Added support for renaming duplicate headers

[fortydegrees]

Added code to automatically rename headers to solve the issue in #129

I tried to add a renameDuplicateHeaders config option but left it out as I am doing the processing in the Parse.parse function where I don't have the ability to read the config. I'm not sure it fits the styling of the codebase to modify the input outside of that function so have left it out.

[pokoli]

Hi Thanks for creating the PR.

As starting point we need to have a test case (not a test file). This means creating a function on tests/test-cases.js with a simple file that demostrates the functiona.

I have some concerns about your code:

• There are prints and other comments that are uselless. Could you please remove them?
• We have an option to decide if the file has a header or not but your code is always executed no mather if the header is disabled.
• There is a while loop inside the for that it seems to me that can be simplified.

Could you please address such issues? Thanks

[fortydegrees]

Thanks for the quick feedback & sorry for the misunderstanding re: test cases.

I've added a test case, removed the useless comments, and added a conditional based on whether the header is present.

You were right - the renaming code could be refactored. I originally just took the code from that issue thread which worked but was inefficient. I've rewritten it in a simpler way which produces the same result.

[pokoli]

Thanks for your work on this. Everything looks nice, I just added some comments to improve code redability and ensure everything works as expected. Could you please review them?

[fortydegrees]

Have addressed all comments re: code-cleanup.

Good call on the transformHeader() test. I added it and It originally failed. I added a check for the function when initialising the header in my code. Hopefully this is satisfactory.

I also added an extra test in the case of an existing header matching an intended substitution. An unlikely situation but thought it'd be wise to cover it.

[pokoli]

Everythinkg looks nice now. I leaved some minor issues that should be addressed.

Could you fix them? I think we will be able to merge it once they are addressed.

Thanks for your time on this.

[pokoli]

I think its simpler to write as:

count = header_count[header_name] || '1';
header_name = header+separator+count;
header_count[header_name] = count +1;

Removeing the if else lines.

[fortydegrees]

I struggled to make it work without an if statement. The problem being that it would still add the suffix at the end. The best I got was:

let count = header_count[header] || 0
if (count > 0) header_name = header+separator+count;
header_count[header] = count+1

Have committed this for you consideration if you prefer.

[pokoli]

@fortydegrees linting is failing, could you have a look?

https://github.com/mholt/PapaParse/actions/runs/3463298598/jobs/5783355405

[fortydegrees]

@fortydegrees linting is failing, could you have a look?

https://github.com/mholt/PapaParse/actions/runs/3463298598/jobs/5783355405

Should be fixed now. Thank you for your excellent help in cleaning everything up!

[pokoli]

@fortydegrees I've merged your work. Thanks you so much!

[sethmcleod]

Thank you for resolving this @fortydegrees!

@pokoli Would you mind doing another minor version bump so we can use these changes in production?