str.contains strict=False takes no effect

[sorhawell]

Polars version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of Polars.

Issue description

expr.str.contains has a strict argument which if False , should not raise error for invalid regex pattern however an error is raised always at query time in either case.

I think this is also a problem in rust as I see the same behavior in r-polars

Reproducible example

In [1]: import polars as pl

In [2]: pl.version()
Out[2]: '0.16.5'

In [3]: pl.select(pl.lit("some_text").str.contains("(invalid_pattern",literal=False,strict=False))
---------------------------------------------------------------------------
ComputeError                              Traceback (most recent call last)
Cell In[3], line 1
----> 1 pl.select(pl.lit("some_text").str.contains("(invalid_pattern",literal=False,strict=False))

File /usr/local/Cellar/ipython/8.8.0/libexec/lib/python3.11/site-packages/polars/internals/lazy_functions.py:2335, in select(exprs, *more_exprs, **named_exprs)
   2287 def select(
   2288     exprs: (
   2289         str
   (...)
   2297     **named_exprs: str | PolarsExprType | PythonLiteral | pli.Series | None,
   2298 ) -> pli.DataFrame:
   2299     """
   2300     Run polars expressions without a context.
   2301 
   (...)
   2333 
   2334     """
-> 2335     return pli.DataFrame().select(exprs, *more_exprs, **named_exprs)

File /usr/local/Cellar/ipython/8.8.0/libexec/lib/python3.11/site-packages/polars/internals/dataframe/frame.py:5784, in DataFrame.select(self, exprs, *more_exprs, **named_exprs)
   5666 def select(
   5667     self,
   5668     exprs: (
   (...)
   5677     **named_exprs: str | PolarsExprType | PythonLiteral | pli.Series | None,
   5678 ) -> Self:
   5679     """
   5680     Select columns from this DataFrame.
   5681 
   (...)
   5779 
   5780     """
   5781     return self._from_pydf(
   5782         self.lazy()
   5783         .select(exprs, *more_exprs, **named_exprs)
-> 5784         .collect(no_optimization=True)
   5785         ._df
   5786     )

File /usr/local/Cellar/ipython/8.8.0/libexec/lib/python3.11/site-packages/polars/internals/lazyframe/frame.py:1146, in LazyFrame.collect(self, type_coercion, predicate_pushdown, projection_pushdown, simplify_expression, no_optimization, slice_pushdown, common_subplan_elimination, streaming)
   1135     common_subplan_elimination = False
   1137 ldf = self._ldf.optimization_toggle(
   1138     type_coercion,
   1139     predicate_pushdown,
   (...)
   1144     streaming,
   1145 )
-> 1146 return pli.wrap_df(ldf.collect())

ComputeError: regex error: Syntax(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regex parse error:
    (invalid_pattern
    ^
error: unclosed group
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
)

In [4]: pl.select(pl.lit("some_text").str.contains("(invalid_pattern",literal=False,strict=True))
---------------------------------------------------------------------------
ComputeError                              Traceback (most recent call last)
Cell In[4], line 1
----> 1 pl.select(pl.lit("some_text").str.contains("(invalid_pattern",literal=False,strict=True))

File /usr/local/Cellar/ipython/8.8.0/libexec/lib/python3.11/site-packages/polars/internals/lazy_functions.py:2335, in select(exprs, *more_exprs, **named_exprs)
   2287 def select(
   2288     exprs: (
   2289         str
   (...)
   2297     **named_exprs: str | PolarsExprType | PythonLiteral | pli.Series | None,
   2298 ) -> pli.DataFrame:
   2299     """
   2300     Run polars expressions without a context.
   2301 
   (...)
   2333 
   2334     """
-> 2335     return pli.DataFrame().select(exprs, *more_exprs, **named_exprs)

File /usr/local/Cellar/ipython/8.8.0/libexec/lib/python3.11/site-packages/polars/internals/dataframe/frame.py:5784, in DataFrame.select(self, exprs, *more_exprs, **named_exprs)
   5666 def select(
   5667     self,
   5668     exprs: (
   (...)
   5677     **named_exprs: str | PolarsExprType | PythonLiteral | pli.Series | None,
   5678 ) -> Self:
   5679     """
   5680     Select columns from this DataFrame.
   5681 
   (...)
   5779 
   5780     """
   5781     return self._from_pydf(
   5782         self.lazy()
   5783         .select(exprs, *more_exprs, **named_exprs)
-> 5784         .collect(no_optimization=True)
   5785         ._df
   5786     )

File /usr/local/Cellar/ipython/8.8.0/libexec/lib/python3.11/site-packages/polars/internals/lazyframe/frame.py:1146, in LazyFrame.collect(self, type_coercion, predicate_pushdown, projection_pushdown, simplify_expression, no_optimization, slice_pushdown, common_subplan_elimination, streaming)
   1135     common_subplan_elimination = False
   1137 ldf = self._ldf.optimization_toggle(
   1138     type_coercion,
   1139     predicate_pushdown,
   (...)
   1144     streaming,
   1145 )
-> 1146 return pli.wrap_df(ldf.collect())

ComputeError: regex error: Syntax(
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
regex parse error:
    (invalid_pattern
    ^
error: unclosed group
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
)

Expected behavior

when strict= False contains should return Null for invalid regex patterns

Installed versions

---Version info---
Polars: 0.16.5
Index type: UInt32
Platform: macOS-12.6.3-x86_64-i386-64bit
Python: 3.11.1 (main, Dec 23 2022, 09:40:27) [Clang 14.0.0 (clang-1400.0.29.202)]
---Optional dependencies---
pyarrow: <not installed>
pandas: <not installed>
numpy: <not installed>
fsspec: <not installed>
connectorx: <not installed>
xlsx2csv: <not installed>
deltalake: <not installed>
matplotlib: <not installed>

[ritchie46]

Thanks for the report. Could you make a PR?

[sorhawell]

I will give it a try