apiextensions: add structural schema visitor

staging/src/k8s.io/apiextensions-apiserver/pkg/apiserver/schema/visitor.go

@@ -0,0 +1,106 @@
+/*
+Copyright 2019 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 schema
+
+// Visitor recursively walks through a structural schema.
+type Visitor struct {
+	// Structural is called on each Structural node in the schema, before recursing into
+	// the subtrees. It is allowed to mutate s. Return true if something has been changed.
+	// +optional
+	Structural func(s *Structural) bool
+	// NestedValueValidation is called on each NestedValueValidation node in the schema,
+	// before recursing into subtrees. It is allowed to mutate vv. Return true if something
+	// has been changed.
+	// +optional
+	NestedValueValidation func(vv *NestedValueValidation) bool
+}
+
+// Visit recursively walks through the structural schema and calls the given callbacks
+// at each node of those types.
+func (m *Visitor) Visit(s *Structural) {
+	m.visitStructural(s)
+}
+
+func (m *Visitor) visitStructural(s *Structural) bool {
+	ret := false
+	if m.Structural != nil {
+		ret = m.Structural(s)
+	}
+
+	if s.Items != nil {
+		m.visitStructural(s.Items)
+	}
+	for k, v := range s.Properties {
+		if changed := m.visitStructural(&v); changed {
+			ret = true
+			s.Properties[k] = v
+		}
+	}
+	if s.Generic.AdditionalProperties != nil && s.Generic.AdditionalProperties.Structural != nil {
+		m.visitStructural(s.Generic.AdditionalProperties.Structural)
+	}
+	if s.ValueValidation != nil {
+		for i := range s.ValueValidation.AllOf {
+			m.visitNestedValueValidation(&s.ValueValidation.AllOf[i])
+		}
+		for i := range s.ValueValidation.AnyOf {
+			m.visitNestedValueValidation(&s.ValueValidation.AnyOf[i])
+		}
+		for i := range s.ValueValidation.OneOf {
+			m.visitNestedValueValidation(&s.ValueValidation.OneOf[i])
+		}
+		if s.ValueValidation.Not != nil {
+			m.visitNestedValueValidation(s.ValueValidation.Not)
+		}
+	}
+
+	return ret
+}
+
+func (m *Visitor) visitNestedValueValidation(vv *NestedValueValidation) bool {
+	ret := false
+	if m.NestedValueValidation != nil {
+		ret = m.NestedValueValidation(vv)
+	}
+
+	if vv.Items != nil {
+		m.visitNestedValueValidation(vv.Items)
+	}
+	for k, v := range vv.Properties {
+		if changed := m.visitNestedValueValidation(&v); changed {
+			ret = true
+			vv.Properties[k] = v
+		}
+	}
+	if vv.ForbiddenGenerics.AdditionalProperties != nil && vv.ForbiddenGenerics.AdditionalProperties.Structural != nil {
+		m.visitStructural(vv.ForbiddenGenerics.AdditionalProperties.Structural)
+	}
+	for i := range vv.ValueValidation.AllOf {
+		m.visitNestedValueValidation(&vv.ValueValidation.AllOf[i])
+	}
+	for i := range vv.ValueValidation.AnyOf {
+		m.visitNestedValueValidation(&vv.ValueValidation.AnyOf[i])
+	}
+	for i := range vv.ValueValidation.OneOf {
+		m.visitNestedValueValidation(&vv.ValueValidation.OneOf[i])
+	}
+	if vv.ValueValidation.Not != nil {
+		m.visitNestedValueValidation(vv.ValueValidation.Not)
+	}
+
+	return ret
+}