micro-server-http/server.go

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package http
import (
"context"
"fmt"
"reflect"
"unicode"
"unicode/utf8"
"github.com/unistack-org/micro/v3/server"
)
type methodType struct {
ArgType reflect.Type
ReplyType reflect.Type
ContextType reflect.Type
method reflect.Method
stream bool
}
// Is this an exported - upper case - name?
func isExported(name string) bool {
r, _ := utf8.DecodeRuneInString(name)
return unicode.IsUpper(r)
}
// Is this type exported or a builtin?
func isExportedOrBuiltinType(t reflect.Type) bool {
for t.Kind() == reflect.Ptr {
t = t.Elem()
}
// PkgPath will be non-empty even for an exported type,
// so we need to check the type name as well.
return isExported(t.Name()) || t.PkgPath() == ""
}
// prepareEndpoint() returns a methodType for the provided method or nil
// in case if the method was unsuitable.
func prepareEndpoint(method reflect.Method) (*methodType, error) {
mtype := method.Type
mname := method.Name
var replyType, argType, contextType reflect.Type
var stream bool
// Endpoint() must be exported.
if method.PkgPath != "" {
return nil, fmt.Errorf("Endpoint must be exported")
}
switch mtype.NumIn() {
case 3:
// assuming streaming
argType = mtype.In(2)
contextType = mtype.In(1)
stream = true
case 4:
// method that takes a context
argType = mtype.In(2)
replyType = mtype.In(3)
contextType = mtype.In(1)
default:
return nil, fmt.Errorf("method %v of %v has wrong number of ins: %v", mname, mtype, mtype.NumIn())
}
switch stream {
case true:
// check stream type
streamType := reflect.TypeOf((*server.Stream)(nil)).Elem()
if !argType.Implements(streamType) {
return nil, fmt.Errorf("%v argument does not implement Streamer interface: %v", mname, argType)
}
default:
// First arg need not be a pointer.
if !isExportedOrBuiltinType(argType) {
return nil, fmt.Errorf("%v argument type not exported: %v", mname, argType)
}
if replyType.Kind() != reflect.Ptr {
return nil, fmt.Errorf("method %v reply type not a pointer: %v", mname, replyType)
}
// Reply type must be exported.
if !isExportedOrBuiltinType(replyType) {
return nil, fmt.Errorf("method %v reply type not exported: %v", mname, replyType)
}
}
// Endpoint() needs one out.
if mtype.NumOut() != 1 {
return nil, fmt.Errorf("method %v has wrong number of outs: %v", mname, mtype.NumOut())
}
// The return type of the method must be error.
if returnType := mtype.Out(0); returnType != typeOfError {
return nil, fmt.Errorf("method %v returns %v not error", mname, returnType.String())
}
return &methodType{method: method, ArgType: argType, ReplyType: replyType, ContextType: contextType, stream: stream}, nil
}
func (m *methodType) prepareContext(ctx context.Context) reflect.Value {
if contextv := reflect.ValueOf(ctx); contextv.IsValid() {
return contextv
}
return reflect.Zero(m.ContextType)
}