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| 1 // Copyright 2012 the V8 project authors. All rights reserved. | 1 // Copyright 2012 the V8 project authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 #ifndef V8_UTILS_H_ | 5 #ifndef V8_UTILS_H_ |
| 6 #define V8_UTILS_H_ | 6 #define V8_UTILS_H_ |
| 7 | 7 |
| 8 #include <limits.h> | 8 #include <limits.h> |
| 9 #include <stdlib.h> | 9 #include <stdlib.h> |
| 10 #include <string.h> | 10 #include <string.h> |
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| 541 Vector<T>::operator=(rhs); | 541 Vector<T>::operator=(rhs); |
| 542 MemCopy(buffer_, rhs.buffer_, sizeof(T) * kSize); | 542 MemCopy(buffer_, rhs.buffer_, sizeof(T) * kSize); |
| 543 this->set_start(buffer_); | 543 this->set_start(buffer_); |
| 544 return *this; | 544 return *this; |
| 545 } | 545 } |
| 546 | 546 |
| 547 private: | 547 private: |
| 548 T buffer_[kSize]; | 548 T buffer_[kSize]; |
| 549 }; | 549 }; |
| 550 | 550 |
| 551 | |
| 552 /* | |
| 553 * A class that collects values into a backing store. | |
| 554 * Specialized versions of the class can allow access to the backing store | |
| 555 * in different ways. | |
| 556 * There is no guarantee that the backing store is contiguous (and, as a | |
| 557 * consequence, no guarantees that consecutively added elements are adjacent | |
| 558 * in memory). The collector may move elements unless it has guaranteed not | |
| 559 * to. | |
| 560 */ | |
| 561 template <typename T, int growth_factor = 2, int max_growth = 1 * MB> | |
| 562 class Collector { | |
| 563 public: | |
| 564 explicit Collector(int initial_capacity = kMinCapacity) | |
| 565 : index_(0), size_(0) { | |
| 566 current_chunk_ = Vector<T>::New(initial_capacity); | |
| 567 } | |
| 568 | |
| 569 virtual ~Collector() { | |
| 570 // Free backing store (in reverse allocation order). | |
| 571 current_chunk_.Dispose(); | |
| 572 for (int i = chunks_.length() - 1; i >= 0; i--) { | |
| 573 chunks_.at(i).Dispose(); | |
| 574 } | |
| 575 } | |
| 576 | |
| 577 // Add a single element. | |
| 578 inline void Add(T value) { | |
| 579 if (index_ >= current_chunk_.length()) { | |
| 580 Grow(1); | |
| 581 } | |
| 582 current_chunk_[index_] = value; | |
| 583 index_++; | |
| 584 size_++; | |
| 585 } | |
| 586 | |
| 587 // Add a block of contiguous elements and return a Vector backed by the | |
| 588 // memory area. | |
| 589 // A basic Collector will keep this vector valid as long as the Collector | |
| 590 // is alive. | |
| 591 inline Vector<T> AddBlock(int size, T initial_value) { | |
| 592 DCHECK(size > 0); | |
| 593 if (size > current_chunk_.length() - index_) { | |
| 594 Grow(size); | |
| 595 } | |
| 596 T* position = current_chunk_.start() + index_; | |
| 597 index_ += size; | |
| 598 size_ += size; | |
| 599 for (int i = 0; i < size; i++) { | |
| 600 position[i] = initial_value; | |
| 601 } | |
| 602 return Vector<T>(position, size); | |
| 603 } | |
| 604 | |
| 605 | |
| 606 // Add a contiguous block of elements and return a vector backed | |
| 607 // by the added block. | |
| 608 // A basic Collector will keep this vector valid as long as the Collector | |
| 609 // is alive. | |
| 610 inline Vector<T> AddBlock(Vector<const T> source) { | |
| 611 if (source.length() > current_chunk_.length() - index_) { | |
| 612 Grow(source.length()); | |
| 613 } | |
| 614 T* position = current_chunk_.start() + index_; | |
| 615 index_ += source.length(); | |
| 616 size_ += source.length(); | |
| 617 for (int i = 0; i < source.length(); i++) { | |
| 618 position[i] = source[i]; | |
| 619 } | |
| 620 return Vector<T>(position, source.length()); | |
| 621 } | |
| 622 | |
| 623 | |
| 624 // Write the contents of the collector into the provided vector. | |
| 625 void WriteTo(Vector<T> destination) { | |
| 626 DCHECK(size_ <= destination.length()); | |
| 627 int position = 0; | |
| 628 for (int i = 0; i < chunks_.length(); i++) { | |
