perf(compiler): mark struct values with a string property

compiler/typescript-emitter.go

@@ -648,8 +648,7 @@ func renderPositionalStructConstructor(b *strings.Builder, structType *loweredSt
 
 	// Every instance carries the marker, false for a pointer's struct, so
 	// that all instances of a class have one shape.
-	b.WriteString("\t\t;(this as any)[" + runtimeOwner.QualifiedHelper(RuntimeHelperStructValueMarker))
-	b.WriteString("] = __goscriptValue === true\n\t}\n\n")
+	b.WriteString("\t\t;(this as any).__goStructValue = __goscriptValue === true\n\t}\n\n")
 }
 
 // renderPositionalStructClone emits the clone method of a positional struct
@@ -709,7 +708,6 @@ const structFreshInitParam = "__goscriptFresh"
 // renderStruct emits field storage, value-copy operations, methods, and metadata.
 func renderStruct(b *strings.Builder, structType *loweredStruct, runtimeOwner *RuntimeContractOwner, trimTypeInfo bool) {
 	markStructValue := runtimeOwner.QualifiedHelper(RuntimeHelperMarkAsStructValue)
-	structValueMarker := runtimeOwner.QualifiedHelper(RuntimeHelperStructValueMarker)
 	cloneStructValue := runtimeOwner.QualifiedHelper(RuntimeHelperCloneStructValue)
 	cloneArrayValue := runtimeOwner.QualifiedHelper(RuntimeHelperCloneArrayValue)
 	copyElement := runtimeOwner.QualifiedHelper(RuntimeHelperCopyElement)
@@ -833,9 +831,7 @@ func renderStruct(b *strings.Builder, structType *loweredStruct, runtimeOwner *R
 	// that each class stores it at one site. Every instance has the
 	// property, false for a pointer's struct, so that all instances of a
 	// class have one shape and marking one later changes no shape.
-	b.WriteString("\t\t;(this as any)[")
-	b.WriteString(structValueMarker)
-	b.WriteString("] = __goscriptValue === true\n\t}\n\n")
+	b.WriteString("\t\t;(this as any).__goStructValue = __goscriptValue === true\n\t}\n\n")
 
 	// The clone method copies the struct through its constructor.
 	b.WriteString("\tpublic ")

gs/builtin/builtin.ts

@@ -10,6 +10,7 @@ import type { Slice, SliceProxy, StringHeaderData } from './slice.js'
 import {
   arrayValueTypeInfo,
   cloneArrayValue,
+  ownKeys,
   isArrayValue,
   isMarkedAsStructValue,
   isTypeInfoComparable,
@@ -581,8 +582,8 @@ function fieldsEqual(
   a: Record<string, unknown>,
   b: Record<string, unknown>,
 ): boolean {
-  const aKeys = Object.keys(a)
-  const bKeys = Object.keys(b)
+  const aKeys = ownKeys(a)
+  const bKeys = ownKeys(b)
   if (aKeys.length !== bKeys.length) {
     return false
   }

gs/builtin/map.ts

@@ -3,6 +3,7 @@ import {
   canonicalPointerIdentity,
   isStructObject,
   isStructTypeInfo,
+  ownKeys,
   resolveTypeInfo,
   structFieldRuntimeKey,
   structValueMarker,
@@ -394,7 +395,7 @@ function structKeyPlan(key: object): StructKeyField[] {
 
   // The fields are sorted by name so equal keys give equal text.
   const kinds = structFieldKinds(key)
-  const plan = Object.keys(key)
+  const plan = ownKeys(key)
     .sort()
     .map((name) => ({ name, kind: kinds?.get(name) }))
 

gs/builtin/print.ts

@@ -1,5 +1,5 @@
 import { asArray, isSliceProxy, type Slice } from './slice.js'
-import { isStructObject } from './type.js'
+import { isStructObject, ownKeys } from './type.js'
 import { isVarRef } from './varRef.js'
 
