noop: extract Full_fidelity_parser.sub_of_pos

Summary: I wrote roughly the same function 3 times: might be a good time to factor it out, as suggested by ljw1004

Reviewed By: ljw1004

Differential Revision: D45912815

fbshipit-source-id: 866ac8555167d4707347890594665595cecb9b9f

hphp/hack/src/parser/full_fidelity_source_text.ml

@@ -120,3 +120,15 @@ let relative_pos pos_file source_text start_offset end_offset =
   let pos_start = offset_to_lnum_bol_offset start_offset in
   let pos_end = offset_to_lnum_bol_offset end_offset in
   Pos.make_from_lnum_bol_offset ~pos_file ~pos_start ~pos_end
+
+let sub_of_pos ?length source_text pos =
+  let offset =
+    let (first_line, first_col) = Pos.line_column pos in
+    position_to_offset source_text (first_line, first_col + 1)
+  in
+  let length =
+    match length with
+    | Some n -> n
+    | None -> Pos.length pos
+  in
+  sub source_text offset length

hphp/hack/src/parser/full_fidelity_source_text.mli

@@ -44,6 +44,9 @@ val line_text : t -> int -> string
 (** get a substring start at the ith char and continuing for length *)
 val sub : t -> int -> int -> string
 
+(** get a substring corresponding to a position. [length] defaults to the length of the position. *)
+val sub_of_pos : ?length:int -> t -> Pos.t -> string
+
 (** convert an absolute offset into a (line number, column) pair *)
 val offset_to_position : t -> int -> int * int
 

hphp/hack/src/server/codeActionsServiceExtractVariable.ml

@@ -17,15 +17,6 @@ type candidate = {
   placeholder_n: int;
 }
 
-let source_slice ~source_text ~start_pos ~length =
-  let offset =
-    let (first_line, first_col) = Pos.line_column start_pos in
-    Full_fidelity_source_text.position_to_offset
-      source_text
-      (first_line, first_col + 1)
-  in
-  Full_fidelity_source_text.sub source_text offset length
-
 (**
 We don't want to extract variables for lambdas like this: `() ==> 200`.
 The AST of such a lambda is indistinguishable from `() ==> { return 200; }`
@@ -35,7 +26,7 @@ let might_be_expression_lambda ~f_body:Aast.{ fb_ast } ~pos ~source_text =
   | [(stmt_pos, _)] ->
     let length = Pos.start_offset stmt_pos - Pos.start_offset pos in
     if length > 0 then
-      let src = source_slice ~source_text ~start_pos:pos ~length in
+      let src = Full_fidelity_source_text.sub_of_pos source_text pos ~length in
       not @@ String.is_substring ~substring:"{" src
     else
       (*  length can be negative to curlies in default params: `(($a = () ==> {}) ==> ...` *)
@@ -158,9 +149,7 @@ let top_visitor (selection : Pos.t) ~source_text =
 let command_or_action_of_candidate
     ~source_text ~path { stmt_pos; pos; placeholder_n } =
   let placeholder = Format.sprintf "%s%d" placeholder_base placeholder_n in
-  let exp_string =
-    source_slice ~source_text ~start_pos:pos ~length:(Pos.length pos)
-  in
+  let exp_string = Full_fidelity_source_text.sub_of_pos source_text pos in
   let change_expression =
     Lsp.TextEdit.
       {

hphp/hack/src/server/codeActionsServiceFlipAroundComma.ml

@@ -51,15 +51,6 @@ end = struct
       { insertion_index; positions; pos }
 end
 
-let source_slice ~source_text pos =
-  let offset =
-    let (first_line, first_col) = Pos.line_column pos in
-    Full_fidelity_source_text.position_to_offset
-      source_text
-      (first_line, first_col + 1)
-  in
-  Full_fidelity_source_text.sub source_text offset (Pos.length pos)
-
 let list_flip ~insertion_index l =
   let rec aux i = function
     | h1 :: h2 :: tail when i = insertion_index - 1 -> h2 :: h1 :: tail
@@ -198,7 +189,7 @@ let edit_of_candidate
     ~path ~source_text Candidate.{ insertion_index; positions; pos } =
   let text =
     positions
-    |> List.map ~f:(source_slice ~source_text)
+    |> List.map ~f:(Full_fidelity_source_text.sub_of_pos source_text)
     |> list_flip ~insertion_index
     |> String.concat ~sep:", "
   in

hphp/hack/src/server/codeActionsServiceInlineVariable.ml

@@ -26,15 +26,6 @@ type candidate = {
   use_pos: Pos.t;
 }
 
-let source_slice ~source_text pos =
-  let offset =
-    let (first_line, first_col) = Pos.line_column pos in
-    Full_fidelity_source_text.position_to_offset
-      source_text
-      (first_line, first_col + 1)
-  in
-  Full_fidelity_source_text.sub source_text offset (Pos.length pos)
-
 let remove_leading_whitespace ~source_text pos : Pos.t =
   let rec calc_strip_amount offset =
     let ch = Full_fidelity_source_text.get source_text offset in
@@ -280,7 +271,9 @@ let command_or_action_of_candidate ~path ~source_text { name; def; use_pos } =
     Lsp.{ TextEdit.range; newText = "" }
   in
   let change_replace_use =
-    let text = source_slice ~source_text def.def_rhs_pos in
+    let text =
+      Full_fidelity_source_text.sub_of_pos source_text def.def_rhs_pos
+    in
     let text =
       if def.def_needs_grouping then
         Printf.sprintf "(%s)" text