blob: 55e0a365c105a90ca09667c2657911750895c9bc [file] [log] [blame]
// Copyright 2017 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_OBJECTS_STRING_H_
#define V8_OBJECTS_STRING_H_
#include "src/base/bits.h"
#include "src/base/export-template.h"
#include "src/objects/instance-type.h"
#include "src/objects/name.h"
#include "src/objects/smi.h"
#include "src/unicode-decoder.h"
// Has to be the last include (doesn't have include guards):
#include "src/objects/object-macros.h"
namespace v8 {
namespace internal {
enum InstanceType : uint16_t;
enum AllowNullsFlag { ALLOW_NULLS, DISALLOW_NULLS };
enum RobustnessFlag { ROBUST_STRING_TRAVERSAL, FAST_STRING_TRAVERSAL };
// The characteristics of a string are stored in its map. Retrieving these
// few bits of information is moderately expensive, involving two memory
// loads where the second is dependent on the first. To improve efficiency
// the shape of the string is given its own class so that it can be retrieved
// once and used for several string operations. A StringShape is small enough
// to be passed by value and is immutable, but be aware that flattening a
// string can potentially alter its shape. Also be aware that a GC caused by
// something else can alter the shape of a string due to ConsString
// shortcutting. Keeping these restrictions in mind has proven to be error-
// prone and so we no longer put StringShapes in variables unless there is a
// concrete performance benefit at that particular point in the code.
class StringShape {
public:
inline explicit StringShape(const String s);
inline explicit StringShape(Map s);
inline explicit StringShape(InstanceType t);
inline bool IsSequential();
inline bool IsExternal();
inline bool IsCons();
inline bool IsSliced();
inline bool IsThin();
inline bool IsIndirect();
inline bool IsExternalOneByte();
inline bool IsExternalTwoByte();
inline bool IsSequentialOneByte();
inline bool IsSequentialTwoByte();
inline bool IsInternalized();
inline StringRepresentationTag representation_tag();
inline uint32_t encoding_tag();
inline uint32_t full_representation_tag();
#ifdef DEBUG
inline uint32_t type() { return type_; }
inline void invalidate() { valid_ = false; }
inline bool valid() { return valid_; }
#else
inline void invalidate() {}
#endif
private:
uint32_t type_;
#ifdef DEBUG
inline void set_valid() { valid_ = true; }
bool valid_;
#else
inline void set_valid() {}
#endif
};
// The String abstract class captures JavaScript string values:
//
// Ecma-262:
// 4.3.16 String Value
// A string value is a member of the type String and is a finite
// ordered sequence of zero or more 16-bit unsigned integer values.
//
// All string values have a length field.
class String : public Name {
public:
enum Encoding { ONE_BYTE_ENCODING, TWO_BYTE_ENCODING };
// Representation of the flat content of a String.
// A non-flat string doesn't have flat content.
// A flat string has content that's encoded as a sequence of either
// one-byte chars or two-byte UC16.
// Returned by String::GetFlatContent().
class FlatContent {
public:
// Returns true if the string is flat and this structure contains content.
bool IsFlat() const { return state_ != NON_FLAT; }
// Returns true if the structure contains one-byte content.
bool IsOneByte() const { return state_ == ONE_BYTE; }
// Returns true if the structure contains two-byte content.
bool IsTwoByte() const { return state_ == TWO_BYTE; }
// Return the one byte content of the string. Only use if IsOneByte()
// returns true.
Vector<const uint8_t> ToOneByteVector() const {
DCHECK_EQ(ONE_BYTE, state_);
return Vector<const uint8_t>(onebyte_start, length_);
}
// Return the two-byte content of the string. Only use if IsTwoByte()
// returns true.
