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from __future__ import annotations
import numbers
import re
from dataclasses import dataclass
from typing import TYPE_CHECKING, Any, Callable
from flexparser import flexparser as fp
from . import common, errors
if TYPE_CHECKING:
from pint import Quantity, UnitsContainer
class ParserHelper:
@classmethod
def from_string(cls, s, *args):
return s
@dataclass(frozen=True)
class _Relation:
_varname_re = re.compile(r"[A-Za-z_][A-Za-z0-9_]*")
src: UnitsContainer
dst: UnitsContainer
equation: str
@classmethod
def _from_string_and_context_sep(
cls, s: str, config: common.Config, separator: str
) -> fp.NullableParsedResult[_Relation]:
if separator not in s:
return None
if ":" not in s:
return None
rel, eq = s.split(":")
parts = rel.split(separator)
try:
src, dst = (config.to_dimension_container(s) for s in parts)
except errors.DefinitionSyntaxError as ex:
return ex
return cls(src, dst, eq.strip())
@property
def variables(self) -> set[str, ...]:
"""Find all variables names in the equation."""
return set(self._varname_re.findall(self.equation))
@property
def transformation(self) -> Callable[..., Quantity[Any]]:
"""Return a transformation callable that uses the registry
to parse the transformation equation.
"""
return lambda ureg, value, **kwargs: ureg.parse_expression(
self.equation, value=value, **kwargs
)
@dataclass(frozen=True)
class ForwardRelation(fp.ParsedStatement, _Relation):
"""A relation connecting a dimension to another via a transformation function.
<source dimension> -> <target dimension>: <transformation function>
"""
@property
def bidirectional(self):
return False
@classmethod
def from_string_and_config(
cls, s: str, config: common.Config
) -> fp.NullableParsedResult[ForwardRelation]:
return super()._from_string_and_context_sep(s, config, "->")
@dataclass(frozen=True)
class BidirectionalRelation(fp.ParsedStatement, _Relation):
"""A bidirectional relation connecting a dimension to another
via a simple transformation function.
<source dimension> <-> <target dimension>: <transformation function>
"""
@property
def bidirectional(self):
return True
@classmethod
def from_string_and_config(
cls, s: str, config: common.Config
) -> fp.NullableParsedResult[BidirectionalRelation]:
return super()._from_string_and_context_sep(s, config, "<->")
@dataclass(frozen=True)
class BeginContext(fp.ParsedStatement):
"""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: common.Config
) -> 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 ex:
return errors.DefinitionSyntaxError(
"Could not parse the Context header", ex
)
if defaults:
# TODO: Use config non_int_type
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 errors.DefinitionSyntaxError(
f"Could not parse Context definition defaults: '{txt}'", exc
)
else:
defaults = {}
return cls(name, tuple(aliases), defaults)
@dataclass(frozen=True)
class ContextDefinition(common.DirectiveBlock):
"""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
"""
@property
def variables(self) -> set[str, ...]:
"""Return all variable names in all transformations."""
return set.union(*(r.variables for r in self.body if isinstance(r, _Relation)))
# TODO: some checks are missing
# @staticmethod
# def parse_definition(line, non_int_type) -> UnitDefinition:
# definition = Definition.from_string(line, non_int_type)
# if not isinstance(definition, UnitDefinition):
# raise DefinitionSyntaxError(
# "Expected <unit> = <converter>; got %s" % line.strip()
# )
# if definition.symbol != definition.name or definition.aliases:
# raise DefinitionSyntaxError(
# "Can't change a unit's symbol or aliases within a context"
# )
# if definition.is_base:
# raise DefinitionSyntaxError("Can't define plain units within a context")
# return definition
# def __post_init__(self):
# missing_pars = self.opening.defaults.keys() - self.variables
# if missing_pars:
# raise DefinitionSyntaxError(
# f"Context parameters {missing_pars} not found in any equation"
# )
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