and line2 */
                        fp->fd_len += amount_after;
                    }
                }
                else
                {
                    /* 5. fold is below line1 and contains line2; need to
                     * correct nested folds too */
                    foldMarkAdjustRecurse(&fp->fd_nested, line1 - fp->fd_top,
                                  line2 - fp->fd_top, amount,
                                  amount_after + (fp->fd_top - top));
                    if (amount == MAXLNUM)
                    {
                        fp->fd_len -= line2 - fp->fd_top + 1;
                        fp->fd_top = line1;
                    }
                    else
                    {
                        fp->fd_len += amount_after - amount;
                        fp->fd_top += amount;
                    }
                }
            }
        }
    }
}

/* getDeepestNesting() {{{2 */
/*
 * Get the lowest 'foldlevel' value that makes the deepest nested fold in the
 * current window open.
 */
    int
getDeepestNesting()
{
    checkupdate(curwin);
    return getDeepestNestingRecurse(&curwin->w_folds);
}

    static int
getDeepestNestingRecurse(gap)
    garray_T    *gap;
{
    int         i;
    int         level;
    int         maxlevel = 0;
    fold_T      *fp;

    fp = (fold_T *)gap->ga_data;
    for (i = 0; i < gap->ga_len; ++i)
    {
        level = getDeepestNestingRecurse(&fp[i].fd_nested) + 1;
        if (level > maxlevel)
            maxlevel = level;
    }

    return maxlevel;
}

/* check_closed() {{{2 */
/*
 * Check if a fold is closed and update the info needed to check nested folds.
 */
    static int
check_closed(win, fp, use_levelp, level, maybe_smallp, lnum_off)
    win_T       *win;
    fold_T      *fp;
    int         *use_levelp;        /* TRUE: outer fold had FD_LEVEL */
    int         level;              /* folding depth */
    int         *maybe_smallp;      /* TRUE: outer this had fd_small == MAYBE */
    linenr_T    lnum_off;           /* line number offset for fp->fd_top */
{
    int         closed = FALSE;

    /* Check if this fold is closed.  If the flag is FD_LEVEL this
     * fold and all folds it contains depend on 'foldlevel'. */
    if (*use_levelp || fp->fd_flags == FD_LEVEL)
    {
        *use_levelp = TRUE;
        if (level >= win->w_p_fdl)
            closed = TRUE;
    }
    else if (fp->fd_flags == FD_CLOSED)
        closed = TRUE;

    /* Small fold isn't closed anyway. */
    if (fp->fd_small == MAYBE)
        *maybe_smallp = TRUE;
    if (closed)
    {
        if (*maybe_smallp)
            fp->fd_small = MAYBE;
        checkSmall(win, fp, lnum_off);
        if (fp->fd_small == TRUE)
            closed = FALSE;
    }
    return closed;
}

/* checkSmall() {{{2 */
/*
 * Update fd_small field of fold "fp".
 */
    static void
checkSmall(wp, fp, lnum_off)
    win_T       *wp;
    fold_T      *fp;
    linenr_T    lnum_off;       /* offset for fp->fd_top */
{
    int         count;
    int         n;

    if (fp->fd_small == MAYBE)
    {
        /* Mark any nested folds to maybe-small */
        setSmallMaybe(&fp->fd_nested);

        if (fp->fd_len > curwin->w_p_fml)
            fp->fd_small = FALSE;
        else
        {
            count = 0;
            for (n = 0; n < fp->fd_len; ++n)
            {
                count += plines_win_nofold(wp, fp->fd_top + lnum_off + n);
                if (count > curwin->w_p_fml)
                {
                    fp->fd_small = FALSE;
                    return;
                }
            }
            fp->fd_small = TRUE;
        }
    }
}

/* setSmallMaybe() {{{2 */
/*
 * Set small flags in "gap" to MAYBE.
 */
    static void
setSmallMaybe(gap)
    garray_T    *gap;
{
    int         i;
    fold_T      *fp;

    fp = (fold_T *)gap->ga_data;
    for (i = 0; i < gap->ga_len; ++i)
        fp[i].fd_small = MAYBE;
}

/* foldCreateMarkers() {{{2 */
/*
 * Create a fold from line "start" to line "end" (inclusive) in the current
 * window by adding markers.
 */
    static void
foldCreateMarkers(start, end)
    linenr_T    start;
    linenr_T    end;
{
    if (!curbuf->b_p_ma)
    {
        EMSG(_(e_modifiable));
        return;
    }
    parseMarker(curwin);

    foldAddMarker(start, curwin->w_p_fmr, foldstartmarkerlen);
    foldAddMarker(end, foldendmarker, foldendmarkerlen);

    /* Update both changes here, to avoid all folds after the start are
     * changed when the start marker is inserted and the end isn't. */
    changed_lines(start, (colnr_T)0, end, 0L);
}

/* foldAddMarker() {{{2 */
/*
 * Add "marker[markerlen]" in 'commentstring' to line "lnum".
 */
    static void
foldAddMarker(lnum, marker, markerlen)
    linenr_T    lnum;
    char_u      *marker;
    int         markerlen;
{
    char_u      *cms = curbuf->b_p_cms;
    char_u      *line;
    int         line_len;
    char_u      *newline;
    char_u      *p = (char_u *)strstr((char *)curbuf->b_p_cms, "%s");

    /* Allocate a new line: old-line + 'cms'-start + marker + 'cms'-end */
    line = ml_get(lnum);
    line_len = (int)STRLEN(line);

    if (u_save(lnum - 1, lnum + 1) == OK)
    {
        newline = alloc((unsigned)(line_len + markerlen + STRLEN(cms) + 1));
        if (newline == NULL)
            return;
        STRCPY(newline, line);
        if (p == NULL)
            vim_strncpy(newline + line_len, marker, markerlen);
        else
        {
            STRCPY(newline + line_len, cms);
            STRNCPY(newline + line_len + (p - cms), marker, markerlen);
            STRCPY(newline + line_len + (p - cms) + markerlen, p + 2);
        }

        ml_replace(lnum, newline, FALSE);
    }
}

/* deleteFoldMarkers() {{{2 */
/*
 * Delete the markers for a fold, causing it to be deleted.
 */
    static void
deleteFoldMarkers(fp, recursive, lnum_off)
    fold_T      *fp;
    int         recursive;
    linenr_T    lnum_off;       /* offset for fp->fd_top */
{
    int         i;

    if (recursive)
        for (i = 0; i < fp->fd_nested.ga_len; ++i)
            deleteFoldMarkers((fold_T *)fp->fd_nested.ga_data + i, TRUE,
                                                       lnum_off + fp->fd_top);
    foldDelMarker(fp->fd_top + lnum_off, curwin->w_p_fmr, foldstartmarkerlen);
    foldDelMarker(fp->fd_top + lnum_off + fp->fd_len - 1,
                                             foldendmarker, foldendmarkerlen);
}

