JavaScript-C/C++ (SpiderMonkey) 引擎嵌入开发指南(中文向导)

SpiderMonkey的世界

运行时环境

上下文

全局对象

在C++中执行JavaScript脚本

第1步-创建JavaScript运行时环境(runtime)

JSRuntime*rt=JS_NewRuntime(1000000L);
if(rt==NULL)
{
//Dosomeerrorreporting
}

第2步-创建一个上下文(context)

JSContext*cx=JS_NewContext(m_rt,8192);
if(cx==NULL)
{
//Dosomeerrorreporting
}

第3步-初始化全局对象(globalobject)

JSClassglobalClass=
{
	"Global",0,
	JS_PropertyStub,JS_PropertyStub,
	JS_PropertyStub,JS_PropertyStub,
	JS_EnumerateStub,JS_ResolveStub,
	JS_ConvertStub,JS_FinalizeStub
};

JSObject*globalObj=JS_NewObject(cx,&globalClass,0,0);
JS_InitStandardClasses(cx,globalObj);

第4步-执行脚本

std::stringscript="vartoday=Date();today.toString();";
jsvalrval;
uintNlineno=0;
JSBoolok=JS_EvaluateScript(cx,globalObj,script.c_str(),
	script.length(),"script",lineno,&rval);

JSString*str=JS_ValueToString(cx,rval);
std::cout<<JS_GetStringBytes(str);

第5步-清理脚本引擎

JS_DestroyContext(cx);
JS_DestroyRuntime(rt);

在C++中定义JavaScript对象

classCustomer
{
public:
	intGetAge(){returnm_age;}
	voidSetAge(intnewAge){m_age=newAge;}
	std::stringGetName(){returnm_name;}
	voidSetName(std::stringnewName){m_name=newName;}
private:
	intm_age;
	std::stringm_name;
};

第1步-JavaScript对象

//JSCustomer.h

classJSCustomer
{
public:
	JSCustomer()
	:m_pCustomer(NULL){}
	~JSCustomer()
	{
	deletem_pCustomer;
	m_pCustomer=NULL;
	}
	staticJSClasscustomerClass;
protected:
	voidsetCustomer(Customer*customer){m_pCustomer=customer;}
	Customer*getCustomer(){returnm_pCustomer;}
private:
	Customer*m_pCustomer;
};

//JSCustomer.cpp

JSClassJSCustomer::customerClass=
{
	"Customer",
	JSCLASS_HAS_PRIVATE,
	JS_PropertyStub,
	JS_PropertyStub,
	JSCustomer::JSGetProperty,
	JSCustomer::JSSetProperty,
	JS_EnumerateStub,
	JS_ResolveStub,
	JS_ConvertStub,
	JSCustomer::JSDestructor
};

staticJSBoolJSGetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp);
staticJSBoolJSSetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp);
staticJSBoolJSConstructor(JSContext*cx,JSObject*obj,uintNargc,
	jsval*argv,jsval*rval);
staticvoidJSDestructor(JSContext*cx,JSObject*obj);

第2步-初始化JavaScript对象

staticJSObject*JSInit(JSContext*cx,JSObject*obj,JSObject*proto);

JSObject*JSCustomer::JSInit(JSContext*cx,JSObject*obj,JSObject*proto)
{
	JSObject*newObj=JS_InitClass(cx,obj,proto,&customerClass,
	JSCustomer::JSConstructor,0,
	JSCustomer::customer_properties,JSCustomer::customer_methods,
	NULL,NULL);
	returnnewObj;
}

JSBoolJSCustomer::JSConstructor(JSContext*cx,JSObject*obj,uintNargc,
	jsval*argv,jsval*rval)
{
	JSCustomer*p=newJSCustomer();

	p->setCustomer(newCustomer());
	if(!JS_SetPrivate(cx,obj,p))
	returnJS_FALSE;
	*rval=OBJECT_TO_JSVAL(obj);
	returnJS_TRUE;
}

voidJSCustomer::JSDestructor(JSContext*cx,JSObject*obj)
{
	JSCustomer*p=JS_GetPrivate(cx,obj);
	deletep;
	p=NULL;
}

第3步-增加属性

staticJSPropertySpeccustomer_properties[];
enum{name_prop,age_prop};

JSPropertySpecJSCustomer::customer_properties[]=
{
	{"name",name_prop,JSPROP_ENUMERATE},
	{"age",age_prop,JSPROP_ENUMERATE},
	{0}
};

JSBoolJSCustomer::JSGetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp)
{
	if(JSVAL_IS_INT(id))
	{
		Customer*priv=(Customer*)JS_GetPrivate(cx,obj);
		switch(JSVAL_TO_INT(id))
		{
		casename_prop:
			break;
		caseage_prop:
			*vp=INT_TO_JSVAL(priv->getCustomer()->GetAge());
			break;
		}
	}
	returnJS_TRUE;
}JSBoolJSCustomer::JSSetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp)
{
	if(JSVAL_IS_INT(id))
	{
		Customer*priv=(Customer*)JS_GetPrivate(cx,obj);
		switch(JSVAL_TO_INT(id))
		{
		casename_prop:
			break;
		caseage_prop:
			priv->getCustomer()->SetAge(JSVAL_TO_INT(*vp));
			break;
		}
	}
	returnJS_TRUE;
}

