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Clean up string processing: delimiters #7852

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09b9fb6
Clean up string processing
cknitt Sep 6, 2025
7379d01
CHANGELOG
cknitt Sep 7, 2025
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Expand Up @@ -37,6 +37,7 @@

- Playground: Add config options for experimental features and jsx preserve mode. https://github.com/rescript-lang/rescript/pull/7865
- Clean up tests. https://github.com/rescript-lang/rescript/pull/7861 https://github.com/rescript-lang/rescript/pull/7871
- Clean up string processing (delimiters). https://github.com/rescript-lang/rescript/pull/7852

# 12.0.0-beta.10

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4 changes: 2 additions & 2 deletions compiler/core/j.ml
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Expand Up @@ -75,7 +75,7 @@ and for_ident = ident
and for_direction = Js_op.direction_flag
and property_map = (property_name * expression) list
and length_object = Js_op.length_object
and delim = External_arg_spec.delim = DNone | DStarJ | DNoQuotes | DBackQuotes
and string_kind = String_kind.t = Standard | Verbatim | RawJs | Template
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The current naming (DStarJ and such) is pretty bad, but I'm not a big fan of Standard and Verbatim, Verbatim is a double quoted string right? First time I hear about verbatim for strings but might be more common in other languages. But what about standard, what does it mean?

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I'll revisit this next week. Maybe I'll split the PR into two to separate the renaming from the other changes, and maybe we want to choose different names.


and expression_desc =
| Length of expression * length_object
Expand Down Expand Up @@ -139,7 +139,7 @@ and expression_desc =
async: bool;
directive: string option;
}
| Str of {delim: delim; txt: string}
| Str of {kind: string_kind; txt: string}
(* A string is UTF-8 encoded, and may contain
escape sequences.
*)
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4 changes: 2 additions & 2 deletions compiler/core/js_analyzer.ml
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Expand Up @@ -201,9 +201,9 @@ let rec eq_expression ({expression_desc = x0} : J.expression)
| Bin (op1, a1, b1) ->
op0 = op1 && eq_expression a0 a1 && eq_expression b0 b1
| _ -> false)
| Str {delim = a0; txt = b0} -> (
| Str {kind = a0; txt = b0} -> (
match y0 with
| Str {delim = a1; txt = b1} -> a0 = a1 && b0 = b1
| Str {kind = a1; txt = b1} -> a0 = a1 && b0 = b1
| _ -> false)
| Static_index (e0, p0, off0) -> (
match y0 with
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12 changes: 6 additions & 6 deletions compiler/core/js_dump.ml
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Expand Up @@ -720,16 +720,16 @@ and expression_desc cxt ~(level : int) f x : cxt =
P.string f L.code_point_at;
(* FIXME: use code_point_at *)
P.paren_group f 1 (fun _ -> expression ~level:0 cxt f b))
| Str {delim; txt} ->
| Str {kind; txt} ->
(*TODO --
when utf8-> it will not escape '\\' which is definitely not we want
*)
let () =
match delim with
| DStarJ -> P.string f ("\"" ^ txt ^ "\"")
| DNoQuotes -> P.string f txt
| DNone -> Js_dump_string.pp_string f txt
| DBackQuotes -> P.string f ("`" ^ txt ^ "`")
match kind with
| Verbatim -> P.string f ("\"" ^ txt ^ "\"")
| RawJs -> P.string f txt
| Standard -> Js_dump_string.pp_string f txt
| Template -> P.string f ("`" ^ txt ^ "`")
in
cxt
| Raw_js_code {code = s; code_info = info} -> (
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53 changes: 27 additions & 26 deletions compiler/core/js_exp_make.ml
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Expand Up @@ -156,8 +156,8 @@ let pure_runtime_call module_name fn_name args =

let runtime_ref module_name fn_name = runtime_var_dot module_name fn_name

let str ?(delim = J.DNone) ?comment txt : t =
{expression_desc = Str {txt; delim}; comment}
let str ?(kind = J.Standard) ?comment txt : t =
{expression_desc = Str {txt; kind}; comment}

let raw_js_code ?comment info s : t =
{
Expand Down Expand Up @@ -209,7 +209,7 @@ let instanceof ?comment (e0 : t) (e1 : t) : t =
{expression_desc = Bin (InstanceOf, e0, e1); comment}