/* foldDelMarker() {{{2 */
/*
 * Delete marker "marker[markerlen]" at the end of line "lnum".
 * Delete 'commentstring' if it matches.
 * If the marker is not found, there is no error message.  Could a missing
 * close-marker.
 */
    static void
foldDelMarker(lnum, marker, markerlen)
    linenr_T    lnum;
    char_u      *marker;
    int         markerlen;
{
    char_u      *line;
    char_u      *newline;
    char_u      *p;
    int         len;
    char_u      *cms = curbuf->b_p_cms;
    char_u      *cms2;

    line = ml_get(lnum);
    for (p = line; *p != NUL; ++p)
        if (STRNCMP(p, marker, markerlen) == 0)
        {
            /* Found the marker, include a digit if it's there. */
            len = markerlen;
            if (VIM_ISDIGIT(p[len]))
                ++len;
            if (*cms != NUL)
            {
                /* Also delete 'commentstring' if it matches. */
                cms2 = (char_u *)strstr((char *)cms, "%s");
                if (p - line >= cms2 - cms
                        && STRNCMP(p - (cms2 - cms), cms, cms2 - cms) == 0
                        && STRNCMP(p + len, cms2 + 2, STRLEN(cms2 + 2)) == 0)
                {
                    p -= cms2 - cms;
                    len += (int)STRLEN(cms) - 2;
                }
            }
            if (u_save(lnum - 1, lnum + 1) == OK)
            {
                /* Make new line: text-before-marker + text-after-marker */
                newline = alloc((unsigned)(STRLEN(line) - len + 1));
                if (newline != NULL)
                {
                    STRNCPY(newline, line, p - line);
                    STRCPY(newline + (p - line), p + len);
                    ml_replace(lnum, newline, FALSE);
                }
            }
            break;
        }
}

/* get_foldtext() {{{2 */
/*
 * Return the text for a closed fold at line "lnum", with last line "lnume".
 * When 'foldtext' isn't set puts the result in "buf[51]".  Otherwise the
 * result is in allocated memory.
 */
    char_u *
get_foldtext(wp, lnum, lnume, foldinfo, buf)
    win_T       *wp;
    linenr_T    lnum, lnume;
    foldinfo_T  *foldinfo;
    char_u      *buf;
{
    char_u      *text = NULL;

#ifdef FEAT_EVAL
    if (*wp->w_p_fdt != NUL)
    {
        char_u  dashes[MAX_LEVEL + 2];
        win_T   *save_curwin;
        int     level;
        char_u  *p;

        /* Set "v:foldstart" and "v:foldend". */
        set_vim_var_nr(VV_FOLDSTART, lnum);
        set_vim_var_nr(VV_FOLDEND, lnume);

        /* Set "v:folddashes" to a string of "level" dashes. */
        /* Set "v:foldlevel" to "level". */
        level = foldinfo->fi_level;
        if (level > (int)sizeof(dashes) - 1)
            level = (int)sizeof(dashes) - 1;
        vim_memset(dashes, '-', (size_t)level);
        dashes[level] = NUL;
        set_vim_var_string(VV_FOLDDASHES, dashes, -1);
        set_vim_var_nr(VV_FOLDLEVEL, (long)level);
        save_curwin = curwin;
        curwin = wp;
        curbuf = wp->w_buffer;

        ++emsg_off;
        text = eval_to_string_safe(wp->w_p_fdt, NULL,
                         was_set_insecurely((char_u *)"foldtext", OPT_LOCAL));
        --emsg_off;

        curwin = save_curwin;
        curbuf = curwin->w_buffer;
        set_vim_var_string(VV_FOLDDASHES, NULL, -1);

        if (text != NULL)
        {
            /* Replace unprintable characters, if there are any.  But
             * replace a TAB with a space. */
            for (p = text; *p != NUL; ++p)
            {
# ifdef FEAT_MBYTE
                int     len;

                if (has_mbyte && (len = (*mb_ptr2len)(p)) > 1)
                {
                    if (!vim_isprintc((*mb_ptr2char)(p)))
                        break;
                    p += len - 1;
                }
                else
# endif
                    if (*p == TAB)
                        *p = ' ';
                    else if (ptr2cells(p) > 1)
                        break;
            }
            if (*p != NUL)
            {
                p = transstr(text);
                vim_free(text);
                text = p;
            }
        }
    }
    if (text == NULL)
#endif
    {
        sprintf((char *)buf, _("+--%3ld lines folded "),
                                                    (long)(lnume - lnum + 1));
        text = buf;
    }
    return text;
}

/* foldtext_cleanup() {{{2 */
/*
 * Remove 'foldmarker' and 'commentstring' from "str" (in-place).
 */
    void
foldtext_cleanup(str)
    char_u      *str;
{
    char_u      *cms_start;     /* first part or the whole comment */
    int         cms_slen = 0;   /* length of cms_start */
    char_u      *cms_end;       /* last part of the comment or NULL */
    int         cms_elen = 0;   /* length of cms_end */
    char_u      *s;
    char_u      *p;
    int         len;
    int         did1 = FALSE;
    int         did2 = FALSE;

    /* Ignore leading and trailing white space in 'commentstring'. */
    cms_start = skipwhite(curbuf->b_p_cms);
    cms_slen = (int)STRLEN(cms_start);
    while (cms_slen > 0 && vim_iswhite(cms_start[cms_slen - 1]))
        --cms_slen;

    /* locate "%s" in 'commentstring', use the part before and after it. */
    cms_end = (char_u *)strstr((char *)cms_start, "%s");
    if (cms_end != NULL)
    {
        cms_elen = cms_slen - (int)(cms_end - cms_start);
        cms_slen = (int)(cms_end - cms_start);

        /* exclude white space before "%s" */
        while (cms_slen > 0 && vim_iswhite(cms_start[cms_slen - 1]))
            --cms_slen;

        /* skip "%s" and white space after it */
        s = skipwhite(cms_end + 2);
        cms_elen -= (int)(s - cms_end);
        cms_end = s;
    }
    parseMarker(curwin);

    for (s = str; *s != NUL; )
    {
        len = 0;
        if (STRNCMP(s, curwin->w_p_fmr, foldstartmarkerlen) == 0)
            len = foldstartmarkerlen;
        else if (STRNCMP(s, foldendmarker, foldendmarkerlen) == 0)
            len = foldendmarkerlen;
        if (len > 0)
        {
            if (VIM_ISDIGIT(s[len]))
                ++len;

            /* May remove 'commentstring' start.  Useful when it's a double
             * quote and we already removed a double quote. */
            for (p = s; p > str && vim_iswhite(p[-1]); --p)
                ;
            if (p >= str + cms_slen
                           && STRNCMP(p - cms_slen, cms_start, cms_slen) == 0)
            {
                len += (int)(s - p) + cms_slen;
                s = p - cms_slen;
            }
        }
        else if (cms_end != NULL)
        {
            if (!did1 && cms_slen > 0 && STRNCMP(s, cms_start, cms_slen) == 0)
            {
                len = cms_slen;
                did1 = TRUE;
            }
            else if (!did2 && cms_elen > 0
                                        && STRNCMP(s, cms_end, cms_elen) == 0)
            {
                len = cms_elen;
                did2 = TRUE;
            }
        }
        if (len != 0)
        {
            while (vim_iswhite(s[len]))
                ++len;
            STRMOVE(s, s + len);
        }
        else
        {
            mb_ptr_adv(s);
        }
    }
}