Vector<const uc16> ToUC16Vector() const {
DCHECK_EQ(TWO_BYTE, state_);
return Vector<const uc16>(twobyte_start, length_);
}
uc16 Get(int i) const {
DCHECK(i < length_);
DCHECK(state_ != NON_FLAT);
if (state_ == ONE_BYTE) return onebyte_start[i];
return twobyte_start[i];
}
bool UsesSameString(const FlatContent& other) const {
return onebyte_start == other.onebyte_start;
}
private:
enum State { NON_FLAT, ONE_BYTE, TWO_BYTE };
// Constructors only used by String::GetFlatContent().
explicit FlatContent(const uint8_t* start, int length)
: onebyte_start(start), length_(length), state_(ONE_BYTE) {}
explicit FlatContent(const uc16* start, int length)
: twobyte_start(start), length_(length), state_(TWO_BYTE) {}
FlatContent() : onebyte_start(nullptr), length_(0), state_(NON_FLAT) {}
union {
const uint8_t* onebyte_start;
const uc16* twobyte_start;
};
int length_;
State state_;
friend class String;
friend class IterableSubString;
};
void MakeThin(Isolate* isolate, String canonical);
template <typename Char>
V8_INLINE Vector<const Char> GetCharVector(
const DisallowHeapAllocation& no_gc);
// Get chars from sequential or external strings.
template <typename Char>
inline const Char* GetChars(const DisallowHeapAllocation& no_gc);
// Get and set the length of the string.
inline int length() const;
inline void set_length(int value);
// Get and set the length of the string using acquire loads and release
// stores.
inline int synchronized_length() const;
inline void synchronized_set_length(int value);
// Returns whether this string has only one-byte chars, i.e. all of them can
// be one-byte encoded. This might be the case even if the string is
// two-byte. Such strings may appear when the embedder prefers
// two-byte external representations even for one-byte data.
inline bool IsOneByteRepresentation() const;
inline bool IsTwoByteRepresentation() const;
// Cons and slices have an encoding flag that may not represent the actual
// encoding of the underlying string. This is taken into account here.
// This function is static because that helps it get inlined.
// Requires: string.IsFlat()
static inline bool IsOneByteRepresentationUnderneath(String string);
// Get and set individual two byte chars in the string.
inline void Set(int index, uint16_t value);
// Get individual two byte char in the string. Repeated calls
// to this method are not efficient unless the string is flat.
V8_INLINE uint16_t Get(int index);
// ES6 section 7.1.3.1 ToNumber Applied to the String Type
static Handle<Object> ToNumber(Isolate* isolate, Handle<String> subject);
// Flattens the string. Checks first inline to see if it is
// necessary. Does nothing if the string is not a cons string.
// Flattening allocates a sequential string with the same data as
// the given string and mutates the cons string to a degenerate
// form, where the first component is the new sequential string and
// the second component is the empty string. If allocation fails,
// this function returns a failure. If flattening succeeds, this
// function returns the sequential string that is now the first
// component of the cons string.
//
// Degenerate cons strings are handled specially by the garbage
// collector (see IsShortcutCandidate).
static inline Handle<String> Flatten(
Isolate* isolate, Handle<String> string,
AllocationType allocation = AllocationType::kYoung);
// Tries to return the content of a flat string as a structure holding either
// a flat vector of char or of uc16.
// If the string isn't flat, and therefore doesn't have flat content, the
// returned structure will report so, and can't provide a vector of either
// kind.
V8_EXPORT_PRIVATE FlatContent
GetFlatContent(const DisallowHeapAllocation& no_gc);
// Returns the parent of a sliced string or first part of a flat cons string.
// Requires: StringShape(this).IsIndirect() && this->IsFlat()
inline String GetUnderlying();
// String relational comparison, implemented according to ES6 section 7.2.11
// Abstract Relational Comparison (step 5): The comparison of Strings uses a
// simple lexicographic ordering on sequences of code unit values. There is no
// attempt to use the more complex, semantically oriented definitions of
// character or string equality and collating order defined in the Unicode
// specification. Therefore String values that are canonically equal according
// to the Unicode standard could test as unequal. In effect this algorithm
// assumes that both Strings are already in normalized form. Also, note that
// for strings containing supplementary characters, lexicographic ordering on
// sequences of UTF-16 code unit values differs from that on sequences of code
// point values.