let is_array (e0 : t) : t =
let f = str "Array.isArray" ~delim:DNoQuotes in
let f = str "Array.isArray" ~kind:RawJs in
{expression_desc = Call (f, [e0], Js_call_info.ml_full_call); comment = None}

let new_ ?comment e0 args : t = {expression_desc = New (e0, Some args); comment}
Expand Down Expand Up @@ -548,7 +548,8 @@ let array_length ?comment (e : t) : t =

let string_length ?comment (e : t) : t =
match e.expression_desc with
| Str {txt; delim = DNone} -> int ?comment (Int32.of_int (String.length txt))
| Str {txt; kind = Standard} ->
int ?comment (Int32.of_int (String.length txt))
(* No optimization for {j||j}*)
| _ -> {expression_desc = Length (e, String); comment}

Expand All @@ -566,31 +567,31 @@ let function_length ?comment (e : t) : t =
*)

let rec string_append ?comment (e : t) (el : t) : t =
let concat a b ~delim = {e with expression_desc = Str {txt = a ^ b; delim}} in
let concat a b ~kind = {e with expression_desc = Str {txt = a ^ b; kind}} in
match (e.expression_desc, el.expression_desc) with
| Str {txt = ""}, _ -> el
| _, Str {txt = ""} -> e
| ( Str {txt = a; delim},
String_append ({expression_desc = Str {txt = b; delim = delim_}}, c) )
when delim = delim_ ->
string_append ?comment (concat a b ~delim) c
| ( String_append (c, {expression_desc = Str {txt = b; delim}}),
Str {txt = a; delim = delim_} )
when delim = delim_ ->
string_append ?comment c (concat b a ~delim)
| ( String_append (a, {expression_desc = Str {txt = b; delim}}),
String_append ({expression_desc = Str {txt = c; delim = delim_}}, d) )
when delim = delim_ ->
string_append ?comment (string_append a (concat b c ~delim)) d
| Str {txt = a; delim}, Str {txt = b; delim = delim_} when delim = delim_ ->
{(concat a b ~delim) with comment}
| ( Str {txt = a; kind},
String_append ({expression_desc = Str {txt = b; kind = kind_}}, c) )
when kind = kind_ ->
string_append ?comment (concat a b ~kind) c
| ( String_append (c, {expression_desc = Str {txt = b; kind}}),
Str {txt = a; kind = kind_} )
when kind = kind_ ->
string_append ?comment c (concat b a ~kind)
| ( String_append (a, {expression_desc = Str {txt = b; kind}}),
String_append ({expression_desc = Str {txt = c; kind = kind_}}, d) )
when kind = kind_ ->
string_append ?comment (string_append a (concat b c ~kind)) d
| Str {txt = a; kind}, Str {txt = b; kind = kind_} when kind = kind_ ->
{(concat a b ~kind) with comment}
| _, _ -> {comment; expression_desc = String_append (e, el)}

let obj ?comment ?dup properties : t =
{expression_desc = Object (dup, properties); comment}

let str_equal (txt0 : string) (delim0 : External_arg_spec.delim) txt1 delim1 =
if delim0 = delim1 then
let str_equal (txt0 : string) (kind0 : String_kind.t) txt1 kind1 =
if kind0 = kind1 then
if Ext_string.equal txt0 txt1 then Some true
else if
Ast_utf8_string.simple_comparison txt0
Expand Down Expand Up @@ -1242,7 +1243,7 @@ let rec float_equal ?comment (e0 : t) (e1 : t) : t =
let int_equal = float_equal

let tag_type = function
| Ast_untagged_variants.String s -> str s ~delim:DStarJ
| Ast_untagged_variants.String s -> str s ~kind:Verbatim
| Int i -> small_int i
| Float f -> float f
| BigInt i ->
Expand All @@ -1258,7 +1259,7 @@ let tag_type = function
| Untagged FunctionType -> str "function"
| Untagged StringType -> str "string"
| Untagged (InstanceType i) ->
str (Ast_untagged_variants.Instance.to_string i) ~delim:DNoQuotes
str (Ast_untagged_variants.Instance.to_string i) ~kind:RawJs
| Untagged ObjectType -> str "object"
| Untagged UnknownType ->
(* TODO: this should not happen *)
Expand All @@ -1280,7 +1281,7 @@ let rec emit_check (check : t Ast_untagged_variants.DynamicChecks.t) =
| IsInstanceOf (Array, x) -> is_array (emit_check x)
| IsInstanceOf (instance, x) ->
let instance_name = Ast_untagged_variants.Instance.to_string instance in
instanceof (emit_check x) (str instance_name ~delim:DNoQuotes)
instanceof (emit_check x) (str instance_name ~kind:RawJs)
| Not x -> not (emit_check x)
| Expr x -> x

