Dear Monks,

I seek wisdom for implementing a parser in Perl. I am more an “end user” when it comes to parsers I have limited experience in writing them.

I am thinking about implementing a Parser for ODL (Object Description Language, no not the Object Definition Language). ODL is endorsed by the PDS (Planetary Data System) and is used to describe/define data products, e.g. scientific measurements done by instruments. See below for an example then it becomes clear what I would like to parse. This offers a pretty good and short explanation.

There is some SW around…

But I am really looking for a Perl solution (yes I am biased).

A parser that can read the ODL format and generates events like “start_of_object X”, “keyword_Y” , “end_of_object Z” triggering callback functions. A bit like SAX but then for XMODL I suppose. Then I can build other stuff on top of that like validation of the data or generate other data products from it.

I have looked around on CPAN and the web and performed a Super Search…



Can anyone point me in the right direction, i.e. how to implement an (ODL) parser? Or is there already something around?

Example data file EXAMPLE.LBL

__DATA__

/***  FILE CHARACTERISTIC DATA ELEMENTS   ***/
FILE_NAME                     = "2007_11_11T10_11_47_1.DAT"
FILE_RECORDS                  = 9392
RECORD_TYPE                   = FIXED_LENGTH
RECORD_BYTES                  = 4264
RELEASE_ID                    = 0001
REVISION_ID                   = 0001

/* Table object describing the data */
OBJECT                        = TABLE
  COLUMNS                       = 42
  INTERCHANGE_FORMAT            = BINARY
  ROW_BYTES                     = 4264
  ROWS                          = 9387
  DESCRIPTION                   = "BLABLA”

  OBJECT                        = COLUMN
    COLUMN_NUMBER                 = 1
    NAME                          = SPECTRUM
    BYTES                         = 2048
    START_BYTE                    = 1
    DATA_TYPE                     = MSB_INTEGER
    DESCRIPTION                   = "
      THIS COLUMN CONTAINS THE RAW DATA OF THE 512
      CHANNEL X-RAY SPECTRUM OF THE INSTRUMENT.
      "
    ITEMS                         = 512
    ITEM_BYTES                    = 4
  END_OBJECT                    = COLUMN

/* more COLUMN objects here */

END_OBJECT                    = TABLE
END

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In reply to Writing an ODL parser? by dHarry

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