LibCore: Make Core::Object properties more dynamic

Instead of everyone overriding save_to() and set_property() and doing
a pretty asymmetric job of implementing the various properties, let's
add a bit of structure here.

Object properties are now represented by a Core::Property. Properties
are registered with a getter and setter (optional) in constructors.
I've added some convenience macros for creating and registering
properties, but this does still feel a bit bulky. We'll have to
iterate on this and see where it goes.

5 files changed, 241 insertions, 11 deletions

diff --git a/Libraries/LibCore/CMakeLists.txt b/Libraries/LibCore/CMakeLists.txt
index bd64c35131..8b1dfd6059 100644
--- a/Libraries/LibCore/CMakeLists.txt
+++ b/Libraries/LibCore/CMakeLists.txt
@@ -19,6 +19,7 @@ set(SOURCES
     Notifier.cpp
     Object.cpp
     ProcessStatisticsReader.cpp
+    Property.cpp
     puff.cpp
     SocketAddress.cpp
     Socket.cpp
diff --git a/Libraries/LibCore/Object.cpp b/Libraries/LibCore/Object.cpp
index 2c4b87cece..44ab028de2 100644
--- a/Libraries/LibCore/Object.cpp
+++ b/Libraries/LibCore/Object.cpp
@@ -47,6 +47,17 @@ Object::Object(Object* parent, bool is_widget)
     all_objects().append(*this);
     if (m_parent)
         m_parent->add_child(*this);
+
+    REGISTER_READONLY_STRING_PROPERTY("class_name", class_name);
+    REGISTER_STRING_PROPERTY("name", name, set_name);
+
+    register_property(
+        "address", [this] { return FlatPtr(this); },
+        [](auto&) { return false; });
+
+    register_property(
+        "parent", [this] { return FlatPtr(this->parent()); },
+        [](auto&) { return false; });
 }
 
 Object::~Object()
@@ -173,19 +184,26 @@ void Object::deferred_invoke(Function<void(Object&)> invokee)
 
 void Object::save_to(JsonObject& json)
 {
-    json.set("class_name", class_name());
-    json.set("address", (FlatPtr)this);
-    json.set("name", name());
-    json.set("parent", (FlatPtr)parent());
+    for (auto& it : m_properties) {
+        auto& property = it.value;
+        json.set(property->name(), property->get());
+    }
+}
+
+JsonValue Object::property(const StringView& name)
+{
+    auto it = m_properties.find(name);
+    if (it == m_properties.end())
+        return JsonValue();
+    return it->value->get();
 }
 
 bool Object::set_property(const StringView& name, const JsonValue& value)
 {
-    if (name == "name") {
-        set_name(value.to_string());
-        return true;
-    }
-    return false;
+    auto it = m_properties.find(name);
+    if (it == m_properties.end())
+        return false;
+    return it->value->set(value);
 }
 
 bool Object::is_ancestor_of(const Object& other) const
@@ -235,6 +253,11 @@ void Object::decrement_inspector_count(Badge<RPCClient>)
         did_end_inspection();
 }
 
+void Object::register_property(const String& name, Function<JsonValue()> getter, Function<bool(const JsonValue&)> setter)
+{
+    m_properties.set(name, make<Property>(name, move(getter), move(setter)));
+}
+
 const LogStream& operator<<(const LogStream& stream, const Object& object)
 {
     return stream << object.class_name() << '{' << &object << '}';
diff --git a/Libraries/LibCore/Object.h b/Libraries/LibCore/Object.h
index e54e0d9920..24ef7a19cb 100644
--- a/Libraries/LibCore/Object.h
+++ b/Libraries/LibCore/Object.h
@@ -27,6 +27,7 @@
 #pragma once
 
 #include <AK/Forward.h>
+#include <AK/HashMap.h>
 #include <AK/IntrusiveList.h>
 #include <AK/Noncopyable.h>
 #include <AK/NonnullRefPtrVector.h>
@@ -34,6 +35,7 @@
 #include <AK/TypeCasts.h>
 #include <AK/Weakable.h>
 #include <LibCore/Forward.h>
+#include <LibCore/Property.h>
 
 namespace Core {
 
@@ -112,8 +114,10 @@ public:
     virtual bool is_action() const { return false; }
     virtual bool is_window() const { return false; }
 
-    virtual void save_to(AK::JsonObject&);
-    virtual bool set_property(const StringView& name, const JsonValue& value);
+    void save_to(AK::JsonObject&);
+
+    bool set_property(const StringView& name, const JsonValue& value);
+    JsonValue property(const StringView& name);
 
     static IntrusiveList<Object, &Object::m_all_objects_list_node>& all_objects();
 
@@ -143,6 +147,8 @@ public:
 protected:
     explicit Object(Object* parent = nullptr, bool is_widget = false);
 
+    void register_property(const String& name, Function<JsonValue()> getter, Function<bool(const JsonValue&)> setter = nullptr);
+
     virtual void timer_event(TimerEvent&);
     virtual void custom_event(CustomEvent&);
 
@@ -158,6 +164,7 @@ private:
     int m_timer_id { 0 };
     unsigned m_inspector_count { 0 };
     bool m_widget { false };
+    HashMap<String, NonnullOwnPtr<Property>> m_properties;
     NonnullRefPtrVector<Object> m_children;
 };
 
@@ -176,4 +183,103 @@ inline void Object::for_each_child_of_type(Callback callback)
 
 const LogStream& operator<<(const LogStream&, const Object&);
 
