# HG changeset patch
# User Jaroslav Hajek <address@hidden>
# Date 1238826656 -7200
# Node ID 5d6d0bc9aeb4fdbfa6d360e060383135bdfa8ecd
# Parent  b7210faa3ed0d9b52d730309c88c46668d1cb836
optimize simple stack operations on arrays

diff --git a/liboctave/Array.cc b/liboctave/Array.cc
--- a/liboctave/Array.cc
+++ b/liboctave/Array.cc
@@ -53,14 +53,6 @@
     {
       --rep->count;
       rep = new ArrayRep (slice_data, slice_len, true);
-      slice_data = rep->data;
-    }
-  else if (slice_len != rep->len)
-    {
-      // Possibly economize here.
-      ArrayRep *new_rep = new ArrayRep (slice_data, slice_len, true);
-      delete rep;
-      rep = new_rep;
       slice_data = rep->data;
     }
 }
@@ -1072,7 +1064,36 @@
       else
         {
           octave_idx_type nx = numel ();
-          if (n != nx)
+          if (n == nx - 1 && n > 0)
+            {
+              // Stack "pop" operation.
+              if (rep->count == 1)
+                slice_data[slice_len-1] = T ();
+              slice_len--;
+              dimensions = dv;
+            }
+          else if (n == nx + 1 && nx > 0)
+            {
+              // Stack "push" operation.
+              if (rep->count == 1 && slice_data + slice_len < rep->data + rep->len)
+                {
+                  slice_data[slice_len++] = rfv;
+                  dimensions = dv;
+                }
+              else
+                {
+                  static const octave_idx_type max_stack_chunk = 1024;
+                  octave_idx_type nn = n + std::min (nx, max_stack_chunk);
+                  Array<T> tmp (Array<T> (nn), dv, 0, n);
+                  T *dest = tmp.fortran_vec ();
+
+                  std::copy (data (), data () + nx, dest);
+                  dest[nx] = rfv;
+
+                  *this = tmp;
+                }
+            }
+          else if (n != nx)
             {
               Array<T> tmp = Array<T> (dv);
               T *dest = tmp.fortran_vec ();
@@ -1489,9 +1510,13 @@
   else if (i.length (n) != 0)
     {
       octave_idx_type l, u;
-
       bool col_vec = ndims () == 2 && columns () == 1 && rows () != 1;
-      if (i.is_cont_range (n, l, u))
+      if (i.is_scalar () && i(0) == n-1)
+        {
+          // Stack "pop" operation.
+          resize (n-1);
+        }
+      else if (i.is_cont_range (n, l, u))
         {
           // Special case deleting a contiguous range.
           octave_idx_type m = n + l - u;
diff --git a/liboctave/ChangeLog b/liboctave/ChangeLog
--- a/liboctave/ChangeLog
+++ b/liboctave/ChangeLog
@@ -0,0 +1,8 @@
+2009-04-04  Jaroslav Hajek  <address@hidden>
+
+	* Array.cc (Array<T>::make_unique): Don't economize when unique.
+	(Array<T>::resize_fill (octave_idx_type, const T&)): Optimize push &
+	pop operations.
+	(Array<T>::delete_elements (const idx_vector&)): Do pop operation
+	using resize.
+