feat: implement ES2024 Object.groupBy

facebook · Jun 28, 2024 · 01bab5b · 01bab5b
1 parent 3034371
commit 01bab5b
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diff --git a/include/hermes/VM/NativeFunctions.def b/include/hermes/VM/NativeFunctions.def
@@ -249,6 +249,7 @@ NATIVE_FUNCTION(objectIsFrozen)
 NATIVE_FUNCTION(objectIsSealed)
 NATIVE_FUNCTION(objectKeys)
 NATIVE_FUNCTION(objectPreventExtensions)
+NATIVE_FUNCTION(objectGroupBy)
 NATIVE_FUNCTION(objectPrototypeDefineGetter)
 NATIVE_FUNCTION(objectPrototypeDefineSetter)
 NATIVE_FUNCTION(objectPrototypeHasOwnProperty)

diff --git a/include/hermes/VM/PredefinedStrings.def b/include/hermes/VM/PredefinedStrings.def
@@ -73,6 +73,7 @@ STR(getOwnPropertyDescriptor, "getOwnPropertyDescriptor")
 STR(getOwnPropertyDescriptors, "getOwnPropertyDescriptors")
 STR(getOwnPropertyNames, "getOwnPropertyNames")
 STR(getOwnPropertySymbols, "getOwnPropertySymbols")
+STR(groupBy, "groupBy")
 STR(seal, "seal")
 STR(freeze, "freeze")
 STR(fromEntries, "fromEntries")

diff --git a/lib/VM/JSLib/Object.cpp b/lib/VM/JSLib/Object.cpp
@@ -275,6 +275,13 @@ Handle<JSObject> createObjectConstructor(Runtime &runtime) {
       ctx,
       objectSetPrototypeOf,
       2);
+  defineMethod(
+      runtime,
+      cons,
+      Predefined::getSymbolID(Predefined::groupBy),
+      ctx,
+      objectGroupBy,
+      2);
 
   return cons;
 }
@@ -1154,6 +1161,123 @@ objectSetPrototypeOf(void *, Runtime &runtime, NativeArgs args) {
   return *O;
 }
 
