Class: ExpressionFactory

Inherits:
Object
  • Object
show all
Includes:
Logue::Loggable
Defined in:
lib/glark/match/factory.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(matchspec) ⇒ ExpressionFactory

Returns a new instance of ExpressionFactory.



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# File 'lib/glark/match/factory.rb', line 20

def initialize matchspec
  @regexp_factory = RegexpExpressionFactory.new matchspec
end

Instance Attribute Details

#expr ⇒ Object (readonly)

Returns the value of attribute expr.



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# File 'lib/glark/match/factory.rb', line 18

def expr
  @expr
end

Instance Method Details

#make_and_distance(arg, args) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 94

def make_and_distance arg, args
  adist = AndDistance.new arg, args
  adist.distance
end

#make_and_expression(arg, args) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 99

def make_and_expression arg, args
  dist = make_and_distance arg, args

  a1, a2 = make_two_expressions args, "and"
  AndExpression.new dist, a1, a2
end

#make_expression(args, warn_option = false) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 143

def make_expression args, warn_option = false
  arg = args[0]
  
  if arg
    case arg
    when "--or", "-o"
      args.shift
      make_or_expression args
    when "--xor"
      args.shift
      make_xor_expression args
    when %r{^\-\-and}, %r{^\-a}
      args.shift
      make_and_expression arg, args
    when '('
      args.shift
      make_infix_expression arg, args
    else
      if warn_option && arg.index(%r{^\-{1,2}\w})
        raise "option not understood: #{arg}"
      end

      args.shift
      make_regular_expression arg
    end
  else
    nil
  end
end

#make_expressions(args) ⇒ Object

creates two expressions and returns them.



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# File 'lib/glark/match/factory.rb', line 50

def make_expressions args
  a1 = make_expression args
  a2 = make_expression args
  
  [ a1, a2 ]
end

#make_infix_expression(arg, args = []) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 106

def make_infix_expression arg, args = []
  expr = nil

  while arg
    case arg
    when '('
      arg  = args.shift
      expr = make_infix_expression arg, args
    when '--or', '-o'
      arg  = args.shift
      rhs  = make_infix_expression arg, args
      expr = InclusiveOrExpression.new expr, rhs
    when '--xor'
      arg  = args.shift
      rhs  = make_infix_expression arg, args
      expr = ExclusiveOrExpression.new expr, rhs
    when Regexp.new('^--and'), '-a'
      dist = make_and_distance arg, args
      arg  = args.shift
      rhs  = make_infix_expression arg, args
      expr = AndExpression.new dist, expr, rhs
    when ')'
      break
    else
      expr = make_regular_expression arg
      break
    end
    arg = args.shift
  end

  if !expr
    raise "No expression provided."
  end

  expr
end

#make_not_expression(args) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 63

def make_not_expression args
  expr = make_regular_expression args, true
  unless expr
    raise "'not' expression takes one argument"
  end

  # explicit end tag is optional:
  shift_end_tag "not", args
  expr
end

#make_or_expression(args) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 84

def make_or_expression args
  a1, a2 = make_two_expressions args, "or"
  InclusiveOrExpression.new a1, a2
end

#make_regular_expression(pattern, negated = false) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 45

def make_regular_expression pattern, negated = false
  @regexp_factory.create_expression pattern, negated
end

#make_two_expressions(args, type) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 74

def make_two_expressions args, type
  a1, a2 = make_expressions args
  unless a1 && a2
    raise "'" + type + "' expression takes two arguments"
  end

  shift_end_tag type, args
  [ a1, a2 ]
end

#make_xor_expression(args) ⇒ Object 



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# File 'lib/glark/match/factory.rb', line 89

def make_xor_expression args
  a1, a2 = make_two_expressions args, "xor"
  ExclusiveOrExpression.new a1, a2
end

#read_file(fname) ⇒ Object

reads a file containing one regular expression per line.



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# File 'lib/glark/match/factory.rb', line 25

def read_file fname
  expr = nil
  File.open(fname) do |file|
    file.each_line do |line|
      line.strip!
      next if line.empty?

      # flatten the or expression instead of nesting it, to avoid
      # stack overruns for very large files.
      re = make_regular_expression line.chomp
      if expr 
        expr.ops << re
      else
        expr = InclusiveOrExpression.new re
      end
    end
  end
  expr
end

#shift_end_tag(name, args) ⇒ Object

removes optional end tag



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# File 'lib/glark/match/factory.rb', line 58

def shift_end_tag name, args
  # explicit end tag is optional:
  args.shift if args[0] == ("--end-of-" + name)
end