Move StructuredSubgraph alongside batch merge function.

`graphstore` package owns entire batch merge operation.
Added tests for node and rel batching.

graph/graph.go

@@ -6,7 +6,6 @@ package graph
 import (
 	"fmt"
 	"sort"
-	"strings"
 )
 
 // ========================================
@@ -160,167 +159,3 @@ func (r *Relationship) Serialize() *SerializedRel {
 	srel["end"] = r.End.Props
 	return &srel
 }
-
-// ========================================
-// Structured Subgraph
-// ========================================
-
-// StructuredSubgraph is a structured collection of nodes and relationships for
-// the purpose of conducting batch operations.
-type StructuredSubgraph struct {
-	// A map of grouped nodes, batched by their label combinations.
-	nodes map[string][]*Node
-	// A map of grouped relationships, batched by their type and related node
-	// labels.
-	rels map[string][]*Relationship
-	// Provides node property keys used to match nodes with given labels in the
-	// database.
-	matchProvider MatchKeysProvider
-}
-
-// NewStructuredSubgraph creates an empty structured subgraph with the given
-// match keys provider.
-func NewStructuredSubgraph(matchProvider MatchKeysProvider) *StructuredSubgraph {
-	return &StructuredSubgraph{
-		nodes:         make(map[string][]*Node),
-		rels:          make(map[string][]*Relationship),
-		matchProvider: matchProvider,
-	}
-}
-
-// AddNode adds a node into the subgraph.
-func (s *StructuredSubgraph) AddNode(node *Node) error {
-
-	// Verify that the node has defined match property values.
-	matchLabel, _, err := node.MatchProps(s.matchProvider)
-	if err != nil {
-		return fmt.Errorf("invalid node: %s", err)
-	}
-
-	// Determine the node's batch key.
-	batchKey := createNodeBatchKey(matchLabel, node.Labels.ToArray())
-
-	if _, exists := s.nodes[batchKey]; !exists {
-		s.nodes[batchKey] = []*Node{}
-	}
-
-	// Add the node to the subgraph.
-	s.nodes[batchKey] = append(s.nodes[batchKey], node)
-
-	return nil
-}
-
-// AddRel adds a relationship into the subgraph.
-func (s *StructuredSubgraph) AddRel(rel *Relationship) error {
-
-	// Verify that the start node has defined match property values.
-	startLabel, _, err := rel.Start.MatchProps(s.matchProvider)
-	if err != nil {
-		return fmt.Errorf("invalid start node: %s", err)
-	}
-
-	// Verify that the end node has defined match property values.
-	endLabel, _, err := rel.End.MatchProps(s.matchProvider)
-	if err != nil {
-		return fmt.Errorf("invalid end node: %s", err)
-	}
-
-	// Determine the relationship's batch key.
-	batchKey := createRelBatchKey(rel.Type, startLabel, endLabel)
-
-	if _, exists := s.rels[batchKey]; !exists {
-		s.rels[batchKey] = []*Relationship{}
-	}
-
-	// Add the relationship to the subgraph.
-	s.rels[batchKey] = append(s.rels[batchKey], rel)
-
-	return nil
-}
-
-// GetNodes returns the nodes grouped under the given batch key.
-func (s *StructuredSubgraph) GetNodes(nodeKey string) []*Node {
-	return s.nodes[nodeKey]
-}
-
-// GetRels returns the rels grouped under the given batch key.
-func (s *StructuredSubgraph) GetRels(relKey string) []*Relationship {
-	return s.rels[relKey]
-}
-
-func (s *StructuredSubgraph) MatchProvider() MatchKeysProvider {
-	return s.matchProvider
-}
-
-// NodeCount returns the number of nodes in the subgraph.
-func (s *StructuredSubgraph) NodeCount() int {
-	count := 0
-	for l := range s.nodes {
-		count += len(s.nodes[l])
-	}
-	return count
-}
-
-// RelCount returns the number of relationships in the subgraph.
-func (s *StructuredSubgraph) RelCount() int {
-	count := 0
-	for t := range s.rels {
-		count += len(s.rels[t])
-	}
-	return count
-}
-
-// NodeKeys returns the list of node batch keys in the subgraph.
-func (s *StructuredSubgraph) NodeKeys() []string {
-	keys := []string{}
-	for l := range s.nodes {
-		keys = append(keys, l)
-	}
-	return keys
-}
-
-// RelKeys returns the list of relationship batch keys in the subgraph.
-func (s *StructuredSubgraph) RelKeys() []string {
-	keys := []string{}
-	for t := range s.rels {
-		keys = append(keys, t)
-	}
-	return keys
-}
-
-// createNodeBatchKey returns the serialized node labels for batching.
-func createNodeBatchKey(matchLabel string, labels []string) string {
-	sort.Strings(labels)
-	serializedLabels := strings.Join(labels, ",")
-	return fmt.Sprintf("%s:%s", matchLabel, serializedLabels)
-}
-
-// createRelBatchKey returns the serialized relationship type and start/end node
-// labels for batching.
-func createRelBatchKey(
-	rtype string, startLabel string, endLabel string) string {
-	return strings.Join([]string{rtype, startLabel, endLabel}, ",")
-}
-
-// DeserializeNodeBatchKey returns the list of node labels from the serialized batch
-// key.
-func DeserializeNodeBatchKey(batchKey string) (string, []string, error) {
-	parts := strings.Split(batchKey, ":")
-	if len(parts) != 2 {
-		return "", nil, fmt.Errorf("invalid node batch key: %s", batchKey)
-	}
-	matchLabel, serializedLabels := parts[0], parts[1]
-	labels := strings.Split(serializedLabels, ",")
-	return matchLabel, labels, nil
-}
-
-// DeserializeRelBatchKey returns the relationship type, start node label, and end
-// node label from the serialized batch key. Panics if the batch key is invalid.
-func DeserializeRelBatchKey(batchKey string) (string, string, string, error) {
-	parts := strings.Split(batchKey, ",")
-	if len(parts) != 3 {
-		return "", "", "", fmt.Errorf("invalid relationship batch key: %s", batchKey)
-	}
-	rtype, startLabel, endLabel := parts[0], parts[1], parts[2]
-	return rtype, startLabel, endLabel, nil
-}