112 lines
2.4 KiB
Go
112 lines
2.4 KiB
Go
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package main
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import (
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"context"
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"encoding/json"
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"errors"
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"log"
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"net/http"
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"strings"
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"github.com/go-kit/kit/endpoint"
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httptransport "github.com/go-kit/kit/transport/http"
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)
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// StringService provides operations on strings.
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type StringService interface {
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Uppercase(string) (string, error)
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Count(string) int
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}
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type stringService struct{}
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func (stringService) Uppercase(s string) (string, error) {
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if s == "" {
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return "", ErrEmpty
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}
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return strings.ToUpper(s), nil
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}
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func (stringService) Count(s string) int {
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return len(s)
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}
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func main() {
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svc := stringService{}
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uppercaseHandler := httptransport.NewServer(
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makeUppercaseEndpoint(svc),
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decodeUppercaseRequest,
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encodeResponse,
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)
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countHandler := httptransport.NewServer(
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makeCountEndpoint(svc),
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decodeCountRequest,
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encodeResponse,
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)
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http.Handle("/uppercase", uppercaseHandler)
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http.Handle("/count", countHandler)
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log.Fatal(http.ListenAndServe(":8080", nil))
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}
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func makeUppercaseEndpoint(svc StringService) endpoint.Endpoint {
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return func(ctx context.Context, request interface{}) (interface{}, error) {
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req := request.(uppercaseRequest)
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v, err := svc.Uppercase(req.S)
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if err != nil {
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return uppercaseResponse{v, err.Error()}, nil
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}
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return uppercaseResponse{v, ""}, nil
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}
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}
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func makeCountEndpoint(svc StringService) endpoint.Endpoint {
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return func(ctx context.Context, request interface{}) (interface{}, error) {
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req := request.(countRequest)
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v := svc.Count(req.S)
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return countResponse{v}, nil
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}
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}
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func decodeUppercaseRequest(_ context.Context, r *http.Request) (interface{}, error) {
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var request uppercaseRequest
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if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
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return nil, err
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}
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return request, nil
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}
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func decodeCountRequest(_ context.Context, r *http.Request) (interface{}, error) {
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var request countRequest
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if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
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return nil, err
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}
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return request, nil
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}
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func encodeResponse(_ context.Context, w http.ResponseWriter, response interface{}) error {
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return json.NewEncoder(w).Encode(response)
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}
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type uppercaseRequest struct {
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S string `json:"s"`
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}
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type uppercaseResponse struct {
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V string `json:"v"`
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Err string `json:"err,omitempty"` // errors don't define JSON marshaling
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}
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type countRequest struct {
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S string `json:"s"`
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}
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type countResponse struct {
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V int `json:"v"`
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}
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// ErrEmpty is returned when an input string is empty.
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var ErrEmpty = errors.New("empty string")
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