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# Copyright 2014 Google Inc. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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from . import util
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from ._version import __version__
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from .builder import Builder
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from .compat import range_func as compat_range
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from .table import Table
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# Copyright 2019 Google Inc. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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||||
#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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||||
# limitations under the License.
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# Placeholder, to be updated during the release process
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# by the setup.py
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__version__ = "25.12.19"
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@@ -0,0 +1,858 @@
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# Copyright 2014 Google Inc. All rights reserved.
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
|
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# You may obtain a copy of the License at
|
||||
#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import warnings
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from . import compat
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from . import encode
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from . import number_types as N
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from . import packer
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from .compat import memoryview_type
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from .compat import NumpyRequiredForThisFeature, import_numpy
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from .compat import range_func
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from .number_types import (SOffsetTFlags, UOffsetTFlags, VOffsetTFlags)
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np = import_numpy()
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## @file
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## @addtogroup flatbuffers_python_api
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## @{
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|
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## @cond FLATBUFFERS_INTERNAL
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class OffsetArithmeticError(RuntimeError):
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"""Error caused by an Offset arithmetic error.
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Probably caused by bad writing of fields. This is considered an unreachable
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situation in normal circumstances.
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"""
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|
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pass
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|
||||
|
||||
class IsNotNestedError(RuntimeError):
|
||||
"""Error caused by using a Builder to write Object data when not inside
|
||||
|
||||
an Object.
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"""
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|
||||
pass
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||||
|
||||
|
||||
class IsNestedError(RuntimeError):
|
||||
"""Error caused by using a Builder to begin an Object when an Object is
|
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|
||||
already being built.
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"""
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||||
|
||||
pass
|
||||
|
||||
|
||||
class StructIsNotInlineError(RuntimeError):
|
||||
"""Error caused by using a Builder to write a Struct at a location that
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is not the current Offset.
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"""
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||||
|
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pass
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||||
|
||||
|
||||
class BuilderSizeError(RuntimeError):
|
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"""Error caused by causing a Builder to exceed the hardcoded limit of 2
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|
||||
gigabytes.
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"""
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||||
|
||||
pass
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||||
|
||||
|
||||
class BuilderNotFinishedError(RuntimeError):
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"""Error caused by not calling `Finish` before calling `Output`."""
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||||
|
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pass
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||||
|
||||
|
||||
class EndVectorLengthMismatched(RuntimeError):
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||||
"""The number of elements passed to EndVector does not match the number
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specified in StartVector.
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"""
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||||
|
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pass
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|
||||
|
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# VtableMetadataFields is the count of metadata fields in each vtable.
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VtableMetadataFields = 2
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## @endcond
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||||
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class Builder(object):
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"""A Builder is used to construct one or more FlatBuffers.
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Typically, Builder objects will be used from code generated by the `flatc`
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compiler.
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|
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A Builder constructs byte buffers in a last-first manner for simplicity and
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performance during reading.
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Internally, a Builder is a state machine for creating FlatBuffer objects.
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It holds the following internal state:
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- Bytes: an array of bytes.
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- current_vtable: a list of integers.
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- vtables: a hash of vtable entries.
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|
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Attributes:
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Bytes: The internal `bytearray` for the Builder.
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finished: A boolean determining if the Builder has been finalized.
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"""
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## @cond FLATBUFFERS_INTENRAL
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__slots__ = (
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"Bytes",
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"current_vtable",
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"head",
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"minalign",
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"objectEnd",
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"vtables",
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"nested",
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"forceDefaults",
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"finished",
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"vectorNumElems",
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"sharedStrings",
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)
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"""Maximum buffer size constant, in bytes.
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Builder will never allow it's buffer grow over this size.
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Currently equals 2Gb.
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"""
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MAX_BUFFER_SIZE = 2**31
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## @endcond
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def __init__(self, initialSize=1024):
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"""Initializes a Builder of size `initial_size`.
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The internal buffer is grown as needed.
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"""
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if not (0 <= initialSize <= Builder.MAX_BUFFER_SIZE):
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msg = "flatbuffers: Cannot create Builder larger than 2 gigabytes."
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raise BuilderSizeError(msg)
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self.Bytes = bytearray(initialSize)
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## @cond FLATBUFFERS_INTERNAL
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self.current_vtable = None
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self.head = UOffsetTFlags.py_type(initialSize)
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self.minalign = 1
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self.objectEnd = None
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self.vtables = {}
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self.nested = False
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self.forceDefaults = False
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self.sharedStrings = None
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## @endcond
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self.finished = False
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def Clear(self):
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## @cond FLATBUFFERS_INTERNAL
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self.current_vtable = None
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self.head = len(self.Bytes)
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self.minalign = 1
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self.objectEnd = None
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self.vtables = {}
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self.nested = False
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self.forceDefaults = False
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||||
self.sharedStrings = None
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self.vectorNumElems = None
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||||
## @endcond
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||||
self.finished = False
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||||
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||||
def Output(self):
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||||
"""Return the portion of the buffer that has been used for writing data.
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||||
|
||||
This is the typical way to access the FlatBuffer data inside the
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builder. If you try to access `Builder.Bytes` directly, you would need
|
||||
to manually index it with `Head()`, since the buffer is constructed
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||||
backwards.
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||||
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||||
It raises BuilderNotFinishedError if the buffer has not been finished
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||||
with `Finish`.
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||||
"""
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||||
if not self.finished:
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raise BuilderNotFinishedError()
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||||
return self.Bytes[self.head :]
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||||
## @cond FLATBUFFERS_INTERNAL
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||||
def StartObject(self, numfields):
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||||
"""StartObject initializes bookkeeping for writing a new object."""
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||||
self.assertNotNested()
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||||
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||||
# use 32-bit offsets so that arithmetic doesn't overflow.
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self.current_vtable = [0] * numfields
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self.objectEnd = self.Offset()
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self.nested = True
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def WriteVtable(self):
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"""WriteVtable serializes the vtable for the current object, if needed.
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||||
Before writing out the vtable, this checks pre-existing vtables for
|
||||
equality to this one. If an equal vtable is found, point the object to
|
||||
the existing vtable and return.
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||||
|
||||
Because vtable values are sensitive to alignment of object data, not
|
||||
all logically-equal vtables will be deduplicated.
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||||
|
||||
A vtable has the following format:
|
||||
<VOffsetT: size of the vtable in bytes, including this value>
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<VOffsetT: size of the object in bytes, including the vtable offset>
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||||
<VOffsetT: offset for a field> * N, where N is the number of fields
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||||
in the schema for this type. Includes deprecated fields.
