% Copyright (C) 2001-2023 Artifex Software, Inc.
% All Rights Reserved.
%
% This software is provided AS-IS with no warranty, either express or
% implied.
%
% This software is distributed under license and may not be copied,
% modified or distributed except as expressly authorized under the terms
% of the license contained in the file LICENSE in this distribution.
%
% Refer to licensing information at http://www.artifex.com or contact
% Artifex Software, Inc.,  39 Mesa Street, Suite 108A, San Francisco,
% CA 94129, USA, for further information.
%

% Implementation of ReusableStreamDecode filter.
% This file must be loaded after gs_lev2.ps and gs_res.ps.

level2dict begin

% ------ ReusableStreamDecode filter ------ %

/.reusablestreamdecode {	% <source> <dict> .reusablestreamdecode <file>
                                % <source> .reusablestreamdecode <file>
                % Collect the filter parameters.
  dup type /dicttype eq { 2 copy } { dup 0 dict } ifelse
  dup .rsdparams
                % Construct the filter pipeline.
                % The very first filter should use the value of CloseSource
                % from the RSD dictionary; all the others should have
                % CloseSource = true.
                % Stack: source dict filters parms
  2 index /CloseSource .knownget not { //false } if 5 -1 roll
                % Stack: dict filters parms CloseSource source
  0 1 5 index length 1 sub {
    4 index 1 index get
                % Stack: dict filters parms CloseSource source index filtname
    4 index //null eq {
      0 dict
    } {
      4 index 2 index get dup //null eq { pop 0 dict} if
    } ifelse
    3 -1 roll pop exch filter
    exch pop //true exch		% set CloseSource for further filters
  } for
                % If AsyncRead is true, try to create the filter directly.
                % Stack: dict filters parms CloseSource source
  4 index /AsyncRead .knownget not { //false } if {
    1 index { .reusablestream } //.internalstopped exec
  } {
    //null //true
  } ifelse {
    pop
                % No luck.  Read the entire contents of the stream now.
    dup type /filetype ne {
                % Make a stream from a procedure or string data source.
      0 () .subfiledecode
    } if
                % We must allocate the string in the same VM space as its
                % source, since the reusable stream must be allocated there.

    .currentglobal 1 index gcheck .setglobal exch
    currentpacking //false setpacking exch
    2 dict begin /filelen 0 def		% scratch dict for filelen and pos (below).
                % Stack: dict filters parms CloseSource oldglobal oldpacking file
    [ exch {
        dup 40000 string readstring
        /filelen 2 index length filelen add def	% accumulate filelen
        not { exit } if exch
      } loop
      exch pop
    ]
    { filelen string } stopped {	% try allocating a single string
      pop	% couldn't make a string - discard filelen value
    } {
      % transfer the array-of-strings to the single string.
      % stack: ... [() ...] string
      /pos 0 def exch {
        1 index exch pos exch putinterval /pos pos 40000 add def
      } forall
    } ifelse
    % top of stack is either array of strings or one string == stream_data
    end	% done with scratch dict
                        % Stack: dict filters parms CloseSource oldglobal oldpacking stream_data
    3 1 roll setpacking setglobal
                        % Stack: dict filters parms CloseSource stream_data
    1 index .reusablestream
  } if
                % We created the stream successfully: clean up.
  4 { exch pop } repeat
  1 index type /dicttype eq { exch pop } if exch pop
} odef

filterdict /ReusableStreamDecode /.reusablestreamdecode load put

end			% level2dict
