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Improves typing in Hash classes #146

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d570080
Fixes hash
tedkalaw Mar 9, 2021
b4df56c
Fixes initializer
tedkalaw Mar 9, 2021
b4c7409
Removes _LENGTH
tedkalaw Mar 9, 2021
55d1fbd
Moves more functionality into base class
tedkalaw Mar 9, 2021
2cddeef
Use abstractmethod instead of abstractclassmethod
tedkalaw Mar 9, 2021
04f5d7f
Removes extraneous const
tedkalaw Mar 9, 2021
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66 changes: 54 additions & 12 deletions xrpl/binarycodec/types/hash.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,10 +3,10 @@
"""
from __future__ import annotations # Requires Python 3.7+

from abc import ABC

from typing_extensions import Final
from abc import ABC, abstractmethod
from typing import Optional, Type

from xrpl.binarycodec.binary_wrappers.binary_parser import BinaryParser
from xrpl.binarycodec.exceptions import XRPLBinaryCodecException
from xrpl.binarycodec.types.serialized_type import SerializedType

Expand All @@ -15,24 +15,66 @@ class Hash(SerializedType, ABC):
"""
Base class for XRPL Hash types.
`See Hash Fields <https://xrpl.org/serialization.html#hash-fields>`_

Attributes:
_LENGTH: The length of this hash in bytes.
"""

_LENGTH: Final[int]

def __init__(self: Hash, buffer: bytes) -> None:
def __init__(self: Hash, buffer: Optional[bytes]) -> None:
"""
Construct a Hash.

:param buffer: The byte buffer that will be used to store
the serialized encoding of this field.
Args:
buffer: The byte buffer that will be used to store the serialized
encoding of this field.
"""
if len(buffer) != self._LENGTH:
buffer = buffer if buffer is not None else bytes(self._get_length())

if len(buffer) != self._get_length():
raise XRPLBinaryCodecException("Invalid hash length {}".format(len(buffer)))
super().__init__(buffer)

def __str__(self: Hash) -> str:
"""Returns a hex-encoded string representation of the bytes buffer."""
return self.to_hex()

@classmethod
def from_value(cls: Type[Hash], value: str) -> Hash:
"""
Construct a Hash object from a hex string.

Args:
value: The value to construct a Hash from.

Returns:
The Hash object constructed from value.

Raises:
XRPLBinaryCodecException: If the supplied value is of the wrong type.
"""
if not isinstance(value, str):
raise XRPLBinaryCodecException(
"Invalid type to construct a {}: expected str,"
" received {}.".format(cls.__name__, value.__class__.__name__)
)

return cls(bytes.fromhex(value))

@classmethod
def from_parser(
cls: Type[Hash], parser: BinaryParser, length_hint: Optional[int] = None
) -> Hash:
"""
Construct a Hash object from an existing BinaryParser.

Args:
parser: The parser to construct the Hash object from.
length_hint: The number of bytes to consume from the parser.

Returns:
The Hash object constructed from a parser.
"""
num_bytes = length_hint if length_hint is not None else cls._get_length()
return cls(parser.read(num_bytes))

@classmethod
@abstractmethod
def _get_length(cls: Type[Hash]) -> int:
raise NotImplementedError("Hash._get_length not implemented")
Comment on lines +79 to +80
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a better way to do this would probably use some combination of @property, @abstractmethod, and @classmethod, so that the base class implements an abstract getter for a class property and the subclasses can just use the length = 20 syntax

unfortunately, this isn't officially supported by mypy: python/mypy#8532
as such, i went with using a non-property getter. let me know what you think

54 changes: 3 additions & 51 deletions xrpl/binarycodec/types/hash128.py
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Expand Up @@ -5,10 +5,8 @@
"""
from __future__ import annotations

from typing import Optional
from typing import Type

from xrpl.binarycodec import XRPLBinaryCodecException
from xrpl.binarycodec.binary_wrappers.binary_parser import BinaryParser
from xrpl.binarycodec.types.hash import Hash


Expand All @@ -17,54 +15,8 @@ class Hash128(Hash):
Codec for serializing and deserializing a hash field with a width
of 128 bits (16 bytes).
`See Hash Fields <https://xrpl.org/serialization.html#hash-fields>`_


Attributes:
_LENGTH: The length of this hash in bytes.
"""

_LENGTH = 16

def __init__(self: Hash128, buffer: bytes = None) -> None:
"""Construct a Hash128."""
buffer = buffer if buffer is not None else bytes(self._LENGTH)
super().__init__(buffer)

@classmethod
def from_value(cls: Hash128, value: str) -> Hash128:
"""
Construct a Hash128 object from a hex string.

Args:
value: The value to construct a Hash128 from.

Returns:
The Hash128 object constructed from value.

