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########################################################################
##
## Copyright (C) 2004-2024 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/>.
##
########################################################################
##
## Original version by Paul Kienzle distributed as free software in the
## public domain.
## -*- texinfo -*-
## @deftypefn {} {@var{namestr} =} inputname (@var{n})
## @deftypefnx {} {@var{namestr} =} inputname (@var{n}, @var{ids_only})
## Return the name of the @var{n}-th argument to the calling function.
##
## If the argument is not a simple variable name, return an empty string.
## Examples which will return @qcode{""} are numbers (@code{5.1}),
## expressions (@code{@var{y}/2}), and cell or structure indexing
## (@code{@var{c}@{1@}} or @code{@var{s}.@var{field}}).
##
## @code{inputname} is only useful within a function. When used at the command
## line or within a script it always returns an empty string.
##
## By default, return an empty string if the @var{n}-th argument is not a valid
## variable name. If the optional argument @var{ids_only} is false, return the
## text of the argument even if it is not a valid variable name. This is an
## Octave extension that allows the programmer to view exactly how the function
## was invoked even when the inputs are complex expressions.
## @seealso{nargin, narginchk}
## @end deftypefn
## FIXME: Actually, it probably *isn't* worth fixing, but there are small
## differences between Octave and Matlab.
##
## 1) When called from the top-level or a script, Matlab throws an error
##
## inputname (1) % at command prompt
## % Octave returns "", Matlab throws an error
##
## 2) cell or struct indexing causes all further names to be returned as ""
##
## c = {'a', 'b'}
## y = 1; z = 2;
## fcn (c, y, z)
## % inputname() would return 'c', 'y', 'z' for the inputs.
## fcn (c{1}, y, z)
## % inputname() would return '', '', '' for the inputs.
##
## 3) If inputname is not called from a function, Matlab walks up the stack
## until it finds some valid code and then works from there. This could
## be relevant for mex files or anonymous functions.
##
## f = @(x) inputname (x);
## a = 1:4;
## arrayfun (fn, a, 'uniformoutput', false)
## % output is {'fn', 'a', '', ''}
function namestr = inputname (n, ids_only = true)
if (nargin < 1)
print_usage ();
endif
if (! isscalar (n) || ! isindex (n))
error ("inputname: N must be a scalar index");
endif
try
namestr = evalin ("caller", sprintf ("__varval__ ('.argn.'){%d}", n));
catch
namestr = "";
return;
end_try_catch
## For compatibility with Matlab, return empty string if argument name is
## not a valid identifier.
if (ids_only && ! isvarname (namestr))
namestr = "";
elseif (ids_only)
## More complicated checking is required to verify name (bug #59103).
## NAME may be text, like "Inf", which is an acceptable variable name
## that passes isvarname(), but that does not mean it is an actual
## variable name, rather than a function or IEEE number.
try
v = evalin ("caller",
sprintf ("evalin ('caller', '__varval__ (\"%s\")')", namestr));
catch
namestr = "";
end_try_catch
endif
endfunction
%!function name = __iname1__ (arg1, arg2, arg3)
%! name = inputname (1);
%!endfunction
%!function name = __iname1_ID__ (arg1, arg2, arg3)
%! name = inputname (1, false);
%!endfunction
%!function name = __iname2__ (arg1, arg2, arg3)
%! name = inputname (2);
%!endfunction
%!function names = __iname3__ (arg1, arg2, arg3)
%! names = cell (1, 3);
%! for i = 1:3
%! names{i} = inputname (i);
%! endfor
%!endfunction
%!test
%! assert (__iname1__ ('xvar'), "");
%! xvar = 1;
%! assert (__iname1__ (xvar), "xvar");
%!test
%! xvar = 1; yvar = 2;
%! assert (__iname2__ (xvar), "");
%! assert (__iname2__ (xvar, yvar), "yvar");
%!test
%! xvar = 1; yvar = 2;
%! assert (__iname3__ (xvar), {"xvar", "", ""});
%! assert (__iname3__ (xvar, yvar), {"xvar", "yvar", ""});
%! assert (__iname3__ (xvar, 3, yvar), {"xvar", "", "yvar"});
## Test numbers, expressions, indexing operations
%!test
%! assert (__iname1__ (1.0), "");
%! x = 1;
%! assert (__iname1__ (x / 2), "");
%! assert (__iname1__ (Inf), "");
%!test
%! assert (__iname1_ID__ (1.0), "1.0");
%! x = 1;
%! assert (__iname1_ID__ (x / 2), "x / 2");
%! assert (__iname1_ID__ (Inf), "Inf");
%!error <Invalid call> inputname ()
%!error <N must be a scalar> inputname (ones (2,2))
%!error <N must be a scalar index> inputname (-1)
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