@Override
  public FileMetadataExprType getMetadataType(String inputFormat) {
    try {
      Class<?> ifClass = Class.forName(inputFormat);
      if (OrcInputFormat.class.isAssignableFrom(ifClass)) {
        return FileMetadataExprType.ORC_SARG;
      }
      return null;
    } catch (Throwable t) {
      LOG.warn("Can't create the class for input format " + inputFormat, t);
      return null;
    }
  }
The basic implementation of PartitionExpressionProxy that uses ql package classes.
ql/src/java/org/apache/hadoop/hive/ql/optimizer/ppr/PartitionExpressionForMetastore.java