Fix for #1430 #1591
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Fix for #1430 #1591
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added 2 commits
September 11, 2014 02:03
To test, use: > scripted tests/set-every
The implementation of Relation should in theory make no difference whether an element is unmapped, or whether it is mapped to an empty set. One of the changes in 322f6de introduced an optimization to the '+' operation on Relations that, in theory, should have made no difference to the semantic. The result of that optimization is that some mappings of the form "elem -> Set()" are no longer inserted in the forwardMap of the Relation. Unfortunately, the change resulted in the breakage of sbt#1430, causing "set every" to behave incorrectly. There must be, somewhere in the code, a test on the presence of a key rather than an access via <relation>.get(), or some other access that bypasses the supposed semantic equivalence described above. I spent several hours trying to track down exactly the offending test, without success. By undoing the relevant change in 322f6de, "set every" works again. That however offers no guarantee that everything else will keep working correctly; the underlying quirk in the code that depends on this supposedly inessential detail is also still lurking in the code, which is less than ideal.
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Hmm, look like this breaks the logic unit tests, so it appears we have something relying on the NEW behavior too. I'll investigate. |
The optimization, and therefore the change in the behavior of Relation, is now needed by the class Logic, and cannot be reverted. This patch (written by Josh) therefore changes the implementation of setAll() so that _1s is no longer used.
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LGTM, after travis is green we can merge! |
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In Relation,
_1sis defined as "Returns the set of all_1s such that(_1, _2)is in this relation.". Which is false: it is implemented as fwd.keySet, but it should be fwd.filterNot(_._2.isEmpty).keySet. Except setAll() depends on the incorrect semantics, and the apparently innocuous optimization in 322f6de broke it as a result. This pull request reverts the change, pending an implementation of setAll which does not depend on_1s(after which_1scan probably be fixed). See #1430.