v8  8.6.395 (node 15.0.1)
V8 is Google's open source JavaScript engine
String Class Reference

#include <v8.h>

Inheritance diagram for String:
Collaboration diagram for String:

Data Structures

class  ExternalOneByteStringResource
 
class  ExternalStringResource
 
class  ExternalStringResourceBase
 
class  Utf8Value
 
class  Value
 

Public Types

enum  Encoding { UNKNOWN_ENCODING = 0x1 , TWO_BYTE_ENCODING = 0x0 , ONE_BYTE_ENCODING = 0x8 }
 
enum  WriteOptions {
  NO_OPTIONS = 0 , HINT_MANY_WRITES_EXPECTED = 1 , NO_NULL_TERMINATION = 2 , PRESERVE_ONE_BYTE_NULL = 4 ,
  REPLACE_INVALID_UTF8 = 8
}
 

Public Member Functions

int Length () const
 
int Utf8Length (Isolate *isolate) const
 
bool IsOneByte () const
 
bool ContainsOnlyOneByte () const
 
int Write (Isolate *isolate, uint16_t *buffer, int start=0, int length=-1, int options=NO_OPTIONS) const
 
int WriteOneByte (Isolate *isolate, uint8_t *buffer, int start=0, int length=-1, int options=NO_OPTIONS) const
 
int WriteUtf8 (Isolate *isolate, char *buffer, int length=-1, int *nchars_ref=nullptr, int options=NO_OPTIONS) const
 
bool IsExternal () const
 
bool IsExternalOneByte () const
 
V8_INLINE ExternalStringResourceBaseGetExternalStringResourceBase (Encoding *encoding_out) const
 
V8_INLINE ExternalStringResourceGetExternalStringResource () const
 
const ExternalOneByteStringResourceGetExternalOneByteStringResource () const
 
bool MakeExternal (ExternalStringResource *resource)
 
bool MakeExternal (ExternalOneByteStringResource *resource)
 
bool CanMakeExternal ()
 
bool StringEquals (Local< String > str)
 
template<>
V8_WARN_UNUSED_RESULT Local< StringNewFromUtf8Literal (Isolate *isolate, const char(&literal)[1], NewStringType type)
 
- Public Member Functions inherited from Name
int GetIdentityHash ()
 
- Public Member Functions inherited from Value
V8_INLINE bool IsUndefined () const
 
