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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
POPULAR_CHARS = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ?<>,.!`+=-_":;@#$%^&*()'.split("").freeze
ACTION_TYPES = %i(insert transpose delete substitute).freeze
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_TYPES.sample
@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 make_change(action, i_place)
cw = ChangeWord.new(word)
case action
when :delete
cw.deletion(i_place)
when :insert
cw.insertion(i_place, POPULAR_CHARS.sample)
when :substitute
cw.substitution(i_place, POPULAR_CHARS.sample)
when :transpose
cw.transposition(i_place, rand >= 0.5 ? +1 : -1)
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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