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// Copyright 2016 John D. Hume // // Licensed under the Apache License, Version 2.0, <LICENSE-APACHE or // http://apache.org/licenses/LICENSE-2.0> or the MIT license <LICENSE-MIT or // http://opensource.org/licenses/MIT>, at your option. This file may not be // copied, modified, or distributed except according to those terms. //! Besides defining the `Currency` struct, this module provides constants for most real-world //! currencies as well as functions to look up a Currency by alphabetic or numeric code. use base26; use std::collections::HashMap; /// A monetary currency with text and numeric codes and a standard number of decimal places, /// as per [ISO 4217](https://en.wikipedia.org/wiki/ISO_4217). /// /// Three-letter currency codes are encoded in a `u16`, which is how this type can be small and /// `Copy`. /// /// ``` /// # use steel_cent::currency::*; /// assert_eq!(4, std::mem::size_of::<Currency>()); /// ``` #[derive(Debug, PartialEq, Eq, Copy, Clone, Hash)] pub struct Currency { code_base26: u16, numeric_code_and_decimal_places: u16, } impl Currency { /// Create a currency w/ the given 3-character code, 0-999 numeric code, and 0-8 decimal places. /// Panics if any arg violates those constraints. This function has no connection to the /// global currency maps used by lookup functions, so creating a custom currency won't cause it /// to show up in look-ups. pub fn new(code: &str, numeric_code: u16, decimal_places: u8) -> Self { assert!(numeric_code < 1000, "Currency numeric code must be less than 1000"); assert!(decimal_places < 9, "Currency decimal places must be less than 9"); Currency { code_base26: base26::code_to_base26(code), numeric_code_and_decimal_places: (numeric_code * 10) + (decimal_places as u16), } } /// ``` /// # use steel_cent::currency::*; /// assert_eq!("AUD", AUD.code()); /// assert_eq!("CAD", CAD.code()); /// assert_eq!("CHF", CHF.code()); /// assert_eq!("EUR", EUR.code()); /// assert_eq!("GBP", GBP.code()); /// assert_eq!("JPY", JPY.code()); /// assert_eq!("USD", USD.code()); /// assert_eq!("XTS", Currency::new("XTS", 999, 2).code()); /// ``` pub fn code(&self) -> String { base26::base26_to_code(self.code_base26) } /// ``` /// # use steel_cent::currency::*; /// assert_eq!(840, USD.numeric_code()); /// assert_eq!(392, JPY.numeric_code()); /// ``` pub fn numeric_code(&self) -> u16 { self.numeric_code_and_decimal_places / 10 } /// ``` /// # use steel_cent::currency::*; /// assert_eq!(2, USD.decimal_places()); /// assert_eq!(0, JPY.decimal_places()); /// ``` pub fn decimal_places(&self) -> u8 { (self.numeric_code_and_decimal_places % 10) as u8 } /// Converts a "major" amount to a "minor" amount in this currency. /// /// ``` /// # use steel_cent::currency::*; /// assert_eq!(100, USD.major_to_minor(1)); /// assert_eq!(100, JPY.major_to_minor(100)) /// ``` pub fn major_to_minor(&self, major: i64) -> i64 { major * self.multiplier() } /// ``` /// # use steel_cent::currency::*; /// assert_eq!(100, USD.major_to_minor_i32(1)); /// assert_eq!(100, JPY.major_to_minor_i32(100)) /// ``` pub fn major_to_minor_i32(&self, major: i32) -> i32 { major * self.multiplier() as i32 } /// Returns the major part of a minor amount. /// /// ``` /// # use steel_cent::currency::*; /// assert_eq!(12, USD.major_part(1234)); /// assert_eq!(1234, JPY.major_part(1234)); /// ``` pub fn major_part(&self, minor_amount: i64) -> i64 { minor_amount / self.multiplier() } /// ``` /// # use steel_cent::currency::*; /// assert_eq!(12, USD.major_part_i32(1234)); /// assert_eq!(1234, JPY.major_part_i32(1234)); /// ``` pub fn major_part_i32(&self, minor_amount: i32) -> i32 { minor_amount / self.multiplier() as i32 } /// Returns the minor part of a minor amount. /// /// ``` /// # use steel_cent::currency::*; /// assert_eq!(34, USD.minor_part(1234)); /// assert_eq!(0, JPY.minor_part(1234)); /// ``` pub fn minor_part(&self, minor_amount: i64) -> i64 { minor_amount % self.multiplier() } /// ``` /// # use steel_cent::currency::*; /// assert_eq!(34, USD.minor_part_i32(1234)); /// assert_eq!(0, JPY.minor_part_i32(1234)); /// ``` pub fn minor_part_i32(&self, minor_amount: i32) -> i32 { minor_amount % self.multiplier() as i32 } fn multiplier(&self) -> i64 { match self.decimal_places() { 0 => 1, 1 => 10, 2 => 100, 3 => 1000, places => 10i64.pow(places as u32), } } } include!(concat!(env!("OUT_DIR"), "/generated_currency_data")); /// Looks up a "standard" currency by its three-letter code. /// /// ``` /// # use steel_cent::currency::*; /// assert_eq!(Some(USD), with_code("USD")); /// assert_eq!(Some(GBP), with_code("GBP")); /// assert_eq!(None, with_code("WRONG")); /// ``` pub fn with_code(code: &str) -> Option<Currency> { CURRENCIES_BY_CODE.get(code).cloned() } /// Looks up a "standard" currency by its numeric code. /// /// ``` /// # use steel_cent::currency::*; /// assert_eq!(Some(USD), with_numeric_code(&840)); /// assert_eq!(Some(GBP), with_numeric_code(&826)); /// assert_eq!(None, with_numeric_code(&1000)); /// ``` pub fn with_numeric_code(code: &u16) -> Option<Currency> { CURRENCIES_BY_NUMERIC_CODE.get(code).cloned() } #[cfg(test)] mod tests { use super::*; #[test] fn currency_equality() { assert_eq!(USD, USD); assert_eq!(USD, Currency::new("USD", 840, 2)); assert!(USD != Currency::new("USD", 841, 2)); assert!(USD != Currency::new("USD", 840, 3)); assert!(USD != AUD); assert!(AUD != CAD); assert!(CHF != EUR); assert!(GBP != JPY); } #[test] fn converts_major_amount_to_minor_amount_with_silly_decimal_places() { assert_eq!(1000000, Currency::new("XTS", 0, 6).major_to_minor(1)); } }