Class: CodeConsInstruction

Inherits:
Instruction show all
Defined in:
lib/instructions/code/code_cons.rb

Overview

This is a tricky one to translate from Push, which assumes a very Lisp-like list structure. Here we’ll simply build a new block with the consed item first, and the original code second.

Instance Attribute Summary

Attributes inherited from Instruction

#context

Instance Method Summary collapse

Methods inherited from Instruction

all_instructions, #go, inherited, #initialize, #needs, #pushes, to_nudgecode

Constructor Details

This class inherits a constructor from Instruction

Instance Method Details

#cleanup ⇒ Object 



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# File 'lib/instructions/code/code_cons.rb', line 22

def cleanup
  pushes :code, @result
end

#derive ⇒ Object 



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# File 'lib/instructions/code/code_cons.rb', line 11

def derive
  t1 = NudgeProgram.new(@arg1)
  t2 = NudgeProgram.new(@arg2)
  if t1.parses? && t2.parses?
    consed_tree = t2.insert_point_before(1,t1.linked_code)
  else
    raise InstructionMethodError,
      "#{self.class.to_nudgecode} cannot parse the arguments"
  end
  @result = ValuePoint.new("code", consed_tree.blueprint)
end

#preconditions? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/instructions/code/code_cons.rb', line 4

def preconditions?
  needs :code, 2
end

#setup ⇒ Object 



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# File 'lib/instructions/code/code_cons.rb', line 7

def setup
  @arg2 = @context.pop_value(:code)
  @arg1 = @context.pop_value(:code)
end