Class: BomDB::Diff::Aligner

Inherits:
Object
  • Object
show all
Defined in:
lib/bomdb/diff/aligner.rb

Constant Summary collapse

DIFF_RE = 
/\{(\+|\-)(.+?)\1\}/
INSERT_RE = 
/\{\+(.+?)\+\}/
VERSE_RE = 
/\[\|([^\]]+)\|\]/

Class Method Summary collapse

Class Method Details

.parse(diff_text) ⇒ Object 



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# File 'lib/bomdb/diff/aligner.rb', line 39

def self.parse(diff_text)
  scanner = StringScanner.new(diff_text)

  output = ""

  last_pos = 0
  while !scanner.eos?
    if scanner.scan_until(DIFF_RE)
      output << scanner.pre_match[last_pos..-1]
      last_pos = scanner.pos
      
      diff_match = DIFF_RE.match(scanner.matched)
      case diff_match[1]
      when '-' then # this is a deletion
        inner = diff_match[2]
        # the only deletions we care about are those with verse headings inside them
        if verse_match = VERSE_RE.match(inner)
          output << parse_verse_heading(scanner, inner, verse_match)
          last_pos = scanner.pos
        end
      when '+' then # this is an insertion
        output << diff_match[2]
      end
    else
      output << scanner.rest
      break
    end
  end

  return output
end

.parse_verse_heading(scanner, deletion, verse_match) ⇒ Object 



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# File 'lib/bomdb/diff/aligner.rb', line 10

def self.parse_verse_heading(scanner, deletion, verse_match)
  # the text of the verse, e.g. "1 Nephi 1:1"
  verse = verse_match[1]

  # the range of the verse capture, e.g. [2, 17] from ". [|1 Nephi 1:1|]Yea"
  verse_capture_slice = Range.new(*verse_match.offset(0), true)

  # the deletion without the verse, e.g. ". Yea"
  deletion_without_verse = deletion.clone
  deletion_without_verse.slice!(verse_capture_slice)

  # if there's an insertion immediately following...
  if scanner.scan(INSERT_RE)
    insertion = scanner.matched.match(INSERT_RE)[1]
    insert_pos = verse_match.offset(0).first

    # if the match, without the verse heading, is the same size as its
    # substitution, then concat the pre_match, add the verse heading, and
    # concat the post_match
    if insertion.size > insert_pos
      insertion[0...insert_pos] + "\n" + verse + insertion[(insert_pos-1)..-1]
    else
      insertion[0...insert_pos] + "\n" + verse
    end
  else
    "\n" + verse
  end
end