Modify foldEndPattern in Atom settings

[kylebarron]

(This is in conjunction with a similar PR sent to language-python atom/language-python#274, though the text is modified slightly for MagicPython)

Description of the Change

Add a value for foldEndPattern in the package settings. This improves the folding behavior for dictionaries, lists, and functions. It folds the entire logical syntax item instead of leaving the ending character on a separate line. It also improves the use of Hydrogen when the ending }, ), or ] is on a separate line and not indented.

Many other core Atom language grammars have a foldEndPattern; the regex used in this PR is taken from language-javascript because of the similarity in syntax used for data structures.

Alternate Designs

The regex is ^\\s*\\}|^\\s*\\]|^\\s*\\) in order to fold the end of dictionaries, lists, and functions/tuples, respectively.

The current foldEndPattern in MagicPython is ^\\s*"""\\s*$. The language-python foldEndPattern used to be the same but was removed because the fold would include the beginning """ here:

if True:
    print(True)

"""
A string"""

Since Hydrogen uses Atom's fold regions to determine what code to send to the kernel, it also ran """, which was undesirable.

Benefits

1. Improve fold behavior by including the ending character (see screenshots below)

Expanded:

Current fold behavior:

New fold behavior:

2. This would also improve behavior with the Hydrogen package, as that uses Atom's fold regions to decide what block of code to send to the Jupyter kernel. A hacky solution to this was developed (read executed line to get indentation level and expand code nikitakit/hydrogen-python#10, code) in a Python-specific extension to Hydrogen, but the plugin's use is not widespread among all Hydrogen Python users.

Current Hydrogen behavior with ending character on separate line:

New Hydrogen behavior with ending character on separate line:

Possible Drawbacks

Those who prefer the current behavior could be disappointed? I can't think of any others.

Applicable Issues

• Atom/Hydrogen plugin: SyntaxError when creating multi-line dictionaries #80
• SyntaxError when creating multi-line dictionaries nteract/hydrogen#724
• code is only considered a block if indent is maintained nteract/hydrogen#155

[1st1]

LGTM. @vpetrovykh please take a look

[vpetrovykh]

Looks good. Thanks for the detailed explanation and examples!

[kylebarron]

Thanks! It appears that there hasn't been a release since August 2017. Do you have any idea for a timeline of when the next release might happen?

[1st1]

I'll cut the next release sometime next week. Thanks!