83 lines
2.9 KiB
D
83 lines
2.9 KiB
D
module util.money;
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import std.traits : isSomeString, EnumMembers;
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/**
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* Basic information about a monetary currency, as defined by ISO 4217.
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* https://en.wikipedia.org/wiki/ISO_4217
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*/
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struct Currency {
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/// The common 3-character code for the currency, like "USD".
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immutable char[3] code;
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/// The number of digits after the decimal place that the currency supports.
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immutable ubyte fractionalDigits;
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/// The ISO 4217 numeric code for the currency.
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immutable ushort numericCode;
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static Currency ofCode(S)(S code) if (isSomeString!S) {
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if (code.length != 3) {
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throw new Exception("Invalid currency code: " ~ code);
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}
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static foreach (c; ALL_CURRENCIES) {
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if (c.code == code) return c;
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}
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throw new Exception("Unknown currency code: " ~ code);
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}
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}
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/// An enumeration of all available currencies.
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enum Currencies : Currency {
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AUD = Currency("AUD", 2, 36),
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USD = Currency("USD", 2, 840),
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CAD = Currency("CAD", 2, 124),
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GBP = Currency("GBP", 2, 826),
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EUR = Currency("EUR", 2, 978),
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CHF = Currency("CHF", 2, 756),
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ZAR = Currency("ZAR", 2, 710),
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JPY = Currency("JPY", 0, 392),
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INR = Currency("INR", 2, 356)
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}
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immutable(Currency[]) ALL_CURRENCIES = cast(Currency[]) [EnumMembers!Currencies];
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unittest {
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assert(Currency.ofCode("USD") == Currencies.USD);
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}
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/**
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* A monetary value consisting of an integer value, and a currency. The value
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* is interpreted as a multiple of the smallest denomination of the currency,
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* so for example, with USD currency, a value of 123 indicates $1.23.
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*/
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struct MoneyValue {
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immutable Currency currency;
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immutable long value;
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int opCmp(in MoneyValue other) const {
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if (other.currency != this.currency) return 0;
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if (this.value < other.value) return -1;
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if (this.value > other.value) return 1;
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return 0;
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}
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MoneyValue opBinary(string op)(in MoneyValue rhs) const {
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if (rhs.currency != this.currency)
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throw new Exception("Cannot perform binary operations on MoneyValues with different currencies.");
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static if (op == "+") return MoneyValue(currency, this.value + rhs.value);
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static if (op == "-") return MoneyValue(currency, this.value - rhs.value);
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static assert(false, "Operator " ~ op ~ " is not supported.");
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}
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MoneyValue opBinary(string op)(int rhs) const {
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static if (op == "+") return MoneyValue(currency, this.value + rhs);
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static if (op == "-") return MoneyValue(currency, this.value - rhs);
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static if (op == "*") return MoneyValue(currency, this.value * rhs);
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static if (op == "/") return MoneyValue(currency, this.value / rhs);
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static assert(false, "Operator " ~ op ~ " is not supported.");
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}
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MoneyValue opUnary(string op)() const {
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static if (op == "-") return MoneyValue(currency, -this.value);
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static assert(false, "Operator " ~ op ~ " is not supported.");
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}
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} |