/* Folding by indent, expr, marker and syntax. {{{1 */
/* Define "fline_T", passed to get fold level for a line. {{{2 */
typedef struct
{
    win_T       *wp;            /* window */
    linenr_T    lnum;           /* current line number */
    linenr_T    off;            /* offset between lnum and real line number */
    linenr_T    lnum_save;      /* line nr used by foldUpdateIEMSRecurse() */
    int         lvl;            /* current level (-1 for undefined) */
    int         lvl_next;       /* level used for next line */
    int         start;          /* number of folds that are forced to start at
                                   this line. */
    int         end;            /* level of fold that is forced to end below
                                   this line */
    int         had_end;        /* level of fold that is forced to end above
                                   this line (copy of "end" of prev. line) */
} fline_T;

/* Flag is set when redrawing is needed. */
static int fold_changed;

/* Function declarations. {{{2 */
static linenr_T foldUpdateIEMSRecurse __ARGS((garray_T *gap, int level, linenr_T startlnum, fline_T *flp, void (*getlevel)__ARGS((fline_T *)), linenr_T bot, int topflags));
static int foldInsert __ARGS((garray_T *gap, int i));
static void foldSplit __ARGS((garray_T *gap, int i, linenr_T top, linenr_T bot));
static void foldRemove __ARGS((garray_T *gap, linenr_T top, linenr_T bot));
static void foldMerge __ARGS((fold_T *fp1, garray_T *gap, fold_T *fp2));
static void foldlevelIndent __ARGS((fline_T *flp));
#ifdef FEAT_DIFF
static void foldlevelDiff __ARGS((fline_T *flp));
#endif
static void foldlevelExpr __ARGS((fline_T *flp));
static void foldlevelMarker __ARGS((fline_T *flp));
static void foldlevelSyntax __ARGS((fline_T *flp));

/* foldUpdateIEMS() {{{2 */
/*
 * Update the folding for window "wp", at least from lines "top" to "bot".
 * Return TRUE if any folds did change.
 */
    static void
foldUpdateIEMS(wp, top, bot)
    win_T       *wp;
    linenr_T    top;
    linenr_T    bot;
{
    linenr_T    start;
    linenr_T    end;
    fline_T     fline;
    void        (*getlevel)__ARGS((fline_T *));
    int         level;
    fold_T      *fp;

    /* Avoid problems when being called recursively. */
    if (invalid_top != (linenr_T)0)
        return;

    if (wp->w_foldinvalid)
    {
        /* Need to update all folds. */
        top = 1;
        bot = wp->w_buffer->b_ml.ml_line_count;
        wp->w_foldinvalid = FALSE;

        /* Mark all folds a maybe-small. */
        setSmallMaybe(&wp->w_folds);
    }

#ifdef FEAT_DIFF
    /* add the context for "diff" folding */
    if (foldmethodIsDiff(wp))
    {
        if (top > diff_context)
            top -= diff_context;
        else
            top = 1;
        bot += diff_context;
    }
#endif

    /* When deleting lines at the end of the buffer "top" can be past the end
     * of the buffer. */
    if (top > wp->w_buffer->b_ml.ml_line_count)
        top = wp->w_buffer->b_ml.ml_line_count;

    fold_changed = FALSE;
    fline.wp = wp;
    fline.off = 0;
    fline.lvl = 0;
    fline.lvl_next = -1;
    fline.start = 0;
    fline.end = MAX_LEVEL + 1;
    fline.had_end = MAX_LEVEL + 1;

    invalid_top = top;
    invalid_bot = bot;

    if (foldmethodIsMarker(wp))
    {
        getlevel = foldlevelMarker;

        /* Init marker variables to speed up foldlevelMarker(). */
        parseMarker(wp);

        /* Need to get the level of the line above top, it is used if there is
         * no marker at the top. */
        if (top > 1)
        {
            /* Get the fold level at top - 1. */
            level = foldLevelWin(wp, top - 1);

            /* The fold may end just above the top, check for that. */
            fline.lnum = top - 1;
            fline.lvl = level;
            getlevel(&fline);

            /* If a fold started here, we already had the level, if it stops
             * here, we need to use lvl_next.  Could also start and end a fold
             * in the same line. */
            if (fline.lvl > level)
                fline.lvl = level - (fline.lvl - fline.lvl_next);
            else
                fline.lvl = fline.lvl_next;
        }
        fline.lnum = top;
        getlevel(&fline);
    }
    else
    {
        fline.lnum = top;
        if (foldmethodIsExpr(wp))
        {
            getlevel = foldlevelExpr;
            /* start one line back, because a "<1" may indicate the end of a
             * fold in the topline */
            if (top > 1)
                --fline.lnum;
        }
        else if (foldmethodIsSyntax(wp))
            getlevel = foldlevelSyntax;
#ifdef FEAT_DIFF
        else if (foldmethodIsDiff(wp))
            getlevel = foldlevelDiff;
#endif
        else
            getlevel = foldlevelIndent;

        /* Backup to a line for which the fold level is defined.  Since it's
         * always defined for line one, we will stop there. */
        fline.lvl = -1;
        for ( ; !got_int; --fline.lnum)
        {
            /* Reset lvl_next each time, because it will be set to a value for
             * the next line, but we search backwards here. */
            fline.lvl_next = -1;
            getlevel(&fline);
            if (fline.lvl >= 0)
                break;
        }
    }

    /*
     * If folding is defined by the syntax, it is possible that a change in
     * one line will cause all sub-folds of the current fold to change (e.g.,
     * closing a C-style comment can cause folds in the subsequent lines to
     * appear). To take that into account we should adjust the value of "bot"
     * to point to the end of the current fold:
     */
    if (foldlevelSyntax == getlevel)
    {
        garray_T *gap = &wp->w_folds;
        fold_T   *fp = NULL;
        int       current_fdl = 0;
        linenr_T  fold_start_lnum = 0;
        linenr_T  lnum_rel = fline.lnum;

        while (current_fdl < fline.lvl)
        {
            if (!foldFind(gap, lnum_rel, &fp))
                break;
            ++current_fdl;

            fold_start_lnum += fp->fd_top;
            gap = &fp->fd_nested;
            lnum_rel -= fp->fd_top;
        }
        if (fp != NULL && current_fdl == fline.lvl)
        {
            linenr_T fold_end_lnum = fold_start_lnum + fp->fd_len;

            if (fold_end_lnum > bot)
                bot = fold_end_lnum;
        }
    }

    start = fline.lnum;
    end = bot;
    /* Do at least one line. */
    if (start > end && end < wp->w_buffer->b_ml.ml_line_count)
        end = start;
    while (!got_int)
    {
        /* Always stop at the end of the file ("end" can be past the end of
         * the file). */
        if (fline.lnum > wp->w_buffer->b_ml.ml_line_count)
            break;
        if (fline.lnum > end)
        {
            /* For "marker", "expr"  and "syntax"  methods: If a change caused
             * a fold to be removed, we need to continue at least until where
             * it ended. */
            if (getlevel != foldlevelMarker
                    && getlevel != foldlevelSyntax
                    && getlevel != foldlevelExpr)
                break;
            if ((start <= end
                        && foldFind(&wp->w_folds, end, &fp)
                        && fp->fd_top + fp->fd_len - 1 > end)
                    || (fline.lvl == 0
                        && foldFind(&wp->w_folds, fline.lnum, &fp)
                        && fp->fd_top < fline.lnum))
                end = fp->fd_top + fp->fd_len - 1;
            else if (getlevel == foldlevelSyntax
                    && foldLevelWin(wp, fline.lnum) != fline.lvl)
                /* For "syntax" method: Compare the foldlevel that the syntax
                 * tells us to the foldlevel from the existing folds.  If they
                 * don't match continue updating folds. */
                end = fline.lnum;
            else
                break;
        }

