LibWebView: Parse inspector-related JSON strings sooner

We currently receive serialized JSON values over IPC and forward them to
them WebView callbacks, leaving it to the implementations of those
callbacks to parse the strings as JSON objects. This patch hoists that
parsing up to WebContentClient as soon as the IPC message is received.
This is to reduce the work needed for secondary implementations of these
callbacks (i.e. our Firefox DevTools server).

Libraries/LibWebView/Application.cpp

@@ -371,14 +371,9 @@ void Application::inspect_tab(DevTools::TabDescription const& description, DevTo
         return;
     }
 
-    view->on_received_dom_tree = [&view = *view, on_complete = move(on_complete)](String const& dom_tree) {
+    view->on_received_dom_tree = [&view = *view, on_complete = move(on_complete)](JsonObject dom_tree) {
         view.on_received_dom_tree = nullptr;
-
+        on_complete(move(dom_tree));
-        if (auto parsed_tree = JsonValue::from_string(dom_tree); parsed_tree.is_error()) {
-            on_complete(parsed_tree.release_error());
-        } else {
-            on_complete(parsed_tree.release_value());
-        }
     };
 
     view->inspect_dom_tree();

Libraries/LibWebView/InspectorClient.cpp

@@ -28,15 +28,6 @@ static constexpr auto INSPECTOR_HTML = "resource://ladybird/inspector.html"sv;
 static constexpr auto INSPECTOR_CSS = "resource://ladybird/inspector.css"sv;
 static constexpr auto INSPECTOR_JS = "resource://ladybird/inspector.js"sv;
 
-static ErrorOr<JsonValue> parse_json_tree(StringView json)
-{
-    auto parsed_tree = TRY(JsonValue::from_string(json));
-    if (!parsed_tree.is_object())
-        return Error::from_string_literal("Expected tree to be a JSON object");
-
-    return parsed_tree;
-}
-
 static String style_sheet_identifier_to_json(Web::CSS::StyleSheetIdentifier const& identifier)
 {
     return MUST(String::formatted("{{ type: '{}', domNodeId: {}, url: '{}' }}"sv,
@@ -50,13 +41,7 @@ InspectorClient::InspectorClient(ViewImplementation& content_web_view, ViewImple
     , m_inspector_web_view(inspector_web_view)
 {
     m_content_web_view.on_received_dom_tree = [this](auto const& dom_tree) {
-        auto result = parse_json_tree(dom_tree);
+        auto dom_tree_html = generate_dom_tree(dom_tree);
-        if (result.is_error()) {
-            dbgln("Failed to load DOM tree: {}", result.error());
-            return;
-        }
-
-        auto dom_tree_html = generate_dom_tree(result.value().as_object());
         auto dom_tree_base64 = MUST(encode_base64(dom_tree_html.bytes()));
 
         auto script = MUST(String::formatted("inspector.loadDOMTree(\"{}\");", dom_tree_base64));
@@ -70,44 +55,27 @@ InspectorClient::InspectorClient(ViewImplementation& content_web_view, ViewImple
             select_default_node();
     };
 
-    m_content_web_view.on_received_dom_node_properties = [this](auto const& inspected_node_properties) {
+    m_content_web_view.on_received_dom_node_properties = [this](auto const& properties) {
         StringBuilder builder;
 
         // FIXME: Support box model metrics and ARIA properties.
-        auto generate_property_script = [&](auto const& computed_style, auto const& resolved_style, auto const& custom_properties, auto const& fonts) {
+        builder.append("inspector.createPropertyTables(\""sv);
-            builder.append("inspector.createPropertyTables(\""sv);
+        builder.append_escaped_for_json(properties.computed_style.serialized());
-            builder.append_escaped_for_json(computed_style);
+        builder.append("\", \""sv);
-            builder.append("\", \""sv);
+        builder.append_escaped_for_json(properties.resolved_style.serialized());
-            builder.append_escaped_for_json(resolved_style);
+        builder.append("\", \""sv);
-            builder.append("\", \""sv);
+        builder.append_escaped_for_json(properties.custom_properties.serialized());
-            builder.append_escaped_for_json(custom_properties);
+        builder.append("\");"sv);
-            builder.append("\");"sv);
-            builder.append("inspector.createFontList(\""sv);
-            builder.append_escaped_for_json(fonts);
-            builder.append("\");"sv);
-        };
 
-        if (inspected_node_properties.has_value()) {
+        builder.append("inspector.createFontList(\""sv);
-            generate_property_script(
+        builder.append_escaped_for_json(properties.fonts.serialized());
-                inspected_node_properties->computed_style_json,
+        builder.append("\");"sv);
-                inspected_node_properties->resolved_style_json,
-                inspected_node_properties->custom_properties_json,
-                inspected_node_properties->fonts_json);
-        } else {
-            generate_property_script("{}"sv, "{}"sv, "{}"sv, "{}"sv);
-        }
 
         m_inspector_web_view.run_javascript(builder.string_view());
     };
 
     m_content_web_view.on_received_accessibility_tree = [this](auto const& accessibility_tree) {
-        auto result = parse_json_tree(accessibility_tree);
+        auto accessibility_tree_html = generate_accessibility_tree(accessibility_tree);
-        if (result.is_error()) {
-            dbgln("Failed to load accessibility tree: {}", result.error());
-            return;
-        }
-
-        auto accessibility_tree_html = generate_accessibility_tree(result.value().as_object());
         auto accessibility_tree_base64 = MUST(encode_base64(accessibility_tree_html.bytes()));
 
         auto script = MUST(String::formatted("inspector.loadAccessibilityTree(\"{}\");", accessibility_tree_base64));