V8_WARN_UNUSED_RESULT static ComparisonResult Compare(Isolate* isolate,
Handle<String> x,
Handle<String> y);
// Perform ES6 21.1.3.8, including checking arguments.
static Object IndexOf(Isolate* isolate, Handle<Object> receiver,
Handle<Object> search, Handle<Object> position);
// Perform string match of pattern on subject, starting at start index.
// Caller must ensure that 0 <= start_index <= sub->length(), as this does not
// check any arguments.
static int IndexOf(Isolate* isolate, Handle<String> receiver,
Handle<String> search, int start_index);
static Object LastIndexOf(Isolate* isolate, Handle<Object> receiver,
Handle<Object> search, Handle<Object> position);
// Encapsulates logic related to a match and its capture groups as required
// by GetSubstitution.
class Match {
public:
virtual Handle<String> GetMatch() = 0;
virtual Handle<String> GetPrefix() = 0;
virtual Handle<String> GetSuffix() = 0;
// A named capture can be invalid (if it is not specified in the pattern),
// unmatched (specified but not matched in the current string), and matched.
enum CaptureState { INVALID, UNMATCHED, MATCHED };
virtual int CaptureCount() = 0;
virtual bool HasNamedCaptures() = 0;
virtual MaybeHandle<String> GetCapture(int i, bool* capture_exists) = 0;
virtual MaybeHandle<String> GetNamedCapture(Handle<String> name,
CaptureState* state) = 0;
virtual ~Match() = default;
};
// ES#sec-getsubstitution
// GetSubstitution(matched, str, position, captures, replacement)
// Expand the $-expressions in the string and return a new string with
// the result.
// A {start_index} can be passed to specify where to start scanning the
// replacement string.
V8_WARN_UNUSED_RESULT static MaybeHandle<String> GetSubstitution(
Isolate* isolate, Match* match, Handle<String> replacement,
int start_index = 0);
// String equality operations.
inline bool Equals(String other);
inline static bool Equals(Isolate* isolate, Handle<String> one,
Handle<String> two);
// Dispatches to Is{One,Two}ByteEqualTo.
template <typename Char>
bool IsEqualTo(Vector<const Char> str);
V8_EXPORT_PRIVATE bool HasOneBytePrefix(Vector<const char> str);
V8_EXPORT_PRIVATE bool IsOneByteEqualTo(Vector<const uint8_t> str);
V8_EXPORT_PRIVATE bool IsOneByteEqualTo(Vector<const char> str) {
return IsOneByteEqualTo(Vector<const uint8_t>::cast(str));
}
bool IsTwoByteEqualTo(Vector<const uc16> str);
// Return a UTF8 representation of the string. The string is null
// terminated but may optionally contain nulls. Length is returned
// in length_output if length_output is not a null pointer The string
// should be nearly flat, otherwise the performance of this method may
// be very slow (quadratic in the length). Setting robustness_flag to
// ROBUST_STRING_TRAVERSAL invokes behaviour that is robust This means it
// handles unexpected data without causing assert failures and it does not
// do any heap allocations. This is useful when printing stack traces.
std::unique_ptr<char[]> ToCString(AllowNullsFlag allow_nulls,
RobustnessFlag robustness_flag, int offset,
int length, int* length_output = nullptr);
V8_EXPORT_PRIVATE std::unique_ptr<char[]> ToCString(
AllowNullsFlag allow_nulls = DISALLOW_NULLS,
RobustnessFlag robustness_flag = FAST_STRING_TRAVERSAL,
int* length_output = nullptr);
bool ComputeArrayIndex(uint32_t* index);
// Externalization.