        /* A level 1 fold starts at a line with foldlevel > 0. */
        if (fline.lvl > 0)
        {
            invalid_top = fline.lnum;
            invalid_bot = end;
            end = foldUpdateIEMSRecurse(&wp->w_folds,
                                   1, start, &fline, getlevel, end, FD_LEVEL);
            start = fline.lnum;
        }
        else
        {
            if (fline.lnum == wp->w_buffer->b_ml.ml_line_count)
                break;
            ++fline.lnum;
            fline.lvl = fline.lvl_next;
            getlevel(&fline);
        }
    }

    /* There can't be any folds from start until end now. */
    foldRemove(&wp->w_folds, start, end);

    /* If some fold changed, need to redraw and position cursor. */
    if (fold_changed && wp->w_p_fen)
        changed_window_setting_win(wp);

    /* If we updated folds past "bot", need to redraw more lines.  Don't do
     * this in other situations, the changed lines will be redrawn anyway and
     * this method can cause the whole window to be updated. */
    if (end != bot)
    {
        if (wp->w_redraw_top == 0 || wp->w_redraw_top > top)
            wp->w_redraw_top = top;
        if (wp->w_redraw_bot < end)
            wp->w_redraw_bot = end;
    }

    invalid_top = (linenr_T)0;
}

/* foldUpdateIEMSRecurse() {{{2 */
/*
 * Update a fold that starts at "flp->lnum".  At this line there is always a
 * valid foldlevel, and its level >= "level".
 * "flp" is valid for "flp->lnum" when called and it's valid when returning.
 * "flp->lnum" is set to the lnum just below the fold, if it ends before
 * "bot", it's "bot" plus one if the fold continues and it's bigger when using
 * the marker method and a text change made following folds to change.
 * When returning, "flp->lnum_save" is the line number that was used to get
 * the level when the level at "flp->lnum" is invalid.
 * Remove any folds from "startlnum" up to here at this level.
 * Recursively update nested folds.
 * Below line "bot" there are no changes in the text.
 * "flp->lnum", "flp->lnum_save" and "bot" are relative to the start of the
 * outer fold.
 * "flp->off" is the offset to the real line number in the buffer.
 *
 * All this would be a lot simpler if all folds in the range would be deleted
 * and then created again.  But we would lose all information about the
 * folds, even when making changes that don't affect the folding (e.g. "vj~").
 *
 * Returns bot, which may have been increased for lines that also need to be
 * updated as a result of a detected change in the fold.
 */
    static linenr_T
foldUpdateIEMSRecurse(gap, level, startlnum, flp, getlevel, bot, topflags)
    garray_T    *gap;
    int         level;
    linenr_T    startlnum;
    fline_T     *flp;
    void        (*getlevel)__ARGS((fline_T *));
    linenr_T    bot;
    int         topflags;       /* flags used by containing fold */
{
    linenr_T    ll;
    fold_T      *fp = NULL;
    fold_T      *fp2;
    int         lvl = level;
    linenr_T    startlnum2 = startlnum;
    linenr_T    firstlnum = flp->lnum;  /* first lnum we got */
    int         i;
    int         finish = FALSE;
    linenr_T    linecount = flp->wp->w_buffer->b_ml.ml_line_count - flp->off;
    int         concat;

    /*
     * If using the marker method, the start line is not the start of a fold
     * at the level we're dealing with and the level is non-zero, we must use
     * the previous fold.  But ignore a fold that starts at or below
     * startlnum, it must be deleted.
     */
    if (getlevel == foldlevelMarker && flp->start <= flp->lvl - level
                                                              && flp->lvl > 0)
    {
        foldFind(gap, startlnum - 1, &fp);
        if (fp >= ((fold_T *)gap->ga_data) + gap->ga_len
                                                   || fp->fd_top >= startlnum)
            fp = NULL;
    }

    /*
     * Loop over all lines in this fold, or until "bot" is hit.
     * Handle nested folds inside of this fold.
     * "flp->lnum" is the current line.  When finding the end of the fold, it
     * is just below the end of the fold.
     * "*flp" contains the level of the line "flp->lnum" or a following one if
     * there are lines with an invalid fold level.  "flp->lnum_save" is the
     * line number that was used to get the fold level (below "flp->lnum" when
     * it has an invalid fold level).  When called the fold level is always
     * valid, thus "flp->lnum_save" is equal to "flp->lnum".
     */
    flp->lnum_save = flp->lnum;
    while (!got_int)
    {
        /* Updating folds can be slow, check for CTRL-C. */
        line_breakcheck();

        /* Set "lvl" to the level of line "flp->lnum".  When flp->start is set
         * and after the first line of the fold, set the level to zero to
         * force the fold to end.  Do the same when had_end is set: Previous
         * line was marked as end of a fold. */
        lvl = flp->lvl;
        if (lvl > MAX_LEVEL)
            lvl = MAX_LEVEL;
        if (flp->lnum > firstlnum
                && (level > lvl - flp->start || level >= flp->had_end))
            lvl = 0;

        if (flp->lnum > bot && !finish && fp != NULL)
        {
            /* For "marker" and "syntax" methods:
             * - If a change caused a nested fold to be removed, we need to
             *   delete it and continue at least until where it ended.
             * - If a change caused a nested fold to be created, or this fold
             *   to continue below its original end, need to finish this fold.
             */
            if (getlevel != foldlevelMarker
                    && getlevel != foldlevelExpr
                    && getlevel != foldlevelSyntax)
                break;
            i = 0;
            fp2 = fp;
            if (lvl >= level)
            {
                /* Compute how deep the folds currently are, if it's deeper
                 * than "lvl" then some must be deleted, need to update
                 * at least one nested fold. */
                ll = flp->lnum - fp->fd_top;
                while (foldFind(&fp2->fd_nested, ll, &fp2))
                {
                    ++i;
                    ll -= fp2->fd_top;
                }
            }
            if (lvl < level + i)
            {
                foldFind(&fp->fd_nested, flp->lnum - fp->fd_top, &fp2);
                if (fp2 != NULL)
                    bot = fp2->fd_top + fp2->fd_len - 1 + fp->fd_top;
            }
            else if (fp->fd_top + fp->fd_len <= flp->lnum && lvl >= level)
                finish = TRUE;
            else
                break;
        }

        /* At the start of the first nested fold and at the end of the current
         * fold: check if existing folds at this level, before the current
         * one, need to be deleted or truncated. */
        if (fp == NULL
                && (lvl != level
                    || flp->lnum_save >= bot
                    || flp->start != 0
                    || flp->had_end <= MAX_LEVEL
                    || flp->lnum == linecount))
        {
            /*
             * Remove or update folds that have lines between startlnum and
             * firstlnum.
             */
            while (!got_int)
            {
                /* set concat to 1 if it's allowed to concatenated this fold
                 * with a previous one that touches it. */
                if (flp->start != 0 || flp->had_end <= MAX_LEVEL)
                    concat = 0;
                else
                    concat = 1;