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||||
Thus, a vtable is made of 2 + N elements, each VOffsetT bytes wide.
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||||
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||||
An object has the following format:
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||||
<SOffsetT: offset to this object's vtable (may be negative)>
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||||
<byte: data>+
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||||
"""
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||||
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||||
# Prepend a zero scalar to the object. Later in this function we'll
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# write an offset here that points to the object's vtable:
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||||
self.PrependSOffsetTRelative(0)
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||||
objectOffset = self.Offset()
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||||
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||||
vtKey = []
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||||
trim = True
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||||
for elem in reversed(self.current_vtable):
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||||
if elem == 0:
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||||
if trim:
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||||
continue
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else:
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||||
elem = objectOffset - elem
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||||
trim = False
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||||
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||||
vtKey.append(elem)
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||||
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||||
objectSize = UOffsetTFlags.py_type(objectOffset - self.objectEnd)
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||||
vtKey.append(objectSize)
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||||
vtKey = tuple(vtKey)
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||||
# calculate the size of the object
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vt2Offset = self.vtables.get(vtKey)
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if vt2Offset is None:
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||||
# Did not find a vtable, so write this one to the buffer.
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||||
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||||
# Write out the current vtable in reverse , because
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||||
# serialization occurs in last-first order:
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||||
i = len(self.current_vtable) - 1
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||||
trailing = 0
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||||
trim = True
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||||
while i >= 0:
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||||
off = 0
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||||
elem = self.current_vtable[i]
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||||
i -= 1
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||||
|
||||
if elem == 0:
|
||||
if trim:
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||||
trailing += 1
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||||
continue
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||||
else:
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||||
# Forward reference to field;
|
||||
# use 32bit number to ensure no overflow:
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||||
off = objectOffset - elem
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||||
trim = False
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||||
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||||
self.PrependVOffsetT(off)
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||||
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||||
# The two metadata fields are written last.
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||||
|
||||
# First, store the object bytesize:
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||||
self.PrependVOffsetT(VOffsetTFlags.py_type(objectSize))
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||||
|
||||
# Second, store the vtable bytesize:
|
||||
vBytes = len(self.current_vtable) - trailing + VtableMetadataFields
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||||
vBytes *= N.VOffsetTFlags.bytewidth
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||||
self.PrependVOffsetT(VOffsetTFlags.py_type(vBytes))
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||||
|
||||
# Next, write the offset to the new vtable in the
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||||
# already-allocated SOffsetT at the beginning of this object:
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||||
objectStart = SOffsetTFlags.py_type(len(self.Bytes) - objectOffset)
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||||
encode.Write(
|
||||
packer.soffset,
|
||||
self.Bytes,
|
||||
objectStart,
|
||||
SOffsetTFlags.py_type(self.Offset() - objectOffset),
|
||||
)
|
||||
|
||||
# Finally, store this vtable in memory for future
|
||||
# deduplication:
|
||||
self.vtables[vtKey] = self.Offset()
|
||||
else:
|
||||
# Found a duplicate vtable.
|
||||
objectStart = SOffsetTFlags.py_type(len(self.Bytes) - objectOffset)
|
||||
self.head = UOffsetTFlags.py_type(objectStart)
|
||||
|
||||
# Write the offset to the found vtable in the
|
||||
# already-allocated SOffsetT at the beginning of this object:
|
||||
encode.Write(
|
||||
packer.soffset,
|
||||
self.Bytes,
|
||||
self.Head(),
|
||||
SOffsetTFlags.py_type(vt2Offset - objectOffset),
|
||||
)
|
||||
|
||||
self.current_vtable = None
|
||||
return objectOffset
|
||||
|
||||
def EndObject(self):
|
||||
"""EndObject writes data necessary to finish object construction."""
|
||||
self.assertNested()
|
||||
self.nested = False
|
||||
return self.WriteVtable()
|
||||
|
||||
def GrowByteBuffer(self):
|
||||
"""Doubles the size of the byteslice, and copies the old data towards
|
||||
|
||||
the end of the new buffer (since we build the buffer backwards).
|
||||
"""
|
||||
if len(self.Bytes) == Builder.MAX_BUFFER_SIZE:
|
||||
msg = "flatbuffers: cannot grow buffer beyond 2 gigabytes"
|
||||
raise BuilderSizeError(msg)
|
||||
|
||||
newSize = min(len(self.Bytes) * 2, Builder.MAX_BUFFER_SIZE)
|
||||
if newSize == 0:
|
||||
newSize = 1
|
||||
bytes2 = bytearray(newSize)
|
||||
bytes2[newSize - len(self.Bytes) :] = self.Bytes
|
||||
self.Bytes = bytes2
|
||||
|
||||
## @endcond
|
||||
|
||||
def Head(self):
|
||||
"""Get the start of useful data in the underlying byte buffer.
|
||||
|
||||
Note: unlike other functions, this value is interpreted as from the
|
||||
left.
|
||||
"""
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
return self.head
|
||||
## @endcond
|
||||
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
def Offset(self):
|
||||
"""Offset relative to the end of the buffer."""
|
||||
return len(self.Bytes) - self.head
|
||||
|
||||
def Pad(self, n):
|
||||
"""Pad places zeros at the current offset."""
|
||||
if n <= 0:
|
||||
return
|
||||
new_head = self.head - n
|
||||
self.Bytes[new_head : self.head] = b"\x00" * n
|
||||
self.head = new_head
|
||||
|
||||
def Prep(self, size, additionalBytes):
|
||||
"""Prep prepares to write an element of `size` after `additional_bytes`
|
||||
|
||||
have been written, e.g. if you write a string, you need to align
|
||||
such the int length field is aligned to SizeInt32, and the string
|
||||
data follows it directly.
|
||||
If all you need to do is align, `additionalBytes` will be 0.
|
||||
"""
|
||||
|
||||
# Track the biggest thing we've ever aligned to.
|
||||
if size > self.minalign:
|
||||
self.minalign = size
|
||||
|
||||
# Find the amount of alignment needed such that `size` is properly
|
||||
# aligned after `additionalBytes`:
|
||||
head = self.head
|
||||
buf_len = len(self.Bytes)
|
||||
alignSize = (~(buf_len - head + additionalBytes)) + 1
|
||||
alignSize &= size - 1
|
||||
|
||||
# Reallocate the buffer if needed:
|
||||
needed = alignSize + size + additionalBytes
|
||||
while head < needed:
|
||||
oldBufSize = buf_len
|
||||
self.GrowByteBuffer()
|
||||
buf_len = len(self.Bytes)
|
||||
head += buf_len - oldBufSize
|
||||
self.head = head
|
||||
self.Pad(alignSize)
|
||||
|
||||
def PrependSOffsetTRelative(self, off):
|
||||
"""PrependSOffsetTRelative prepends an SOffsetT, relative to where it
|
||||
|
||||
will be written.
