route/vendor/github.com/grpc-ecosystem/grpc-gateway/runtime/marshaler_registry.go

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2017-01-26 15:51:44 +00:00
package runtime
import (
"errors"
"net/http"
)
// MIMEWildcard is the fallback MIME type used for requests which do not match
// a registered MIME type.
const MIMEWildcard = "*"
var (
acceptHeader = http.CanonicalHeaderKey("Accept")
contentTypeHeader = http.CanonicalHeaderKey("Content-Type")
defaultMarshaler = &JSONPb{OrigName: true}
)
// MarshalerForRequest returns the inbound/outbound marshalers for this request.
// It checks the registry on the ServeMux for the MIME type set by the Content-Type header.
// If it isn't set (or the request Content-Type is empty), checks for "*".
// If there are multiple Content-Type headers set, choose the first one that it can
// exactly match in the registry.
// Otherwise, it follows the above logic for "*"/InboundMarshaler/OutboundMarshaler.
func MarshalerForRequest(mux *ServeMux, r *http.Request) (inbound Marshaler, outbound Marshaler) {
for _, acceptVal := range r.Header[acceptHeader] {
if m, ok := mux.marshalers.mimeMap[acceptVal]; ok {
outbound = m
break
}
}
for _, contentTypeVal := range r.Header[contentTypeHeader] {
if m, ok := mux.marshalers.mimeMap[contentTypeVal]; ok {
inbound = m
break
}
}
if inbound == nil {
inbound = mux.marshalers.mimeMap[MIMEWildcard]
}
if outbound == nil {
outbound = inbound
}
return inbound, outbound
}
// marshalerRegistry is a mapping from MIME types to Marshalers.
type marshalerRegistry struct {
mimeMap map[string]Marshaler
}
// add adds a marshaler for a case-sensitive MIME type string ("*" to match any
// MIME type).
func (m marshalerRegistry) add(mime string, marshaler Marshaler) error {
if len(mime) == 0 {
return errors.New("empty MIME type")
}
m.mimeMap[mime] = marshaler
return nil
}
// makeMarshalerMIMERegistry returns a new registry of marshalers.
// It allows for a mapping of case-sensitive Content-Type MIME type string to runtime.Marshaler interfaces.
//
// For example, you could allow the client to specify the use of the runtime.JSONPb marshaler
// with a "applicaton/jsonpb" Content-Type and the use of the runtime.JSONBuiltin marshaler
// with a "application/json" Content-Type.
// "*" can be used to match any Content-Type.
// This can be attached to a ServerMux with the marshaler option.
func makeMarshalerMIMERegistry() marshalerRegistry {
return marshalerRegistry{
mimeMap: map[string]Marshaler{
MIMEWildcard: defaultMarshaler,
},
}
}
// WithMarshalerOption returns a ServeMuxOption which associates inbound and outbound
// Marshalers to a MIME type in mux.
func WithMarshalerOption(mime string, marshaler Marshaler) ServeMuxOption {
return func(mux *ServeMux) {
if err := mux.marshalers.add(mime, marshaler); err != nil {
panic(err)
}
}
}