 // A transpiled Go Error(), String(), or GoString() method may be async, so
@@ -210,7 +210,7 @@ function formatObject(
 function getObjectEntries(value: Record<string, any>): [string, any][] {
   // The fields of a struct are its own properties, functions included.
   if (isStructObject(value)) {
-    return Object.entries(value)
+    return ownKeys(value).map((key) => [key, value[key]])
   }
 
   return Object.entries(value).filter(

gs/builtin/type.ts

@@ -1055,7 +1055,7 @@ function matchesStructType(value: any, info: TypeInfo): boolean {
   if (typeof value === 'object' && value !== null && info.fields) {
     const fields = info.fields || []
     const fieldNames = fields.map((field) => structFieldRuntimeKey(field))
-    const valueFields = Object.keys(value)
+    const valueFields = ownKeys(value)
 
     const fieldsExist = fieldNames.every((field) => field in value)
     const sameFieldCount = valueFields.length === fieldNames.length
@@ -1440,8 +1440,22 @@ function typedElementMatches(
 
 // structValueMarker is the property that marks a struct instance as a value,
 // not a pointer. The constructors of generated struct classes set it
-// themselves.
-export const structValueMarker = Symbol('structValue')
+// themselves, by this name. It is a string key, which JavaScriptCore stores
+// as fast as a field, where a symbol key on a new object made every struct
+// value about ten times slower to make; ownKeys leaves it out of the keys of
+// an object.
+export const structValueMarker = '__goStructValue'
+
+// ownKeys returns the own enumerable keys of value, as Object.keys does,
+// without the struct value marker.
+export function ownKeys(value: object): string[] {
+  const keys = Object.keys(value)
+  const i = keys.lastIndexOf(structValueMarker)
+  if (i >= 0) {
+    keys.splice(i, 1)
+  }
+  return keys
+}
 
 // markAsStructValue Mark a struct instance as representing a value (not pointer).
 export function markAsStructValue<T>(value: T): T {
@@ -1737,7 +1751,7 @@ function forwardStructFields(view: object, read: () => unknown): void {
   if (typeof current !== 'object' || current === null) {
     return
   }
-  for (const key of Object.keys(current)) {
+  for (const key of ownKeys(current)) {
     Object.defineProperty(view, key, {
       configurable: true,
       enumerable: true,

gs/encoding/json/index.ts

@@ -738,7 +738,8 @@ function encodeJSON(v: unknown): string {
   }
   if (t === 'object') {
     const parts: string[] = []
-    for (const [key, value] of Object.entries(v as Record<string, unknown>)) {
+    for (const key of $.ownKeys(v as object)) {
+      const value = (v as Record<string, unknown>)[key]
       parts.push(JSON.stringify(key) + ':' + encodeJSON(value))
     }
     return '{' + parts.join(',') + '}'
@@ -2920,7 +2921,7 @@ function structFields(value: Record<string, unknown>): fieldMetadata[] {
   if (fields.length !== 0) {
     return fields
   }
-  return Object.keys(value).map((key) => ({ key, name: key }))
+  return $.ownKeys(value).map((key) => ({ key, name: key }))
 }
 
 // anonymousStructValueFields returns the fields of an anonymous struct

gs/fmt/fmt.ts

@@ -629,7 +629,7 @@ function defaultFormatMaybe(
       const fields: $.StructFieldInfo[] =
         info?.kind === $.TypeKind.Struct ?
           info.fields
-        : Object.keys(value).map((name) => ({
+        : $.ownKeys(value).map((name) => ({
             name,
             key: name,
             type: $.basicType('unknown'),
@@ -685,15 +685,15 @@ function defaultFormatMaybe(
       (value as any).constructor?.name &&
       (value as any).constructor.name !== 'Object'
     ) {
-      const parts = Object.entries(value as Record<string, any>).map(
-        ([k, v]) => {
+      const parts = $.ownKeys(value)
+        .map((key) => [key, value[key]] as const)
+        .map(([k, v]) => {
           const formatted = defaultFormatMaybe(v, flags, depth + 1)
           if (isPromiseLike(formatted)) {
             return formatted.then((resolved) => `${k}:${resolved}`)
           }
           return `${k}:${formatted}`
-        },
-      )
+        })
       return joinMaybe(parts, ' ', '{', '}')
     }
     try {

gs/hash/maphash/index.ts

@@ -267,7 +267,7 @@ function writeValue(h: Hash, v: unknown): void {
   const fields = $.isStructObject(v) ? v : undefined
   if ($.isMarkedAsStructValue(v) && fields) {
     h.WriteByte(7)
-    for (const key of Object.keys(fields)) {
+    for (const key of $.ownKeys(fields)) {
       writeValue(h, fields[key])
     }
     return

gs/reflect/deepequal.ts

@@ -49,7 +49,12 @@
 // values that have been compared before, it treats the values as
 // equal rather than examining the values to which they point.
 // This ensures that DeepEqual terminates.
-import { isNamedValueBox, isStructObject, isVarRef } from '../builtin/index.js'
+import {
+  isNamedValueBox,
+  isStructObject,
+  isVarRef,
+  ownKeys,
+} from '../builtin/index.js'
 import { ReflectValue } from './types.js'
 
 export function DeepEqual(
@@ -163,8 +168,8 @@ export function DeepEqual(
       return false
     }
 