|
||||
"""
|
||||
|
||||
# Ensure alignment is already done:
|
||||
self.Prep(N.SOffsetTFlags.bytewidth, 0)
|
||||
if not (off <= self.Offset()):
|
||||
msg = "flatbuffers: Offset arithmetic error."
|
||||
raise OffsetArithmeticError(msg)
|
||||
off2 = self.Offset() - off + N.SOffsetTFlags.bytewidth
|
||||
self.PlaceSOffsetT(off2)
|
||||
|
||||
## @endcond
|
||||
|
||||
def PrependUOffsetTRelative(self, off):
|
||||
"""Prepends an unsigned offset into vector data, relative to where it
|
||||
|
||||
will be written.
|
||||
"""
|
||||
|
||||
# Ensure alignment is already done:
|
||||
self.Prep(N.UOffsetTFlags.bytewidth, 0)
|
||||
if not (off <= self.Offset()):
|
||||
msg = "flatbuffers: Offset arithmetic error."
|
||||
raise OffsetArithmeticError(msg)
|
||||
off2 = self.Offset() - off + N.UOffsetTFlags.bytewidth
|
||||
self.PlaceUOffsetT(off2)
|
||||
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
def StartVector(self, elemSize, numElems, alignment):
|
||||
"""StartVector initializes bookkeeping for writing a new vector.
|
||||
|
||||
A vector has the following format:
|
||||
- <UOffsetT: number of elements in this vector>
|
||||
- <T: data>+, where T is the type of elements of this vector.
|
||||
"""
|
||||
|
||||
self.assertNotNested()
|
||||
self.nested = True
|
||||
self.vectorNumElems = numElems
|
||||
self.Prep(N.Uint32Flags.bytewidth, elemSize * numElems)
|
||||
self.Prep(alignment, elemSize * numElems) # In case alignment > int.
|
||||
return self.Offset()
|
||||
|
||||
## @endcond
|
||||
|
||||
def EndVector(self, numElems=None):
|
||||
"""EndVector writes data necessary to finish vector construction."""
|
||||
|
||||
self.assertNested()
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
self.nested = False
|
||||
## @endcond
|
||||
|
||||
if numElems:
|
||||
warnings.warn("numElems is deprecated.", DeprecationWarning, stacklevel=2)
|
||||
if numElems != self.vectorNumElems:
|
||||
raise EndVectorLengthMismatched()
|
||||
|
||||
# we already made space for this, so write without PrependUint32
|
||||
self.PlaceUOffsetT(self.vectorNumElems)
|
||||
self.vectorNumElems = None
|
||||
return self.Offset()
|
||||
|
||||
def CreateSharedString(self, s, encoding="utf-8", errors="strict"):
|
||||
"""CreateSharedString checks if the string is already written to the buffer
|
||||
|
||||
before calling CreateString.
|
||||
"""
|
||||
|
||||
if not self.sharedStrings:
|
||||
self.sharedStrings = {}
|
||||
elif s in self.sharedStrings:
|
||||
return self.sharedStrings[s]
|
||||
|
||||
off = self.CreateString(s, encoding, errors)
|
||||
self.sharedStrings[s] = off
|
||||
|
||||
return off
|
||||
|
||||
def CreateString(self, s, encoding="utf-8", errors="strict"):
|
||||
"""CreateString writes a null-terminated byte string as a vector."""
|
||||
|
||||
self.assertNotNested()
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
self.nested = True
|
||||
## @endcond
|
||||
|
||||
if isinstance(s, compat.string_types):
|
||||
x = s.encode(encoding, errors)
|
||||
elif isinstance(s, compat.binary_types):
|
||||
x = s
|
||||
else:
|
||||
raise TypeError("non-string passed to CreateString")
|
||||
|
||||
payload_len = len(x)
|
||||
self.Prep(N.UOffsetTFlags.bytewidth, (payload_len + 1) * N.Uint8Flags.bytewidth)
|
||||
self.Place(0, N.Uint8Flags)
|
||||
|
||||
new_head = self.head - payload_len
|
||||
self.head = new_head
|
||||
self.Bytes[new_head : new_head + payload_len] = x
|
||||
|
||||
self.vectorNumElems = payload_len
|
||||
return self.EndVector()
|
||||
|
||||
def CreateByteVector(self, x):
|
||||
"""CreateString writes a byte vector."""
|
||||
|
||||
self.assertNotNested()
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
self.nested = True
|
||||
## @endcond
|
||||
|
||||
if not isinstance(x, compat.binary_types):
|
||||
raise TypeError("non-byte vector passed to CreateByteVector")
|
||||
|
||||
data_len = len(x)
|
||||
self.Prep(N.UOffsetTFlags.bytewidth, data_len * N.Uint8Flags.bytewidth)
|
||||
new_head = self.head - data_len
|
||||
self.head = new_head
|
||||
self.Bytes[new_head : new_head + data_len] = x
|
||||
|
||||
self.vectorNumElems = data_len
|
||||
return self.EndVector()
|
||||
|
||||
def CreateNumpyVector(self, x):
|
||||
"""CreateNumpyVector writes a numpy array into the buffer."""
|
||||
|
||||
if np is None:
|
||||
# Numpy is required for this feature
|
||||
raise NumpyRequiredForThisFeature("Numpy was not found.")
|
||||
|
||||
if not isinstance(x, np.ndarray):
|
||||
raise TypeError("non-numpy-ndarray passed to CreateNumpyVector")
|
||||
|
||||
if x.dtype.kind not in ["b", "i", "u", "f"]:
|
||||
raise TypeError("numpy-ndarray holds elements of unsupported datatype")
|
||||
|
||||
if x.ndim > 1:
|
||||
raise TypeError("multidimensional-ndarray passed to CreateNumpyVector")
|
||||
|
||||
self.StartVector(x.itemsize, x.size, x.dtype.alignment)
|
||||
|
||||
# Ensure little endian byte ordering
|
||||
if x.dtype.str[0] == "<":
|
||||
x_lend = x
|
||||
else:
|
||||
x_lend = x.byteswap(inplace=False)
|
||||
|
||||
# tobytes ensures c_contiguous ordering
|
||||
payload = x_lend.tobytes(order="C")
|
||||
|
||||
# Calculate total length
|
||||
payload_len = len(payload)
|
||||
new_head = self.head - payload_len
|
||||
self.head = new_head
|
||||
self.Bytes[new_head : new_head + payload_len] = payload
|
||||
|
||||
self.vectorNumElems = x.size
|
||||
return self.EndVector()
|
||||
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
def assertNested(self):
|
||||
"""Check that we are in the process of building an object."""
