Function _QueryGraph_ExtractNode

src/graph/query_graph.c:135–180

extracts node from 'qg' and places a copy of into 'graph'

// extracts node from 'qg' and places a copy of into 'graph'
static void _QueryGraph_ExtractNode
(
	const QueryGraph *qg,
	QueryGraph *graph,
	const cypher_astnode_t *ast_node
) {

	// validate inputs
	ASSERT(qg        !=  NULL);
	ASSERT(graph     !=  NULL);
	ASSERT(ast_node  !=  NULL);

	// see if node is already in 'graph'
	const char *alias = AST_ToString(ast_node);
	QGNode *n = QueryGraph_GetNodeByAlias(graph, alias);

	if(n == NULL) {
		// node is missing from 'graph', try getting it from 'qg'
		n = QueryGraph_GetNodeByAlias(qg, alias);
		if(n == NULL) {
			// node is missing from 'qg', create it
			// it is possible to get into a situation where we try to extract
			// a path which contains entities that are missing from the
			// "holistic" query graph consider:
			// MATCH (a) WITH a WHERE (a)-[]->(:L1) in this case due to
			// clause scoping only node 'a' is in 'qg' the filtered pattern
			// which is being extracted from 'qg' has additional entities:
			// an anonymous edge and node
			_QueryGraphAddNode(graph, ast_node);
		} else {
			// add a clone of the original node
			n = QGNode_Clone(n);

			// clear node label information
			array_clear(n->labels);
			array_clear(n->labelsID);

			QueryGraph_AddNode(graph, n);
			// set node label information
			_QueryGraphSetNodeLabel(n, ast_node);
		}
	} else {
		// set node label information
		_QueryGraphSetNodeLabel(n, ast_node);
	}
}

// extracts edge from 'qg' and places a copy of into 'graph'
static void _QueryGraph_ExtractEdge