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ReasnoReasno
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feat(http): make interceptingWriter reimplement common interfaces from stdlib. (#1212)
successor to #1093 and closes #1092.
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3 files changed

+1297
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‎transport/http/intercepting_writer.go

+257
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package http
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import (
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"io"
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"net/http"
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)
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type interceptingWriter struct {
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http.ResponseWriter
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code int
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written int64
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}
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// WriteHeader may not be explicitly called, so care must be taken to
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// initialize w.code to its default value of http.StatusOK.
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func (w *interceptingWriter) WriteHeader(code int) {
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w.code = code
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w.ResponseWriter.WriteHeader(code)
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}
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func (w *interceptingWriter) Write(p []byte) (int, error) {
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n, err := w.ResponseWriter.Write(p)
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w.written += int64(n)
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return n, err
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}
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// reimplementInterfaces returns a wrapped version of the embedded ResponseWriter
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// and selectively implements the same combination of additional interfaces as
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// the wrapped one. The interfaces it may implement are: http.Hijacker,
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// http.CloseNotifier, http.Pusher, http.Flusher and io.ReaderFrom. The standard
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// library is known to assert the existence of these interfaces and behaves
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// differently. This implementation is derived from
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// https://github.com/felixge/httpsnoop.
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func (w *interceptingWriter) reimplementInterfaces() http.ResponseWriter {
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var (
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hj, i0 = w.ResponseWriter.(http.Hijacker)
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cn, i1 = w.ResponseWriter.(http.CloseNotifier)
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pu, i2 = w.ResponseWriter.(http.Pusher)
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fl, i3 = w.ResponseWriter.(http.Flusher)
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rf, i4 = w.ResponseWriter.(io.ReaderFrom)
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)
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switch {
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case !i0 && !i1 && !i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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}{w}
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case !i0 && !i1 && !i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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io.ReaderFrom
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}{w, rf}
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case !i0 && !i1 && !i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Flusher
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}{w, fl}
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case !i0 && !i1 && !i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.Flusher
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io.ReaderFrom
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}{w, fl, rf}
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case !i0 && !i1 && i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Pusher
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}{w, pu}
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case !i0 && !i1 && i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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http.Pusher
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io.ReaderFrom
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}{w, pu, rf}
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case !i0 && !i1 && i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Pusher
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http.Flusher
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}{w, pu, fl}
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case !i0 && !i1 && i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.Pusher
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http.Flusher
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io.ReaderFrom
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}{w, pu, fl, rf}
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case !i0 && i1 && !i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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}{w, cn}
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case !i0 && i1 && !i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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io.ReaderFrom
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}{w, cn, rf}
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case !i0 && i1 && !i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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http.Flusher
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}{w, cn, fl}
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case !i0 && i1 && !i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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http.Flusher
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io.ReaderFrom
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}{w, cn, fl, rf}
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case !i0 && i1 && i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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http.Pusher
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}{w, cn, pu}
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case !i0 && i1 && i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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http.Pusher
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io.ReaderFrom
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}{w, cn, pu, rf}
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case !i0 && i1 && i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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http.Pusher
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http.Flusher
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}{w, cn, pu, fl}
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case !i0 && i1 && i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.CloseNotifier
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http.Pusher
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http.Flusher
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io.ReaderFrom
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}{w, cn, pu, fl, rf}
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case i0 && !i1 && !i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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}{w, hj}
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case i0 && !i1 && !i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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io.ReaderFrom
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}{w, hj, rf}
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case i0 && !i1 && !i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.Flusher
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}{w, hj, fl}
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case i0 && !i1 && !i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.Flusher
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io.ReaderFrom
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}{w, hj, fl, rf}
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case i0 && !i1 && i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.Pusher
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}{w, hj, pu}
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case i0 && !i1 && i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.Pusher
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io.ReaderFrom
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}{w, hj, pu, rf}
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case i0 && !i1 && i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.Pusher
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http.Flusher
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}{w, hj, pu, fl}
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case i0 && !i1 && i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.Pusher
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http.Flusher
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io.ReaderFrom
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}{w, hj, pu, fl, rf}
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case i0 && i1 && !i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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}{w, hj, cn}
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case i0 && i1 && !i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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io.ReaderFrom
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}{w, hj, cn, rf}
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case i0 && i1 && !i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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http.Flusher
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}{w, hj, cn, fl}
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case i0 && i1 && !i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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http.Flusher
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io.ReaderFrom
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}{w, hj, cn, fl, rf}
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case i0 && i1 && i2 && !i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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http.Pusher
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}{w, hj, cn, pu}
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case i0 && i1 && i2 && !i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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http.Pusher
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io.ReaderFrom
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}{w, hj, cn, pu, rf}
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case i0 && i1 && i2 && i3 && !i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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http.Pusher
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http.Flusher
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}{w, hj, cn, pu, fl}
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case i0 && i1 && i2 && i3 && i4:
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return struct {
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http.ResponseWriter
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http.Hijacker
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http.CloseNotifier
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http.Pusher
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http.Flusher
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io.ReaderFrom
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}{w, hj, cn, pu, fl, rf}
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default:
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return struct {
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http.ResponseWriter
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}{w}
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}
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}

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