+CallResult<HermesValue>
+objectGroupBy(void *, Runtime &runtime, NativeArgs args) {
+  GCScope gcScope{runtime};
+
+  Handle<> items = args.getArgHandle(0);
+  Handle<Callable> grouperFunc = args.dyncastArg<Callable>(1);
+
+  // 1. Perform ? RequireObjectCoercible(items).
+  if (LLVM_UNLIKELY(items->isNull() || items->isUndefined())) {
+    return runtime.raiseTypeError(
+        "groupBy first argument is not coercible to Object");
+  }
+
+  // 2. If IsCallable(callbackfn) is false, throw a TypeError exception.
+  if (LLVM_UNLIKELY(!grouperFunc)) {
+    return runtime.raiseTypeError(
+        "groupBy second argument must be callable");
+  }
+
+  // 4. Let iteratorRecord be ? GetIterator(items, sync).
+  auto iteratorRecordRes = getIterator(runtime, items);
+  if (LLVM_UNLIKELY(iteratorRecordRes == ExecutionStatus::EXCEPTION)) {
+    return ExecutionStatus::EXCEPTION;
+  }
+  auto iteratorRecord = *iteratorRecordRes;
+
+  // 5. Let k be 0.
+  size_t k = 0;
+
+  Handle<JSObject> O = runtime.makeHandle(JSObject::create(runtime));
+  Handle<HermesValue> callbackThis = runtime.makeHandle(HermesValue::encodeUndefinedValue());
+
+  MutableHandle<> objectArrayHandle{runtime};
+  MutableHandle<HermesValue> groupKey{runtime};
+  MutableHandle<JSArray> targetGroupArray{runtime};
+  MutableHandle<> targetGroupIndex{runtime};
+  MutableHandle<JSObject> tmpHandle{runtime};
+  MutableHandle<> valueHandle{runtime};
+  auto marker = gcScope.createMarker();
+
+  // 6. Repeat,
+  // Check the length of the array after every iteration,
+  // to allow for the fact that the length could be modified during iteration.
+  for (;; k++) {
+    CallResult<Handle<JSObject>> nextRes = iteratorStep(runtime, iteratorRecord);
+    if (LLVM_UNLIKELY(nextRes == ExecutionStatus::EXCEPTION)) {
+      return ExecutionStatus::EXCEPTION;
+    }
+
+    if (!*nextRes) {
+      // Done with iteration.
+      break;
+    }
+
+    tmpHandle = vmcast<JSObject>(nextRes->getHermesValue());
+    auto nextValueRes = JSObject::getNamed_RJS(
+        tmpHandle, runtime, Predefined::getSymbolID(Predefined::value));
+    if (LLVM_UNLIKELY(nextValueRes == ExecutionStatus::EXCEPTION)) {
+      return ExecutionStatus::EXCEPTION;
+    }
+    valueHandle = runtime.makeHandle(std::move(*nextValueRes));
+
+    // compute key for current element
+    auto keyRes = Callable::executeCall2(grouperFunc, runtime, callbackThis, valueHandle.getHermesValue(), HermesValue::encodeTrustedNumberValue(k));
+    if (LLVM_UNLIKELY(keyRes == ExecutionStatus::EXCEPTION)) {
+      return iteratorCloseAndRethrow(runtime, iteratorRecord.iterator);
+    }
+
+    groupKey = runtime.makeHandle(std::move(*keyRes));
+
+    // make it a property key
+    auto propertyKeyRes = toPropertyKey(runtime, groupKey);
+    if (LLVM_UNLIKELY(propertyKeyRes == ExecutionStatus::EXCEPTION)) {
+      return iteratorCloseAndRethrow(runtime, iteratorRecord.iterator);
+    }
+
+    // get the group array
+    auto groupArrayRes = JSObject::getComputed_RJS(O, runtime, *propertyKeyRes);
+    if (LLVM_UNLIKELY(groupArrayRes == ExecutionStatus::EXCEPTION)) {
+      return iteratorCloseAndRethrow(runtime, iteratorRecord.iterator);
+    }
+
+    // new group key, no array in object yet so create it
+    if (groupArrayRes.getValue()->isUndefined() || groupArrayRes.getValue()->isNull()) {
+      auto targetGroupArrayRes = JSArray::create(runtime, 0, 0);
+      if (LLVM_UNLIKELY(targetGroupArrayRes == ExecutionStatus::EXCEPTION)) {
+        return iteratorCloseAndRethrow(runtime, iteratorRecord.iterator);
+      }
+
+      targetGroupArray = std::move(*targetGroupArrayRes);
+
+      // group already created, get the array
+      if (LLVM_UNLIKELY(JSObject::defineOwnComputed(O, runtime, groupKey, DefinePropertyFlags().getDefaultNewPropertyFlags(), targetGroupArray, PropOpFlags().plusThrowOnError()) == ExecutionStatus::EXCEPTION)) {
+        return iteratorCloseAndRethrow(runtime, iteratorRecord.iterator);
+      }
+    } else {
+      objectArrayHandle = runtime.makeHandle(std::move(groupArrayRes.getValue()));
+      targetGroupArray = Handle<JSArray>::dyn_vmcast(objectArrayHandle);
+    }
+
+    targetGroupIndex = HermesValue::encodeTrustedNumberValue(JSArray::getLength(*targetGroupArray, runtime));
+
+    if (LLVM_UNLIKELY(
+        JSObject::putComputed_RJS(
+            targetGroupArray, runtime,
+                targetGroupIndex, valueHandle, PropOpFlags().plusThrowOnError()) ==
+        ExecutionStatus::EXCEPTION)) {
+      return iteratorCloseAndRethrow(runtime, iteratorRecord.iterator);
+    }
+
+    gcScope.flushToMarker(marker);
+  }
+
+  // 8. Return O.
+  return O.getHermesValue();
+}
+
 //===----------------------------------------------------------------------===//
 /// Object.prototype.
 

diff --git a/test/hermes/object-functions.js b/test/hermes/object-functions.js
@@ -573,3 +573,32 @@ function testObjectAssignModifications() {
 }
 testObjectAssignModifications()
 //CHECK-NEXT: {"a":10,"c":32}
+
+print('groupBy');
+// CHECK-LABEL: groupBy
+
+var obj = Object.groupBy([1, 2, 3, 4, 5, 6, 7], function(key) { return key % 2; });
+print(JSON.stringify(obj));
+//CHECK-NEXT: {"0":[2,4,6],"1":[1,3,5,7]}
+
+var obj = Object.groupBy([1, 2, 3, 4, 5, 6, 7], function(key) { return key % 3; });
+print(JSON.stringify(obj));
+//CHECK-NEXT: {"0":[3,6],"1":[1,4,7],"2":[2,5]}
+
+var obj = Object.groupBy([1, 2, 3, 4, 5, 6, 7], function(key) { return key % 1; });
+print(JSON.stringify(obj));
+//CHECK-NEXT: {"0":[1,2,3,4,5,6,7]}
+
+var obj = Object.groupBy([1, 2, 3, 4], function(key) { return key; });
+print(JSON.stringify(obj));
+//CHECK-NEXT: {"1":[1],"2":[2],"3":[3],"4":[4]}
+
+var team = [
+    {name: 'Peter', age: 15},
+    {name: 'Mike', age: 20},
+    {name: 'John', age: 22},
+];
+
+var obj = Object.groupBy(team, function(p) { return p.age < 18 ? 'underage' : 'adult'; });
+print(JSON.stringify(obj));
+//CHECK-NEXT: {"underage":[{"name":"Peter","age":15}],"adult":[{"name":"Mike","age":20},{"name":"John","age":22}]}