PR: Improve auto indentation of line following indented block

[pwoosam]

Fixes #3800

---

Added checkbox to editor's preferences to enable and disable "strict indent".

With strict indenting enabled, automatic indentation has the correct behavior expected in issue #3800.
Disabling strict indenting will have the same automatic indentation behavior as before the update.

[ccordoba12]

Very quick feedback: I don't agree with adding a configuration option for this. We just have to come with a more intelligent indentation algorithm.

By the way, this is the same indentation algorithm used in the Jupyter notebook (through Codemirror).

[ccordoba12]

Let's follow what VSCode and Sublime Text do: if the previous lines is unindented, leave the next line unindented too.

That way we won't need to add an option to control this indentation behavior and will fix #3800 too :-)

[ccordoba12]

Also, please merge your branch with the latest 3.x one to fix the errors in CircleCI

[pwoosam]

Yeah, I wasn't too sure whether or not to make this a configuration option or not. I wasn't sure if there was anyone out there that saw it as a feature. :p

And that sounds like a good plan, I'll get on it!

The algorithm has some other issues with multi-line statements too where it does not indent enough. I'll open an issue if there isn't already one.

[ccordoba12]

Thanks @pwoosam!

[ccordoba12]

Your work is breaking a test for indentation. Please review the failure in CircleCI to fix the problem :-)

[pwoosam]

@ccordoba12 It took me a while, but I finally got around to fixing the failure. However, I'm not completely confident that this code doesn't break any other auto indent features not covered in the tests.

When I was playing around with it, I also noticed that small mistakes could break other seemingly unrelated such as intelligent backspace.

[ccordoba12]

It'd be great if you could add a test for your work in widgets/sourcecode/tests/test_autoindent.py. Then we'll be sure of not breaking this feature in the future :-)

[pwoosam]

I actually did not completely fix tabs in 9c99ba4. It's having some issues indenting with tab. If the above line has no whitespace, it won't indent.

I'll try figuring out where I went wrong..

[pwoosam]

All I had to do was move a couple of lines down! Such a simple mistake!

I'm much more confident in this fix now :)

[ccordoba12]

@pwoosam, there's one use case I'd like to see implemented here too:

def f(x):
    return x
<Enter here (in empty/unindented line)>
<Leave next line unindented too, instead of moving cursor at the return indentation level>

[pwoosam]

@ccordoba12 Would you also like to unindent if you press return after a return statement just like it currently does with continue, break and pass?

[ccordoba12]

Would you also like to unindent if you press return after a return statement?

Yeah, that'd be great too! Thanks for thinking on it :-)

[pwoosam]

So currently the way I have this implemented for return statements is that it will automatically unindent the next line just like with break, continue and pass.

def f(x):\n
    return x\n
<new line starts here>

It also does as you asked:

def f(x):\n
    return x\n
\n
<new line starts here>

And it will also allow this:

def f(x):\n
    if x > 0:\n
        return x\n
\n          (it automatically unindented once and the user unindented once more)
<new line starts here>

This would also be useful for break, continue and pass. Here is an example for each:

def f(x):\n
    for i in range(x):\n
        if i % 90:\n
            print(i)\n
        else:\n
            break\n
\n           (it automatically unindented once and the user unindented twice more)
<new line starts here>

def f(x):\n
    for i in range(x):\n
        if i % 90:\n
            print(i)\n
        else:\n
            continue\n
\n          (it automatically unindented once and the user unindented twice more)
<new line starts here>

def f(x):\n
    if x > 0:\n
        pass\n
\n          (it automatically unindented once and the user unindented once more)
<new line starts here>

Currently they do:

def f(x):\n
    for i in range(x):\n
        if i % 90:\n
            print(i)\n
        else:\n
            break\n
\n
        <new line starts here>

def f(x):\n
    for i in range(x):\n
        if i % 90:\n
            print(i)\n
        else:\n
            continue\n
\n
        <new line starts here>

def f(x):\n
    if x > 0:\n
        pass\n
\n
    <new line starts here>

[pwoosam]

@ccordoba12 Let me know if you would like to see the above implemented for break, continue and pass as well. Otherwise, other than the print statement that I forgot to remove at line 1980, this is ready.

[ccordoba12]

@pwoosam, I have one final suggestion (and sorry if my previous example with return was not clear enough).

I just want to see that a return in any line that is unindented and blank, leaves the next line unindented too. That's how VSCode works and I find it a good approach :-)

[pwoosam]

@ccordoba12 Sorry, I'm not too familiar with VSCode and I was confused by the return statement. :p

I believe I've gotten the behavior you wanted now though!

It should keep the same indentation as the line you pressed enter on as long as that line was unindented(relative to the indentation of prevline) and blank.

This works great! It even does everything I wanted above! Simple and awesome :)

[ccordoba12]

@pwoosam, thanks a lot for the extra effort, it's working great now!

Hope to see more contributions from you in the future, you're doing great so far! ;-)