v8::Context Class Reference

A sandboxed execution context with its own set of built-in objects and functions. More...

#include <v8.h>

Collaboration diagram for v8::Context:

Classes
class	Scope
	Stack-allocated class which sets the execution context for all operations executed within a local scope. More...

Public Member Functions
Local< Object >	Global ()
	Returns the global proxy object. More...
void	DetachGlobal ()
	Detaches the global object from its context before the global object can be reused to create a new context. More...
void	SetSecurityToken (Handle< Value > token)
	Sets the security token for the context. More...
void	UseDefaultSecurityToken ()
	Restores the security token to the default value. More...
Handle< Value >	GetSecurityToken ()
	Returns the security token of this context. More...
void	Enter ()
	Enter this context. More...
void	Exit ()
	Exit this context. More...
v8::Isolate *	GetIsolate ()
	Returns an isolate associated with a current context. More...
Local< Value >	GetEmbedderData (int index)
	Gets the embedder data with the given index, which must have been set by a previous call to SetEmbedderData with the same index. More...
void	SetEmbedderData (int index, Handle< Value > value)
	Sets the embedder data with the given index, growing the data as needed. More...
void *	GetAlignedPointerFromEmbedderData (int index)
	Gets a 2-byte-aligned native pointer from the embedder data with the given index, which must have bees set by a previous call to SetAlignedPointerInEmbedderData with the same index. More...
void	SetAlignedPointerInEmbedderData (int index, void *value)
	Sets a 2-byte-aligned native pointer in the embedder data with the given index, growing the data as needed. More...
void	AllowCodeGenerationFromStrings (bool allow)
	Control whether code generation from strings is allowed. More...
bool	IsCodeGenerationFromStringsAllowed ()
	Returns true if code generation from strings is allowed for the context. More...
void	SetErrorMessageForCodeGenerationFromStrings (Handle< String > message)
	Sets the error description for the exception that is thrown when code generation from strings is not allowed and 'eval' or the 'Function' constructor are called. More...

Static Public Member Functions
static Local< Context >	New (Isolate *isolate, ExtensionConfiguration *extensions=NULL, Handle< ObjectTemplate > global_template=Handle< ObjectTemplate >(), Handle< Value > global_object=Handle< Value >())
	Creates a new context and returns a handle to the newly allocated context. More...

Private Member Functions
Local< Value >	SlowGetEmbedderData (int index)
void *	SlowGetAlignedPointerFromEmbedderData (int index)

Friends
class	Value
class	Script
class	Object
class	Function

Detailed Description

A sandboxed execution context with its own set of built-in objects and functions.

Definition at line 5443 of file v8.h.

Member Function Documentation

AllowCodeGenerationFromStrings()

void v8::Context::AllowCodeGenerationFromStrings

(

bool

allow

)

Control whether code generation from strings is allowed.

Calling this method with false will disable 'eval' and the 'Function' constructor for code running in this context. If 'eval' or the 'Function' constructor are used an exception will be thrown.

If code generation from strings is not allowed the V8::AllowCodeGenerationFromStrings callback will be invoked if set before blocking the call to 'eval' or the 'Function' constructor. If that callback returns true, the call will be allowed, otherwise an exception will be thrown. If no callback is set an exception will be thrown.

Definition at line 5289 of file api.cc.

                                                       {
  i::Handle<i::Context> context = Utils::OpenHandle(this);
  i::Isolate* isolate = context->GetIsolate();
  ENTER_V8(isolate);
  context->set_allow_code_gen_from_strings(
      allow ? isolate->heap()->true_value() : isolate->heap()->false_value());
}

References ENTER_V8, v8::internal::Isolate::heap(), and v8::Utils::OpenHandle().

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DetachGlobal()

void v8::Context::DetachGlobal

(

)

Detaches the global object from its context before the global object can be reused to create a new context.

Definition at line 5281 of file api.cc.

                           {
  i::Handle<i::Context> context = Utils::OpenHandle(this);
  i::Isolate* isolate = context->GetIsolate();
  ENTER_V8(isolate);
  isolate->bootstrapper()->DetachGlobal(context);
}

References v8::internal::Isolate::bootstrapper(), ENTER_V8, and v8::Utils::OpenHandle().

