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"""
pint.facets.group.defintions
~~~~~~~~~~~~~~~~~~~~~~~~~~~~
:copyright: 2022 by Pint Authors, see AUTHORS for more details.
:license: BSD, see LICENSE for more details.
"""
from __future__ import annotations
import re
from dataclasses import dataclass
from typing import Tuple
from ...definitions import Definition
from ...errors import DefinitionSyntaxError
from ...util import SourceIterator
from ..plain.definitions import UnitDefinition
@dataclass(frozen=True)
class GroupDefinition:
"""Definition of a group.
@group <name> [using <group 1>, ..., <group N>]
<definition 1>
...
<definition N>
@end
Example::
@group AvoirdupoisUS using Avoirdupois
US_hundredweight = hundredweight = US_cwt
US_ton = ton
US_force_ton = force_ton = _ = US_ton_force
@end
"""
#: Regex to match the header parts of a definition.
_header_re = re.compile(r"@group\s+(?P<name>\w+)\s*(using\s(?P<used_groups>.*))*")
name: str
units: Tuple[Tuple[int, UnitDefinition], ...]
using_group_names: Tuple[str, ...]
@property
def unit_names(self) -> Tuple[str, ...]:
return tuple(u.name for lineno, u in self.units)
@classmethod
def from_lines(cls, lines, non_int_type=float):
"""Return a Group object parsing an iterable of lines.
Parameters
----------
lines : list[str]
iterable
define_func : callable
Function to define a unit in the registry; it must accept a single string as
a parameter.
Returns
-------
"""
lines = SourceIterator(lines)
lineno, header = next(lines)
r = cls._header_re.search(header)
if r is None:
raise ValueError("Invalid Group header syntax: '%s'" % header)
name = r.groupdict()["name"].strip()
groups = r.groupdict()["used_groups"]
if groups:
parent_group_names = tuple(a.strip() for a in groups.split(","))
else:
parent_group_names = ()
units = []
for lineno, line in lines:
definition = Definition.from_string(line, non_int_type=non_int_type)
if not isinstance(definition, UnitDefinition):
raise DefinitionSyntaxError(
"Only UnitDefinition are valid inside _used_groups, not "
+ str(definition),
lineno=lineno,
)
units.append((lineno, definition))
return cls(name, tuple(units), parent_group_names)
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