Class: TextAlignment::AnchorFinder

Inherits:
Object
  • Object
show all
Defined in:
lib/text_alignment/anchor_finder.rb

Instance Method Summary collapse

Constructor Details

#initialize(source_str, target_str, cultivation_map, to_ignore_whitespaces = false, to_ignore_text_order = false) ⇒ AnchorFinder

Returns a new instance of AnchorFinder.



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# File 'lib/text_alignment/anchor_finder.rb', line 9

def initialize(source_str, target_str, cultivation_map, to_ignore_whitespaces = false, to_ignore_text_order = false)
	@method_get_left_windows, @method_get_right_windows = if to_ignore_whitespaces
		[method(:get_left_windows_no_squeeze_ws), method(:get_right_windows_no_squeeze_ws)]
	else
		[method(:get_left_windows), method(:get_right_windows)]
	end

	@s1 = source_str.downcase
	@s2 = target_str.downcase

	@cultivation_map = cultivation_map
	@to_ignore_text_order = to_ignore_text_order

	@size_ngram  = TextAlignment::SIZE_NGRAM
	@size_window = TextAlignment::SIZE_WINDOW
	@sim_threshold = TextAlignment::TEXT_SIMILARITY_THRESHOLD
	@pos_s1_final_possible_begin = @s1.length - @size_ngram - 1
	@pos_s2_final_possible_end = @s2.length

	# positions of last match
	@pos_s1_last_match = 0
	@pos_s2_last_match = 0
end

Instance Method Details

#get_next_anchor ⇒ Object 



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# File 'lib/text_alignment/anchor_finder.rb', line 33

def get_next_anchor
	# To find the beginning positions of an anchor ngram in s1 and s2, beginning from the last positions matched
	beg_s2 = for beg_s1 in @pos_s1_last_match .. @pos_s1_final_possible_begin

		# To skip whitespace letters
		next if [' ', "\n", "\t"].include? @s1[beg_s1]

		_beg_s2 = get_beg_s2(beg_s1)
		break _beg_s2 unless _beg_s2.nil?
	end

	# To return nil when it fails to find an anchor
	return nil if beg_s2.class == Range

	# To extend the block to the left
	b1 = beg_s1
	b2 = beg_s2
	left_boundary_b2 = [@pos_s2_last_match, (@cultivation_map.last_cultivated_position(b2) || 0)].max
	while b1 > @pos_s1_last_match && b2 > left_boundary_b2 && @s1[b1 - 1] == @s2[b2 - 1]
		b1 -= 1; b2 -= 1
	end

	# To extend the block to the right
	e1 = beg_s1 + @size_ngram
	e2 = beg_s2 + @size_ngram
	right_boundary_b2 = @cultivation_map.next_cultivated_position(e2) || @pos_s2_final_possible_end
	while @s1[e1] && e2 < right_boundary_b2 && @s1[e1] == @s2[e2]
		e1 += 1; e2 += 1
	end

	@pos_s1_last_match = e1
	@pos_s2_last_match = e2

	{source:{begin:b1 , end:e1}, target:{begin:b2, end:e2}}
end