Added decoder op

pkg/yqlib/operator_encoder_decoder.go

@@ -0,0 +1,62 @@
+package yqlib
+
+import (
+	"bufio"
+	"bytes"
+	"container/list"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+func yamlToString(candidate *CandidateNode, prefs encoderPreferences) (string, error) {
+	var output bytes.Buffer
+	printer := NewPrinter(bufio.NewWriter(&output), prefs.format, true, false, 2, true)
+	elMap := list.New()
+	elMap.PushBack(candidate)
+	err := printer.PrintResults(elMap)
+	return output.String(), err
+}
+
+type encoderPreferences struct {
+	format PrinterOutputFormat
+}
+
+/* encodes object as yaml string */
+
+func encodeOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	preferences := expressionNode.Operation.Preferences.(encoderPreferences)
+	var results = list.New()
+	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
+		candidate := el.Value.(*CandidateNode)
+		stringValue, err := yamlToString(candidate, preferences)
+		if err != nil {
+			return Context{}, err
+		}
+
+		stringContentNode := &yaml.Node{Kind: yaml.ScalarNode, Tag: "!!str", Value: stringValue}
+		results.PushBack(candidate.CreateChild(nil, stringContentNode))
+	}
+	return context.ChildContext(results), nil
+}
+
+/* takes a string and decodes it back into an object */
+func decodeOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+
+	var results = list.New()
+	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
+		candidate := el.Value.(*CandidateNode)
+		var dataBucket yaml.Node
+		log.Debugf("got: [%v]", candidate.Node.Value)
+		decoder := yaml.NewDecoder(strings.NewReader(unwrapDoc(candidate.Node).Value))
+		errorReading := decoder.Decode(&dataBucket)
+		if errorReading != nil {
+			return Context{}, errorReading
+		}
+		//first node is a doc
+		node := unwrapDoc(&dataBucket)
+
+		results.PushBack(candidate.CreateChild(nil, node))
+	}
+	return context.ChildContext(results), nil
+}