155 lines
5.7 KiB
Python
155 lines
5.7 KiB
Python
# borrowed from https://github.com/arogozhnikov/einops/blob/master/einops/parsing.py
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import warnings
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import keyword
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from typing import List
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class AnonymousAxis:
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"""Important thing: all instances of this class are not equal to each other"""
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def __init__(self, value: str):
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self.value = int(value)
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if self.value <= 1:
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if self.value == 1:
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raise EinopsError(
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"No need to create anonymous axis of length 1. Report this as an issue"
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)
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else:
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raise EinopsError(
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"Anonymous axis should have positive length, not {}".format(
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self.value
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)
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)
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def __repr__(self):
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return "{}-axis".format(str(self.value))
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class ParsedExpression:
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"""
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non-mutable structure that contains information about one side of expression (e.g. 'b c (h w)')
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and keeps some information important for downstream
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"""
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def __init__(self, expression):
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self.identifiers = set()
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# that's axes like 2, 3 or 5. Axes with size 1 are exceptional and replaced with empty composition
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self.has_non_unitary_anonymous_axes = False
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# composition keeps structure of composite axes, see how different corner cases are handled in tests
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self.composition = []
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if "." in expression:
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raise ValueError("Does not support . in the expression.")
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bracket_group = None
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def add_axis_name(x):
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if x is not None:
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if x in self.identifiers:
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raise ValueError(
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'Indexing expression contains duplicate dimension "{}"'.format(
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x
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)
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)
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is_number = str.isdecimal(x)
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if is_number and int(x) == 1:
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# handling the case of anonymous axis of length 1
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if bracket_group is None:
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self.composition.append([])
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else:
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pass # no need to think about 1s inside parenthesis
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return
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is_axis_name, reason = self.check_axis_name(x, return_reason=True)
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if not (is_number or is_axis_name):
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raise ValueError(
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"Invalid axis identifier: {}\n{}".format(x, reason)
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)
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if is_number:
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x = AnonymousAxis(x)
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self.identifiers.add(x)
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if is_number:
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self.has_non_unitary_anonymous_axes = True
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if bracket_group is None:
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self.composition.append([x])
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else:
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bracket_group.append(x)
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current_identifier = None
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for char in expression:
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if char in "() ":
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add_axis_name(current_identifier)
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current_identifier = None
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if char == "(":
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if bracket_group is not None:
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raise ValueError(
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"Axis composition is one-level (brackets inside brackets not allowed)"
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)
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bracket_group = []
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elif char == ")":
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if bracket_group is None:
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raise ValueError("Brackets are not balanced")
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self.composition.append(bracket_group)
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bracket_group = None
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elif str.isalnum(char) or char == "_":
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if current_identifier is None:
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current_identifier = char
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else:
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current_identifier += char
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else:
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raise ValueError("Unknown character '{}'".format(char))
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if bracket_group is not None:
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raise ValueError(
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'Imbalanced parentheses in expression: "{}"'.format(expression)
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)
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add_axis_name(current_identifier)
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def flat_axes_order(self) -> List:
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result = []
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for composed_axis in self.composition:
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assert isinstance(composed_axis, list), "does not work with ellipsis"
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for axis in composed_axis:
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result.append(axis)
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return result
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def has_composed_axes(self) -> bool:
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# this will ignore 1 inside brackets
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for axes in self.composition:
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if isinstance(axes, list) and len(axes) > 1:
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return True
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return False
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@staticmethod
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def check_axis_name(name: str, return_reason=False):
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"""
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Valid axes names are python identifiers except keywords,
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and additionally should not start or end with underscore
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"""
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if not str.isidentifier(name):
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result = False, "not a valid python identifier"
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elif name[0] == "_" or name[-1] == "_":
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result = False, "axis name should should not start or end with underscore"
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else:
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if keyword.iskeyword(name):
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warnings.warn(
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"It is discouraged to use axes names that are keywords: {}".format(
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name
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),
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RuntimeWarning,
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)
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if name in ["axis"]:
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warnings.warn(
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"It is discouraged to use 'axis' as an axis name "
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"and will raise an error in future",
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FutureWarning,
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)
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result = True, None
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if return_reason:
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return result
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else:
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return result[0]
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def __repr__(self) -> str:
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return "{name}({composition})".format(
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name=self.__class__.__name__, composition=self.composition
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)
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