private void unifyVertexLabels()

in asterix-graphix/src/main/java/org/apache/asterix/graphix/lang/rewrite/resolve/ExhaustiveSearchResolver.java [329:404]
66 lines of code
11 McCabe index (conditional complexity)

    private void unifyVertexLabels(PatternGroup patternGroup) {
        // Pass #1: Collect all vertex variables and their labels.
        Map<VariableExpr, Set<ElementLabel>> vertexVariableMap = new HashMap<>();
        for (AbstractExpression abstractExpression : patternGroup) {
            if (abstractExpression instanceof VertexPatternExpr) {
                VertexPatternExpr vertexPatternExpr = (VertexPatternExpr) abstractExpression;
                VariableExpr vertexVariable = vertexPatternExpr.getVariableExpr();
                vertexVariableMap.putIfAbsent(vertexVariable, new HashSet<>());
                vertexVariableMap.get(vertexVariable).addAll(vertexPatternExpr.getLabels());
                SubqueryVertexJoinAnnotation hint = vertexPatternExpr.findHint(SubqueryVertexJoinAnnotation.class);
                if (hint != null) {
                    VariableExpr sourceVertexVariable = hint.getSourceVertexVariable();
                    vertexVariableMap.putIfAbsent(sourceVertexVariable, new HashSet<>());
                    vertexVariableMap.get(sourceVertexVariable).addAll(vertexPatternExpr.getLabels());
                }

            } else { // abstractExpression instanceof EdgePatternExpr
                EdgePatternExpr edgePatternExpr = (EdgePatternExpr) abstractExpression;
                VertexPatternExpr leftVertexExpr = edgePatternExpr.getLeftVertex();
                VertexPatternExpr rightVertexExpr = edgePatternExpr.getRightVertex();
                VariableExpr leftVariable = leftVertexExpr.getVariableExpr();
                VariableExpr rightVariable = rightVertexExpr.getVariableExpr();

                // Visit the vertices of our edges and their labels as well.
                vertexVariableMap.putIfAbsent(leftVariable, new HashSet<>());
                vertexVariableMap.putIfAbsent(rightVariable, new HashSet<>());
                vertexVariableMap.get(leftVariable).addAll(leftVertexExpr.getLabels());
                vertexVariableMap.get(rightVariable).addAll(rightVertexExpr.getLabels());
                SubqueryVertexJoinAnnotation leftHint = leftVertexExpr.findHint(SubqueryVertexJoinAnnotation.class);
                SubqueryVertexJoinAnnotation rightHint = rightVertexExpr.findHint(SubqueryVertexJoinAnnotation.class);
                if (leftHint != null) {
                    VariableExpr sourceVertexVariable = leftHint.getSourceVertexVariable();
                    vertexVariableMap.putIfAbsent(sourceVertexVariable, new HashSet<>());
                    vertexVariableMap.get(sourceVertexVariable).addAll(leftVertexExpr.getLabels());
                }
                if (rightHint != null) {
                    VariableExpr sourceVertexVariable = rightHint.getSourceVertexVariable();
                    vertexVariableMap.putIfAbsent(sourceVertexVariable, new HashSet<>());
                    vertexVariableMap.get(sourceVertexVariable).addAll(rightVertexExpr.getLabels());
                }
            }
        }

        // Pass #2: Copy the vertex label sets to all vertices of the same variable.
        for (AbstractExpression abstractExpression : patternGroup) {
            if (abstractExpression instanceof VertexPatternExpr) {
                VertexPatternExpr vertexPatternExpr = (VertexPatternExpr) abstractExpression;
                VariableExpr vertexVariable = vertexPatternExpr.getVariableExpr();
                vertexPatternExpr.getLabels().addAll(vertexVariableMap.get(vertexVariable));
                SubqueryVertexJoinAnnotation hint = vertexPatternExpr.findHint(SubqueryVertexJoinAnnotation.class);
                if (hint != null) {
                    vertexPatternExpr.getLabels().addAll(vertexVariableMap.get(hint.getSourceVertexVariable()));
                }

            } else { // abstractExpression instanceof EdgePatternExpr
                EdgePatternExpr edgePatternExpr = (EdgePatternExpr) abstractExpression;
                VertexPatternExpr leftVertexExpr = edgePatternExpr.getLeftVertex();
                VertexPatternExpr rightVertexExpr = edgePatternExpr.getRightVertex();

                // Visit the vertices of our edge as well.
                VariableExpr leftVariable = leftVertexExpr.getVariableExpr();
                VariableExpr rightVariable = rightVertexExpr.getVariableExpr();
                leftVertexExpr.getLabels().addAll(vertexVariableMap.get(leftVariable));
                rightVertexExpr.getLabels().addAll(vertexVariableMap.get(rightVariable));
                SubqueryVertexJoinAnnotation leftHint = leftVertexExpr.findHint(SubqueryVertexJoinAnnotation.class);
                SubqueryVertexJoinAnnotation rightHint = rightVertexExpr.findHint(SubqueryVertexJoinAnnotation.class);
                if (leftHint != null) {
                    leftVertexExpr.getLabels().addAll(vertexVariableMap.get(leftHint.getSourceVertexVariable()));
                }
                if (rightHint != null) {
                    rightVertexExpr.getLabels().addAll(vertexVariableMap.get(rightHint.getSourceVertexVariable()));
                }
            }
        }

    }