feat: Added escape_regex operation to the str namespace and as a global function

[barak1412]

Fixes #19207.

[barak1412]

@orlp Just to be sure -

The code:

import polars as pl

df = pl.DataFrame({"text": ["abc", "def", None, "abc(\\w+)"]})

df.with_columns(escaped=pl.escape_regex('text'))

Should escape the 'text' literal, not the column, right?

Besides, I need to:

1. Add tests.
2. Add pl.escape_regex as function.
3. Refactor the code such that the namespace Expr will be translated to the function Expr.
4. Add to docs.

[orlp]

@barak1412 pl.escape_regex should only work on Python strings, and not interact with the expression API at all. I would suggest adding a warning/error if you try to pass in an expression into it, suggesting you to use Expr.str.escape_regex instead.

[codecov]

Codecov Report

Attention: Patch coverage is 47.36842% with 30 lines in your changes missing coverage. Please review.

Project coverage is 80.02%. Comparing base (d89fdcd) to head (27d460b).
Report is 23 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/polars-plan/src/dsl/string.rs	0.00%	8 Missing ⚠️
...rates/polars-plan/src/dsl/function_expr/strings.rs	0.00%	7 Missing ⚠️
...lars-ops/src/chunked_array/strings/escape_regex.rs	33.33%	6 Missing ⚠️
.../polars-ops/src/chunked_array/strings/namespace.rs	0.00%	4 Missing ⚠️
crates/polars-python/src/expr/string.rs	0.00%	3 Missing ⚠️
.../polars-python/src/lazyframe/visitor/expr_nodes.rs	0.00%	1 Missing ⚠️
py-polars/polars/expr/string.py	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #19257      +/-   ##
==========================================
- Coverage   80.04%   80.02%   -0.02%     
==========================================
  Files        1528     1531       +3     
  Lines      209564   209876     +312     
  Branches     2415     2421       +6     
==========================================
+ Hits       167741   167963     +222     
- Misses      41275    41362      +87     
- Partials      548      551       +3     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[barak1412]

Added this function so pl.escape_regex and str.escape_regex will be coupled by same implementation.

[barak1412]

@orlp I will be glad if you can look, thanks.

[orlp]

Can you add a dependency on regex_syntax (we already have this indirectly) in our main Cargo.toml, add a dependency with regex_syntax = { workspace = true } in the polars-ops Cargo.toml, and use a loop similar to this?

pub fn escape_regex(ca: &StringChunked) -> StringChunked {
    let mut buffer = String::new();
    let mut builder = StringChunkedBuilder::new(ca.name().clone(), ca.len());
    for opt_s in ca.iter() {
        if let Some(s) = opt_s {
            buffer.clear();
            regex_syntax::escape_into(s, &mut buffer);
            builder.append_value(&buffer);
        } else {
            builder.append_null();
        }
    }
}

This prevents us from having to allocate for each string.

[barak1412]

I had some Cargo.lock mess, will get to it tommorow evening.

[orlp]

Typo: Exp -> Expr.