Inspector: Add a GUI tool for viewing a remote process's CObject graph

Here comes the foundation for a neat remote debugging tool.

Right now, it connects to a remote process's CEventLoop RPC socket and
retreives the remote object graph JSON dump. The remote object graph
is then reconstructed and exposed through a GModel subclass, which is
then displayed in a GTreeView.

It's pretty cool, I think. :^)

DevTools/Inspector/RemoteObjectGraphModel.cpp

@@ -0,0 +1,107 @@
+#include "RemoteObjectGraphModel.h"
+#include <AK/JsonObject.h>
+#include <AK/JsonValue.h>
+#include <LibDraw/PNGLoader.h>
+#include <LibGUI/GApplication.h>
+#include <stdio.h>
+
+RemoteObjectGraphModel::RemoteObjectGraphModel(pid_t pid)
+    : m_pid(pid)
+{
+    m_object_icon.set_bitmap_for_size(16, load_png("/res/icons/gear16.png"));
+}
+
+RemoteObjectGraphModel::~RemoteObjectGraphModel()
+{
+}
+
+GModelIndex RemoteObjectGraphModel::index(int row, int column, const GModelIndex& parent) const
+{
+    if (!parent.is_valid()) {
+        if (m_remote_roots.is_empty())
+            return {};
+        return create_index(row, column, &m_remote_roots.at(row));
+    }
+    auto& remote_parent = *static_cast<RemoteObject*>(parent.internal_data());
+    return create_index(row, column, remote_parent.children.at(row));
+}
+
+int RemoteObjectGraphModel::row_count(const GModelIndex& index) const
+{
+    if (!index.is_valid())
+        return m_remote_roots.size();
+    auto& remote_object = *static_cast<RemoteObject*>(index.internal_data());
+    return remote_object.children.size();
+}
+
+int RemoteObjectGraphModel::column_count(const GModelIndex&) const
+{
+    return 1;
+}
+
+GVariant RemoteObjectGraphModel::data(const GModelIndex& index, Role role) const
+{
+    auto* remote_object = static_cast<RemoteObject*>(index.internal_data());
+    if (role == Role::Icon) {
+        return m_object_icon;
+    }
+    if (role == Role::Display) {
+        return String::format("%s{%s} (%d)", remote_object->class_name.characters(), remote_object->address.characters(), remote_object->children.size());
+    }
+    return {};
+}
+
+void RemoteObjectGraphModel::update()
+{
+    auto success = m_socket.connect(CSocketAddress::local(String::format("/tmp/rpc.%d", m_pid)));
+    if (!success) {
+        fprintf(stderr, "Couldn't connect to PID %d\n", m_pid);
+        exit(1);
+    }
+
+    m_socket.on_connected = [this] {
+        dbg() << "Connected to PID " << m_pid;
+    };
+
+    m_socket.on_ready_to_read = [this] {
+        if (m_socket.eof()) {
+            dbg() << "Disconnected from PID " << m_pid;
+            m_socket.close();
+            return;
+        }
+
+        auto data = m_socket.read_all();
+        auto json_value = JsonValue::from_string(data);
+        ASSERT(json_value.is_array());
+        m_json = json_value.as_array();
+
+        Vector<NonnullOwnPtr<RemoteObject>> remote_objects;
+        HashMap<String, RemoteObject*> objects_by_address;
+
+        for (auto& value : m_json.values()) {
+            ASSERT(value.is_object());
+            auto& object = value.as_object();
+            auto remote_object = make<RemoteObject>();
+            remote_object->address = object.get("address").to_string();
+            remote_object->parent_address = object.get("parent").to_string();
+            remote_object->name = object.get("name").to_string();
+            remote_object->class_name = object.get("class_name").to_string();
+            objects_by_address.set(remote_object->address, remote_object);
+            remote_objects.append(move(remote_object));
+        }
+
+        for (int i = 0; i < remote_objects.size(); ++i) {
+            auto& remote_object = remote_objects[i];
+            auto* parent = objects_by_address.get(remote_object->parent_address).value_or(nullptr);
+            if (!parent) {
+                m_remote_roots.append(move(remote_object));
+            } else {
+                remote_object->parent = parent;
+                parent->children.append(move(remote_object));
+            }
+        }
+
+        //dbg() << m_json.to_string();
+        did_update();
+    };
+}