func ParseToLabelSelector(selector string) (*LabelSelector, error) {
	reqs, err := labels.ParseToRequirements(selector)
	if err != nil {
		return nil, fmt.Errorf("couldn't parse the selector string \"%s\": %v", selector, err)
	}
	labelSelector := &LabelSelector{
		MatchLabels:      map[string]string{},
		MatchExpressions: []LabelSelectorRequirement{},
	}
	for _, req := range reqs {
		var op LabelSelectorOperator
		switch req.Operator() {
		case selection.Equals, selection.DoubleEquals:
			vals := req.Values()
			if vals.Len() != 1 {
				return nil, fmt.Errorf("equals operator must have exactly one value")
			}
			val, ok := vals.PopAny()
			if !ok {
				return nil, fmt.Errorf("equals operator has exactly one value but it cannot be retrieved")
			}
			labelSelector.MatchLabels[req.Key()] = val
			continue
		case selection.In:
			op = LabelSelectorOpIn
		case selection.NotIn:
			op = LabelSelectorOpNotIn
		case selection.Exists:
			op = LabelSelectorOpExists
		case selection.DoesNotExist:
			op = LabelSelectorOpDoesNotExist
		case selection.GreaterThan, selection.LessThan:
			return nil, fmt.Errorf("%q isn't supported in label selectors", req.Operator())
		default:
			return nil, fmt.Errorf("%q is not a valid label selector operator", req.Operator())
		}
		labelSelector.MatchExpressions = append(labelSelector.MatchExpressions, LabelSelectorRequirement{
			Key:      req.Key(),
			Operator: op,
			Values:   req.Values().List(),
		})
	}
	return labelSelector, nil
}
ParseToLabelSelector parses a string representing a selector into a LabelSelector object.
Note: This function should be kept in sync with the parser in pkg/labels/selector.go
package v1
import (
	"encoding/json"
	"fmt"
	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/selection"
	"k8s.io/apimachinery/pkg/types"
)
func LabelSelectorAsSelector(ps *LabelSelector) (labels.Selector, error) {
	if ps == nil {
		return labels.Nothing(), nil
	}
	if len(ps.MatchLabels)+len(ps.MatchExpressions) == 0 {
		return labels.Everything(), nil
	}
	selector := labels.NewSelector()
	for k, v := range ps.MatchLabels {
		r, err := labels.NewRequirement(k, selection.Equals, []string{v})
		if err != nil {
			return nil, err
		}
		selector = selector.Add(*r)
	}
	for _, expr := range ps.MatchExpressions {
		var op selection.Operator
		switch expr.Operator {
		case LabelSelectorOpIn:
			op = selection.In
		case LabelSelectorOpNotIn:
			op = selection.NotIn
		case LabelSelectorOpExists:
			op = selection.Exists
		case LabelSelectorOpDoesNotExist:
			op = selection.DoesNotExist
		default:
			return nil, fmt.Errorf("%q is not a valid pod selector operator", expr.Operator)
		}
		r, err := labels.NewRequirement(expr.Key, op, append([]string(nil), expr.Values...))
		if err != nil {
			return nil, err
		}
		selector = selector.Add(*r)
	}
	return selector, nil
}
func LabelSelectorAsMap(ps *LabelSelector) (map[string]string, error) {
	if ps == nil {
		return nil, nil
	}
	selector := map[string]string{}
	for k, v := range ps.MatchLabels {
		selector[k] = v
	}
	for _, expr := range ps.MatchExpressions {
		switch expr.Operator {
		case LabelSelectorOpIn:
			if len(expr.Values) != 1 {
				return selector, fmt.Errorf("operator %q without a single value cannot be converted into the old label selector format", expr.Operator)
			}
			selector[expr.Key] = expr.Values[0]
		case LabelSelectorOpNotIn, LabelSelectorOpExists, LabelSelectorOpDoesNotExist:
			return selector, fmt.Errorf("operator %q cannot be converted into the old label selector format", expr.Operator)
		default:
			return selector, fmt.Errorf("%q is not a valid selector operator", expr.Operator)
		}
	}
	return selector, nil
}