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|
package yaml_utils
import (
"errors"
"fmt"
"gopkg.in/yaml.v3"
)
// takes a yaml document in bytes, a path to a key, and a value to set. The value must be a scalar.
func UpdateYamlValue(yamlBytes []byte, path []string, value string) ([]byte, error) {
// Parse the YAML file.
var node yaml.Node
err := yaml.Unmarshal(yamlBytes, &node)
if err != nil {
return nil, fmt.Errorf("failed to parse YAML: %w", err)
}
// Empty document: need to create the top-level map ourselves
if len(node.Content) == 0 {
node.Content = append(node.Content, &yaml.Node{
Kind: yaml.MappingNode,
})
}
body := node.Content[0]
if body.Kind != yaml.MappingNode {
return yamlBytes, errors.New("yaml document is not a dictionary")
}
if didChange, err := updateYamlNode(body, path, value); err != nil || !didChange {
return yamlBytes, err
}
// Convert the updated YAML node back to YAML bytes.
updatedYAMLBytes, err := yaml.Marshal(body)
if err != nil {
return nil, fmt.Errorf("failed to convert YAML node to bytes: %w", err)
}
return updatedYAMLBytes, nil
}
// Recursive function to update the YAML node.
func updateYamlNode(node *yaml.Node, path []string, value string) (bool, error) {
if len(path) == 0 {
if node.Kind != yaml.ScalarNode {
return false, errors.New("yaml node is not a scalar")
}
if node.Value != value {
node.Value = value
return true, nil
}
return false, nil
}
if node.Kind != yaml.MappingNode {
return false, errors.New("yaml node in path is not a dictionary")
}
key := path[0]
if _, valueNode := lookupKey(node, key); valueNode != nil {
return updateYamlNode(valueNode, path[1:], value)
}
// if the key doesn't exist, we'll add it
// at end of path: add the new key, done
if len(path) == 1 {
node.Content = append(node.Content, &yaml.Node{
Kind: yaml.ScalarNode,
Value: key,
}, &yaml.Node{
Kind: yaml.ScalarNode,
Value: value,
})
return true, nil
}
// otherwise, create the missing intermediate node and continue
newNode := &yaml.Node{
Kind: yaml.MappingNode,
}
node.Content = append(node.Content, &yaml.Node{
Kind: yaml.ScalarNode,
Value: key,
}, newNode)
return updateYamlNode(newNode, path[1:], value)
}
func lookupKey(node *yaml.Node, key string) (*yaml.Node, *yaml.Node) {
for i := 0; i < len(node.Content)-1; i += 2 {
if node.Content[i].Value == key {
return node.Content[i], node.Content[i+1]
}
}
return nil, nil
}
// takes a yaml document in bytes, a path to a key, and a new name for the key.
// Will rename the key to the new name if it exists, and do nothing otherwise.
func RenameYamlKey(yamlBytes []byte, path []string, newKey string) ([]byte, error) {
// Parse the YAML file.
var node yaml.Node
err := yaml.Unmarshal(yamlBytes, &node)
if err != nil {
return nil, fmt.Errorf("failed to parse YAML: %w", err)
}
// Empty document: nothing to do.
if len(node.Content) == 0 {
return yamlBytes, nil
}
body := node.Content[0]
if didRename, err := renameYamlKey(body, path, newKey); err != nil || !didRename {
return yamlBytes, err
}
// Convert the updated YAML node back to YAML bytes.
updatedYAMLBytes, err := yaml.Marshal(body)
if err != nil {
return nil, fmt.Errorf("failed to convert YAML node to bytes: %w", err)
}
return updatedYAMLBytes, nil
}
// Recursive function to rename the YAML key.
func renameYamlKey(node *yaml.Node, path []string, newKey string) (bool, error) {
if node.Kind != yaml.MappingNode {
return false, errors.New("yaml node in path is not a dictionary")
}
keyNode, valueNode := lookupKey(node, path[0])
if keyNode == nil {
return false, nil
}
// end of path reached: rename key
if len(path) == 1 {
// Check that new key doesn't exist yet
if newKeyNode, _ := lookupKey(node, newKey); newKeyNode != nil {
return false, fmt.Errorf("new key `%s' already exists", newKey)
}
keyNode.Value = newKey
return true, nil
}
return renameYamlKey(valueNode, path[1:], newKey)
}
// Traverses a yaml document, calling the callback function for each node. The
// callback is allowed to modify the node in place, in which case it should
// return true. The function returns the original yaml document if none of the
// callbacks returned true, and the modified document otherwise.
func Walk(yamlBytes []byte, callback func(node *yaml.Node, path string) bool) ([]byte, error) {
// Parse the YAML file.
var node yaml.Node
err := yaml.Unmarshal(yamlBytes, &node)
if err != nil {
return nil, fmt.Errorf("failed to parse YAML: %w", err)
}
// Empty document: nothing to do.
if len(node.Content) == 0 {
return yamlBytes, nil
}
body := node.Content[0]
if didChange, err := walk(body, "", callback); err != nil || !didChange {
return yamlBytes, err
}
// Convert the updated YAML node back to YAML bytes.
updatedYAMLBytes, err := yaml.Marshal(body)
if err != nil {
return nil, fmt.Errorf("failed to convert YAML node to bytes: %w", err)
}
return updatedYAMLBytes, nil
}
func walk(node *yaml.Node, path string, callback func(*yaml.Node, string) bool) (bool, error) {
didChange := callback(node, path)
switch node.Kind {
case yaml.DocumentNode:
return false, fmt.Errorf("Unexpected document node in the middle of a yaml tree")
case yaml.MappingNode:
for i := 0; i < len(node.Content); i += 2 {
name := node.Content[i].Value
childNode := node.Content[i+1]
var childPath string
if path == "" {
childPath = name
} else {
childPath = fmt.Sprintf("%s.%s", path, name)
}
didChangeChild, err := walk(childNode, childPath, callback)
if err != nil {
return false, err
}
didChange = didChange || didChangeChild
}
case yaml.SequenceNode:
for i := 0; i < len(node.Content); i++ {
childPath := fmt.Sprintf("%s[%d]", path, i)
didChangeChild, err := walk(node.Content[i
|
