public Expression visit()

in asterix-graphix/src/main/java/org/apache/asterix/graphix/lang/rewrite/visitor/ElementLookupTableVisitor.java [83:152]
63 lines of code
16 McCabe index (conditional complexity)

    public Expression visit(FromGraphClause fromGraphClause, ILangExpression arg) throws CompilationException {
        for (MatchClause m : fromGraphClause.getMatchClauses()) {
            m.accept(this, null);
        }

        GraphConstructor graphConstructor = fromGraphClause.getGraphConstructor();
        GraphIdentifier graphIdentifier = fromGraphClause.getGraphIdentifier(metadataProvider);
        if (graphConstructor == null) {
            DataverseName dataverseName = (fromGraphClause.getDataverseName() == null)
                    ? metadataProvider.getDefaultDataverseName() : fromGraphClause.getDataverseName();
            Identifier graphName = fromGraphClause.getGraphName();

            // Our query refers to a named graph. First see if we can find this in our declared graph set.
            DeclareGraphStatement declaredGraph = declaredGraphs.get(graphIdentifier);
            if (declaredGraph != null) {
                graphConstructor = declaredGraph.getGraphConstructor();

            } else {
                // Otherwise, load this from our metadata.
                Graph graphFromMetadata;
                try {
                    graphFromMetadata = GraphixMetadataExtension.getGraph(metadataProvider.getMetadataTxnContext(),
                            dataverseName, graphName.getValue());
                    if (graphFromMetadata == null) {
                        throw new CompilationException(ErrorCode.COMPILATION_ERROR, fromGraphClause.getSourceLocation(),
                                "Graph " + graphName.getValue() + " does not exist.");
                    }

                } catch (AlgebricksException e) {
                    throw new CompilationException(ErrorCode.COMPILATION_ERROR, fromGraphClause.getSourceLocation(),
                            "Graph " + graphName.getValue() + " does not exist.");
                }

                for (Vertex vertex : graphFromMetadata.getGraphSchema().getVertices()) {
                    if (referencedElementLabels.contains(vertex.getLabel())) {
                        GraphElementDeclaration vertexDecl = parse(vertex, parserFactory, warningCollector);
                        elementLookupTable.put(vertex.getIdentifier(), vertexDecl);
                        elementLookupTable.putVertexKey(vertex.getIdentifier(), vertex.getPrimaryKeyFieldNames());
                    }
                }
                for (Edge edge : graphFromMetadata.getGraphSchema().getEdges()) {
                    if (referencedEdgeLabels.contains(edge.getLabel())) {
                        GraphElementDeclaration edgeDecl = parse(edge, parserFactory, warningCollector);
                        elementLookupTable.put(edge.getIdentifier(), edgeDecl);
                        elementLookupTable.putEdgeKeys(edge.getIdentifier(), edge.getSourceKeyFieldNames(),
                                edge.getDestinationKeyFieldNames());
                    }
                }
            }
        }
        if (graphConstructor != null) {
            for (GraphConstructor.VertexConstructor vertex : graphConstructor.getVertexElements()) {
                if (referencedElementLabels.contains(vertex.getLabel())) {
                    VertexIdentifier identifier = new VertexIdentifier(graphIdentifier, vertex.getLabel());
                    elementLookupTable.put(identifier, new GraphElementDeclaration(identifier, vertex.getExpression()));
                    elementLookupTable.putVertexKey(identifier, vertex.getPrimaryKeyFields());
                }
            }
            for (GraphConstructor.EdgeConstructor edge : graphConstructor.getEdgeElements()) {
                if (referencedEdgeLabels.contains(edge.getEdgeLabel())) {
                    EdgeIdentifier identifier = new EdgeIdentifier(graphIdentifier, edge.getSourceLabel(),
                            edge.getEdgeLabel(), edge.getDestinationLabel());
                    elementLookupTable.put(identifier, new GraphElementDeclaration(identifier, edge.getExpression()));
                    elementLookupTable.putEdgeKeys(identifier, edge.getSourceKeyFields(),
                            edge.getDestinationKeyFields());
                }
            }
        }
        return null;
    }