|
||||
|
||||
if not self.nested:
|
||||
raise IsNotNestedError()
|
||||
|
||||
def assertNotNested(self):
|
||||
"""Check that no other objects are being built while making this object.
|
||||
|
||||
If not, raise an exception.
|
||||
"""
|
||||
|
||||
if self.nested:
|
||||
raise IsNestedError()
|
||||
|
||||
def assertStructIsInline(self, obj):
|
||||
"""Structs are always stored inline, so need to be created right
|
||||
|
||||
where they are used. You'll get this error if you created it
|
||||
elsewhere.
|
||||
"""
|
||||
|
||||
N.enforce_number(obj, N.UOffsetTFlags)
|
||||
if obj != self.Offset():
|
||||
msg = (
|
||||
"flatbuffers: Tried to write a Struct at an Offset that "
|
||||
"is different from the current Offset of the Builder."
|
||||
)
|
||||
raise StructIsNotInlineError(msg)
|
||||
|
||||
def Slot(self, slotnum):
|
||||
"""Slot sets the vtable key `voffset` to the current location in the
|
||||
|
||||
buffer.
|
||||
"""
|
||||
self.assertNested()
|
||||
self.current_vtable[slotnum] = self.Offset()
|
||||
|
||||
## @endcond
|
||||
|
||||
def __Finish(self, rootTable, sizePrefix, file_identifier=None):
|
||||
"""Finish finalizes a buffer, pointing to the given `rootTable`."""
|
||||
N.enforce_number(rootTable, N.UOffsetTFlags)
|
||||
|
||||
prepSize = N.UOffsetTFlags.bytewidth
|
||||
if file_identifier is not None:
|
||||
prepSize += N.Int32Flags.bytewidth
|
||||
if sizePrefix:
|
||||
prepSize += N.Int32Flags.bytewidth
|
||||
self.Prep(self.minalign, prepSize)
|
||||
|
||||
if file_identifier is not None:
|
||||
self.Prep(N.UOffsetTFlags.bytewidth, encode.FILE_IDENTIFIER_LENGTH)
|
||||
|
||||
# Convert bytes object file_identifier to an array of 4 8-bit integers,
|
||||
# and use big-endian to enforce size compliance.
|
||||
# https://docs.python.org/2/library/struct.html#format-characters
|
||||
file_identifier = N.struct.unpack(">BBBB", file_identifier)
|
||||
for i in range(encode.FILE_IDENTIFIER_LENGTH - 1, -1, -1):
|
||||
# Place the bytes of the file_identifer in reverse order:
|
||||
self.Place(file_identifier[i], N.Uint8Flags)
|
||||
|
||||
self.PrependUOffsetTRelative(rootTable)
|
||||
if sizePrefix:
|
||||
size = len(self.Bytes) - self.head
|
||||
N.enforce_number(size, N.Int32Flags)
|
||||
self.PrependInt32(size)
|
||||
self.finished = True
|
||||
return self.head
|
||||
|
||||
def Finish(self, rootTable, file_identifier=None):
|
||||
"""Finish finalizes a buffer, pointing to the given `rootTable`."""
|
||||
return self.__Finish(rootTable, False, file_identifier=file_identifier)
|
||||
|
||||
def FinishSizePrefixed(self, rootTable, file_identifier=None):
|
||||
"""Finish finalizes a buffer, pointing to the given `rootTable`,
|
||||
|
||||
with the size prefixed.
|
||||
"""
|
||||
return self.__Finish(rootTable, True, file_identifier=file_identifier)
|
||||
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
def Prepend(self, flags, off):
|
||||
self.Prep(flags.bytewidth, 0)
|
||||
self.Place(off, flags)
|
||||
|
||||
def PrependSlot(self, flags, o, x, d):
|
||||
if x is not None:
|
||||
N.enforce_number(x, flags)
|
||||
if d is not None:
|
||||
N.enforce_number(d, flags)
|
||||
if x != d or (self.forceDefaults and d is not None):
|
||||
self.Prepend(flags, x)
|
||||
self.Slot(o)
|
||||
|
||||
def PrependBoolSlot(self, *args):
|
||||
self.PrependSlot(N.BoolFlags, *args)
|
||||
|
||||
def PrependByteSlot(self, *args):
|
||||
self.PrependSlot(N.Uint8Flags, *args)
|
||||
|
||||
def PrependUint8Slot(self, *args):
|
||||
self.PrependSlot(N.Uint8Flags, *args)
|
||||
|
||||
def PrependUint16Slot(self, *args):
|
||||
self.PrependSlot(N.Uint16Flags, *args)
|
||||
|
||||
def PrependUint32Slot(self, *args):
|
||||
self.PrependSlot(N.Uint32Flags, *args)
|
||||
|
||||
def PrependUint64Slot(self, *args):
|
||||
self.PrependSlot(N.Uint64Flags, *args)
|
||||
|
||||
def PrependInt8Slot(self, *args):
|
||||
self.PrependSlot(N.Int8Flags, *args)
|
||||
|
||||
def PrependInt16Slot(self, *args):
|
||||
self.PrependSlot(N.Int16Flags, *args)
|
||||
|
||||
def PrependInt32Slot(self, *args):
|
||||
self.PrependSlot(N.Int32Flags, *args)
|
||||
|
||||
def PrependInt64Slot(self, *args):
|
||||
self.PrependSlot(N.Int64Flags, *args)
|
||||
|
||||
def PrependFloat32Slot(self, *args):
|
||||
self.PrependSlot(N.Float32Flags, *args)
|
||||
|
||||
def PrependFloat64Slot(self, *args):
|
||||
self.PrependSlot(N.Float64Flags, *args)
|
||||
|
||||
def PrependUOffsetTRelativeSlot(self, o, x, d):
|
||||
"""PrependUOffsetTRelativeSlot prepends an UOffsetT onto the object at
|
||||
|
||||
vtable slot `o`. If value `x` equals default `d`, then the slot will
|
||||
be set to zero and no other data will be written.
|
||||
"""
|
||||
|
||||
if x != d or self.forceDefaults:
|
||||
self.PrependUOffsetTRelative(x)
|
||||
self.Slot(o)
|
||||
|
||||
def PrependStructSlot(self, v, x, d):
|
||||
"""PrependStructSlot prepends a struct onto the object at vtable slot `o`.
