graph

type Edge struct {
	From  NodeID            `json:"from"`
	To    NodeID            `json:"to"`
	Type  EdgeType          `json:"type"`
	Props map[string]string `json:"props,omitempty"`
}

type EdgeType string

type Node struct {
	ID    NodeID            `json:"id"`
	Kind  string            `json:"kind"`
	Name  string            `json:"name,omitempty"`
	Path  string            `json:"path,omitempty"`
	Props map[string]string `json:"props,omitempty"`
}

type NodeID string

type Store interface {
	Close() error

	PutNode(node Node) error
	GetNode(id NodeID) (Node, error)
	DeleteNode(id NodeID) error

	PutEdge(edge Edge) error
	DeleteEdge(from NodeID, to NodeID, edgeType EdgeType) error

	// OutEdges returns edges leaving from. If edgeType is non-empty, results are filtered.
	OutEdges(from NodeID, edgeType EdgeType) ([]Edge, error)

	// InEdges returns edges entering to. If edgeType is non-empty, results are filtered.
	InEdges(to NodeID, edgeType EdgeType) ([]Edge, error)

	// ForEachNode invokes fn for every node. Iteration stops early if fn returns false.
	ForEachNode(fn func(Node) bool) error

	// GetNodeByURI resolves a canonical repo:// URI via the secondary unique index.
	// Nodes without a URI are not findable this way.
	GetNodeByURI(repoURI string) (Node, error)
}