42 lines
1.6 KiB
Ruby
42 lines
1.6 KiB
Ruby
module Ast
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class IfExpression < Expression
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# attr_reader :cond, :if_true, :if_false
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def compile method , message
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# to execute the logic as the if states it, the blocks are the other way around
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# so we can the jump over the else if true ,and the else joins unconditionally after the true_block
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merge_block = method.new_block "if_merge" # last one, created first
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true_block = method.new_block "if_true" # second, linked in after current, before merge
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false_block = method.new_block "if_false" # directly next in order, ie if we don't jump we land here
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is = cond.compile(method,message)
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# TODO should/will use different branches for different conditions.
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# just a scetch : cond_val = cond_val.is_true?(method) unless cond_val.is_a? Virtual::BranchCondition
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method.add_code Virtual::ImplicitBranch.new( true_block )
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# compile the true block (as we think of it first, even it is second in sequential order)
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method.current true_block
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last = is
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if_true.each do |part|
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last = part.compile(method,message )
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raise part.inspect if last.nil?
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end
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# compile the false block
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method.current false_block
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if_false.each do |part|
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puts "compiling in if false #{part}"
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last = part.compile(method,message)
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raise part.inspect if last.nil?
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end
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method.add_code Virtual::UnconditionalBranch.new( merge_block )
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puts "compiled if: end"
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method.current merge_block
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#TODO should return the union of the true and false types
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last
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end
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end
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end |