merge interp: improve handling of composed interfaces wrappers

stdlib/wrapper-composed.go

@@ -0,0 +1,91 @@
+//go:build stdhttp
+// +build stdhttp
+
+package stdlib
+
+import (
+	"bufio"
+	"io"
+	"net"
+	"net/http"
+	"reflect"
+)
+
+// Wrappers for composed interfaces which trigger a special behavior in stdlib.
+// Note: it may become useless to pre-compile composed interface wrappers
+// once golang/go#15924 is resolved.
+
+// In net/http, a ResponseWriter may also implement a Hijacker.
+
+type _netHTTPResponseWriterHijacker struct {
+	IValue       interface{}
+	WHeader      func() http.Header
+	WWrite       func(a0 []byte) (int, error)
+	WWriteHeader func(statusCode int)
+
+	WHijack func() (net.Conn, *bufio.ReadWriter, error)
+}
+
+func (w _netHTTPResponseWriterHijacker) Header() http.Header {
+	return w.WHeader()
+}
+
+func (w _netHTTPResponseWriterHijacker) Write(a0 []byte) (int, error) {
+	return w.WWrite(a0)
+}
+
+func (w _netHTTPResponseWriterHijacker) WriteHeader(statusCode int) {
+	w.WWriteHeader(statusCode)
+}
+
+func (w _netHTTPResponseWriterHijacker) Hijack() (net.Conn, *bufio.ReadWriter, error) {
+	return w.WHijack()
+}
+
+// In io, a Reader may implement WriteTo, used by io.Copy().
+
+type _ioReaderWriteTo struct {
+	IValue interface{}
+	WRead  func(p []byte) (n int, err error)
+
+	WWriteTo func(w io.Writer) (n int64, err error)
+}
+
+func (w _ioReaderWriteTo) Read(p []byte) (n int, err error) {
+	return w.WRead(p)
+}
+
+func (w _ioReaderWriteTo) WriteTo(wr io.Writer) (n int64, err error) {
+	return w.WWriteTo(wr)
+}
+
+// In io, a Writer may implement ReadFrom, used by io.Copy().
+
+type _ioWriterReadFrom struct {
+	IValue interface{}
+	WWrite func(p []byte) (n int, err error)
+
+	WReadFrom func(r io.Reader) (n int64, err error)
+}
+
+func (w _ioWriterReadFrom) Write(p []byte) (n int, err error) {
+	return w.WWrite(p)
+}
+
+func (w _ioWriterReadFrom) ReadFrom(r io.Reader) (n int64, err error) {
+	return w.WReadFrom(r)
+}
+
+// Each MapType value (each slice) must be sorted by complexity, i.e. by number
+// of interface methods.
+func init() {
+	MapTypes[reflect.ValueOf((*_net_http_ResponseWriter)(nil))] = []reflect.Type{
+		reflect.ValueOf((*_netHTTPResponseWriterHijacker)(nil)).Type().Elem(),
+	}
+	MapTypes[reflect.ValueOf((*_io_Reader)(nil))] = []reflect.Type{
+		reflect.ValueOf((*_ioReaderWriteTo)(nil)).Type().Elem(),
+	}
+	MapTypes[reflect.ValueOf((*_io_Writer)(nil))] = []reflect.Type{
+		reflect.ValueOf((*_ioWriterReadFrom)(nil)).Type().Elem(),
+	}
+}