                /* Find an existing fold to re-use.  Preferably one that
                 * includes startlnum, otherwise one that ends just before
                 * startlnum or starts after it. */
                if (foldFind(gap, startlnum, &fp)
                        || (fp < ((fold_T *)gap->ga_data) + gap->ga_len
                            && fp->fd_top <= firstlnum)
                        || foldFind(gap, firstlnum - concat, &fp)
                        || (fp < ((fold_T *)gap->ga_data) + gap->ga_len
                            && ((lvl < level && fp->fd_top < flp->lnum)
                                || (lvl >= level
                                           && fp->fd_top <= flp->lnum_save))))
                {
                    if (fp->fd_top + fp->fd_len + concat > firstlnum)
                    {
                        /* Use existing fold for the new fold.  If it starts
                         * before where we started looking, extend it.  If it
                         * starts at another line, update nested folds to keep
                         * their position, compensating for the new fd_top. */
                        if (fp->fd_top >= startlnum && fp->fd_top != firstlnum)
                        {
                            if (fp->fd_top > firstlnum)
                                /* like lines are inserted */
                                foldMarkAdjustRecurse(&fp->fd_nested,
                                        (linenr_T)0, (linenr_T)MAXLNUM,
                                        (long)(fp->fd_top - firstlnum), 0L);
                            else
                                /* like lines are deleted */
                                foldMarkAdjustRecurse(&fp->fd_nested,
                                        (linenr_T)0,
                                        (long)(firstlnum - fp->fd_top - 1),
                                        (linenr_T)MAXLNUM,
                                        (long)(fp->fd_top - firstlnum));
                            fp->fd_len += fp->fd_top - firstlnum;
                            fp->fd_top = firstlnum;
                            fold_changed = TRUE;
                        }
                        else if (flp->start != 0 && lvl == level
                                                   && fp->fd_top != firstlnum)
                        {
                            /* Existing fold that includes startlnum must stop
                             * if we find the start of a new fold at the same
                             * level.  Split it.  Delete contained folds at
                             * this point to split them too. */
                            foldRemove(&fp->fd_nested, flp->lnum - fp->fd_top,
                                                      flp->lnum - fp->fd_top);
                            i = (int)(fp - (fold_T *)gap->ga_data);
                            foldSplit(gap, i, flp->lnum, flp->lnum - 1);
                            fp = (fold_T *)gap->ga_data + i + 1;
                            /* If using the "marker" or "syntax" method, we
                             * need to continue until the end of the fold is
                             * found. */
                            if (getlevel == foldlevelMarker
                                    || getlevel == foldlevelExpr
                                    || getlevel == foldlevelSyntax)
                                finish = TRUE;
                        }
                        break;
                    }
                    if (fp->fd_top >= startlnum)
                    {
                        /* A fold that starts at or after startlnum and stops
                         * before the new fold must be deleted.  Continue
                         * looking for the next one. */
                        deleteFoldEntry(gap,
                                     (int)(fp - (fold_T *)gap->ga_data), TRUE);
                    }
                    else
                    {
                        /* A fold has some lines above startlnum, truncate it
                         * to stop just above startlnum.  */
                        fp->fd_len = startlnum - fp->fd_top;
                        foldMarkAdjustRecurse(&fp->fd_nested,
                                (linenr_T)fp->fd_len, (linenr_T)MAXLNUM,
                                                       (linenr_T)MAXLNUM, 0L);
                        fold_changed = TRUE;
                    }
                }
                else
                {
                    /* Insert new fold.  Careful: ga_data may be NULL and it
                     * may change! */
                    i = (int)(fp - (fold_T *)gap->ga_data);
                    if (foldInsert(gap, i) != OK)
                        return bot;
                    fp = (fold_T *)gap->ga_data + i;
                    /* The new fold continues until bot, unless we find the
                     * end earlier. */
                    fp->fd_top = firstlnum;
                    fp->fd_len = bot - firstlnum + 1;
                    /* When the containing fold is open, the new fold is open.
                     * The new fold is closed if the fold above it is closed.
                     * The first fold depends on the containing fold. */
                    if (topflags == FD_OPEN)
                    {
                        flp->wp->w_fold_manual = TRUE;
                        fp->fd_flags = FD_OPEN;
                    }
                    else if (i <= 0)
                    {
                        fp->fd_flags = topflags;
                        if (topflags != FD_LEVEL)
                            flp->wp->w_fold_manual = TRUE;
                    }
                    else
                        fp->fd_flags = (fp - 1)->fd_flags;
                    fp->fd_small = MAYBE;
                    /* If using the "marker", "expr" or "syntax" method, we
                     * need to continue until the end of the fold is found. */
                    if (getlevel == foldlevelMarker
                            || getlevel == foldlevelExpr
                            || getlevel == foldlevelSyntax)
                        finish = TRUE;
                    fold_changed = TRUE;
                    break;
                }
            }
        }

        if (lvl < level || flp->lnum > linecount)
        {
            /*
             * Found a line with a lower foldlevel, this fold ends just above
             * "flp->lnum".
             */
            break;
        }

        /*
         * The fold includes the line "flp->lnum" and "flp->lnum_save".
         * Check "fp" for safety.
         */
        if (lvl > level && fp != NULL)
        {
            /*
             * There is a nested fold, handle it recursively.
             */
            /* At least do one line (can happen when finish is TRUE). */
            if (bot < flp->lnum)
                bot = flp->lnum;

            /* Line numbers in the nested fold are relative to the start of
             * this fold. */
            flp->lnum = flp->lnum_save - fp->fd_top;
            flp->off += fp->fd_top;
            i = (int)(fp - (fold_T *)gap->ga_data);
            bot = foldUpdateIEMSRecurse(&fp->fd_nested, level + 1,
                                       startlnum2 - fp->fd_top, flp, getlevel,
                                              bot - fp->fd_top, fp->fd_flags);
            fp = (fold_T *)gap->ga_data + i;
            flp->lnum += fp->fd_top;
            flp->lnum_save += fp->fd_top;
            flp->off -= fp->fd_top;
            bot += fp->fd_top;
            startlnum2 = flp->lnum;

            /* This fold may end at the same line, don't incr. flp->lnum. */
        }
        else
        {
            /*
             * Get the level of the next line, then continue the loop to check
             * if it ends there.
             * Skip over undefined lines, to find the foldlevel after it.
             * For the last line in the file the foldlevel is always valid.
             */
            flp->lnum = flp->lnum_save;
            ll = flp->lnum + 1;
            while (!got_int)
            {
                /* Make the previous level available to foldlevel(). */
                prev_lnum = flp->lnum;
                prev_lnum_lvl = flp->lvl;

                if (++flp->lnum > linecount)
                    break;
                flp->lvl = flp->lvl_next;
                getlevel(flp);
                if (flp->lvl >= 0 || flp->had_end <= MAX_LEVEL)
                    break;
            }
            prev_lnum = 0;
            if (flp->lnum > linecount)
                break;

