Marko A. Rodriguez created TINKERPOP3-966:
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Summary: Support reversible traversals in MatchStep (and
respective MatchAlgorithms)
Key: TINKERPOP3-966
URL: https://issues.apache.org/jira/browse/TINKERPOP3-966
Project: TinkerPop 3
Issue Type: Improvement
Components: process
Affects Versions: 3.1.0-incubating
Reporter: Marko A. Rodriguez
Assignee: Marko A. Rodriguez
We currently do not support the reversing of a traversal. Thus,
{code}
g.V().match(
as("a").out("knows").as("b")
as("c").out("knows").as("a"))
{code}
will throw an exception saying that it can't compute the patterns. If we can
convert {{as("c").out("knows").as("a")}} to {{as("a").in("knows").as("c")}}
then this will work. Furthermore, we need a way to have two versions of a
traversal pattern available. For instance:
{code}
g.V().match(
as("a").out("knows").as("b")
as("a").out("friend").as("b"))
{code}
Given the above patterns, it is possible for both patterns to have a standard
and a "reversed-form" that can be selected dynamically given the
match-path-history and pattern statistics. Thus, we need a way to have all four
patterns able to be selected but once one of the two-pair is selected for a
traverser, it can't use the other.
In short, we need {{TraversalHelper.reverse(Traversal)}} and
{{MathStep.MatchAlgorithm}} book-keeping data structures.
cc/ [~mbroecheler]
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