Added sort keys operator

pkg/yqlib/operator_sort_keys.go

@@ -0,0 +1,53 @@
+package yqlib
+
+import (
+	"container/list"
+	"sort"
+
+	yaml "gopkg.in/yaml.v3"
+)
+
+func SortKeysOperator(d *dataTreeNavigator, matchingNodes *list.List, pathNode *PathTreeNode) (*list.List, error) {
+
+	for el := matchingNodes.Front(); el != nil; el = el.Next() {
+		candidate := el.Value.(*CandidateNode)
+		rhs, err := d.GetMatchingNodes(nodeToMap(candidate), pathNode.Rhs)
+		if err != nil {
+			return nil, err
+		}
+
+		for childEl := rhs.Front(); childEl != nil; childEl = childEl.Next() {
+			node := UnwrapDoc(childEl.Value.(*CandidateNode).Node)
+			if node.Kind == yaml.MappingNode {
+				sortKeys(node)
+			}
+			if err != nil {
+				return nil, err
+			}
+		}
+
+	}
+	return matchingNodes, nil
+}
+
+func sortKeys(node *yaml.Node) {
+	keys := make([]string, len(node.Content)/2)
+	keyBucket := map[string]*yaml.Node{}
+	valueBucket := map[string]*yaml.Node{}
+	var contents = node.Content
+	for index := 0; index < len(contents); index = index + 2 {
+		key := contents[index]
+		value := contents[index+1]
+		keys[index/2] = key.Value
+		keyBucket[key.Value] = key
+		valueBucket[key.Value] = value
+	}
+	sort.Strings(keys)
+	sortedContent := make([]*yaml.Node, len(node.Content))
+	for index := 0; index < len(keys); index = index + 1 {
+		keyString := keys[index]
+		sortedContent[index*2] = keyBucket[keyString]
+		sortedContent[1+(index*2)] = valueBucket[keyString]
+	}
+	node.Content = sortedContent
+}