|
||||
|
||||
Structs are stored inline, so nothing additional is being added. In
|
||||
generated code, `d` is always 0.
|
||||
"""
|
||||
|
||||
N.enforce_number(d, N.UOffsetTFlags)
|
||||
if x != d:
|
||||
self.assertStructIsInline(x)
|
||||
self.Slot(v)
|
||||
|
||||
## @endcond
|
||||
|
||||
def PrependBool(self, x):
|
||||
"""Prepend a `bool` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.BoolFlags, x)
|
||||
|
||||
def PrependByte(self, x):
|
||||
"""Prepend a `byte` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Uint8Flags, x)
|
||||
|
||||
def PrependUint8(self, x):
|
||||
"""Prepend an `uint8` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Uint8Flags, x)
|
||||
|
||||
def PrependUint16(self, x):
|
||||
"""Prepend an `uint16` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Uint16Flags, x)
|
||||
|
||||
def PrependUint32(self, x):
|
||||
"""Prepend an `uint32` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Uint32Flags, x)
|
||||
|
||||
def PrependUint64(self, x):
|
||||
"""Prepend an `uint64` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Uint64Flags, x)
|
||||
|
||||
def PrependInt8(self, x):
|
||||
"""Prepend an `int8` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Int8Flags, x)
|
||||
|
||||
def PrependInt16(self, x):
|
||||
"""Prepend an `int16` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Int16Flags, x)
|
||||
|
||||
def PrependInt32(self, x):
|
||||
"""Prepend an `int32` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Int32Flags, x)
|
||||
|
||||
def PrependInt64(self, x):
|
||||
"""Prepend an `int64` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Int64Flags, x)
|
||||
|
||||
def PrependFloat32(self, x):
|
||||
"""Prepend a `float32` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Float32Flags, x)
|
||||
|
||||
def PrependFloat64(self, x):
|
||||
"""Prepend a `float64` to the Builder buffer.
|
||||
|
||||
Note: aligns and checks for space.
|
||||
"""
|
||||
self.Prepend(N.Float64Flags, x)
|
||||
|
||||
def ForceDefaults(self, forceDefaults):
|
||||
"""In order to save space, fields that are set to their default value
|
||||
|
||||
don't get serialized into the buffer. Forcing defaults provides a
|
||||
way to manually disable this optimization. When set to `True`, will
|
||||
always serialize default values.
|
||||
"""
|
||||
self.forceDefaults = forceDefaults
|
||||
|
||||
##############################################################
|
||||
|
||||
## @cond FLATBUFFERS_INTERNAL
|
||||
def PrependVOffsetT(self, x):
|
||||
self.Prepend(N.VOffsetTFlags, x)
|
||||
|
||||
def Place(self, x, flags):
|
||||
"""Place prepends a value specified by `flags` to the Builder,
|
||||
|
||||
without checking for available space.
|
||||
"""
|
||||
|
||||
N.enforce_number(x, flags)
|
||||
new_head = self.head - flags.bytewidth
|
||||
self.head = new_head
|
||||
encode.Write(flags.packer_type, self.Bytes, new_head, x)
|
||||
|
||||
def PlaceVOffsetT(self, x):
|
||||
"""PlaceVOffsetT prepends a VOffsetT to the Builder, without checking
|
||||
|
||||
for space.
|
||||
"""
|
||||
N.enforce_number(x, N.VOffsetTFlags)
|
||||
new_head = self.head - N.VOffsetTFlags.bytewidth
|
||||
self.head = new_head
|
||||
encode.Write(packer.voffset, self.Bytes, new_head, x)
|
||||
|
||||
def PlaceSOffsetT(self, x):
|
||||
"""PlaceSOffsetT prepends a SOffsetT to the Builder, without checking
|
||||
|
||||
for space.
|
||||
"""
|
||||
N.enforce_number(x, N.SOffsetTFlags)
|
||||
new_head = self.head - N.SOffsetTFlags.bytewidth
|
||||
self.head = new_head
|
||||
encode.Write(packer.soffset, self.Bytes, new_head, x)
|
||||
|
||||
def PlaceUOffsetT(self, x):
|
||||
"""PlaceUOffsetT prepends a UOffsetT to the Builder, without checking
|
||||
|
||||
for space.
|
||||
"""
|
||||
N.enforce_number(x, N.UOffsetTFlags)
|
||||
new_head = self.head - N.UOffsetTFlags.bytewidth
|
||||
self.head = new_head
|
||||
encode.Write(packer.uoffset, self.Bytes, new_head, x)
|
||||
|
||||
## @endcond
|
||||
|
||||
## @}
|
||||
@@ -0,0 +1,91 @@
|
||||
# Copyright 2016 Google Inc. All rights reserved.
|
||||
#
|
||||
# Licensed under the Apache License, Version 2.0 (the "License");
|
||||
# you may not use this file except in compliance with the License.
|
||||
# You may obtain a copy of the License at
|
||||
#
|
||||
# http://www.apache.org/licenses/LICENSE-2.0
|
||||
#
|
||||
# Unless required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
|
||||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
# See the License for the specific language governing permissions and
|
||||
# limitations under the License.
|
||||
|
||||
"""A tiny version of `six` to help with backwards compability.
|
||||
|
||||
Also includes compatibility helpers for numpy.
|
||||
"""
|
||||
|
||||
import sys
|
||||
|
||||
PY2 = sys.version_info[0] == 2
|
||||
PY26 = sys.version_info[0:2] == (2, 6)
|
||||
PY27 = sys.version_info[0:2] == (2, 7)
|
||||
PY275 = sys.version_info[0:3] >= (2, 7, 5)
|
||||
PY3 = sys.version_info[0] == 3
|
||||
PY34 = sys.version_info[0:2] >= (3, 4)
|
||||
|
||||
if PY3:
|
||||
import importlib.machinery
|
||||
|
||||
string_types = (str,)
|
||||
binary_types = (bytes, bytearray)
|
||||
range_func = range
|
||||
memoryview_type = memoryview
|
||||
struct_bool_decl = "?"
|
||||
else:
|
||||
import imp
|
||||
|
||||
string_types = (unicode,)
|
||||
if PY26 or PY27:
|
||||
binary_types = (str, bytearray)
|
||||
else:
|
||||
binary_types = (str,)
|
||||
range_func = xrange
|
||||
if PY26 or (PY27 and not PY275):
|
||||
memoryview_type = buffer
|
||||
struct_bool_decl = "<b"
|
||||
else:
|
||||
memoryview_type = memoryview
|
||||
struct_bool_decl = "?"