V8_EXPORT_PRIVATE bool MakeExternal(
v8::String::ExternalStringResource* resource);
V8_EXPORT_PRIVATE bool MakeExternal(
v8::String::ExternalOneByteStringResource* resource);
bool SupportsExternalization();
// Conversion.
inline bool AsArrayIndex(uint32_t* index);
uint32_t inline ToValidIndex(Object number);
// Trimming.
enum TrimMode { kTrim, kTrimStart, kTrimEnd };
static Handle<String> Trim(Isolate* isolate, Handle<String> string,
TrimMode mode);
DECL_CAST(String)
V8_EXPORT_PRIVATE void PrintOn(FILE* out);
// For use during stack traces. Performs rudimentary sanity check.
bool LooksValid();
// Dispatched behavior.
void StringShortPrint(StringStream* accumulator, bool show_details = true);
void PrintUC16(std::ostream& os, int start = 0, int end = -1); // NOLINT
#if defined(DEBUG) || defined(OBJECT_PRINT)
char* ToAsciiArray();
#endif
DECL_PRINTER(String)
DECL_VERIFIER(String)
inline bool IsFlat();
DEFINE_FIELD_OFFSET_CONSTANTS(Name::kHeaderSize,
TORQUE_GENERATED_STRING_FIELDS)
// Max char codes.
static const int32_t kMaxOneByteCharCode = unibrow::Latin1::kMaxChar;
static const uint32_t kMaxOneByteCharCodeU = unibrow::Latin1::kMaxChar;
static const int kMaxUtf16CodeUnit = 0xffff;
static const uint32_t kMaxUtf16CodeUnitU = kMaxUtf16CodeUnit;
static const uc32 kMaxCodePoint = 0x10ffff;
// Maximal string length.
// The max length is different on 32 and 64 bit platforms. Max length for a
// 32-bit platform is ~268.4M chars. On 64-bit platforms, max length is
// ~1.073B chars. The limit on 64-bit is so that SeqTwoByteString::kMaxSize
// can fit in a 32bit int: 2^31 - 1 is the max positive int, minus one bit as
// each char needs two bytes, subtract 24 bytes for the string header size.
// See include/v8.h for the definition.
static const int kMaxLength = v8::String::kMaxLength;
static_assert(kMaxLength <= (Smi::kMaxValue / 2 - kHeaderSize),
"Unexpected max String length");
// Max length for computing hash. For strings longer than this limit the
// string length is used as the hash value.
static const int kMaxHashCalcLength = 16383;
// Limit for truncation in short printing.
static const int kMaxShortPrintLength = 1024;
// Helper function for flattening strings.
template <typename sinkchar>
EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE)
static void WriteToFlat(String source, sinkchar* sink, int from, int to);
static inline bool IsAscii(const char* chars, int length) {
return IsAscii(reinterpret_cast<const uint8_t*>(chars), length);
}
static inline bool IsAscii(const uint8_t* chars, int length) {
return NonAsciiStart(chars, length) >= length;
}
static inline int NonOneByteStart(const uc16* chars, int length) {
const uc16* limit = chars + length;
const uc16* start = chars;
while (chars < limit) {
if (*chars > kMaxOneByteCharCodeU) return static_cast<int>(chars - start);
++chars;
}
return static_cast<int>(chars - start);
}
static inline bool IsOneByte(const uc16* chars, int length) {
return NonOneByteStart(chars, length) >= length;
}
template <class Visitor>
static inline ConsString VisitFlat(Visitor* visitor, String string,
int offset = 0);
static Handle<FixedArray> CalculateLineEnds(Isolate* isolate,
Handle<String> string,
bool include_ending_line);
private:
friend class Name;
friend class StringTableInsertionKey;
friend class InternalizedStringKey;
V8_EXPORT_PRIVATE static Handle<String> SlowFlatten(
Isolate* isolate, Handle<ConsString> cons, AllocationType allocation);
// Slow case of String::Equals. This implementation works on any strings
// but it is most efficient on strings that are almost flat.
