nonebot2/nonebot/adapters/_formatter.py
2021-08-28 19:42:32 +08:00

109 lines
3.9 KiB
Python

import functools
import operator
from string import Formatter
from typing import (Any, Set, List, Type, Tuple, Union, TypeVar, Mapping,
Generic, Sequence, TYPE_CHECKING)
if TYPE_CHECKING:
from . import Message
TM = TypeVar("TM", bound="Message")
class MessageFormatter(Formatter, Generic[TM]):
"""消息模板格式化实现类"""
def __init__(self, factory: Type[TM], template: str) -> None:
self.template = template
self.factory = factory
def format(self, *args: Any, **kwargs: Any) -> TM:
"""
:说明:
根据模板和参数生成消息对象
"""
msg = self.vformat(self.template, args, kwargs)
return msg if isinstance(msg, self.factory) else self.factory(msg)
def vformat(self, format_string: str, args: Sequence[Any],
kwargs: Mapping[str, Any]) -> TM:
used_args = set()
result, _ = self._vformat(format_string, args, kwargs, used_args, 2)
self.check_unused_args(list(used_args), args, kwargs)
return result
def _vformat(
self,
format_string: str,
args: Sequence[Any],
kwargs: Mapping[str, Any],
used_args: Set[Union[int, str]],
recursion_depth: int,
auto_arg_index: int = 0,
) -> Tuple[TM, int]:
if recursion_depth < 0:
raise ValueError("Max string recursion exceeded")
results: List[Any] = []
for (literal_text, field_name, format_spec,
conversion) in self.parse(format_string):
# output the literal text
if literal_text:
results.append(literal_text)
# if there's a field, output it
if field_name is not None:
# this is some markup, find the object and do
# the formatting
# handle arg indexing when empty field_names are given.
if field_name == "":
if auto_arg_index is False:
raise ValueError(
"cannot switch from manual field specification to "
"automatic field numbering")
field_name = str(auto_arg_index)
auto_arg_index += 1
elif field_name.isdigit():
if auto_arg_index:
raise ValueError(
"cannot switch from manual field specification to "
"automatic field numbering")
# disable auto arg incrementing, if it gets
# used later on, then an exception will be raised
auto_arg_index = False
# given the field_name, find the object it references
# and the argument it came from
obj, arg_used = self.get_field(field_name, args, kwargs)
used_args.add(arg_used)
assert format_spec is not None
# do any conversion on the resulting object
obj = self.convert_field(obj, conversion) if conversion else obj
# expand the format spec, if needed
format_control, auto_arg_index = self._vformat(
format_spec,
args,
kwargs,
used_args,
recursion_depth - 1,
auto_arg_index,
)
# format the object and append to the result
formatted_text = self.format_field(obj, str(format_control))
results.append(formatted_text)
return self.factory(functools.reduce(operator.add, results or
[""])), auto_arg_index
def format_field(self, value: Any, format_spec: str) -> Any:
return super().format_field(value, format_spec) if format_spec else value