Add a new knob and a change for inline comment alignment

[lizawang]

Hello yapf founders! I want to share one knob and one change for the AlignTrailingComments feature.

The knob: ALIGN_NEWLINE_COMMENTS_WITH_INLINE_COMMENTS

This is a style option I added for when we do not want to align the newline comments with the inline comments in the same alignment block.

• This option is used together with the SPACE_BEFORE_COMMENT = a list of numbers.

• The default setting is True. When set to False, newline comments won't align with inline comments.

  For example, instead of

  if 1:
  encoding_bom = None
  if ( encoding.endswith( '-sig' ) or encoding.endswith( '-bom' ) ):
    encoding = encoding[ :-4 ]
    if ( encoding == 'utf-8' ):          # comment inline
                                         # comment newline
      encoding_bom = codecs.BOM_UTF16_BE
    else:
                                         #=========Comment Newlines=============================
                                         # I18N_MESSAGE | 210620850
                                         # de | BOM nicht unterstützt für Encoding '${enc}'.
                                         # en | BOM not supported for encoding '${enc}'.
                                         #======================================================
      result[ 'success' ] = False
      result[ 'error_code' ] = 210620850 # comment inline
  

  we want

  if 1:
  encoding_bom = None
  if ( encoding.endswith( '-sig' ) or encoding.endswith( '-bom' ) ):
    encoding = encoding[ :-4 ]
    if ( encoding == 'utf-8' ):          # comment inline
      # comment newline
      encoding_bom = codecs.BOM_UTF16_BE
    else:
      #=========Comment Newlines=============================
      # I18N_MESSAGE | 210620850
      # de | BOM nicht unterstützt für Encoding '${enc}'.
      # en | BOM not supported for encoding '${enc}'.
      #======================================================
      result[ 'success' ] = False
      result[ 'error_code' ] = 210620850 # comment inline
  

• A problem rises when using this new knob, instead of remaining the spaces before the standalone newline comment inside a logical line:

def f():
  result = {
      "a": 1,
      # comment
      "abc": 2
  }

The comment is dedented to its parent level like:

def f():
  result = {
      "a": 1,
  # comment
      "abc": 2
  }

This is also fixed by adding one line in _GetNewlineColumn(self), restricting to set the spaces before the comment to 0 only when it’s not inside a logical line(aka with parent_level==0).

One change

Another change I added is when there is an object(dictionary, argument list, list, function call) with its entries on separate lines with its closing bracket also on a separate line, it starts a new alignment block. For example:

func( 1 )               # Line 1
func( 2 )               # Line 2
d = {
    key1: value1,
    key2: value2,
    key3: value3,
}                       # Line 3
func( 3 )     # Line 4
func( 4 )     # line 5

Finally

• The knob is added in style.py. The default setting is True.
• The tests for the new knob and new alignment after the object with entries on separate lines are added in yapf_test.py. All yapftests are run and no test fail is caused by the changes.