Two fixes for the _AlignTrailingComments(final_lines) function

[lizawang]

Hello all yapf founders!

I want to suggest two fixes for the _AlignTrailingComments(final_lines) function.

Two fixes

• When INDENT_DICTIONARY_VALUE is set True (default setting for yapf and google style), there will be pseudo parentheses added around dictionary values in the logical line, and they will be added when calculating the maximum line length before inline comment, but in output lines, the pseudo parentheses are excluded, so the following will happen:

  func( 1 )                                             # Line 1, the maximum length includes pseudo
  func( 2 )                                             # Line 2, the maximum length includes pseudo
  d = { key1: value1, key2: value2, key3: value3} # Line 3, but the pseudo parentheses are not shown
  func( 3 )                                             # Line 4, the maximum length includes pseudo
  func( 4 )                                             # line 5, the maximum length includes pseudo
  

  So when appending to the line content that is before the inline comment, do not include the pseudo
  parentheses around the dictionary values by changing the condition

  else:
    line_content += '{}{}'.format(whitespace_prefix, line_tok.value)
  

  into

  elif not line_tok.is_pseudo:
    line_content += '{}{}'.format(whitespace_prefix, line_tok.value)
  

• Fix the case when the existing space before the inline comment is larger than the padding spaces needed to align.
  Some edge cases (often happens to comments inside an object(e.g. a dictionary) logical line as following) when _AnalyzeSolutionSpace(state) is False for the logical line, the function _RetainHorizontalSpacing(lline) is called where spaces_required_before as a list is replaced with the actual spaces before the comment token. And if the number of the actual spaces before (aka the existing spaces before) the comment token is larger than the spaces needed to pad for alignment, the comment token will keep being added with the padding spaces and keep moving further towards right each time you run.

  func( 1 )               # Line 1
  func( 2 )               # Line 2
  d = {                    # line 3 comment 1 where the existing spaces before is 1 space larger than padded spaces
      key1: value1,       # line 3 comment2
      key2: value2,       # line 3 comment3
      key3: value3
  }                       # line 3 comment4
  
  

  The solution is to set the whitespace_prefix of the comment token into empty string when the number of
  existing spaces are larger:

  
  if len(existing_whitespace_prefix)>len(whitespace):
                    line_tok.whitespace_prefix = ''