OpenEuphoria

Re: String types

• Posted by jbrown105 at speedymail.org Nov 08, 2002
• 403 views

Yeah, this is it. Personally, I'd prefer the C char arrary lib, but thats
just
me.

On  0, Juergen Luethje <jluethje at gmx.de> wrote:
> 
> jbrown wrote:
> 
> <snip>
> > Didnt some one find a way to "compress" a sequence, so that each
> > element would have space to hold 4 characters? (Hence 100mb would take
> > 25 or so mil elements, and actually BE only 100 mb in memory, then you
> > could use the same scheme and access like 50 characters at a time,
> > hence saving on memory.)
> >
> > That said (i.e. that workarounds do exist) its still a bit of a kludge.
> > It'd be nice if Euphoria supported such things directly. <snip>
> 
> Do you mean something like this?
> 
> --====================================================================--
> 
> -- pack_str.e, v1.0
> 
> type string (object x)
>    object t
> 
>    if atom(x) then return 0 end if
> 
>    for i = 1 to length(x) do
>       t = x[i]
>       if not integer(t) or t < 0 or t > #FF then
>          return 0
>       end if
>    end for
>    return 1
> end type
> 
> 
> function ceil (object x)
>    -- the opposite of floor()
>    return -floor(-x)
> end function
> 
> 
> function pack4 (string s)
>    -- length(s) must be <= 4
>    atom ret
> 
>    ret = 0
>    for i = length(s) to 1 by -1 do
>       ret = ret*#100 + s[i]
>    end for
>    return ret
> end function
> 
> 
> function unpack4 (atom d)
>    sequence ret
>    integer i
> 
>    ret = {0,0,0,0}
>    i = 1
>    while d do
>       ret[i] = remainder(d, #100)
>       d = floor(d/#100)
>       i += 1
>    end while
>    return ret
> end function
> 
> ------------------------------------------------------------------------
> 
> global function pack_string (string u)
>    sequence ret
>    integer n, i
> 
>    n = ceil(length(u)/4) + 1
>    ret = repeat(0, n)
>    ret[1] = length(u)    -- If length() is not stored, there will be
>    i = 1                 -- problems with trailing zeros.
>    for k = 2 to n-1 do
>       ret[k] = pack4(u[i..i+3])
>       i += 4
>    end for
>    ret[n] = pack4(u[i..length(u)])
>    return ret
> end function
> 
> 
> global function unpack_string (sequence p)
>    sequence ret
>    integer i
> 
>    ret = repeat(0, length(p)*4)
>    i = 1
>    for k = 2 to length(p) do
>       ret[i..i+3] = unpack4(p[k])
>       i += 4
>    end for
>    return ret[1..p[1]]
> end function
> 
> ------------------------------------------------------------------------
> 
> include misc.e
<snip>

> 
> 
> 

--