Semantic Analysis - Crafting a Compiler - page 351

class ThrowsVisitor extends NodeVisitor

procedure gather T hrows ( n )

9

call visit C hildren ( n )

ans ←∅
foreach c ∈ n . getChildren() do ans ← ans ∪ c . throwsSet
n . throwsSet ← ans

end

procedure visit ( IfTesting ifn )

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call gather T hrows ( ifn )

end

procedure visit (WhileLooping wn ) 11

call gather T hrows ( wn )

end

procedure visit (DoWhileLooping dwn )

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call gather T hrows ( dwn )

end

procedure visit (ForLooping fn )

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call gather T hrows ( fn )

end

procedure visit ( LabeledStmt ls )

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call gather T hrows ( ls )

end

procedure (Continuing cn )

cn . throwsSet ←∅

visit

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end

procedure (Breaking bn )

bn . throwsSet ←∅

visit

16

end

procedure visit (Returning rn )

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call gather T hrows ( rn )

end

procedure visit (Switching sn )

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call gather T hrows ( sn )

end

procedure visit (CaseItem cn )

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call gather T hrows ( cn )

end

procedure visit ( LabelList lln )

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/ Constant-valued expressions cannot throw exceptions /

lln . throwsSet ←∅

end

end

Figure 9.4: Throws Analysis Visitors (Part 1)