57 lines
1.7 KiB
Python
57 lines
1.7 KiB
Python
import dataclasses
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import random
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import re
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from typing import Self
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from roll.throw import Throw
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MIN_SIDES = 2
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ROLL_PATTERN = re.compile(r"(\d+)d(\d+)([+-]\d+)?")
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@dataclasses.dataclass(frozen=True)
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class Roll:
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"""a roll of one or more dice"""
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dice_count: int = 1
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sides: int = 20
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modifier: int = 0
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def __post_init__(self) -> None:
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if self.dice_count < 1:
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msg = "dice must be greater than 0"
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raise ValueError(msg)
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if self.sides < MIN_SIDES:
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msg = "sides must be greater than 1"
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raise ValueError(msg)
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@classmethod
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def from_str(cls, value: str) -> Self:
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"""parse a Roll from its short representation, e.g. 2d6 or 1d20-2"""
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match = ROLL_PATTERN.fullmatch(value)
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if match is None:
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msg = f"expected {value!r} to match pattern {ROLL_PATTERN.pattern!r}"
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raise ValueError(msg)
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dice_count, sides, modifier = match.groups()
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return cls(int(dice_count), int(sides), int(modifier) if modifier else 0)
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def modifier_str(self) -> str:
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"""return the modifier as a string"""
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if self.modifier == 0:
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return ""
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return f"{self.modifier:+}"
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def to_str(self) -> str:
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"""return the short representation of a roll, e.g. 3d4 or 2d20+3"""
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return f"{self.dice_count}d{self.sides}{self.modifier_str()}"
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def modify(self, modifier: int) -> Self:
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"""return a new Roll with the given modifier"""
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return dataclasses.replace(self, modifier=modifier)
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def throw(self) -> Throw:
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"""throw the dice"""
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throw = [random.randint(1, self.sides) for _ in range(self.dice_count)]
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return Throw(throw, self.sides, self.modifier)
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