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Enter()

void v8::Context::Enter

(

)

Enter this context.

After entering a context, all code compiled and run is compiled and run in this context. If another context is already entered, this old context is saved so it can be restored when the new context is exited.

Definition at line 612 of file api.cc.

                    {
  i::Handle<i::Context> env = Utils::OpenHandle(this);
  i::Isolate* isolate = env->GetIsolate();
  ENTER_V8(isolate);
  i::HandleScopeImplementer* impl = isolate->handle_scope_implementer();
  impl->EnterContext(env);
  impl->SaveContext(isolate->context());
  isolate->set_context(*env);
}

References v8::internal::Isolate::context(), ENTER_V8, v8::internal::HandleScopeImplementer::EnterContext(), v8::internal::Isolate::handle_scope_implementer(), v8::Utils::OpenHandle(), v8::internal::HandleScopeImplementer::SaveContext(), and v8::internal::Isolate::set_context().

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Exit()

void v8::Context::Exit

(

)

Exit this context.

Exiting the current context restores the context that was in place when entering the current context.

Definition at line 623 of file api.cc.

                   {
  i::Handle<i::Context> env = Utils::OpenHandle(this);
  i::Isolate* isolate = env->GetIsolate();
  ENTER_V8(isolate);
  i::HandleScopeImplementer* impl = isolate->handle_scope_implementer();
  if (!Utils::ApiCheck(impl->LastEnteredContextWas(env),
                       "v8::Context::Exit()",
                       "Cannot exit non-entered context")) {
    return;
  }
  impl->LeaveContext();
  isolate->set_context(impl->RestoreContext());
}

References v8::Utils::ApiCheck(), ENTER_V8, v8::internal::Isolate::handle_scope_implementer(), v8::internal::HandleScopeImplementer::LastEnteredContextWas(), v8::internal::HandleScopeImplementer::LeaveContext(), v8::Utils::OpenHandle(), v8::internal::HandleScopeImplementer::RestoreContext(), and v8::internal::Isolate::set_context().

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GetAlignedPointerFromEmbedderData()

void * v8::Context::GetAlignedPointerFromEmbedderData ( int  index )

inline

Gets a 2-byte-aligned native pointer from the embedder data with the given index, which must have bees set by a previous call to SetAlignedPointerInEmbedderData with the same index.

Note that index 0 currently has a special meaning for Chrome's debugger.

Definition at line 6954 of file v8.h.

                                                          {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Internals I;
  return I::ReadEmbedderData<void*>(this, index);
#else
  return SlowGetAlignedPointerFromEmbedderData(index);
#endif
}

References I.

Referenced by SetAlignedPointerInEmbedderData().

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GetEmbedderData()

Local< Value > v8::Context::GetEmbedderData ( int  index )

inline

Gets the embedder data with the given index, which must have been set by a previous call to SetEmbedderData with the same index.

Note that index 0 currently has a special meaning for Chrome's debugger.

Definition at line 6939 of file v8.h.

                                               {
#ifndef V8_ENABLE_CHECKS
  typedef internal::Object O;
  typedef internal::HeapObject HO;
  typedef internal::Internals I;
  HO* context = *reinterpret_cast<HO**>(this);
  O** result =
      HandleScope::CreateHandle(context, I::ReadEmbedderData<O*>(this, index));
  return Local<Value>(reinterpret_cast<Value*>(result));
#else
  return SlowGetEmbedderData(index);
#endif
}

References v8::HandleScope::CreateHandle(), and I.

Referenced by SetEmbedderData().

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GetIsolate()

v8::Isolate * v8::Context::GetIsolate

(

)

Returns an isolate associated with a current context.

Definition at line 5261 of file api.cc.

                               {
  i::Handle<i::Context> env = Utils::OpenHandle(this);
  return reinterpret_cast<Isolate*>(env->GetIsolate());
}

References v8::Utils::OpenHandle().

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GetSecurityToken()

Handle< Value > v8::Context::GetSecurityToken

(

)

Returns the security token of this context.

Definition at line 5252 of file api.cc.

                                          {
  i::Isolate* isolate = i::Isolate::Current();
  i::Handle<i::Context> env = Utils::OpenHandle(this);
  i::Object* security_token = env->security_token();
  i::Handle<i::Object> token_handle(security_token, isolate);
  return Utils::ToLocal(token_handle);
}

References v8::Utils::OpenHandle(), and v8::Utils::ToLocal().

