public Expression visit()

in asterix-graphix/src/main/java/org/apache/asterix/graphix/lang/rewrite/visitor/PreRewriteCheckVisitor.java [141:201]
51 lines of code
9 McCabe index (conditional complexity)

    public Expression visit(FromGraphClause fromGraphClause, ILangExpression arg) throws CompilationException {
        environmentMap.put(fromGraphClause, new PreRewriteCheckEnvironment());

        // Establish the vertex and edge labels associated with this FROM-GRAPH-CLAUSE.
        GraphConstructor graphConstructor = fromGraphClause.getGraphConstructor();
        if (graphConstructor == null) {
            DataverseName dataverseName = (fromGraphClause.getDataverseName() == null)
                    ? metadataProvider.getDefaultDataverseName() : fromGraphClause.getDataverseName();
            Identifier graphName = fromGraphClause.getGraphName();

            // First, see if we can fetch the graph constructor from our declared graphs.
            GraphIdentifier graphIdentifier = fromGraphClause.getGraphIdentifier(metadataProvider);
            DeclareGraphStatement declaredGraph = declaredGraphs.get(graphIdentifier);
            if (declaredGraph != null) {
                graphConstructor = declaredGraph.getGraphConstructor();

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

                    } else {
                        graphFromMetadata.getGraphSchema().getVertices().stream().map(Vertex::getLabel)
                                .forEach(environmentMap.get(fromGraphClause).elementLabels::add);
                        graphFromMetadata.getGraphSchema().getEdges().forEach(e -> {
                            environmentMap.get(fromGraphClause).elementLabels.add(e.getSourceLabel());
                            environmentMap.get(fromGraphClause).elementLabels.add(e.getDestinationLabel());
                            environmentMap.get(fromGraphClause).edgeLabels.add(e.getLabel());
                        });
                    }

                } catch (AlgebricksException e) {
                    throw new CompilationException(ErrorCode.COMPILATION_ERROR, fromGraphClause.getSourceLocation(),
                            "Graph " + graphName.getValue() + " does not exist.");
                }
            }
        }
        if (graphConstructor != null) {
            graphConstructor.getVertexElements().stream().map(GraphConstructor.VertexConstructor::getLabel)
                    .forEach(environmentMap.get(fromGraphClause).elementLabels::add);
            graphConstructor.getEdgeElements().forEach(e -> {
                environmentMap.get(fromGraphClause).elementLabels.add(e.getSourceLabel());
                environmentMap.get(fromGraphClause).elementLabels.add(e.getDestinationLabel());
                environmentMap.get(fromGraphClause).edgeLabels.add(e.getEdgeLabel());
            });
            graphConstructor.accept(this, fromGraphClause);
        }

        // We need to pass our FROM-GRAPH-CLAUSE to our MATCH-CLAUSE.
        for (MatchClause matchClause : fromGraphClause.getMatchClauses()) {
            matchClause.accept(this, fromGraphClause);
        }
        for (AbstractBinaryCorrelateClause correlateClause : fromGraphClause.getCorrelateClauses()) {
            correlateClause.accept(this, arg);
        }
        return null;
    }