| 629 Vector<T> chunk = chunks_.at(i); | |
| 630 for (int j = 0; j < chunk.length(); j++) { | |
| 631 destination[position] = chunk[j]; | |
| 632 position++; | |
| 633 } | |
| 634 } | |
| 635 for (int i = 0; i < index_; i++) { | |
| 636 destination[position] = current_chunk_[i]; | |
| 637 position++; | |
| 638 } | |
| 639 } | |
| 640 | |
| 641 // Allocate a single contiguous vector, copy all the collected | |
| 642 // elements to the vector, and return it. | |
| 643 // The caller is responsible for freeing the memory of the returned | |
| 644 // vector (e.g., using Vector::Dispose). | |
| 645 Vector<T> ToVector() { | |
| 646 Vector<T> new_store = Vector<T>::New(size_); | |
| 647 WriteTo(new_store); | |
| 648 return new_store; | |
| 649 } | |
| 650 | |
| 651 // Resets the collector to be empty. | |
| 652 virtual void Reset() { | |
| 653 for (int i = chunks_.length() - 1; i >= 0; i--) { | |
| 654 chunks_.at(i).Dispose(); | |
| 655 } | |
| 656 chunks_.Rewind(0); | |
| 657 index_ = 0; | |
| 658 size_ = 0; | |
| 659 } | |
| 660 | |
| 661 // Total number of elements added to collector so far. | |
| 662 inline int size() { return size_; } | |
| 663 | |
| 664 protected: | |
| 665 static const int kMinCapacity = 16; | |
| 666 List<Vector<T> > chunks_; | |
| 667 Vector<T> current_chunk_; // Block of memory currently being written into. | |
| 668 int index_; // Current index in current chunk. | |
| 669 int size_; // Total number of elements in collector. | |
| 670 | |
| 671 // Creates a new current chunk, and stores the old chunk in the chunks_ list. | |
| 672 void Grow(int min_capacity) { | |
| 673 DCHECK(growth_factor > 1); | |
| 674 int new_capacity; | |
| 675 int current_length = current_chunk_.length(); | |
| 676 if (current_length < kMinCapacity) { | |
| 677 // The collector started out as empty. | |
| 678 new_capacity = min_capacity * growth_factor; | |
| 679 if (new_capacity < kMinCapacity) new_capacity = kMinCapacity; | |
| 680 } else { | |
| 681 int growth = current_length * (growth_factor - 1); | |
| 682 if (growth > max_growth) { | |
| 683 growth = max_growth; | |
| 684 } | |
| 685 new_capacity = current_length + growth; | |
| 686 if (new_capacity < min_capacity) { | |
| 687 new_capacity = min_capacity + growth; | |
| 688 } | |
| 689 } | |
| 690 NewChunk(new_capacity); | |
| 691 DCHECK(index_ + min_capacity <= current_chunk_.length()); | |
| 692 } | |
| 693 | |
| 694 // Before replacing the current chunk, give a subclass the option to move | |
| 695 // some of the current data into the new chunk. The function may update | |
| 696 // the current index_ value to represent data no longer in the current chunk. | |
| 697 // Returns the initial index of the new chunk (after copied data). | |
| 698 virtual void NewChunk(int new_capacity) { | |
| 699 Vector<T> new_chunk = Vector<T>::New(new_capacity); | |
| 700 if (index_ > 0) { | |
| 701 chunks_.Add(current_chunk_.SubVector(0, index_)); | |
| 702 } else { | |
| 703 current_chunk_.Dispose(); | |
| 704 } | |
| 705 current_chunk_ = new_chunk; | |
| 706 index_ = 0; | |
| 707 } | |
| 708 }; | |
| 709 | |
| 710 | |
| 711 /* | |
| 712 * A collector that allows sequences of values to be guaranteed to | |
| 713 * stay consecutive. | |
| 714 * If the backing store grows while a sequence is active, the current | |
| 715 * sequence might be moved, but after the sequence is ended, it will | |
| 716 * not move again. | |
| 717 * NOTICE: Blocks allocated using Collector::AddBlock(int) can move | |
| 718 * as well, if inside an active sequence where another element is added. | |
| 719 */ | |
| 720 template <typename T, int growth_factor = 2, int max_growth = 1 * MB> | |
| 721 class SequenceCollector : public Collector<T, growth_factor, max_growth> { | |
| 722 public: | |
| 723 explicit SequenceCollector(int initial_capacity) | |
