Add check for regex instructions causing an infinite-loop

[davidwendt]

Closes #10006

Fixes a use case where the regex pattern creates a set of instructions that can cause the regex evaluation process to go into an infinite loop. For example, the pattern (x?)+ creates the following instructions:

Instructions:
  0:    CHAR c='x', next=2
  1:      OR right=0, left=2, next=2
  2:    RBRA id=1, next=4
  3:    LBRA id=1, next=1
  4:      OR right=3, left=5, next=5
  5:     END
startinst_id=3
startinst_ids: [ 3 -1]

This causes in an infinite loop at instruction 4 where the path may go like: 4->3->1->2->4 ... forever.
Supporting this pattern does not look possible. The + quantifier is applied to capture group symbol ) inside of which x? means 0 or more repeating the character x. This means it could match x or nothing and so applying the + to nothing would be invalid. That said, the pattern x?+ currently already throws an error because of the invalid usage of + quantifier.

Therefore, the fix here adds a checking step after the instruction set is created to check for a possible infinite-loop case. If one is detected, an exception is thrown indicating the pattern is not supported.

[codecov]

Codecov Report

Merging #10095 (9fc3469) into branch-22.04 (e24fa8f) will increase coverage by 0.00%.
The diff coverage is 2.95%.

❗ Current head 9fc3469 differs from pull request most recent head 36bf19f. Consider uploading reports for the commit 36bf19f to get more accurate results

@@              Coverage Diff              @@
##           branch-22.04   #10095   +/-   ##
=============================================
  Coverage         10.37%   10.38%           
=============================================
  Files               119      119           
  Lines             20149    20220   +71     
=============================================
+ Hits               2091     2099    +8     
- Misses            18058    18121   +63     

Impacted Files	Coverage Δ
python/cudf/cudf/__init__.py	0.00% <ø> (ø)
python/cudf/cudf/_fuzz_testing/io.py	0.00% <0.00%> (ø)
python/cudf/cudf/_fuzz_testing/orc.py	0.00% <ø> (ø)
python/cudf/cudf/_fuzz_testing/parquet.py	0.00% <ø> (ø)
python/cudf/cudf/_fuzz_testing/utils.py	0.00% <0.00%> (ø)
python/cudf/cudf/api/types.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/_base_index.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/column/__init__.py	0.00% <ø> (ø)
python/cudf/cudf/core/column/column.py	0.00% <0.00%> (ø)
python/cudf/cudf/core/column/decimal.py	0.00% <0.00%> (ø)
... and 23 more

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[vyasr]

A couple questions (only one really important one) otherwise this looks good.

[vyasr]

LGTM

[davidwendt]

@gpucibot merge