Stop the iteration of an exhausted, unknown-sized sequence when slicing #1324
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This PR fixes a bug with the slice operator that caused non value iterators of an unknown sized sequence to continue although the source sequence was exhausted, eventually accessing the value of a key/value pair that does not exist. The issue did not happen with fixed sized sequences since we can calculate resulting size in advance (as `sliceSize`) and bail out early. For an unknown sized sequence however, we can not know this size in advance (see this comment: [1]). To solve this, we now bail out when we encounter a completed iterator before proceeding to process it further. [1]: https://github.com/facebook/immutable-js/blob/27b231c8952366ddb96ab2a20d1eb351b3c8719e/src/Operations.js#L427-L428
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Great, thanks for adding a test! |
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Fixes #1256
This PR fixes a bug with the slice operator that caused non-value
iterators of an unknown sized sequence to continue although the source
sequence was exhausted, eventually accessing the value of a key/value
pair that does not exist.
The issue did not happen with fixed sized sequences since we can
calculate resulting size in advance (as
sliceSize) and bail out early.For an unknown sized sequence, however, we can not know this size in
advance (see this comment: 1).
To solve this, we now bail out when we encounter a completed iterator
before proceeding to process it further.