[领域]Javascript Hacking Guide 系列文章（2007-2-7更新到part6）

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2007-02 ( 6)
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JavaScript 领域模型 prototype F#Ruby

那天听东东将javascript，他讲得也匆忙，我听得也犯晕，心想如果能够建立起javascript的内存对象模型该多好啊。可是在网上找了好久，也没有发现javascript的Hacking guide，不经意间，却找到了ruby hacking guide，不错不错。还好有mozilla 中蜘蛛猴的源代码，我想离真正建立javascript的对象模型（内存模型）已经不远了。

仿照ruby hacking guide的做法，先把已经掌握的资料用图表示出来，关于其之间的详细的关系，我会在后面的文章中举例说明。

图示说明：椭圆边框的部分是c的结构体（struct），带圆点的线条代表指针，在椭圆外的是该结构体所在的文件。

这算javascript内存模型的第一部分吧。老是等研究完了再写，恐怕就没有激情了。呵呵

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[领域] JavaScript Hacking Guide part2 | [个人]加入了ruby hacking guide的中文翻 ...

2007-02-06 17:41
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10 楼 sunshineormer 2007-02-07

书接上回，我们说到global对象的初始创建已经完成了。那，你肯定会问了，为什么说是初始创建，而不是完整的创建呢？要回答这个问题，还要从ECMA262说起：
<o:p> </o:p>
在ECMA262，强调了Global这个全局函数的很多信息，比如说，这个内置对象是先于Context就存在了的。比方说，在默认的情况下，我们调用的方法，其实都是Global这个对象的方法。比方说 ：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>var obj = new Object();
</div>
其实也就等于
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>var obj = new this.Object();
</div>
像parseInt这样的方法，其实也都是挂在Global名下的。Global对象下，有若干属性，包括Object,Array,Boolean,String…. 这么说你肯定就明白了。其他的内置对象，都是Global的一个属性值。其实，不光内置对象，所有的新定义的function ，也都会在定义后（即通过function关键字）在Global的属性列表中增加一个指向自己的属性。
那么，我们可以想一下，Global和Object之间的关系，真的是很微妙啊。Global.prototype和Object.prototype会是什么样的关系呢？
如果你是一个心急的人，一点会说：“写一段代码不就知道了吗？”。你的程序是不是这样写的？
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>document.writeln(global.prototype = = …
</div>
sorry,忘了告诉你了，global对象是不能这么访问的。你在程序中写：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>document.writeln(global);
</div>
将会打出undefined.不过，这个Global对象又缺省存在，我们应该怎么去访问它呢？请让我先卖一个关子吧。
<o:p> </o:p>
有了Global的这个概念以后，我们继续来分析源代码。从part4－part5，我们基本上只在围绕着一个函数做文章，
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>glob = JS_NewObject(cx, &global_class, NULL, NULL);
</div>
这个函数的调用关系讲完之后，我们就要看下面的代码段了。
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>JS_InitStandardClasses(cx, glob)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>JS_DefineFunctions(cx, glob, shell_functions)
</div>
从名字上看，我们是要在glob这个对象下，创建并挂接系统内置的对象了（事实也果真如此）。
<o:p> </o:p>
JS_InitStandardClasses这个函数定义在jsapi.c 这个文件中，我们可以很容易的找到其中的重要部分：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/* Define a top-level property 'undefined' with the undefined value. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> atom = cx->runtime->atomState.typeAtoms[JSTYPE_VOID];
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!OBJ_DEFINE_PROPERTY(cx, obj, ATOM_TO_JSID(atom), JSVAL_VOID,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> NULL, NULL, JSPROP_PERMANENT, NULL)) {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return JS_FALSE;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> }
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Function and Object require cooperative bootstrapping magic. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!js_InitFunctionAndObjectClasses(cx, obj))
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return JS_FALSE;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Initialize the rest of the standard objects and functions. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return js_InitArrayClass(cx, obj) &&<o:p></o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_InitBlockClass(cx, obj) &&<o:p></o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_InitBooleanClass(cx, obj) &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_InitCallClass(cx, obj) &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_InitExceptionClasses(cx, obj) &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_InitMathClass(cx, obj) &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> 。。。。
</div>
我在这段代码中，找到的几个处比较重要的函数调用，用红颜色圈了出来。
第一个部分是一个宏：OBJ_DEFINE_PROPERTY，这个宏的主要作用是调用函数指针，来给glob对象创建一个新的属性，属性的类型是JSVAL_VOID,这说明，ECMA262中要求的，Undefined属性是Global的一个属性，已经得到了实现。
第二部分，是我们的主角，弄懂了这个函数，基本上就可以初步理解ECMAScript的对象模型了。而且，它的注释也很有意思，使用了cooperative bootstrapping magic这样的字眼。好的，那就让我们跑到后台去，看看魔术师的鬼把戏是怎么出来的吧。
<o:p> </o:p>
js_InitFunctionAndObjectClasses仍然在同文件中，所以不用调转就可以找到。
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/* If cx has no global object, use obj so prototypes can be found. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!cx->globalObject)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JS_SetGlobalObject(cx, obj);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Record Function and Object in cx->resolvingTable, if we are resolving. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>。。。。
