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An experiment with Golang reflection and channels
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| package main | |
| import ( | |
| "reflect" | |
| "strings" | |
| ) | |
| func makeChannel(t reflect.Type, chanDir reflect.ChanDir, buffer int) reflect.Value { | |
| ctype := reflect.ChanOf(chanDir, t) | |
| return reflect.MakeChan(ctype, buffer) | |
| } | |
| type T interface{} | |
| type Query struct { | |
| input reflect.Value | |
| } | |
| func (q *Query) Apply(f T) *Query { | |
| value := reflect.ValueOf(f) | |
| if value.Kind() != reflect.Func { | |
| panic("Apply() parameter must be a function") | |
| } | |
| rtype := value.Type().Out(0) | |
| output := makeChannel(rtype, reflect.BothDir, 0) | |
| go func() { | |
| var elem reflect.Value | |
| for ok := true; ok; { | |
| if elem, ok = q.input.Recv(); ok { | |
| result := value.Call([]reflect.Value{elem}) | |
| output.Send(result[0]) | |
| } | |
| } | |
| output.Close() | |
| }() | |
| return &Query{output} | |
| } | |
| func From(array T) *Query { | |
| value := reflect.ValueOf(array) | |
| if value.Kind() != reflect.Slice { | |
| panic("From() parameter must be a slice") | |
| } | |
| etype := value.Type().Elem() | |
| output := makeChannel(etype, reflect.BothDir, 0) | |
| go func() { | |
| for i := 0; i != value.Len(); i++ { | |
| output.Send(value.Index(i)) | |
| } | |
| output.Close() | |
| }() | |
| return &Query{output} | |
| } | |
| func (q *Query) Items() <-chan T { | |
| output := make(chan T) | |
| go func() { | |
| for ok := true; ok; { | |
| var elem reflect.Value | |
| if elem, ok = q.input.Recv(); ok { | |
| output <- elem.Interface() | |
| } | |
| } | |
| close(output) | |
| }() | |
| return output | |
| } | |
| func (q *Query) StringItems() <-chan string { | |
| output := make(chan string) | |
| go func() { | |
| for elem := range q.Items() { | |
| output <- elem.(string) | |
| } | |
| close(output) | |
| }() | |
| return output | |
| } | |
| func main() { | |
| t := []int{0, 1, 2} | |
| m := map[int]string{0: "zero", 1: "one", 2: "two"} | |
| for elem := range From(t).Apply(func(x int) string { return m[x] }).Apply(strings.ToUpper).StringItems() { | |
| println(elem) | |
| } | |
| } |
Author
icecrime
commented
May 9, 2014
very nicely done ... good example of "reflect" and channels, thanks!
thanks! it helps me a lot.
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