V8_EXPORT_PRIVATE bool SlowEquals(String other);
V8_EXPORT_PRIVATE static bool SlowEquals(Isolate* isolate, Handle<String> one,
Handle<String> two);
// Slow case of AsArrayIndex.
V8_EXPORT_PRIVATE bool SlowAsArrayIndex(uint32_t* index);
// Compute and set the hash code.
V8_EXPORT_PRIVATE uint32_t ComputeAndSetHash();
OBJECT_CONSTRUCTORS(String, Name);
};
// clang-format off
extern template EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE)
void String::WriteToFlat(String source, uint16_t* sink, int from, int to);
// clang-format on
class SubStringRange {
public:
inline SubStringRange(String string, const DisallowHeapAllocation& no_gc,
int first = 0, int length = -1);
class iterator;
inline iterator begin();
inline iterator end();
private:
String string_;
int first_;
int length_;
const DisallowHeapAllocation& no_gc_;
};
// The SeqString abstract class captures sequential string values.
class SeqString : public String {
public:
DECL_CAST(SeqString)
// Truncate the string in-place if possible and return the result.
// In case of new_length == 0, the empty string is returned without
// truncating the original string.
V8_WARN_UNUSED_RESULT static Handle<String> Truncate(Handle<SeqString> string,
int new_length);
OBJECT_CONSTRUCTORS(SeqString, String);
};
class InternalizedString : public String {
public:
DECL_CAST(InternalizedString)
// TODO(neis): Possibly move some stuff from String here.
OBJECT_CONSTRUCTORS(InternalizedString, String);
};
// The OneByteString class captures sequential one-byte string objects.
// Each character in the OneByteString is an one-byte character.
class SeqOneByteString : public SeqString {
public:
static const bool kHasOneByteEncoding = true;
// Dispatched behavior.
inline uint8_t Get(int index);
inline void SeqOneByteStringSet(int index, uint16_t value);
// Get the address of the characters in this string.
inline Address GetCharsAddress();
inline uint8_t* GetChars(const DisallowHeapAllocation& no_gc);
// Clear uninitialized padding space. This ensures that the snapshot content
// is deterministic.
void clear_padding();
DECL_CAST(SeqOneByteString)
// Garbage collection support. This method is called by the
// garbage collector to compute the actual size of an OneByteString
// instance.
inline int SeqOneByteStringSize(InstanceType instance_type);
// Computes the size for an OneByteString instance of a given length.
static int SizeFor(int length) {
return OBJECT_POINTER_ALIGN(kHeaderSize + length * kCharSize);
}
// Maximal memory usage for a single sequential one-byte string.
static const int kMaxCharsSize = kMaxLength;
static const int kMaxSize = OBJECT_POINTER_ALIGN(kMaxCharsSize + kHeaderSize);
STATIC_ASSERT((kMaxSize - kHeaderSize) >= String::kMaxLength);
class BodyDescriptor;
OBJECT_CONSTRUCTORS(SeqOneByteString, SeqString);
};
// The TwoByteString class captures sequential unicode string objects.
// Each character in the TwoByteString is a two-byte uint16_t.
class SeqTwoByteString : public SeqString {
public:
static const bool kHasOneByteEncoding = false;
// Dispatched behavior.
inline uint16_t Get(int index);
inline void SeqTwoByteStringSet(int index, uint16_t value);
// Get the address of the characters in this string.
inline Address GetCharsAddress();
inline uc16* GetChars(const DisallowHeapAllocation& no_gc);
// Clear uninitialized padding space. This ensures that the snapshot content
// is deterministic.
void clear_padding();
DECL_CAST(SeqTwoByteString)
// Garbage collection support. This method is called by the
// garbage collector to compute the actual size of a TwoByteString
// instance.
inline int SeqTwoByteStringSize(InstanceType instance_type);
// Computes the size for a TwoByteString instance of a given length.
static int SizeFor(int length) {
return OBJECT_POINTER_ALIGN(kHeaderSize + length * kShortSize);
}
// Maximal memory usage for a single sequential two-byte string.