-    const keysX = Object.keys(x)
-    const keysY = Object.keys(y)
+    const keysX = ownKeys(x)
+    const keysY = ownKeys(y)
     if (keysX.length !== keysY.length) {
       return false
     }

gs/reflect/type.ts

@@ -746,7 +746,7 @@ const invalidTypeInstance = new InvalidTypeClass()
 // without listing them all as Object.keys would.
 function isEmptyObject(value: object): boolean {
   for (const key in value) {
-    if (globalThis.Object.hasOwn(value, key)) {
+    if (key !== $.structValueMarker && globalThis.Object.hasOwn(value, key)) {
       return false
     }
   }

gs/unique/index.ts

@@ -105,7 +105,11 @@ function normalize(
   if ($.isStructObject(value)) {
     return {
       $type: value.constructor.name,
-      $fields: normalize({ ...value }, seen, nextID),
+      $fields: normalize(
+        Object.fromEntries($.ownKeys(value).map((k) => [k, value[k]])),
+        seen,
+        nextID,
+      ),
     }
   }
   const entries = Object.entries(value)

tests/tests/address_of_pointer_deref/address_of_pointer_deref.gs.ts

@@ -11,7 +11,7 @@ export class Col {
 	constructor(__goscriptValue?: boolean, Name$?: string, Default$?: $.VarRef<number> | null) {
 		this.Name = Name$ ?? ""
 		this.Default = Default$ ?? (null! as $.VarRef<number> | null)
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): Col {

tests/tests/address_taken_param_struct/address_taken_param_struct.gs.ts

@@ -11,7 +11,7 @@ export class Format {
 	constructor(__goscriptValue?: boolean, Name$?: string, Ext$?: $.Slice<string>) {
 		this.Name = Name$ ?? ""
 		this.Ext = Ext$ ?? (null! as $.Slice<string>)
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): Format {

tests/tests/addressed_struct_interface/addressed_struct_interface.gs.ts

@@ -18,7 +18,7 @@ export class Buffer {
 
 	constructor(__goscriptValue?: boolean, data$?: $.Slice<number>) {
 		this.data = data$ ?? (null! as $.Slice<number>)
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): Buffer {

tests/tests/anonymous_struct_field_address/anonymous_struct_field_address.gs.ts

@@ -8,7 +8,7 @@ export class entry {
 
 	constructor(__goscriptValue?: boolean, value$?: number) {
 		this.value = value$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): entry {
@@ -40,7 +40,7 @@ export class config {
 
 	constructor(__goscriptValue?: boolean, core$?: {"bare": boolean, "name": string}) {
 		this.core = core$ ?? $.anonymousStructValue({"bare": false, "name": ""}, { kind: $.TypeKind.Struct, methods: [], fields: [/* @__PURE__ */ $.structField("bare", /* @__PURE__ */ $.basicType("bool"), [0], 0, false, { pkgPath: "github.com/s4wave/goscript/tests/tests/anonymous_struct_field_address" }), /* @__PURE__ */ $.structField("name", /* @__PURE__ */ $.basicType("string"), [1], 8, false, { pkgPath: "github.com/s4wave/goscript/tests/tests/anonymous_struct_field_address" })] })
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): config {

tests/tests/anonymous_struct_slice/anonymous_struct_slice.gs.ts

@@ -11,7 +11,7 @@ export class namedItem {
 	constructor(__goscriptValue?: boolean, key$?: string, data$?: $.Slice<number>) {
 		this.key = key$ ?? ""
 		this.data = data$ ?? (null! as $.Slice<number>)
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): namedItem {

