Package net.emustudio.edigen.passes

Class MergePatternsVisitor

java.lang.Object

net.emustudio.edigen.Visitor

net.emustudio.edigen.passes.MergePatternsVisitor

public class MergePatternsVisitor
extends Visitor

A visitor which merges multiple patterns of a variant into one mask + pattern.

In addition, it sets starting offsets for subrules. Expectation of a tree at input:

   Rule
     Variant
       Subrule
       Subrule
       Constant
       ...
 

Expectation of the tree at output:

   Rule
     Variant
       Subrule
       Subrule
       Mask
       Pattern
 

Constructor Summary

Constructors

Constructor	Description
MergePatternsVisitor()

Method Summary

Modifier and Type	Method	Description
void	visit(Pattern pattern)	Appends "true" bits to the mask (because these bits will be checked during decoding) and itself to the pattern (these bits should be the result of masking during decoding).
void	visit(Subrule subrule)	Sets the starting offset of the subrule.
void	visit(Variant variant)	Traverses all children nodes and adds one mask and pattern as a result of joining.

Methods inherited from class net.emustudio.edigen.Visitor

visit, visit, visit, visit, visit, visit, visit, visit

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MergePatternsVisitor

public MergePatternsVisitor()

Method Detail

visit

public void visit(Variant variant)
           throws SemanticException

Traverses all children nodes and adds one mask and pattern as a result of joining.

Overrides:

visit in class Visitor

Parameters:

variant - the variant node

Throws:

SemanticException - never

visit

public void visit(Pattern pattern)

Appends "true" bits to the mask (because these bits will be checked during decoding) and itself to the pattern (these bits should be the result of masking during decoding).

Overrides:

visit in class Visitor

Parameters:

pattern - the pattern node

visit

public void visit(Subrule subrule)
           throws SemanticException

Sets the starting offset of the subrule.

If the subrule has length specified, adds "false" bits to the mask because these bits will not be checked against a pattern during decoding.

If the subrule does not refer to a rule (it is used only to return a value), it is removed from the tree.

Overrides:

visit in class Visitor

Parameters:

subrule - the subrule node

Throws:

SemanticException - when pre-pattern is longer than expected