intercepting_writer.go

Documentation: github.com/go-kit/kit/transport/http

     1  package http
     2  
     3  import (
     4  	"io"
     5  	"net/http"
     6  )
     7  
     8  type interceptingWriter struct {
     9  	http.ResponseWriter
    10  	code    int
    11  	written int64
    12  }
    13  
    14  // WriteHeader may not be explicitly called, so care must be taken to
    15  // initialize w.code to its default value of http.StatusOK.
    16  func (w *interceptingWriter) WriteHeader(code int) {
    17  	w.code = code
    18  	w.ResponseWriter.WriteHeader(code)
    19  }
    20  
    21  func (w *interceptingWriter) Write(p []byte) (int, error) {
    22  	n, err := w.ResponseWriter.Write(p)
    23  	w.written += int64(n)
    24  	return n, err
    25  }
    26  
    27  // reimplementInterfaces returns a wrapped version of the embedded ResponseWriter
    28  // and selectively implements the same combination of additional interfaces as
    29  // the wrapped one. The interfaces it may implement are: http.Hijacker,
    30  // http.CloseNotifier, http.Pusher, http.Flusher and io.ReaderFrom. The standard
    31  // library is known to assert the existence of these interfaces and behaves
    32  // differently. This implementation is derived from
    33  // https://github.com/felixge/httpsnoop.
    34  func (w *interceptingWriter) reimplementInterfaces() http.ResponseWriter {
    35  	var (
    36  		hj, i0 = w.ResponseWriter.(http.Hijacker)
    37  		cn, i1 = w.ResponseWriter.(http.CloseNotifier)
    38  		pu, i2 = w.ResponseWriter.(http.Pusher)
    39  		fl, i3 = w.ResponseWriter.(http.Flusher)
    40  		rf, i4 = w.ResponseWriter.(io.ReaderFrom)
    41  	)
    42  
    43  	switch {
    44  	case !i0 && !i1 && !i2 && !i3 && !i4:
    45  		return struct {
    46  			http.ResponseWriter
    47  		}{w}
    48  	case !i0 && !i1 && !i2 && !i3 && i4:
    49  		return struct {
    50  			http.ResponseWriter
    51  			io.ReaderFrom
    52  		}{w, rf}
    53  	case !i0 && !i1 && !i2 && i3 && !i4:
    54  		return struct {
    55  			http.ResponseWriter
    56  			http.Flusher
    57  		}{w, fl}
    58  	case !i0 && !i1 && !i2 && i3 && i4:
    59  		return struct {
    60  			http.ResponseWriter
    61  			http.Flusher
    62  			io.ReaderFrom
    63  		}{w, fl, rf}
    64  	case !i0 && !i1 && i2 && !i3 && !i4:
    65  		return struct {
    66  			http.ResponseWriter
    67  			http.Pusher
    68  		}{w, pu}
    69  	case !i0 && !i1 && i2 && !i3 && i4:
    70  		return struct {
    71  			http.ResponseWriter
    72  			http.Pusher
    73  			io.ReaderFrom
    74  		}{w, pu, rf}
    75  	case !i0 && !i1 && i2 && i3 && !i4:
    76  		return struct {
    77  			http.ResponseWriter
    78  			http.Pusher
    79  			http.Flusher
    80  		}{w, pu, fl}
    81  	case !i0 && !i1 && i2 && i3 && i4:
    82  		return struct {
    83  			http.ResponseWriter
    84  			http.Pusher
    85  			http.Flusher
    86  			io.ReaderFrom
    87  		}{w, pu, fl, rf}
    88  	case !i0 && i1 && !i2 && !i3 && !i4:
    89  		return struct {
    90  			http.ResponseWriter
    91  			http.CloseNotifier
    92  		}{w, cn}
    93  	case !i0 && i1 && !i2 && !i3 && i4:
    94  		return struct {
    95  			http.ResponseWriter
    96  			http.CloseNotifier
    97  			io.ReaderFrom
    98  		}{w, cn, rf}
    99  	case !i0 && i1 && !i2 && i3 && !i4:
   100  		return struct {
   101  			http.ResponseWriter
   102  			http.CloseNotifier
   103  			http.Flusher
   104  		}{w, cn, fl}
   105  	case !i0 && i1 && !i2 && i3 && i4:
   106  		return struct {
   107  			http.ResponseWriter
   108  			http.CloseNotifier
   109  			http.Flusher
   110  			io.ReaderFrom
   111  		}{w, cn, fl, rf}
   112  	case !i0 && i1 && i2 && !i3 && !i4:
   113  		return struct {
   114  			http.ResponseWriter
   115  			http.CloseNotifier
   116  			http.Pusher
   117  		}{w, cn, pu}
   118  	case !i0 && i1 && i2 && !i3 && i4:
   119  		return struct {
   120  			http.ResponseWriter
