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
|
package main
import (
"fmt"
"math"
)
// parseOperator returns a closure that performs the specified arithmetic operation,
// or OpError if op is not a valid operator.
func parseOperator(op byte) (func(lhs float64, rhs float64) float64, error) {
switch op {
case '+':
return func(lhs, rhs float64) float64 { return lhs + rhs }, nil
case '-':
return func(lhs, rhs float64) float64 { return lhs - rhs }, nil
case '*':
return func(lhs, rhs float64) float64 { return lhs * rhs }, nil
case '/':
return func(lhs, rhs float64) float64 {
if rhs != 0 {
return lhs / rhs
}
return lhs
}, nil
case '%':
return func(lhs, rhs float64) float64 {
if rhs != 0 {
return float64(int64(lhs) % int64(rhs))
}
return lhs
}, nil
case '^':
return func(lhs, rhs float64) float64 { return math.Pow(lhs, rhs) }, nil
}
return nil, OperatorErr{op}
}
// OperatorErr records an invalid arithmetic operator.
type OperatorErr struct {
c byte
}
func (e OperatorErr) Error() string {
return fmt.Sprintf("invalid operator: %c", e.c)
}
|