Class: J8::Optional

Inherits:
Object show all
Includes:
Common
Defined in:
lib/j8/optional.rb

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Common

callable_from_proc, from_callable, from_callable_class, initialize, lambda?, make_lambda, raise_unless_lambda

Constructor Details

#initialize(value = nil) ⇒ Optional

Returns a new instance of Optional.



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# File 'lib/j8/optional.rb', line 7

def initialize(value = nil)
  @value = value
end

Class Method Details

.empty ⇒ Object 



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# File 'lib/j8/optional.rb', line 11

def self.empty
  J8::Optional.new
end

.of(value) ⇒ Object

Raises:



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# File 'lib/j8/optional.rb', line 15

def self.of(value)
  raise J8::NilException if value.nil?

  J8::Optional.new(value)
end

.of_nilable(value) ⇒ Object 



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# File 'lib/j8/optional.rb', line 21

def self.of_nilable(value)
  J8::Optional.new(value)
end

Instance Method Details

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/j8/optional.rb', line 25

def empty?
  @value.nil?
end

#equals?(object) ⇒ Boolean Also known as: ==

Returns:

  • (Boolean) 


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# File 'lib/j8/optional.rb', line 29

def equals?(object)
  @value == object
end

#filter(predicate = nil, &block) ⇒ Object 



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# File 'lib/j8/optional.rb', line 34

def filter(predicate = nil, &block)
  callable = from_callable_class(predicate, block, J8::Predicate)

  if present? && callable.test(@value)
    J8::Optional.new(@value)
  else
    J8::Optional.empty
  end
end

#flat_map(function = nil, &block) ⇒ Object 



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# File 'lib/j8/optional.rb', line 44

def flat_map(function = nil, &block)
  callable = from_callable_class(function, block, J8::Function)
  return J8::Optional.empty unless present?

  callable.apply(@value).tap do |result|
    raise J8::NilException if result.nil?
  end
end

#get ⇒ Object Also known as: value

Raises:



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# File 'lib/j8/optional.rb', line 53

def get
  raise J8::NoSuchElementException unless present?

  @value
end

#if_present(consumer = nil, &block) ⇒ Object 



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# File 'lib/j8/optional.rb', line 60

def if_present(consumer = nil, &block)
  callable = from_callable_class(consumer, block, J8::Consumer)
  return unless present?

  callable.accept(@value)
end

#map(function = nil, &block) ⇒ Object 



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# File 'lib/j8/optional.rb', line 71

def map(function = nil, &block)
  callable = from_callable_class(function, block, J8::Function)
  return J8::Optional.empty unless present?

  J8::Optional.new(callable.apply(@value))
end

#or_else(value) ⇒ Object 



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# File 'lib/j8/optional.rb', line 78

def or_else(value)
  if present?
    @value
  else
    value
  end
end

#or_else_get(supplier = nil, &block) ⇒ Object 



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# File 'lib/j8/optional.rb', line 86

def or_else_get(supplier = nil, &block)
  callable = from_callable_class(supplier, block, J8::Supplier)

  if present?
    @value
  else
    callable.get.tap do |result|
      raise J8::NilException if result.nil?
    end
  end
end

#or_else_raise(supplier = nil, &block) ⇒ Object 



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# File 'lib/j8/optional.rb', line 98

def or_else_raise(supplier = nil, &block)
  callable = from_callable_class(supplier, block, J8::Supplier)
  raise callable.get unless present?

  @value
end

#present? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/j8/optional.rb', line 67

def present?
  !@value.nil?
end