   121  			http.CloseNotifier
   122  			http.Pusher
   123  			io.ReaderFrom
   124  		}{w, cn, pu, rf}
   125  	case !i0 && i1 && i2 && i3 && !i4:
   126  		return struct {
   127  			http.ResponseWriter
   128  			http.CloseNotifier
   129  			http.Pusher
   130  			http.Flusher
   131  		}{w, cn, pu, fl}
   132  	case !i0 && i1 && i2 && i3 && i4:
   133  		return struct {
   134  			http.ResponseWriter
   135  			http.CloseNotifier
   136  			http.Pusher
   137  			http.Flusher
   138  			io.ReaderFrom
   139  		}{w, cn, pu, fl, rf}
   140  	case i0 && !i1 && !i2 && !i3 && !i4:
   141  		return struct {
   142  			http.ResponseWriter
   143  			http.Hijacker
   144  		}{w, hj}
   145  	case i0 && !i1 && !i2 && !i3 && i4:
   146  		return struct {
   147  			http.ResponseWriter
   148  			http.Hijacker
   149  			io.ReaderFrom
   150  		}{w, hj, rf}
   151  	case i0 && !i1 && !i2 && i3 && !i4:
   152  		return struct {
   153  			http.ResponseWriter
   154  			http.Hijacker
   155  			http.Flusher
   156  		}{w, hj, fl}
   157  	case i0 && !i1 && !i2 && i3 && i4:
   158  		return struct {
   159  			http.ResponseWriter
   160  			http.Hijacker
   161  			http.Flusher
   162  			io.ReaderFrom
   163  		}{w, hj, fl, rf}
   164  	case i0 && !i1 && i2 && !i3 && !i4:
   165  		return struct {
   166  			http.ResponseWriter
   167  			http.Hijacker
   168  			http.Pusher
   169  		}{w, hj, pu}
   170  	case i0 && !i1 && i2 && !i3 && i4:
   171  		return struct {
   172  			http.ResponseWriter
   173  			http.Hijacker
   174  			http.Pusher
   175  			io.ReaderFrom
   176  		}{w, hj, pu, rf}
   177  	case i0 && !i1 && i2 && i3 && !i4:
   178  		return struct {
   179  			http.ResponseWriter
   180  			http.Hijacker
   181  			http.Pusher
   182  			http.Flusher
   183  		}{w, hj, pu, fl}
   184  	case i0 && !i1 && i2 && i3 && i4:
   185  		return struct {
   186  			http.ResponseWriter
   187  			http.Hijacker
   188  			http.Pusher
   189  			http.Flusher
   190  			io.ReaderFrom
   191  		}{w, hj, pu, fl, rf}
   192  	case i0 && i1 && !i2 && !i3 && !i4:
   193  		return struct {
   194  			http.ResponseWriter
   195  			http.Hijacker
   196  			http.CloseNotifier
   197  		}{w, hj, cn}
   198  	case i0 && i1 && !i2 && !i3 && i4:
   199  		return struct {
   200  			http.ResponseWriter
   201  			http.Hijacker
   202  			http.CloseNotifier
   203  			io.ReaderFrom
   204  		}{w, hj, cn, rf}
   205  	case i0 && i1 && !i2 && i3 && !i4:
   206  		return struct {
   207  			http.ResponseWriter
   208  			http.Hijacker
   209  			http.CloseNotifier
   210  			http.Flusher
   211  		}{w, hj, cn, fl}
   212  	case i0 && i1 && !i2 && i3 && i4:
   213  		return struct {
   214  			http.ResponseWriter
   215  			http.Hijacker
   216  			http.CloseNotifier
   217  			http.Flusher
   218  			io.ReaderFrom
   219  		}{w, hj, cn, fl, rf}
   220  	case i0 && i1 && i2 && !i3 && !i4:
   221  		return struct {
   222  			http.ResponseWriter
   223  			http.Hijacker
   224  			http.CloseNotifier
   225  			http.Pusher
   226  		}{w, hj, cn, pu}
   227  	case i0 && i1 && i2 && !i3 && i4:
   228  		return struct {
   229  			http.ResponseWriter
   230  			http.Hijacker
   231  			http.CloseNotifier
   232  			http.Pusher
   233  			io.ReaderFrom
   234  		}{w, hj, cn, pu, rf}
   235  	case i0 && i1 && i2 && i3 && !i4:
   236  		return struct {
   237  			http.ResponseWriter
   238  			http.Hijacker
   239  			http.CloseNotifier
   240  			http.Pusher
   241  			http.Flusher
   242  		}{w, hj, cn, pu, fl}
   243  	case i0 && i1 && i2 && i3 && i4:
   244  		return struct {
   245  			http.ResponseWriter
   246  			http.Hijacker
   247  			http.CloseNotifier
   248  			http.Pusher
   249  			http.Flusher
   250  			io.ReaderFrom
   251  		}{w, hj, cn, pu, fl, rf}
   252  	default:
   253  		return struct {
   254  			http.ResponseWriter
   255  		}{w}
   256  	}
   257  }
   258
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