Wrote write goroutine functions.

Refactored subpackages back to root package.

graph.go

@@ -0,0 +1,158 @@
+package heartwood
+
+import (
+	"fmt"
+	"sort"
+)
+
+// ========================================
+// Types
+// ========================================
+
+// Properties represents a map of node or relationship props.
+type Properties map[string]any
+
+// ========================================
+// Match Key Provider
+// ========================================
+
+// MatchKeysProvider defines methods for querying a mapping of node labels and
+// the property keys used to match nodes with them.
+type MatchKeysProvider interface {
+	// GetLabels returns the array of node labels in the mapping.
+	GetLabels() []string
+
+	// GetKeys returns the node property keys used to match nodes with the
+	// given label and a boolean indicating the success of the lookup.
+	GetKeys(label string) ([]string, bool)
+}
+
+// SimpleMatchKeys is a simple implementation of the MatchKeysProvider interface.
+type SimpleMatchKeys struct {
+	Keys map[string][]string
+}
+
+func (p *SimpleMatchKeys) GetLabels() []string {
+	labels := []string{}
+	for l := range p.Keys {
+		labels = append(labels, l)
+	}
+	return labels
+}
+
+func (p *SimpleMatchKeys) GetKeys(label string) ([]string, bool) {
+	if keys, exists := p.Keys[label]; exists {
+		return keys, exists
+	} else {
+		return nil, exists
+	}
+}
+
+// ========================================
+// Nodes
+// ========================================
+
+// Node represents a Neo4j node entity, encapsulating its labels and
+// properties.
+type Node struct {
+	// Set of labels on the node.
+	Labels Set[string]
+	// Mapping of properties on the node.
+	Props Properties
+}
+
+// NewNode creates a new node with the given label and properties.
+func NewNode(label string, props Properties) *Node {
+	if props == nil {
+		props = make(Properties)
+	}
+	return &Node{
+		Labels: NewSet(label),
+		Props:  props,
+	}
+}
+
+// MatchProps returns the node label and the property values to match it in the
+// database.
+func (n *Node) MatchProps(
+	matchProvider MatchKeysProvider) (string, Properties, error) {
+
+	// Iterate over each label on the node, checking whether each has match
+	// keys associated with it.
+	labels := n.Labels.ToArray()
+	sort.Strings(labels)
+	for _, label := range labels {
+		if keys, exists := matchProvider.GetKeys(label); exists {
+			props := make(Properties)
+
+			// Get the property values associated with each match key.
+			for _, key := range keys {
+				if value, exists := n.Props[key]; exists {
+					props[key] = value
+				} else {
+
+					// If any match property values are missing, return an
+					// error.
+					return label, nil,
+						fmt.Errorf(
+							"missing property %s for label %s", key, label)
+				}
+			}
+
+			// Return the label and match properties
+			return label, props, nil
+		}
+	}
+
+	// If none of the node labels have defined match keys, return an error.
+	return "", nil, fmt.Errorf("no recognized label found in %v", n.Labels)
+}
+
+type SerializedNode = Properties
+
+func (n *Node) Serialize() *SerializedNode {
+	return &n.Props
+}
+
+// ========================================
+// Relationships
+// ========================================
+
+// Relationship represents a Neo4j relationship between two nodes, including
+// its type and properties.
+type Relationship struct {
+	// The relationship type.
+	Type string
+	// The start node for the relationship.
+	Start *Node
+	// The end node for the relationship.
+	End *Node
+	// Mapping of properties on the relationship
+	Props Properties
+}
+
+// NewRelationship creates a new relationship with the given type, start node,
+// end node, and properties
+func NewRelationship(
+	rtype string, start *Node, end *Node, props Properties) *Relationship {
+
+	if props == nil {
+		props = make(Properties)
+	}
+	return &Relationship{
+		Type:  rtype,
+		Start: start,
+		End:   end,
+		Props: props,
+	}
+}
+
+type SerializedRel = map[string]Properties
+
+func (r *Relationship) Serialize() *SerializedRel {
+	srel := make(map[string]Properties)
+	srel["props"] = r.Props
+	srel["start"] = r.Start.Props
+	srel["end"] = r.End.Props
+	return &srel
+}