+#define REGISTER_INT_PROPERTY(property_name, getter, setter) \
+    register_property(                                       \
+        property_name,                                       \
+        [this] { return this->getter(); },                   \
+        [this](auto& value) {                                \
+            this->setter(value.template to_number<int>());   \
+            return true;                                     \
+        });
+
+#define REGISTER_BOOL_PROPERTY(property_name, getter, setter) \
+    register_property(                                        \
+        property_name,                                        \
+        [this] { return this->getter(); },                    \
+        [this](auto& value) {                                 \
+            this->setter(value.to_bool());                    \
+            return true;                                      \
+        });
+
+#define REGISTER_STRING_PROPERTY(property_name, getter, setter) \
+    register_property(                                          \
+        property_name,                                          \
+        [this] { return this->getter(); },                      \
+        [this](auto& value) {                                   \
+            this->setter(value.to_string());                    \
+            return true;                                        \
+        });
+
+#define REGISTER_READONLY_STRING_PROPERTY(property_name, getter) \
+    register_property(                                           \
+        property_name,                                           \
+        [this] { return this->getter(); },                       \
+        nullptr);
+
+#define REGISTER_RECT_PROPERTY(property_name, getter, setter)          \
+    register_property(                                                 \
+        property_name,                                                 \
+        [this] {                                                       \
+            auto rect = this->getter();                                \
+            JsonObject rect_object;                                    \
+            rect_object.set("x", rect.x());                            \
+            rect_object.set("y", rect.y());                            \
+            rect_object.set("width", rect.width());                    \
+            rect_object.set("height", rect.height());                  \
+            return rect_object;                                        \
+        },                                                             \
+        [this](auto& value) {                                          \
+            if (!value.is_object())                                    \
+                return false;                                          \
+            Gfx::IntRect rect;                                         \
+            rect.set_x(value.as_object().get("x").to_i32());           \
+            rect.set_y(value.as_object().get("y").to_i32());           \
+            rect.set_width(value.as_object().get("width").to_i32());   \
+            rect.set_height(value.as_object().get("height").to_i32()); \
+            setter(rect);                                              \
+            return true;                                               \
+        });
+
+#define REGISTER_SIZE_PROPERTY(property_name, getter, setter)          \
+    register_property(                                                 \
+        property_name,                                                 \
+        [this] {                                                       \
+            auto size = this->getter();                                \
+            JsonObject size_object;                                    \
+            size_object.set("width", size.width());                    \
+            size_object.set("height", size.height());                  \
+            return size_object;                                        \
+        },                                                             \
+        [this](auto& value) {                                          \
+            if (!value.is_object())                                    \
+                return false;                                          \
+            Gfx::IntSize size;                                         \
+            size.set_width(value.as_object().get("width").to_i32());   \
+            size.set_height(value.as_object().get("height").to_i32()); \
+            setter(size);                                              \
+            return true;                                               \
+        });
+
+#define REGISTER_SIZE_POLICY_PROPERTY(property_name, getter, setter) \
+    register_property(                                               \
+        property_name, [this]() -> JsonValue {                       \
+        auto policy = this->getter();                                \
+        if (policy == GUI::SizePolicy::Fill)                         \
+            return "Fill";                                           \
+        if (policy == GUI::SizePolicy::Fixed)                        \
+            return "Fixed";                                          \
+        return JsonValue(); },                    \
+        [this](auto& value) {                                        \
+            if (!value.is_string())                                  \
+                return false;                                        \
+            if (value.as_string() == "Fill") {                       \
+                setter(GUI::SizePolicy::Fill);                       \
+                return true;                                         \
+            }                                                        \
+            if (value.as_string() == "Fixed") {                      \
+                setter(GUI::SizePolicy::Fixed);                      \
+                return true;                                         \
+            }                                                        \
+            return false;                                            \
+        });
 }
diff --git a/Libraries/LibCore/Property.cpp b/Libraries/LibCore/Property.cpp
new file mode 100644
index 0000000000..8c6c2587c6
--- /dev/null
+++ b/Libraries/LibCore/Property.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <LibCore/Property.h>
+
+namespace Core {
+
+Property::Property(String name, Function<JsonValue()> getter, Function<bool(const JsonValue&)> setter)
+    : m_name(move(name))
+    , m_getter(move(getter))
+    , m_setter(move(setter))
+{
+}
+
+Property::~Property()
+{
+}
+
+}
diff --git a/Libraries/LibCore/Property.h b/Libraries/LibCore/Property.h
new file mode 100644
index 0000000000..baf9e0812c
--- /dev/null
+++ b/Libraries/LibCore/Property.h
@@ -0,0 +1,58 @@
+/*
+ * Copyright (c) 2020, Andreas Kling <kling@serenityos.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice, this
+ *    list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#pragma once
+
+#include <AK/Function.h>
+#include <AK/JsonValue.h>
+
+namespace Core {
+
+class Property {
+    AK_MAKE_NONCOPYABLE(Property);
+
+public:
+    Property(String name, Function<JsonValue()> getter, Function<bool(const JsonValue&)> setter = nullptr);
+    ~Property();
+
+    bool set(const JsonValue& value)
+    {
+        if (!m_setter)
+            return false;
+        return m_setter(value);
+    }
+
+    JsonValue get() const { return m_getter(); }
+
+    const String& name() const { return m_name; }
+
+private:
+    String m_name;
+    Function<JsonValue()> m_getter;
+    Function<bool(const JsonValue&)> m_setter;
+};
+
+}