BestFirstSearch: don't give up too soon #1729
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@olafurpg the change is simple enough but likely requires your level of understanding of the existing algorithm to review, PTAL. @tanishiking @poslegm fyi. |
olafurpg
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Feb 21, 2020
scalafmt-core/shared/src/main/scala/org/scalafmt/internal/BestFirstSearch.scala
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Currently, the algorithm would clear the search priority queue when the top candidate points to a new statement. Sometimes this leads to losing a viable path and the dreaded "Unable to format due to bug" error. Rather than clearing the queue, let's maintain several generations of priority queues and create a new generation on a new statement, thus continuing to process subsequent states just like the old algorithm did but with the previously discarded states available as backup. Apply this modification to top-level invocations only, so that nested calls will still terminate early; thus the backup candidates are really processed at the very end of the existing logic. Fixes scalameta#448. Fixes scalameta#1462. Fixes scalameta#1485. Fixes scalameta#1599. Fixes scalameta#1717.
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Currently, the algorithm would clear the search priority queue when the top candidate points to a new statement. Sometimes this leads to losing a viable path and the dreaded "Unable to format due to bug" error.
Rather than clearing the queue, let's maintain several generations of priority queues and create a new generation on a new statement, thus continuing to process subsequent states just like the old algorithm did but with the previously discarded states available as backup.
Apply this modification to top-level invocations only, so that nested calls will still terminate early; thus the backup candidates are really processed at the very end of the existing logic.
Fixes #448. Fixes #1462. Fixes #1485. Fixes #1599. Fixes #1717.
NB:
scala-reposdiffs, looks like they contain files previously unformatted byscalafmt: kitbellew/scala-repos@0876f01?w=1