spidermonkey note

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/* spidermonkey 3 basic element
1.runtime
2.context
3.global object
*/

/*
	usefull apis
    1.获取参数: jsval *argv = JS_ARGV(cx, vp);
	2.获得调用该方法的对象object：JSObject*obj = JS_THIS_OBJECT(cx,vp); 
    3.设置私有数据
    	3.1 JS_SetPrivate(jsObj,void*) 
        	reqiure JSClass.flags 存在 ‘JSCLASS_HAS_PRIVATE‘
        3.2 void JS_SetReservedSlot(JSObject *obj, uint32_t index, jsval v);
        	要求 JSClass.flags has ‘JSCLASS_HAS_RESERVED_SLOTS(n)‘
    4. 	用于回调js代码里函数：
    	JS_CallFunctionValue
    	JS_CallFunction
        JS_CallFunctionValue */

可以通过3.中的方法，将js对应的对象和方法保存起来，通过C代码回调（4中的函数）来调用js代码。

// 下面的代码将js对象和对象的方法通过JS_SetReservedSlot()保存起来

static void addCallBackAndThis(JSObject *obj, jsval callback, jsval &thisObj)
{
    if(callback != JSVAL_VOID) {
        ScriptingCore::getInstance()->setReservedSpot(0, obj, callback);
    }
    if(thisObj != JSVAL_VOID) {
        ScriptingCore::getInstance()->setReservedSpot(1, obj, thisObj);
    }
}

JSBool ScriptingCore::setReservedSpot(uint32_t i, JSObject *obj, jsval value) {
    JS_SetReservedSlot(obj, i, value);
    return JS_TRUE;
}

// 下面则通过JS_CallFunctionXXX 系列函数产生js的回调。

int ScriptingCore::handleMenuClickedEvent(void* data)
{
    if (NULL == data)
        return 0;
                                                           
    BasicScriptData* basicScriptData = static_cast<BasicScriptData*>(data);
    if (NULL == basicScriptData->nativeObject)
        return 0;
                                                           
    MenuItem* menuItem = static_cast<MenuItem*>(basicScriptData->nativeObject);
                                                           
    js_proxy_t * p = jsb_get_native_proxy(menuItem);
    if (!p) return 0;
    jsval retval;
    jsval dataVal;
    js_proxy_t *proxy = jsb_get_native_proxy(menuItem);
    dataVal = (proxy ? OBJECT_TO_JSVAL(proxy->obj) : JSVAL_NULL);
    executeJSFunctionFromReservedSpot(this->_cx, p->obj, dataVal, retval);
    return 1;
}

static void executeJSFunctionFromReservedSpot(JSContext *cx, JSObject *obj,
                                              jsval &dataVal, jsval &retval) {
    jsval func = JS_GetReservedSlot(obj, 0);
    if (func == JSVAL_VOID) { return; }
    jsval thisObj = JS_GetReservedSlot(obj, 1);
    JSAutoCompartment ac(cx, obj);
                       
    if (thisObj == JSVAL_VOID) {
        JS_CallFunctionValue(cx, obj, func, 1, &dataVal, &retval);
    } else {
        assert(!JSVAL_IS_PRIMITIVE(thisObj));
        JS_CallFunctionValue(cx, JSVAL_TO_OBJECT(thisObj), func, 1, &dataVal, &retval);
    }
}

spidermonkey note

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原文地址：http://my.oschina.net/lyr/blog/382693