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/* Initialize the function class first so constructors can be made. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> fun_proto = js_InitFunctionClass(cx, obj);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!fun_proto)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> goto out;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Initialize the object class next so Object.prototype works. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> obj_proto = js_InitObjectClass(cx, obj);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!obj_proto) {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> fun_proto = NULL;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> goto out;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> }
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Function.prototype and the global object delegate to Object.prototype. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> OBJ_SET_PROTO(cx, fun_proto, obj_proto);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!OBJ_GET_PROTO(cx, obj))
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> OBJ_SET_PROTO(cx, obj, obj_proto);
</div>
这个程序的开头两大段，做的工作，我猜想我们可以跳过，不知道正不正确，我更想从js_InitFunctionClass(cx, obj)开始（标红的部分）。我们可以看到，我们还是把global当成参数传到了这个函数体中，这样，我们得到的的返回值，就是Function.prototype;同样，如果我们继续向下看，就会看到js_InitObjectClass(cx, obj)这个函数，从返回值、注释加上对函数名的推测，我们会看到，函数运行后返回了Object.prototype。
然后呢，我们留意一下注释，哦，我的老天啊。我的猜测是没有错的Function.prototype和Global对象的prototype被委托给了Object.prototype.这还不够让我们兴奋的吗？
<o:p> </o:p>
允许兴奋，可不要兴奋大发劲了啊。我们还有正事没有做呢。js_InitFunctionClass还在等着我们去解密呢。
这个函数在jsfun.c中有定义，麻烦你动手先将它找出来。
<o:p> </o:p>
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>JSObject *
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>js_InitFunctionClass(JSContext *cx, JSObject *obj)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>{
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSObject *proto;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSAtom *atom;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSFunction *fun;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> proto = JS_InitClass(cx, obj, NULL, &js_FunctionClass, Function, 1,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> function_props, function_methods, NULL, NULL);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!proto)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return NULL;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> atom = js_Atomize(cx, js_FunctionClass.name, strlen(js_FunctionClass.name),
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> 0);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!atom)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> goto bad;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> fun = js_NewFunction(cx, proto, NULL, 0, 0, obj, NULL);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!fun)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> goto bad;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> fun->u.i.script = js_NewScript(cx, 1, 0, 0);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!fun->u.i.script)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> goto bad;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> fun->u.i.script->code[0] = JSOP_STOP;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> fun->flags |= JSFUN_INTERPRETED;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; text-indent: 21pt; padding-top: 0cm; border-bottom: medium none;'>return proto;
</div>
<o:p> </o:p>
为了简单起见，我将这个函数的调用图先列出来：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>js_InitFunctionClass
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JS_InitClass
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_Atomize
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_NewObject
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_NewGCThing
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_Atomize
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_NewFunction
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_NewGCThing
</div>
<o:p> </o:p>
那么，我们可以从这个调用图中推导出什么来呢？咱们下回书接着说。

9 楼 sp42 2007-02-06

系统地建立JS知识和对其原理的理解，这是一个图文并茂的好材料

8 楼 sunshineormer 2007-02-06

typeof Function ＝＝ function。（图中灰的表示typeof的返回值是function）

7 楼 jianfeng008cn 2007-02-06

typeof function ==object?

