feat: add support for auto-closing brackets/quotations in the REPL

[Snehil-Shah]

Resolves #1672

Description

What is the purpose of this pull request?

This pull request:

• Implements auto-closing of brackets and quotations in the REPL.

• Adds option to toggle this behavior.

• Adds support for modifier key to add newline for multi-line editing

Related Issues

Does this pull request have any related issues?

This pull request:

• resolves [RFC]: add auto-closing brackets and quotations in REPL #1672
• relates to [Idea]: building a better Node.js REPL google-summer-of-code#1

Other

Any other information relevant to this pull request? This may include screenshots, references, and/or implementation notes.

For Multi-line editing, I have used ALT+ENTER as the modifier key.

This might seem odd given SHIFT+ENTER is the conventional key combination to add a newline instead of executing a command, but it is done because the terminal or the readline module cannot differentiate between ENTER & SHIFT+ENTER or even CTRL+ENTER.

ALT+ENTER generates a different keypress value than the others.

Questions

Any questions for reviewers of this pull request?

I am utilizing readline module's private methods (shown in image) to mess with the input stream. Public apis like write() or cursorTo() aren't working as expected.

I am not entirely sure if it's okay to use these private methods, but they definitely work as desired.

UPDATE: Solved!

Checklist

Please ensure the following tasks are completed before submitting this pull request.

• Read, understood, and followed the contributing guidelines.

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@stdlib-js/reviewers

[Snehil-Shah]

@kgryte maybe we can also add a keyboard shortcut to toggle this behaviour?

[kgryte]

@Snehil-Shah Atm, we don't have any support for keyboard shortcuts in the REPL, so I'd like to avoid adding anything like that here. Adding keyboard shortcuts is a future concern, but needs to be addressed more holistically (e.g., vim, Sublime Text, etc, keybindings).

[kgryte]

Left some initial comments.

[Snehil-Shah]

@kgryte IPython uses CTRL+O to manually add multi-line, maybe we can add that too on top of ALT+ENTER?

[kgryte]

Hmm...CTRL+O is not obvious to me. I think people are more likely to be used to chat apps which use CMD or SHIFT as the modifier with ENTER.

[Snehil-Shah]

@kgryte improved the manual multi-line editing by making it cursor-aware.

when manually adding a newline (using alt+enter), it adds a newline from the cursor position just like a text editor would!

is this okay?

[Snehil-Shah]

@kgryte Made auto-closing symbols more ergonomic by handling the case where the user instinctively adds a closing bracket when typing with flow. The extra closing symbol is discarded similar to IDEs.

[kgryte]

@Snehil-Shah Thanks for adding auto-delete tests!

[kgryte]

Another thing is do we need two separate settings for auto-deletion and auto-closing? Aren't both generally considered part of the same feature?

They are certainly related, but, while often they are implemented together, IMO they are still distinct. As a user, I may want auto-deletion, but not auto-closing because I may find auto-insertion annoying or want more fine-grained control as to when characters are inserted. And vice versa. For auto-deletion in particular, if I typed [] and then only want to delete the [, I need to resort to odd little workarounds (e.g., first inserting a space between the characters or deleting and then retyping ], etc). That may be enough for users to prefer one behavior but not the other.

[kgryte]

We can just use regex in this case to check the character just before/after the symbol like I did before.

Ah, okay, that was why you had that logic in there; I wasn't able to figure out from the comments alone what the intent was. But also, the regexp approach was too limited, as string content can be more than just ASCII. I think I have a solution for this and can push up a fix later today.

[kgryte]

@Snehil-Shah Okay. I think this is in a pretty good state. You mind doing a final review to check that we didn't miss anything?

[Snehil-Shah]

@kgryte Checked everything, looks good to go👍

[kgryte]

@Snehil-Shah Thanks for checking! Let's go ahead and get this in. Any subsequent work can be addressed in follow-up PRs. Thanks for your work on this; this is really nice functionality to have.