28 lines
853 B
Ruby
28 lines
853 B
Ruby
module Virtual
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module Compiler
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# while- attr_reader :condition, :body
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def self.compile_while expression, method
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start = Virtual::Label.new("while_start")
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method.add_code start
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is = expression.condition.compile(method )
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branch = Virtual::IsTrueBranch.new "while"
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merge = Virtual::Label.new(branch.name)
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branch.other = merge #false jumps to end of while
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method.add_code branch
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last = is
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expression.body.each do |part|
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last = part.compile(method )
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raise part.inspect if last.nil?
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end
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# unconditionally brnach to the start
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merge.next = method.current.next
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method.current.next = start
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# here we add the end of while that the branch jumps to
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#but don't link it in (not using add)
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method.current = merge
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last
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end
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end
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end
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