Transform between braces & do/end when reflowing blocks?

[xeger]

I was rather surprised to see Syntax Tree make the following choice:

          expect(
            resulting_items.map { |i|
              { amount: i.amount }
            },
          ).to match(
            existing_model.fund.ownership_positions.current.map { |i|
              { amount: Float(i.id) }
            },
          )

It was preserving my choice of {} but when it reflowed the block to multiple lines, our convention normally would have been to switch to a do/end pair (and vice-versa).

As a workaround, I can Rubocop to auto-fix after formatting; it's a minor pain however. Is this a behavior that would be amenable to a Syntax Tree plugin? If so, perhaps I can work on contributing one to the core.

[kddnewton]

So it's doing that because it's trying to be careful. Normally it would happily convert to a do..end block. However, since you're inside of a Command node, it keeps the braces.

Here's an example of what I mean:

expect foo, bar { baz }

That works fine, but if baz is actually very long:

expect foo, bar do
  bazzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz
end

this actually changes the meaning to the block being given to the expect method instead of the bar method. So instead it detects that it's inside a command and keeps the braces. It does that here:

syntax_tree/lib/syntax_tree/node.rb

Lines 1974 to 1985 in 3f5b736

	# If this is nested anywhere inside certain nodes, then we can't change
	# which operators/keywords we're using for the bounds of the block.
	def unchangeable_bounds?(q)
	q.parents.any? do |parent|
	# If we hit a statements, then we're safe to use whatever since we
	# know for certain we're going to get split over multiple lines
	# anyway.
	break false if parent.is_a?(Statements)
	[Command, CommandCall].include?(parent.class)
	end
	end

To fix this, as it's walking up the tree is should notice that it's inside of a method call with parentheses (like it notices it's inside a statement list) and stop walking up the tree. That would fix this.

Feel like giving this one a shot?

[xeger]

I'll give it a try; thanks for the advice.