Add Zipper.search_pattern/2

[zachallaun]

Expanding on #147 which introduced Zipper.move_to_cursor/2, this PR adds a more general Zipper.search_pattern/2, which can match an arbitrarily nested pattern.

Also included is a small fix that makes do_find private (it was accidentally exposed) and a refactor for move_to_cursor.

cc @zachdaniel, @NickNeck

[NickNeck]

I am not sure if I understand everything right, maybe I overlook something. But a pattern with __cursor__() returns the same result for move_to_cursor/2 and search_to_pattern/2 for the same zipper. So the generalisation of search_to_pattern/2 is that it doesn't needs a __cursor__(). If I am right with that assumption, I would suggest to rename search_to_pattern/2 in move_to_pattern/2 and ignore __cursor__() in this function. Then we have both functionalities with a clear name.

[zachallaun]

So the generalisation of search_to_pattern/2 is that it doesn't needs a cursor().

Not quite; the generalization is that search_to_pattern/2 is that the pattern doesn't have to match at the top level, while move_to_cursor/2 does:

iex(1)> code = """
...(1)> if :foo != :bar do
...(1)>   IO.puts("hello")
...(1)> end
...(1)> """ |> Sourceror.parse_string!() |> Sourceror.Zipper.zip()

iex(2)> pattern = "IO.puts(__cursor__())"
"IO.puts(__cursor__())"

iex(3)> Sourceror.Zipper.move_to_cursor(code, pattern)
nil

iex(4)> Sourceror.Zipper.search_to_pattern(code, pattern)
#Sourceror.Zipper<
  #...
  {:__block__, [trailing_comments: [], leading_comments: [], delimiter: "\"", line: 2, column: 11],
   ["hello"]}
>

Now that I'm thinking about it, though, maybe find_pattern/2 might be a better name?

[NickNeck]

@zachallaun thanks for your explanation. My assumption about how move_to_cursor works was wrong. Now everything is clear and looks great. I think find_pattern/2 would be a better name.

[doorgan]

This looks great!
On the naming part, I think search_pattern is a good name, find_* suggest to me that it will find with a function(like find, find_value, find_index etc in Enum), on the flip side I haven't seen many functions in the wild using search_* which makes me less worried about naming inconsistencies

[zachallaun]

Renamed search_to_pattern -> search_pattern 🙂

[doorgan]

Awesome, thank you!