Expand Down Expand Up @@ -1343,8 +1344,8 @@ let to_int32 ?comment (e : J.expression) : J.expression =

let string_comp (cmp : Lam_compat.comparison) ?comment (e0 : t) (e1 : t) =
match (e0.expression_desc, e1.expression_desc) with
| Str {txt = a0; delim = d0}, Str {txt = a1; delim = d1} -> (
match (cmp, str_equal a0 d0 a1 d1) with
| Str {txt = a0; kind = k0}, Str {txt = a1; kind = k1} -> (
match (cmp, str_equal a0 k0 a1 k1) with
| Ceq, Some b -> bool b
| Cneq, Some b -> bool (b = false)
| _ -> bin ?comment (Lam_compile_util.jsop_of_comp cmp) e0 e1)
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2 changes: 1 addition & 1 deletion compiler/core/js_exp_make.mli
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Expand Up @@ -95,7 +95,7 @@ val pure_runtime_call :

val runtime_ref : string -> string -> t

val str : ?delim:J.delim -> ?comment:string -> string -> t
val str : ?kind:J.string_kind -> ?comment:string -> string -> t

val ocaml_fun :
?comment:string ->
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12 changes: 6 additions & 6 deletions compiler/core/lam.ml
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Expand Up @@ -430,7 +430,7 @@ let switch lam (lam_switch : lambda_switch) : t =

let stringswitch (lam : t) cases default : t =
match lam with
| Lconst (Const_string {s; delim = None | Some DNoQuotes}) ->
| Lconst (Const_string {s; kind = RawJs}) ->
Ext_list.assoc_by_string cases s default
| _ -> Lstringswitch (lam, cases, default)

Expand Down Expand Up @@ -471,7 +471,7 @@ module Lift = struct

let bool b = if b then true_ else false_

let string s : t = Lconst (Const_string {s; delim = None})
let string s : t = Lconst (Const_string {s; kind = Standard})

