kyaml: initial support for yaml and resource manipulation

kyaml/yaml/walk/associative_sequence.go

@@ -0,0 +1,128 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import (
+	"strings"
+
+	"github.com/go-errors/errors"
+	"sigs.k8s.io/kustomize/kyaml/sets"
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+func (l *Walker) walkAssociativeSequence() (*yaml.RNode, error) {
+
+	// may require initializing the dest node
+	dest, err := l.Sources.setDestNode(l.VisitList(l.Sources, AssociativeList))
+	if dest == nil || err != nil {
+		return nil, err
+	}
+
+	// find the list of elements we need to recursively walk
+	key, err := l.elementKey()
+	if err != nil {
+		return nil, err
+	}
+	values, err := l.elementValues(key)
+	if err != nil {
+		return nil, err
+	}
+
+	// recursively set the elements in the list
+	for _, value := range values {
+		val, err := Walker{Visitor: l,
+			Sources: l.elementValue(key, value)}.Walk()
+		if err != nil {
+			return nil, err
+		}
+		if yaml.IsEmpty(val) {
+			_, err = dest.Pipe(yaml.ElementSetter{Key: key, Value: value})
+			if err != nil {
+				return nil, err
+			}
+			continue
+		}
+
+		if val.Field(key) == nil {
+			// make sure the key is set on the field
+			_, err = val.Pipe(yaml.SetField(key, yaml.NewScalarRNode(value)))
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		// this handles empty and non-empty values
+		_, err = dest.Pipe(yaml.ElementSetter{Element: val.YNode(), Key: key, Value: value})
+		if err != nil {
+			return nil, err
+		}
+	}
+	// field is empty
+	if yaml.IsEmpty(dest) {
+		return nil, nil
+	}
+	return dest, nil
+}
+
+// elementKey returns the merge key to use for the associative list
+func (l Walker) elementKey() (string, error) {
+	var key string
+	for i := range l.Sources {
+		if l.Sources[i] != nil && len(l.Sources[i].Content()) > 0 {
+			newKey := l.Sources[i].GetAssociativeKey()
+			if key != "" && key != newKey {
+				return "", errors.Errorf(
+					"conflicting merge keys [%s,%s] for field %s",
+					key, newKey, strings.Join(l.Path, "."))
+			}
+			key = newKey
+		}
+	}
+	if key == "" {
+		return "", errors.Errorf("no merge key found for field %s",
+			strings.Join(l.Path, "."))
+	}
+	return key, nil
+}
+
+// elementValues returns a slice containing all values for the field across all elements
+// from all sources.
+// Return value slice is ordered using the original ordering from the elements, where
+// elements missing from earlier sources appear later.
+func (l Walker) elementValues(key string) ([]string, error) {
+	// use slice to to keep elements in the original order
+	// dest node must be first
+	var returnValues []string
+	seen := sets.String{}
+	for i := range l.Sources {
+		if l.Sources[i] == nil {
+			continue
+		}
+
+		// add the value of the field for each element
+		// don't check error, we know this is a list node
+		values, _ := l.Sources[i].ElementValues(key)
+		for _, s := range values {
+			if seen.Has(s) {
+				continue
+			}
+			returnValues = append(returnValues, s)
+			seen.Insert(s)
+		}
+	}
+	return returnValues, nil
+}
+
+// fieldValue returns a slice containing each source's value for fieldName
+func (l Walker) elementValue(key, value string) []*yaml.RNode {
+	var fields []*yaml.RNode
+	for i := range l.Sources {
+		if l.Sources[i] == nil {
+			fields = append(fields, nil)
+			continue
+		}
+		fields = append(fields, l.Sources[i].Element(key, value))
+	}
+	return fields
+}