rdblue commented on a change in pull request #4263: URL: https://github.com/apache/iceberg/pull/4263#discussion_r835541833
########## File path: python/src/iceberg/conversions.py ########## @@ -0,0 +1,294 @@ +# Licensed to the Apache Software Foundation (ASF) under one +# or more contributor license agreements. See the NOTICE file +# distributed with this work for additional information +# regarding copyright ownership. The ASF licenses this file +# to you 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. +"""Utility module for various conversions around PrimitiveType implementations + +This module enables: + - Converting partition strings to built-in python objects + - Converting a value to a byte buffer + - Converting a byte buffer to a value + +Note: + Conversion logic varies based on the PrimitiveType implementation. Therefore conversion functions + are defined here as generic functions using the @singledispatch decorator. For each PrimitiveType + implementation, a concrete function is registered for each generic conversion function. For PrimitiveType + implementations that share the same conversion logic, registrations can be stacked. +""" +import struct +import uuid +from decimal import Decimal, localcontext +from functools import singledispatch +from typing import Union + +from iceberg.types import ( + BinaryType, + BooleanType, + DateType, + DecimalType, + DoubleType, + FixedType, + FloatType, + IntegerType, + LongType, + PrimitiveType, + StringType, + TimestampType, + TimestamptzType, + TimeType, + UUIDType, +) + + +def convert_decimal_to_unscaled_value(decimal_type_var: DecimalType, value: Decimal) -> int: + """Get an unscaled value given a Decimal value and a DecimalType instance with defined precision and scale + + Args: + decimal_type_var (DecimalType): A DecimalType instance with precision and scale + value (Decimal): A Decimal instance + + Raises: + ValueError: If either the scale or precision of `value` does not match that defined in the DecimalType instance provided as `decimal_type_var` + + Returns: + int: The unscaled value + """ + value_as_tuple = value.as_tuple() + value_precision = len(value_as_tuple.digits) + value_scale = -value_as_tuple.exponent + + if value_scale != decimal_type_var.scale: + raise ValueError(f"Cannot serialize value, scale of value does not match type {decimal_type_var}: {value_scale}") + elif value_precision > decimal_type_var.precision: + raise ValueError( + f"Cannot serialize value, precision of value is greater than precision of type {decimal_type_var}: {value_precision}" + ) + + with localcontext() as ctx: + ctx.prec = decimal_type_var.precision + sign, digits, exponent = value.as_tuple() + value_w_adjusted_scale = Decimal((sign, digits, exponent + decimal_type_var.scale)) + return int(value_w_adjusted_scale.to_integral_value()) + + +@singledispatch +def from_partition_value_to_py(primitive_type, partition_value_as_str: str): + """A generic function function which converts a partition string to a python built-in + + Args: + primitive_type(PrimitiveType): An implementation of the PrimitiveType base class + partition_value_as_str(str): A string representation of a partition value + """ + if partition_value_as_str is None: + return None + raise TypeError( + f"Cannot convert partition string to python built-in, type {primitive_type} not supported: '{partition_value_as_str}'" + ) + + +@from_partition_value_to_py.register(BooleanType) +def _(primitive_type, partition_value_as_str: str): + if partition_value_as_str is None: + return None Review comment: Instead of adding this check in every method, could we use an outer function that calls the `@singledispatch` method? ```python def partition_to_py(primitive_type: PrimitiveType, value_str: str): if value_str is None: return None elif value_str == '__HIVE_DEFAULT_PARTITION__': return None return _partition_to_py(primitive_type, value_str) @singledispatch def _partition_to_py(primitive_type: PrimitiveType, value_str: str): raise TypeError("Cannot convert '{value_str}' to unsupported type: {primitive_type}") ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