static const int kMaxCharsSize = kMaxLength * 2;
static const int kMaxSize = OBJECT_POINTER_ALIGN(kMaxCharsSize + kHeaderSize);
STATIC_ASSERT(static_cast<int>((kMaxSize - kHeaderSize) / sizeof(uint16_t)) >=
String::kMaxLength);
class BodyDescriptor;
OBJECT_CONSTRUCTORS(SeqTwoByteString, SeqString);
};
// The ConsString class describes string values built by using the
// addition operator on strings. A ConsString is a pair where the
// first and second components are pointers to other string values.
// One or both components of a ConsString can be pointers to other
// ConsStrings, creating a binary tree of ConsStrings where the leaves
// are non-ConsString string values. The string value represented by
// a ConsString can be obtained by concatenating the leaf string
// values in a left-to-right depth-first traversal of the tree.
class ConsString : public String {
public:
// First string of the cons cell.
inline String first();
// Doesn't check that the result is a string, even in debug mode. This is
// useful during GC where the mark bits confuse the checks.
inline Object unchecked_first();
inline void set_first(Isolate* isolate, String first,
WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
// Second string of the cons cell.
inline String second();
// Doesn't check that the result is a string, even in debug mode. This is
// useful during GC where the mark bits confuse the checks.
inline Object unchecked_second();
inline void set_second(Isolate* isolate, String second,
WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
// Dispatched behavior.
V8_EXPORT_PRIVATE uint16_t Get(int index);
DECL_CAST(ConsString)
DEFINE_FIELD_OFFSET_CONSTANTS(String::kHeaderSize,
TORQUE_GENERATED_CONS_STRING_FIELDS)
// Minimum length for a cons string.
static const int kMinLength = 13;
using BodyDescriptor = FixedBodyDescriptor<kFirstOffset, kSize, kSize>;
DECL_VERIFIER(ConsString)
OBJECT_CONSTRUCTORS(ConsString, String);
};
// The ThinString class describes string objects that are just references
// to another string object. They are used for in-place internalization when
// the original string cannot actually be internalized in-place: in these
// cases, the original string is converted to a ThinString pointing at its
// internalized version (which is allocated as a new object).
// In terms of memory layout and most algorithms operating on strings,
// ThinStrings can be thought of as "one-part cons strings".
class ThinString : public String {
public:
// Actual string that this ThinString refers to.
inline String actual() const;
inline HeapObject unchecked_actual() const;
inline void set_actual(String s,
WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
V8_EXPORT_PRIVATE uint16_t Get(int index);
DECL_CAST(ThinString)
DECL_VERIFIER(ThinString)
DEFINE_FIELD_OFFSET_CONSTANTS(String::kHeaderSize,
TORQUE_GENERATED_THIN_STRING_FIELDS)
using BodyDescriptor = FixedBodyDescriptor<kActualOffset, kSize, kSize>;
OBJECT_CONSTRUCTORS(ThinString, String);
};
// The Sliced String class describes strings that are substrings of another
// sequential string. The motivation is to save time and memory when creating
// a substring. A Sliced String is described as a pointer to the parent,
// the offset from the start of the parent string and the length. Using
// a Sliced String therefore requires unpacking of the parent string and
// adding the offset to the start address. A substring of a Sliced String
// are not nested since the double indirection is simplified when creating
// such a substring.
// Currently missing features are:
// - handling externalized parent strings
// - external strings as parent
// - truncating sliced string to enable otherwise unneeded parent to be GC'ed.
class SlicedString : public String {
public:
inline String parent();
inline void set_parent(Isolate* isolate, String parent,
WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
inline int offset() const;
inline void set_offset(int offset);
// Dispatched behavior.