let char b : t = Lconst (Const_char b)
end
Expand All @@ -488,7 +488,7 @@ let prim ~primitive:(prim : Lam_primitive.t) ~args loc : t =
Lift.int (Int32.of_float (float_of_string a))
(* | Pnegfloat -> Lift.float (-. a) *)
(* | Pabsfloat -> Lift.float (abs_float a) *)
| Pstringlength, Const_string {s; delim = None} ->
| Pstringlength, Const_string {s; kind = Standard} ->
Lift.int (Int32.of_int (String.length s))
(* | Pnegbint Pnativeint, ( (Const_nativeint i)) *)
(* -> *)
Expand Down Expand Up @@ -537,11 +537,11 @@ let prim ~primitive:(prim : Lam_primitive.t) ~args loc : t =
| Psequor, Const_js_false, Const_js_true -> true_
| Psequor, Const_js_false, Const_js_false -> false_
| ( Pstringadd,
Const_string {s = a; delim = None},
Const_string {s = b; delim = None} ) ->
Const_string {s = a; kind = Standard},
Const_string {s = b; kind = Standard} ) ->
Lift.string (a ^ b)
| ( (Pstringrefs | Pstringrefu),
Const_string {s = a; delim = None},
Const_string {s = a; kind = Standard},
Const_int {i = b} ) -> (
try Lift.char (Char.code (String.get a (Int32.to_int b)))
with _ -> default ())
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6 changes: 3 additions & 3 deletions compiler/core/lam_compile_const.ml
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Expand Up @@ -61,8 +61,8 @@ and translate (x : Lam_constant.t) : J.expression =
| Const_char i -> Js_of_lam_string.const_char i
| Const_bigint (sign, i) -> E.bigint sign i
| Const_float f -> E.float f (* TODO: preserve float *)
| Const_string {s; delim = None | Some DNoQuotes} -> E.str s
| Const_string {s; delim = Some delim} -> E.str ~delim s
| Const_string {s; kind = RawJs} -> E.str s
| Const_string {s; kind} -> E.str ~kind s
| Const_pointer name -> E.str name
| Const_block (tag, tag_info, xs) ->
Js_of_lam_block.make_block NA tag_info (E.small_int tag)
Expand All @@ -79,4 +79,4 @@ and translate (x : Lam_constant.t) : J.expression =
let translate_arg_cst (cst : External_arg_spec.cst) =
match cst with
| Arg_int_lit i -> E.int (Int32.of_int i)
| Arg_string_lit (s, delim) -> E.str s ~delim
| Arg_string_lit (s, kind) -> E.str s ~kind
8 changes: 4 additions & 4 deletions compiler/core/lam_constant_convert.ml
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Expand Up @@ -27,8 +27,8 @@ let rec convert_constant (const : Lambda.structured_constant) : Lam_constant.t =
| Const_base (Const_int i) -> Const_int {i = Int32.of_int i; comment = None}
| Const_base (Const_char i) -> Const_char i
| Const_base (Const_string (s, opt)) ->
let delim = Ast_utf8_string_interp.parse_processed_delim opt in
Const_string {s; delim}
let kind = Ast_utf8_string_interp.parse_processed_delim opt in
Const_string {s; kind = Option.value ~default:Standard kind}
| Const_base (Const_float i) -> Const_float i
| Const_base (Const_int32 i) -> Const_int {i; comment = None}
| Const_base (Const_int64 _) -> assert false
Expand Down Expand Up @@ -59,7 +59,7 @@ let rec convert_constant (const : Lambda.structured_constant) : Lam_constant.t =
if Ext_string.is_valid_hash_number name then
Const_int {i = Ext_string.hash_number_as_i32_exn name; comment = None}
else Const_pointer name)
| Const_immstring s -> Const_string {s; delim = None}
| Const_immstring s -> Const_string {s; kind = Standard}
| Const_block (t, xs) -> (
let tag = Lambda.tag_of_tag_info t in
match t with
Expand All @@ -76,7 +76,7 @@ let rec convert_constant (const : Lambda.structured_constant) : Lam_constant.t =
let tag_val : Lam_constant.t =
if Ext_string.is_valid_hash_number s then
Const_int {i = Ext_string.hash_number_as_i32_exn s; comment = None}
else Const_string {s; delim = None}
else Const_string {s; kind = Standard}
in
Const_block (tag, t, [tag_val; convert_constant value])
| _ -> assert false))
4 changes: 2 additions & 2 deletions compiler/core/lam_convert.ml
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Expand Up @@ -184,7 +184,7 @@ let lam_prim ~primitive:(p : Lambda.primitive) ~args loc : Lam.t =
let tag_val : Lam_constant.t =
if Ext_string.is_valid_hash_number s then
Const_int {i = Ext_string.hash_number_as_i32_exn s; comment = None}
else Const_string {s; delim = None}
else Const_string {s; kind = Standard}
in
prim
~primitive:(Pmakeblock (tag, info, mutable_flag))
Expand Down Expand Up @@ -465,7 +465,7 @@ let convert (exports : Set_ident.t) (lam : Lambda.lambda) :
| Lprim (Pgetglobal id, args, _) ->
let args = Ext_list.map args convert_aux in
if Ident.is_predef_exn id then
Lam.const (Const_string {s = id.name; delim = None})
Lam.const (Const_string {s = id.name; kind = Standard})
else (
may_depend may_depends (Lam_module_ident.of_ml ~dynamic_import id);
assert (args = []);
Expand Down
13 changes: 7 additions & 6 deletions compiler/core/lam_pass_lets_dce.ml
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Expand Up @@ -63,7 +63,7 @@ let lets_helper (count_var : Ident.t -> Lam_pass_count.used_info) lam : Lam.t =
->
Hash_ident.add subst v (simplif l1);
simplif l2
| _, Lconst (Const_string {s; delim = None}) ->
| _, Lconst (Const_string {s; kind = Standard}) ->
(* only "" added for later inlining *)
Hash_ident.add string_table v s;
Lam.let_ Alias v l1 (simplif l2)
Expand Down Expand Up @@ -112,7 +112,7 @@ let lets_helper (count_var : Ident.t -> Lam_pass_count.used_info) lam : Lam.t =
| _ -> (
let l1 = simplif l1 in
match l1 with
| Lconst (Const_string {s; delim = None}) ->
| Lconst (Const_string {s; kind = Standard}) ->
Hash_ident.add string_table v s;
(* we need move [simplif lbody] later, since adding Hash does have side effect *)
Lam.let_ Alias v l1 (simplif lbody)
Expand All @@ -127,7 +127,7 @@ let lets_helper (count_var : Ident.t -> Lam_pass_count.used_info) lam : Lam.t =
let l1 = simplif l1 in

