X-Git-Url: https://wannabe.guru.org/gitweb/?a=blobdiff_plain;f=type%2Fmoney.py;fp=type%2Fmoney.py;h=c77a9389391201c47528bcc1f87bbf7e79134e02;hb=4faa994d32223c8d560d9dad0ca90a3f7eb10d6a;hp=0000000000000000000000000000000000000000;hpb=c79ecbf708a63a54a9c3e8d189b65d4794930082;p=python_utils.git

diff --git a/type/money.py b/type/money.py
new file mode 100644
index 0000000..c77a938
--- /dev/null
+++ b/type/money.py
@@ -0,0 +1,227 @@
+#!/usr/bin/env python3
+
+from decimal import Decimal
+import re
+from typing import Optional, TypeVar, Tuple
+
+import math_utils
+
+
+T = TypeVar('T', bound='Money')
+
+
+class Money(object):
+    """A class for representing monetary amounts potentially with
+    different currencies.
+    """
+
+    def __init__ (
+            self,
+            amount: Decimal = Decimal("0.0"),
+            currency: str = 'USD',
+            *,
+            strict_mode = False
+    ):
+        self.strict_mode = strict_mode
+        if isinstance(amount, str):
+            ret = Money._parse(amount)
+            if ret is None:
+                raise Exception(f'Unable to parse money string "{amount}"')
+            amount = ret[0]
+            currency = ret[1]
+        if not isinstance(amount, Decimal):
+            amount = Decimal(float(amount))
+        self.amount = amount
+        if not currency:
+            self.currency: Optional[str] = None
+        else:
+            self.currency: Optional[str] = currency
+
+    def __repr__(self):
+        a = float(self.amount)
+        a = round(a, 2)
+        s = f'{a:,.2f}'
+        if self.currency is not None:
+            return '%s %s' % (s, self.currency)
+        else:
+            return '$%s' % s
+
+    def __pos__(self):
+        return Money(amount=self.amount, currency=self.currency)
+
+    def __neg__(self):
+        return Money(amount=-self.amount, currency=self.currency)
+
+    def __add__(self, other):
+        if isinstance(other, Money):
+            if self.currency == other.currency:
+                return Money(
+                    amount = self.amount + other.amount,
+                    currency = self.currency
+                )
+            else:
+                raise TypeError('Incompatible currencies in add expression')
+        else:
+            if self.strict_mode:
+                raise TypeError('In strict_mode only two moneys can be added')
+            else:
+                return Money(
+                    amount = self.amount + Decimal(float(other)),
+                    currency = self.currency
+                )
+
+    def __sub__(self, other):
+        if isinstance(other, Money):
+            if self.currency == other.currency:
+                return Money(
+                    amount = self.amount - other.amount,
+                    currency = self.currency
+                )
+            else:
+                raise TypeError('Incompatible currencies in add expression')
+        else:
+            if self.strict_mode:
+                raise TypeError('In strict_mode only two moneys can be added')
+            else:
+                return Money(
+                    amount = self.amount - Decimal(float(other)),
+                    currency = self.currency
+                )
+
+    def __mul__(self, other):
+        if isinstance(other, Money):
+            raise TypeError('can not multiply monetary quantities')
+        else:
+            return Money(
+                amount = self.amount * Decimal(float(other)),
+                currency = self.currency
+            )
+
+    def __truediv__(self, other):
+        if isinstance(other, Money):
+            raise TypeError('can not divide monetary quantities')
+        else:
+            return Money(
+                amount = self.amount / Decimal(float(other)),
+                currency = self.currency
+            )
+
+    def __float__(self):
+        return self.amount.__float__()
+
+    def truncate_fractional_cents(self):
+        x = float(self)
+        self.amount = Decimal(math_utils.truncate_float(x))
+        return self.amount
+
+    def round_fractional_cents(self):
+        x = float(self)
+        self.amount = Decimal(round(x, 2))
+        return self.amount
+
+    __radd__ = __add__
+
+    def __rsub__(self, other):
+        if isinstance(other, Money):
+            if self.currency == other.currency:
+                return Money(
+                    amount = other.amount - self.amount,
+                    currency = self.currency
+                )
+            else:
+                raise TypeError('Incompatible currencies in sub expression')
+        else:
+            if self.strict_mode:
+                raise TypeError('In strict_mode only two moneys can be added')
+            else:
+                return Money(
+                    amount = Decimal(float(other)) - self.amount,
+                    currency = self.currency
+                )
+
+    __rmul__ = __mul__
+
+    #
+    # Override comparison operators to also compare currency.
+    #
+    def __eq__(self, other):
+        if other is None:
+            return False
+        if isinstance(other, Money):
+            return (
+                self.amount == other.amount and
+                self.currency == other.currency
+            )
+        if self.strict_mode:
+            raise TypeError("In strict mode only two Moneys can be compared")
+        else:
+            return self.amount == Decimal(float(other))
+
+    def __ne__(self, other):
+        result = self.__eq__(other)
+        if result is NotImplemented:
+            return result
+        return not result
+
+    def __lt__(self, other):
+        if isinstance(other, Money):
+            if self.currency == other.currency:
+                return self.amount < other.amount
+            else:
+                raise TypeError('can not directly compare different currencies')
+        else:
+            if self.strict_mode:
+                raise TypeError('In strict mode, only two Moneys can be compated')
+            else:
+                return self.amount < Decimal(float(other))
+
+    def __gt__(self, other):
+        if isinstance(other, Money):
+            if self.currency == other.currency:
+                return self.amount > other.amount
+            else:
+                raise TypeError('can not directly compare different currencies')
+        else:
+            if self.strict_mode:
+                raise TypeError('In strict mode, only two Moneys can be compated')
+            else:
+                return self.amount > Decimal(float(other))
+
+    def __le__(self, other):
+        return self < other or self == other
+
+    def __ge__(self, other):
+        return self > other or self == other
+
+    def __hash__(self):
+        return self.__repr__
+
+    AMOUNT_RE = re.compile("^([+|-]?)(\d+)(\.\d+)$")
+    CURRENCY_RE = re.compile("^[A-Z][A-Z][A-Z]$")
+
+    @classmethod
+    def _parse(cls, s: str) -> Optional[Tuple[Decimal, str]]:
+        amount = None
+        currency = None
+        s = s.strip()
+        chunks = s.split(' ')
+        try:
+            for chunk in chunks:
+                if Money.AMOUNT_RE.match(chunk) is not None:
+                    amount = Decimal(chunk)
+                elif Money.CURRENCY_RE.match(chunk) is not None:
+                    currency = chunk
+        except:
+            pass
+        if amount is not None and currency is not None:
+            return (amount, currency)
+        elif amount is not None:
+            return (amount, 'USD')
+        return None
+
+    @classmethod
+    def parse(cls, s: str) -> T:
+        chunks = Money._parse(s)
+        if chunks is not None:
+            return Money(chunks[0], chunks[1])
+        raise Exception(f'Unable to parse money string "{s}"')