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1 : /* Copyright (C) 2023 Wildfire Games.
2 : * This file is part of 0 A.D.
3 : *
4 : * 0 A.D. is free software: you can redistribute it and/or modify
5 : * it under the terms of the GNU General Public License as published by
6 : * the Free Software Foundation, either version 2 of the License, or
7 : * (at your option) any later version.
8 : *
9 : * 0 A.D. is distributed in the hope that it will be useful,
10 : * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 : * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 : * GNU General Public License for more details.
13 : *
14 : * You should have received a copy of the GNU General Public License
15 : * along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
16 : */
17 :
18 : #ifndef INCLUDED_JSI_GUIPROXY
19 : #define INCLUDED_JSI_GUIPROXY
20 :
21 : #include "gui/ObjectBases/IGUIObject.h"
22 : #include "scriptinterface/ScriptExtraHeaders.h"
23 :
24 : #include <memory>
25 : #include <utility>
26 :
27 : class ScriptInterface;
28 : class ScriptRequest;
29 :
30 : template <typename T>
31 : class JSI_GUIProxy;
32 :
33 : // See JSI_GuiProxy below
34 : #if GCC_VERSION
35 : # pragma GCC diagnostic push
36 : # pragma GCC diagnostic ignored "-Wnon-virtual-dtor"
37 : #elif MSC_VERSION
38 : # pragma warning(push, 1)
39 : # pragma warning(disable: 4265)
40 : #endif
41 :
42 : /**
43 : * JS GUI proxies need to store some private data.
44 : * This class is responsible for deleting that data.
45 : */
46 4 : class IGUIProxyObject final
47 : {
48 : template<typename T>
49 : friend class JSI_GUIProxy;
50 : friend std::unique_ptr<IGUIProxyObject> std::make_unique<IGUIProxyObject>();
51 : public:
52 9 : JSObject* Get() const
53 : {
54 9 : return m_Object.get();
55 : }
56 :
57 : using PrivateData = IGUIObject*;
58 :
59 : template<typename T>
60 0 : static T* FromPrivateSlot(JSObject* obj)
61 : {
62 0 : return static_cast<T*>(FromPrivateSlot<IGUIObject>(obj));
63 : }
64 : protected:
65 : template<typename T>
66 9 : static T* UnsafeFromPrivateSlot(JSObject* obj)
67 : {
68 9 : return static_cast<T*>(static_cast<PrivateData>(js::GetProxyPrivate(obj).toPrivate()));
69 : }
70 :
71 4 : IGUIProxyObject() = default;
72 : IGUIProxyObject(const IGUIProxyObject&) = delete;
73 : IGUIProxyObject(IGUIProxyObject&&) = delete;
74 :
75 : JS::PersistentRootedObject m_Object;
76 : PrivateData m_Ptr;
77 : };
78 : // Declare the IGUIObject* specialization - it's defined in _impl.h
79 : template<> IGUIObject* IGUIProxyObject::FromPrivateSlot<IGUIObject>(JSObject*);
80 :
81 : /**
82 : * Proxies need to store some data whose lifetime is tied to an interface.
83 : * This is the virtual interface of that data.
84 : */
85 30 : class GUIProxyProps
86 : {
87 : public:
88 30 : virtual ~GUIProxyProps() {};
89 :
90 : // @return true if @param name exists in this cache.
91 : virtual bool has(const std::string& name) const = 0;
92 : // @return the JSFunction matching @param name. Must call has() first as it can assume existence.
93 : virtual JSObject* get(const std::string& name) const = 0;
94 : virtual bool setFunction(const ScriptRequest& rq, const std::string& name, JSFunction* function) = 0;
95 : };
96 :
97 : /**
98 : * Handles the js interface with C++ GUI objects.
99 : * Proxy handlers must live for at least as long as the JS runtime
100 : * where a proxy object with that handler was created. The reason is that
101 : * proxy handlers are called during GC, such as on runtime destruction.
102 : * In practical terms, this means "just keep them static and store no data".
103 : *
104 : * GUI Objects only exist in C++ and have no JS-only properties.
105 : * As such, there is no "target" JS object that this proxy could point to,
106 : * and thus we should inherit from BaseProxyHandler and not js::Wrapper.
107 : *
108 : * Proxies can be used with prototypes and almost treated like regular JS objects.
109 : * However, the default implementation embarks a lot of code that we don't really need here,
110 : * since the only fanciness is that we cache JSFunction* properties.
111 : * As such, these GUI proxies don't have one and instead override get/set directly.
112 : *
113 : * To add a new JSI_GUIProxy, you'll need to:
114 : * - overload CreateJSObject in your class header.
115 : * - change the CGUI::AddObjectTypes method.
116 : * - explicitly instantiate the template & CreateJSObject via DECLARE_GUIPROXY.
117 : *
118 : */
119 : template<typename GUIObjectType>
120 : class JSI_GUIProxy : public js::BaseProxyHandler
121 : {
122 : // Need to friend other specializations so CreateFunctions() can call the IGUIObject version in all codepaths.
