ceph/src/arrow/c_glib/example/lua/read-stream.lua

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   5 -- to you under the Apache License, Version 2.0 (the
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   7 -- with the License.  You may obtain a copy of the License at
   8 --
   9 --   http://www.apache.org/licenses/LICENSE-2.0
  10 --
  11 -- Unless required by applicable law or agreed to in writing,
  12 -- software distributed under the License is distributed on an
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  14 -- KIND, either express or implied.  See the License for the
  15 -- specific language governing permissions and limitations
  16 -- under the License.
  17
  18 local lgi = require 'lgi'
  19 local Arrow = lgi.Arrow
  20
  21 local input_path = arg[1] or "/tmp/stream.arrow";
  22
  23 local input = Arrow.MemoryMappedInputStream.new(input_path)
  24 local reader = Arrow.RecordBatchStreamReader.new(input)
  25
  26 local i = 0
  27 while true do
  28    local record_batch = reader:read_next()
  29    if not record_batch then
  30       break
  31    end
  32
  33    print(string.rep("=", 40))
  34    print("record-batch["..i.."]:")
  35    for j = 0, record_batch:get_n_columns() - 1 do
  36       local column_name = record_batch:get_column_name(j)
  37       local column_data = record_batch:get_column_data(j)
  38       io.write("  "..column_name..": [")
  39       for k = 0, record_batch:get_n_rows() - 1 do
  40          if k > 0 then
  41             io.write(", ")
  42          end
  43          io.write(column_data:get_value(k))
  44       end
  45       print("]")
  46    end
  47
  48    i = i + 1
  49 end
  50
  51 input:close()