[转]基于 C 语言的 JavaScript 引擎探索

alter("something");

window.alter("something");

# 解压缩
 tar xvzf js-1.7.0.tar.gz 

 # 切换至源码目录
 cd js-1.7.0/src 

 # 编译
 make -f Makefile.ref

# 创建非 debug 模式的库
 make BUILD_OPT=1 -f Makefile.ref

object

OBJECT_TO_JSVAL(o)

JSVAL_TO_OBJECT(v)

#include "jsapi.h"

/* 全局变量的类声明 */ 
static JSClass global_class = { 
    "global", 
    JSCLASS_GLOBAL_FLAGS, 
    JS_PropertyStub, 
    JS_PropertyStub, 
    JS_PropertyStub, 
    JS_PropertyStub, 
    JS_EnumerateStub, 
    JS_ResolveStub, 
    JS_ConvertStub, 
    JS_FinalizeStub, 
    JSCLASS_NO_OPTIONAL_MEMBERS 
 };

/* 错误处理函数，用于回调，打印详细信息 */ 
 void report_error(JSContext *cx,  const char *message, JSErrorReport *report){ 
    fprintf(stderr, "%s:%u:%s/n", 
    		 report->filename ? report->filename : "<no filename>", 
            (unsigned int) report->lineno, 
            message); 
 }

int main(int argc, char *argv[]){ 
    JSRuntime *runtime; 
    JSContext *context; 
    JSObject *global; 

	 // 创建新的运行时 8M 
    runtime = JS_NewRuntime(8L * 1024L * 1024L); 
    if (runtime == NULL){ 
        return -1; 
    } 

	 // 创建新的上下文
    context = JS_NewContext(runtime, 8*1024); 
    if (context == NULL){ 
        return -1; 
    } 

	 // 
    JS_SetOptions(context, JSOPTION_VAROBJFIX); 
    // 设置错误回调函数 , report_error 函数定义如上
	 JS_SetErrorReporter(context, report_error); 

	 // 创建一个新的 JavaScript 对象
    global = JS_NewObject(context, &global_class, NULL, NULL); 
    if (global == NULL){ 
        return -1; 
    } 

	 // 实例化 global, 加入对象，数组等支持
    if (!JS_InitStandardClasses(context, global)){ 
        return -1; 
    } 

	 // 
	 // 使用 global, context 等来完成其他操作，用户定制代码由此开始
	 // 

	 // 释放上下文对象
    JS_DestroyContext(context); 
	 // 释放运行时环境
    JS_DestroyRuntime(runtime); 
	 // 停止 JS 虚拟机
    JS_ShutDown(); 

	 return 0; 
 }

JSBool JS_EvaluateScript(JSContext *cx, JSObject *obj, 
    const char *src, uintN length, const
				char *filename, 
    uintN lineno, jsval *rval);

char *script = "(function(a, b){return a * b;})(15, 6);"; 
	 jsval rval; 

	 status = JS_EvaluateScript(context, global, script, strlen(script)/ 
	        , NULL, 0, &rval); 

	 if (status == JS_TRUE){ 
	    jsdouble d; 
	    JS_ValueToNumber(context, rval, &d); 
	    printf("eval result = %f/n", d); 
	 }

eval result = 90.000000

JSBool evalScriptFromFile(JSContext *cntext, const
	char *file){ 
    JSScript *script; 
    JSString *jss; 
    JSBool status; 
    jsval value; 

    //get the global object 
    JSObject *global = JS_GetGlobalObject(context); 

    //compile the script for further using 
    script = JS_CompileFile(context, global, file); 

    if (script == NULL){ 
        return JS_FALSE; 
    } 

    //execute it once 
    status = JS_ExecuteScript(context, global, script, &value); 
    jss = JS_ValueToString(context, value); 
    printf("eval script result is : %s/n", JS_GetStringBytes(jss)); 

    //destory the script object 
    JS_DestroyScript(context, script); 

    return status; 
 }

JSBool status = evalScriptFromFile(context, "jstest.js"); 
 if (status == JS_FALSE){ 
        fprintf(stderr, "error while evaluate the script/n"); 
 }

varPerson = function(name){ 
    var _name_ = name; 
    this.getName = function(){ 
        return _name_; 
    } 

    this.setName = function(newname){ 
        _name_ = newname; 
    } 
 } 

 varjack = new Person("jack"); 
 jack.setName("john"); 
 // 最后一句将作为脚本的执行结果返回给 C 代码
 jack.getName();

eval script result is : john

function add(x, y){ 
    return x + y; 
 }

JSBool func_test(JSContext *context){ 
    jsval res; 
    JSObject *global = JS_GetGlobalObject(context); 
    jsval argv[2]; 

