// Copyright 2025 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.

#include "src/regexp/regexp-bytecode-iterator.h"

#include "src/objects/fixed-array-inl.h"

#include "src/regexp/regexp-bytecode-iterator-inl.h"

#include "src/regexp/regexp-bytecodes-inl.h"

namespace v8 {

namespace internal {

RegExpBytecodeIterator::RegExpBytecodeIterator(

DirectHandle<TrustedByteArray> bytecode)

: RegExpBytecodeIterator(bytecode, 0) {}

RegExpBytecodeIterator::RegExpBytecodeIterator(

DirectHandle<TrustedByteArray> bytecode, int offset)

: bytecode_(bytecode),

start_(bytecode->begin()),

end_(bytecode->end()),

cursor_(start_ + offset) {

Isolate::Current()->main_thread_local_heap()->AddGCEpilogueCallback(

UpdatePointersCallback, this);

#ifdef DEBUG

if (V8_UNLIKELY(v8_flags.enable_slow_asserts)) {

DCHECK_GE(offset, 0);

DCHECK_LT(offset, bytecode->length());

const uint8_t* start_with_offset = cursor_;

cursor_ = start_;

while (cursor_ < start_with_offset) advance();

// `offset` must not point into the middle of a bytecode.

DCHECK_EQ(cursor_, start_with_offset);

}

#endif // DEBUG

}

RegExpBytecodeIterator::~RegExpBytecodeIterator() {

Isolate::Current()->main_thread_local_heap()->RemoveGCEpilogueCallback(

UpdatePointersCallback, this);

}

// static

void RegExpBytecodeIterator::UpdatePointersCallback(void* iterator) {

reinterpret_cast<RegExpBytecodeIterator*>(iterator)->UpdatePointers();

}

void RegExpBytecodeIterator::UpdatePointers() {

DisallowGarbageCollection no_gc;

uint8_t* start = bytecode_->begin();

if (start != start_) {

start_ = start;

uint8_t* end = bytecode_->end();

size_t distance_to_end = end_ - cursor_;

cursor_ = end - distance_to_end;

end_ = end;

}

}

} // namespace internal

} // namespace v8