V8_INLINE bool IsNull () const
 
V8_INLINE bool IsNullOrUndefined () const
 
bool IsTrue () const
 
bool IsFalse () const
 
bool IsName () const
 
V8_INLINE bool IsString () const
 
bool IsSymbol () const
 
bool IsFunction () const
 
bool IsArray () const
 
bool IsObject () const
 
bool IsBigInt () const
 
bool IsBoolean () const
 
bool IsNumber () const
 
bool IsExternal () const
 
bool IsInt32 () const
 
bool IsUint32 () const
 
bool IsDate () const
 
bool IsArgumentsObject () const
 
bool IsBigIntObject () const
 
bool IsBooleanObject () const
 
bool IsNumberObject () const
 
bool IsStringObject () const
 
bool IsSymbolObject () const
 
bool IsNativeError () const
 
bool IsRegExp () const
 
bool IsAsyncFunction () const
 
bool IsGeneratorFunction () const
 
bool IsGeneratorObject () const
 
bool IsPromise () const
 
bool IsMap () const
 
bool IsSet () const
 
bool IsMapIterator () const
 
bool IsSetIterator () const
 
bool IsWeakMap () const
 
bool IsWeakSet () const
 
bool IsArrayBuffer () const
 
bool IsArrayBufferView () const
 
bool IsTypedArray () const
 
bool IsUint8Array () const
 
bool IsUint8ClampedArray () const
 
bool IsInt8Array () const
 
bool IsUint16Array () const
 
bool IsInt16Array () const
 
bool IsUint32Array () const
 
bool IsInt32Array () const
 
bool IsFloat32Array () const
 
bool IsFloat64Array () const
 
bool IsBigInt64Array () const
 
bool IsBigUint64Array () const
 
bool IsDataView () const
 
bool IsSharedArrayBuffer () const
 
bool IsProxy () const
 
bool IsWasmModuleObject () const
 
bool IsModuleNamespaceObject () const
 
V8_WARN_UNUSED_RESULT MaybeLocal< BigIntToBigInt (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< NumberToNumber (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< StringToString (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< StringToDetailString (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< ObjectToObject (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< IntegerToInteger (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< Uint32ToUint32 (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< Int32ToInt32 (Local< Context > context) const
 
Local< BooleanToBoolean (Isolate *isolate) const
 
V8_WARN_UNUSED_RESULT MaybeLocal< Uint32ToArrayIndex (Local< Context > context) const
 
bool BooleanValue (Isolate *isolate) const
 
V8_WARN_UNUSED_RESULT Maybe< double > NumberValue (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT Maybe< int64_t > IntegerValue (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT Maybe< uint32_t > Uint32Value (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT Maybe< int32_t > Int32Value (Local< Context > context) const
 
V8_WARN_UNUSED_RESULT Maybe< bool > Equals (Local< Context > context, Local< Value > that) const
 
bool StrictEquals (Local< Value > that) const
 
bool SameValue (Local< Value > that) const
 
Local< StringTypeOf (Isolate *)
 
Maybe< bool > InstanceOf (Local< Context > context, Local< Object > object)
 
template<class T >
ValueCast (T *value)
 

Static Public Member Functions

static V8_INLINE Local< StringEmpty (Isolate *isolate)
 
static V8_INLINE StringCast (v8::Value *obj)
 
template<int N>
static V8_WARN_UNUSED_RESULT Local< StringNewFromUtf8Literal (Isolate *isolate, const char(&literal)[N], NewStringType type=NewStringType::kNormal)
 
static V8_WARN_UNUSED_RESULT MaybeLocal< StringNewFromUtf8 (Isolate *isolate, const char *data, NewStringType type=NewStringType::kNormal, int length=-1)
 
static V8_WARN_UNUSED_RESULT MaybeLocal< StringNewFromOneByte (Isolate *isolate, const uint8_t *data, NewStringType type=NewStringType::kNormal, int length=-1)
 
static V8_WARN_UNUSED_RESULT MaybeLocal< StringNewFromTwoByte (Isolate *isolate, const uint16_t *data, NewStringType type=NewStringType::kNormal, int length=-1)
 
static Local< StringConcat (Isolate *isolate, Local< String > left, Local< String > right)
 
static V8_WARN_UNUSED_RESULT MaybeLocal< StringNewExternalTwoByte (Isolate *isolate, ExternalStringResource *resource)
 
static V8_WARN_UNUSED_RESULT MaybeLocal< StringNewExternalOneByte (Isolate *isolate, ExternalOneByteStringResource *resource)
 
- Static Public Member Functions inherited from Name
static V8_INLINE NameCast (Value *obj)
 
- Static Public Member Functions inherited from Value
template<class T >
static V8_INLINE ValueCast (T *value)
 

Static Public Attributes

static constexpr int kMaxLength
 

Detailed Description

A JavaScript string value (ECMA-262, 4.3.17).

Definition at line 3002 of file v8.h.

Member Enumeration Documentation

◆ Encoding

enum Encoding
Enumerator
UNKNOWN_ENCODING 
TWO_BYTE_ENCODING 
ONE_BYTE_ENCODING 

Definition at line 3007 of file v8.h.

◆ WriteOptions

Write the contents of the string to an external buffer. If no arguments are given, expects the buffer to be large enough to hold the entire string and NULL terminator. Copies the contents of the string and the NULL terminator into the buffer.

WriteUtf8 will not write partial UTF-8 sequences, preferring to stop before the end of the buffer.

Copies up to length characters into the output buffer. Only null-terminates if there is enough space in the buffer.

