Document retrieving capture group names from Regex or RegexMatch

[anandijain]

The Regex docs provide indexing with Symbol, where the symbol is the name of the capture group.

What is lacking is a way to retrieve the capture group names from either a Match or just the Regex itself (from the docs).

s = "aaa bbb ccc"
r = r"(?<a>.*) (?<b>.*) (?<c>.*)"
m = match(r, s) # I don't think there is a way to retrieve the symbols [:a, :b, :c] from this or `r`

One has to know about Base.PCRE.capture_names(m.regex.regex).

The context in which this arose was wanting to easily construct a DataFrame from a Vector{RegexMatch} where the capture group names become the column names. Thanks to @pdeffebach for finding the capture_names function for me.

This should be a simple PR to add a line to https://docs.julialang.org/en/v1/manual/strings/#Regular-Expressions mentioning it.

I may get to it, I may not xd

[BenjaminGalliot]

Related to #37299?

From the master branch, we now have a keys function.

s = "aaa bbb ccc"
r = r"(?<a>.*) (?<b>.*) (?<c>.*)"
m = match(r, s)
d = Dict(keys(m) .=> m)
# Dict{String, SubString{String}} with 3 entries:  "c" => "ccc"  "b" => "bbb"  "a" => "aaa"

[anandijain]

beautiful, indeed this is a duplicate. i will leave it open for documenting keys, as that PR just updated NEWS.md

[regier21]

I was looking into doing this and I noticed that none of the RegexMatch functions (or RegexMatch itself) are documented. Should I go ahead and add documentation for all of these?