Class: JGrep::Scanner

Inherits:
Object
  • Object
show all
Defined in:
lib/parser/scanner.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(arguments) ⇒ Scanner

Returns a new instance of Scanner.



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# File 'lib/parser/scanner.rb', line 5

def initialize(arguments)
  @token_index = 0
  @arguments = arguments
end

Instance Attribute Details

#arguments ⇒ Object

Returns the value of attribute arguments.



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# File 'lib/parser/scanner.rb', line 3

def arguments
  @arguments
end

#token_index ⇒ Object

Returns the value of attribute token_index.



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# File 'lib/parser/scanner.rb', line 3

def token_index
  @token_index
end

Instance Method Details

#get_token ⇒ Object

Scans the input string and identifies single language tokens



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# File 'lib/parser/scanner.rb', line 11

def get_token
  return nil if @token_index >= @arguments.size

  begin
    case chr(@arguments[@token_index])
    when "["
      return "statement", gen_substatement

    when "]"
      return "]"

    when "("
      return "(", "("

    when ")"
      return ")", ")"

    when "n"
      if (chr(@arguments[@token_index + 1]) == "o") && (chr(@arguments[@token_index + 2]) == "t") && ((chr(@arguments[@token_index + 3]) == " ") || (chr(@arguments[@token_index + 3]) == "("))
        @token_index += 2
        return "not", "not"
      else
        gen_statement
      end

    when "!"
      return "not", "not"

    when "a"
      if (chr(@arguments[@token_index + 1]) == "n") && (chr(@arguments[@token_index + 2]) == "d") && ((chr(@arguments[@token_index + 3]) == " ") || (chr(@arguments[@token_index + 3]) == "("))
        @token_index += 2
        return "and", "and"
      else
        gen_statement
      end

    when "&"
      if chr(@arguments[@token_index + 1]) == "&"
        @token_index += 1
        return "and", "and"
      else
        gen_statement
      end

    when "o"
      if (chr(@arguments[@token_index + 1]) == "r") && ((chr(@arguments[@token_index + 2]) == " ") || (chr(@arguments[@token_index + 2]) == "("))
        @token_index += 1
        return "or", "or"
      else
        gen_statement
      end

    when "|"
      if chr(@arguments[@token_index + 1]) == "|"
        @token_index += 1
        return "or", "or"
      else
        gen_statement
      end

    when "+"
      value = ""
      i = @token_index + 1

      begin
        value += chr(@arguments[i])
        i += 1
      end until (i >= @arguments.size) || (chr(@arguments[i]) =~ /\s|\)/)

      @token_index = i - 1
      return "+", value

    when "-"
      value = ""
      i = @token_index + 1

      begin
        value += chr(@arguments[i])
        i += 1
      end until (i >= @arguments.size) || (chr(@arguments[i]) =~ /\s|\)/)

      @token_index = i - 1
      return "-", value

    when " "
      return " ", " "

    else
      gen_statement
    end
  end
rescue NoMethodError
  raise "Error. Expression cannot be parsed."
end