1 files changed, 77 insertions, 0 deletions
diff --git a/bestflags/flags_util.py b/bestflags/flags_util.py
new file mode 100644
index 00000000..01cc8d66
--- /dev/null
+++ b/bestflags/flags_util.py
@@ -0,0 +1,77 @@
+# Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Utility functions to explore the neighbor flags.
+
+Part of the Chrome build flags optimization.
+"""
+
+__author__ = 'yuhenglong@google.com (Yuheng Long)'
+
+
+import flags
+from flags import Flag
+
+
+def ClimbNext(flags_dict, climb_spec):
+  """Get the flags who are different from flags_dict by climb_spec.
+
+  Args:
+    flags_dict: The dictionary containing the original flags whose neighbors are
+      to be explored.
+    climb_spec: The spec in the flags_dict is to be changed.
+
+  Returns:
+    A dictionary of neighbor flags.
+  """
+
+  result = flags.Search(climb_spec)
+
+  # If the flags do not contain the spec.
+  if climb_spec not in flags_dict:
+    results = flags_dict.copy()
+
+    if result:
+      # Numeric flags.
+      results[climb_spec] = Flag(climb_spec, int(result.group('start')))
+    else:
+      # Boolean flags.
+      results[climb_spec] = Flag(climb_spec)
+
+    return [results]
+
+  # The flags contain the spec.
+  if not result:
+    # Boolean flags.
+    results = flags_dict.copy()
+    del results[climb_spec]
+    return [results]
+
+  # Numeric flags.
+  flag = flags_dict[climb_spec]
+
+  # The value of the flag having spec.
+  value = flag.GetValue()
+  results = []
+
+  if value + 1 < int(result.group('end')):
+    # If the value is not the end value, explore the value that is 1 larger than
+    # the current value.
+    neighbor = flags_dict.copy()
+    neighbor[climb_spec] = Flag(climb_spec, value + 1)
+    results.append(neighbor)
+
+  if value > int(result.group('start')):
+    # If the value is not the start value, explore the value that is 1 lesser
+    # than the current value.
+    neighbor = flags_dict.copy()
+    neighbor[climb_spec] = Flag(climb_spec, value - 1)
+    results.append(neighbor)
+  else:
+    # Delete the value.
+    neighbor = flags_dict.copy()
+    del neighbor[climb_spec]
+    results.append(neighbor)
+
+  return results