yq/pkg/yqlib/treeops/data_tree_navigator.go

package treeops

import (
	"fmt"

	"container/list"

	"gopkg.in/op/go-logging.v1"
)

type dataTreeNavigator struct {
	navigationPrefs NavigationPrefs
}

type NavigationPrefs struct {
	FollowAlias bool
}

type DataTreeNavigator interface {
	GetMatchingNodes(matchingNodes []*CandidateNode, pathNode *PathTreeNode) ([]*CandidateNode, error)
}

func NewDataTreeNavigator(navigationPrefs NavigationPrefs) DataTreeNavigator {
	return &dataTreeNavigator{navigationPrefs}
}

func (d *dataTreeNavigator) GetMatchingNodes(matchingNodes []*CandidateNode, pathNode *PathTreeNode) ([]*CandidateNode, error) {
	var matchingNodeMap = list.New()

	for _, n := range matchingNodes {
		matchingNodeMap.PushBack(n)
	}

	matchedNodes, err := d.getMatchingNodes(matchingNodeMap, pathNode)
	if err != nil {
		return nil, err
	}

	values := make([]*CandidateNode, 0, matchedNodes.Len())

	for el := matchedNodes.Front(); el != nil; el = el.Next() {
		values = append(values, el.Value.(*CandidateNode))
	}
	return values, nil
}

func (d *dataTreeNavigator) getMatchingNodes(matchingNodes *list.List, pathNode *PathTreeNode) (*list.List, error) {
	if pathNode == nil {
		log.Debugf("getMatchingNodes - nothing to do")
		return matchingNodes, nil
	}
	log.Debugf("Processing Op: %v", pathNode.Operation.toString())
	if log.IsEnabledFor(logging.DEBUG) {
		for el := matchingNodes.Front(); el != nil; el = el.Next() {
			log.Debug(NodeToString(el.Value.(*CandidateNode)))
		}
	}
	log.Debug(">>")
	handler := pathNode.Operation.OperationType.Handler
	if handler != nil {
		return handler(d, matchingNodes, pathNode)
	}
	return nil, fmt.Errorf("Unknown operator %v", pathNode.Operation.OperationType)

}