bindings/python/babeltrace/babeltrace/reader_field_definition.py

   1 # The MIT License (MIT)
   2 #
   3 # Copyright (c) 2013-2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   4 #
   5 # Permission is hereby granted, free of charge, to any person obtaining a copy
   6 # of this software and associated documentation files (the "Software"), to deal
   7 # in the Software without restriction, including without limitation the rights
   8 # to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
   9 # copies of the Software, and to permit persons to whom the Software is
  10 # furnished to do so, subject to the following conditions:
  11 #
  12 # The above copyright notice and this permission notice shall be included in
  13 # all copies or substantial portions of the Software.
  14 #
  15 # THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16 # IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17 # FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  18 # AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19 # LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  20 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
  21 # THE SOFTWARE.
  22
  23 import bt2
  24 import babeltrace.common as common
  25 import babeltrace.reader_field_declaration as reader_field_declaration
  26
  27 class FieldError(Exception):
  28     """
  29     Field error, raised when the value of a field cannot be accessed.
  30     """
  31
  32     def __init__(self, value):
  33         self.value = value
  34
  35     def __str__(self):
  36         return repr(self.value)
  37
  38 class _Definition:
  39     def __init__(self, scope_id, field, name):
  40         self._scope_id = scope_id
  41         self._field = field
  42         self._name = name
  43
  44     @property
  45     def name(self):
  46         """Return the name of a field or None on error."""
  47
  48         return self._name
  49
  50     @property
  51     def type(self):
  52         """Return the type of a field or -1 if unknown."""
  53
  54         try:
  55             return _OBJ_TO_TYPE_ID[type(self._field)]
  56         except KeyError:
  57             return -1
  58
  59     @property
  60     def declaration(self):
  61         """Return the associated Definition object."""
  62
  63         return reader_field_declaration._create_field_declaration(
  64             self._field.field_type, self._name, self.scope)
  65
  66     @property
  67     def value(self):
  68         """
  69         Return the value associated with the field according to its type.
  70         Return None on error.
  71         """
  72
  73         try:
  74             if type(self._field) in (bt2._ArrayField, bt2._SequenceField):
  75                 elem_ft = self._field.field_type.element_field_type
  76
  77                 if type(elem_ft) is bt2.IntegerFieldType:
  78                     if elem_ft.size == 8 and elem_ft.encoding != bt2.Encoding.NONE:
  79                         return bytes(x for x in self._field._value if x != 0).decode()
  80
  81             return self._field._value
  82         except bt2.Error:
  83             return
  84
  85     @property
  86     def scope(self):
  87         """Return the scope of a field or None on error."""
  88
  89         return self._scope_id
  90
  91
  92 _OBJ_TO_TYPE_ID = {
  93     bt2._IntegerField: common.CTFTypeId.INTEGER,
  94     bt2._FloatingPointNumberField: common.CTFTypeId.FLOAT,
  95     bt2._EnumerationField: common.CTFTypeId.ENUM,
  96     bt2._StringField: common.CTFTypeId.STRING,
  97     bt2._StructureField: common.CTFTypeId.STRUCT,
  98     bt2._ArrayField: common.CTFTypeId.ARRAY,
  99     bt2._SequenceField: common.CTFTypeId.SEQUENCE,
 100     bt2._VariantField: common.CTFTypeId.VARIANT,
 101 }