private static Set matchJointIndexes()

in hugegraph-core/src/main/java/org/apache/hugegraph/backend/tx/GraphIndexTransaction.java [960:1015]
43 lines of code
12 McCabe index (conditional complexity)

    private static Set<IndexLabel> matchJointIndexes(
                                   ConditionQuery query,
                                   Set<IndexLabel> indexLabels) {
        if (query.hasNeqCondition()) {
            return ImmutableSet.of();
        }
        Set<Id> queryPropKeys = query.userpropKeys();
        assert !queryPropKeys.isEmpty();
        Set<IndexLabel> allILs = InsertionOrderUtil.newSet(indexLabels);

        // Handle range/search index first
        Set<IndexLabel> matchedIndexLabels = InsertionOrderUtil.newSet();
        if (query.hasRangeCondition() || query.hasSearchCondition()) {
            matchedIndexLabels = matchRangeOrSearchIndexLabels(query, allILs);
            if (matchedIndexLabels.isEmpty()) {
                return ImmutableSet.of();
            }
            allILs.removeAll(matchedIndexLabels);

            // Remove matched queryPropKeys
            for (IndexLabel il : matchedIndexLabels) {
                // Only one field each range/search index-label
                queryPropKeys.remove(il.indexField());
            }
            // Return if all fields are matched
            if (queryPropKeys.isEmpty()) {
                return matchedIndexLabels;
            }
        }

        // Handle secondary indexes
        Set<Id> indexFields = InsertionOrderUtil.newSet();
        for (IndexLabel indexLabel : allILs) {
            // Range index equal-condition and secondary index can joint
            if (indexLabel.indexType().isSearch()) {
                // Search index must be handled at the previous step
                continue;
            }

            List<Id> fields = indexLabel.indexFields();
            // Collect all fields prefix
            for (Id field : fields) {
                if (!queryPropKeys.contains(field)) {
                    break;
                }
                matchedIndexLabels.add(indexLabel);
                indexFields.add(field);
            }
        }
        // Must match all fields
        if (indexFields.equals(queryPropKeys)) {
            return matchedIndexLabels;
        } else {
            return ImmutableSet.of();
        }
    }