This tries to simplify how a given sub-expression accepts the empty string. The goal is to modify the sub-expression
such that exactly one path accepts the empty string. This has the emergent result that the operator that causes the
sub-expression to accept the empty string moves closer to the root of the tree.
Examples:
a(?:b*|d?) => a(?:b+|d)?
||a*|b => (?:a+|b)?
This operation largely ignores the order of alternatives and usually reduces the ambiguity of the expression. If
order or ambiguity have to be preserved, then the effectiveness of this transformer will be greatly reduced.
This tries to simplify how a given sub-expression accepts the empty string. The goal is to modify the sub-expression such that exactly one path accepts the empty string. This has the emergent result that the operator that causes the sub-expression to accept the empty string moves closer to the root of the tree.
Examples:
a(?:b*|d?)=>a(?:b+|d)?||a*|b=>(?:a+|b)?This operation largely ignores the order of alternatives and usually reduces the ambiguity of the expression. If order or ambiguity have to be preserved, then the effectiveness of this transformer will be greatly reduced.