V8_EXPORT_PRIVATE uint16_t Get(int index);
DECL_CAST(SlicedString)
DEFINE_FIELD_OFFSET_CONSTANTS(String::kHeaderSize,
TORQUE_GENERATED_SLICED_STRING_FIELDS)
// Minimum length for a sliced string.
static const int kMinLength = 13;
using BodyDescriptor = FixedBodyDescriptor<kParentOffset, kSize, kSize>;
DECL_VERIFIER(SlicedString)
OBJECT_CONSTRUCTORS(SlicedString, String);
};
// The ExternalString class describes string values that are backed by
// a string resource that lies outside the V8 heap. ExternalStrings
// consist of the length field common to all strings, a pointer to the
// external resource. It is important to ensure (externally) that the
// resource is not deallocated while the ExternalString is live in the
// V8 heap.
//
// The API expects that all ExternalStrings are created through the
// API. Therefore, ExternalStrings should not be used internally.
class ExternalString : public String {
public:
DECL_CAST(ExternalString)
DEFINE_FIELD_OFFSET_CONSTANTS(String::kHeaderSize,
TORQUE_GENERATED_EXTERNAL_STRING_FIELDS)
// Size of uncached external strings.
static const int kUncachedSize =
kResourceOffset + FIELD_SIZE(kResourceOffset);
// Return whether the external string data pointer is not cached.
inline bool is_uncached() const;
// Size in bytes of the external payload.
int ExternalPayloadSize() const;
// Used in the serializer/deserializer.
inline Address resource_as_address();
inline void set_address_as_resource(Address address);
inline uint32_t resource_as_uint32();
inline void set_uint32_as_resource(uint32_t value);
// Disposes string's resource object if it has not already been disposed.
inline void DisposeResource();
STATIC_ASSERT(kResourceOffset == Internals::kStringResourceOffset);
static const int kSizeOfAllExternalStrings = kHeaderSize;
OBJECT_CONSTRUCTORS(ExternalString, String);
};
// The ExternalOneByteString class is an external string backed by an
// one-byte string.
class ExternalOneByteString : public ExternalString {
public:
static const bool kHasOneByteEncoding = true;
using Resource = v8::String::ExternalOneByteStringResource;
// The underlying resource.
inline const Resource* resource();
// It is assumed that the previous resource is null. If it is not null, then
// it is the responsability of the caller the handle the previous resource.
inline void SetResource(Isolate* isolate, const Resource* buffer);
// Used only during serialization.
inline void set_resource(const Resource* buffer);
// Update the pointer cache to the external character array.
// The cached pointer is always valid, as the external character array does =
// not move during lifetime. Deserialization is the only exception, after
// which the pointer cache has to be refreshed.
inline void update_data_cache();
inline const uint8_t* GetChars();
// Dispatched behavior.
inline uint8_t Get(int index);
DECL_CAST(ExternalOneByteString)
class BodyDescriptor;
DEFINE_FIELD_OFFSET_CONSTANTS(
ExternalString::kHeaderSize,
TORQUE_GENERATED_EXTERNAL_ONE_BYTE_STRING_FIELDS)
STATIC_ASSERT(kSize == kSizeOfAllExternalStrings);
OBJECT_CONSTRUCTORS(ExternalOneByteString, ExternalString);
};
// The ExternalTwoByteString class is an external string backed by a UTF-16
// encoded string.
class ExternalTwoByteString : public ExternalString {
public:
static const bool kHasOneByteEncoding = false;
using Resource = v8::String::ExternalStringResource;
// The underlying string resource.
inline const Resource* resource();
// It is assumed that the previous resource is null. If it is not null, then
// it is the responsability of the caller the handle the previous resource.
inline void SetResource(Isolate* isolate, const Resource* buffer);
// Used only during serialization.
inline void set_resource(const Resource* buffer);
// Update the pointer cache to the external character array.
