42 lines
1.3 KiB
Ruby
42 lines
1.3 KiB
Ruby
module Vm
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module IfStatement
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# an if evaluates the condition and jumps to the true block if true
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# so the else block is automatically after that.
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# But then the else needs to jump over the true block unconditionally.
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def on_IfStatement( statement )
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# branch_type , condition , if_true , if_false = *statement
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true_block = compile_if_condition( statement )
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merge = compile_if_false( statement )
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add_code true_block
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compile_if_true(statement)
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add_code merge
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nil # statements don't return anything
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end
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private
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def compile_if_condition( statement )
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reset_regs
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process(statement.condition)
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branch_class = Object.const_get "Register::Is#{statement.branch_type.capitalize}"
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true_block = Register.label(statement, "if_true")
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add_code branch_class.new( statement.condition , true_block )
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return true_block
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end
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def compile_if_true( statement )
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reset_regs
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process(statement.if_true)
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end
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def compile_if_false( statement )
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reset_regs
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process(statement.if_false) if statement.if_false.statements
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merge = Register.label(statement , "if_merge")
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add_code Register::Branch.new(statement.if_false, merge )
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merge
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end
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end
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end
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