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"""
pint.delegates.txt_defparser.context
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Definitions for parsing Context and their related objects
Notices that some of the checks are done within the
format agnostic parent definition class.
See each one for a slighly longer description of the
syntax.
:copyright: 2022 by Pint Authors, see AUTHORS for more details.
:license: BSD, see LICENSE for more details.
"""
from __future__ import annotations
import numbers
import re
import typing as ty
from dataclasses import dataclass
from typing import Union
import flexparser as fp
from ...facets.context import definitions
from ..base_defparser import ParserConfig, PintParsedStatement
from . import block, common, plain
# TODO check syntax
T = ty.TypeVar("T", bound="Union[ForwardRelation, BidirectionalRelation]")
def _from_string_and_context_sep(
cls: type[T], s: str, config: ParserConfig, separator: str
) -> T | None:
if separator not in s:
return None
if ":" not in s:
return None
rel, eq = s.split(":")
parts = rel.split(separator)
src, dst = (config.to_dimension_container(s) for s in parts)
return cls(src, dst, eq.strip())
@dataclass(frozen=True)
class ForwardRelation(PintParsedStatement, definitions.ForwardRelation):
"""A relation connecting a dimension to another via a transformation function.
<source dimension> -> <target dimension>: <transformation function>
"""
@classmethod
def from_string_and_config(
cls, s: str, config: ParserConfig
) -> fp.NullableParsedResult[ForwardRelation]:
return _from_string_and_context_sep(cls, s, config, "->")
@dataclass(frozen=True)
class BidirectionalRelation(PintParsedStatement, definitions.BidirectionalRelation):
"""A bidirectional relation connecting a dimension to another
via a simple transformation function.
<source dimension> <-> <target dimension>: <transformation function>
"""
@classmethod
def from_string_and_config(
cls, s: str, config: ParserConfig
) -> fp.NullableParsedResult[BidirectionalRelation]:
return _from_string_and_context_sep(cls, s, config, "<->")
@dataclass(frozen=True)
class BeginContext(PintParsedStatement):
"""Being of a context directive.
@context[(defaults)] <canonical name> [= <alias>] [= <alias>]
"""
_header_re = re.compile(
r"@context\s*(?P<defaults>\(.*\))?\s+(?P<name>\w+)\s*(=(?P<aliases>.*))*"
)
name: str
aliases: tuple[str, ...]
defaults: dict[str, numbers.Number]
@classmethod
def from_string_and_config(
cls, s: str, config: ParserConfig
) -> fp.NullableParsedResult[BeginContext]:
try:
r = cls._header_re.search(s)
if r is None:
return None
name = r.groupdict()["name"].strip()
aliases = r.groupdict()["aliases"]
if aliases:
aliases = tuple(a.strip() for a in r.groupdict()["aliases"].split("="))
else:
aliases = ()
defaults = r.groupdict()["defaults"]
except Exception as exc:
return common.DefinitionSyntaxError(
f"Could not parse the Context header '{s}': {exc}"
)
if defaults:
txt = defaults
try:
defaults = (part.split("=") for part in defaults.strip("()").split(","))
defaults = {str(k).strip(): config.to_number(v) for k, v in defaults}
except (ValueError, TypeError) as exc:
return common.DefinitionSyntaxError(
f"Could not parse Context definition defaults '{txt}' {exc}"
)
else:
defaults = {}
return cls(name, tuple(aliases), defaults)
@dataclass(frozen=True)
class ContextDefinition(
block.DirectiveBlock[
definitions.ContextDefinition,
BeginContext,
ty.Union[
plain.CommentDefinition,
BidirectionalRelation,
ForwardRelation,
plain.UnitDefinition,
],
]
):
"""Definition of a Context
@context[(defaults)] <canonical name> [= <alias>] [= <alias>]
# units can be redefined within the context
<redefined unit> = <relation to another unit>
# can establish unidirectional relationships between dimensions
<dimension 1> -> <dimension 2>: <transformation function>
# can establish bidirectionl relationships between dimensions
<dimension 3> <-> <dimension 4>: <transformation function>
@end
See BeginContext, Equality, ForwardRelation, BidirectionalRelation and
Comment for more parsing related information.
Example::
@context(n=1) spectroscopy = sp
# n index of refraction of the medium.
[length] <-> [frequency]: speed_of_light / n / value
[frequency] -> [energy]: planck_constant * value
[energy] -> [frequency]: value / planck_constant
# allow wavenumber / kayser
[wavenumber] <-> [length]: 1 / value
@end
"""
def derive_definition(self) -> definitions.ContextDefinition:
return definitions.ContextDefinition(
self.name, self.aliases, self.defaults, self.relations, self.redefinitions
)
@property
def name(self) -> str:
assert isinstance(self.opening, BeginContext)
return self.opening.name
@property
def aliases(self) -> tuple[str, ...]:
assert isinstance(self.opening, BeginContext)
return self.opening.aliases
@property
def defaults(self) -> dict[str, numbers.Number]:
assert isinstance(self.opening, BeginContext)
return self.opening.defaults
@property
def relations(self) -> tuple[BidirectionalRelation | ForwardRelation, ...]:
return tuple(
r
for r in self.body
if isinstance(r, (ForwardRelation, BidirectionalRelation))
)
@property
def redefinitions(self) -> tuple[plain.UnitDefinition, ...]:
return tuple(r for r in self.body if isinstance(r, plain.UnitDefinition))
|