123 : template<typename T>
124 : friend class JSI_GUIProxy;
125 : public:
126 : // For convenience, this is the single instantiated JSI_GUIProxy.
127 : static JSI_GUIProxy& Singleton();
128 :
129 : // Call this in CGUI::AddObjectTypes.
130 : static std::pair<const js::BaseProxyHandler*, GUIProxyProps*> CreateData(ScriptInterface& scriptInterface);
131 :
132 : // Create the JS object, the proxy, the data and wrap it in a convenient unique_ptr.
133 : static std::unique_ptr<IGUIProxyObject> CreateJSObject(const ScriptRequest& rq, GUIObjectType* ptr, GUIProxyProps* data);
134 : protected:
135 : // @param family can't be nullptr because that's used for some DOM object and it crashes.
136 5 : JSI_GUIProxy() : BaseProxyHandler(this, false, false) {};
137 :
138 : // Note: SM provides no virtual destructor for baseProxyHandler.
139 : // This also enforces making proxy handlers dataless static variables.
140 5 : ~JSI_GUIProxy() {};
141 :
142 : static GUIObjectType* FromPrivateSlot(const ScriptRequest&, JS::CallArgs& args);
143 :
144 : // The default implementations need to know the type of the GUIProxyProps for this proxy type.
145 : // This is done by specializing this struct's alias type.
146 : struct PropCache;
147 :
148 : // Specialize this to define the custom properties of this type.
149 : static void CreateFunctions(const ScriptRequest& rq, GUIProxyProps* cache);
150 :
151 : // Convenience helper for the above.
152 : template<auto callable>
153 : static void CreateFunction(const ScriptRequest& rq, GUIProxyProps* cache, const std::string& name);
154 :
155 : // This handles returning custom properties. Specialize this if needed.
156 : bool PropGetter(JS::HandleObject proxy, const std::string& propName, JS::MutableHandleValue vp) const;
157 : protected:
158 : // BaseProxyHandler interface below
159 :
160 : // Handler for `object.x`
161 : virtual bool get(JSContext* cx, JS::HandleObject proxy, JS::HandleValue receiver, JS::HandleId id, JS::MutableHandleValue vp) const override final;
162 : // Handler for `object.x = y;`
163 : virtual bool set(JSContext* cx, JS::HandleObject proxy, JS::HandleId id, JS::HandleValue vp,
164 : JS::HandleValue receiver, JS::ObjectOpResult& result) const final;
165 : // Handler for `delete object.x;`
166 : virtual bool delete_(JSContext* cx, JS::HandleObject proxy, JS::HandleId id, JS::ObjectOpResult& result) const override final;
167 :
168 : // The following methods are not provided by BaseProxyHandler.
169 : // We provide defaults that do nothing (some raise JS exceptions).
170 :
171 : // The JS code will see undefined when querying a property descriptor.
172 0 : virtual bool getOwnPropertyDescriptor(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::HandleId UNUSED(id),
173 : JS::MutableHandle<mozilla::Maybe<JS::PropertyDescriptor>> UNUSED(desc)) const override
174 : {
175 0 : return true;
176 : }
177 : // Throw an exception is JS code attempts defining a property.
178 0 : virtual bool defineProperty(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::HandleId UNUSED(id),
179 : JS::Handle<JS::PropertyDescriptor> UNUSED(desc), JS::ObjectOpResult& UNUSED(result)) const override
180 : {
181 0 : return false;
182 : }
183 : // No accessible properties.
184 0 : virtual bool ownPropertyKeys(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::MutableHandleIdVector UNUSED(props)) const override
185 : {
186 0 : return true;
187 : }
188 : // Nothing to enumerate.
189 0 : virtual bool enumerate(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::MutableHandleIdVector UNUSED(props)) const override
190 : {
191 0 : return true;
192 : }
193 : // Throw an exception is JS attempts to query the prototype.
194 0 : virtual bool getPrototypeIfOrdinary(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), bool* UNUSED(isOrdinary), JS::MutableHandleObject UNUSED(protop)) const override
195 : {
196 0 : return false;
197 : }
198 : // Throw an exception - no prototype to set.
199 0 : virtual bool setImmutablePrototype(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), bool* UNUSED(succeeded)) const override
200 : {
201 0 : return false;
202 : }
203 : // We are not extensible.
204 0 : virtual bool preventExtensions(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), JS::ObjectOpResult& UNUSED(result)) const override
205 : {
206 0 : return true;
207 : }
208 0 : virtual bool isExtensible(JSContext* UNUSED(cx), JS::HandleObject UNUSED(proxy), bool* extensible) const override
209 : {
210 0 : *extensible = false;
211 0 : return true;
212 : }
213 : };
214 :
215 : #if GCC_VERSION
216 : # pragma GCC diagnostic pop
217 : #elif MSC_VERSION
218 : # pragma warning(pop)
219 : #endif
220 :
221 :
222 : #endif // INCLUDED_JSI_GUIPROXY
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