v8  6.8.275 (node 10.15.3)
V8 is Google's open source JavaScript engine
Context Class Reference

#include <v8.h>

Data Structures

class  BackupIncumbentScope
class  Scope

Public Types

enum  EmbedderDataFields { kDebugIdIndex = 0 }

Public Member Functions

Local< ObjectGlobal ()
void DetachGlobal ()
void SetSecurityToken (Local< Value > token)
void UseDefaultSecurityToken ()
Local< ValueGetSecurityToken ()
void Enter ()
void Exit ()
IsolateGetIsolate ()
uint32_t GetNumberOfEmbedderDataFields ()
V8_INLINE Local< ValueGetEmbedderData (int index)
Local< ObjectGetExtrasBindingObject ()
void SetEmbedderData (int index, Local< Value > value)
V8_INLINE void * GetAlignedPointerFromEmbedderData (int index)
void SetAlignedPointerInEmbedderData (int index, void *value)
void AllowCodeGenerationFromStrings (bool allow)
bool IsCodeGenerationFromStringsAllowed ()
void SetErrorMessageForCodeGenerationFromStrings (Local< String > message)
template<class T >
V8_INLINE MaybeLocal< T > GetDataFromSnapshotOnce (size_t index)
template<class T >
MaybeLocal< T > GetDataFromSnapshotOnce (size_t index)

Static Public Member Functions

static Local< ContextNew (Isolate *isolate, ExtensionConfiguration *extensions=NULL, MaybeLocal< ObjectTemplate > global_template=MaybeLocal< ObjectTemplate >(), MaybeLocal< Value > global_object=MaybeLocal< Value >(), DeserializeInternalFieldsCallback internal_fields_deserializer=DeserializeInternalFieldsCallback())
static MaybeLocal< ContextFromSnapshot (Isolate *isolate, size_t context_snapshot_index, DeserializeInternalFieldsCallback embedder_fields_deserializer=DeserializeInternalFieldsCallback(), ExtensionConfiguration *extensions=nullptr, MaybeLocal< Value > global_object=MaybeLocal< Value >())
static MaybeLocal< ObjectNewRemoteContext (Isolate *isolate, Local< ObjectTemplate > global_template, MaybeLocal< Value > global_object=MaybeLocal< Value >())


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 8754 of file v8.h.

Member Enumeration Documentation

◆ EmbedderDataFields

The field at kDebugIdIndex used to be reserved for the inspector. It now serves no purpose.


Definition at line 8881 of file v8.h.

Member Function Documentation

◆ AllowCodeGenerationFromStrings()

void 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.

◆ DetachGlobal()

void DetachGlobal ( )

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

◆ Enter()

void 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.

Referenced by Context::Scope::Scope().

◆ Exit()

void Exit ( )

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

Referenced by Context::Scope::~Scope().

◆ FromSnapshot()

static MaybeLocal<Context> FromSnapshot ( Isolate isolate,
size_t  context_snapshot_index,
DeserializeInternalFieldsCallback  embedder_fields_deserializer = DeserializeInternalFieldsCallback(),
ExtensionConfiguration extensions = nullptr,
MaybeLocal< Value global_object = MaybeLocalValue >() 

Create a new context from a (non-default) context snapshot. There is no way to provide a global object template since we do not create a new global object from template, but we can reuse a global object.

isolateSee v8::Context::New.
context_snapshot_indexThe index of the context snapshot to deserialize from. Use v8::Context::New for the default snapshot.
embedder_fields_deserializerOptional callback to deserialize internal fields. It should match the SerializeInternalFieldCallback used to serialize.
extensionsSee v8::Context::New.
global_objectSee v8::Context::New.

◆ GetAlignedPointerFromEmbedderData()

void * GetAlignedPointerFromEmbedderData ( int  index)

Gets a 2-byte-aligned native pointer from the embedder data with the given index, which must have been 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 10488 of file v8.h.

References Internals::ReadEmbedderData().

◆ GetDataFromSnapshotOnce() [1/2]

V8_INLINE MaybeLocal<T> GetDataFromSnapshotOnce ( size_t  index)

Return data that was previously attached to the context snapshot via SnapshotCreator, and removes the reference to it. Repeated call with the same index returns an empty MaybeLocal.

◆ GetDataFromSnapshotOnce() [2/2]

MaybeLocal<T> GetDataFromSnapshotOnce ( size_t  index)

Definition at line 10498 of file v8.h.

References Local< T >::Local.

◆ GetEmbedderData()

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.

Definition at line 10473 of file v8.h.

References Local< T >::Local, and Internals::ReadEmbedderData().

◆ GetExtrasBindingObject()

Local<Object> GetExtrasBindingObject ( )

Gets the binding object used by V8 extras. Extra natives get a reference to this object and can use it to "export" functionality by adding properties. Extra natives can also "import" functionality by accessing properties added by the embedder using the V8 API.

◆ GetIsolate()

Isolate* GetIsolate ( )

Returns an isolate associated with a current context.

◆ GetNumberOfEmbedderDataFields()

uint32_t GetNumberOfEmbedderDataFields ( )

Return the number of fields allocated for embedder data.

◆ GetSecurityToken()

Local<Value> GetSecurityToken ( )

Returns the security token of this 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.

◆ IsCodeGenerationFromStringsAllowed()

bool IsCodeGenerationFromStringsAllowed ( )

Returns true if code generation from strings is allowed for the context. For more details see AllowCodeGenerationFromStrings(bool) documentation.

◆ New()

static Local<Context> New ( Isolate isolate,
ExtensionConfiguration extensions = NULL,
MaybeLocal< ObjectTemplate global_template = MaybeLocalObjectTemplate >(),
MaybeLocal< Value global_object = MaybeLocalValue >(),
DeserializeInternalFieldsCallback  internal_fields_deserializer = DeserializeInternalFieldsCallback() 

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

isolateThe isolate in which to create the context.
extensionsAn optional extension configuration containing the extensions to be installed in the newly created context.
global_templateAn optional object template from which the global object for the newly created context will be created.
global_objectAn 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.

◆ NewRemoteContext()

static MaybeLocal<Object> NewRemoteContext ( Isolate isolate,
Local< ObjectTemplate global_template,
MaybeLocal< Value global_object = MaybeLocalValue >() 

Returns an global object that isn't backed by an actual context.

The global template needs to have access checks with handlers installed. If an existing global object is passed in, the global object is detached from its context.

Note that this is different from a detached context where all accesses to the global proxy will fail. Instead, the access check handlers are invoked.

It is also not possible to detach an object returned by this method. Instead, the access check handlers need to return nothing to achieve the same effect.

It is possible, however, to create a new context from the global object returned by this method.

◆ SetAlignedPointerInEmbedderData()

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

◆ SetEmbedderData()

void SetEmbedderData ( int  index,
Local< 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.

◆ SetErrorMessageForCodeGenerationFromStrings()

void SetErrorMessageForCodeGenerationFromStrings ( Local< 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.

◆ SetSecurityToken()

void SetSecurityToken ( Local< Value token)

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

◆ UseDefaultSecurityToken()

void UseDefaultSecurityToken ( )

Restores the security token to the default value.

Friends And Related Function Documentation

◆ Function

friend class Function

Definition at line 9000 of file v8.h.

◆ Object

friend class Object

Definition at line 8999 of file v8.h.

◆ Script

friend class Script

Definition at line 8998 of file v8.h.

◆ Value

friend class Value

Definition at line 8997 of file v8.h.

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