Add support for removing lines in Parser::Source::Rewriter

[dblock]

Currently lib/parser/source/rewriter.rb doesn't support remove with a range that spans multiple lines.

I was trying to implement a corrector for empty lines in Rubocop, dblock/rubocop@8d7f401.

[whitequark]

Theoretically that should work, rewriter doesn't care about newlines. Can you post a testcase?

[dblock]

It works, my bad. PRed the test that confirms that. Debugging where the issue really is.

[dblock]

I don't think I quite understand what's going on here, so lets backup. The exception I get is:

RangeError:
       #<Parser::Source::Range (string) 10...11> spans more than one line
     # ./lib/rubocop/cop/corrector.rb:58:in `remove'

The code that throws this is here, but I cannot repro this outside of Rubocop.

It works with a buffer like this:

#<Parser::Source::Buffer:0x007fc972a95b30 @name="(string)", @source="test = 5\n\n\n\ntop", @first_line=1, @lines=nil, @line_begins=nil>

It fails with a buffer like this:

#<Parser::Source::Buffer:0x007fc972a95b30 @name="(string)", @source="test = 5\n\n\n\ntop", @first_line=1, @lines=nil, @line_begins=[[4, 12], [3, 11], [2, 10], [1, 9], [0, 0]]>

I tried at no avail to construct the latter and repro the exception.

[whitequark]

You can convert the former buffer into the latter by forcing it to calculate line begins, which usually is done lazily, e.g. for calling #line_begins. (Duh.)

The error you're seeing is raised in Range#column_range. That method is only called from Diagnostic#render by Parser itself.

[whitequark]

Still a problem?

[dblock]

This was an issue between the computer and the chair, closing. Thanks for your help!