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# module for classes needed to test TreeSpellChecker
module TreeSpell
require_relative 'change_word'
# Simulate an error prone human typist
# see doc/human_typo_api.md for the api description
class HumanTypo
def initialize(input, lambda: 0.05)
@input = input
check_input
@len = input.length
@lambda = lambda
end
def call
@word = input.dup
i_place = initialize_i_place
loop do
action = action_type
@word = make_change action, i_place
@len = word.length
i_place += exponential
break if i_place >= len
end
word
end
private
attr_accessor :input, :word, :len, :lambda
def initialize_i_place
i_place = nil
loop do
i_place = exponential
break if i_place < len
end
i_place
end
def exponential
(rand / (lambda / 2)).to_i
end
def rand_char
popular_chars = alphabetic_characters + special_characters
n = popular_chars.length
popular_chars[rand(n)]
end
def alphabetic_characters
('a'..'z').to_a.join + ('A'..'Z').to_a.join
end
def special_characters
'?<>,.!`+=-_":;@#$%^&*()'
end
def toss
return +1 if rand >= 0.5
-1
end
def action_type
[:insert, :transpose, :delete, :substitute][rand(4)]
end
def make_change(action, i_place)
cw = ChangeWord.new(word)
case action
when :delete
cw.deletion(i_place)
when :insert
cw.insertion(i_place, rand_char)
when :substitute
cw.substitution(i_place, rand_char)
when :transpose
cw.transposition(i_place, toss)
end
end
def check_input
fail check_input_message if input.nil? || input.length < 5
end
def check_input_message
"input length must be greater than 5 characters: #{input}"
end
end
end
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