prometheus/vendor/go.opencensus.io/plugin/ochttp/wrapped_body.go

// Copyright 2019, OpenCensus Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package ochttp

import (
	"io"
)

// wrappedBody returns a wrapped version of the original
// Body and only implements the same combination of additional
// interfaces as the original.
func wrappedBody(wrapper io.ReadCloser, body io.ReadCloser) io.ReadCloser {
	var (
		wr, i0 = body.(io.Writer)
	)
	switch {
	case !i0:
		return struct {
			io.ReadCloser
		}{wrapper}

	case i0:
		return struct {
			io.ReadCloser
			io.Writer
		}{wrapper, wr}
	default:
		return struct {
			io.ReadCloser
		}{wrapper}
	}
}