## Copyright (C) 2000-2016 Daniel Calvelo
##
## 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
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {} {} base2dec (@var{s}, @var{base})
## Convert @var{s} from a string of digits in base @var{base} to a decimal
## integer (base 10).
##
## @example
## @group
## base2dec ("11120", 3)
##    @result{} 123
## @end group
## @end example
##
## If @var{s} is a string matrix, return a column vector with one value per
## row of @var{s}.  If a row contains invalid symbols then the corresponding
## value will be NaN@.
##
## If @var{s} is a cell array of strings, return a column vector with one
## value per cell element in @var{s}.
##
## If @var{base} is a string, the characters of @var{base} are used as the
## symbols for the digits of @var{s}.  Space (' ') may not be used as a symbol.
##
## @example
## @group
## base2dec ("yyyzx", "xyz")
##    @result{} 123
## @end group
## @end example
## @seealso{dec2base, bin2dec, hex2dec}
## @end deftypefn

## Author: Daniel Calvelo <dcalvelo@yahoo.com>
## Adapted-by: Paul Kienzle <pkienzle@kienzle.powernet.co.uk>

function out = base2dec (s, base)

  if (nargin != 2)
    print_usage ();
  endif

  if (iscellstr (s))
    s = char (s);
  elseif (! ischar (s))
    error ("base2dec: S must be a string or cellstring");
  endif

  symbols = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
  if (ischar (base))
    symbols = base;
    base = length (symbols);
    if (length (unique (symbols)) != base)
      error ("base2dec: symbols representing digits must be unique");
    endif
    if (any (isspace (symbols)))
      error ("base2dec: whitespace characters are not valid symbols");
    endif
  elseif (! isscalar (base))
    error ("base2dec: cannot convert from several bases at once");
  elseif (base < 2 || base > length (symbols))
    error ("base2dec: BASE must be between 2 and 36, or a string of symbols");
  else
    s = toupper (s);
  endif

  ## Right justify the values and squeeze out any spaces.
  ## This looks complicated, but indexing solution is very fast
  ## compared to alternatives which use cellstr or cellfun or looping.
  [nr, nc] = size (s);
  if (nc > 1)   # Bug #35621
    s = s.';
    nonbl = s != " ";
    num_nonbl = sum (nonbl);
    nc = max (num_nonbl);
    num_blank = nc - num_nonbl;
    R = repmat ([1 2; 0 0], 1, nr);
    R(2, 1:2:2*nr) = num_blank;
    R(2, 2:2:2*nr) = num_nonbl;
    idx = repelems ([false, true], R);
    idx = reshape (idx, nc, nr);

    ## Create a blank matrix and position the nonblank characters.
    s2 = repmat (" ", nc, nr);
    s2(idx) = s(nonbl);
    s = s2.';
  endif

  ## Lookup value of symbols in symbol table, with invalid symbols
  ## evaluating to NaN and space evaluating to 0.
  table = NaN (1, 256);
  table(toascii (symbols(1:base))) = 0 : base-1;
  table(toascii (" ")) = 0;
  s = reshape (table(toascii (s)), size (s));

  ## Multiply the resulting digits by the appropriate power
  ## and sum the rows.
  out = s * (base .^ (columns(s)-1 : -1 : 0)');

endfunction


%!assert (base2dec ("11120", 3), 123)
%!assert (base2dec ("yyyzx", "xyz"), 123)
%!assert (base2dec ("-1", 2), NaN)
%!assert (base2dec ({"A1", "1A"}, 16), [161; 26])

%!assert <35621> (base2dec (["0"; "1"], 2), [0; 1])

## Test input validation
%!error base2dec ()
%!error base2dec ("11120")
%!error base2dec ("11120", 3, 4)
%!error base2dec ("11120", "1231")
%!error base2dec ("11120", "12 3")
%!error base2dec ("11120", ones (2))
%!error base2dec ("11120", 37)

