--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/liboctave/util/find.h	Tue Jun 17 16:41:11 2014 -0600
@@ -0,0 +1,144 @@
+/*
+
+Copyright (C) 2014 David Spies
+
+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/>.
+
+*/
+#if !defined (octave_find_h)
+#define octave_find_h 1
+
+#include "Array.h"
+
+#include "interp-idx.h"
+#include "min-with-nnz.h"
+#include "nz-iterators.h"
+#include "direction.h"
+
+namespace find
+{
+  // This struct mostly matches the signature of ffind_result (see find.cc)
+  // except without a get_list function.  Internal calls to "find" from
+  // liboctave should call the "find" method which in turn constructs one
+  // of these as a value to be filled.
+  // It should not be used anywhere else
+
+  struct find_result
+  {
+    Array<octave_idx_type> res;
+    template<typename ELT_T>
+    void
+    add (octave_idx_type place, const array_iterator<ELT_T>& iter)
+    {
+      res.xelem (place) = iter.flat_idx ();
+    }
+
+    find_result (void) { }
+    find_result (const dim_vector& nnz) : res (nnz) { }
+  };
+
+  // This is the generic "find" method for all matrix types.  All calls to
+  // "find" get routed here one way or another as this method contains logic
+  // for determining the proper output dimensions and handling forward/reversed,
+  // n_to_find etc.
+  // It would be unwise to try and duplicate this logic elsewhere as it's fairly
+  // nuanced and unintuitive (but Matlab compatible).
+
+  template<typename R, direction dir, typename MT>
+  R
+  find_to_R (dir_handler<dir> dirc, const MT& v, octave_idx_type n_to_find)
+  {
+    typedef typename MT::iter_type iter_t;
+
+    octave_idx_type numres;
+    if (n_to_find == -1)
+      numres = v.nnz ();
+    else
+      numres = min_with_nnz (v, n_to_find);
+
+    const dim_vector& dv = v.dims ();
+    octave_idx_type col_len = dv.elem (0);
+    octave_idx_type cols = dv.numel (1);
+
+    // Fixup return dimensions, for Matlab compatibility.
+    // find (zeros (0,0)) -> zeros (0,0)
+    // find (zeros (1,0)) -> zeros (1,0)
+    // find (zeros (0,1)) -> zeros (0,1)
+    // find (zeros (0,X)) -> zeros (0,1)
+    // find (zeros (1,1)) -> zeros (0,0) !!!! WHY?
+    // find (zeros (0,1,0)) -> zeros (0,0)
+    // find (zeros (0,1,0,1)) -> zeros (0,0) etc
+
+    dim_vector res_dims;
+
+    if ((cols == 1 && col_len == 1 && numres == 0)
+        || (col_len == 0 && cols == 0))
+      res_dims = dim_vector (0, 0);
+    else if (col_len == 1)
+      res_dims = dim_vector (1, numres);
+    else
+      res_dims = dim_vector (numres, 1);
+
+    iter_t iterator (v);
+    R resvec (res_dims);
+    octave_idx_type count = dirc.begin (numres);
+
+    for (iterator.begin (dirc);
+        !iterator.finished (dirc) && !dirc.is_ended (count, numres);
+        iterator.step (dirc), count += dir)
+      {
+        resvec.add (count, iterator);
+      }
+
+    return resvec;
+  }
+
+  // The method call used for internal liboctave calls to find.  It constructs
+  // an find_result and fills that rather than a res_type_of (see "find.cc").
+  // Note that this method only supports full arrays because octave_idx_type
+  // will generally overflow if used to represent the nonzero indices of sparse
+  // arrays. Instead consider using the sparse-iterator class from
+  // nz-iterators.h to avoid this problem
+
+  template<typename ELT_T>
+  Array<octave_idx_type>
+  find (const Array<ELT_T>& v, octave_idx_type n_to_find = -1, direction dir =
+            FORWARD)
+  {
+    find_result resvec;
+
+    switch (dir)
+      {
+      case FORWARD:
+        dir_handler<FORWARD> dirc_forward;
+        resvec = find_to_R<find_result> (dirc_forward, v, n_to_find);
+        break;
+      case BACKWARD:
+        dir_handler<BACKWARD> dirc_back;
+        resvec = find_to_R<find_result> (dirc_back, v, n_to_find);
+        break;
+      default:
+        liboctave_fatal(
+                "find: unknown direction: %d; must be FORWARD or BACKWARD",
+                dir);
+      }
+
+    return resvec.res;
+  }
+}
+
+#endif