很好的文章，让不懂c系列的我感觉很有收获，回头再好好学学c系列的语言。

6 楼 sunshineormer 2007-02-06

预告内容：在接下来的文章中，将对global全局对象进行详细讲解，并给大家分析创建函数的过程。根据这部分内容，将对前面的图片进行部分的修改。

5 楼 sunshineormer 2007-02-06

part5：
map是JSObject的一个重要属性，存放一个对象的所有的属性的入口。要想了解map，就需要打开jsobj.h文件，看里面的定义。
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>struct JSObject {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSObjectMap *map;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> jsval *slots;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>};
</div>
<o:p> </o:p>
很自然的，我们还要找到JSObjectMap的定义，它也在jsobj.h文件中
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>struct JSObjectMap {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> jsrefcount nrefs; /* count of all referencing objects */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSObjectOps *ops; /* high level object operation vtable */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> uint32 nslots; /* length of obj->slots vector */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> uint32 freeslot; /* index of next free obj->slots element */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>};
</div>
在这个定义中，最重要的信息隐含在注释中，第一个是对ops的注释，我们会看到ops其实是一个virtual table。这表示，对象的所有的属性名，都存放在这个vtable中；第2个信息是对nslots的注释，它提及obj->slots其实是一个vector。
这如同在告诉我们，我们在定义一个对象的属性时，属性的名称和类型等信息，会通过ops增加到属性表中，属性的值会对应放到slots这个vector中。例如：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>var obj = new Object();
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>obj.a = 5;
</div>
 那么“a”这个属性的类型是整型的，slots中增加了个新的值5。仔细看去，ops是JSObjectOps这个结构体中，我们可以在jsapi.h中找到这个结构体的定义：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>struct JSObjectOps {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Mandatory non-null function pointer members. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSNewObjectMapOp newObjectMap;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSObjectMapOp destroyObjectMap;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSLookupPropOp lookupProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSDefinePropOp defineProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyIdOp getProperty;<o:p></o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyIdOp setProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSAttributesOp getAttributes;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSAttributesOp setAttributes;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyIdOp deleteProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSConvertOp defaultValue;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSNewEnumerateOp enumerate;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSCheckAccessIdOp checkAccess;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Optionally non-null members start here. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSObjectOp thisObject;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyRefOp dropProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSNative call;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSNative construct;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSXDRObjectOp xdrObject;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSHasInstanceOp hasInstance;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSSetObjectSlotOp setProto;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSSetObjectSlotOp setParent;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSMarkOp mark;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSFinalizeOp clear;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSGetRequiredSlotOp getRequiredSlot;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSSetRequiredSlotOp setRequiredSlot;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>};
</div>
<o:p> </o:p>
我们可以简单的浏览一下其中的函数指针名称，创建object的map，定义属性，删除属性，给属性设置值或者获取属性值。。。。闭上眼睛想一想，这其中的函数指针是如此之多，所以一个对象的属性的类型判断（比如是整型还是String还是其他的）或者是属性名或者属性值的存放，都是通过预先定义好的指针函数来完成。
我们甚至可以用一个新的示意图来表示这一切：
<o:p> <img src='http://sunshineormer.blogdriver.com/sunshineormer/inc/ECMAScript5.jpg' alt=''/></o:p>
<v:shapetype id="_x0000_t75" stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape id="_x0000_i1025" style="WIDTH: 213.75pt; HEIGHT: 131.25pt" type="#_x0000_t75"><v:imagedata o:title="" src="file:///C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image001.png"></v:imagedata></v:shape>
我们可以这样去想，有一个table，里面存放对象的属性列表。根据ruby hacking guide的说法，我们可以想像，有一张大的表，存放所有的对象的属性，也可能每个对象有自己的属性表。但，这属于具体实现的范畴，我们只要明白每个对象有属于自己的属性表，对表格中的行或者列进行操作时，是由JSObjectOps这个结构体中的指针函数来完成的就可以了。
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/*
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * Share proto's map only if it has the same JSObjectOps, and only if
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * proto's class has the same private and reserved slots as obj's map
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * and class have. We assume that if prototype and object are of the
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * same class, they always have the same number of computed reserved
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * slots (returned via clasp->reserveSlots); otherwise, prototype and
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * object classes must have the same (null or not) reserveSlots hook.
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (proto &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> (map = proto->map)->ops == ops &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> ((protoclasp = OBJ_GET_CLASS(cx, proto)) == clasp ||
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> (!((protoclasp->flags ^ clasp->flags) &
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> (JSCLASS_HAS_PRIVATE |
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> (JSCLASS_RESERVED_SLOTS_MASK << JSCLASS_RESERVED_SLOTS_SHIFT))) &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> protoclasp->reserveSlots == clasp->reserveSlots)))
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /*
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * Default parent to the parent of the prototype, which was set from
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * the parent of the prototype's constructor.
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!parent)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> parent = OBJ_GET_PARENT(cx, proto);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Share the given prototype's map. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> obj->map = js_HoldObjectMap(cx, map);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Ensure that obj starts with the minimum slots for clasp. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> nslots = JS_INITIAL_NSLOTS;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> } else {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Leave parent alone. Allocate a new map for obj. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> map = ops->newObjectMap(cx, 1, ops, clasp, obj);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!map)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> goto bad;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> obj->map = map;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Let ops->newObjectMap set nslots so as to reserve slots. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> nslots = map->nslots;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> }
</div>
Ok，我们在上回书说到有若干的判断条件，就是为了创建一个map，并设置为obj->map的属性――不管是用parent的原型来创建，还是单独创建新的map（if 。。。else 部分），最终都是为了这个目的。
<o:p> </o:p>
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/* Allocate a slots vector, with a -1'st element telling its length. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> newslots = AllocSlots(cx, NULL, nslots);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!newslots) {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> js_DropObjectMap(cx, obj->map, obj);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> obj->map = NULL;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> goto bad;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> }
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Set the proto, parent, and class properties. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> newslots[JSSLOT_PROTO] = OBJECT_TO_JSVAL(proto);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> newslots[JSSLOT_PARENT] = OBJECT_TO_JSVAL(parent);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> newslots[JSSLOT_CLASS] = PRIVATE_TO_JSVAL(clasp);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Clear above JSSLOT_CLASS so the GC doesn't load uninitialized memory. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> for (i = JSSLOT_CLASS + 1; i < nslots; i++)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> newslots[i] = JSVAL_VOID;
</div>

