RosettaCodeData/Task/Array-concatenation/Go/array-concatenation-2.go

58 lines
1.5 KiB
Go

package main
import (
"reflect"
"fmt"
)
// Generic version
// Easier to make the generic version accept any number of arguments,
// and loop trough them. Otherwise there will be lots of code duplication.
func ArrayConcat(arrays ...interface{}) interface{} {
if len(arrays) == 0 {
panic("Need at least one arguemnt")
}
var vals = make([]*reflect.SliceValue, len(arrays))
var arrtype *reflect.SliceType
var totalsize int
for i,a := range arrays {
v := reflect.NewValue(a)
switch t := v.Type().(type) {
case *reflect.SliceType:
if arrtype == nil {
arrtype = t
} else if t != arrtype {
panic("Unequal types")
}
vals[i] = v.(*reflect.SliceValue)
totalsize += vals[i].Len()
default: panic("not a slice")
}
}
ret := reflect.MakeSlice(arrtype,totalsize,totalsize)
targ := ret
for _,v := range vals {
reflect.Copy(targ, v)
targ = targ.Slice(v.Len(),targ.Len())
}
return ret.Interface()
}
// Type specific version
func ArrayConcatInts(a, b []int) []int {
ret := make([]int, len(a) + len(b))
copy(ret, a)
copy(ret[len(a):], b)
return ret
}
func main() {
test1_a, test1_b := []int{1,2,3}, []int{4,5,6}
test1_c := ArrayConcatInts(test1_a, test1_b)
fmt.Println(test1_a, " + ", test1_b, " = ", test1_c)
test2_a, test2_b := []string{"a","b","c"}, []string{"d","e","f"}
test2_c := ArrayConcat(test2_a, test2_b).([]string)
fmt.Println(test2_a, " + ", test2_b, " = ", test2_c)
}