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Using SableCC’s Visitor Pattern
The main way of using SableCC’s visitor pattern is to define a
class which extends DepthFirstAdapter.
By over-riding the methods inAAssignStm or
outAAssignStm etc. we can specify code to be executed
when entering or leaving each node during a depth first traversal
of the syntax tree.
If we want to modify the order of traversal then we can over-ride
caseAAssignStm etc. but this is often not necessary.
The in and out methods return void, but the class provides
HashTable in, out; which we can use to store types of
expressions.
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