Class: CodeNthCdrInstruction
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_nth_cdr.rb', line 27
def cleanup
pushes :code, @result
end
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#derive ⇒ Object
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# File 'lib/instructions/code/code_nth_cdr.rb', line 10
def derive
tree = NudgeProgram.new(@arg2)
raise InstructionMethodError,
"#{self.class.to_nudgecode} cannot parse the argument" unless tree.parses?
backbone = tree.linked_code
if backbone.kind_of?(CodeblockPoint)
b_len = backbone.contents.length
if b_len > 0
new_tree = CodeblockPoint.new(backbone.contents.slice(@arg1 % b_len, b_len))
else
new_tree = CodeblockPoint.new([])
end
else
new_tree = @arg1 > 0 ? CodeblockPoint.new([tree.linked_code]) : CodeblockPoint.new([])
end
@result = ValuePoint.new("code", new_tree.blueprint)
end
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#preconditions? ⇒ Boolean
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# File 'lib/instructions/code/code_nth_cdr.rb', line 2
def preconditions?
needs :int, 1
needs :code, 1
end
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#setup ⇒ Object
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# File 'lib/instructions/code/code_nth_cdr.rb', line 6
def setup
@arg1 = @context.pop_value(:int)
@arg2 = @context.pop_value(:code)
end
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