Add default getStringData/getPropNameIdData implementation (#47530)

Summary:
Pull Request resolved: #47530

Adds the default implementation for `getStringData`/`getPropNameIdData`
for VMs that do not provide their own implementation

Changelog: [Internal]

Reviewed By: neildhar

Differential Revision: D65638889

fbshipit-source-id: 0a97569433c09ffafbd08fec5d9c9fbf5639b778

Author: tsaichien

packages/react-native/ReactCommon/jsi/jsi/decorator.h

@@ -232,6 +232,22 @@ class RuntimeDecorator : public Base, private jsi::Instrumentation {
     return plain_.utf16(sym);
   }
 
+  void getStringData(
+      const jsi::String& str,
+      void* ctx,
+      void (
+          *cb)(void* ctx, bool ascii, const void* data, size_t num)) override {
+    plain_.getStringData(str, ctx, cb);
+  }
+
+  void getPropNameIdData(
+      const jsi::PropNameID& sym,
+      void* ctx,
+      void (
+          *cb)(void* ctx, bool ascii, const void* data, size_t num)) override {
+    plain_.getPropNameIdData(sym, ctx, cb);
+  }
+
   Object createObject() override {
     return plain_.createObject();
   };
@@ -690,6 +706,24 @@ class WithRuntimeDecorator : public RuntimeDecorator<Plain, Base> {
     return RD::utf16(sym);
   }
 
+  void getStringData(
+      const jsi::String& str,
+      void* ctx,
+      void (
+          *cb)(void* ctx, bool ascii, const void* data, size_t num)) override {
+    Around around{with_};
+    RD::getStringData(str, ctx, cb);
+  }
+
+  void getPropNameIdData(
+      const jsi::PropNameID& sym,
+      void* ctx,
+      void (
+          *cb)(void* ctx, bool ascii, const void* data, size_t num)) override {
+    Around around{with_};
+    RD::getPropNameIdData(sym, ctx, cb);
+  }
+
   Value createValueFromJsonUtf8(const uint8_t* json, size_t length) override {
     Around around{with_};
     return RD::createValueFromJsonUtf8(json, length);

packages/react-native/ReactCommon/jsi/jsi/jsi.cpp

@@ -258,6 +258,22 @@ std::u16string Runtime::utf16(const String& str) {
   return convertUTF8ToUTF16(utf8Str);
 }
 
+void Runtime::getStringData(
+    const jsi::String& str,
+    void* ctx,
+    void (*cb)(void* ctx, bool ascii, const void* data, size_t num)) {
+  auto utf16Str = utf16(str);
+  cb(ctx, false, utf16Str.data(), utf16Str.size());
+}
+
+void Runtime::getPropNameIdData(
+    const jsi::PropNameID& sym,
+    void* ctx,
+    void (*cb)(void* ctx, bool ascii, const void* data, size_t num)) {
+  auto utf16Str = utf16(sym);
+  cb(ctx, false, utf16Str.data(), utf16Str.size());
+}
+
 Pointer& Pointer::operator=(Pointer&& other) noexcept {
   if (ptr_) {
     ptr_->invalidate();

packages/react-native/ReactCommon/jsi/jsi/jsi.h

@@ -402,6 +402,34 @@ class JSI_EXPORT Runtime {
   virtual std::u16string utf16(const String& str);
   virtual std::u16string utf16(const PropNameID& sym);
 