// The cached pointer is always valid, as the external character array does =
// not move during lifetime. Deserialization is the only exception, after
// which the pointer cache has to be refreshed.
inline void update_data_cache();
inline const uint16_t* GetChars();
// Dispatched behavior.
inline uint16_t Get(int index);
// For regexp code.
inline const uint16_t* ExternalTwoByteStringGetData(unsigned start);
DECL_CAST(ExternalTwoByteString)
class BodyDescriptor;
DEFINE_FIELD_OFFSET_CONSTANTS(
ExternalString::kHeaderSize,
TORQUE_GENERATED_EXTERNAL_TWO_BYTE_STRING_FIELDS)
STATIC_ASSERT(kSize == kSizeOfAllExternalStrings);
OBJECT_CONSTRUCTORS(ExternalTwoByteString, ExternalString);
};
// A flat string reader provides random access to the contents of a
// string independent of the character width of the string. The handle
// must be valid as long as the reader is being used.
class V8_EXPORT_PRIVATE FlatStringReader : public Relocatable {
public:
FlatStringReader(Isolate* isolate, Handle<String> str);
FlatStringReader(Isolate* isolate, Vector<const char> input);
void PostGarbageCollection() override;
inline uc32 Get(int index);
template <typename Char>
inline Char Get(int index);
int length() { return length_; }
private:
Address* str_;
bool is_one_byte_;
int length_;
const void* start_;
};
// This maintains an off-stack representation of the stack frames required
// to traverse a ConsString, allowing an entirely iterative and restartable
// traversal of the entire string
class ConsStringIterator {
public:
inline ConsStringIterator() = default;
inline explicit ConsStringIterator(ConsString cons_string, int offset = 0) {
Reset(cons_string, offset);
}
inline void Reset(ConsString cons_string, int offset = 0) {
depth_ = 0;
// Next will always return nullptr.
if (cons_string.is_null()) return;
Initialize(cons_string, offset);
}
// Returns nullptr when complete.
inline String Next(int* offset_out) {
*offset_out = 0;
if (depth_ == 0) return String();
return Continue(offset_out);
}
private:
static const int kStackSize = 32;
// Use a mask instead of doing modulo operations for stack wrapping.
static const int kDepthMask = kStackSize - 1;
static_assert(base::bits::IsPowerOfTwo(kStackSize),
"kStackSize must be power of two");
static inline int OffsetForDepth(int depth);
inline void PushLeft(ConsString string);
inline void PushRight(ConsString string);
inline void AdjustMaximumDepth();
inline void Pop();
inline bool StackBlown() { return maximum_depth_ - depth_ == kStackSize; }
V8_EXPORT_PRIVATE void Initialize(ConsString cons_string, int offset);
V8_EXPORT_PRIVATE String Continue(int* offset_out);
String NextLeaf(bool* blew_stack);
String Search(int* offset_out);
// Stack must always contain only frames for which right traversal
// has not yet been performed.
ConsString frames_[kStackSize];
ConsString root_;
int depth_;
int maximum_depth_;
int consumed_;
DISALLOW_COPY_AND_ASSIGN(ConsStringIterator);
};
class StringCharacterStream {
public:
inline explicit StringCharacterStream(String string, int offset = 0);
inline uint16_t GetNext();
inline bool HasMore();
inline void Reset(String string, int offset = 0);
inline void VisitOneByteString(const uint8_t* chars, int length);
inline void VisitTwoByteString(const uint16_t* chars, int length);
private:
ConsStringIterator iter_;
bool is_one_byte_;
union {
const uint8_t* buffer8_;
const uint16_t* buffer16_;
};
const uint8_t* end_;
DISALLOW_COPY_AND_ASSIGN(StringCharacterStream);
};
template <typename Char>
struct CharTraits;
template <>
struct CharTraits<uint8_t> {
using String = SeqOneByteString;
using ExternalString = ExternalOneByteString;
};
template <>
struct CharTraits<uint16_t> {
using String = SeqTwoByteString;
using ExternalString = ExternalTwoByteString;
};
} // namespace internal
} // namespace v8
#include "src/objects/object-macros-undef.h"
#endif // V8_OBJECTS_STRING_H_