Libraries/LibWebView/ViewImplementation.h

@@ -9,6 +9,8 @@
 
 #include <AK/Forward.h>
 #include <AK/Function.h>
+#include <AK/JsonArray.h>
+#include <AK/JsonObject.h>
 #include <AK/LexicalPath.h>
 #include <AK/Queue.h>
 #include <AK/String.h>
@@ -35,12 +37,12 @@ public:
     virtual ~ViewImplementation();
 
     struct DOMNodeProperties {
-        String computed_style_json;
+        JsonObject computed_style;
-        String resolved_style_json;
+        JsonObject resolved_style;
-        String custom_properties_json;
+        JsonObject custom_properties;
-        String node_box_sizing_json;
+        JsonObject node_box_sizing;
-        String aria_properties_state_json;
+        JsonObject aria_properties_state;
-        String fonts_json;
+        JsonArray fonts;
     };
 
     static void for_each_view(Function<IterationDecision(ViewImplementation&)>);
@@ -200,9 +202,9 @@ public:
     Function<void()> on_request_accept_dialog;
     Function<void()> on_request_dismiss_dialog;
     Function<void(URL::URL const&, URL::URL const&, String const&)> on_received_source;
-    Function<void(String const&)> on_received_dom_tree;
+    Function<void(JsonObject)> on_received_dom_tree;
-    Function<void(Optional<DOMNodeProperties>)> on_received_dom_node_properties;
+    Function<void(DOMNodeProperties)> on_received_dom_node_properties;
-    Function<void(String const&)> on_received_accessibility_tree;
+    Function<void(JsonObject)> on_received_accessibility_tree;
     Function<void(Vector<Web::CSS::StyleSheetIdentifier>)> on_received_style_sheet_list;
     Function<void(Web::CSS::StyleSheetIdentifier const&)> on_inspector_requested_style_sheet_source;
     Function<void(Web::CSS::StyleSheetIdentifier const&, URL::URL const&, String const&)> on_received_style_sheet_source;

Libraries/LibWebView/WebContentClient.cpp

@@ -264,11 +264,39 @@ void WebContentClient::did_get_source(u64 page_id, URL::URL const& url, URL::URL
     }
 }
 
+template<typename JsonType = JsonObject>
+static JsonType parse_json(StringView json, StringView name)
+{
+    auto parsed_tree = JsonValue::from_string(json);
+    if (parsed_tree.is_error()) {
+        dbgln("Unable to parse {}: {}", name, parsed_tree.error());
+        return {};
+    }
+
+    if constexpr (IsSame<JsonType, JsonObject>) {
+        if (!parsed_tree.value().is_object()) {
+            dbgln("Expected {} to be an object: {}", name, parsed_tree.value());
+            return {};
+        }
+
+        return move(parsed_tree.release_value().as_object());
+    } else if constexpr (IsSame<JsonType, JsonArray>) {
+        if (!parsed_tree.value().is_array()) {
+            dbgln("Expected {} to be an array: {}", name, parsed_tree.value());
+            return {};
+        }
+
+        return move(parsed_tree.release_value().as_array());
+    } else {
+        static_assert(DependentFalse<JsonType>);
+    }
+}
+
 void WebContentClient::did_inspect_dom_tree(u64 page_id, String const& dom_tree)
 {
     if (auto view = view_for_page_id(page_id); view.has_value()) {
         if (view->on_received_dom_tree)
-            view->on_received_dom_tree(dom_tree);
+            view->on_received_dom_tree(parse_json(dom_tree, "DOM tree"sv));
     }
 }
 
@@ -278,16 +306,16 @@ void WebContentClient::did_inspect_dom_node(u64 page_id, bool has_style, String
     if (!view.has_value() || !view->on_received_dom_node_properties)
         return;
 
-    Optional<ViewImplementation::DOMNodeProperties> properties;
+    ViewImplementation::DOMNodeProperties properties;
 
     if (has_style) {
         properties = ViewImplementation::DOMNodeProperties {
-            .computed_style_json = computed_style,
+            .computed_style = parse_json(computed_style, "computed style"sv),
-            .resolved_style_json = resolved_style,
+            .resolved_style = parse_json(resolved_style, "resolved style"sv),
-            .custom_properties_json = custom_properties,
+            .custom_properties = parse_json(custom_properties, "custom properties"sv),
-            .node_box_sizing_json = node_box_sizing,
+            .node_box_sizing = parse_json(node_box_sizing, "node box sizing"sv),
-            .aria_properties_state_json = aria_properties_state,
+            .aria_properties_state = parse_json(aria_properties_state, "aria properties state"sv),
-            .fonts_json = fonts,
+            .fonts = parse_json<JsonArray>(fonts, "fonts"sv),
         };
     }
 
@@ -298,7 +326,7 @@ void WebContentClient::did_inspect_accessibility_tree(u64 page_id, String const&
 {
     if (auto view = view_for_page_id(page_id); view.has_value()) {
         if (view->on_received_accessibility_tree)
-            view->on_received_accessibility_tree(accessibility_tree);
+            view->on_received_accessibility_tree(parse_json(accessibility_tree, "accessibility tree"sv));
     }
 }