| # 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 that are different from |flags_dict| by |climb_spec|. |
| |
| Given a set of flags, |flags_dict|, return a new set of flags that are |
| adjacent along the flag spec |climb_spec|. |
| |
| An example flags_dict is {foo=[1-9]:foo=5, bar=[1-5]:bar=2} and climb_spec is |
| bar=[1-5]. This method changes the flag that contains the spec bar=[1-5]. The |
| results are its neighbors dictionaries, i.e., {foo=[1-9]:foo=5, |
| bar=[1-5]:bar=1} and {foo=[1-9]:foo=5, bar=[1-5]:bar=3}. |
| |
| 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. The spec is a |
| definition in the little language, a string with escaped sequences of the |
| form [<start>-<end>] where start and end is an positive integer for a |
| fillable value. An example of a spec is "foo[0-9]". |
| |
| Returns: |
| List of dictionaries of neighbor flags. |
| """ |
| |
| # This method searches for a pattern [start-end] in the spec. If the spec |
| # contains this pattern, it is a numeric flag. Otherwise it is a boolean flag. |
| # For example, -finline-limit=[1-1000] is a numeric flag and -falign-jumps is |
| # a boolean flag. |
| numeric_flag_match = flags.Search(climb_spec) |
| |
| # If the flags do not contain the spec. |
| if climb_spec not in flags_dict: |
| results = flags_dict.copy() |
| |
| if numeric_flag_match: |
| # Numeric flags. |
| results[climb_spec] = Flag(climb_spec, |
| int(numeric_flag_match.group('start'))) |
| else: |
| # Boolean flags. |
| results[climb_spec] = Flag(climb_spec) |
| |
| return [results] |
| |
| # The flags contain the spec. |
| if not numeric_flag_match: |
| # Boolean flags. |
| results = flags_dict.copy() |
| |
| # Turn off the flag. A flag is turned off if it is not presented in the |
| # flags_dict. |
| 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(numeric_flag_match.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(numeric_flag_match.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, i.e., turn off the flag. A flag is turned off if it is |
| # not presented in the flags_dict. |
| neighbor = flags_dict.copy() |
| del neighbor[climb_spec] |
| results.append(neighbor) |
| |
| return results |