            /* leave flp->lnum_save to lnum of the line that was used to get
             * the level, flp->lnum to the lnum of the next line. */
            flp->lnum_save = flp->lnum;
            flp->lnum = ll;
        }
    }

    if (fp == NULL)     /* only happens when got_int is set */
        return bot;

    /*
     * Get here when:
     * lvl < level: the folds ends just above "flp->lnum"
     * lvl >= level: fold continues below "bot"
     */

    /* Current fold at least extends until lnum. */
    if (fp->fd_len < flp->lnum - fp->fd_top)
    {
        fp->fd_len = flp->lnum - fp->fd_top;
        fp->fd_small = MAYBE;
        fold_changed = TRUE;
    }

    /* Delete contained folds from the end of the last one found until where
     * we stopped looking. */
    foldRemove(&fp->fd_nested, startlnum2 - fp->fd_top,
                                                  flp->lnum - 1 - fp->fd_top);

    if (lvl < level)
    {
        /* End of fold found, update the length when it got shorter. */
        if (fp->fd_len != flp->lnum - fp->fd_top)
        {
            if (fp->fd_top + fp->fd_len > bot + 1)
            {
                /* fold continued below bot */
                if (getlevel == foldlevelMarker
                        || getlevel == foldlevelExpr
                        || getlevel == foldlevelSyntax)
                {
                    /* marker method: truncate the fold and make sure the
                     * previously included lines are processed again */
                    bot = fp->fd_top + fp->fd_len - 1;
                    fp->fd_len = flp->lnum - fp->fd_top;
                }
                else
                {
                    /* indent or expr method: split fold to create a new one
                     * below bot */
                    i = (int)(fp - (fold_T *)gap->ga_data);
                    foldSplit(gap, i, flp->lnum, bot);
                    fp = (fold_T *)gap->ga_data + i;
                }
            }
            else
                fp->fd_len = flp->lnum - fp->fd_top;
            fold_changed = TRUE;
        }
    }

    /* delete following folds that end before the current line */
    for (;;)
    {
        fp2 = fp + 1;
        if (fp2 >= (fold_T *)gap->ga_data + gap->ga_len
                                                  || fp2->fd_top > flp->lnum)
            break;
        if (fp2->fd_top + fp2->fd_len > flp->lnum)
        {
            if (fp2->fd_top < flp->lnum)
            {
                /* Make fold that includes lnum start at lnum. */
                foldMarkAdjustRecurse(&fp2->fd_nested,
                        (linenr_T)0, (long)(flp->lnum - fp2->fd_top - 1),
                        (linenr_T)MAXLNUM, (long)(fp2->fd_top - flp->lnum));
                fp2->fd_len -= flp->lnum - fp2->fd_top;
                fp2->fd_top = flp->lnum;
                fold_changed = TRUE;
            }

            if (lvl >= level)
            {
                /* merge new fold with existing fold that follows */
                foldMerge(fp, gap, fp2);
            }
            break;
        }
        fold_changed = TRUE;
        deleteFoldEntry(gap, (int)(fp2 - (fold_T *)gap->ga_data), TRUE);
    }

    /* Need to redraw the lines we inspected, which might be further down than
     * was asked for. */
    if (bot < flp->lnum - 1)
        bot = flp->lnum - 1;

    return bot;
}

/* foldInsert() {{{2 */
/*
 * Insert a new fold in "gap" at position "i".
 * Returns OK for success, FAIL for failure.
 */
    static int
foldInsert(gap, i)
    garray_T    *gap;
    int         i;
{
    fold_T      *fp;

    if (ga_grow(gap, 1) != OK)
        return FAIL;
    fp = (fold_T *)gap->ga_data + i;
    if (i < gap->ga_len)
        mch_memmove(fp + 1, fp, sizeof(fold_T) * (gap->ga_len - i));
    ++gap->ga_len;
    ga_init2(&fp->fd_nested, (int)sizeof(fold_T), 10);
    return OK;
}

/* foldSplit() {{{2 */
/*
 * Split the "i"th fold in "gap", which starts before "top" and ends below
 * "bot" in two pieces, one ending above "top" and the other starting below
 * "bot".
 * The caller must first have taken care of any nested folds from "top" to
 * "bot"!
 */
    static void
foldSplit(gap, i, top, bot)
    garray_T    *gap;
    int         i;
    linenr_T    top;
    linenr_T    bot;
{
    fold_T      *fp;
    fold_T      *fp2;
    garray_T    *gap1;
    garray_T    *gap2;
    int         idx;
    int         len;

    /* The fold continues below bot, need to split it. */
    if (foldInsert(gap, i + 1) == FAIL)
        return;
    fp = (fold_T *)gap->ga_data + i;
    fp[1].fd_top = bot + 1;
    fp[1].fd_len = fp->fd_len - (fp[1].fd_top - fp->fd_top);
    fp[1].fd_flags = fp->fd_flags;
    fp[1].fd_small = MAYBE;
    fp->fd_small = MAYBE;

    /* Move nested folds below bot to new fold.  There can't be
     * any between top and bot, they have been removed by the caller. */
    gap1 = &fp->fd_nested;
    gap2 = &fp[1].fd_nested;
    (void)(foldFind(gap1, bot + 1 - fp->fd_top, &fp2));
    len = (int)((fold_T *)gap1->ga_data + gap1->ga_len - fp2);
    if (len > 0 && ga_grow(gap2, len) == OK)
    {
        for (idx = 0; idx < len; ++idx)
        {
            ((fold_T *)gap2->ga_data)[idx] = fp2[idx];
            ((fold_T *)gap2->ga_data)[idx].fd_top
                                                 -= fp[1].fd_top - fp->fd_top;
        }
        gap2->ga_len = len;
        gap1->ga_len -= len;
    }
    fp->fd_len = top - fp->fd_top;
    fold_changed = TRUE;
}

/* foldRemove() {{{2 */
/*
 * Remove folds within the range "top" to and including "bot".
 * Check for these situations:
 *      1  2  3
 *      1  2  3
 * top     2  3  4  5
 *         2  3  4  5
 * bot     2  3  4  5
 *            3     5  6
 *            3     5  6
 *
 * 1: not changed
 * 2: truncate to stop above "top"
 * 3: split in two parts, one stops above "top", other starts below "bot".
 * 4: deleted
 * 5: made to start below "bot".
 * 6: not changed
 */
    static void
foldRemove(gap, top, bot)
    garray_T    *gap;
    linenr_T    top;
    linenr_T    bot;
{
    fold_T      *fp = NULL;

    if (bot < top)
        return;         /* nothing to do */

    for (;;)
    {
        /* Find fold that includes top or a following one. */
        if (foldFind(gap, top, &fp) && fp->fd_top < top)
        {
            /* 2: or 3: need to delete nested folds */
            foldRemove(&fp->fd_nested, top - fp->fd_top, bot - fp->fd_top);
            if (fp->fd_top + fp->fd_len > bot + 1)
            {
                /* 3: need to split it. */
                foldSplit(gap, (int)(fp - (fold_T *)gap->ga_data), top, bot);
            }
            else
            {
                /* 2: truncate fold at "top". */
                fp->fd_len = top - fp->fd_top;
            }
            fold_changed = TRUE;
            continue;
        }
        if (fp >= (fold_T *)(gap->ga_data) + gap->ga_len
                || fp->fd_top > bot)
        {
            /* 6: Found a fold below bot, can stop looking. */
            break;
        }
        if (fp->fd_top >= top)
        {
            /* Found an entry below top. */
            fold_changed = TRUE;
            if (fp->fd_top + fp->fd_len - 1 > bot)
            {
                /* 5: Make fold that includes bot start below bot. */
                foldMarkAdjustRecurse(&fp->fd_nested,
                        (linenr_T)0, (long)(bot - fp->fd_top),
                        (linenr_T)MAXLNUM, (long)(fp->fd_top - bot - 1));
                fp->fd_len -= bot - fp->fd_top + 1;
                fp->fd_top = bot + 1;
                break;
            }

