feat(parser): add parser module

1 files changed, 36 insertions, 0 deletions

diff --git a/2025/ocaml/lib/application/parser.ml b/2025/ocaml/lib/application/parser.ml
new file mode 100644
index 0000000..099900b
--- /dev/null
+++ b/2025/ocaml/lib/application/parser.ml
@@ -0,0 +1,36 @@
+(** [rows_of_string s] is a list of strings where each element is a row of [s]. *)
+let rows_of_string s =
+  s |> String.split_on_char '\n'
+  |> List.filter_map (fun l ->
+      let trimmed = String.trim l in
+      if trimmed <> "" then Some trimmed else None )
+
+(** [columns_of_string ?sep s] is a list of strings where each element is
+    a column of [s] where each column is separated by [sep]. *)
+let rec columns_of_string ?(sep = ' ') s =
+  rows_of_string s
+  |> List.map (fun l ->
+      l |> String.split_on_char sep |> List.filter (fun l -> l <> "") )
+  |> transpose
+
+(** [group_columns lst] is a list where the first element of each
+    sublist of [lst] is grouped in [acc] and so on for the rest of the elements.
+    Example: [group_columns [] \[\["abc"; "def"\]; \["ghi"; "jkl"\]\]] is the list [\[\["abc";"ghi"\];\["def";"jkl"\]\]]. *)
+and transpose lst =
+  assert (lst <> []) ;
+  if List.mem [] lst then []
+  else List.map List.hd lst :: transpose (List.map List.tl lst)
+
+let%expect_test "rows correctly parsed" =
+  let have = {| abc def
+    ghi jkl |} in
+  let rows = rows_of_string have in
+  List.iter (fun c -> print_string (c ^ " ")) rows ;
+  [%expect {| abc def ghi jkl |}]
+
+let%expect_test "columns correctly parsed" =
+  let have = {| abc def
+    ghi jkl |} in
+  let cols = columns_of_string have in
+  List.iter (fun row -> List.iter (fun c -> print_string (c ^ " ")) row) cols ;
+  [%expect {| abc ghi def jkl |}]