Javascript 使用v8 shell中的stringify
我正在创建一个基于v8 shell的控制台,我使用了v8附带的示例代码,它运行得很好,但我试图将v8::object转换为它的字符串版本(json),但没有找到一种方法 下面是我在shell.cc中的示例代码:Javascript 使用v8 shell中的stringify,javascript,v8,stringify,Javascript,V8,Stringify,我正在创建一个基于v8 shell的控制台,我使用了v8附带的示例代码,它运行得很好,但我试图将v8::object转换为它的字符串版本(json),但没有找到一种方法 下面是我在shell.cc中的示例代码: v8::Handle test(const v8::Arguments& args) { v8::HandleScope handle_scope; const char* json; v8::String::Utf8Value
v8::Handle test(const v8::Arguments& args) {
v8::HandleScope handle_scope;
const char* json;
v8::String::Utf8Value strJson(args[0]);
printf(ToCString(json));
if (args[0]->IsObject()) {
printf("it's an object\n");
}
return v8::String::New("");
}
在shell中,我创建了一个文件test.js,其中包含以下内容:
var a = { name: 'John' };
test(a);
在shell控制台中执行js后,我得到了这个结果:
[object Object]
It's an object
我想要的是:
{ "name": "John" }
如果我将js代码更改为:
var a = { name: 'John'}
test(JSON.stringify(a));
它工作得很好,但我不想让用户知道如何将javascript变量解析为json,我也不想检查对象上的每个输入并手动解析它
有没有办法在C中的shell.cc代码中执行相同的指令?比如:
v8::Handle<v8::String> temp = JSON.parse(arg[0]);
v8::Handle temp=JSON.parse(arg[0]);
更新:这就是我处理这件事的方式,但我想要一个更干净的方法来做同样的事情:
const char* toJson(const v8::Local<v8::Object>& obj) {
std::stringstream ss;
ss << "{";
v8::Local<v8::Array> propertyNames = obj->GetPropertyNames();
for (int x = 0; x < propertyNames->Length(); x++) {
if (x != 0) {
ss << ", ";
}
v8::String::Utf8Value name(propertyNames->Get(x));
ss << "\"" << ToCString(name) << "\":";
v8::Local<v8::Value> val = obj->GetInternalField(x);
if (val->IsObject()) {
ss << toJson(val->ToObject());
} else {
ss << "\"" << ToCString(v8::String::Utf8Value(val)) << "\"";
}
}
ss << "}";
const char* result = ss.str().c_str();
return result;
}
v8::Handle test(const v8::Arguments& args) {
v8::HandleScope handle_scope;
const char* json;
v8::String::Utf8Value strJson(args[0]);
if (args[0]->IsObject()) {
char* json = toJson(args[0]);
// ...
// Some operations with the json
// ...
