python: reimplement the babeltrace package as a bt2 wrapper

[babeltrace.git] / bindings / python / babeltrace / babeltrace / reader_field_definition.py

diff --git a/bindings/python/babeltrace/babeltrace/reader_field_definition.py b/bindings/python/babeltrace/babeltrace/reader_field_definition.py
new file mode 100644 (file)
index 0000000..1485e5b
--- /dev/null
+++ b/bindings/python/babeltrace/babeltrace/reader_field_definition.py
@@ -0,0 +1,101 @@
+# The MIT License (MIT)
+#
+# Copyright (c) 2013-2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in
+# all copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+# THE SOFTWARE.
+
+import bt2
+import babeltrace.common as common
+import babeltrace.reader_field_declaration as reader_field_declaration
+
+class FieldError(Exception):
+    """
+    Field error, raised when the value of a field cannot be accessed.
+    """
+
+    def __init__(self, value):
+        self.value = value
+
+    def __str__(self):
+        return repr(self.value)
+
+class _Definition:
+    def __init__(self, scope_id, field, name):
+        self._scope_id = scope_id
+        self._field = field
+        self._name = name
+
+    @property
+    def name(self):
+        """Return the name of a field or None on error."""
+
+        return self._name
+
+    @property
+    def type(self):
+        """Return the type of a field or -1 if unknown."""
+
+        try:
+            return _OBJ_TO_TYPE_ID[type(self._field)]
+        except KeyError:
+            return -1
+
+    @property
+    def declaration(self):
+        """Return the associated Definition object."""
+
+        return reader_field_declaration._create_field_declaration(
+            self._field.field_type, self._name, self.scope)
+
+    @property
+    def value(self):
+        """
+        Return the value associated with the field according to its type.
+        Return None on error.
+        """
+
+        try:
+            if type(self._field) in (bt2._ArrayField, bt2._SequenceField):
+                elem_ft = self._field.field_type.element_field_type
+
+                if type(elem_ft) is bt2.IntegerFieldType:
+                    if elem_ft.size == 8 and elem_ft.encoding != bt2.Encoding.NONE:
+                        return bytes(x for x in self._field._value if x != 0).decode()
+
+            return self._field._value
+        except bt2.Error:
+            return
+
+    @property
+    def scope(self):
+        """Return the scope of a field or None on error."""
+
+        return self._scope_id
+
+
+_OBJ_TO_TYPE_ID = {
+    bt2._IntegerField: common.CTFTypeId.INTEGER,
+    bt2._FloatingPointNumberField: common.CTFTypeId.FLOAT,
+    bt2._EnumerationField: common.CTFTypeId.ENUM,
+    bt2._StringField: common.CTFTypeId.STRING,
+    bt2._StructureField: common.CTFTypeId.STRUCT,
+    bt2._ArrayField: common.CTFTypeId.ARRAY,
+    bt2._SequenceField: common.CTFTypeId.SEQUENCE,
+    bt2._VariantField: common.CTFTypeId.VARIANT,
+}