Examples with RelTableRef org.apache.calcite.rex.RexTableInputRef.RelTableRef used on opensource projects

Example 16 with RelTableRef

use of org.apache.calcite.rex.RexTableInputRef.RelTableRef in project calcite by apache.

the class AbstractMaterializedViewRule method generateTableMappings.

/**
 * It will flatten a multimap containing table references to table references,
 * producing all possible combinations of mappings. Each of the mappings will
 * be bi-directional.
 */
private static List<BiMap<RelTableRef, RelTableRef>> generateTableMappings(Multimap<RelTableRef, RelTableRef> multiMapTables) {
    if (multiMapTables.isEmpty()) {
        return ImmutableList.of();
    }
    List<BiMap<RelTableRef, RelTableRef>> result = ImmutableList.<BiMap<RelTableRef, RelTableRef>>of(HashBiMap.<RelTableRef, RelTableRef>create());
    for (Entry<RelTableRef, Collection<RelTableRef>> e : multiMapTables.asMap().entrySet()) {
        if (e.getValue().size() == 1) {
            // Only one reference, we can just add it to every map
            RelTableRef target = e.getValue().iterator().next();
            for (BiMap<RelTableRef, RelTableRef> m : result) {
                m.put(e.getKey(), target);
            }
            continue;
        }
        // Multiple references: flatten
        ImmutableList.Builder<BiMap<RelTableRef, RelTableRef>> newResult = ImmutableList.builder();
        for (RelTableRef target : e.getValue()) {
            for (BiMap<RelTableRef, RelTableRef> m : result) {
                if (!m.containsValue(target)) {
                    final BiMap<RelTableRef, RelTableRef> newM = HashBiMap.<RelTableRef, RelTableRef>create(m);
                    newM.put(e.getKey(), target);
                    newResult.add(newM);
                }
            }
        }
        result = newResult.build();
    }
    return result;
}