src: fix regression introduced by #874

Fixes: nodejs/node-addon-api#1158

Revert part of nodejs/node-addon-api#874
to avoid breaking existing code.

PR-URL: nodejs/node-addon-api#1159 (review)
Reviewed-By: Kevin Eady <kevin.c.eady@gmail.com>

Signed-off-by: Michael Dawson <mdawson@devrus.com>

napi-inl.h

@@ -1299,24 +1299,36 @@ inline Object::Object(napi_env env, napi_value value) : Value(env, value) {
 }
 
 inline Object::PropertyLValue<std::string> Object::operator[](
-    const char* utf8name) const {
+    const char* utf8name) {
   return PropertyLValue<std::string>(*this, utf8name);
 }
 
 inline Object::PropertyLValue<std::string> Object::operator[](
-    const std::string& utf8name) const {
+    const std::string& utf8name) {
   return PropertyLValue<std::string>(*this, utf8name);
 }
 
-inline Object::PropertyLValue<uint32_t> Object::operator[](
-    uint32_t index) const {
+inline Object::PropertyLValue<uint32_t> Object::operator[](uint32_t index) {
   return PropertyLValue<uint32_t>(*this, index);
 }
 
 inline Object::PropertyLValue<Value> Object::operator[](Value index) const {
   return PropertyLValue<Value>(*this, index);
 }
 
+inline MaybeOrValue<Value> Object::operator[](const char* utf8name) const {
+  return Get(utf8name);
+}
+
+inline MaybeOrValue<Value> Object::operator[](
+    const std::string& utf8name) const {
+  return Get(utf8name);
+}
+
+inline MaybeOrValue<Value> Object::operator[](uint32_t index) const {
+  return Get(index);
+}
+
 inline MaybeOrValue<bool> Object::Has(napi_value key) const {
   bool result;
   napi_status status = napi_has_property(_env, _value, key, &result);

napi.h

@@ -742,22 +742,36 @@ namespace NAPI_CPP_CUSTOM_NAMESPACE {
     /// Gets or sets a named property.
     PropertyLValue<std::string> operator[](
         const char* utf8name  ///< UTF-8 encoded null-terminated property name
-    ) const;
+    );
 
     /// Gets or sets a named property.
     PropertyLValue<std::string> operator[](
         const std::string& utf8name  ///< UTF-8 encoded property name
-    ) const;
+    );
 
     /// Gets or sets an indexed property or array element.
     PropertyLValue<uint32_t> operator[](
         uint32_t index  /// Property / element index
-    ) const;
+    );
 
     /// Gets or sets an indexed property or array element.
     PropertyLValue<Value> operator[](Value index  /// Property / element index
     ) const;
 
+    /// Gets a named property.
+    MaybeOrValue<Value> operator[](
+        const char* utf8name  ///< UTF-8 encoded null-terminated property name
+    ) const;
+
+    /// Gets a named property.
+    MaybeOrValue<Value> operator[](
+        const std::string& utf8name  ///< UTF-8 encoded property name
+    ) const;
+
+    /// Gets an indexed property or array element.
+    MaybeOrValue<Value> operator[](uint32_t index  ///< Property / element index
+    ) const;
+
     /// Checks whether a property is present.
     MaybeOrValue<bool> Has(napi_value key  ///< Property key primitive
     ) const;

test/object/subscript_operator.cc

@@ -1,22 +1,38 @@
 #include "napi.h"
+#include "test_helper.h"
 
 using namespace Napi;
 
 Value SubscriptGetWithCStyleString(const CallbackInfo& info) {
-  Object obj = info[0].As<Object>();
   String jsKey = info[1].As<String>();
+
+  // make sure const case compiles
+  const Object obj2 = info[0].As<Object>();
+  MaybeUnwrap(obj2[jsKey.Utf8Value().c_str()]).As<Boolean>();
+
+  Object obj = info[0].As<Object>();
   return obj[jsKey.Utf8Value().c_str()];
 }
 
 Value SubscriptGetWithCppStyleString(const CallbackInfo& info) {
-  Object obj = info[0].As<Object>();
   String jsKey = info[1].As<String>();
+
+  // make sure const case compiles
+  const Object obj2 = info[0].As<Object>();
+  MaybeUnwrap(obj2[jsKey.Utf8Value()]).As<Boolean>();
+
+  Object obj = info[0].As<Object>();
   return obj[jsKey.Utf8Value()];
 }
 
 Value SubscriptGetAtIndex(const CallbackInfo& info) {
-  Object obj = info[0].As<Object>();
   uint32_t index = info[1].As<Napi::Number>();
+
+  // make sure const case compiles
+  const Object obj2 = info[0].As<Object>();
+  MaybeUnwrap(obj2[index]).As<Boolean>();
+
+  Object obj = info[0].As<Object>();
   return obj[index];
 }