在C++中嵌入JavaScript——Google V8 JavaScript Engine使用体验

Google V8 Script Engine 使用体验

Google V8 JavaScript Engine是google为 Chrome's浏览器开发的脚本引擎,现在可以使用V8 JavaScript Engine在C++程序中建立自己的脚本环境。

 

1.准备工作

1). 安装一个SVN客户端 http://tortoisesvn.net/downloads,google v8 在官方网站仅以此方式发布;

2).下载一个python:地址http://sourceforge.net/projects/pywin32/files/,官方网站2009年10月15日被墙了

 

2.checkout并准备环境

      0)设置目录:

+third_party

+python_24         Python位置(拷贝或安装到均可)

       +V8 V8 check out 位置

1)安装python

---------------------------------------begin-------------------------------------------------

     说明:

由于v8.project在配置时,使用如下命令进行处理:

.\d8js2c.cmd ..\..\src "$(IntDir)\DerivedSources"

其中: d8js2c.cmd(line4): set PYTHON="..\..\..\third_party\python_24\python.exe"

显然python和相关库应该位于:..\..\..\third_party\python_24\

---------------------------------------end---------------------------------------------------

2)下载 Google V8 Script Engine下载,

      SVN地址: http://code.google.com/p/v8/source/checkout

 

3)编译

V8\tools\visual_studio\v8.sln

这样就可以编译了,如果编译失败,那可能就是python没有配置好。

 

3. JS 嵌入C++示例代码

一个Hello world!

#include "http://www.cnblogs.com/include/v8.h"
#pragma comment(lib,"../visual_studio/Release/lib/v8.lib")
#pragma comment(lib,"../visual_studio/Release/lib/v8_base.lib")

using namespace v8;

int main(int argc, char* argv[]) {

// Create a stack-allocated handle scope.
HandleScope handle_scope;

// Create a new context.
Persistent<Context> context = Context::New();

// Enter the created context for compiling and
// running the hello world script.
Context::Scope context_scope(context);

// Create a string containing the JavaScript source code.
Handle<String> source = String::New("'Hello' + ', World!'");

// Compile the source code.
Handle<Script> script = Script::Compile(source);

// Run the script to get the result.
Handle<Value> result = script->Run();

// Dispose the persistent context.
context.Dispose();

// Convert the result to an ASCII string and print it.
String::AsciiValue ascii(result);
printf(
"%s\n", *ascii);
return 0;
}

 

更多示例代码参考:V8\test\cctest\*.cc

4.支持C++类

CProxyV8提供便利的方式将C++类的属性和方法导出到JavaScript环境中。支持generic Functors,不需要为每个属性和方法设置回调函数。

 

 

 

class Point
{
public:
/** Constructor without params is required */
Point(
int px = 0, int py = 0) : x_(px), y_(py) {}
Point(Point
* p) : x_(p->x_), y_(p->y_) {}

int x_;
int y_;

/** Example call to function without params */
int GetManhattanLength() { return std::abs(x_) - std::abs(y_); }

/** this will create a JS object, with JS destructor */
Point
* Copy() { return new Point(); }

/** Example call to function with params */
v8::Handle
<v8::Value> Translate(const v8::Arguments& args)
{
// throw if we didn't get 2 args
if (args.Length() != 2)
return ThrowException(v8::String::New("Expected 2 arguments"));

x_
+= args[0]->Int32Value();
y_
+= args[1]->Int32Value();
return v8::True();
};
};

class Line
{
public:
/** Constructor without params is required */

/** Example of object property, it can be manipulate directly */
Point start;

/** this will create a JS object, without destructor and a reference to this
* end instance
*
*/
Point
& GetEnd() { return end; }

private:
Point end;
};

int main(int argc, char* argv[])
{
v8::V8::SetFlagsFromCommandLine(
&argc, argv, true);
v8::HandleScope handle_scope;

// Create a template for the global object.
v8::Handle<v8::ObjectTemplate> global = v8::ObjectTemplate::New();

ProxyClass
<Foo>* pPoint = ProxyClass<Foo>::instance(); //Get the proxy class for Point

pPoint
->Expose(&Point::x_,"x",true,true); //expose x_ for read/write
pPoint->Expose(&Point::y_,"y",true,true); //expose y_ for read/write

pPoint
->Expose(&Point::Copy, "copy");
pPoint
->Expose(&Point::GetManhattanLength, "getManhattanLength");
pPoint
->Expose(&Point::Translate, "translate");

ProxyClass
<Line>* pLine = ProxyClass<Line>::instance(); //Get the proxy class for Line
pPoint->Expose(&Line::start,"start",true,true); //expose object start for read/write
pPoint->Expose(&Line::GetEnd, "getEnd");

global->Set(v8::String::New("Point"), pPoint->GetFunctionTemplate()); // add Point to JS
global->Set(v8::String::New("Line"), pLine->GetFunctionTemplate()); // add Line to JS
...

 

如果借助宏,就较简单:

int main(int argc, char* argv[])
{
v8::V8::SetFlagsFromCommandLine(
&argc, argv, true);
v8::HandleScope handle_scope;

// Create a template for the global object.
v8::Handle<v8::ObjectTemplate> global = v8::ObjectTemplate::New();

CPROXYV8_PROPERTY_ID(Point,x_,x,
true,true);
CPROXYV8_PROPERTY_ID(Point,y_,y,
true,true);

CPROXYV8_METHOD_ID(Point,Copy, copy);
CPROXYV8_METHOD_ID(Point,GetManhattanLength, getManhattanLength);
CPROXYV8_METHOD(Point,Translate);

CPROXYV8_PROPERTY(Line,start,
true,true);

CPROXYV8_METHOD_ID(Line,GetEnd,getEnd);

global->Set(v8::String::New("Point"), CPROXYV8_CLASS(Point)->GetFunctionTemplate()); // add Point to JS
global->Set(v8::String::New("Line"), CPROXYV8_CLASS(Line)->GetFunctionTemplate()); // add Line to JS

 

 

在Shell中使用这些类:

V8 version 0.4.3.1
> x = new Point()
[object Point]
> line = new Line()
[object Line]
> x.x
0
> x.x = 10
10
> line.getEnd().x
0
> line.getEnd().x = 10
10
> line.getEnd().x
10
> end = line.getEnd();
[object Point]
> end.x
10
> end.Translate(10,10)
true
> end.x
20
> line.getEnd().x
20
> x.x
10
>_

 

  

官方网站:

http://code.google.com/p/v8/

http://code.google.com/p/cproxyv8/

posted @ 2010-02-21 00:54  JohnsonFeng  阅读(16211)  评论(10编辑  收藏  举报