dfa: fix bug in how the reverse DFA is called #970
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
In turns out that in *some* calls to Fsm::reverse, we were passing an incorrect start offset. Namely, the haystack we pass is sub-sliced at `&text[start..]`, but in some places, we were passing `text.len()` as the start offset of the reverse search. But of course, it should be `text.len() - start`. This was indeed the case in most places, but it looks like it needed to be corrected in two additional places. I've also added this test to regex-automata's set of regression tests and can confirm that it doesn't happen there. (regex-automata is far more principled about handling offsets like this.) Fixes #969
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
In turns out that in some calls to Fsm::reverse, we were passing an incorrect start offset. Namely, the haystack we pass is sub-sliced at
&text[start..], but in some places, we were passingtext.len()as the start offset of the reverse search. But of course, it should betext.len() - start. This was indeed the case in most places, but it looks like it needed to be corrected in two additional places.I've also added this test to regex-automata's set of regression tests and can confirm that it doesn't happen there. (regex-automata is far more principled about handling offsets like this.)
Fixes #969