Compilation #1
Compilation #1
Conversation
which tests are you talking about? If I run |
Multimodcrafter
force-pushed
the
compilation
branch
from
7a13bbd to
3de6167
Compare
We require two vm instructions 'CheckLookaround' and 'WriteLookaround' to be able to track the state of lookaround expressions at the current position in the haystack. Both instructions access a new 'lookaround' vector of booleans, which contains one entry per lookaround expression in the regex.
These changes implement the compilation of lookaround assertions from HIR to NFA. Subexpressions of lookaround assertions are patched to a top level reverse union. This is necessary so that the NFA will explore the innermost subexpression first and thereby make sure that all subexpression results are available when they need to be checked. I.e. any `WriteLookaround` state must be visited before any `CheckLookaround` state with the same index.
The machinery necessary to perform the parallel lookbehind checking should only be compiled in when there is actually a lookbehind expression in the regex. This restores compilation to the expected outputs for regexes without lookbehind expressions.
This makes it so we don't need to reset the lookaround state on each character advancement.
Multimodcrafter
force-pushed
the
compilation
branch
from
5b80341 to
2413c2e
Compare
| /// look-around sub-expression with the given index evaluates to `positive` | ||
| /// at the current position in the haystack. |
There was a problem hiding this comment.
That is outdated now that we use indices
There was a problem hiding this comment.
Not really, we are using indices to track the state of look-arounds but the semantics of the CheckLookAround instruction is still to provide a conditional epsilon transition on the predicate as described. That is, the transition will be taken if the look-around sub-expression evaluates to positive at the current position, but the way this is checked is no longer via direct boolean comparison but rather by first evaluating last_true_pos == current_pos and only then compare the result to positive.
There was a problem hiding this comment.
I was referring to the point about how this check is now done. But indeed the docs do not have to be this precise about it here
Rename certain enums to be consistent with rest of codebase.
No description provided.