Class: Relisp::Cons

Inherits:
Proxy show all
Defined in:
lib/relisp/type_conversion/programming_types.rb

Overview

A proxy to an Emacs cons. If the cons is actually a list, the to_list method will convert it a subclass of Array so that all of the ruby Array stuff is available.

Instance Attribute Summary

Attributes inherited from Proxy

#elisp_variable, #slave

Instance Method Summary collapse

Methods inherited from Proxy

elisp_alias, from_elisp, #makunbound, #to_elisp

Constructor Details

#initialize(*args) ⇒ Cons

args can be any of these forms:

  • (symbol, slave = Relisp.default_slave)

  • (_car, cdr, slave = Relisp.default_slave)

When a symbol is given it is considered to be the name of a pre-existing cons in the slave process. Otherwise a new cons is created with the given car and _cdr (cons).



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# File 'lib/relisp/type_conversion/programming_types.rb', line 155

def initialize(*args)
  super do |car, cdr|
    @slave.elisp_exec( "(setq #{@elisp_variable} (cons #{car.to_elisp} #{cdr.to_elisp}))")
  end
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Relisp::Proxy

Instance Method Details

#car=(newcar) ⇒ Object

Set the car of Cons to be newcar (setcar).



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# File 'lib/relisp/type_conversion/programming_types.rb', line 163

def car=(newcar)
  @slave.setcar(@elisp_variable.value, newcar)
end

#cdr=(newcdr) ⇒ Object

Set the cdr of Cons to be newcdr. (setcdr).



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# File 'lib/relisp/type_conversion/programming_types.rb', line 169

def cdr=(newcdr)
  @slave.setcdr(@elisp_variable.value, newcdr)
end

#list? ⇒ Boolean

This function will NOT return true whenever the elisp function listp is true. The elisp function is true whenever the object is a cons cell, but this method is true only when the cons can be unambiguously translated to an array; this condition is satisfied when the object in question could have been written using the elisp function list.

Returns:

  • (Boolean) 


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# File 'lib/relisp/type_conversion/programming_types.rb', line 193

def list?
  # current_cdr = cdr
  # while current_cdr.kind_of?(Cons)
  #   current_cdr = current_cdr.cdr
  # end
  # return ! current_cdr.nil?

  current_cdr_var = @slave.new_elisp_variable
  @slave.elisp_exec "(setq #{current_cdr_var} (cdr #{to_elisp}))"
  while @slave.elisp_eval "(consp #{current_cdr_var})"
    @slave.elisp_exec "(setq #{current_cdr_var} (cdr #{current_cdr_var}))"
  end
  cdr = @slave.elisp_eval "#{current_cdr_var}"
  @slave.elisp_exec "(makunbound '#{current_cdr_var})"

  return ! cdr
end

#to_list ⇒ Object Also known as: to_a

Translate the cons cell into a Relisp::List, a subclass of Array. See list? for when this can be done.



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# File 'lib/relisp/type_conversion/programming_types.rb', line 214

def to_list
  list_array = []

  # list_array << @slave.elisp_eval("(car #{to_elisp})")
  # current_cdr = @slave.elisp_eval("(cdr #{to_elisp})")
  # while current_cdr.kind_of?(Cons)
  #   list_array << @slave.elisp_eval("(car #{current_cdr.to_elisp})")
  #   current_cdr = @slave.elisp_eval("(cdr #{current_cdr.to_elisp})")
  # end

  # if current_cdr.nil?
  #   return Relisp::List.new(list_array)
  # else
  #   return false
  # end

  current_cdr_var = @slave.new_elisp_variable

  list_array << @slave.elisp_eval("(car #{to_elisp})")
  @slave.elisp_exec "(setq #{current_cdr_var} (cdr #{to_elisp}))"
  while @slave.elisp_eval "(consp #{current_cdr_var})"
    list_array << @slave.elisp_eval("(car #{current_cdr_var})")
    @slave.elisp_exec "(setq #{current_cdr_var} (cdr #{current_cdr_var}))"
  end

  cdr = @slave.elisp_eval "#{current_cdr_var}"

  @slave.elisp_exec "(makunbound '#{current_cdr_var})"

  if cdr
    raise "Not a list: #{cdr}"
  end

  return Relisp::List.new(list_array)
end