Class: Yargi::Predicate

Inherits:
Object
  • Object
show all
Defined in:
lib/yargi/predicate.rb,
lib/yargi/predicate.rb

Overview

class IndexPredicate

Constant Summary collapse

ALL =

Predicates that always return true

TruePredicate.new
NONE =

Predicates that always return false

FalsePredicate.new

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.to_predicate(what = nil, &block) ⇒ Object

Builds a ‘what and block’ predicate, according the automatic conversions descibed above.



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# File 'lib/yargi/predicate.rb', line 20

def to_predicate(what=nil, &block)
  (what, block = block, nil) if what.nil?
  p = case what
    when Predicate
      what
    when Module
      TagPredicate.new(what)
    when Proc
      LambdaPredicate.new(&what)
    when TrueClass, NilClass
      ALL
    when FalseClass
      NONE
    when Integer
      IndexPredicate.new(what)
    else
      raise ArgumentError, "Unable to convert #{what} to a predicate"
  end
  if block
    p & LambdaPredicate.new(&block)
  else
    p
  end
end

Instance Method Details

#&(right) ⇒ Object

Builds a ‘self and right’ predicate



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# File 'lib/yargi/predicate.rb', line 47

def &(right)
  AndPredicate.new(*[self, Predicate.to_predicate(right)])
end

#not ⇒ Object

Builds a ‘not(self)’ predicate



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# File 'lib/yargi/predicate.rb', line 57

def not()
  NotPredicate.new(self)
end

#|(right) ⇒ Object

Builds a ‘self or right’ predicate



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# File 'lib/yargi/predicate.rb', line 52

def |(right)
  OrPredicate.new(*[self, Predicate.to_predicate(right)])
end