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// Copyright 2014 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_STRING_BUILDER_INL_H_
#define V8_STRING_BUILDER_INL_H_
#include "src/assert-scope.h"
#include "src/handles-inl.h"
#include "src/heap/factory.h"
#include "src/isolate.h"
#include "src/objects.h"
#include "src/objects/fixed-array.h"
#include "src/objects/string-inl.h"
#include "src/utils.h"
namespace v8 {
namespace internal {
const int kStringBuilderConcatHelperLengthBits = 11;
const int kStringBuilderConcatHelperPositionBits = 19;
typedef BitField<int, 0, kStringBuilderConcatHelperLengthBits>
StringBuilderSubstringLength;
typedef BitField<int, kStringBuilderConcatHelperLengthBits,
kStringBuilderConcatHelperPositionBits>
StringBuilderSubstringPosition;
template <typename sinkchar>
void StringBuilderConcatHelper(String special, sinkchar* sink,
FixedArray fixed_array, int array_length);
// Returns the result length of the concatenation.
// On illegal argument, -1 is returned.
int StringBuilderConcatLength(int special_length, FixedArray fixed_array,
int array_length, bool* one_byte);
class FixedArrayBuilder {
public:
explicit FixedArrayBuilder(Isolate* isolate, int initial_capacity);
explicit FixedArrayBuilder(Handle<FixedArray> backing_store);
bool HasCapacity(int elements);
void EnsureCapacity(Isolate* isolate, int elements);
void Add(Object value);
void Add(Smi value);
Handle<FixedArray> array() { return array_; }
int length() { return length_; }
int capacity();
Handle<JSArray> ToJSArray(Handle<JSArray> target_array);
private:
Handle<FixedArray> array_;
int length_;
bool has_non_smi_elements_;
};
class ReplacementStringBuilder {
public:
ReplacementStringBuilder(Heap* heap, Handle<String> subject,
int estimated_part_count);
static inline void AddSubjectSlice(FixedArrayBuilder* builder, int from,
int to) {
DCHECK_GE(from, 0);
int length = to - from;
DCHECK_GT(length, 0);
if (StringBuilderSubstringLength::is_valid(length) &&
StringBuilderSubstringPosition::is_valid(from)) {
int encoded_slice = StringBuilderSubstringLength::encode(length) |
StringBuilderSubstringPosition::encode(from);
builder->Add(Smi::FromInt(encoded_slice));
} else {
// Otherwise encode as two smis.
builder->Add(Smi::FromInt(-length));
builder->Add(Smi::FromInt(from));
}
}
void EnsureCapacity(int elements);
void AddSubjectSlice(int from, int to) {
AddSubjectSlice(&array_builder_, from, to);
IncrementCharacterCount(to - from);
}
void AddString(Handle<String> string);
MaybeHandle<String> ToString();
void IncrementCharacterCount(int by) {
if (character_count_ > String::kMaxLength - by) {
STATIC_ASSERT(String::kMaxLength < kMaxInt);
character_count_ = kMaxInt;
} else {
character_count_ += by;
}
}
private:
void AddElement(Object element);
Heap* heap_;
FixedArrayBuilder array_builder_;
Handle<String> subject_;
int character_count_;
bool is_one_byte_;
};
class IncrementalStringBuilder {
public:
explicit IncrementalStringBuilder(Isolate* isolate);
V8_INLINE String::Encoding CurrentEncoding() { return encoding_; }
template <typename SrcChar, typename DestChar>
V8_INLINE void Append(SrcChar c);
V8_INLINE void AppendCharacter(uint8_t c) {
if (encoding_ == String::ONE_BYTE_ENCODING) {
Append<uint8_t, uint8_t>(c);
} else {
Append<uint8_t, uc16>(c);
}
}
V8_INLINE void AppendCString(const char* s) {
const uint8_t* u = reinterpret_cast<const uint8_t*>(s);
if (encoding_ == String::ONE_BYTE_ENCODING) {
while (*u != '\0') Append<uint8_t, uint8_t>(*(u++));
} else {
while (*u != '\0') Append<uint8_t, uc16>(*(u++));
}
}
V8_INLINE void AppendCString(const uc16* s) {
if (encoding_ == String::ONE_BYTE_ENCODING) {
while (*s != '\0') Append<uc16, uint8_t>(*(s++));
} else {
while (*s != '\0') Append<uc16, uc16>(*(s++));
}
}
V8_INLINE bool CurrentPartCanFit(int length) {
return part_length_ - current_index_ > length;
}
// We make a rough estimate to find out if the current string can be
// serialized without allocating a new string part. The worst case length of
// an escaped character is 6. Shifting the remaining string length right by 3
// is a more pessimistic estimate, but faster to calculate.
