rlp package

Subpackages

• rlp.sedes package
  • Submodules
  • rlp.sedes.big_endian_int module
  • rlp.sedes.binary module
  • rlp.sedes.boolean module
  • rlp.sedes.lists module
    • CountableList
      • CountableList.deserialize()
      • CountableList.serialize()
    • List
      • List.deserialize()
      • List.serialize()
    • is_sedes()
    • is_sequence()
  • rlp.sedes.raw module
  • rlp.sedes.serializable module
    • BaseChangeset
      • BaseChangeset.build_rlp()
      • BaseChangeset.close()
      • BaseChangeset.commit()
      • BaseChangeset.open()
    • BaseSerializable
      • BaseSerializable.as_dict()
      • BaseSerializable.build_changeset()
      • BaseSerializable.copy()
      • BaseSerializable.deserialize()
      • BaseSerializable.serialize()
    • Changeset()
    • ChangesetField
      • ChangesetField.field
    • ChangesetState
      • ChangesetState.CLOSED
      • ChangesetState.INITIALIZED
      • ChangesetState.OPEN
    • MetaBase
      • MetaBase.field_attrs
      • MetaBase.field_names
      • MetaBase.fields
      • MetaBase.sedes
    • Serializable
    • SerializableBase
    • make_immutable()
    • merge_args_to_kwargs()
    • merge_kwargs_to_args()
    • validate_args_and_kwargs()
  • rlp.sedes.text module
  • Module contents

Submodules

rlp.atomic module

class rlp.atomic.Atomic

Bases: object

ABC for objects that can be RLP encoded as is.

rlp.codec module

rlp.codec.consume_item(rlp, start)

Read an item from an RLP string.

Parameters:

• rlp – the rlp string to read from

• start – the position at which to start reading

Returns:

a tuple (item, per_item_rlp, end), where item is the read item, per_item_rlp is a list containing the RLP encoding of each item and end is the position of the first unprocessed byte

rlp.codec.consume_length_prefix(rlp, start)

Read a length prefix from an RLP string.

Parameters:

• rlp – the rlp byte string to read from

• start – the position at which to start reading

Returns:

a tuple (prefix, type, length, end), where type is either str or list depending on the type of the following payload, length is the length of the payload in bytes, and end is the position of the first payload byte in the rlp string

rlp.codec.consume_payload(rlp, prefix, start, type_, length)

Read the payload of an item from an RLP string.

Parameters:

• rlp – the rlp string to read from

• type – the type of the payload (bytes or list)

• start – the position at which to start reading

• length – the length of the payload in bytes

Returns:

a tuple (item, per_item_rlp, end), where item is the read item, per_item_rlp is a list containing the RLP encoding of each item and end is the position of the first unprocessed byte

rlp.codec.decode(rlp, sedes=None, strict=True, recursive_cache=False, **kwargs)

Decode an RLP encoded object.

If the deserialized result obj has an attribute _cached_rlp (e.g. if sedes is a subclass of rlp.Serializable) it will be set to rlp, which will improve performance on subsequent rlp.encode() calls. Bear in mind however that obj needs to make sure that this value is updated whenever one of its fields changes or prevent such changes entirely (rlp.sedes.Serializable does the latter).

Parameters:

• sedes – an object implementing a function deserialize(code) which will be applied after decoding, or None if no deserialization should be performed

• **kwargs – additional keyword arguments that will be passed to the deserializer

• strict – if false inputs that are longer than necessary don’t cause an exception

Returns:

the decoded and maybe deserialized Python object

Raises:

rlp.DecodingError if the input string does not end after the root item and strict is true

Raises:

rlp.DeserializationError if the deserialization fails

rlp.codec.decode_raw(item, strict, _)

rlp.codec.encode(obj, sedes=None, infer_serializer=True, cache=True)

Encode a Python object in RLP format.

By default, the object is serialized in a suitable way first (using rlp.infer_sedes()) and then encoded. Serialization can be explicitly suppressed by setting infer_serializer to False and not passing an alternative as sedes.

If obj has an attribute _cached_rlp (as, notably, rlp.Serializable) and its value is not None, this value is returned bypassing serialization and encoding, unless sedes is given (as the cache is assumed to refer to the standard serialization which can be replaced by specifying sedes).

If obj is a rlp.Serializable and cache is true, the result of the encoding will be stored in _cached_rlp if it is empty.

Parameters:

• sedes – an object implementing a function serialize(obj) which will be used to serialize obj before encoding, or None to use the infered one (if any)

• infer_serializer – if True an appropriate serializer will be selected using rlp.infer_sedes() to serialize obj before encoding

• cache – cache the return value in obj._cached_rlp if possible (default True)

Returns:

the RLP encoded item

Raises:

rlp.EncodingError in the rather unlikely case that the item is too big to encode (will not happen)

Raises:

rlp.SerializationError if the serialization fails

rlp.codec.encode_raw(item)

RLP encode (a nested sequence of) Atomics.

rlp.codec.infer_sedes(obj)

Try to find a sedes objects suitable for a given Python object.

The sedes objects considered are obj’s class, big_endian_int and binary. If obj is a sequence, a rlp.sedes.List will be constructed recursively.

Parameters:

obj – the python object for which to find a sedes object

Raises:

TypeError if no appropriate sedes could be found

rlp.codec.length_prefix(length, offset)

Construct the prefix to lists or strings denoting their length.

