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## -*- texinfo -*-
## @deftypefn  {} {@var{idx} =} strmatch (@var{s}, @var{A})
## @deftypefnx {} {@var{idx} =} strmatch (@var{s}, @var{A}, "exact")
##
## This function is obsolete.  @strong{Use an alternative} such as
## @code{strncmp} or @code{strcmp} instead.
##
## Return indices of entries of @var{A} which begin with the string @var{s}.
##
## The second argument @var{A} must be a string, character matrix, or a cell
## array of strings.
##
## If the third argument @qcode{"exact"} is not given, then @var{s} only
## needs to match @var{A} up to the length of @var{s}.  Trailing spaces and
## nulls in @var{s} and @var{A} are ignored when matching.
##
## For example:
##
## @example
## @group
## strmatch ("apple", "apple juice")
##      @result{} 1
##
## strmatch ("apple", ["apple  "; "apple juice"; "an apple"])
##      @result{} [1; 2]
##
## strmatch ("apple", ["apple  "; "apple juice"; "an apple"], "exact")
##      @result{} [1]
## @end group
## @end example
##
## @strong{Caution:} @code{strmatch} is obsolete (and can produce incorrect
## results in @sc{matlab} when used with cell arrays of strings.  Use
## @code{strncmp} (normal case) or @code{strcmp} (@qcode{"exact"} case) in all
## new code.  Other replacement possibilities, depending on application,
## include @code{regexp} or @code{validatestring}.
## @seealso{strncmp, strcmp, regexp, strfind, validatestring}
## @end deftypefn

function idx = strmatch (s, A, exact)

  persistent warned = false;
  if (! warned)
    warned = true;
    warning ("Octave:legacy-function",
             "strmatch is obsolete; use strncmp or strcmp instead\n");
  endif

  if (nargin < 2)
    print_usage ();
  endif

  if (iscellstr (s))
    if (numel (s) > 1)
      error ("strmatch: a cell array S must contain only one string");
    endif
    s = char (s);
  elseif (! ischar (s) || (! isempty (s) && ! isrow (s)))
    error ("strmatch: S must be a string");
  elseif (! (ischar (A) || iscellstr (A)))
    error ("strmatch: A must be a string or cell array of strings");
  endif

  ## Trim blanks and nulls from search string
  if (any (s != " " & s != "\0"))
    s = regexprep (s, "[ \\0]+$", '');
  endif
  len = length (s);

  exact = nargin == 3 && ischar (exact) && strcmp (exact, "exact");

  if (ischar (A))
    [nr, nc] = size (A);
    if (len > nc)
      idx = [];
    else
      match = all (bsxfun (@eq, A(:,1:len), s), 2);
      if (exact)
        AA = A(:,len+1:nc);
        match &= all (AA == " " | AA == "\0", 2);
      endif
      idx = find (match);
    endif
  else
    if (len > 0)
      idx = find (strncmp (s, A, len));
    else
      idx = find (strcmp (s, A));
    endif
    if (exact)
      ## We can't just use strcmp, because we need to ignore spaces at end.
      B = regexprep (A(idx), "[ \\0]+$", '');
      idx = idx(strcmp (s, B));
    endif
  endif

  ## Return exactly sized and shaped values for Matlab compatibility.
  if (isempty (idx))
    idx = [];  # always return 0x0 empty matrix for non-match.
  else
    idx = idx(:);  # always return column vector.
  endif

endfunction


## First test is necessary to provoke 1-time legacy warning
%!test
%! warning ("off", "Octave:legacy-function", "local");
%! strmatch ("", "");

%!assert (strmatch ("a", {"aaa", "bab", "bbb"}), 1)
%!assert (strmatch ("apple", "apple juice"), 1)
%!assert (strmatch ("apple", ["apple pie"; "apple juice"; "an apple"]), [1; 2])
%!assert (strmatch ("apple", {"apple pie"; "apple juice"; "tomato"}), [1; 2])
%!assert (strmatch ("apple pie", "apple"), [])
%!assert (strmatch ("a ", "a"), 1)
%!assert (strmatch ("a", "a \0", "exact"), 1)
%!assert (strmatch ("a b", {"a b", "a c", "c d"}), 1)
%!assert (strmatch ("", {"", "foo", "bar", ""}), [1; 4])
%!assert (strmatch ('', {'', '% comment', 'var a = 5', ''}, "exact"), [1;4])

## Weird Matlab corner cases
%!test <*49601>
%! assert (strmatch (" ", " "), 1);
%! assert (strmatch (" ", "   "), 1);
%! assert (strmatch ("  ", " "), []);
%! assert (strmatch ("  ", "  "), 1);
%!test <*54432>
%! assert (strmatch ({"a"}, {"aaa", "bab", "bbb"}), 1);
%! assert (isempty (strmatch ({}, {"aaa", "bab"})));
%!test <*59917>
%! a = { "dfr", "tgh", "rere", "rere" };
%! b = strmatch ("rere", a, "exact");
%! assert (b, [3; 4]);

## Test input validation
%!error <Invalid call to strmatch> strmatch ()
%!error <Invalid call to strmatch> strmatch ("a")
%!error <called with too many inputs> strmatch ("a", "aaa", "exact", 1)
%!error <S must contain only one string> strmatch ({"a", "b"}, "aaa")
%!error <S must be a string> strmatch (1, "aaa")
%!error <S must be a string> strmatch (char ("a", "bb"), "aaa")
%!error <A must be a string> strmatch ("a", 1)
%!error <A must be a string> strmatch ("a", {"hello", [1]})