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########################################################################
##
## Copyright (C) 2009-2025 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## This file is part of Octave.
##
## Octave is free software: you can redistribute it and/or modify it
## under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## Octave is distributed in the hope that it will be useful, but
## WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with Octave; see the file COPYING. If not, see
## <https://www.gnu.org/licenses/>.
##
########################################################################
## -*- texinfo -*-
## @deftypefn {} {@var{value} =} __gnuplot_get_var__ (@var{h}, @var{gp_var_name}, @var{fmt})
## Undocumented internal function.
## @end deftypefn
function gp_var_value = __gnuplot_get_var__ (h, gp_var_name, fmt = "")
if (numel (h) == 1 && isfigure (h))
if (isempty (get (h, "__plot_stream__")))
ostream = __gnuplot_open_stream__ (2, h);
else
ostream = get (h, "__plot_stream__");
endif
else
ostream = h;
endif
if (numel (ostream) < 1)
error ("__gnuplot_get_var__: stream to gnuplot not open");
elseif (ispc ())
if (numel (ostream) == 1)
error ("__gnuplot_get_var__: Need mkfifo that is not implemented under Windows");
endif
use_mkfifo = false;
istream = ostream(2);
ostream = ostream(1);
else
use_mkfifo = true;
ostream = ostream(1);
endif
if (use_mkfifo)
gpin_name = tempname ();
[err, msg] = mkfifo (gpin_name, 600);
if (err)
error ("__gnuplot_get_var__: Can not make FIFO (%s)", msg);
endif
endif
gp_var_name = strtrim (gp_var_name);
n = min (strfind (gp_var_name, " "), strfind (gp_var_name, ",")) - 1;
if (isempty (n))
n = numel (gp_var_name);
endif
unwind_protect
## Notes: Variables may be undefined if user closes gnuplot by "q"
## or Alt-F4. Further, this abrupt close also requires the leading
## "\n" on the next line.
if (use_mkfifo)
fprintf (ostream, ["\n" 'set print "%s";' "\n"], gpin_name);
fflush (ostream);
[gpin, err] = fopen (gpin_name, "r");
if (err)
## Try a second time, and then give an error.
[gpin, err] = fopen (gpin_name, "r");
endif
if (err)
error ("__gnuplot_get_var__: can not open FIFO");
endif
gp_cmd = sprintf (["\n" 'if (exists("%s")) print %s; else print NaN' "\n"],
gp_var_name(1:n), gp_var_name);
fputs (ostream, gp_cmd);
## Close output file, to force it to be flushed
fputs (ostream, "set print;\n");
fflush (ostream);
## Now read from fifo.
reading = true;
str = {};
while (reading)
str{end+1} = fgets (gpin);
if (isnumeric (str{end}) && (str{end} == -1))
reading = false;
str = str(1:(end-1));
endif
endwhile
str = strcat (str{:});
fclose (gpin);
else
## Direct gnuplot to print to <STDOUT>
fprintf (ostream, ['set print "-";' "\n"]);
fflush (ostream);
gp_cmd = sprintf (["\n" 'if (exists("%s")) print "OCTAVE: ", %s, ' ...
'" :END_OCTAVE"; else print NaN' "\n"],
gp_var_name(1:n), gp_var_name);
fputs (ostream, gp_cmd);
fflush (ostream);
## Direct gnuplot to print to <STDERR>
fputs (ostream, "set print;\n");
fflush (ostream);
str = "";
t_start = tic ();
while (toc (t_start) < 10)
str = [str, fread(istream, "*char")'];
if (! isempty (str))
re_str = regexp (str, "OCTAVE: (.*) :END_OCTAVE", "tokens");
if (! isempty (re_str))
str = re_str{end}{1};
break;
endif
endif
fclear (istream);
endwhile
endif
## Strip out EOLs and the continuation character "|"
str(str=="\n" | str=="\r") = "";
n_continue = strfind (str, " \\ ");
if (! isempty (n_continue))
str(n_continue+1) = "";
endif
if (isempty (fmt))
gp_var_value = strtrim (str);
else
gp_var_value = sscanf (str, fmt);
endif
unwind_protect_cleanup
if (use_mkfifo)
unlink (gpin_name);
endif
end_unwind_protect
endfunction
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