Parameters:

• length – the length of the item in bytes

• offset – 0x80 when encoding raw bytes, 0xc0 when encoding a list

rlp.exceptions module

exception rlp.exceptions.DecodingError(message, rlp)

Bases: RLPException

Exception raised if decoding fails.

Variables:

rlp – the RLP string that could not be decoded

exception rlp.exceptions.DeserializationError(message, serial)

Bases: RLPException

Exception raised if deserialization fails.

Variables:

serial – the decoded RLP string that could not be deserialized

exception rlp.exceptions.EncodingError(message, obj)

Bases: RLPException

Exception raised if encoding fails.

Variables:

obj – the object that could not be encoded

exception rlp.exceptions.ListDeserializationError(message=None, serial=None, element_exception=None, index=None)

Bases: DeserializationError

Exception raised if deserialization by a sedes.List fails.

Variables:

• element_exception – the exception that occurred during the deserialization of one of the elements, or None if the error is unrelated to a specific element

• index – the index in the list that produced the error or None if the error is unrelated to a specific element

exception rlp.exceptions.ListSerializationError(message=None, obj=None, element_exception=None, index=None)

Bases: SerializationError

Exception raised if serialization by a sedes.List fails.

Variables:

• element_exception – the exception that occurred during the serialization of one of the elements, or None if the error is unrelated to a specific element

• index – the index in the list that produced the error or None if the error is unrelated to a specific element

exception rlp.exceptions.ObjectDeserializationError(message=None, serial=None, sedes=None, list_exception=None)

Bases: DeserializationError

Exception raised if deserialization by a sedes.Serializable fails.

Variables:

• sedes – the sedes.Serializable that failed

• list_exception – exception raised by the underlying list sedes, or None if no such exception has been raised

• field – name of the field of the object that produced the error, or None if no field responsible for the error

exception rlp.exceptions.ObjectSerializationError(message=None, obj=None, sedes=None, list_exception=None)

Bases: SerializationError

Exception raised if serialization of a sedes.Serializable object fails.

Variables:

• sedes – the sedes.Serializable that failed

• list_exception – exception raised by the underlying list sedes, or None if no such exception has been raised

• field – name of the field of the object that produced the error, or None if no field responsible for the error

exception rlp.exceptions.RLPException

Bases: Exception

Base class for exceptions raised by this package.

exception rlp.exceptions.SerializationError(message, obj)

Bases: RLPException

Exception raised if serialization fails.

Variables:

obj – the object that could not be serialized

rlp.lazy module

class rlp.lazy.LazyList(rlp, start, end, sedes=None, **sedes_kwargs)

Bases: Sequence

A RLP encoded list which decodes itself when necessary.

Both indexing with positive indices and iterating are supported. Getting the length with len() is possible as well but requires full horizontal encoding.

Parameters:

• rlp – the rlp string in which the list is encoded

• start – the position of the first payload byte of the encoded list

• end – the position of the last payload byte of the encoded list

• sedes – a sedes object which deserializes each element of the list, or None for no deserialization

• **sedes_kwargs – keyword arguments which will be passed on to the deserializer

next()

rlp.lazy.consume_item_lazy(rlp, start)

Read an item from an RLP string lazily.

If the length prefix announces a string, the string is read; if it announces a list, a LazyList is created.

Parameters:

• rlp – the rlp string to read from

• start – the position at which to start reading

Returns:

a tuple (item, end) where item is the read string or a LazyList and end is the position of the first unprocessed byte.

rlp.lazy.decode_lazy(rlp, sedes=None, **sedes_kwargs)

Decode an RLP encoded object in a lazy fashion.

If the encoded object is a bytestring, this function acts similar to rlp.decode(). If it is a list however, a LazyList is returned instead. This object will decode the string lazily, avoiding both horizontal and vertical traversing as much as possible.

The way sedes is applied depends on the decoded object: If it is a string sedes deserializes it as a whole; if it is a list, each element is deserialized individually. In both cases, sedes_kwargs are passed on. Note that, if a deserializer is used, only “horizontal” but not “vertical lazyness” can be preserved.

Parameters:

• rlp – the RLP string to decode

• sedes – an object implementing a method deserialize(code) which is used as described above, or None if no deserialization should be performed

• **sedes_kwargs – additional keyword arguments that will be passed to the deserializers

Returns:

either the already decoded and deserialized object (if encoded as a string) or an instance of rlp.LazyList

rlp.lazy.peek(rlp, index, sedes=None)

Get a specific element from an rlp encoded nested list.

This function uses rlp.decode_lazy() and, thus, decodes only the necessary parts of the string.

Usage example:

>>> import rlp
>>> rlpdata = rlp.encode([1, 2, [3, [4, 5]]])
>>> rlp.peek(rlpdata, 0, rlp.sedes.big_endian_int)
1
>>> rlp.peek(rlpdata, [2, 0], rlp.sedes.big_endian_int)
3

Parameters:

• rlp – the rlp string

• index – the index of the element to peek at (can be a list for nested data)

• sedes – a sedes used to deserialize the peeked at object, or None if no deserialization should be performed

Raises:

IndexError if index is invalid (out of range or too many levels)

rlp.utils module

Module contents