}
return v8::String::New("");
}
const char*toJson(const v8::Local和obj){
std::stringstream-ss;
ss GetPropertyNames();
对于(int x=0;xLength();x++){
如果(x!=0){
ss-Get(x));
ss-GetInternalField(x);
如果(val->IsObject()){
ss-ToObject());
}否则{
ss我发现这种方法可以使用v8s内置的JSON.parse
函数实现反向操作(JSON到v8对象)
将其调整为使用JSON.stringify
会有点像这样(未经测试):
handletojson(句柄对象)
{
手镜镜;
句柄上下文=上下文::GetCurrent();
句柄全局=上下文->全局();
Handle JSON=global->Get(String::New(“JSON”)->ToObject();
handlejson_stringify=Handle::Cast(JSON->Get(String::New(“stringify”));
返回scope.Close(JSON_stringify->Call(JSON,1,object));
}
我想避免在自己实现的V8::Value
-to-string
转换中使用现在不推荐的V8方法,所以我从Michael的答案中汲取灵感,将此函数组合在一起。缺点是它非常冗长:
bool MakeStringValue(const string& str, v8::Isolate* isolate,
v8::Handle<v8::Value>* out_value) {
const v8::MaybeLocal<v8::String> maybe_string = v8::String::NewFromUtf8(
isolate, str.c_str(), v8::NewStringType::kNormal, str.size());
v8::Handle<v8::String> value;
if (!maybe_string.ToLocal(&value)) {
return false;
}
*out_value = static_cast<v8::Handle<v8::Value>>(value);
return true;
}
bool ConvertValueToString(v8::Handle<v8::Value> value, v8::Isolate* isolate,
v8::Local<v8::Context> context,
string* value_string) {
v8::Local<v8::Object> global = context->Global();
v8::Handle<v8::Value> json_string_value;
v8::Handle<v8::Value> stringify_string_value;
if (!MakeStringValue("JSON", isolate, &json_string_value) ||
!MakeStringValue("stringify", isolate, &stringify_string_value)) {
return false;
}
const v8::MaybeLocal<v8::Value> maybe_json_value =
global->Get(context, json_string_value);
v8::Handle<v8::Value> json_value;
if (!maybe_json_value.ToLocal(&json_value)) {
return false;
}
v8::MaybeLocal<v8::Object> maybe_json_object = json_value->ToObject(context);
v8::Handle<v8::Object> json_object;
if (!maybe_json_object.ToLocal(&json_object)) {
return false;
}
const v8::MaybeLocal<v8::Value> maybe_stringify_value =
json_object->Get(context, stringify_string_value);
v8::Handle<v8::Value> stringify_value;
if (!maybe_stringify_value.ToLocal(&stringify_value)) {
return false;
}
v8::Function* stringify_function = v8::Function::Cast(*stringify_value);
v8::TryCatch try_catch(isolate);
const v8::MaybeLocal<v8::Value> maybe_result =
stringify_function->Call(context, json_object, 1, &value);
v8::Local<v8::Value> result;
if (try_catch.HasCaught() || !maybe_result.ToLocal(&result) ||
result.IsEmpty() || result->IsNullOrUndefined() || !result->IsString()) {
return false;
}
v8::Local<v8::String> result_string;
if (!result->ToString(context).ToLocal(&result_string)) {
return false;
}
v8::String::Utf8Value utf8_value(result_string);
// operator* returns a const char*.
if (*utf8_value == nullptr) {
return false;
}
value_string->assign(*utf8_value, utf8_value.length());
return true;
}
bool MakeStringValue(const string&str,v8::Isolate*Isolate,
v8::句柄*输出值){
常量v8::Maybellocal可能\u string=v8::string::NewFromUtf8(
孤立,str.c_str(),v8::NewStringType::kNormal,str.size();
v8::句柄值;
if(!maybe_string.ToLocal(&value)){
返回false;
}
*输出值=静态值;
返回true;
}
bool ConvertValueToString(v8::句柄值,v8::隔离*隔离,
v8::本地上下文,
字符串*值(字符串){
v8::Local global=context->global();
v8::处理json_字符串_值;
v8::Handle stringify_string_value;
如果(!MakeStringValue(“JSON”,隔离,&JSON\u字符串\u值)||
!MakeStringValue(“字符串化、隔离和字符串化\u字符串\u值)){
返回false;
}
const v8::MaybeLocal maybe_json_值=
全局->获取(上下文,json字符串值);
v8::处理json_值;
if(!maybe_json_value.ToLocal(&json_value)){
