kyaml: initial support for yaml and resource manipulation

kyaml/yaml/walk/walk.go

@@ -0,0 +1,144 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package walk
+
+import (
+	"fmt"
+	"os"
+	"strings"
+
+	"sigs.k8s.io/kustomize/kyaml/yaml"
+)
+
+// Filter walks the Source RNode and modifies the RNode provided to GrepFilter.
+type Walker struct {
+	// Visitor is invoked by GrepFilter
+	Visitor
+
+	// Source is the RNode to walk.  All Source fields and associative list elements
+	// will be visited.
+	Sources Sources
+
+	// Path is the field path to the current Source Node.
+	Path []string
+}
+
+func (l Walker) Kind() yaml.Kind {
+	for _, s := range l.Sources {
+		if !yaml.IsEmpty(s) {
+			return s.YNode().Kind
+		}
+	}
+	return 0
+}
+
+// GrepFilter implements yaml.GrepFilter
+func (l Walker) Walk() (*yaml.RNode, error) {
+	// invoke the handler for the corresponding node type
+	switch l.Kind() {
+	case yaml.MappingNode:
+		if err := yaml.ErrorIfAnyInvalidAndNonNull(yaml.MappingNode, l.Sources...); err != nil {
+			return nil, err
+		}
+		return l.walkMap()
+	case yaml.SequenceNode:
+		if err := yaml.ErrorIfAnyInvalidAndNonNull(yaml.SequenceNode, l.Sources...); err != nil {
+			return nil, err
+		}
+		if yaml.IsAssociative(l.Sources) {
+			return l.walkAssociativeSequence()
+		} else {
+			return l.walkNonAssociativeSequence()
+		}
+	case yaml.ScalarNode:
+		if err := yaml.ErrorIfAnyInvalidAndNonNull(yaml.ScalarNode, l.Sources...); err != nil {
+			return nil, err
+		}
+		return l.walkScalar()
+	case 0:
+		// walk empty nodes as maps
+		return l.walkMap()
+	default:
+		return nil, nil
+	}
+}
+
+const (
+	DestIndex = iota
+	OriginIndex
+	UpdatedIndex
+)
+
+type Sources []*yaml.RNode
+
+// Dest returns the destination node
+func (s Sources) Dest() *yaml.RNode {
+	if len(s) <= DestIndex {
+		return nil
+	}
+	return s[DestIndex]
+}
+
+// Origin returns the origin node
+func (s Sources) Origin() *yaml.RNode {
+	if len(s) <= OriginIndex {
+		return nil
+	}
+	return s[OriginIndex]
+}
+
+// Updated returns the updated node
+func (s Sources) Updated() *yaml.RNode {
+	if len(s) <= UpdatedIndex {
+		return nil
+	}
+	return s[UpdatedIndex]
+}
+
+func (s Sources) String() string {
+	var values []string
+	for i := range s {
+		str, err := s[i].String()
+		if err != nil {
+			fmt.Fprintf(os.Stderr, "%v\n", err)
+		}
+		values = append(values, str)
+	}
+	return strings.Join(values, "\n")
+}
+
+// setDestNode sets the destination source node
+func (s Sources) setDestNode(node *yaml.RNode, err error) (*yaml.RNode, error) {
+	if err != nil {
+		return nil, err
+	}
+	s[0] = node
+	return node, nil
+}
+
+type FieldSources []*yaml.MapNode
+
+// Dest returns the destination node
+func (s FieldSources) Dest() *yaml.MapNode {
+	if len(s) <= DestIndex {
+		return nil
+	}
+	return s[DestIndex]
+}
+
+// Origin returns the origin node
+func (s FieldSources) Origin() *yaml.MapNode {
+	if len(s) <= OriginIndex {
+		return nil
+	}
+	return s[OriginIndex]
+}
+
+// Updated returns the updated node
+func (s FieldSources) Updated() *yaml.MapNode {
+	if len(s) <= UpdatedIndex {
+		return nil
+	}
+	return s[UpdatedIndex]
+}