4 楼 sunshineormer 2007-02-06

part4 ：
在正式开始之前，先说点关于RHG的话题，我的JHG系列，基本是在仿照着RHG的风格在写作。RHG的述事风格很有条理性，并且会指导你跳过跳过再跳过一些无关痛痒的程序片段。这是对的，在一大堆程序中，能够快速准确的定位，不是件很容易的事情。
从今天开始，我将讲述我对蜘蛛猴源代码的查找过程：
在js.c 找到main里面的调用过程，注意，下面的函数都是精简过的，而且是平级的关系：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>rt = JS_NewRuntime(...
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>cx = JS_NewContext(rt,...
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>glob = JS_NewObject(cx, &global_class, NULL, NULL);
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>JS_InitStandardClasses(cx, glob)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>JS_DefineFunctions(cx, glob, shell_functions)
</div>
<o:p> </o:p>
ok,现在来看一下，运行时和上下文环境是解释引擎的初始化，可以先跳过，哈，我们真正关心的肯定是从glob开始的那3句了：glob是ECMA262中要求的内置全局对象，这里有我们比较感兴趣的NewObject方法;紧接其后的，将是对其他内置对象的创建过程（JS_InitStandardClasses）;最后，我们可以看看全局对象global都有哪些方法。
<o:p> </o:p>
JS_NewObject的函数声明，被定义在jsobj.h中，函数定义在jsobj.c中：
：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>extern JSObject *
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>js_NewObject(JSContext *cx, JSClass *clasp, JSObject *proto, JSObject *parent);
</div>
记住，因为是要初始化glob对象，我们在传递参数是，proto和parent都传递了NULL。这样，有效传递到函数体中的，就只有刚刚创建的上下文环境（cx）和clasp了。clasp的值被赋予了global_class,这是个全局变量，定义在js.c中
<o:p> </o:p>
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>JSClass global_class = {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> "global", JSCLASS_NEW_RESOLVE | JSCLASS_GLOBAL_FLAGS,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JS_PropertyStub, JS_PropertyStub,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JS_PropertyStub, JS_PropertyStub,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> global_enumerate, (JSResolveOp) global_resolve,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JS_ConvertStub, JS_FinalizeStub,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSCLASS_NO_OPTIONAL_MEMBERS
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>};
</div>
<o:p> </o:p>
在这个变量中，我们发现了“global”这个单词，结合JSClass这名字，再根据MFC等框架的经验，很容易的我们就可以联想到，这是用来做动态生成和RTTI的类名。
要想看懂这个结构体，一点也不难，只需到jsapi.h中找JSClass的定义即可。里面也没有什么太多的玩意，只是有一堆的函数指针，我们只需简单留言其中的强制非空部分即可。
<o:p> </o:p>
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>struct JSClass {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> const char *name;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> uint32 flags;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Mandatory non-null function pointer members. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyOp addProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyOp delProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyOp getProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSPropertyOp setProperty;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSEnumerateOp enumerate;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSResolveOp resolve;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSConvertOp convert;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSFinalizeOp finalize;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'><o:p> </o:p>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> /* Optionally non-null members start here. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSGetObjectOps getObjectOps;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSCheckAccessOp checkAccess;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSNative call;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSNative construct;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSXDRObjectOp xdrObject;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSHasInstanceOp hasInstance;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSMarkOp mark;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> JSReserveSlotsOp reserveSlots;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>};
</div>
放眼望去，偶的老天，原来类的属性操作（增加属性，删除属性，查询和设置属性都是在这定义的啊）。要知道，在javascript中，所有的attributes和方法都是属性啊。按下不表。
还是跳回到newObject
<o:p> </o:p>
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/* Bootstrap the ur-object, and make it the default prototype object. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!proto) {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!js_GetClassId(cx, clasp, &id))
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return NULL;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!js_GetClassPrototype(cx, parent, id, &proto))
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return NULL;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!proto &&
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> !js_GetClassPrototype(cx, parent, INT_TO_JSID(JSProto_Object),
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> &proto)) {
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return NULL;
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> }
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> }
</div>
先看这段代码，简而言之，想做的事情是，找到要创建对象的原型，如果实在找不到，就使用缺省的原型对象。跳过。
接下来的代码，
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/* Always call the class's getObjectOps hook if it has one. */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> ops = clasp->getObjectOps
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> ? clasp->getObjectOps(cx, clasp)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> : &js_ObjectOps;
</div>
只是想找一个对象的操作方法集，因为我们在定义global_class全局对象时，使用了JSCLASS_NO_OPTIONAL_MEMBERS宏，可以很轻松的判定这个表达式如同：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>ops = &js_ObjectOps;
</div>
<o:p> </o:p>
继续向后：
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>/*
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * Allocate a zeroed object from the GC heap. Do this *after* any other
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * GC-thing allocations under js_GetClassPrototype or clasp->getObjectOps,
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> * to avoid displacing the newborn root for obj.
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> */
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> obj = (JSObject *) js_NewGCThing(cx, GCX_OBJECT, sizeof(JSObject));
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> if (!obj)
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'> return NULL;
</div>
从注释中，我们可以轻松的看出，按照ECMAScript的说法，对象被分配到heap中，已经得到了实现了。
被定义在了jsgc.c中，我们不想太多的去看堆的alloc分配，只要知道这里生成了一个空的JSObject对象即可。
<div style='padding-right: 4pt; padding-left: 4pt; background: silver; padding-bottom: 1pt; padding-top: 1pt;'>
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>void *
<p class='MsoNormal' style='border-right: medium none; padding-right: 0cm; border-top: medium none; padding-left: 0cm; background: silver; padding-bottom: 0cm; margin: 0cm 0cm 0pt; border-left: medium none; padding-top: 0cm; border-bottom: medium none;'>js_NewGCThing(JSContext *cx, uintN flags, size_t nbytes)
</div>
再接着，是一大段的判断条件，想法很简单，既而是已经在heap中创建了对象，就要给对象的map和slot进行赋值了：一种做法是判断了若干条件后，用原型的map；另一种可能，是创建新的map。
<o:p> </o:p>
你会问map里面都存放了什么？呵呵。好问题。且听下回分解吧。