第4步-增加方法

staticJSFunctionSpeccustomer_methods[];

JSFunctionSpecwxJSFrame::wxFrame_methods[]=
{
	{"computeReduction",computeReduction,1,0,0},
	{0}
};

staticJSBoolcomputeReduction(JSContext*cx,JSObject*obj,uintNargc,
	jsval*argv,jsval*rval);

JSBoolJSCustomer::computeReduction(JSContext*cx,JSObject*obj,uintNargc,
	jsval*argv,jsval*rval)
{
	JSCustomer*p=JS_GetPrivate(cx,obj);
	if(p->getCustomer()->GetAge()<25)
		*rval=INT_TO_JSVAL(10);
	else
		*rval=INT_TO_JSVAL(5);
	returnJS_TRUE;
}

一个例子

varc=newCustomer();
c.name="Franky";
c.age=32;
varreduction=c.computeReduction();

JSObject*obj=JSCustomer::JSInit(cx,global);

代码

//main.cpp演示如何执行javascript

#defineXP_PC
#include<string>
#include<iostream>
#include<fstream>
#include<jsapi.h>
#include"JSCustomer.h"

JSClassglobalClass={
"Global",
0,
JS_PropertyStub,
JS_PropertyStub,
JS_PropertyStub,
JS_PropertyStub,
JS_EnumerateStub,
JS_ResolveStub,
JS_ConvertStub,
JS_FinalizeStub
};
voidmain(intargc,char*argv[])
{
if(argc<2)
{
std::cout<<"JSExecusage"<<std::endl
<<"------------"<<std::endl
<<"JSExec<fileName>"<<std::endl;
}
std::stringscript;
std::stringbuffer;
std::ifstreamistr(argv[1]);
if(istr.is_open())
{
do{
std::getline(istr,buffer);
script+=buffer;
}while(!istr.fail());
}
else
{
std::cout<<"JSExecerror"<<std::endl
<<"------------"<<std::endl
<<"Can'topenscriptfile"<<argv[1]<<std::endl;
exit(0);
}
JSRuntime*rt=JS_Init(1000000L);
if(rt)
{
JSContext*cx=JS_NewContext(rt,8192);
if(cx)
{
JSObject*globalObj=JS_NewObject(cx,&globalClass,0,0);
if(globalObj)
{
JS_InitStandardClasses(cx,globalObj);
//InitJSCustomer
JSCustomer::JSInit(cx,globalObj);
//Executethescript
jsvalrval;
uintNlineno=0;
JSString*str;
JSBoolok=JS_EvaluateScript(cx,globalObj,script.c_str(),
script.length(),argv[1],lineno,&rval);
if(ok==JS_TRUE)
{
str=JS_ValueToString(cx,rval);
char*s=JS_GetStringBytes(str);
std::cout<<"JSExecresult"<<std::endl
<<"-------------"<<std::endl
<<s<<std::endl;
}
else
{
std::cout<<"JSExecerror"<<std::endl
<<"------------"<<std::endl
<<"ErrorinJavaScriptfile"<<argv[1]<<std::endl;
}
}
else
{
std::cout<<"Unabletocreatetheglobalobject";
}
JS_DestroyContext(cx);
}
else
{
std::cout<<"Unabletocreateacontext";
}
JS_Finish(rt);
}
else
{
std::cout<<"UnabletoinitializetheJavaScriptEngine";
}
}

//JSCustomer.h演示CustomerJavaScript类的定义

/***JSCustomer.h-Exampleformytutorial:ScriptingC++withJavaScript
*(c)2002-FrankyBraem
*http://www.braem17.yucom.be*/
#ifndef_JSCustomer_H
#define_JSCustomer_H
#include"Customer.h"

classJSCustomer
{
public:
	/***Constructor*/
	JSCustomer()
	:m_pCustomer(NULL){}
	/***Destructor*/
	virtual~JSCustomer()
	{
	deletem_pCustomer;
	m_pCustomer=NULL;
	}
	/***JSGetProperty-Callbackforretrievingproperties*/
	staticJSBoolJSGetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp);
	/***JSSetProperty-Callbackforsettingproperties*/
	staticJSBoolJSSetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp);
	/***JSConstructor-CallbackforwhenawxCustomerobjectiscreated*/
	staticJSBoolJSConstructor(JSContext*cx,JSObject*obj,uintNargc,jsval*argv,jsval*rval);
	/***JSDestructor-CallbackforwhenawxCustomerobjectisdestroyed*/
	staticvoidJSDestructor(JSContext*cx,JSObject*obj);
	/***JSInit-CreateaprototypeforwxCustomer*/
	staticJSObject*JSInit(JSContext*cx,JSObject*obj,JSObject*proto=NULL);
	staticJSBoolcomputeReduction(JSContext*cx,JSObject*obj,uintNargc,jsval*argv,jsval*rval);
	staticJSClassCustomer_class;
	voidsetCustomer(Customer*customer){m_pCustomer=customer;}
	Customer*getCustomer(){returnm_pCustomer;}
private:
	Customer*m_pCustomer;
	staticJSPropertySpecCustomer_properties[];
	staticJSFunctionSpecCustomer_methods[];
	enum{name_prop,age_prop};
};
#endif//_JSCustomer_H