Parameters
bufferThe buffer into which the string will be copied.
startThe starting position within the string at which copying begins.
lengthThe number of characters to copy from the string. For WriteUtf8 the number of bytes in the buffer.
nchars_refThe number of characters written, can be NULL.
optionsVarious options that might affect performance of this or subsequent operations.
Returns
The number of characters copied to the buffer excluding the null terminator. For WriteUtf8: The number of bytes copied to the buffer including the null terminator (if written).
Enumerator
NO_OPTIONS 
HINT_MANY_WRITES_EXPECTED 
NO_NULL_TERMINATION 
PRESERVE_ONE_BYTE_NULL 
REPLACE_INVALID_UTF8 

Definition at line 3063 of file v8.h.

Member Function Documentation

◆ CanMakeExternal()

bool CanMakeExternal ( )

Returns true if this string can be made external.

◆ Cast()

String * Cast ( v8::Value obj)
static

Definition at line 11445 of file v8.h.

◆ Concat()

static Local<String> Concat ( Isolate isolate,
Local< String left,
Local< String right 
)
static

Creates a new string by concatenating the left and the right strings passed in as parameters.

◆ ContainsOnlyOneByte()

bool ContainsOnlyOneByte ( ) const

Returns whether this string contain only one byte data, i.e. ISO-8859-1 code points. Will read the entire string in some cases.

◆ Empty()

Local< String > Empty ( Isolate isolate)
static

A zero length string.

Definition at line 11453 of file v8.h.

References Internals::CheckInitialized(), Internals::GetRoot(), Internals::kEmptyStringRootIndex, and Local< T >::Local.

Referenced by String::NewFromUtf8Literal().

◆ GetExternalOneByteStringResource()

const ExternalOneByteStringResource* GetExternalOneByteStringResource ( ) const

Get the ExternalOneByteStringResource for an external one-byte string. Returns NULL if IsExternalOneByte() doesn't return true.

◆ GetExternalStringResource()

String::ExternalStringResource * GetExternalStringResource ( ) const

◆ GetExternalStringResourceBase()

String::ExternalStringResourceBase * GetExternalStringResourceBase ( String::Encoding encoding_out) const

If the string is an external string, return the ExternalStringResourceBase regardless of the encoding, otherwise return NULL. The encoding of the string is returned in encoding_out.

Definition at line 11483 of file v8.h.

References Internals::GetInstanceType(), Internals::GetIsolateForHeapSandbox(), Internals::kExternalOneByteRepresentationTag, Internals::kExternalTwoByteRepresentationTag, Internals::kFullStringRepresentationMask, Internals::kStringEncodingMask, Internals::kStringResourceOffset, and Internals::ReadExternalPointerField().

◆ IsExternal()

bool IsExternal ( ) const

Returns true if the string is external

◆ IsExternalOneByte()

bool IsExternalOneByte ( ) const

Returns true if the string is both external and one-byte.

◆ IsOneByte()

bool IsOneByte ( ) const

Returns whether this string is known to contain only one byte data, i.e. ISO-8859-1 code points. Does not read the string. False negatives are possible.

◆ Length()

int Length ( ) const

Returns the number of characters (UTF-16 code units) in this string.

◆ MakeExternal() [1/2]

bool MakeExternal ( ExternalOneByteStringResource resource)

Associate an external string resource with this string by transforming it in place so that existing references to this string in the JavaScript heap will use the external string resource. The external string resource's character contents need to be equivalent to this string. Returns true if the string has been changed to be an external string. The string is not modified if the operation fails. See NewExternal for information on the lifetime of the resource.

◆ MakeExternal() [2/2]

bool MakeExternal ( ExternalStringResource resource)

Associate an external string resource with this string by transforming it in place so that existing references to this string in the JavaScript heap will use the external string resource. The external string resource's character contents need to be equivalent to this string. Returns true if the string has been changed to be an external string. The string is not modified if the operation fails. See NewExternal for information on the lifetime of the resource.

