Add filter, add READMES

backend_go/graph_export.go

@@ -0,0 +1,98 @@
+package main
+
+type termKey struct {
+	termType string
+	key      string
+}
+
+type termMeta struct {
+	termType string
+	iri      string
+}
+
+func graphFromSparqlBindings(
+	bindings []map[string]sparqlTerm,
+	nodeLimit int,
+	includeBNodes bool,
+) (nodes []Node, edges []Edge) {
+	nodeIDByKey := map[termKey]int{}
+	nodeMeta := make([]termMeta, 0, min(nodeLimit, 4096))
+
+	getOrAdd := func(term sparqlTerm) (int, bool) {
+		if term.Type == "" || term.Value == "" {
+			return 0, false
+		}
+		if term.Type == "literal" {
+			return 0, false
+		}
+
+		var key termKey
+		var meta termMeta
+
+		if term.Type == "bnode" {
+			if !includeBNodes {
+				return 0, false
+			}
+			key = termKey{termType: "bnode", key: term.Value}
+			meta = termMeta{termType: "bnode", iri: "_:" + term.Value}
+		} else {
+			key = termKey{termType: "uri", key: term.Value}
+			meta = termMeta{termType: "uri", iri: term.Value}
+		}
+
+		if existing, ok := nodeIDByKey[key]; ok {
+			return existing, true
+		}
+		if len(nodeMeta) >= nodeLimit {
+			return 0, false
+		}
+		nid := len(nodeMeta)
+		nodeIDByKey[key] = nid
+		nodeMeta = append(nodeMeta, meta)
+		return nid, true
+	}
+
+	for _, b := range bindings {
+		sTerm := b["s"]
+		oTerm := b["o"]
+		pTerm := b["p"]
+
+		sid, okS := getOrAdd(sTerm)
+		oid, okO := getOrAdd(oTerm)
+		if !okS || !okO {
+			continue
+		}
+
+		pred := pTerm.Value
+		if pred == "" {
+			continue
+		}
+
+		edges = append(edges, Edge{
+			Source:    sid,
+			Target:    oid,
+			Predicate: pred,
+		})
+	}
+
+	nodes = make([]Node, len(nodeMeta))
+	for i, m := range nodeMeta {
+		nodes[i] = Node{
+			ID:       i,
+			TermType: m.termType,
+			IRI:      m.iri,
+			Label:    nil,
+			X:        0,
+			Y:        0,
+		}
+	}
+
+	return nodes, edges
+}
+
+func min(a, b int) int {
+	if a < b {
+		return a
+	}
+	return b
+}