dfs traversal: simplify edges in reverse mode#33481
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tgamblin merged 1 commit intospack:developfrom Oct 26, 2022
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In the dfs code, flip edges so that `parent` means `from` and `spec` means `to` in the direction of traversal. This makes it slightly easier to write generic/composable code. For example when using visitors where one visitor reverses direction, and another only cares about accepting particular edges or not depending on whether the target node is seen before, it would be good if the second visitor didn't have to know whether the order was changed or not.
tgamblin
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Oct 26, 2022
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LGTM -- this simplifies the traversal cases quite a bit. |
becker33
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Nov 2, 2022
In the dfs code, flip edges so that `parent` means `from` and `spec` means `to` in the direction of traversal. This makes it slightly easier to write generic/composable code. For example when using visitors where one visitor reverses direction, and another only cares about accepting particular edges or not depending on whether the target node is seen before, it would be good if the second visitor didn't have to know whether the order was changed or not.
charmoniumQ
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Nov 19, 2022
In the dfs code, flip edges so that `parent` means `from` and `spec` means `to` in the direction of traversal. This makes it slightly easier to write generic/composable code. For example when using visitors where one visitor reverses direction, and another only cares about accepting particular edges or not depending on whether the target node is seen before, it would be good if the second visitor didn't have to know whether the order was changed or not.
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In the dfs code, flip edges so that
parentalways meansfromandspecmeanstoin the direction of traversal. This makes it slightlyeasier to write generic/composable code. For example when using visitors
where one visitor reverses direction, and another only cares about
accepting particular edges or not depending on whether the
tonodeis seen before, it would be good if the second visitor didn't have to
know whether the order was changed or not.
As far as I can see, we never use
traverse_edges(direction="parents"), weonly ever use
traverse(direction="parents")which yields nodes not edges. Soshould be fine to flip those edges.
This change should help unify the code of #33406, since we can then
reuse
ReverseVisitor/CoverNodesVisitor/CoverEdgesVisitorinDFS and BFS.