◆ NewExternalOneByte()

static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewExternalOneByte ( Isolate isolate,
ExternalOneByteStringResource resource 
)
static

Creates a new external string using the one-byte data defined in the given resource. When the external string is no longer live on V8's heap the resource will be disposed by calling its Dispose method. The caller of this function should not otherwise delete or modify the resource. Neither should the underlying buffer be deallocated or modified except through the destructor of the external string resource.

◆ NewExternalTwoByte()

static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewExternalTwoByte ( Isolate isolate,
ExternalStringResource resource 
)
static

Creates a new external string using the data defined in the given resource. When the external string is no longer live on V8's heap the resource will be disposed by calling its Dispose method. The caller of this function should not otherwise delete or modify the resource. Neither should the underlying buffer be deallocated or modified except through the destructor of the external string resource.

◆ NewFromOneByte()

static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromOneByte ( Isolate isolate,
const uint8_t *  data,
NewStringType  type = NewStringType::kNormal,
int  length = -1 
)
static

Allocates a new string from Latin-1 data. Only returns an empty value when length > kMaxLength.

◆ NewFromTwoByte()

static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromTwoByte ( Isolate isolate,
const uint16_t *  data,
NewStringType  type = NewStringType::kNormal,
int  length = -1 
)
static

Allocates a new string from UTF-16 data. Only returns an empty value when length > kMaxLength.

◆ NewFromUtf8()

static V8_WARN_UNUSED_RESULT MaybeLocal<String> NewFromUtf8 ( Isolate isolate,
const char *  data,
NewStringType  type = NewStringType::kNormal,
int  length = -1 
)
static

Allocates a new string from UTF-8 data. Only returns an empty value when length > kMaxLength.

Referenced by Template::Set().

◆ NewFromUtf8Literal() [1/2]

V8_WARN_UNUSED_RESULT Local<String> NewFromUtf8Literal ( Isolate isolate,
const char(&)  literal[1],
NewStringType  type 
)
inline

Definition at line 3387 of file v8.h.

References String::Empty().

◆ NewFromUtf8Literal() [2/2]

static V8_WARN_UNUSED_RESULT Local<String> NewFromUtf8Literal ( Isolate isolate,
const char(&)  literal[N],
NewStringType  type = NewStringType::kNormal 
)
inlinestatic

Allocates a new string from a UTF-8 literal. This is equivalent to calling String::NewFromUtf(isolate, "...").ToLocalChecked(), but without the check overhead.

When called on a string literal containing '\0', the inferred length is the length of the input array minus 1 (for the final '\0') and not the value returned by strlen.

Definition at line 3236 of file v8.h.

References String::kMaxLength.

◆ StringEquals()

bool StringEquals ( Local< String str)

Returns true if the strings values are equal. Same as JS ==/===.

◆ Utf8Length()

int Utf8Length ( Isolate isolate) const

Returns the number of bytes in the UTF-8 encoded representation of this string.

◆ Write()

int Write ( Isolate isolate,
uint16_t *  buffer,
int  start = 0,
int  length = -1,
int  options = NO_OPTIONS 
) const

◆ WriteOneByte()

int WriteOneByte ( Isolate isolate,
uint8_t *  buffer,
int  start = 0,
int  length = -1,
int  options = NO_OPTIONS 
) const

◆ WriteUtf8()

int WriteUtf8 ( Isolate isolate,
char *  buffer,
int  length = -1,
int *  nchars_ref = nullptr,
int  options = NO_OPTIONS 
) const

Field Documentation

◆ kMaxLength

constexpr int kMaxLength
staticconstexpr
Initial value:
=
internal::kApiSystemPointerSize == 4 ? (1 << 28) - 16 : (1 << 29) - 24
const int kApiSystemPointerSize
Definition: v8-internal.h:32

Definition at line 3004 of file v8.h.

Referenced by String::NewFromUtf8Literal().


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