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Global()

v8::Local< v8::Object > v8::Context::Global

(

)

Returns the global proxy object.

Global proxy object is a thin wrapper whose prototype points to actual context's global object with the properties like Object, etc. This is done that way for security reasons (for more details see https://wiki.mozilla.org/Gecko:SplitWindow).

Please note that changes to global proxy object prototype most probably would break VM—v8 expects only global object as a prototype of global proxy object.

Definition at line 5267 of file api.cc.

                                  {
  i::Handle<i::Context> context = Utils::OpenHandle(this);
  i::Isolate* isolate = context->GetIsolate();
  i::Handle<i::Object> global(context->global_proxy(), isolate);
  // TODO(dcarney): This should always return the global proxy
  // but can't presently as calls to GetProtoype will return the wrong result.
  if (i::Handle<i::JSGlobalProxy>::cast(
          global)->IsDetachedFrom(context->global_object())) {
    global = i::Handle<i::Object>(context->global_object(), isolate);
  }
  return Utils::ToLocal(i::Handle<i::JSObject>::cast(global));
}

References v8::Utils::OpenHandle(), and v8::Utils::ToLocal().

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IsCodeGenerationFromStringsAllowed()

bool v8::Context::IsCodeGenerationFromStringsAllowed

(

)

Returns true if code generation from strings is allowed for the context.

For more details see AllowCodeGenerationFromStrings(bool) documentation.

Definition at line 5298 of file api.cc.

                                                 {
  i::Handle<i::Context> context = Utils::OpenHandle(this);
  return !context->allow_code_gen_from_strings()->IsFalse();
}

References v8::Utils::OpenHandle().

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New()

Local< Context > v8::Context::New ( v8::Isolate *  external_isolate, v8::ExtensionConfiguration *  extensions = NULL, v8::Handle< ObjectTemplate >  global_template = Handle<ObjectTemplate>(), v8::Handle< Value >  global_object = Handle<Value>()  )

static

Creates a new context and returns a handle to the newly allocated context.

Parameters

isolate	The isolate in which to create the context.
extensions	An optional extension configuration containing the extensions to be installed in the newly created context.
global_template	An optional object template from which the global object for the newly created context will be created.
global_object	An optional global object to be reused for the newly created context. This global object must have been created by a previous call to Context::New with the same global template. The state of the global object will be completely reset and only object identify will remain.

Definition at line 5217 of file api.cc.

                                   {
  i::Isolate* isolate = reinterpret_cast<i::Isolate*>(external_isolate);
  LOG_API(isolate, "Context::New");
  ON_BAILOUT(isolate, "v8::Context::New()", return Local<Context>());
  i::HandleScope scope(isolate);
  ExtensionConfiguration no_extensions;
  if (extensions == NULL) extensions = &no_extensions;
  i::Handle<i::Context> env =
      CreateEnvironment(isolate, extensions, global_template, global_object);
  if (env.is_null()) return Local<Context>();
  return Utils::ToLocal(scope.CloseAndEscape(env));
}

References v8::internal::HandleScope::CloseAndEscape(), v8::CreateEnvironment(), v8::internal::Handle< T >::is_null(), LOG_API, NULL, ON_BAILOUT, and v8::Utils::ToLocal().

Referenced by v8::Shell::CreateEvaluationContext(), v8::Shell::InitializeDebugger(), main(), and v8::Shell::RealmCreate().

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SetAlignedPointerInEmbedderData()

void v8::Context::SetAlignedPointerInEmbedderData	(	int	index,
		void *	value
	)

Sets a 2-byte-aligned native pointer in the embedder data with the given index, growing the data as needed.

Note that index 0 currently has a special meaning for Chrome's debugger.

Definition at line 702 of file api.cc.

                                                                    {
  const char* location = "v8::Context::SetAlignedPointerInEmbedderData()";
  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, true, location);
  data->set(index, EncodeAlignedAsSmi(value, location));
  DCHECK_EQ(value, GetAlignedPointerFromEmbedderData(index));
}

References DCHECK_EQ, v8::EmbedderDataFor(), v8::EncodeAlignedAsSmi(), and GetAlignedPointerFromEmbedderData().