|
||||
|
||||
# Helper functions to facilitate making numpy optional instead of required
|
||||
|
||||
|
||||
def import_numpy():
|
||||
"""Returns the numpy module if it exists on the system,
|
||||
|
||||
otherwise returns None.
|
||||
"""
|
||||
if PY3:
|
||||
numpy_exists = importlib.machinery.PathFinder.find_spec("numpy") is not None
|
||||
else:
|
||||
try:
|
||||
imp.find_module("numpy")
|
||||
numpy_exists = True
|
||||
except ImportError:
|
||||
numpy_exists = False
|
||||
|
||||
if numpy_exists:
|
||||
# We do this outside of try/except block in case numpy exists
|
||||
# but is not installed correctly. We do not want to catch an
|
||||
# incorrect installation which would manifest as an
|
||||
# ImportError.
|
||||
import numpy as np
|
||||
else:
|
||||
np = None
|
||||
|
||||
return np
|
||||
|
||||
|
||||
class NumpyRequiredForThisFeature(RuntimeError):
|
||||
"""Error raised when user tries to use a feature that
|
||||
|
||||
requires numpy without having numpy installed.
|
||||
"""
|
||||
|
||||
pass
|
||||
|
||||
|
||||
# NOTE: Future Jython support may require code here (look at `six`).
|
||||
@@ -0,0 +1,45 @@
|
||||
# Copyright 2014 Google Inc. All rights reserved.
|
||||
#
|
||||
# Licensed under the Apache License, Version 2.0 (the "License");
|
||||
# you may not use this file except in compliance with the License.
|
||||
# You may obtain a copy of the License at
|
||||
#
|
||||
# http://www.apache.org/licenses/LICENSE-2.0
|
||||
#
|
||||
# Unless required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
|
||||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
# See the License for the specific language governing permissions and
|
||||
# limitations under the License.
|
||||
|
||||
from . import number_types as N
|
||||
from . import packer
|
||||
from .compat import memoryview_type
|
||||
from .compat import NumpyRequiredForThisFeature, import_numpy
|
||||
|
||||
np = import_numpy()
|
||||
|
||||
FILE_IDENTIFIER_LENGTH = 4
|
||||
|
||||
|
||||
def Get(packer_type, buf, head):
|
||||
"""Get decodes a value at buf[head] using `packer_type`."""
|
||||
return packer_type.unpack_from(memoryview_type(buf), head)[0]
|
||||
|
||||
|
||||
def GetVectorAsNumpy(numpy_type, buf, count, offset):
|
||||
"""GetVecAsNumpy decodes values starting at buf[head] as
|
||||
|
||||
`numpy_type`, where `numpy_type` is a numpy dtype.
|
||||
"""
|
||||
if np is not None:
|
||||
# TODO: could set .flags.writeable = False to make users jump through
|
||||
# hoops before modifying...
|
||||
return np.frombuffer(buf, dtype=numpy_type, count=count, offset=offset)
|
||||
else:
|
||||
raise NumpyRequiredForThisFeature('Numpy was not found.')
|
||||
|
||||
|
||||
def Write(packer_type, buf, head, n):
|
||||
"""Write encodes `n` at buf[head] using `packer_type`."""
|
||||
packer_type.pack_into(buf, head, n)
|
||||
File diff suppressed because it is too large
Load Diff
@@ -0,0 +1,182 @@
|
||||
# Copyright 2014 Google Inc. All rights reserved.
|
||||
#
|
||||
# Licensed under the Apache License, Version 2.0 (the "License");
|
||||
# you may not use this file except in compliance with the License.
|
||||
# You may obtain a copy of the License at
|
||||
#
|
||||
# http://www.apache.org/licenses/LICENSE-2.0
|
||||
#
|
||||
# Unless required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
|
||||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
# See the License for the specific language governing permissions and
|
||||
# limitations under the License.
|
||||
|
||||
import collections
|
||||
import struct
|
||||
|
||||
from . import packer
|
||||
from .compat import NumpyRequiredForThisFeature, import_numpy
|
||||
|
||||
np = import_numpy()
|
||||
|
||||
# For reference, see:
|
||||
# https://docs.python.org/2/library/ctypes.html#ctypes-fundamental-data-types-2
|
||||
|
||||
# These classes could be collections.namedtuple instances, but those are new
|
||||
# in 2.6 and we want to work towards 2.5 compatability.
|
||||
|
||||
|
||||
class BoolFlags(object):
|
||||
bytewidth = 1
|
||||
min_val = False
|
||||
max_val = True
|
||||
py_type = bool
|
||||
name = "bool"
|
||||
packer_type = packer.boolean
|
||||
|
||||
|
||||
class Uint8Flags(object):
|
||||
bytewidth = 1
|
||||
min_val = 0
|
||||
max_val = (2**8) - 1
|
||||
py_type = int
|
||||
name = "uint8"
|
||||
packer_type = packer.uint8
|
||||
|
||||
|
||||
class Uint16Flags(object):
|
||||
bytewidth = 2
|
||||
min_val = 0
|
||||
max_val = (2**16) - 1
|
||||
py_type = int
|
||||
name = "uint16"
|
||||
packer_type = packer.uint16
|
||||
|
||||
|
||||
class Uint32Flags(object):
|
||||
bytewidth = 4
|
||||
min_val = 0
|
||||
max_val = (2**32) - 1
|
||||
py_type = int
|
||||
name = "uint32"
|
||||
packer_type = packer.uint32
|
||||
|
||||
|
||||
class Uint64Flags(object):
|
||||
bytewidth = 8
|
||||
min_val = 0
|
||||
max_val = (2**64) - 1
|
||||
py_type = int
|
||||
name = "uint64"
|
||||
packer_type = packer.uint64
|
||||
|
||||
|
||||
class Int8Flags(object):
|
||||
bytewidth = 1
|
||||
min_val = -(2**7)
|
||||
max_val = (2**7) - 1
|
||||
py_type = int
|
||||
name = "int8"
|
||||
packer_type = packer.int8
|
||||
|
||||
|
||||
class Int16Flags(object):
|
||||
bytewidth = 2
|
||||
min_val = -(2**15)
|
||||
max_val = (2**15) - 1
|
||||
py_type = int
|
||||
name = "int16"
|
||||
packer_type = packer.int16
|
||||
|
||||
|
||||
class Int32Flags(object):
|
||||
bytewidth = 4
