Folding mechanism for while/for/if/switch-case

[jakub-suliga]

Problem:
Currently, there is no folding mechanism for while/for/if/switch-case statements in Eclipse. VSCode and IntelliJ support a folding mechanism for these statements. Therefore, I have created a method that implements this folding mechanism. This is also an open issue: #1426.

Before:

After:

How to test:

1. Start an Eclipse workspace and create a new class.
2. Add while/for/if/switch-case statements to this class.
3. Verify that the folding mechanism works as expected.

Here is a small program you can use to test:
public class SimpleProgram {
   public void checkNumber(int number) {
       if (number > 0) {
           System.out.println(number + " ist positiv.");
       } else {
           System.out.println(number + " ist null.");
       }
   }

   public static void main(String[] args) {
       SimpleProgram program = new SimpleProgram();
       int count = 1;
       while (count <= 5) {
           System.out.println("Count ist: " + count);
           count++;
       }
   }
}

Bugs:

• [Bug] [Folding mechanism] Method declaration on the Same Line as the Closing Bracket #1539
• When there are multiple nested while/for/if/switch-case statements, not all foldable regions are recognized.

[jakub-suliga]

@fedejeanne

[iloveeclipse]

FYI: the 23 test fails should be unrelated, I've just fixed last test that was failing on master after recent bigger changes on JDT core, so please rebase your branch on master if you want see whether your change breaks anything.

[iloveeclipse]

And btw, the feature looks cool.

[fedejeanne]

Thank you for contributing this, @jakub-suliga !

I tested it and it looks pretty good. I only have one improvement that I would like to add: the do-while loop and rename the new method to something more expressive.

One thing about the do-while loop is that it also suffers from #1539.

This is how it would look like if you include the do-while loop to this PR ...

... and fold it:

But that's a topic for another PR, I just wanted to point it out so it does not get forgotten.