Separate implementation of fieldset from validation

Author: Antoine Pelisse

typed/tofieldset.go

@@ -0,0 +1,164 @@
+/*
+Copyright 2018 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 typed
+
+import (
+	"sync"
+
+	"sigs.k8s.io/structured-merge-diff/fieldpath"
+	"sigs.k8s.io/structured-merge-diff/schema"
+	"sigs.k8s.io/structured-merge-diff/value"
+)
+
+var tPool = sync.Pool{
+	New: func() interface{} { return &toFieldSetWalker{} },
+}
+
+func (tv TypedValue) toFieldSetWalker() *toFieldSetWalker {
+	v := tPool.Get().(*toFieldSetWalker)
+	v.value = tv.value
+	v.schema = tv.schema
+	v.typeRef = tv.typeRef
+	v.set = &fieldpath.Set{}
+	return v
+}
+
+func (v *toFieldSetWalker) finished() {
+	v.schema = nil
+	v.typeRef = schema.TypeRef{}
+	v.path = nil
+	v.set = nil
+	tPool.Put(v)
+}
+
+type toFieldSetWalker struct {
+	value   value.Value
+	schema  *schema.Schema
+	typeRef schema.TypeRef
+
+	set  *fieldpath.Set
+	path fieldpath.Path
+
+	// Allocate only as many walkers as needed for the depth by storing them here.
+	spareWalkers *[]*toFieldSetWalker
+}
+
+func (v *toFieldSetWalker) prepareDescent(pe fieldpath.PathElement, tr schema.TypeRef) *toFieldSetWalker {
+	if v.spareWalkers == nil {
+		// first descent.
+		v.spareWalkers = &[]*toFieldSetWalker{}
+	}
+	var v2 *toFieldSetWalker
+	if n := len(*v.spareWalkers); n > 0 {
+		v2, *v.spareWalkers = (*v.spareWalkers)[n-1], (*v.spareWalkers)[:n-1]
+	} else {
+		v2 = &toFieldSetWalker{}
+	}
+	*v2 = *v
+	v2.typeRef = tr
+	v2.path = append(v2.path, pe)
+	return v2
+}
+
+func (v *toFieldSetWalker) finishDescent(v2 *toFieldSetWalker) {
+	// if the descent caused a realloc, ensure that we reuse the buffer
+	// for the next sibling.
+	v.path = v2.path[:len(v2.path)-1]
+	*v.spareWalkers = append(*v.spareWalkers, v2)
+}
+
+func (v *toFieldSetWalker) toFieldSet() ValidationErrors {
+	return resolveSchema(v.schema, v.typeRef, &v.value, v)
+}
+
+func (v *toFieldSetWalker) doScalar(t *schema.Scalar) ValidationErrors {
+	v.set.Insert(v.path)
+
+	return nil
+}
+
+func (v *toFieldSetWalker) visitListItems(t *schema.List, list []interface{}) (errs ValidationErrors) {
+	for i, child := range list {
+		pe, _ := listItemToPathElement(t, i, child)
+		v2 := v.prepareDescent(pe, t.ElementType)
+		v2.value = child
+		errs = append(errs, v2.toFieldSet()...)
+
+		v2.set.Insert(v2.path)
+		v.finishDescent(v2)
+	}
+	return errs
+}
+
+func (v *toFieldSetWalker) doList(t *schema.List) (errs ValidationErrors) {
+	list, _ := listValue(v.value)
+
+	if t.ElementRelationship == schema.Atomic {
+		v.set.Insert(v.path)
+		return nil
+	}
+
+	if list == nil {
+		return nil
+	}
+
+	errs = v.visitListItems(t, list)
+
+	return errs
+}
+
+func (v *toFieldSetWalker) visitMapItems(t *schema.Map, m map[string]interface{}) (errs ValidationErrors) {
+	for key, val := range m {
+		k := key
+		pe := fieldpath.PathElement{FieldName: &k}
+
+		tr := t.ElementType
+		if sf, ok := t.FindField(key); ok {
+			tr = sf.Type
+		}
+		v2 := v.prepareDescent(pe, tr)
+		v2.value = val
+		errs = append(errs, v2.toFieldSet()...)
+		if _, ok := t.FindField(key); !ok {
+			v2.set.Insert(v2.path)
+		}
+		v.finishDescent(v2)
+
+	}
+	return errs
+}
+
+func (v *toFieldSetWalker) doMap(t *schema.Map) (errs ValidationErrors) {
+	m, _ := mapValue(v.value)
+
+	if t.ElementRelationship == schema.Atomic {
+		v.set.Insert(v.path)
+		return nil
+	}
+
+	if m == nil {
+		return nil
+	}
+
+	errs = v.visitMapItems(t, m)
+
+	return errs
+}
+
+func (v *toFieldSetWalker) errorf(string, ...interface{}) ValidationErrors {
+	return nil
+}

typed/typed.go

@@ -79,15 +79,12 @@ func (tv TypedValue) Validate() error {
 // ToFieldSet creates a set containing every leaf field and item mentioned, or
 // validation errors, if any were encountered.
 func (tv TypedValue) ToFieldSet() (*fieldpath.Set, error) {
-	s := fieldpath.NewSet()
-	w := tv.walker()
+	w := tv.toFieldSetWalker()
 	defer w.finished()
-	w.leafFieldCallback = func(p fieldpath.Path) { s.Insert(p) }
-	w.nodeFieldCallback = func(p fieldpath.Path) { s.Insert(p) }
-	if errs := w.validate(); len(errs) != 0 {
+	if errs := w.toFieldSet(); len(errs) != 0 {
 		return nil, errs
 	}
-	return s, nil
+	return w.set, nil
 }
 
 // Merge returns the result of merging tv and pso ("partially specified