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SetEmbedderData()

void v8::Context::SetEmbedderData	(	int	index,
		v8::Handle< Value >	value
	)

Sets the embedder data with the given index, growing the data as needed.

Note that index 0 currently has a special meaning for Chrome's debugger.

Definition at line 683 of file api.cc.

                                                              {
  const char* location = "v8::Context::SetEmbedderData()";
  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, true, location);
  if (data.is_null()) return;
  i::Handle<i::Object> val = Utils::OpenHandle(*value);
  data->set(index, *val);
  DCHECK_EQ(*Utils::OpenHandle(*value),
            *Utils::OpenHandle(*GetEmbedderData(index)));
}

References DCHECK_EQ, v8::EmbedderDataFor(), GetEmbedderData(), v8::internal::Handle< T >::is_null(), and v8::Utils::OpenHandle().

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SetErrorMessageForCodeGenerationFromStrings()

void v8::Context::SetErrorMessageForCodeGenerationFromStrings

(

Handle< String >

message

)

Sets the error description for the exception that is thrown when code generation from strings is not allowed and 'eval' or the 'Function' constructor are called.

Definition at line 5304 of file api.cc.

                          {
  i::Handle<i::Context> context = Utils::OpenHandle(this);
  i::Handle<i::String> error_handle = Utils::OpenHandle(*error);
  context->set_error_message_for_code_gen_from_strings(*error_handle);
}

References v8::Utils::OpenHandle().

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SetSecurityToken()

void v8::Context::SetSecurityToken

(

Handle< Value >

token

)

Sets the security token for the context.

To access an object in another context, the security tokens must match.

Definition at line 5235 of file api.cc.

                                                    {
  i::Isolate* isolate = i::Isolate::Current();
  ENTER_V8(isolate);
  i::Handle<i::Context> env = Utils::OpenHandle(this);
  i::Handle<i::Object> token_handle = Utils::OpenHandle(*token);
  env->set_security_token(*token_handle);
}

References ENTER_V8, and v8::Utils::OpenHandle().

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SlowGetAlignedPointerFromEmbedderData()

void * v8::Context::SlowGetAlignedPointerFromEmbedderData ( int  index )

private

Definition at line 694 of file api.cc.

                                                              {
  const char* location = "v8::Context::GetAlignedPointerFromEmbedderData()";
  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, false, location);
  if (data.is_null()) return NULL;
  return DecodeSmiToAligned(data->get(index), location);
}

References v8::DecodeSmiToAligned(), v8::EmbedderDataFor(), v8::internal::Handle< T >::is_null(), and NULL.

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SlowGetEmbedderData()

v8::Local< v8::Value > v8::Context::SlowGetEmbedderData ( int  index )

private

Definition at line 674 of file api.cc.

                                                       {
  const char* location = "v8::Context::GetEmbedderData()";
  i::Handle<i::FixedArray> data = EmbedderDataFor(this, index, false, location);
  if (data.is_null()) return Local<Value>();
  i::Handle<i::Object> result(data->get(index), data->GetIsolate());
  return Utils::ToLocal(result);
}

References v8::EmbedderDataFor(), v8::internal::Handle< T >::is_null(), and v8::Utils::ToLocal().

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UseDefaultSecurityToken()

void v8::Context::UseDefaultSecurityToken

(

)

Restores the security token to the default value.

Definition at line 5244 of file api.cc.

                                        {
  i::Isolate* isolate = i::Isolate::Current();
  ENTER_V8(isolate);
  i::Handle<i::Context> env = Utils::OpenHandle(this);
  env->set_security_token(env->global_object());
}

References ENTER_V8, and v8::Utils::OpenHandle().

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Friends And Related Function Documentation

Function

friend class Function

friend

Definition at line 5594 of file v8.h.

Object

friend class Object

friend

Definition at line 5593 of file v8.h.

Script

friend class Script

friend

Definition at line 5592 of file v8.h.

Value

friend class Value

friend

Definition at line 5591 of file v8.h.

---

The documentation for this class was generated from the following files:

• /mnt/V8SourceCode/include/v8.h
• /mnt/V8SourceCode/src/api.cc