from enum import Enum, auto
from typing import NamedTuple
from position import Span


class TokenType(Enum):
    Eof = auto()
    InvalidChar = auto()
    MalformedComment = auto()
    MalformedChar = auto()
    MalformedString = auto()
    Id = auto()
    Int = auto()
    Char = auto()
    String = auto()
    LParen = auto()
    RParen = auto()
    LBrace = auto()
    RBrace = auto()
    LBracket = auto()
    RBracket = auto()
    Underscore = auto()
    Dot = auto()
    DotDot = auto()
    DotDotDot = auto()
    DotDotEqual = auto()
    Comma = auto()
    Colon = auto()
    ColonColon = auto()
    ColonColonLT = auto()
    Semicolon = auto()
    Ampersand = auto()
    Plus = auto()
    PlusEqual = auto()
    Minus = auto()
    MinusEqual = auto()
    MinusLT = auto()
    Asterisk = auto()
    AsteriskEqual = auto()
    AsteriskAsterisk = auto()
    Slash = auto()
    SlashEqual = auto()
    Percent = auto()
    PercentEqual = auto()
    Equal = auto()
    EqualEqual = auto()
    EqualLT = auto()
    Exclamation = auto()
    ExclamationEqual = auto()
    LT = auto()
    LTEqual = auto()
    GT = auto()
    GTEqual = auto()
    KwFalse = auto()
    KwTrue = auto()
    KwNot = auto()
    KwIn = auto()
    KwAnd = auto()
    KwOr = auto()
    KwXor = auto()
    KwLet = auto()
    KwMut = auto()
    KwIf = auto()
    KwMatch = auto()
    KwElse = auto()
    KwLoop = auto()
    KwWhile = auto()
    KwFor = auto()
    KwBreak = auto()
    KwContinue = auto()
    KwFn = auto()
    KwReturn = auto()


class Token(NamedTuple):
    token_type: TokenType
    index: int
    length: int
    span: Span

    def text_slice(self, text: str) -> str:
        return text[self.index:self.index + self.length]


class TokenIterator:
    def next(self) -> Token:
        raise NotImplementedError()