Skip to content

Commit

Permalink
[optional-chaining] Refactor optional chaining helper functions
Browse files Browse the repository at this point in the history 
Summary: This is a simple refactoring of the helper functions used by optional chaining. Some behavior has been factored out into separate functions, and will (in upcoming diffs) be called separately. We also thread through a little more info, which will be used for method chains.

Reviewed By: panagosg7

Differential Revision: D18302023

fbshipit-source-id: 08ba769e518999c0f399f259d40b488649743768
  • Loading branch information
@mvitousek @facebook-github-bot
mvitousek authored and facebook-github-bot committed Nov 5, 2019
1 parent 33cacfe commit 12c264e
Showing 1 changed file with 80 additions and 65 deletions.
145 changes: 80 additions & 65 deletions src/typing/statement.ml
View file
Original file line number Diff line number Diff line change
Expand Up @@ -4067,24 +4067,9 @@ and subscript ~is_cond cx ex =
Below are several helper functions for setting up this tuple in the
presence of chaining.
*)
let handle_chaining object_ ~get_result ~test_hooks ~get_opt_use ~get_reason =
match opt_state with
| NonOptional ->
(* Proceeding as normal: no need to worry about optionality, so T2 from
above is None. We're guaranteed that there are no optional chain
operators below this point in the chain, so we can call expression_
rather than recur_chain. *)
let (((_, obj_t), _) as object_ast) = expression cx object_ in
let reason = get_reason obj_t in
let lhs_t =
match test_hooks obj_t with
| Some hit -> hit
| None -> get_result reason obj_t
in
(lhs_t, None, lhs_t, object_ast)
| NewChain ->
let (chain_t, voided_t, object_ast) = recur_chain ~is_cond:false cx object_ in
(* We've encountered an optional chaining operator.
let handle_new_chain
lhs_reason (chain_t, voided_t, object_ast) ~get_reason ~test_hooks ~get_opt_use =
(* We've encountered an optional chaining operator.
We need to flow the "success" type of object_ into a OptionalChainT
type, which will "filter out" VoidT and NullT from the type of
object_ and flow them into `voided_out`, and then flow any non-void
Expand All @@ -4099,53 +4084,80 @@ and subscript ~is_cond cx ex =
the first place. We also take voided_t, equivalent to T2 above and
representing any previous chain short-circuits, and it will
contribute to the failure/short-circuit output of this function,
`voided_out`.
*)
let reason = get_reason chain_t in
let lhs_reason = mk_expression_reason object_ in
let chain_reason = mk_reason ROptionalChain loc in
let mem_t =
match test_hooks chain_t with
| Some hit -> hit
| None -> Tvar.mk cx reason
in
let voided_out = Tvar.mk cx reason in
Flow.flow
cx
( chain_t,
OptionalChainT
(chain_reason, lhs_reason, apply_opt_use (get_opt_use reason) mem_t, voided_out) );
Option.iter ~f:(fun voided_t -> Flow.flow_t cx (voided_t, voided_out)) voided_t;
`voided_out`. *)
let reason = get_reason chain_t in
let chain_reason = mk_reason ROptionalChain loc in
let mem_t =
match test_hooks chain_t with
| Some hit -> hit
| None -> Tvar.mk cx reason
in
let voided_out = Tvar.mk cx reason in
Flow.flow
cx
( chain_t,
OptionalChainT
(chain_reason, lhs_reason, apply_opt_use (get_opt_use reason) mem_t, voided_out) );
Option.iter ~f:(fun voided_t -> Flow.flow_t cx (voided_t, voided_out)) voided_t;
let lhs_t =
Tvar.mk_where cx reason (fun t ->
Flow.flow_t cx (mem_t, t);
Flow.flow_t cx (voided_out, t))
in
(mem_t, Some voided_out, lhs_t, object_ast)
in
let handle_continue_chain (chain_t, voided_t, object_ast) ~get_result ~test_hooks ~get_reason =
(* We're looking at a non-optional call or member access, but one where
deeper in the chain there was an optional chaining operator. We don't
need to do anything special locally, but we do need to remember that
we might have short-circuited before getting here--that's the
voided_t parameter. We'll flow that type into the type of the overall
expression to account for that possibility.
*)
let reason = get_reason chain_t in
let res_t =
match test_hooks chain_t with