V8_INLINE int EscapedLengthIfCurrentPartFits(int length) {
if (length > kMaxPartLength) return 0;
STATIC_ASSERT((kMaxPartLength << 3) <= String::kMaxLength);
// This shift will not overflow because length is already less than the
// maximum part length.
int worst_case_length = length << 3;
return CurrentPartCanFit(worst_case_length) ? worst_case_length : 0;
}
void AppendString(Handle<String> string);
MaybeHandle<String> Finish();
V8_INLINE bool HasOverflowed() const { return overflowed_; }
int Length() const;
// Change encoding to two-byte.
void ChangeEncoding() {
DCHECK_EQ(String::ONE_BYTE_ENCODING, encoding_);
ShrinkCurrentPart();
encoding_ = String::TWO_BYTE_ENCODING;
Extend();
}
template <typename DestChar>
class NoExtend {
public:
NoExtend(Handle<String> string, int offset,
const DisallowHeapAllocation& no_gc) {
DCHECK(string->IsSeqOneByteString() || string->IsSeqTwoByteString());
if (sizeof(DestChar) == 1) {
start_ = reinterpret_cast<DestChar*>(
Handle<SeqOneByteString>::cast(string)->GetChars(no_gc) + offset);
} else {
start_ = reinterpret_cast<DestChar*>(
Handle<SeqTwoByteString>::cast(string)->GetChars(no_gc) + offset);
}
cursor_ = start_;
}
V8_INLINE void Append(DestChar c) { *(cursor_++) = c; }
V8_INLINE void AppendCString(const char* s) {
const uint8_t* u = reinterpret_cast<const uint8_t*>(s);
while (*u != '\0') Append(*(u++));
}
int written() { return static_cast<int>(cursor_ - start_); }
private:
DestChar* start_;
DestChar* cursor_;
DISALLOW_HEAP_ALLOCATION(no_gc_);
};
template <typename DestChar>
class NoExtendString : public NoExtend<DestChar> {
public:
NoExtendString(Handle<String> string, int required_length)
: NoExtend<DestChar>(string, 0), string_(string) {
DCHECK(string->length() >= required_length);
}
Handle<String> Finalize() {
Handle<SeqString> string = Handle<SeqString>::cast(string_);
int length = NoExtend<DestChar>::written();
Handle<String> result = SeqString::Truncate(string, length);
string_ = Handle<String>();
return result;
}
private:
Handle<String> string_;
};
template <typename DestChar>
class NoExtendBuilder : public NoExtend<DestChar> {
public:
NoExtendBuilder(IncrementalStringBuilder* builder, int required_length,
const DisallowHeapAllocation& no_gc)
: NoExtend<DestChar>(builder->current_part(), builder->current_index_,
no_gc),
builder_(builder) {
DCHECK(builder->CurrentPartCanFit(required_length));
}
~NoExtendBuilder() {
builder_->current_index_ += NoExtend<DestChar>::written();
}
private:
IncrementalStringBuilder* builder_;
};
private:
Factory* factory() { return isolate_->factory(); }
V8_INLINE Handle<String> accumulator() { return accumulator_; }
V8_INLINE void set_accumulator(Handle<String> string) {
*accumulator_.location() = string->ptr();
}
V8_INLINE Handle<String> current_part() { return current_part_; }
V8_INLINE void set_current_part(Handle<String> string) {
*current_part_.location() = string->ptr();
}
// Add the current part to the accumulator.
void Accumulate(Handle<String> new_part);
// Finish the current part and allocate a new part.
void Extend();
// Shrink current part to the right size.
void ShrinkCurrentPart() {
DCHECK(current_index_ < part_length_);
set_current_part(SeqString::Truncate(
Handle<SeqString>::cast(current_part()), current_index_));
}
static const int kInitialPartLength = 32;
static const int kMaxPartLength = 16 * 1024;
static const int kPartLengthGrowthFactor = 2;
Isolate* isolate_;
String::Encoding encoding_;
bool overflowed_;
int part_length_;
int current_index_;
Handle<String> accumulator_;
Handle<String> current_part_;
};
template <typename SrcChar, typename DestChar>
void IncrementalStringBuilder::Append(SrcChar c) {
DCHECK_EQ(encoding_ == String::ONE_BYTE_ENCODING, sizeof(DestChar) == 1);
if (sizeof(DestChar) == 1) {
DCHECK_EQ(String::ONE_BYTE_ENCODING, encoding_);
SeqOneByteString::cast(*current_part_)
->SeqOneByteStringSet(current_index_++, c);
} else {
DCHECK_EQ(String::TWO_BYTE_ENCODING, encoding_);
SeqTwoByteString::cast(*current_part_)
->SeqTwoByteStringSet(current_index_++, c);
}
if (current_index_ == part_length_) Extend();
}
} // namespace internal
} // namespace v8
#endif // V8_STRING_BUILDER_INL_H_