tests/tests/append_field_pointers/append_field_pointers.gs.ts

@@ -18,7 +18,7 @@ export class T {
 
 	constructor(__goscriptValue?: boolean, N$?: number) {
 		this.N = N$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): T {
@@ -58,7 +58,7 @@ export class Outer {
 	constructor(__goscriptValue?: boolean, T$?: T, X$?: number) {
 		this.T = T$ ?? new T(true)
 		this.X = X$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): Outer {
@@ -96,7 +96,7 @@ export class Pair {
 	constructor(__goscriptValue?: boolean, A$?: T, B$?: T) {
 		this.A = A$ ?? new T(true)
 		this.B = B$ ?? new T(true)
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): Pair {

tests/tests/append_spare_capacity/append_spare_capacity.gs.ts

@@ -11,7 +11,7 @@ export class pos {
 	constructor(__goscriptValue?: boolean, Line$?: number, Char$?: number) {
 		this.Line = Line$ ?? 0
 		this.Char = Char$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): pos {

tests/tests/append_value_copy/append_value_copy.gs.ts

@@ -9,7 +9,7 @@ export class cell {
 
 	constructor(__goscriptValue?: boolean, width$?: number) {
 		this.width = width$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): cell {

tests/tests/array_assign_in_place/array_assign_in_place.gs.ts

@@ -8,7 +8,7 @@ export class T {
 
 	constructor(__goscriptValue?: boolean, v$?: number) {
 		this.v = v$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): T {
@@ -42,7 +42,7 @@ export class S {
 	constructor(__goscriptValue?: boolean, A$?: T[], N$?: number[]) {
 		this.A = A$ ?? $.arrayValue(globalThis.Array.from({ length: 2 }, () => new T(true)), /* @__PURE__ */ $.arrayType("main.T", 2))
 		this.N = N$ ?? $.arrayValue(globalThis.Array.from({ length: 3 }, () => 0))
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): S {

tests/tests/array_byte_element_pointer/array_byte_element_pointer.gs.ts

@@ -8,7 +8,7 @@ export class bitset {
 
 	constructor(__goscriptValue?: boolean, bits$?: Uint8Array) {
 		this.bits = bits$ ?? $.arrayValue(new Uint8Array(4))
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): bitset {

tests/tests/array_index_variable/array_index_variable.gs.ts

@@ -11,7 +11,7 @@ export class point {
 	constructor(__goscriptValue?: boolean, x$?: number, y$?: number) {
 		this.x = x$ ?? 0
 		this.y = y$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): point {
@@ -41,7 +41,7 @@ export class holder {
 	constructor(__goscriptValue?: boolean, points$?: point[], names$?: string[]) {
 		this.points = points$ ?? $.arrayValue(globalThis.Array.from({ length: 2 }, () => new point(true)), /* @__PURE__ */ $.arrayType("main.point", 2))
 		this.names = names$ ?? $.arrayValue(globalThis.Array.from({ length: 3 }, () => ""))
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): holder {

tests/tests/array_pointer_element_slice/array_pointer_element_slice.gs.ts

@@ -11,7 +11,7 @@ export class node {
 	constructor(__goscriptValue?: boolean, sub$?: $.Slice<node | $.VarRef<node> | null>, sub0$?: (node | $.VarRef<node> | null)[]) {
 		this.sub = sub$ ?? (null! as $.Slice<node | $.VarRef<node> | null>)
 		this.sub0 = sub0$ ?? $.arrayValue(globalThis.Array.from({ length: 1 }, () => null))
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): node {

tests/tests/array_pointer_ops/array_pointer_ops.gs.ts

@@ -8,7 +8,7 @@ export class item {
 
 	constructor(__goscriptValue?: boolean, value$?: number) {
 		this.value = value$ ?? 0
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): item {
@@ -37,7 +37,7 @@ export class arrays {
 	constructor(__goscriptValue?: boolean, slices$?: $.Slice<number>[], items$?: item[]) {
 		this.slices = slices$ ?? $.arrayValue(globalThis.Array.from({ length: 1 }, () => null))
 		this.items = items$ ?? $.arrayValue(globalThis.Array.from({ length: 1 }, () => new item(true)), /* @__PURE__ */ $.arrayType("main.item", 1))
-		;(this as any)[$.structValueMarker] = __goscriptValue === true
+		;(this as any).__goStructValue = __goscriptValue === true
 	}
 
 	public clone(): arrays {