1 files changed, 77 insertions, 0 deletions
diff --git a/gnuradio-runtime/python/gnuradio/gru/seq_with_cursor.py b/gnuradio-runtime/python/gnuradio/gru/seq_with_cursor.py
new file mode 100644
index 0000000000..def3299b69
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+++ b/gnuradio-runtime/python/gnuradio/gru/seq_with_cursor.py
@@ -0,0 +1,77 @@
+#
+# Copyright 2003,2004 Free Software Foundation, Inc.
+#
+# This file is part of GNU Radio
+#
+# GNU Radio 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, or (at your option)
+# any later version.
+#
+# GNU Radio 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 GNU Radio; see the file COPYING.  If not, write to
+# the Free Software Foundation, Inc., 51 Franklin Street,
+# Boston, MA 02110-1301, USA.
+#
+
+# misc utilities
+
+import types
+import exceptions
+
+class seq_with_cursor (object):
+    __slots__ = [ 'items', 'index' ]
+
+    def __init__ (self, items, initial_index = None, initial_value = None):
+        assert len (items) > 0, "seq_with_cursor: len (items) == 0"
+        self.items = items
+        self.set_index (initial_index)
+        if initial_value is not None:
+            self.set_index_by_value(initial_value)
+
+    def set_index (self, initial_index):
+        if initial_index is None:
+            self.index = len (self.items) / 2
+        elif initial_index >= 0 and initial_index < len (self.items):
+            self.index = initial_index
+        else:
+            raise exceptions.ValueError
+
+    def set_index_by_value(self, v):
+        """
+        Set index to the smallest value such that items[index] >= v.
+        If there is no such item, set index to the maximum value.
+        """
+        self.set_index(0)              # side effect!
+        cv = self.current()
+        more = True
+        while cv < v and more:
+            cv, more = self.next()      # side effect!
+
+    def next (self):
+        new_index = self.index + 1
+        if new_index < len (self.items):
+            self.index = new_index
+            return self.items[new_index], True
+        else:
+            return self.items[self.index], False
+
+    def prev (self):
+        new_index = self.index - 1
+        if new_index >= 0:
+            self.index = new_index
+            return self.items[new_index], True
+        else:
+            return self.items[self.index], False
+
+    def current (self):
+        return self.items[self.index]
+
+    def get_seq (self):
+        return self.items[:]            # copy of items
+