            /* 4: Delete completely contained fold. */
            deleteFoldEntry(gap, (int)(fp - (fold_T *)gap->ga_data), TRUE);
        }
    }
}

/* foldMerge() {{{2 */
/*
 * Merge two adjacent folds (and the nested ones in them).
 * This only works correctly when the folds are really adjacent!  Thus "fp1"
 * must end just above "fp2".
 * The resulting fold is "fp1", nested folds are moved from "fp2" to "fp1".
 * Fold entry "fp2" in "gap" is deleted.
 */
    static void
foldMerge(fp1, gap, fp2)
    fold_T      *fp1;
    garray_T    *gap;
    fold_T      *fp2;
{
    fold_T      *fp3;
    fold_T      *fp4;
    int         idx;
    garray_T    *gap1 = &fp1->fd_nested;
    garray_T    *gap2 = &fp2->fd_nested;

    /* If the last nested fold in fp1 touches the first nested fold in fp2,
     * merge them recursively. */
    if (foldFind(gap1, fp1->fd_len - 1L, &fp3) && foldFind(gap2, 0L, &fp4))
        foldMerge(fp3, gap2, fp4);

    /* Move nested folds in fp2 to the end of fp1. */
    if (gap2->ga_len > 0 && ga_grow(gap1, gap2->ga_len) == OK)
    {
        for (idx = 0; idx < gap2->ga_len; ++idx)
        {
            ((fold_T *)gap1->ga_data)[gap1->ga_len]
                                        = ((fold_T *)gap2->ga_data)[idx];
            ((fold_T *)gap1->ga_data)[gap1->ga_len].fd_top += fp1->fd_len;
            ++gap1->ga_len;
        }
        gap2->ga_len = 0;
    }

    fp1->fd_len += fp2->fd_len;
    deleteFoldEntry(gap, (int)(fp2 - (fold_T *)gap->ga_data), TRUE);
    fold_changed = TRUE;
}

/* foldlevelIndent() {{{2 */
/*
 * Low level function to get the foldlevel for the "indent" method.
 * Doesn't use any caching.
 * Returns a level of -1 if the foldlevel depends on surrounding lines.
 */
    static void
foldlevelIndent(flp)
    fline_T     *flp;
{
    char_u      *s;
    buf_T       *buf;
    linenr_T    lnum = flp->lnum + flp->off;

    buf = flp->wp->w_buffer;
    s = skipwhite(ml_get_buf(buf, lnum, FALSE));

    /* empty line or lines starting with a character in 'foldignore': level
     * depends on surrounding lines */
    if (*s == NUL || vim_strchr(flp->wp->w_p_fdi, *s) != NULL)
    {
        /* first and last line can't be undefined, use level 0 */
        if (lnum == 1 || lnum == buf->b_ml.ml_line_count)
            flp->lvl = 0;
        else
            flp->lvl = -1;
    }
    else
        flp->lvl = get_indent_buf(buf, lnum) / buf->b_p_sw;
    if (flp->lvl > flp->wp->w_p_fdn)
    {
        flp->lvl = flp->wp->w_p_fdn;
        if (flp->lvl < 0)
            flp->lvl = 0;
    }
}

/* foldlevelDiff() {{{2 */
#ifdef FEAT_DIFF
/*
 * Low level function to get the foldlevel for the "diff" method.
 * Doesn't use any caching.
 */
    static void
foldlevelDiff(flp)
    fline_T     *flp;
{
    if (diff_infold(flp->wp, flp->lnum + flp->off))
        flp->lvl = 1;
    else
        flp->lvl = 0;
}
#endif

/* foldlevelExpr() {{{2 */
/*
 * Low level function to get the foldlevel for the "expr" method.
 * Doesn't use any caching.
 * Returns a level of -1 if the foldlevel depends on surrounding lines.
 */
    static void
foldlevelExpr(flp)
    fline_T     *flp;
{
#ifndef FEAT_EVAL
    flp->start = FALSE;
    flp->lvl = 0;
#else
    win_T       *win;
    int         n;
    int         c;
    linenr_T    lnum = flp->lnum + flp->off;
    int         save_keytyped;

    win = curwin;
    curwin = flp->wp;
    curbuf = flp->wp->w_buffer;
    set_vim_var_nr(VV_LNUM, lnum);

    flp->start = 0;
    flp->had_end = flp->end;
    flp->end = MAX_LEVEL + 1;
    if (lnum <= 1)
        flp->lvl = 0;

    /* KeyTyped may be reset to 0 when calling a function which invokes
     * do_cmdline().  To make 'foldopen' work correctly restore KeyTyped. */
    save_keytyped = KeyTyped;
    n = eval_foldexpr(flp->wp->w_p_fde, &c);
    KeyTyped = save_keytyped;

    switch (c)
    {
        /* "a1", "a2", .. : add to the fold level */
        case 'a': if (flp->lvl >= 0)
                  {
                      flp->lvl += n;
                      flp->lvl_next = flp->lvl;
                  }
                  flp->start = n;
                  break;

        /* "s1", "s2", .. : subtract from the fold level */
        case 's': if (flp->lvl >= 0)
                  {
                      if (n > flp->lvl)
                          flp->lvl_next = 0;
                      else
                          flp->lvl_next = flp->lvl - n;
                      flp->end = flp->lvl_next + 1;
                  }
                  break;

        /* ">1", ">2", .. : start a fold with a certain level */
        case '>': flp->lvl = n;
                  flp->lvl_next = n;
                  flp->start = 1;
                  break;

        /* "<1", "<2", .. : end a fold with a certain level */
        case '<': flp->lvl_next = n - 1;
                  flp->end = n;
                  break;

        /* "=": No change in level */
        case '=': flp->lvl_next = flp->lvl;
                  break;

        /* "-1", "0", "1", ..: set fold level */
        default:  if (n < 0)
                      /* Use the current level for the next line, so that "a1"
                       * will work there. */
                      flp->lvl_next = flp->lvl;
                  else
                      flp->lvl_next = n;
                  flp->lvl = n;
                  break;
    }

