claude 0.4.0

A little library to represent money.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184

//! Implementations of standard operators:  `Add`, `Sub`, `Mul`, `Div`

use crate::Currency;
use std::ops::{Add, Div, Mul, Sub};

/// Overloads the '+' operator for Currency objects.
///
/// # Panics
/// Panics if the two addends are different types of currency, as denoted by the Currency's symbol.
impl Add for Currency {
    type Output = Currency;

    #[inline]
    fn add(self, rhs: Currency) -> Currency {
        if self.symbol == rhs.symbol || self.symbol.is_none() {
            Currency {
                symbol: rhs.symbol,
                value: self.value + rhs.value,
            }
        } else {
            panic!(
                "Cannot add two different types of currency!\n{:?} vs {:?}",
                self.symbol, rhs.symbol
            );
        }
    }
}

/// Overloads the '-' operator for Currency objects.
///
/// # Panics
/// Panics if the minuend and subtrahend are two different types of currency, as denoted by the
/// Currency's symbol.
impl Sub for Currency {
    type Output = Currency;

    #[inline]
    fn sub(self, rhs: Currency) -> Currency {
        if self.symbol == rhs.symbol || self.symbol.is_none() {
            Currency {
                symbol: rhs.symbol,
                value: self.value - rhs.value,
            }
        } else {
            panic!("Cannot subtract two different types of currency!");
        }
    }
}

/// Overloads the '*' operator for Currency objects.
///
/// Allows a Currency to be multiplied by an i64.
impl Mul<i64> for Currency {
    type Output = Currency;

    #[inline]
    fn mul(self, rhs: i64) -> Currency {
        Currency {
            symbol: self.symbol,
            value: self.value * rhs,
        }
    }
}

/// Overloads the '*' operator for i64.
///
/// Allows an i64 to be multiplied by a Currency.
/// Completes the commutative property for i64 multiplied by Currency.
impl Mul<Currency> for i64 {
    type Output = Currency;

    #[inline]
    fn mul(self, rhs: Currency) -> Currency {
        Currency {
            symbol: rhs.symbol,
            value: rhs.value * self,
        }
    }
}

/// Multiplies with float, probably not a good idea, help appreciated.
impl Mul<f64> for Currency {
    type Output = Currency;

    #[inline]
    fn mul(self, rhs: f64) -> Currency {
        Currency {
            symbol: self.symbol,
            value: (self.value as f64 * rhs).round() as i64,
        }
    }
}

impl Mul<Currency> for f64 {
    type Output = Currency;

    #[inline]
    fn mul(self, rhs: Currency) -> Currency {
        rhs * self
    }
}

/// Overloads the '/' operator for Currency objects.
///
/// Allows a Currency to be divided by an i64.
impl Div<i64> for Currency {
    type Output = Currency;

    #[inline]
    fn div(self, rhs: i64) -> Currency {
        Currency {
            symbol: self.symbol,
            value: self.value / rhs,
        }
    }
}

#[cfg(test)]
mod test_arithmetic {
    use crate::Currency;

    fn dollars(value: i64) -> Currency {
        Currency {
            symbol: Some('$'),
            value,
        }
    }

    fn bare(value: i64) -> Currency {
        Currency::from_value(value)
    }

    #[test]
    fn sub_same_symbol() {
        assert_eq!(dollars(100) - dollars(50), dollars(50));
    }

    #[test]
    fn add_same_symbol() {
        assert_eq!(dollars(100) + dollars(50), dollars(150));
    }

    #[test]
    fn bare_lhs_adopts_rhs_symbol_on_add() {
        assert_eq!(bare(100) + dollars(50), dollars(150));
    }

    #[test]
    fn bare_lhs_adopts_rhs_symbol_on_sub() {
        assert_eq!(bare(100) - dollars(50), dollars(50));
    }

    #[test]
    #[should_panic]
    fn symbolled_lhs_plus_bare_rhs_panics() {
        let _ = dollars(100) + bare(50);
    }

    #[test]
    #[should_panic]
    fn symbolled_lhs_minus_bare_rhs_panics() {
        let _ = dollars(100) - bare(50);
    }

    #[test]
    #[should_panic]
    fn mixed_symbols_add_panics() {
        let euro = Currency {
            symbol: Some('€'),
            value: 100,
        };
        let _ = dollars(100) + euro;
    }

    #[test]
    #[should_panic]
    fn mixed_symbols_sub_panics() {
        let euro = Currency {
            symbol: Some('€'),
            value: 100,
        };
        let _ = dollars(100) - euro;
    }
}