omit operator (#1989)

pkg/yqlib/operator_omit.go

@@ -0,0 +1,73 @@
+package yqlib
+
+import (
+	"container/list"
+	"strconv"
+)
+
+func omitMap(original *CandidateNode, indices *CandidateNode) *CandidateNode {
+	filteredContent := make([]*CandidateNode, 0, max(0, len(original.Content)-len(indices.Content)*2))
+
+	for index := 0; index < len(original.Content); index += 2 {
+		pos := findInArray(indices, original.Content[index])
+		if pos < 0 {
+			clonedKey := original.Content[index].Copy()
+			clonedValue := original.Content[index+1].Copy()
+			filteredContent = append(filteredContent, clonedKey, clonedValue)
+		}
+	}
+	result := original.CopyWithoutContent()
+	result.AddChildren(filteredContent)
+	return result
+}
+
+func omitSequence(original *CandidateNode, indices *CandidateNode) *CandidateNode {
+	filteredContent := make([]*CandidateNode, 0, max(0, len(original.Content)-len(indices.Content)))
+
+	for index := 0; index < len(original.Content); index++ {
+		pos := findInArray(indices, createScalarNode(index, strconv.Itoa(index)))
+		if pos < 0 {
+			filteredContent = append(filteredContent, original.Content[index].Copy())
+		}
+	}
+	result := original.CopyWithoutContent()
+	result.AddChildren(filteredContent)
+	return result
+}
+
+func omitOperator(d *dataTreeNavigator, context Context, expressionNode *ExpressionNode) (Context, error) {
+	log.Debugf("Omit")
+
+	contextIndicesToOmit, err := d.GetMatchingNodes(context, expressionNode.RHS)
+
+	if err != nil {
+		return Context{}, err
+	}
+	indicesToOmit := &CandidateNode{}
+	if contextIndicesToOmit.MatchingNodes.Len() > 0 {
+		indicesToOmit = contextIndicesToOmit.MatchingNodes.Front().Value.(*CandidateNode)
+	}
+	if len(indicesToOmit.Content) == 0 {
+		log.Debugf("No omit indices specified")
+		return context, nil
+	}
+	var results = list.New()
+
+	for el := context.MatchingNodes.Front(); el != nil; el = el.Next() {
+		node := el.Value.(*CandidateNode)
+
+		var replacement *CandidateNode
+
+		if node.Kind == MappingNode {
+			replacement = omitMap(node, indicesToOmit)
+		} else if node.Kind == SequenceNode {
+			replacement = omitSequence(node, indicesToOmit)
+		} else {
+			log.Debugf("Omit from type %v (%v) is noop", node.Tag, node.GetNicePath())
+			return context, nil
+		}
+		replacement.LeadingContent = node.LeadingContent
+		results.PushBack(replacement)
+	}
+	return context.ChildContext(results), nil
+}