3 楼 sunshineormer 2007-02-06

part2：
感谢超德和梁健，你们是我前进的动力。
<img src='http://sunshineormer.blogdriver.com/sunshineormer/inc/ECMAScript2.jpg' align='baseline' alt=' '/>
昨天贴出来的，只能算是初步的编程模型，如果想弄清楚javascript的内存模型，必须看这幅图，不过这幅图还有一些简化的部分。以后会用程序来验证和说明这幅图的正确性，敬请期待。
 part3：
跟东、雪和健讨论后，重新修改了图2,可以联系图1来思考它们之间的演进关系了。
<img src='http://sunshineormer.blogdriver.com/sunshineormer/inc/ECMAScript3.jpg' align='baseline' alt=' '/>
这个周末，基本上是跟指针，对象一起度过的。即使是在我偶而为之的睡梦中，也是在思考函数指针和指针函数。呵呵。
周日整理出来的继承（原型）链图，可以说是javascript对象基础中比较深的部分了。
<img src='http://sunshineormer.blogdriver.com/sunshineormer/inc/ECMAScript4.jpg' align='baseline' alt=' '/>
浅蓝色的，typeof（）＝＝Object，灰色的部分，typeof ＝＝ Function。这里面只有FunctionPrototype出乎我的意料，我对它的期望值是浅蓝色，可是，运行程序的结果证明，它是灰色调的。

2 楼 sunshineormer 2007-02-06

sorry,我写blog写惯了，喜欢一段一段的写。马上改正。

1 楼 ITeye管理员 2007-02-06

请将这一系列的文章发在同一topic下，谢谢。

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