    //new 2 number to pass into the function "add" in script 
    JS_NewNumberValue(context, 18.5, &res); 
    argv[0] = res; 
    JS_NewNumberValue(context, 23.1, &res); 
    argv[1] = res; 

    JS_CallFunctionName(context, global, "add", 2, argv, &res); 

    jsdouble d; 

    //convert the result to jsdouble 
    JS_ValueToNumber(context, res, &d); 
    printf("add result = %f/n", d); 

    return JS_TRUE; 
 }

JSBool  JS_CallFunctionName(JSContext *cx, JSObject *obj, 
 const char *name, uintN argc, jsval *argv, jsval *rval);

cx

JSContext *

obj

JSObject *

name

const char *

argc

uintN

argv

jsval *

rval

jsval *

//log user log in information 
 logging("user jack login on 2010/7/6"); 

 //user do nothing else 
 nothing(); 

 //log user log out information 
 logging("user jack logout on 2010/7/7"); 

 function print(){ 
    for (vari = 0; i < arguments.length; i++){ 
        logging(arguments[i]); 
    } 
 } 

 print("hello", "all", "my", "friend");

/** 
 * define an exposed function to be used in scripts 
 * print out all the incoming arguments as string. 
 */ 
 static JSBool  logging(JSContext *context, JSObject *object, uintN argc, 
        jsval *argv, jsval *value){ 
    int i = 0; 
    JSString *jss; 

    for(i = 0; i < argc; i++){ 
       jss = JS_ValueToString(context, argv[i]); 
       printf("message from script environment : %s/n", / 
               JS_GetStringBytes(jss)); 
    } 
    return JS_TRUE; 
 } 

 /** 
 * define an exposed function to be used in scripts 
 * do nothing but print out a single line. 
 */ 
 static JSBool  nothing(JSContext *context, 
 JSObject *object, uintN argc, jsval *argv, jsval *value) 
 { 
    printf("got nothing to do at all/n"); 
    return JS_TRUE; 
 }

static JSFunctionSpec functions[] = { 
    {"logging", logging, LOG_MINARGS, 0, 0}, 
    {"nothing", nothing, NOT_MINARGS, 0, 0}, 
    {0, 0, 0, 0, 0} 
 }; 

    //define function list here 
    if (!JS_DefineFunctions(context, global, functions)){ 
        return -1; 
 }

message from script environment : user jack login on 2010/7/6 
 got nothing to do at all 
 message from script environment : user jack logout on 2010/7/7 
 message from script environment : hello 
 message from script environment : all 
 message from script environment : my 
 message from script environment : friend

typedef struct{ 
    char name[32]; 
    char addr[128]; 
 }PersonInfo;

enum person{ 
    NAME, 
    ADDRESS
 };

//define person properties 
 JSPropertySpec pprops[] = { 
    {"name", NAME, JSPROP_ENUMERATE}, 
    {"address", ADDRESS, JSPROP_ENUMERATE}, 
    {0} 
 };

//define person methods 
 JSFunctionSpec pfuncs[] = { 
    {"print", printing, 0}, 
    {"getName", getName, 0}, 
    {"setName", setName, 0}, 
    {"getAddress", getAddress, 0}, 
    {"setAddress", setAddress, 0}, 
    {0} 
 };

//define person class (JSClass) 
 JSClass pclass = { 
    "person", 0, 
    JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, JS_PropertyStub, 
    JS_EnumerateStub, JS_ResolveStub, JS_ConvertStub, JS_FinalizeStub 
 };

JSObject *person; 

    //define the object 
    person = JS_DefineObject(/ 
            context, global, "person", &pclass, 0, JSPROP_ENUMERATE); 

    //install the properties and methods on the person object 
    JS_DefineProperties(context, person, pprops); 
    JS_DefineFunctions(context, person, pfuncs);

//undefined of course 
 person.print(); 

 //person.name = "abruzzi"; 
 //person.address = "Huang Quan Road"; 

 person.setName("Desmond"); 
 person.setAddress("HuangQuan Road"); 

 //print is global function, access properties directly 
 print("person name = " + person.name); 
 print("person address = " + person.address); 

 person.print(); 

 (function(){ 
    //using getter/setter to access properties 
    return person.getName() + " : " + person.getAddress(); 
 })();

name : undefined
 address : undefined
 person name = Desmond 
 person address = HuangQuan Road 
 name : Desmond 
 address : HuangQuan Road 
 eval script result is : Desmond : HuangQuan Road