public Expression visit()

in asterix-graphix/src/main/java/org/apache/asterix/graphix/lang/rewrite/visitor/GraphixLoweringVisitor.java [128:193]
55 lines of code
13 McCabe index (conditional complexity)

    public Expression visit(SelectBlock selectBlock, ILangExpression arg) throws CompilationException {
        SelectExpression selectExpression = (SelectExpression) arg;
        if (selectBlock.hasFromClause() && selectBlock.getFromClause() instanceof FromGraphClause) {
            FromGraphClause fromGraphClause = (FromGraphClause) selectBlock.getFromClause();
            MetadataProvider metadataProvider = graphixRewritingContext.getMetadataProvider();
            GraphIdentifier graphIdentifier = fromGraphClause.getGraphIdentifier(metadataProvider);
            SourceLocation sourceLocation = fromGraphClause.getSourceLocation();

            // Initialize a new lowering environment.
            LoweringEnvironment newEnvironment =
                    new LoweringEnvironment(graphixRewritingContext, graphIdentifier, sourceLocation);
            actionFactory.reset(graphIdentifier);

            // We will remove the FROM-GRAPH node and replace this with a FROM node on the child visit.
            environmentStack.addLast(newEnvironment);
            super.visit(selectBlock, arg);
            environmentStack.removeLast();

            // See if we need to perform a pass for schema enrichment. By default, we decorate "as-needed".
            String schemaDecorateVertexKey = SchemaDecorateVertexOption.OPTION_KEY_NAME;
            String schemaDecorateEdgeKey = SchemaDecorateEdgeOption.OPTION_KEY_NAME;
            IGraphixCompilerOption vertexModeOption = graphixRewritingContext.getSetting(schemaDecorateVertexKey);
            IGraphixCompilerOption edgeModeOption = graphixRewritingContext.getSetting(schemaDecorateEdgeKey);
            SchemaDecorateVertexOption vertexMode = (SchemaDecorateVertexOption) vertexModeOption;
            SchemaDecorateEdgeOption edgeMode = (SchemaDecorateEdgeOption) edgeModeOption;

            // See if there are any Graphix functions used in our query.
            Set<FunctionIdentifier> graphixFunctionSet = new LinkedHashSet<>();
            topLevelSelectExpression.accept(new AbstractGraphixQueryVisitor() {
                @Override
                public Expression visit(CallExpr callExpr, ILangExpression arg) throws CompilationException {
                    FunctionSignature functionSignature = callExpr.getFunctionSignature();
                    if (functionSignature.getDataverseName().equals(GraphixFunctionIdentifiers.GRAPHIX_DV)) {
                        FunctionIdentifier functionID = functionSignature.createFunctionIdentifier();
                        if ((vertexMode == SchemaDecorateVertexOption.NEVER && isVertexFunction(functionID))
                                || (edgeMode == SchemaDecorateEdgeOption.NEVER && isEdgeFunction(functionID))) {
                            throw new CompilationException(ErrorCode.COMPILATION_ERROR, callExpr.getSourceLocation(),
                                    "Schema-decorate mode has been set to 'NEVER', but schema-decoration is required "
                                            + "to realize the function" + functionSignature + "!");
                        }
                        graphixFunctionSet.add(functionID);
                    }
                    return super.visit(callExpr, arg);
                }
            }, null);

            // Perform a pass for schema enrichment, if needed.
            boolean isVertexModeAlways = vertexMode == SchemaDecorateVertexOption.ALWAYS;
            boolean isEdgeModeAlways = edgeMode == SchemaDecorateEdgeOption.ALWAYS;
            if (!graphixFunctionSet.isEmpty() || isVertexModeAlways || isEdgeModeAlways) {
                SchemaEnrichmentVisitor schemaEnrichmentVisitor = new SchemaEnrichmentVisitor(vertexMode, edgeMode,
                        elementLookupTable, branchLookupTable, graphIdentifier, selectBlock, graphixFunctionSet);
                selectExpression.accept(schemaEnrichmentVisitor, null);
                if (selectExpression.hasOrderby()) {
                    selectExpression.getOrderbyClause().accept(schemaEnrichmentVisitor, null);
                }
                if (selectExpression.hasLimit()) {
                    selectExpression.getLimitClause().accept(schemaEnrichmentVisitor, null);
                }
            }

        } else {
            super.visit(selectBlock, arg);
        }
        return null;
    }