public void accept()

in asterix-graphix/src/main/java/org/apache/asterix/graphix/lang/rewrite/canonical/CanonicalElementExpansionConsumer.java [230:303]
62 lines of code
11 McCabe index (conditional complexity)

        public void accept(AbstractExpression canonicalExpr, PathPatternExpr pathPatternExpr)
                throws CompilationException {
            EdgePatternExpr ambiguousEdgePattern = (EdgePatternExpr) ambiguousElement;
            VertexPatternExpr ambiguousLeftVertex = ambiguousEdgePattern.getLeftVertex();
            VertexPatternExpr ambiguousRightVertex = ambiguousEdgePattern.getRightVertex();
            EdgeDescriptor ambiguousEdgeDescriptor = ambiguousEdgePattern.getEdgeDescriptor();
            VariableExpr edgeVariable = ambiguousEdgeDescriptor.getVariableExpr();
            PathPatternExpr canonicalPathPatternExpr = (PathPatternExpr) canonicalExpr;
            List<EdgePatternExpr> canonicalEdges = canonicalPathPatternExpr.getEdgeExpressions();
            VertexPatternExpr canonicalLeftVertex = canonicalEdges.get(0).getLeftVertex();
            VertexPatternExpr canonicalRightVertex = canonicalEdges.get(canonicalEdges.size() - 1).getRightVertex();

            // Iterate through our edge list.
            List<EdgePatternExpr> edgeExpressions = pathPatternExpr.getEdgeExpressions();
            ListIterator<EdgePatternExpr> edgeIterator = edgeExpressions.listIterator();
            while (edgeIterator.hasNext()) {
                EdgePatternExpr workingEdge = edgeIterator.next();
                if (workingEdge.equals(ambiguousEdgePattern)) {
                    edgeIterator.remove();

                    // We need to generate new variables for each edge in our new path.
                    List<EdgePatternExpr> canonicalEdgeListCopy = new ArrayList<>();
                    for (EdgePatternExpr canonicalEdge : canonicalEdges) {
                        EdgePatternExpr canonicalEdgeCopy = deepCopyVisitor.visit(canonicalEdge, null);
                        EdgeDescriptor canonicalEdgeCopyDescriptor = canonicalEdgeCopy.getEdgeDescriptor();
                        VariableExpr edgeVariableCopy = graphixRewritingContext.getGraphixVariableCopy(edgeVariable);
                        canonicalEdgeCopyDescriptor.setVariableExpr(edgeVariableCopy);
                        canonicalEdgeListCopy.add(canonicalEdgeCopy);
                        edgeIterator.add(canonicalEdgeCopy);
                    }

                    // Determine our new vertex list (we want to keep the order of our current vertex list).
                    List<VertexPatternExpr> canonicalVertexListCopy = new ArrayList<>();
                    ListIterator<VertexPatternExpr> pathPatternVertexIterator =
                            pathPatternExpr.getVertexExpressions().listIterator();
                    while (pathPatternVertexIterator.hasNext()) {
                        VertexPatternExpr currentPathPatternVertex = pathPatternVertexIterator.next();
                        VariableExpr currentVariable = currentPathPatternVertex.getVariableExpr();
                        VariableExpr ambiguousLeftVar = ambiguousLeftVertex.getVariableExpr();
                        VariableExpr ambiguousRightVar = ambiguousRightVertex.getVariableExpr();
                        if (currentVariable.equals(ambiguousLeftVar)) {
                            // Add canonical path vertices.
                            List<VertexPatternExpr> canonicalVertices = canonicalPathPatternExpr.getVertexExpressions();
                            for (VertexPatternExpr vertexExpr : canonicalVertices) {
                                canonicalVertexListCopy.add(deepCopyVisitor.visit(vertexExpr, null));
                                VariableExpr vertexVar = vertexExpr.getVariableExpr();
                                if (!vertexVar.equals(ambiguousLeftVar) && !vertexVar.equals(ambiguousRightVar)) {
                                    pathPatternVertexIterator.add(vertexExpr);
                                }
                            }
                        }
                    }

                    // Build a new path record.
                    RecordConstructor pathRecord = new RecordConstructor();
                    pathRecord.setSourceLocation(workingEdge.getSourceLocation());
                    buildPathRecord(canonicalVertexListCopy, canonicalEdgeListCopy, pathRecord);
                    LetClause pathBinding = new LetClause(deepCopyVisitor.visit(edgeVariable, null), pathRecord);
                    pathPatternExpr.getReboundSubPathList().add(pathBinding);

                } else {
                    if (workingEdge.getLeftVertex().equals(ambiguousLeftVertex)) {
                        workingEdge.setLeftVertex(deepCopyVisitor.visit(canonicalLeftVertex, null));
                    }
                    if (workingEdge.getRightVertex().equals(ambiguousRightVertex)) {
                        workingEdge.setRightVertex(deepCopyVisitor.visit(canonicalRightVertex, null));
                    }
                }
            }

            // Iterate through our vertex list.
            replaceEdgeVerticesAndJoinCopiesInIterator(pathPatternExpr, ambiguousLeftVertex, ambiguousRightVertex,
                    canonicalLeftVertex, canonicalRightVertex);
        }