    /* If the level is unknown for the first or the last line in the file, use
     * level 0. */
    if (flp->lvl < 0)
    {
        if (lnum <= 1)
        {
            flp->lvl = 0;
            flp->lvl_next = 0;
        }
        if (lnum == curbuf->b_ml.ml_line_count)
            flp->lvl_next = 0;
    }

    curwin = win;
    curbuf = curwin->w_buffer;
#endif
}

/* parseMarker() {{{2 */
/*
 * Parse 'foldmarker' and set "foldendmarker", "foldstartmarkerlen" and
 * "foldendmarkerlen".
 * Relies on the option value to have been checked for correctness already.
 */
    static void
parseMarker(wp)
    win_T       *wp;
{
    foldendmarker = vim_strchr(wp->w_p_fmr, ',');
    foldstartmarkerlen = (int)(foldendmarker++ - wp->w_p_fmr);
    foldendmarkerlen = (int)STRLEN(foldendmarker);
}

/* foldlevelMarker() {{{2 */
/*
 * Low level function to get the foldlevel for the "marker" method.
 * "foldendmarker", "foldstartmarkerlen" and "foldendmarkerlen" must have been
 * set before calling this.
 * Requires that flp->lvl is set to the fold level of the previous line!
 * Careful: This means you can't call this function twice on the same line.
 * Doesn't use any caching.
 * Sets flp->start when a start marker was found.
 */
    static void
foldlevelMarker(flp)
    fline_T     *flp;
{
    char_u      *startmarker;
    int         cstart;
    int         cend;
    int         start_lvl = flp->lvl;
    char_u      *s;
    int         n;

    /* cache a few values for speed */
    startmarker = flp->wp->w_p_fmr;
    cstart = *startmarker;
    ++startmarker;
    cend = *foldendmarker;

    /* Default: no start found, next level is same as current level */
    flp->start = 0;
    flp->lvl_next = flp->lvl;

    s = ml_get_buf(flp->wp->w_buffer, flp->lnum + flp->off, FALSE);
    while (*s)
    {
        if (*s == cstart
                  && STRNCMP(s + 1, startmarker, foldstartmarkerlen - 1) == 0)
        {
            /* found startmarker: set flp->lvl */
            s += foldstartmarkerlen;
            if (VIM_ISDIGIT(*s))
            {
                n = atoi((char *)s);
                if (n > 0)
                {
                    flp->lvl = n;
                    flp->lvl_next = n;
                    if (n <= start_lvl)
                        flp->start = 1;
                    else
                        flp->start = n - start_lvl;
                }
            }
            else
            {
                ++flp->lvl;
                ++flp->lvl_next;
                ++flp->start;
            }
        }
        else if (*s == cend
              && STRNCMP(s + 1, foldendmarker + 1, foldendmarkerlen - 1) == 0)
        {
            /* found endmarker: set flp->lvl_next */
            s += foldendmarkerlen;
            if (VIM_ISDIGIT(*s))
            {
                n = atoi((char *)s);
                if (n > 0)
                {
                    flp->lvl = n;
                    flp->lvl_next = n - 1;
                    /* never start a fold with an end marker */
                    if (flp->lvl_next > start_lvl)
                        flp->lvl_next = start_lvl;
                }
            }
            else
                --flp->lvl_next;
        }
        else
            mb_ptr_adv(s);
    }

    /* The level can't go negative, must be missing a start marker. */
    if (flp->lvl_next < 0)
        flp->lvl_next = 0;
}

/* foldlevelSyntax() {{{2 */
/*
 * Low level function to get the foldlevel for the "syntax" method.
 * Doesn't use any caching.
 */
    static void
foldlevelSyntax(flp)
    fline_T     *flp;
{
#ifndef FEAT_SYN_HL
    flp->start = 0;
    flp->lvl = 0;
#else
    linenr_T    lnum = flp->lnum + flp->off;
    int         n;

    /* Use the maximum fold level at the start of this line and the next. */
    flp->lvl = syn_get_foldlevel(flp->wp, lnum);
    flp->start = 0;
    if (lnum < flp->wp->w_buffer->b_ml.ml_line_count)
    {
        n = syn_get_foldlevel(flp->wp, lnum + 1);
        if (n > flp->lvl)
        {
            flp->start = n - flp->lvl;  /* fold(s) start here */
            flp->lvl = n;
        }
    }
#endif
}

/* functions for storing the fold state in a View {{{1 */
/* put_folds() {{{2 */
#if defined(FEAT_SESSION) || defined(PROTO)
static int put_folds_recurse __ARGS((FILE *fd, garray_T *gap, linenr_T off));
static int put_foldopen_recurse __ARGS((FILE *fd, garray_T *gap, linenr_T off));

/*
 * Write commands to "fd" to restore the manual folds in window "wp".
 * Return FAIL if writing fails.
 */
    int
put_folds(fd, wp)
    FILE        *fd;
    win_T       *wp;
{
    if (foldmethodIsManual(wp))
    {
        if (put_line(fd, "silent! normal! zE") == FAIL
                || put_folds_recurse(fd, &wp->w_folds, (linenr_T)0) == FAIL)
            return FAIL;
    }

    /* If some folds are manually opened/closed, need to restore that. */
    if (wp->w_fold_manual)
        return put_foldopen_recurse(fd, &wp->w_folds, (linenr_T)0);

    return OK;
}

/* put_folds_recurse() {{{2 */
/*
 * Write commands to "fd" to recreate manually created folds.
 * Returns FAIL when writing failed.
 */
    static int
put_folds_recurse(fd, gap, off)
    FILE        *fd;
    garray_T    *gap;
    linenr_T    off;
{
    int         i;
    fold_T      *fp;

    fp = (fold_T *)gap->ga_data;
    for (i = 0; i < gap->ga_len; i++)
    {
        /* Do nested folds first, they will be created closed. */
        if (put_folds_recurse(fd, &fp->fd_nested, off + fp->fd_top) == FAIL)
            return FAIL;
        if (fprintf(fd, "%ld,%ldfold", fp->fd_top + off,
                                        fp->fd_top + off + fp->fd_len - 1) < 0
                || put_eol(fd) == FAIL)
            return FAIL;
        ++fp;
    }
    return OK;
}

/* put_foldopen_recurse() {{{2 */
/*
 * Write commands to "fd" to open and close manually opened/closed folds.
 * Returns FAIL when writing failed.
 */
    static int
put_foldopen_recurse(fd, gap, off)
    FILE        *fd;
    garray_T    *gap;
    linenr_T    off;
{
    int         i;
    fold_T      *fp;

    fp = (fold_T *)gap->ga_data;
    for (i = 0; i < gap->ga_len; i++)
    {
        if (fp->fd_flags != FD_LEVEL)
        {
            if (fp->fd_nested.ga_len > 0)
            {
                /* open/close nested folds while this fold is open */
                if (fprintf(fd, "%ld", fp->fd_top + off) < 0
                        || put_eol(fd) == FAIL
                        || put_line(fd, "normal zo") == FAIL)
                    return FAIL;
                if (put_foldopen_recurse(fd, &fp->fd_nested, off + fp->fd_top)
                        == FAIL)
                    return FAIL;
            }
            if (fprintf(fd, "%ld", fp->fd_top + off) < 0
                    || put_eol(fd) == FAIL
                    || fprintf(fd, "normal z%c",
                                    fp->fd_flags == FD_CLOSED ? 'c' : 'o') < 0
                    || put_eol(fd) == FAIL)
                return FAIL;
        }
        ++fp;
    }

    return OK;
}
#endif /* FEAT_SESSION */

/* }}}1 */
#endif /* defined(FEAT_FOLDING) || defined(PROTO) */