match (kind, l1) with
| Strict, Lconst (Const_string {s; delim = None}) ->
| Strict, Lconst (Const_string {s; kind = Standard}) ->
Hash_ident.add string_table v s;
Lam.let_ Alias v l1 (simplif l2)
| _ -> Lam_util.refine_let ~kind v l1 (simplif l2))
Expand Down Expand Up @@ -157,7 +157,7 @@ let lets_helper (count_var : Ident.t -> Lam_pass_count.used_info) lam : Lam.t =
let r' = simplif r in
let opt_l =
match l' with
| Lconst (Const_string {s = ls; delim = None}) -> Some ls
| Lconst (Const_string {s = ls; kind = Standard}) -> Some ls
| Lvar i -> Hash_ident.find_opt string_table i
| _ -> None
in
Expand All @@ -166,13 +166,14 @@ let lets_helper (count_var : Ident.t -> Lam_pass_count.used_info) lam : Lam.t =
| Some l_s -> (
let opt_r =
match r' with
| Lconst (Const_string {s = rs; delim = None}) -> Some rs
| Lconst (Const_string {s = rs; kind = Standard}) -> Some rs
| Lvar i -> Hash_ident.find_opt string_table i
| _ -> None
in
match opt_r with
| None -> Lam.prim ~primitive:Pstringadd ~args:[l'; r'] loc
| Some r_s -> Lam.const (Const_string {s = l_s ^ r_s; delim = None})))
| Some r_s -> Lam.const (Const_string {s = l_s ^ r_s; kind = Standard}))
)
| Lglobal_module _ -> lam
| Lprim {primitive; args; loc} ->
Lam.prim ~primitive ~args:(Ext_list.map args simplif) loc
Expand Down
10 changes: 5 additions & 5 deletions compiler/frontend/ast_attributes.ml
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Expand Up @@ -220,7 +220,7 @@ let iter_process_bs_int_as (attrs : t) =
| _ -> ());
!st

type as_const_payload = Int of int | Str of string * External_arg_spec.delim
type as_const_payload = Int of int | Str of string * String_kind.t

let iter_process_bs_string_or_int_as (attrs : Parsetree.attributes) =
let st = ref None in
Expand Down Expand Up @@ -248,13 +248,13 @@ let iter_process_bs_string_or_int_as (attrs : Parsetree.attributes) =
]
when Ast_utf8_string_interp.parse_processed_delim delim_ <> None
-> (
let delim =
let kind =
match Ast_utf8_string_interp.parse_processed_delim delim_ with
| None -> assert false
| Some delim -> delim
| Some kind -> kind
in
st := Some (Str (s, delim));
if delim = DNoQuotes then
st := Some (Str (s, kind));
if kind = RawJs then
(* check that it is a valid object literal *)
match
Classify_function.classify
Expand Down
2 changes: 1 addition & 1 deletion compiler/frontend/ast_attributes.mli
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Expand Up @@ -50,7 +50,7 @@ val has_unwrap_attr : t -> bool

val iter_process_bs_int_as : t -> int option

type as_const_payload = Int of int | Str of string * External_arg_spec.delim
type as_const_payload = Int of int | Str of string * String_kind.t
val iter_process_bs_string_or_int_as : t -> as_const_payload option

val process_derive_type : t -> derive_attr * t
Expand Down
2 changes: 1 addition & 1 deletion compiler/frontend/ast_external_process.ml
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Expand Up @@ -89,7 +89,7 @@ let refine_arg_type ~(nolabel : bool) (ptyp : Ast_core_type.t) :
| Int i ->
(* This type is used in obj only to construct obj type*)
Arg_cst (External_arg_spec.cst_int i)
| Str (i, delim) -> Arg_cst (External_arg_spec.cst_string i delim))
| Str (i, kind) -> Arg_cst (External_arg_spec.cst_string i kind))
else (* ([`a|`b] [@string]) *)
spec_of_ptyp nolabel ptyp

Expand Down
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