| Some hit -> hit
| None -> get_result reason chain_t
in
let lhs_t =
match voided_t with
| Some voided_t ->
let lhs_tvar = Tvar.mk cx reason in
Flow.flow_t cx (res_t, lhs_tvar);
Flow.flow_t cx (voided_t, lhs_tvar);
lhs_tvar
| None -> res_t
in
(res_t, voided_t, lhs_t, object_ast)
in
let handle_chaining opt object_ ~get_result ~test_hooks ~get_opt_use ~get_reason =
match opt with
| NonOptional ->
(* Proceeding as normal: no need to worry about optionality, so T2 from
above is None. We don't need to consider optional short-circuiting, so
we can call expression_ rather than recur_chain. *)
let (((_, obj_t), _) as object_ast) = expression cx object_ in
let reason = get_reason obj_t in
let lhs_t =
Tvar.mk_where cx reason (fun t ->
Flow.flow_t cx (mem_t, t);
Flow.flow_t cx (voided_out, t))
in
(mem_t, Some voided_out, lhs_t, object_ast)
| ContinueChain ->
let (chain_t, voided_t, object_ast) = recur_chain ~is_cond cx object_ in
(* We're looking at a non-optional call or member access, but one where
deeper in the chain there was an optional chaining operator. We don't
need to do anything special locally, but we do need to remember that
we might have short-circuited before getting here--that's the
voided_t parameter. We'll flow that type into the type of the overall
expression to account for that possibility.
*)
let reason = get_reason chain_t in
let res_t =
match test_hooks chain_t with
match test_hooks obj_t with
| Some hit -> hit
| None -> get_result reason chain_t
in
let lhs_t =
Tvar.mk_where cx reason (fun t ->
Flow.flow_t cx (res_t, t);
Option.iter ~f:(fun voided_t -> Flow.flow_t cx (voided_t, t)) voided_t)
| None -> get_result reason obj_t
in
(res_t, voided_t, lhs_t, object_ast)
(lhs_t, None, lhs_t, object_ast)
| NewChain ->
let lhs_reason = mk_expression_reason object_ in
handle_new_chain
lhs_reason
(recur_chain ~is_cond:false cx object_)
~get_reason
~test_hooks
~get_opt_use
| ContinueChain ->
handle_continue_chain (recur_chain ~is_cond cx object_) ~get_result ~test_hooks ~get_reason
in
let maybe_refine () =
match opt_state with
let maybe_refine (loc, e) opt =
match opt with
| NonOptional -> Refinement.get cx (loc, e) loc
| _ -> None
in
Expand All @@ -4163,7 +4175,7 @@ and subscript ~is_cond cx ex =
let use_op = Op (GetProperty (mk_expression_reason ex)) in
let opt_use = OptGetElemT (use_op, reason, tind) in
let get_mem_t _ obj_t =
match maybe_refine () with
match maybe_refine (loc, e) opt_state with
| Some t -> t
| None ->
Tvar.mk_where cx reason (fun t ->
Expand All @@ -4173,6 +4185,7 @@ and subscript ~is_cond cx ex =
let test_hooks = Fn.const None in
let (filtered_out, voided_out, lhs_t, object_ast) =
handle_chaining
opt_state
_object
~get_result:get_mem_t
~test_hooks
Expand Down Expand Up @@ -4202,7 +4215,7 @@ and subscript ~is_cond cx ex =
None
in
let get_mem_t _ obj_t =
match maybe_refine () with
match maybe_refine (loc, e) opt_state with
| Some t -> t
| None ->
Tvar.mk_where cx expr_reason (fun t ->
Expand All @@ -4211,6 +4224,7 @@ and subscript ~is_cond cx ex =
in
let (filtered_out, voided_out, lhs_t, object_ast) =
handle_chaining
opt_state
_object
~get_result:get_mem_t
~test_hooks
Expand Down Expand Up @@ -4238,7 +4252,7 @@ and subscript ~is_cond cx ex =
None
in
let get_mem_t _ obj_t =
match maybe_refine () with
match maybe_refine (loc, e) opt_state with
| Some t -> t
| None ->
Tvar.mk_where cx expr_reason (fun t ->
Expand All @@ -4247,6 +4261,7 @@ and subscript ~is_cond cx ex =
in
let (filtered_out, voided_out, lhs_t, object_ast) =
handle_chaining
opt_state
_object
~get_result:get_mem_t
~test_hooks
Expand Down Expand Up @@ -4288,7 +4303,7 @@ and subscript ~is_cond cx ex =
in
let test_hooks = Fn.const None in
let (filtered_out, voided_out, lhs_t, object_ast) =
handle_chaining callee ~get_result ~test_hooks ~get_opt_use ~get_reason
handle_chaining opt_state callee ~get_result ~test_hooks ~get_opt_use ~get_reason
in
(filtered_out, voided_out, ((loc, lhs_t), exp object_ast))
| _ ->
Expand Down

0 comments on commit 12c264e

Please sign in to comment.