code: private List<IndexExpression> filterToIndexExpressions(Expression expression) throws IOException
      {
          List<IndexExpression> indexExpressions = new ArrayList<IndexExpression>();
          Expression.BinaryExpression be = (Expression.BinaryExpression)expression;
          ByteBuffer name = ByteBuffer.wrap(be.getLhs().toString().getBytes());
          ByteBuffer value = ByteBuffer.wrap(be.getRhs().toString().getBytes());
          switch (expression.getOpType())
          {
              case OP_EQ:
                  indexExpressions.add(new IndexExpression(name, IndexOperator.EQ, value));
                  break;
              case OP_GE:
                  indexExpressions.add(new IndexExpression(name, IndexOperator.GTE, value));
                  break;
              case OP_GT:
                  indexExpressions.add(new IndexExpression(name, IndexOperator.GT, value));
                  break;
              case OP_LE:
                  indexExpressions.add(new IndexExpression(name, IndexOperator.LTE, value));
                  break;
              case OP_LT:
                  indexExpressions.add(new IndexExpression(name, IndexOperator.LT, value));
                  break;
              case OP_AND:
                  indexExpressions.addAll(filterToIndexExpressions(be.getLhs()));
                  indexExpressions.addAll(filterToIndexExpressions(be.getRhs()));
                  break;
              default:
                  throw new IOException("Unsupported expression type: " + expression.getOpType().name());
          }
          return indexExpressions;
      }
docs: get a list of Cassandra IndexExpression from Pig expression