返回false;
}
v8::MaybeLocal maybe_json_object=json_value->ToObject(上下文);
处理json_对象;
if(!maybe_json_object.ToLocal(&json_object)){
返回false;
}
常量v8::MaybeLocal可能会字符串化值=
json_object->Get(上下文、字符串化_字符串_值);
v8::句柄字符串化_值;
if(!maybe_stringify_value.ToLocal(&stringify_value)){
返回false;
}
v8::Function*stringify_Function=v8::Function::Cast(*stringify_值);
v8::TryCatch try_catch(隔离);
常量v8::Maybellocal可能是结果=
stringify_函数->调用(上下文、json_对象、1和值);
v8:局部结果;
如果(try_catch.hascapt()||!可能_result.ToLocal(&result)||
result.IsEmpty()| | result->IsNullOrUndefined()| |!result->IsString()){
返回false;
}
v8::本地结果_字符串;
if(!result->ToString(上下文).ToLocal(&result\u字符串)){
返回false;
}
v8::String::Utf8Value utf8\u值(结果\u字符串);
//运算符*返回常量字符*。
如果(*utf8_值==nullptr){
返回false;
}
value\u string->assign(*utf8\u value,utf8\u value.length());
返回true;
}
如果您使用的是较新的V8(如8.3),代码如下:
void静态jsonStringify(v8::本地上下文,v8::本地值){
自动隔离=上下文->获取隔离();
自动全局=上下文->全局();
auto json=global->Get(context,v8::String::NewFromUtf8(隔离,“json”,v8::NewStringType::kNormal).ToLocalChecked()).ToLocalChecked().As();
auto stringify=json->Get(上下文,v8::String::NewFromUtf8(隔离,“stringify”,v8::NewStringType::kNormal).ToLocalChecked()).ToLocalChecked().As();
auto v=stringify->Call(上下文、未定义(隔离)、1和值);
v8::String::Utf8Value json_值(隔离,v);
标准::cout
bool MakeStringValue(const string& str, v8::Isolate* isolate,
v8::Handle<v8::Value>* out_value) {
const v8::MaybeLocal<v8::String> maybe_string = v8::String::NewFromUtf8(
isolate, str.c_str(), v8::NewStringType::kNormal, str.size());
v8::Handle<v8::String> value;
if (!maybe_string.ToLocal(&value)) {
return false;
}
*out_value = static_cast<v8::Handle<v8::Value>>(value);
return true;
}
bool ConvertValueToString(v8::Handle<v8::Value> value, v8::Isolate* isolate,
v8::Local<v8::Context> context,
string* value_string) {
v8::Local<v8::Object> global = context->Global();
v8::Handle<v8::Value> json_string_value;
v8::Handle<v8::Value> stringify_string_value;
if (!MakeStringValue("JSON", isolate, &json_string_value) ||
!MakeStringValue("stringify", isolate, &stringify_string_value)) {
return false;
}
const v8::MaybeLocal<v8::Value> maybe_json_value =
global->Get(context, json_string_value);
v8::Handle<v8::Value> json_value;
if (!maybe_json_value.ToLocal(&json_value)) {
return false;
}
v8::MaybeLocal<v8::Object> maybe_json_object = json_value->ToObject(context);
v8::Handle<v8::Object> json_object;
if (!maybe_json_object.ToLocal(&json_object)) {
return false;
}
const v8::MaybeLocal<v8::Value> maybe_stringify_value =
json_object->Get(context, stringify_string_value);
v8::Handle<v8::Value> stringify_value;
if (!maybe_stringify_value.ToLocal(&stringify_value)) {
return false;
}
v8::Function* stringify_function = v8::Function::Cast(*stringify_value);
v8::TryCatch try_catch(isolate);
const v8::MaybeLocal<v8::Value> maybe_result =
stringify_function->Call(context, json_object, 1, &value);
v8::Local<v8::Value> result;
if (try_catch.HasCaught() || !maybe_result.ToLocal(&result) ||
result.IsEmpty() || result->IsNullOrUndefined() || !result->IsString()) {
return false;
}
v8::Local<v8::String> result_string;
if (!result->ToString(context).ToLocal(&result_string)) {
return false;
}
v8::String::Utf8Value utf8_value(result_string);
// operator* returns a const char*.
if (*utf8_value == nullptr) {
return false;
}
value_string->assign(*utf8_value, utf8_value.length());
return true;
}