|
||||
min_val = -(2**31)
|
||||
max_val = (2**31) - 1
|
||||
py_type = int
|
||||
name = "int32"
|
||||
packer_type = packer.int32
|
||||
|
||||
|
||||
class Int64Flags(object):
|
||||
bytewidth = 8
|
||||
min_val = -(2**63)
|
||||
max_val = (2**63) - 1
|
||||
py_type = int
|
||||
name = "int64"
|
||||
packer_type = packer.int64
|
||||
|
||||
|
||||
class Float32Flags(object):
|
||||
bytewidth = 4
|
||||
min_val = None
|
||||
max_val = None
|
||||
py_type = float
|
||||
name = "float32"
|
||||
packer_type = packer.float32
|
||||
|
||||
|
||||
class Float64Flags(object):
|
||||
bytewidth = 8
|
||||
min_val = None
|
||||
max_val = None
|
||||
py_type = float
|
||||
name = "float64"
|
||||
packer_type = packer.float64
|
||||
|
||||
|
||||
class SOffsetTFlags(Int32Flags):
|
||||
pass
|
||||
|
||||
|
||||
class UOffsetTFlags(Uint32Flags):
|
||||
pass
|
||||
|
||||
|
||||
class VOffsetTFlags(Uint16Flags):
|
||||
pass
|
||||
|
||||
|
||||
def valid_number(n, flags):
|
||||
if flags.min_val is None and flags.max_val is None:
|
||||
return True
|
||||
return flags.min_val <= n <= flags.max_val
|
||||
|
||||
|
||||
def enforce_number(n, flags):
|
||||
if flags.min_val is None and flags.max_val is None:
|
||||
return
|
||||
if not flags.min_val <= n <= flags.max_val:
|
||||
raise TypeError("bad number %s for type %s" % (str(n), flags.name))
|
||||
|
||||
|
||||
def float32_to_uint32(n):
|
||||
packed = struct.pack("<1f", n)
|
||||
(converted,) = struct.unpack("<1L", packed)
|
||||
return converted
|
||||
|
||||
|
||||
def uint32_to_float32(n):
|
||||
packed = struct.pack("<1L", n)
|
||||
(unpacked,) = struct.unpack("<1f", packed)
|
||||
return unpacked
|
||||
|
||||
|
||||
def float64_to_uint64(n):
|
||||
packed = struct.pack("<1d", n)
|
||||
(converted,) = struct.unpack("<1Q", packed)
|
||||
return converted
|
||||
|
||||
|
||||
def uint64_to_float64(n):
|
||||
packed = struct.pack("<1Q", n)
|
||||
(unpacked,) = struct.unpack("<1d", packed)
|
||||
return unpacked
|
||||
|
||||
|
||||
def to_numpy_type(number_type):
|
||||
if np is not None:
|
||||
return np.dtype(number_type.name).newbyteorder("<")
|
||||
else:
|
||||
raise NumpyRequiredForThisFeature("Numpy was not found.")
|
||||
@@ -0,0 +1,41 @@
|
||||
# Copyright 2016 Google Inc. All rights reserved.
|
||||
#
|
||||
# Licensed under the Apache License, Version 2.0 (the "License");
|
||||
# you may not use this file except in compliance with the License.
|
||||
# You may obtain a copy of the License at
|
||||
#
|
||||
# http://www.apache.org/licenses/LICENSE-2.0
|
||||
#
|
||||
# Unless required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
|
||||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
# See the License for the specific language governing permissions and
|
||||
# limitations under the License.
|
||||
|
||||
"""Provide pre-compiled struct packers for encoding and decoding.
|
||||
|
||||
See: https://docs.python.org/2/library/struct.html#format-characters
|
||||
"""
|
||||
|
||||
import struct
|
||||
from . import compat
|
||||
|
||||
|
||||
boolean = struct.Struct(compat.struct_bool_decl)
|
||||
|
||||
uint8 = struct.Struct("<B")
|
||||
uint16 = struct.Struct("<H")
|
||||
uint32 = struct.Struct("<I")
|
||||
uint64 = struct.Struct("<Q")
|
||||
|
||||
int8 = struct.Struct("<b")
|
||||
int16 = struct.Struct("<h")
|
||||
int32 = struct.Struct("<i")
|
||||
int64 = struct.Struct("<q")
|
||||
|
||||
float32 = struct.Struct("<f")
|
||||
float64 = struct.Struct("<d")
|
||||
|
||||
uoffset = uint32
|
||||
soffset = int32
|
||||
voffset = uint16
|
||||
@@ -0,0 +1,148 @@
|
||||
# Copyright 2014 Google Inc. All rights reserved.
|
||||
#
|
||||
# Licensed under the Apache License, Version 2.0 (the "License");
|
||||
# you may not use this file except in compliance with the License.
|
||||
# You may obtain a copy of the License at
|
||||
#
|
||||
# http://www.apache.org/licenses/LICENSE-2.0
|
||||
#
|
||||
# Unless required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
|
||||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
# See the License for the specific language governing permissions and
|
||||
# limitations under the License.
|
||||
|
||||
from . import encode
|
||||
from . import number_types as N
|
||||
|
||||
|
||||
class Table(object):
|
||||
"""Table wraps a byte slice and provides read access to its data.
|
||||
|
||||
The variable `Pos` indicates the root of the FlatBuffers object therein.
|
||||
"""
|
||||
|
||||
__slots__ = ("Bytes", "Pos")
|
||||
|
||||
def __init__(self, buf, pos):
|
||||
N.enforce_number(pos, N.UOffsetTFlags)
|
||||
|
||||
self.Bytes = buf
|
||||
self.Pos = pos
|
||||
|
||||
def Offset(self, vtableOffset):
|
||||
"""Offset provides access into the Table's vtable.
|
||||
|
||||
Deprecated fields are ignored by checking the vtable's length.
|
||||
"""
|
||||
|
||||
vtable = self.Pos - self.Get(N.SOffsetTFlags, self.Pos)
|
||||
vtableEnd = self.Get(N.VOffsetTFlags, vtable)
|
||||
if vtableOffset < vtableEnd:
|
||||
return self.Get(N.VOffsetTFlags, vtable + vtableOffset)
|
||||
return 0
|
||||
|
||||
def Indirect(self, off):
|
||||
"""Indirect retrieves the relative offset stored at `offset`."""
|
||||
N.enforce_number(off, N.UOffsetTFlags)
|
||||
return off + encode.Get(N.UOffsetTFlags.packer_type, self.Bytes, off)
|
||||
|
||||
def String(self, off):
|
||||
"""String gets a string from data stored inside the flatbuffer."""
