@Override
  public FileFormatProxy getFileFormatProxy(FileMetadataExprType type) {
    switch (type) {
    case ORC_SARG: return new OrcFileFormatProxy();
    default: throw new RuntimeException("Unsupported format " + type);
    }
  }
The basic implementation of PartitionExpressionProxy that uses ql package classes.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/ppr/PartitionExpressionForMetastore.java