100 lines
2.5 KiB
Ruby
100 lines
2.5 KiB
Ruby
# frozen_string_literal: true
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# transforms "english like" text queries into a tsquery operation
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# https://www.postgresql.org/docs/9.5/textsearch-controls.html#TEXTSEARCH-PARSING-QUERIES
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class TextToTsquery
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attr_reader :text
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def initialize(text, wildcard: true)
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@text = text.to_s.strip
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@wildcard = wildcard
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@exact_matches = []
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validate!
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end
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EXACT_WORD_CHAR = '§'.freeze
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def tsquery
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@tsquery = @text
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strip_exact_words
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remove_duplicated_spaces
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transform_or_into_operator
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transform_and_into_operator
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strip_spaces_from_parenthesis
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transform_remaining_spaces_into_and_operator
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transform_keywords
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join_operators_with_and
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remove_partial_match_from_not_keywords
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add_exact_words
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@tsquery
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end
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def validate!
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parenthesis_error unless self.class.valid_search_parenthesis?(@text)
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end
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def self.valid_search_parenthesis?(text)
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text.split('').reduce(0) do |acc, char|
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return false if acc < 0
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if char == '('
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acc + 1
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elsif char == ')'
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acc - 1
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else
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acc
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end
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end.zero?
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end
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def parenthesis_error
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raise ArgumentError, "incorrect number/order of parenthesis in search query: '#{@text}'"
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end
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def strip_exact_words
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@exact_matches << Regexp.last_match(1) while @tsquery.sub!(/"(.*?)"/, EXACT_WORD_CHAR)
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end
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def remove_duplicated_spaces
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@tsquery = @tsquery.gsub(/\s+/, ' ')
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end
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# transforms or/OR/|/|| into | operator
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def transform_or_into_operator
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@tsquery = @tsquery.gsub(/ ((or|\|+) )+/i, '|').gsub(/ *\|+ */, '|')
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end
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# transforms and/AND/&/&& into & operator
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def transform_and_into_operator
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@tsquery = @tsquery.gsub(/ ((and|\&+) )+/i, '&')
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end
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def strip_spaces_from_parenthesis
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@tsquery = @tsquery.gsub(/ *([()]) */, '\1')
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end
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def transform_remaining_spaces_into_and_operator
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@tsquery = @tsquery.tr(' ', '&')
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end
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# adds :* for partial match of words
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def transform_keywords
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keyword = @wildcard ? '\1:*' : '\1:'
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@tsquery = @tsquery.gsub(/([^#{EXACT_WORD_CHAR}|&!())]+)/, keyword)
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end
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# adds & between operations
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def join_operators_with_and
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@tsquery = @tsquery.gsub(/:(\**)\!/, ':\1&!').gsub(/:(\**)\(/, ':\1&(').gsub(/\&+/, '&')
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end
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# removes partial match from NOT operations
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def remove_partial_match_from_not_keywords
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@tsquery = @tsquery.gsub(/\!([^|&!())]+):\**/, '!\1')
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end
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def add_exact_words
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@exact_matches.each { |phrase| @tsquery = @tsquery.sub(EXACT_WORD_CHAR, "'#{phrase}'") }
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end
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end
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