Raises:
XRPLBinaryCodecException: If the supplied value is of the wrong type.
"""
if not isinstance(value, str):
raise XRPLBinaryCodecException(
"Invalid type to construct a Hash128: expected str,"
" received {}.".format(value.__class__.__name__)
)

return cls(bytes.fromhex(value))

@classmethod
def from_parser(
cls: Hash128, parser: BinaryParser, length_hint: Optional[int] = None
) -> Hash128:
"""
Construct a Hash128 object from an existing BinaryParser.

Args:
parser: The parser to construct the Hash128 object from.
length_hint: The number of bytes to consume from the parser.

Returns:
The Hash128 object constructed from a parser.
"""
num_bytes = length_hint if length_hint is not None else cls._LENGTH
return cls(parser.read(num_bytes))
def _get_length(cls: Type[Hash128]) -> int:
return 16
54 changes: 3 additions & 51 deletions xrpl/binarycodec/types/hash160.py
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Expand Up @@ -4,10 +4,8 @@
"""
from __future__ import annotations

from typing import Optional, Type
from typing import Type

from xrpl.binarycodec import XRPLBinaryCodecException
from xrpl.binarycodec.binary_wrappers.binary_parser import BinaryParser
from xrpl.binarycodec.types.hash import Hash


Expand All @@ -16,54 +14,8 @@ class Hash160(Hash):
Codec for serializing and deserializing a hash field with a width
of 160 bits (20 bytes).
`See Hash Fields <https://xrpl.org/serialization.html#hash-fields>`_


Attributes:
_LENGTH: The length of this hash in bytes.
"""

_LENGTH = 20

def __init__(self: Hash160, buffer: bytes = None) -> None:
"""Construct a Hash160."""
buffer = buffer if buffer is not None else bytes(self._width)
super().__init__(buffer)

@classmethod
def from_value(cls: Hash160, value: str) -> Hash160:
"""
Construct a Hash160 object from a hex string.

Args:
value: The string to construct a Hash160 from.

Returns:
The Hash160 constructed from value.

Raises:
XRPLBinaryCodecException: If the supplied value is of the wrong type.
"""
if not isinstance(value, str):
raise XRPLBinaryCodecException(
"Invalid type to construct a Hash160: expected str,"
" received {}.".format(value.__class__.__name__)
)

return cls(bytes.fromhex(value))

@classmethod
def from_parser(
cls: Type[Hash160], parser: BinaryParser, length_hint: Optional[int] = None
) -> Hash160:
"""
Construct a Hash160 object from an existing BinaryParser.

Args:
parser: The parser to construct Hash160 from.
length_hint: The number of bytes to consume from the parser.

Returns:
The Hash160 constructed from the parser.
"""
num_bytes = length_hint if length_hint is not None else cls._LENGTH
return cls(parser.read(num_bytes))
def _get_length(cls: Type[Hash160]) -> int:
return 20
53 changes: 3 additions & 50 deletions xrpl/binarycodec/types/hash256.py
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Original file line number Diff line number Diff line change
Expand Up @@ -5,10 +5,8 @@
"""
from __future__ import annotations

from typing import Optional
from typing import Type

from xrpl.binarycodec import XRPLBinaryCodecException
from xrpl.binarycodec.binary_wrappers.binary_parser import BinaryParser
from xrpl.binarycodec.types.hash import Hash


Expand All @@ -17,53 +15,8 @@ class Hash256(Hash):
Codec for serializing and deserializing a hash field with a width
of 256 bits (32 bytes).
`See Hash Fields <https://xrpl.org/serialization.html#hash-fields>`_


Attributes:
: The length of this hash in bytes.
"""

_LENGTH = 32

def __init__(self: Hash256, buffer: bytes = None) -> None:
"""Construct a Hash256."""
buffer = buffer if buffer is not None else bytes(self._width)
super().__init__(buffer)

@classmethod
def from_value(cls: Hash256, value: str) -> Hash256:
"""
Construct a Hash256 object from a hex string.

Args:
value: The string to construct a Hash256 object from.

Returns:
The Hash256 constructed from value.

Raises:
XRPLBinaryCodecException: If the supplied value is of the wrong type.
"""
if not isinstance(value, str):
raise XRPLBinaryCodecException(
"Invalid type to construct a Hash256: expected str,"
" received {}.".format(value.__class__.__name__)
)
return cls(bytes.fromhex(value))

@classmethod
def from_parser(
cls: Hash256, parser: BinaryParser, length_hint: Optional[int] = None
) -> Hash256:
"""
Construct a Hash256 object from an existing BinaryParser.

Args:
parser: The parser to construct a Hash256 from.
length_hint: The number of bytes to consume from the parser.

Returns:
The Hash256 constructed from parser.
"""
num_bytes = length_hint if length_hint is not None else cls._LENGTH
return cls(parser.read(num_bytes))
def _get_length(cls: Type[Hash256]) -> int:
return 32