| 724 : Collector<T, growth_factor, max_growth>(initial_capacity), | |
| 725 sequence_start_(kNoSequence) { } | |
| 726 | |
| 727 virtual ~SequenceCollector() {} | |
| 728 | |
| 729 void StartSequence() { | |
| 730 DCHECK(sequence_start_ == kNoSequence); | |
| 731 sequence_start_ = this->index_; | |
| 732 } | |
| 733 | |
| 734 Vector<T> EndSequence() { | |
| 735 DCHECK(sequence_start_ != kNoSequence); | |
| 736 int sequence_start = sequence_start_; | |
| 737 sequence_start_ = kNoSequence; | |
| 738 if (sequence_start == this->index_) return Vector<T>(); | |
| 739 return this->current_chunk_.SubVector(sequence_start, this->index_); | |
| 740 } | |
| 741 | |
| 742 // Drops the currently added sequence, and all collected elements in it. | |
| 743 void DropSequence() { | |
| 744 DCHECK(sequence_start_ != kNoSequence); | |
| 745 int sequence_length = this->index_ - sequence_start_; | |
| 746 this->index_ = sequence_start_; | |
| 747 this->size_ -= sequence_length; | |
| 748 sequence_start_ = kNoSequence; | |
| 749 } | |
| 750 | |
| 751 virtual void Reset() { | |
| 752 sequence_start_ = kNoSequence; | |
| 753 this->Collector<T, growth_factor, max_growth>::Reset(); | |
| 754 } | |
| 755 | |
| 756 private: | |
| 757 static const int kNoSequence = -1; | |
| 758 int sequence_start_; | |
| 759 | |
| 760 // Move the currently active sequence to the new chunk. | |
| 761 virtual void NewChunk(int new_capacity) { | |
| 762 if (sequence_start_ == kNoSequence) { | |
| 763 // Fall back on default behavior if no sequence has been started. | |
| 764 this->Collector<T, growth_factor, max_growth>::NewChunk(new_capacity); | |
| 765 return; | |
| 766 } | |
| 767 int sequence_length = this->index_ - sequence_start_; | |
| 768 Vector<T> new_chunk = Vector<T>::New(sequence_length + new_capacity); | |
| 769 DCHECK(sequence_length < new_chunk.length()); | |
| 770 for (int i = 0; i < sequence_length; i++) { | |
| 771 new_chunk[i] = this->current_chunk_[sequence_start_ + i]; | |
| 772 } | |
| 773 if (sequence_start_ > 0) { | |
| 774 this->chunks_.Add(this->current_chunk_.SubVector(0, sequence_start_)); | |
| 775 } else { | |
| 776 this->current_chunk_.Dispose(); | |
| 777 } | |
| 778 this->current_chunk_ = new_chunk; | |
| 779 this->index_ = sequence_length; | |
| 780 sequence_start_ = 0; | |
| 781 } | |
| 782 }; | |
| 783 | |
| 784 | |
| 785 // Compare 8bit/16bit chars to 8bit/16bit chars. | 551 // Compare 8bit/16bit chars to 8bit/16bit chars. |
| 786 template <typename lchar, typename rchar> | 552 template <typename lchar, typename rchar> |
| 787 inline int CompareCharsUnsigned(const lchar* lhs, const rchar* rhs, | 553 inline int CompareCharsUnsigned(const lchar* lhs, const rchar* rhs, |
| 788 size_t chars) { | 554 size_t chars) { |
| 789 const lchar* limit = lhs + chars; | 555 const lchar* limit = lhs + chars; |
| 790 if (sizeof(*lhs) == sizeof(char) && sizeof(*rhs) == sizeof(char)) { | 556 if (sizeof(*lhs) == sizeof(char) && sizeof(*rhs) == sizeof(char)) { |
| 791 // memcmp compares byte-by-byte, yielding wrong results for two-byte | 557 // memcmp compares byte-by-byte, yielding wrong results for two-byte |
| 792 // strings on little-endian systems. | 558 // strings on little-endian systems. |
| 793 return memcmp(lhs, rhs, chars); | 559 return memcmp(lhs, rhs, chars); |
| 794 } | 560 } |
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| 1769 } | 1535 } |
| 1770 | 1536 |
| 1771 static inline void WriteUnalignedUInt32(void* p, uint32_t value) { | 1537 static inline void WriteUnalignedUInt32(void* p, uint32_t value) { |
| 1772 WriteUnalignedValue(p, value); | 1538 WriteUnalignedValue(p, value); |
| 1773 } | 1539 } |
| 1774 | 1540 |
| 1775 } // namespace internal | 1541 } // namespace internal |
| 1776 } // namespace v8 | 1542 } // namespace v8 |
| 1777 | 1543 |
| 1778 #endif // V8_UTILS_H_ | 1544 #endif // V8_UTILS_H_ |
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