Lazy parsing of calendars

[niccokunzmann]

Closes issue

• Lazy parsing #158
• Lazy subcomponent parsing for large calendars #1050
• Parametrize test suite to run with both Calendar and LazyCalendar #1093

Inspired by #1090

Description

• move Component.from_ical into a class.
• create subclass to re-parse components in case the calendar has timezone forward references

Checklist

• I've added a change log entry to CHANGES.rst.
• I've added or updated tests if applicable.
• I've run and ensured all tests pass locally by following Run tests.
• I've added or edited documentation, both as docstrings to be rendered in the API documentation and narrative documentation, as necessary.

---

📚 Documentation preview 📚: https://icalendar--1201.org.readthedocs.build/

[coveralls]

Pull Request Test Coverage Report for Build 22078704268

Details

• 265 of 278 (95.32%) changed or added relevant lines in 11 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.04%) to 98.053%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/icalendar/parser/ical/lazy.py	43	44	97.73%
src/icalendar/parser/ical/component.py	112	117	95.73%
src/icalendar/cal/lazy.py	25	32	78.13%

Totals
Change from base Build 22032008571:	-0.04%
Covered Lines:	11541
Relevant Lines:	11762

---

💛 - Coveralls

[SashankBhamidi]

Just saw this, I don't want #1050 to be closed, that'd effect my GitHub stats, can it be merged and worked upon?

[niccokunzmann]

Yes, at some point, you could add some tests to this PR. I will not copy from your PR then, so you can add some of your stuff. Also, I wonder what you are optimizing for, not closing PRs, but that is not my business :)

[SashankBhamidi]

Yes, at some point, you could add some tests to this PR. I will not copy from your PR then, so you can add some of your stuff. Also, I wonder what you are optimizing for, not closing PRs, but that is not my business :)

Oh wait, my bad, I meant #1090, I mis-read "Inspired" as "Closes" haha. Apologies.

Lmk when you want me to add stuff here and ready for review.

[niccokunzmann]

@SashankBhamidi Thanks for the review. There are outstanding tasks

• Lazy parsing of calendars #1201 (comment)
• Lazy parsing of calendars #1201 (comment)
• Lazy parsing of calendars #1201 (comment)

How should we go about this and the other PR. Would you want to PR it to this branch and we merge it into this one?

[SashankBhamidi]

Thanks for the review. There are outstanding tasks

I'd prefer to keep #1090 open and rebase it on top once this merges. Can we agree on that path before I mark this approved?

[SashankBhamidi]

@niccokunzmann I've left my comments on the tasks.

[niccokunzmann]

I'd prefer to keep #1090 open and rebase it on top once this merges. Can we agree on that path before I mark this approved?

Yes, that sounds good.

[niccokunzmann]

@SashankBhamidi @stevepiercy I believe, I addressed all your comments. Could you have a look again?

[SashankBhamidi]

@niccokunzmann component.py has conflicts, I will review by EOD.

[SashankBhamidi]

There's a duplicate return self._subcomponents.is_lazy() at lines 263-264 in cal/lazy.py, looks like it crept in during the edits. One of them needs to go.

Good work, thanks!

[niccokunzmann]

1bd35c0 addresses the duplicated statement

Merge?

[SashankBhamidi]

LGTM, can be merged unless @stevepiercy has something to add.