U8 *Tabs2Spaces(U8 *src)
{//MAlloc str with tabs to spaces.
    I64 ch, i, j, l = StrLen(src) << 1 + 2, col = 0;
    U8 *dst = MAlloc(l), *tmp;

    while (ch = *src++)
    {
        if (ch == '\t')
        {
            j = (col + 8) & ~7;
            for (i = col; i < j; i++)
            {
                dst[i] = CH_SPACE;
                if (i >= l - 2)
                {
                    tmp = MAlloc(l << 1);
                    MemCopy(tmp, dst, i + 1);
                    Free(dst);
                    l <<= 1;
                    dst = tmp;
                }
            }
            col = j;
        }
        else
        {
            dst[col] = ch;
            if (col >= l - 2)
            {
                tmp = MAlloc(l << 1);
                MemCopy(tmp, dst, col + 1);
                Free(dst);
                l <<= 1;
                dst = tmp;
            }
            col++;
        }
    }
    dst[col] = 0;

    return dst;
}

U8 *ScaleIndent(U8 *src, F64 indent_scale_factor)
{//MAlloced str.    8*0.25-->2 or 8*2.0-->16
    I64 ch, i, col = 0;
    U8 *dst, *dst2;

    while (ch = *src++)
    {
        if (ch == '\t')
            col = (col + 8) & -0x8;
        else if (ch == CH_SPACE)
            col++;
        else
            break;
    }
    src--;
    col = Round(indent_scale_factor * col);
    dst = dst2 = MAlloc(StrLen(src) + col / 8 + col & 7 + 1);
    for (i = col / 8; i > 0; i--)
        *dst2++ = '\t';
    for (i = col & 7; i > 0; i--)
        *dst2++ = CH_SPACE;
    StrCopy(dst2, src);

    return dst;
}

U8 *MStrUtil(U8 *src, I64 flags, F64 indent_scale_factor=0)
{//MAlloc StrUtil().
    U8 *dst = StrNew(src), *dst2, *tmp;

    StrUtil(dst, flags);
    if (flags & SUF_T2S)
    {
        tmp = Tabs2Spaces(dst);
        Free(dst);
        dst = tmp;
    }
    if (flags & SUF_SCALE_INDENT)
        dst2 = ScaleIndent(dst, indent_scale_factor);
    else
        dst2 = StrNew(dst); //Shorten to just right size.
    Free(dst);

    return dst2;
}

U0 GetOutOfDollar()
{//If a $ has been printed, print another $ to exit mode.
    CDoc *doc;

    if (IsRaw)
    {
        if (text.raw_flags & RAWF_IN_DOLLAR)
            '$';
    }
    else
    {
        if (fp_doc_put && (doc = (*fp_doc_put)(Fs)) && doc->flags & DOCF_IN_DOLLAR)
            '$';
    }
}

Bool YorN()
{//Wait for user to answer Y or N.
    I64 ch;

    "(y or n)? ";
    while (TRUE)
    {
        ch = ToUpper(CharGet(, FALSE));
        if (ch == 'Y')
        {
            "$PT$YES$FG$\n";
            return TRUE;
        }
        else if (ch == 'N')
        {
            "$PT$NO$FG$\n";
            return FALSE;
        }
    }
}

I64 PressAKey()
{//Print "Press a key" and wait for non-zero ASCII key.
    "$BK,1$PRESS A KEY$BK,0$\n";
    return CharGet(, FALSE);
}

Bool AreYouSure()
{//Print "Are you sure" and waits for Y or N.
    "ARE YOU SURE ";
    return YorN;
}

U0 Help()
{//Debug help or master help index file.
    if (IsDebugMode)
        DebugHelp;
    else
        PopUp("Type(\"::/Doc/HelpIndex.DD\");DocTop;View;");
}

U0 FlagsScan(U8 *_dst_flags, U8 *list, U8 *src)
{/*More than 64 flags. Flags passed by ref.

Examples:
FlagsScan(&fuf_flags,Define("ST_FILE_UTIL_FLAGS"),fu_flags);

I64 flags=0;
FlagsScan(&flags,"R\0L\0Dump\0Scan\0","+Dump-R"); //Sets Bit#2, Clears Bit#0.
*/
    I64 i;
    U8 *buf, *ptr;

    if (src)
    {
        buf = MAlloc(StrLen(src) + 1);
        while (*src)
        {
            while (*src && *src != '+' && *src != '-')
                src++;
            if (*src == '+')
            {
                src++;
                if (*src)
                {
                    ptr = buf;
                    while (*src && *src != '+' && *src != '-' && *src != CH_SPACE)
                        *ptr++ = *src++;
                    *ptr = 0;
                    i = ListMatch(buf, list);
                    if (i >= 0)
                        LBts(_dst_flags, i);
                    else
                    {
                        Free(buf);
                        throw('ScanFlag');
                    }
                }
            }
            else if (*src == '-')
            {
                src++;
                if (*src)
                {
                    ptr = buf;
                    while (*src && *src != '+' && *src != '-' && *src != CH_SPACE)
                        *ptr++ = *src++;
                    *ptr = 0;
                    i = ListMatch(buf, list);
                    if (i >= 0)
                        LBtr(_dst_flags, i);
                    else
                    {
                        Free(buf);
                        throw('ScanFlag');
                    }
                }
            }
        }
        Free(buf);
    }
}

U8 *FlagsStrPrint(U8 *dst, U8 *list, I64 flags, Bool print_all=FALSE, I64 print_all_length=0)
{//Only 64 flags. Flags passed by value. print_all will print false flags using `-`.
//Specify print_all_length (list length) if print_all is true.
    I64 i = 0;

    *dst = 0;
    if (!print_all_length)
        print_all_length =  64;
    while (i < print_all_length)
    {
        if (Bt(&flags, i))
            CatPrint(dst, "+%z", i, list);
        else if (print_all)
            CatPrint(dst, "-%z", i, list);
        i++;
    }

    return dst;
}