fix lint warning (#242)

* fix lint warning - exported func NewStreamVisitor returns unexported type *command.streamVisitor, which can be annoying to use

* add comment for StreamVisitor struct

* golang 1.17 : go:build style

cmd/client/command/visitor.go

@@ -22,13 +22,14 @@ type spec struct {
  doc string
 }
 
-type streamVisitor struct {
+// StreamVisitor is the struct of Visitor Pattern
+type StreamVisitor struct {
  io.Reader
 }
 
 // NewStreamVisitor returns a streamVisitor.
-func NewStreamVisitor(src string) *streamVisitor {
- return &streamVisitor{
+func NewStreamVisitor(src string) *StreamVisitor {
+ return &StreamVisitor{
  Reader: strings.NewReader(src),
  }
 }
@@ -58,7 +59,7 @@ func (d *yamlDecoder) Decode(into interface{}) error {
 }
 
 // Visit implements Visitor over a stream.
-func (v *streamVisitor) Visit(fn VisitorFunc) {
+func (v *StreamVisitor) Visit(fn VisitorFunc) {
  d := newYAMLDecoder(v.Reader)
  var validSpecs []spec
  for {

pkg/api/wasm.go

@@ -1,3 +1,4 @@
+//go:build wasmhost
 // +build wasmhost
 
 /*

pkg/common/os_test.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 /*

pkg/common/signal_unix.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 /*

pkg/common/signal_unix_test.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 /*

pkg/common/signal_windows.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 /*

pkg/common/time_unix.go

@@ -1,3 +1,4 @@
+//go:build !windows
 // +build !windows
 
 /*

pkg/common/time_windows.go

@@ -1,3 +1,4 @@
+//go:build windows
 // +build windows
 
 /*

pkg/filter/wasmhost/hostfunc.go

@@ -1,3 +1,4 @@
+//go:build wasmhost
 // +build wasmhost
 
 /*

pkg/filter/wasmhost/vm.go

@@ -1,3 +1,4 @@
+//go:build wasmhost
 // +build wasmhost
 
 /*

pkg/filter/wasmhost/wasmhost.go

@@ -1,3 +1,4 @@
+//go:build wasmhost
 // +build wasmhost
 
 /*