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| 1 #!/usr/bin/env python |
| 2 |
| 3 # Copyright (c) 2010, Google Inc. |
| 4 # All rights reserved. |
| 5 # |
| 6 # Redistribution and use in source and binary forms, with or without |
| 7 # modification, are permitted provided that the following conditions are |
| 8 # met: |
| 9 # |
| 10 # * Redistributions of source code must retain the above copyright |
| 11 # notice, this list of conditions and the following disclaimer. |
| 12 # * Redistributions in binary form must reproduce the above |
| 13 # copyright notice, this list of conditions and the following disclaimer |
| 14 # in the documentation and/or other materials provided with the |
| 15 # distribution. |
| 16 # * Neither the name of Google Inc. nor the names of its |
| 17 # contributors may be used to endorse or promote products derived from |
| 18 # this software without specific prior written permission. |
| 19 # |
| 20 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| 21 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| 22 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| 23 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| 24 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| 25 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| 26 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| 27 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| 28 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| 29 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| 30 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 31 |
| 32 """Module to enforce different constraints on flags. |
| 33 |
| 34 A validator represents an invariant, enforced over a one or more flags. |
| 35 See 'FLAGS VALIDATORS' in gflags.py's docstring for a usage manual. |
| 36 """ |
| 37 |
| 38 __author__ = 'olexiy@google.com (Olexiy Oryeshko)' |
| 39 |
| 40 |
| 41 class Error(Exception): |
| 42 """Thrown If validator constraint is not satisfied.""" |
| 43 |
| 44 |
| 45 class Validator(object): |
| 46 """Base class for flags validators. |
| 47 |
| 48 Users should NOT overload these classes, and use gflags.Register... |
| 49 methods instead. |
| 50 """ |
| 51 |
| 52 # Used to assign each validator an unique insertion_index |
| 53 validators_count = 0 |
| 54 |
| 55 def __init__(self, checker, message): |
| 56 """Constructor to create all validators. |
| 57 |
| 58 Args: |
| 59 checker: function to verify the constraint. |
| 60 Input of this method varies, see SimpleValidator and |
| 61 DictionaryValidator for a detailed description. |
| 62 message: string, error message to be shown to the user |
| 63 """ |
| 64 self.checker = checker |
| 65 self.message = message |
| 66 Validator.validators_count += 1 |
| 67 # Used to assert validators in the order they were registered (CL/18694236) |
| 68 self.insertion_index = Validator.validators_count |
| 69 |
| 70 def Verify(self, flag_values): |
| 71 """Verify that constraint is satisfied. |
| 72 |
| 73 flags library calls this method to verify Validator's constraint. |
| 74 Args: |
| 75 flag_values: gflags.FlagValues, containing all flags |
| 76 Raises: |
| 77 Error: if constraint is not satisfied. |
| 78 """ |
| 79 param = self._GetInputToCheckerFunction(flag_values) |
| 80 if not self.checker(param): |
| 81 raise Error(self.message) |
| 82 |
| 83 def GetFlagsNames(self): |
| 84 """Return the names of the flags checked by this validator. |
| 85 |
| 86 Returns: |
| 87 [string], names of the flags |
| 88 """ |
| 89 raise NotImplementedError('This method should be overloaded') |
| 90 |
| 91 def PrintFlagsWithValues(self, flag_values): |
| 92 raise NotImplementedError('This method should be overloaded') |
| 93 |
| 94 def _GetInputToCheckerFunction(self, flag_values): |
| 95 """Given flag values, construct the input to be given to checker. |
| 96 |
| 97 Args: |
| 98 flag_values: gflags.FlagValues, containing all flags. |
| 99 Returns: |
| 100 Return type depends on the specific validator. |
| 101 """ |
| 102 raise NotImplementedError('This method should be overloaded') |
| 103 |
| 104 |
| 105 class SimpleValidator(Validator): |
| 106 """Validator behind RegisterValidator() method. |
| 107 |
| 108 Validates that a single flag passes its checker function. The checker function |
| 109 takes the flag value and returns True (if value looks fine) or, if flag value |
| 110 is not valid, either returns False or raises an Exception.""" |
| 111 def __init__(self, flag_name, checker, message): |
| 112 """Constructor. |
| 113 |
| 114 Args: |
| 115 flag_name: string, name of the flag. |
| 116 checker: function to verify the validator. |
| 117 input - value of the corresponding flag (string, boolean, etc). |
| 118 output - Boolean. Must return True if validator constraint is satisfied. |
| 119 If constraint is not satisfied, it should either return False or |
| 120 raise Error. |
| 121 message: string, error message to be shown to the user if validator's |
| 122 condition is not satisfied |
| 123 """ |
| 124 super(SimpleValidator, self).__init__(checker, message) |
| 125 self.flag_name = flag_name |
| 126 |
| 127 def GetFlagsNames(self): |
| 128 return [self.flag_name] |
| 129 |
| 130 def PrintFlagsWithValues(self, flag_values): |
| 131 return 'flag --%s=%s' % (self.flag_name, flag_values[self.flag_name].value) |
| 132 |
| 133 def _GetInputToCheckerFunction(self, flag_values): |
| 134 """Given flag values, construct the input to be given to checker. |
| 135 |
| 136 Args: |
| 137 flag_values: gflags.FlagValues |
| 138 Returns: |
| 139 value of the corresponding flag. |
| 140 """ |
| 141 return flag_values[self.flag_name].value |
| 142 |
| 143 |
| 144 class DictionaryValidator(Validator): |
| 145 """Validator behind RegisterDictionaryValidator method. |
| 146 |
| 147 Validates that flag values pass their common checker function. The checker |
| 148 function takes flag values and returns True (if values look fine) or, |
| 149 if values are not valid, either returns False or raises an Exception. |
| 150 """ |
| 151 def __init__(self, flag_names, checker, message): |
| 152 """Constructor. |
| 153 |
| 154 Args: |
| 155 flag_names: [string], containing names of the flags used by checker. |
| 156 checker: function to verify the validator. |
| 157 input - dictionary, with keys() being flag_names, and value for each |
| 158 key being the value of the corresponding flag (string, boolean, etc). |
| 159 output - Boolean. Must return True if validator constraint is satisfied. |
| 160 If constraint is not satisfied, it should either return False or |
| 161 raise Error. |
| 162 message: string, error message to be shown to the user if validator's |
| 163 condition is not satisfied |
| 164 """ |
| 165 super(DictionaryValidator, self).__init__(checker, message) |
| 166 self.flag_names = flag_names |
| 167 |
| 168 def _GetInputToCheckerFunction(self, flag_values): |
| 169 """Given flag values, construct the input to be given to checker. |
| 170 |
| 171 Args: |
| 172 flag_values: gflags.FlagValues |
| 173 Returns: |
| 174 dictionary, with keys() being self.lag_names, and value for each key |
| 175 being the value of the corresponding flag (string, boolean, etc). |
| 176 """ |
| 177 return dict([key, flag_values[key].value] for key in self.flag_names) |
| 178 |
| 179 def PrintFlagsWithValues(self, flag_values): |
| 180 prefix = 'flags ' |
| 181 flags_with_values = [] |
| 182 for key in self.flag_names: |
| 183 flags_with_values.append('%s=%s' % (key, flag_values[key].value)) |
| 184 return prefix + ', '.join(flags_with_values) |
| 185 |
| 186 def GetFlagsNames(self): |
| 187 return self.flag_names |
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