1# Copyright 2013 The ChromiumOS Authors 2# Use of this source code is governed by a BSD-style license that can be 3# found in the LICENSE file. 4"""Utility functions to explore the neighbor flags. 5 6Part of the Chrome build flags optimization. 7""" 8 9__author__ = "[email protected] (Yuheng Long)" 10 11import flags 12from flags import Flag 13 14 15def ClimbNext(flags_dict, climb_spec): 16 """Get the flags that are different from |flags_dict| by |climb_spec|. 17 18 Given a set of flags, |flags_dict|, return a new set of flags that are 19 adjacent along the flag spec |climb_spec|. 20 21 An example flags_dict is {foo=[1-9]:foo=5, bar=[1-5]:bar=2} and climb_spec is 22 bar=[1-5]. This method changes the flag that contains the spec bar=[1-5]. The 23 results are its neighbors dictionaries, i.e., {foo=[1-9]:foo=5, 24 bar=[1-5]:bar=1} and {foo=[1-9]:foo=5, bar=[1-5]:bar=3}. 25 26 Args: 27 flags_dict: The dictionary containing the original flags whose neighbors are 28 to be explored. 29 climb_spec: The spec in the flags_dict is to be changed. The spec is a 30 definition in the little language, a string with escaped sequences of the 31 form [<start>-<end>] where start and end is an positive integer for a 32 fillable value. An example of a spec is "foo[0-9]". 33 34 Returns: 35 List of dictionaries of neighbor flags. 36 """ 37 38 # This method searches for a pattern [start-end] in the spec. If the spec 39 # contains this pattern, it is a numeric flag. Otherwise it is a boolean flag. 40 # For example, -finline-limit=[1-1000] is a numeric flag and -falign-jumps is 41 # a boolean flag. 42 numeric_flag_match = flags.Search(climb_spec) 43 44 # If the flags do not contain the spec. 45 if climb_spec not in flags_dict: 46 results = flags_dict.copy() 47 48 if numeric_flag_match: 49 # Numeric flags. 50 results[climb_spec] = Flag( 51 climb_spec, int(numeric_flag_match.group("start")) 52 ) 53 else: 54 # Boolean flags. 55 results[climb_spec] = Flag(climb_spec) 56 57 return [results] 58 59 # The flags contain the spec. 60 if not numeric_flag_match: 61 # Boolean flags. 62 results = flags_dict.copy() 63 64 # Turn off the flag. A flag is turned off if it is not presented in the 65 # flags_dict. 66 del results[climb_spec] 67 return [results] 68 69 # Numeric flags. 70 flag = flags_dict[climb_spec] 71 72 # The value of the flag having spec. 73 value = flag.GetValue() 74 results = [] 75 76 if value + 1 < int(numeric_flag_match.group("end")): 77 # If the value is not the end value, explore the value that is 1 larger than 78 # the current value. 79 neighbor = flags_dict.copy() 80 neighbor[climb_spec] = Flag(climb_spec, value + 1) 81 results.append(neighbor) 82 83 if value > int(numeric_flag_match.group("start")): 84 # If the value is not the start value, explore the value that is 1 lesser 85 # than the current value. 86 neighbor = flags_dict.copy() 87 neighbor[climb_spec] = Flag(climb_spec, value - 1) 88 results.append(neighbor) 89 else: 90 # Delete the value, i.e., turn off the flag. A flag is turned off if it is 91 # not presented in the flags_dict. 92 neighbor = flags_dict.copy() 93 del neighbor[climb_spec] 94 results.append(neighbor) 95 96 return results 97