Class: Calvin::Evaluator

Inherits:
Parslet::Transform
  • Object
show all
Defined in:
lib/calvin/evaluator.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Evaluator

Returns a new instance of Evaluator.



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# File 'lib/calvin/evaluator.rb', line 5

def initialize
  super
  @env = {}

  rule assignment: { identifier: simple(:name), expression:
    subtree(:expression)} do |context|
    @env[context[:name].to_s] = context[:expression]
  end

  rule deassignment: { identifier: simple(:name) } do |context|
    @env[context[:name].to_s]
  end

  rule range: subtree(:range) do
    if range[:first]
      range[:first]..range[:last]
    else
      0..(range[:last] - 1)
    end
  end

  rule folded: { binary_operator: simple(:op), folder: simple(:folder),
    expression: subtree(:expression) } do
    if folder == "\\"
    elsif folder == "\\:"
      expression.reverse!
    else
      raise Core::ImpossibleException
    end

    case op.to_sym
    when :+, :-, :%, :*, :/
      expression.reduce op.to_sym
    when :^
      expression.reduce :**
    else
      raise Core::ImpossibleException
    end
  end

  rule mapped: { monad: { left: { binary_operator: simple(:op) },
    integer: simple(:integer) }, mapper: simple(:mapper), expression: subtree(:expression) } do
    if mapper == "@"
    else
      raise Core::ImpossibleException
    end

    op = op().to_sym # hack; make it a var
    if op == :^
      op = :**
    end

    if expression.is_a?(Array) || expression.is_a?(Range)
      expression.to_a.map {|el| el.send(op, integer.to_i) }
    else
      expression.send(op, integer.to_i)
    end
  end

  rule mapped: { monad: { right: { binary_operator: simple(:op) },
    integer: simple(:integer) }, mapper: simple(:mapper), expression: subtree(:expression) } do
    if mapper == "@"
    else
      raise Core::ImpossibleException
    end

    op = op().to_sym # hack; make it a var
    if op == :^
      op = :**
    end

    if expression.is_a?(Array) || expression.is_a?(Range)
      expression.to_a.map {|el| integer.to_i.send(op, el) }
    else
      integer.to_i.send(op, expression)
    end
  end

  rule expression: subtree(:expression) do
    expression
  end

  rule mapped: { monad: { left: { comparison_operator: simple(:op) },
    integer: simple(:integer) }, mapper: simple(:mapper), expression: subtree(:expression) } do
    if mapper == "@"
    else
      raise Core::ImpossibleException
    end

    op = op().to_sym # hack; make it a var
    if op == :"<>"
      op = :!=
    elsif op == :"="
      op = :"=="
    end

    if expression.is_a?(Array) || expression.is_a?(Range)
      expression.to_a.select {|el| el.send(op, integer.to_i) }
    else
      expression.send(op, integer.to_i)
    end
  end

  rule mapped: { monad: { right: { comparison_operator: simple(:op) },
    integer: simple(:integer) }, mapper: simple(:mapper), expression: subtree(:expression) } do
    if mapper == "@"
    else
      raise Core::ImpossibleException
    end

    op = op().to_sym # hack; make it a var
    if op == :"<>"
      op = :!=
    elsif op == :"="
      op = :"=="
    end

    if expression.is_a?(Array) || expression.is_a?(Range)
      expression.to_a.select {|el| integer.to_i.send(op, el) }
    else
      expression.send(op, integer.to_i)
    end
  end
end

Instance Attribute Details

#env ⇒ Object

Returns the value of attribute env.



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# File 'lib/calvin/evaluator.rb', line 3

def env
  @env
end