|
||||
N.enforce_number(off, N.UOffsetTFlags)
|
||||
off += encode.Get(N.UOffsetTFlags.packer_type, self.Bytes, off)
|
||||
start = off + N.UOffsetTFlags.bytewidth
|
||||
length = encode.Get(N.UOffsetTFlags.packer_type, self.Bytes, off)
|
||||
return bytes(self.Bytes[start : start + length])
|
||||
|
||||
def VectorLen(self, off):
|
||||
"""VectorLen retrieves the length of the vector whose offset is stored
|
||||
|
||||
at "off" in this object.
|
||||
"""
|
||||
N.enforce_number(off, N.UOffsetTFlags)
|
||||
|
||||
off += self.Pos
|
||||
off += encode.Get(N.UOffsetTFlags.packer_type, self.Bytes, off)
|
||||
ret = encode.Get(N.UOffsetTFlags.packer_type, self.Bytes, off)
|
||||
return ret
|
||||
|
||||
def Vector(self, off):
|
||||
"""Vector retrieves the start of data of the vector whose offset is
|
||||
|
||||
stored at "off" in this object.
|
||||
"""
|
||||
N.enforce_number(off, N.UOffsetTFlags)
|
||||
|
||||
off += self.Pos
|
||||
x = off + self.Get(N.UOffsetTFlags, off)
|
||||
# data starts after metadata containing the vector length
|
||||
x += N.UOffsetTFlags.bytewidth
|
||||
return x
|
||||
|
||||
def Union(self, t2, off):
|
||||
"""Union initializes any Table-derived type to point to the union at
|
||||
|
||||
the given offset.
|
||||
"""
|
||||
assert type(t2) is Table
|
||||
N.enforce_number(off, N.UOffsetTFlags)
|
||||
|
||||
off += self.Pos
|
||||
t2.Pos = off + self.Get(N.UOffsetTFlags, off)
|
||||
t2.Bytes = self.Bytes
|
||||
|
||||
def Get(self, flags, off):
|
||||
"""Get retrieves a value of the type specified by `flags` at the
|
||||
|
||||
given offset.
|
||||
"""
|
||||
N.enforce_number(off, N.UOffsetTFlags)
|
||||
return flags.py_type(encode.Get(flags.packer_type, self.Bytes, off))
|
||||
|
||||
def GetSlot(self, slot, d, validator_flags):
|
||||
N.enforce_number(slot, N.VOffsetTFlags)
|
||||
if validator_flags is not None:
|
||||
N.enforce_number(d, validator_flags)
|
||||
off = self.Offset(slot)
|
||||
if off == 0:
|
||||
return d
|
||||
return self.Get(validator_flags, self.Pos + off)
|
||||
|
||||
def GetVectorAsNumpy(self, flags, off):
|
||||
"""GetVectorAsNumpy returns the vector that starts at `Vector(off)`
|
||||
|
||||
as a numpy array with the type specified by `flags`. The array is
|
||||
a `view` into Bytes, so modifying the returned array will
|
||||
modify Bytes in place.
|
||||
"""
|
||||
offset = self.Vector(off)
|
||||
length = self.VectorLen(off) # TODO: length accounts for bytewidth, right?
|
||||
numpy_dtype = N.to_numpy_type(flags)
|
||||
return encode.GetVectorAsNumpy(numpy_dtype, self.Bytes, length, offset)
|
||||
|
||||
def GetArrayAsNumpy(self, flags, off, length):
|
||||
"""GetArrayAsNumpy returns the array with fixed width that starts at `Vector(offset)`
|
||||
|
||||
with length `length` as a numpy array with the type specified by `flags`.
|
||||
The
|
||||
array is a `view` into Bytes so modifying the returned will modify Bytes in
|
||||
place.
|
||||
"""
|
||||
numpy_dtype = N.to_numpy_type(flags)
|
||||
return encode.GetVectorAsNumpy(numpy_dtype, self.Bytes, length, off)
|
||||
|
||||
def GetVOffsetTSlot(self, slot, d):
|
||||
"""GetVOffsetTSlot retrieves the VOffsetT that the given vtable location
|
||||
|
||||
points to. If the vtable value is zero, the default value `d`
|
||||
will be returned.
|
||||
"""
|
||||
|
||||
N.enforce_number(slot, N.VOffsetTFlags)
|
||||
N.enforce_number(d, N.VOffsetTFlags)
|
||||
|
||||
off = self.Offset(slot)
|
||||
if off == 0:
|
||||
return d
|
||||
return off
|
||||
@@ -0,0 +1,47 @@
|
||||
# Copyright 2017 Google Inc. All rights reserved.
|
||||
#
|
||||
# Licensed under the Apache License, Version 2.0 (the "License");
|
||||
# you may not use this file except in compliance with the License.
|
||||
# You may obtain a copy of the License at
|
||||
#
|
||||
# http://www.apache.org/licenses/LICENSE-2.0
|
||||
#
|
||||
# Unless required by applicable law or agreed to in writing, software
|
||||
# distributed under the License is distributed on an "AS IS" BASIS,
|
||||
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
# See the License for the specific language governing permissions and
|
||||
# limitations under the License.
|
||||
|
||||
from . import encode
|
||||
from . import number_types
|
||||
from . import packer
|
||||
|
||||
|
||||
def GetSizePrefix(buf, offset):
|
||||
"""Extract the size prefix from a buffer."""
|
||||
return encode.Get(packer.int32, buf, offset)
|
||||
|
||||
|
||||
def GetBufferIdentifier(buf, offset, size_prefixed=False):
|
||||
"""Extract the file_identifier from a buffer"""
|
||||
if size_prefixed:
|
||||
# increase offset by size of UOffsetTFlags
|
||||
offset += number_types.UOffsetTFlags.bytewidth
|
||||
# increase offset by size of root table pointer
|
||||
offset += number_types.UOffsetTFlags.bytewidth
|
||||
# end of FILE_IDENTIFIER
|
||||
end = offset + encode.FILE_IDENTIFIER_LENGTH
|
||||
return buf[offset:end]
|
||||
|
||||
|
||||
def BufferHasIdentifier(buf, offset, file_identifier, size_prefixed=False):
|
||||
got = GetBufferIdentifier(buf, offset, size_prefixed=size_prefixed)
|
||||
return got == file_identifier
|
||||
|
||||
|
||||
def RemoveSizePrefix(buf, offset):
|
||||
"""Create a slice of a size-prefixed buffer that has
|
||||
|
||||
its position advanced just past the size prefix.
|
||||
"""
|
||||
return buf, offset + number_types.Int32Flags.bytewidth
|
||||
Reference in New Issue
Block a user