Added special-case logical-indexing function * logical-index.h (New file) : Logical-indexing function. May be called on octave_value types via call_bool_index * nz-iterators.h : Add base-class nz_iterator for iterator types. Array has template bool for whether to internally store row-col or compute on the fly Add skip_ahead method which skips forward to the next nonzero after its argument Add flat_index for computing octave_idx_type index of current position (with assertion failure in the case of overflow) Move is_zero to separate file * ov-base-diag.cc, ov-base-mat.cc, ov-base-sparse.cc, ov-perm.cc (do_index_op): Add call to call_bool_index in logical-index.h * Array.h : Move forward-declaration for array_iterator to separate header file * dim-vector.cc (dim_max): Refers to idx-bounds.h (max_idx) * array-iter-decl.h (New file): Header file for forward declaration of array-iterator * direction.h : Add constants fdirc and bdirc to avoid having to reconstruct them * dv-utils.h, dv-utils.cc (New files) : Utility functions for querying and constructing dim-vectors * idx-bounds.h (New file) : Utility constants and functions for determining whether things will overflow the maximum allowed bounds * interp-idx.h (New function : to_flat_idx) : Converts row-col pair to linear index of octave_idx_type * is-zero.h (New file) : Function for determining whether an element is zero * logical-index.tst : Add tests for correct return-value dimensions and large sparse matrix behavior

#include <octave/oct.h>
#include <octave/ov-struct.h>

DEFUN_DLD (structdemo, args, , "Struct Demo")
{
  octave_value retval;
  int nargin = args.length ();

  if (args.length () == 2)
    {
      octave_scalar_map arg0 = args(0).scalar_map_value ();
      //octave_map arg0 = args(0).map_value ();

      if (! error_state)
        {
          std::string arg1 = args(1).string_value ();

          if (! error_state)
            {
              octave_value tmp = arg0.contents (arg1);
              //octave_value tmp = arg0.contents (arg1)(0);

              if (tmp.is_defined ())
                {
                  octave_scalar_map st;

                  st.assign ("selected", tmp);

                  retval = octave_value (st);
                }
              else
                error ("structdemo: struct does not have a field named '%s'\n",
                       arg1.c_str ());
            }
          else
            error ("structdemo: ARG2 must be a character string");
        }
      else
        error ("structdemo: ARG1 must be a struct");
    }
  else
    print_usage ();

  return retval;
}