Add support for single-line regex anchors ^/$ in contains_re #9482
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davidwendt
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@@ Coverage Diff @@
## branch-21.12 #9482 +/- ##
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- Coverage 10.79% 10.66% -0.13%
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Files 116 117 +1
Lines 18869 19729 +860
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+ Hits 2036 2104 +68
- Misses 16833 17625 +792
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davidwendt
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3 - Ready for Review
ajschmidt8
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Oct 27, 2021
vyasr
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bdice
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Oct 29, 2021
bdice
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vyasr
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Nov 1, 2021
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@gpucibot merge |
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Closes #9439
The
^(begin anchor) and$(end anchor) apply to beginning of line (BOL) and end of line (EOL) respectively. This means that they cannot be used to match on strings containing embedded new-line ('\n') characters when desiring the anchors only match just the beginning and end of the string as a whole.Many regex engines support a flag for overriding the behavior of the BOL/EOL anchors: Python, Java, C++. This PR introduces a similar flag parameter to the
cudf::strings::contains_re,cudf::strings::matches_reandcudf::strings::count_reAPIs to tell the regex engine how to interpret the anchor characters in the given regex pattern.Additional information about these anchors can also be found here: https://www.regular-expressions.info/anchors.html
The current default behavior of the libcudf regex is to interpret BOL/EOL as similar to the
MULTILINEflag. This behavior doesn't match the engines/languages listed above. So for consistency the default is reversed requiring this PR to be a breaking change.Also, the new
flagsparameter added to the above APIs requires this to be a breaking change. An additional flag (DOTALL) is included in this PR since the internal regex code supports it but only needed a path for the caller to specify the behavior. TheDOTALLflag is also a feature of the above languages. When specified, the dot '.' pattern includes embedded new-line characters in its matching character set.