Class: Skeem::SkmPair

Inherits:
SkmElement show all
Defined in:
lib/skeem/skm_pair.rb

Instance Attribute Summary collapse

Attributes inherited from SkmElement

#position

Class Method Summary collapse

Instance Method Summary collapse

Methods inherited from SkmElement

#boolean?, #bound!, #callable?, #char?, #complex?, #done!, #inspect, #integer?, #null?, #number?, #procedure?, #rational?, #real?, #skm_eq?, #string?, #symbol?, #vector?

Constructor Details

#initialize(head, tail) ⇒ SkmPair

Returns a new instance of SkmPair.



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# File 'lib/skeem/skm_pair.rb', line 16

def initialize(head, tail)
  super(0)
  @car = head
  @cdr = tail
end

Instance Attribute Details

#car ⇒ SkmElement Also known as: first

Returns:



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# File 'lib/skeem/skm_pair.rb', line 8

def car
  @car
end

#cdr ⇒ SkmElement

Returns:



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# File 'lib/skeem/skm_pair.rb', line 11

def cdr
  @cdr
end

Class Method Details

.create_from_a(anArray) ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 46

def self.create_from_a(anArray)
  current = nil
  return SkmEmptyList.instance if anArray.empty?

  anArray.reverse_each do |elem|
    if current.nil?
      current = new(elem, SkmEmptyList.instance)
    else
      current = new(elem, current)
    end
  end

  current
end

Instance Method Details

#accept(aVisitor) ⇒ Object

Part of the 'visitee' role in Visitor design pattern.

Parameters:



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# File 'lib/skeem/skm_pair.rb', line 189

def accept(aVisitor)
  aVisitor.visit_pair(self)
end

#append(anElement) ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 147

def append(anElement)
  last_one = last_pair
  if last_one.cdr.nil? || last_one.cdr.kind_of?(SkmEmptyList)
    last_one.cdr = SkmPair.new(anElement, SkmEmptyList.instance)
  else
    raise StandardError, "Cannot append #{anElement.inspect}"
  end
end

#append_list(aList) ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 156

def append_list(aList)
  last_one = last_pair
  if last_one.cdr.nil? || last_one.cdr.kind_of?(SkmEmptyList)
    last_one.cdr = aList
  else
    raise StandardError, "Cannot append list #{aList.inspect}"
  end
end

#clone_evaluate(aRuntime) ⇒ Object

Construct new instance with car and cdr respectively equal to car.evaluate and cdr.evaluate



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# File 'lib/skeem/skm_pair.rb', line 33

def clone_evaluate(aRuntime)
  new_car = car.evaluate(aRuntime)
  if cdr.nil?
    new_cdr = nil
  elsif cdr.kind_of?(SkmPair)
    new_cdr = cdr.clone_evaluate(aRuntime)
  else
    new_cdr = cdr.evaluate(aRuntime)
  end

  self.class.new(new_car, new_cdr)
end

#each(&aBlock) ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 142

def each(&aBlock)
  aBlock.call(car)
  cdr.each(&aBlock) if cdr && !cdr.null?
end

#empty? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skeem/skm_pair.rb', line 61

def empty?
  return false if car

  if [SkmPair, SkmEmptyList].include? cdr.class
    cdr.empty?
  else
    false
  end
end

#eqv?(_other) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skeem/skm_pair.rb', line 118

def eqv?(_other)
  false
end

#evaluate(aRuntime) ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 165

def evaluate(aRuntime)
  return SkmEmptyList.instance if empty?

  if car.kind_of?(SkmIdentifier) && car.is_var_name
    result = aRuntime.evaluate_form(self)
  else
    begin
      result = clone_evaluate(aRuntime)
    rescue NoMethodError => e
      $stderr.puts "SkmPair#evaluate:   #{inspect}"
      $stderr.puts "SkmPair as Array:   #{to_a.inspect}"
      raise e
    end
  end
  result
end

#klone ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 22

def klone
  if cdr.kind_of?(SkmPair)
    new_cdr = cdr.klone
  else
    new_cdr = cdr
  end
  self.class.new(car, new_cdr)
end

#last ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 114

def last
  to_a.last
end

#last_pair ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 101

def last_pair
  if cdr.nil? || (cdr == SkmEmptyList.instance) || !cdr.kind_of?(SkmPair)
    self
  else
    cdr.last_pair
  end
end

#length ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 83

def length
  if [SkmPair, SkmEmptyList].include?(cdr.class)
    cdr.length + 1
  else
    raise StandardError, 'Improper list'
  end
end

#list? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skeem/skm_pair.rb', line 71

def list?
  if cdr.nil?
    false
  else
    cdr.list?
  end
end

#members ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 14

alias members to_a

#pair? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skeem/skm_pair.rb', line 79

def pair?
  true
end

#proper? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skeem/skm_pair.rb', line 109

def proper?
  last_node = last_pair
  last_node.cdr.nil? || (last_node.cdr == SkmEmptyList.instance)
end

#quasiquote(aRuntime) ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 182

def quasiquote(aRuntime)
  members_eval = to_a.map { |elem| elem.quasiquote(aRuntime) }
  self.class.create_from_a(members_eval)
end

#quoted! ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 193

def quoted!
  car.quoted!
  cdr&.quoted!
end

#skm_equal?(other) ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skeem/skm_pair.rb', line 122

def skm_equal?(other)
  return true if equal?(other)

  equal = true
  if car.nil?
    equal = other.car.nil?
  else
    equal &&= car.skm_equal?(other.car)
  end
  return false unless equal

  if cdr.nil?
    equal &&= other.cdr.nil?
  else
    equal &&= cdr.skm_equal?(other.cdr)
  end

  equal
end

#to_a ⇒ Object

Works correctly for proper lists.



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# File 'lib/skeem/skm_pair.rb', line 92

def to_a
  result = [car]
  if cdr && !cdr.null?
    result.concat(cdr.to_a)
  end

  result
end

#unquoted! ⇒ Object 



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# File 'lib/skeem/skm_pair.rb', line 198

def unquoted!
  car.unquoted!
  cdr&.unquoted!
end

#verbatim? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/skeem/skm_pair.rb', line 203

def verbatim?
  return false unless car.verbatim?

  if cdr.nil?
    true
  else
    cdr.verbatim?
  end
end