Mirror Chain

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class MIR20:
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    DECIMALS = 6
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    TOTAL_UNITS = 1_000_000_000 * (10 ** DECIMALS)
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    def __init__(self, deployer):
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        self.name = "MIR-20"
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        self.symbol = "MIR"
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        self.decimals = self.DECIMALS
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        # fixed supply
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        self._total_supply = self.TOTAL_UNITS
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        # assign entire supply to deployer
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        self._balances = {deployer: self.TOTAL_UNITS}
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    # ---------- Views ----------
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    def totalSupply(self):
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        return self._total_supply  # in smallest units
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    def balanceOf(self, account):
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        return self._balances.get(account, 0)
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    # ---------- Internal helpers ----------
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    def _require(self, cond, msg):
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        if not cond:
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            raise Exception(msg)
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    def _add_balance(self, who, amount):
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        self._balances[who] = self._balances.get(who, 0) + amount
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    def _sub_balance(self, who, amount):
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        bal = self.balanceOf(who)
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        self._require(bal >= amount, "Insufficient balance")
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        self._balances[who] = bal - amount
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        if self._balances[who] == 0:
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            # optional cleanup
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            self._balances.pop(who, None)
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    # ---------- Actions ----------
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    def transfer(self, sender, recipient, amount_units):
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        amount_units = int(amount_units)
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        self._require(amount_units > 0, "Amount must be > 0")
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        self._require(sender != recipient, "Sender == recipient")
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        self._require(recipient is not None, "Recipient required")
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        self._sub_balance(sender, amount_units)
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        self._add_balance(recipient, amount_units)
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        return True
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    def transferMany(self, sender, pairs):
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        total = sum(int(a) for _, a in pairs)
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        self._require(total > 0, "Total must be > 0")
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        self._sub_balance(sender, total)
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        for rcpt, amt in pairs:
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            self._add_balance(rcpt, int(amt))
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        return True
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    # ---------- Conversion helpers ----------
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    @staticmethod
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    def to_units(amount_token):
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        return int(round(float(amount_token) * (10 ** MIR20.DECIMALS)))
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    @staticmethod
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    def to_token(amount_units):
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        return amount_units / float(10 ** MIR20.DECIMALS)