Rewrite kubectl explain to use openapi

This removes all dependencies on swagger 1.2 for explain.

pkg/kubectl/explain/recursive_fields_printer.go

@@ -0,0 +1,77 @@
+/*
+Copyright 2017 The Kubernetes 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 explain
+
+import (
+	"k8s.io/kubernetes/pkg/kubectl/cmd/util/openapi"
+)
+
+// indentPerLevel is the level of indentation for each field recursion.
+const indentPerLevel = 3
+
+// recursiveFieldsPrinter recursively prints all the fields for a given
+// schema.
+type recursiveFieldsPrinter struct {
+	Writer *Formatter
+	Error  error
+}
+
+var _ openapi.SchemaVisitor = &recursiveFieldsPrinter{}
+var _ fieldsPrinter = &recursiveFieldsPrinter{}
+
+// VisitArray is just a passthrough.
+func (f *recursiveFieldsPrinter) VisitArray(a *openapi.Array) {
+	a.SubType.Accept(f)
+}
+
+// VisitKind prints all its fields with their type, and then recurses
+// inside each of these (pre-order).
+func (f *recursiveFieldsPrinter) VisitKind(k *openapi.Kind) {
+	for _, key := range k.Keys() {
+		v := k.Fields[key]
+		f.Writer.Write("%s\t<%s>", key, GetTypeName(v))
+		subFields := &recursiveFieldsPrinter{
+			Writer: f.Writer.Indent(indentPerLevel),
+		}
+		if err := subFields.PrintFields(v); err != nil {
+			f.Error = err
+			return
+		}
+	}
+}
+
+// VisitMap is just a passthrough.
+func (f *recursiveFieldsPrinter) VisitMap(m *openapi.Map) {
+	m.SubType.Accept(f)
+}
+
+// VisitPrimitive does nothing, since it doesn't have sub-fields.
+func (f *recursiveFieldsPrinter) VisitPrimitive(p *openapi.Primitive) {
+	// Nothing to do.
+}
+
+// VisitReference is just a passthrough.
+func (f *recursiveFieldsPrinter) VisitReference(r openapi.Reference) {
+	r.SubSchema().Accept(f)
+}
+
+// PrintFields will recursively print all the fields for the given
+// schema.
+func (f *recursiveFieldsPrinter) PrintFields(schema openapi.Schema) error {
+	schema.Accept(f)
+	return f.Error
+}