+  /// Invokes the provided callback \p cb with the String content in \p str.
+  /// The callback must take in three arguments: bool ascii, const void* data,
+  /// and size_t num, respectively. \p ascii indicates whether the \p data
+  /// passed to the callback should be interpreted as a pointer to a sequence of
+  /// \p num ASCII characters or UTF16 characters. Depending on the internal
+  /// representation of the string, the function may invoke the callback
+  /// multiple times, with a different format on each invocation. The callback
+  /// must not access runtime functionality, as any operation on the runtime may
+  /// invalidate the data pointers.
+  virtual void getStringData(
+      const jsi::String& str,
+      void* ctx,
+      void (*cb)(void* ctx, bool ascii, const void* data, size_t num));
+
+  /// Invokes the provided callback \p cb with the PropNameID content in \p sym.
+  /// The callback must take in three arguments: bool ascii, const void* data,
+  /// and size_t num, respectively. \p ascii indicates whether the \p data
+  /// passed to the callback should be interpreted as a pointer to a sequence of
+  /// \p num ASCII characters or UTF16 characters. Depending on the internal
+  /// representation of the string, the function may invoke the callback
+  /// multiple times, with a different format on each invocation. The callback
+  /// must not access runtime functionality, as any operation on the runtime may
+  /// invalidate the data pointers.
+  virtual void getPropNameIdData(
+      const jsi::PropNameID& sym,
+      void* ctx,
+      void (*cb)(void* ctx, bool ascii, const void* data, size_t num));
+
   // These exist so derived classes can access the private parts of
   // Value, Symbol, String, and Object, which are all friends of Runtime.
   template <typename T>
@@ -509,6 +537,22 @@ class JSI_EXPORT PropNameID : public Pointer {
     return runtime.utf16(*this);
   }
 
+  /// Invokes the user provided callback to process the content in PropNameId.
+  /// The callback must take in three arguments: bool ascii, const void* data,
+  /// and size_t num, respectively. \p ascii indicates whether the \p data
+  /// passed to the callback should be interpreted as a pointer to a sequence of
+  /// \p num ASCII characters or UTF16 characters. The function may invoke the
+  /// callback multiple times, with a different format on each invocation. The
+  /// callback must not access runtime functionality, as any operation on the
+  /// runtime may invalidate the data pointers.
+  template <typename CB>
+  void getPropNameIdData(Runtime& runtime, CB& cb) const {
+    runtime.getPropNameIdData(
+        *this, &cb, [](void* ctx, bool ascii, const void* data, size_t num) {
+          (*((CB*)ctx))(ascii, data, num);
+        });
+  }
+
   static bool compare(
       Runtime& runtime,
       const jsi::PropNameID& a,
@@ -664,6 +708,22 @@ class JSI_EXPORT String : public Pointer {
     return runtime.utf16(*this);
   }
 
+  /// Invokes the user provided callback to process content in String. The
+  /// callback must take in three arguments: bool ascii, const void* data, and
+  /// size_t num, respectively. \p ascii indicates whether the \p data passed to
+  /// the callback should be interpreted as a pointer to a sequence of \p num
+  /// ASCII characters or UTF16 characters. The function may invoke the callback
+  /// multiple times, with a different format on each invocation. The callback
+  /// must not access runtime functionality, as any operation on the runtime may
+  /// invalidate the data pointers.
+  template <typename CB>
+  void getStringData(Runtime& runtime, CB& cb) const {
+    runtime.getStringData(
+        *this, &cb, [](void* ctx, bool ascii, const void* data, size_t num) {
+          (*((CB*)ctx))(ascii, data, num);
+        });
+  }
+
   friend class Runtime;
   friend class Value;
 };

packages/react-native/ReactCommon/jsi/jsi/test/testlib.cpp

@@ -1635,6 +1635,35 @@ TEST_P(JSITest, UTF16Test) {
   EXPECT_EQ(str.utf16(rd), u"\uFFFD\u007A");
 }
 
+TEST_P(JSITest, GetStringDataTest) {
+  // This Runtime Decorator is used to test the default getStringData
+  // implementation for VMs that do not provide their own implementation
+  class RD : public RuntimeDecorator<Runtime, Runtime> {
+   public:
+    RD(Runtime& rt) : RuntimeDecorator(rt) {}
+
+    void getStringData(
+        const String& str,
+        void* ctx,
+        void (*cb)(void* ctx, bool ascii, const void* data, size_t num))
+        override {
+      Runtime::getStringData(str, ctx, cb);
+    }
+  };
+
+  RD rd = RD(rt);
+  String str = String::createFromUtf8(rd, "hello👋");
+
+  std::u16string buf;
+  auto cb = [&buf](bool ascii, const void* data, size_t num) {
+    assert(!ascii && "Default implementation is always utf16");
+    buf.append((const char16_t*)data, num);
+  };
+
+  str.getStringData(rd, cb);
+  EXPECT_EQ(buf, str.utf16(rd));
+}
+
 INSTANTIATE_TEST_CASE_P(
     Runtimes,
     JSITest,