//JSCustomer.cpp演示JSCustomer类的实现

/***JSCustomer.cpp-Exampleformytutorial:ScriptingC++withJavaScript
*(c)2002-FrankyBraem
*http://www.braem17.yucom.be*/
#include<string>
#defineXP_PC
#include<jsapi.h>
//#include"Customer.h"
#include"JSCustomer.h"

JSPropertySpecJSCustomer::Customer_properties[]={
{"name",name_prop,JSPROP_ENUMERATE},
{"age",age_prop,JSPROP_ENUMERATE},
{0}
};
JSFunctionSpecJSCustomer::Customer_methods[]={
{"computeReduction",computeReduction,1,0,0},
{0,0,0,0,0}
};
JSClassJSCustomer::Customer_class={
"Customer",
JSCLASS_HAS_PRIVATE,
JS_PropertyStub,
JS_PropertyStub,
JSCustomer::JSGetProperty,
JSCustomer::JSSetProperty,
JS_EnumerateStub,
JS_ResolveStub,
JS_ConvertStub,
JSCustomer::JSDestructor
};
JSBoolJSCustomer::JSGetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp)
{
if(JSVAL_IS_INT(id))
{
JSCustomer*p=(JSCustomer*)JS_GetPrivate(cx,obj);
Customer*customer=p->getCustomer();
switch(JSVAL_TO_INT(id))
{
casename_prop:
{
std::stringname=customer->GetName();
JSString*str=JS_NewStringCopyN(cx,name.c_str(),name.length());
*vp=STRING_TO_JSVAL(str);
break;
}
caseage_prop:
*vp=INT_TO_JSVAL(customer->GetAge());
break;
}
}
returnJS_TRUE;
}
JSBoolJSCustomer::JSSetProperty(JSContext*cx,JSObject*obj,jsvalid,jsval*vp)
{
if(JSVAL_IS_INT(id))
{
JSCustomer*p=(JSCustomer*)JS_GetPrivate(cx,obj);
Customer*customer=p->getCustomer();
switch(JSVAL_TO_INT(id))
{
casename_prop:
{
JSString*str=JS_ValueToString(cx,*vp);
std::stringname=JS_GetStringBytes(str);
customer->SetName(name);
break;
}
caseage_prop:
customer->SetAge(JSVAL_TO_INT(*vp));
break;
}
}
returnJS_TRUE;
}
JSBoolJSCustomer::JSConstructor(JSContext*cx,JSObject*obj,uintNargc,
jsval*argv,jsval*rval)
{
JSCustomer*priv=newJSCustomer();
priv->setCustomer(newCustomer());
JS_SetPrivate(cx,obj,(void*)priv);
returnJS_TRUE;
}
voidJSCustomer::JSDestructor(JSContext*cx,JSObject*obj)
{
JSCustomer*priv=(JSCustomer*)JS_GetPrivate(cx,obj);
deletepriv;
priv=NULL;
}
JSObject*JSCustomer::JSInit(JSContext*cx,JSObject*obj,JSObject*proto)
{
JSObject*newProtoObj=JS_InitClass(cx,obj,proto,
&Customer_class,JSCustomer::JSConstructor,
0,NULL,JSCustomer::Customer_methods,NULL,NULL);
JS_DefineProperties(cx,newProtoObj,JSCustomer::Customer_properties);
returnnewProtoObj;
}
JSBoolJSCustomer::computeReduction(JSContext*cx,JSObject*obj,uintNargc,
jsval*argv,jsval*rval)
{
JSCustomer*p=(JSCustomer*)JS_GetPrivate(cx,obj);
if(p->getCustomer()->GetAge()<25)
*rval=INT_TO_JSVAL(10);
else
*rval=INT_TO_JSVAL(5);
returnJS_TRUE;
}

//Customer.h演示CustomerC++类的定义

#ifndef_Customer_H
#define_Customer_H

classCustomer
{
	public:
	intGetAge(){returnm_age;}
	voidSetAge(intnewAge){m_age=newAge;}
	std::stringGetName(){returnm_name;}
	voidSetName(std::stringnewName){m_name=newName;}
	private:
	intm_age;
	std::stringm_name;
};
#endif

//example.js演示JavaScript的例子

varc=newCustomer();
c.name="Franky";
c.age=32;
c.computeReduction();