AK: JsonParser improvements

- Parsing invalid JSON no longer asserts
    Instead of asserting when coming across malformed JSON,
    JsonParser::parse now returns an Optional<JsonValue>.
- Disallow trailing commas in JSON objects and arrays
- No longer parse 'undefined', as that is a purely JS thing
- No longer allow non-whitespace after anything consumed by the initial
  parse() call. Examples of things that were valid and no longer are:
    - undefineddfz
    - {"foo": 1}abcd
    - [1,2,3]4
- JsonObject.for_each_member now iterates in original insertion order

Libraries/LibCore/EventLoop.cpp

@@ -105,13 +105,13 @@ public:
             auto request = m_socket->read(length);
 
             auto request_json = JsonValue::from_string(request);
-            if (!request_json.is_object()) {
+            if (!request_json.has_value() || !request_json.value().is_object()) {
                 dbg() << "RPC client sent invalid request";
                 shutdown();
                 return;
             }
 
-            handle_request(request_json.as_object());
+            handle_request(request_json.value().as_object());
         };
     }
     virtual ~RPCClient() override

Libraries/LibCore/ProcessStatisticsReader.cpp

@@ -48,7 +48,8 @@ HashMap<pid_t, Core::ProcessStatistics> ProcessStatisticsReader::get_all()
 
     auto file_contents = file->read_all();
     auto json = JsonValue::from_string(file_contents);
-    json.as_array().for_each([&](auto& value) {
+    ASSERT(json.has_value());
+    json.value().as_array().for_each([&](auto& value) {
         const JsonObject& process_object = value.as_object();
         Core::ProcessStatistics process;
 

Libraries/LibGUI/JsonArrayModel.cpp

@@ -42,8 +42,9 @@ void JsonArrayModel::update()
 
     auto json = JsonValue::from_string(file->read_all());
 
-    ASSERT(json.is_array());
-    m_array = json.as_array();
+    ASSERT(json.has_value());
+    ASSERT(json.value().is_array());
+    m_array = json.value().as_array();
 
     did_update();
 }

Libraries/LibKeyboard/CharacterMapFile.cpp

@@ -48,7 +48,9 @@ Optional<CharacterMapData> CharacterMapFile::load_from_file(const String& file_n
     }
 
     auto file_contents = file->read_all();
-    auto json = JsonValue::from_string(file_contents).as_object();
+    auto json_result = JsonValue::from_string(file_contents);
+    ASSERT(json_result.has_value());
+    auto json = json_result.value().as_object();
 
     ByteBuffer map = read_map(json, "map");
     ByteBuffer shift_map = read_map(json, "shift_map");

Libraries/LibWeb/CodeGenerators/Generate_CSS_PropertyID_cpp.cpp

@@ -56,7 +56,8 @@ int main(int argc, char** argv)
         return 1;
 
     auto json = JsonValue::from_string(file->read_all());
-    ASSERT(json.is_object());
+    ASSERT(json.has_value());
+    ASSERT(json.value().is_object());
 
     out() << "#include <AK/Assertions.h>";
     out() << "#include <LibWeb/CSS/PropertyID.h>";
@@ -65,7 +66,7 @@ int main(int argc, char** argv)
 
     out() << "PropertyID property_id_from_string(const StringView& string) {";
 
-    json.as_object().for_each_member([&](auto& name, auto& value) {
+    json.value().as_object().for_each_member([&](auto& name, auto& value) {
         ASSERT(value.is_object());
         out() << "    if (string.equals_ignoring_case(\"" << name << "\"))";
         out() << "        return PropertyID::" << title_casify(name) << ";";
@@ -77,7 +78,7 @@ int main(int argc, char** argv)
 
     out() << "const char* string_from_property_id(PropertyID property_id) {";
     out() << "    switch (property_id) {";
-    json.as_object().for_each_member([&](auto& name, auto& value) {
+    json.value().as_object().for_each_member([&](auto& name, auto& value) {
         ASSERT(value.is_object());
         out() << "    case PropertyID::" << title_casify(name) << ":";
         out() << "        return \"" << name << "\";";

Libraries/LibWeb/CodeGenerators/Generate_CSS_PropertyID_h.cpp

@@ -56,7 +56,8 @@ int main(int argc, char** argv)
         return 1;
 
     auto json = JsonValue::from_string(file->read_all());
-    ASSERT(json.is_object());
+    ASSERT(json.has_value());
+    ASSERT(json.value().is_object());
 
     out() << "#pragma once";
     out() << "#include <AK/StringView.h>";
@@ -67,7 +68,7 @@ int main(int argc, char** argv)
     out() << "enum class PropertyID {";
     out() << "    Invalid,";
 
-    json.as_object().for_each_member([&](auto& name, auto& value) {
+    json.value().as_object().for_each_member([&](auto& name, auto& value) {
         ASSERT(value.is_object());
         out() << "    " << title_casify(name) << ",";
     });