This is a COBOL Copybook parser in Python featuring the following options:

• Parse the Copybook into a usable format to use in Python
• Clean up the Copybook by processing REDEFINES statements and remove unused definitions
• Denormalize the Copybook
• Write the cleaned Copybook in COBOL
• Strip prefixes of field names and ensure that the Copybook only contains unique names
• Can be used from the command-line or included in own Python projects

Because I couldn't find a COBOL Copybook parser that fitted all my needs I wrote my own. It doesn't support all functions found in the Copybook, just the ones that I met on my path: REDEFINES, INDEXED BY, OCCURS.

On a day to day basis I use it so that Informatica PowerCenter creates only 1 table of my COBOL data instead multiple.

The code uses the pic parser code from pyCOBOL.

This code is licensed under GPLv3.

The easiest way to install python-cobol is using pip:

$ pip install python-cobol

Below is an example Copybook file before and after being processed.

Before:

00000 * Example COBOL Copybook file AAAAAAAA 00000 01 PAULUS-EXAMPLE-GROUP. AAAAAAAA 00000 05 PAULUS-ANOTHER-GROUP OCCURS 0003 TIMES. AAAAAAAA 00000 10 PAULUS-FIELD-1 PIC X(3). AAAAAAAA 00000 10 PAULUS-FIELD-2 REDEFINES PAULUS-FIELD-1 PIC 9(3). AAAAAAAA 00000 10 PAULUS-FIELD-3 OCCURS 0002 TIMES AAAAAAAA 00000 PIC S9(3)V99. AAAAAAAA 00000 05 PAULUS-THIS-IS-ANOTHER-GROUP. AAAAAAAA 00000 10 PAULUS-YES PIC X(5). AAAAAAAA

After:

 01 EXAMPLE-GROUP. 05 FIELD-2-1 PIC 9(3). 05 FIELD-3-1-1 PIC S9(3)V99. 05 FIELD-3-1-2 PIC S9(3)V99. 05 FIELD-2-2 PIC 9(3). 05 FIELD-3-2-1 PIC S9(3)V99. 05 FIELD-3-2-2 PIC S9(3)V99. 05 FIELD-2-3 PIC 9(3). 05 FIELD-3-3-1 PIC S9(3)V99. 05 FIELD-3-3-2 PIC S9(3)V99. 05 THIS-IS-ANOTHER-GROUP. 10 YES PIC X(5). 

You can use it in two ways: inside your own python code or as a stand-alone command-line utility.

Do a git clone from the repository and inside your brand new python-cobol folder run:

$ python cobol.py example.cbl

This will process the redefines, denormalize the file, strip the prefixes and ensure all names are unique.

The utility allows for some command-line switches to disable some processing steps.

$ python cobol.py --help	usage: cobol.py [-h] [--skip-all-processing] [--skip-unique-names] [--skip-denormalize] [--skip-strip-prefix] filename	Parse COBOL Copybooks	positional arguments: filename The filename of the copybook.	optional arguments: -h, --help show this help message and exit --skip-all-processing Skips unique names, denormalization and . --skip-unique-names Skips making all names unique. --skip-denormalize Skips denormalizing the COBOL. --skip-strip-prefix Skips stripping the prefix from the names.

The parser can also be called from your Python code. All you need is a list of lines in COBOL Copybook format. See example.py how one would do it:

import cobol with open("example.cbl",'r') as f: for row in cobol.process_cobol(f.readlines()): print row['name']

It is also possible to call one of the more specialized functions within cobol.py:

• clean_cobol(lines)

  Cleans the COBOL by converting the cobol informaton to single lines

• parse_cobol(lines)

  Parses a list of COBOL field definitions into a list of dictionaries containing the parsed information.

• denormalize_cobol(lines)

  Denormalizes parsed COBOL lines

• clean_names(lines, ensure_unique_names=False, strip_prefix=False, make_database_safe=False)

  Cleans names of the fields in a list of parsed COBOL lines. Options to strip prefixes, enforce unique names and make the names database safe by converting dashes (-) to underscores (_)

• print_cobol(lines)

  Prints parsed COBOL lines in the Copybook format