| //===- RaggedArray.h - 2D array with different inner lengths ----*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "mlir/Support/LLVM.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/SmallVector.h" |
| #include <iterator> |
| |
| namespace mlir { |
| /// A 2D array where each row may have different length. Elements of each row |
| /// are stored contiguously, but rows don't have a fixed order in the storage. |
| template <typename T> |
| class RaggedArray { |
| public: |
| /// Returns the number of rows in the 2D array. |
| size_t size() const { return slices.size(); } |
| |
| /// Returns true if the are no rows in the 2D array. Note that an array with a |
| /// non-zero number of empty rows is *NOT* empty. |
| bool empty() const { return slices.empty(); } |
| |
| /// Accesses `pos`-th row. |
| ArrayRef<T> operator[](size_t pos) const { return at(pos); } |
| ArrayRef<T> at(size_t pos) const { |
| if (slices[pos].first == static_cast<size_t>(-1)) |
| return ArrayRef<T>(); |
| return ArrayRef<T>(storage).slice(slices[pos].first, slices[pos].second); |
| } |
| MutableArrayRef<T> operator[](size_t pos) { return at(pos); } |
| MutableArrayRef<T> at(size_t pos) { |
| if (slices[pos].first == static_cast<size_t>(-1)) |
| return MutableArrayRef<T>(); |
| return MutableArrayRef<T>(storage).slice(slices[pos].first, |
| slices[pos].second); |
| } |
| |
| /// Iterator over the rows. |
| class iterator |
| : public llvm::iterator_facade_base< |
| iterator, std::forward_iterator_tag, MutableArrayRef<T>, |
| std::ptrdiff_t, MutableArrayRef<T> *, MutableArrayRef<T>> { |
| public: |
| /// Creates the start iterator. |
| explicit iterator(RaggedArray &ragged) : ragged(ragged), pos(0) {} |
| |
| /// Creates the end iterator. |
| iterator(RaggedArray &ragged, size_t pos) : ragged(ragged), pos(pos) {} |
| |
| /// Dereferences the current iterator. Assumes in-bounds. |
| MutableArrayRef<T> operator*() const { return ragged[pos]; } |
| |
| /// Increments the iterator. |
| iterator &operator++() { |
| if (pos < ragged.slices.size()) |
| ++pos; |
| return *this; |
| } |
| |
| /// Compares the two iterators. Iterators into different ragged arrays |
| /// compare not equal. |
| bool operator==(const iterator &other) const { |
| return &ragged == &other.ragged && pos == other.pos; |
| } |
| |
| private: |
| RaggedArray &ragged; |
| size_t pos; |
| }; |
| |
| /// Constant iterator over the rows. |
| class const_iterator |
| : public llvm::iterator_facade_base< |
| const_iterator, std::forward_iterator_tag, ArrayRef<T>, |
| std::ptrdiff_t, ArrayRef<T> *, ArrayRef<T>> { |
| public: |
| /// Creates the start iterator. |
| explicit const_iterator(const RaggedArray &ragged) |
| : ragged(ragged), pos(0) {} |
| |
| /// Creates the end iterator. |
| const_iterator(const RaggedArray &ragged, size_t pos) |
| : ragged(ragged), pos(pos) {} |
| |
| /// Dereferences the current iterator. Assumes in-bounds. |
| ArrayRef<T> operator*() const { return ragged[pos]; } |
| |
| /// Increments the iterator. |
| const_iterator &operator++() { |
| if (pos < ragged.slices.size()) |
| ++pos; |
| return *this; |
| } |
| |
| /// Compares the two iterators. Iterators into different ragged arrays |
| /// compare not equal. |
| bool operator==(const const_iterator &other) const { |
| return &ragged == &other.ragged && pos == other.pos; |
| } |
| |
| private: |
| const RaggedArray &ragged; |
| size_t pos; |
| }; |
| |
| /// Iterator over rows. |
| const_iterator begin() const { return const_iterator(*this); } |
| const_iterator end() const { return const_iterator(*this, slices.size()); } |
| iterator begin() { return iterator(*this); } |
| iterator end() { return iterator(*this, slices.size()); } |
| |
| /// Reserve space to store `size` rows with `nestedSize` elements each. |
| void reserve(size_t size, size_t nestedSize = 0) { |
| slices.reserve(size); |
| storage.reserve(size * nestedSize); |
| } |
| |
| /// Appends the given range of elements as a new row to the 2D array. May |
| /// invalidate the end iterator. |
| template <typename Range> |
| void push_back(Range &&elements) { |
| slices.push_back(appendToStorage(std::forward<Range>(elements))); |
| } |
| |
| /// Replaces the `pos`-th row in the 2D array with the given range of |
| /// elements. Invalidates iterators and references to `pos`-th and all |
| /// succeeding rows. |
| template <typename Range> |
| void replace(size_t pos, Range &&elements) { |
| if (slices[pos].first != static_cast<size_t>(-1)) { |
| auto from = std::next(storage.begin(), slices[pos].first); |
| auto to = std::next(from, slices[pos].second); |
| auto newFrom = storage.erase(from, to); |
| // Update the array refs after the underlying storage was shifted. |
| for (size_t i = pos + 1, e = size(); i < e; ++i) { |
| slices[i] = std::make_pair(std::distance(storage.begin(), newFrom), |
| slices[i].second); |
| std::advance(newFrom, slices[i].second); |
| } |
| } |
| slices[pos] = appendToStorage(std::forward<Range>(elements)); |
| } |
| |
| /// Appends `num` empty rows to the array. |
| void appendEmptyRows(size_t num) { |
| slices.resize(slices.size() + num, std::pair<size_t, size_t>(-1, 0)); |
| } |
| |
| /// Removes the first subarray in-place. Invalidates iterators to all rows. |
| void removeFront() { slices.erase(slices.begin()); } |
| |
| private: |
| /// Appends the given elements to the storage and returns an ArrayRef |
| /// pointing to them in the storage. |
| template <typename Range> |
| std::pair<size_t, size_t> appendToStorage(Range &&elements) { |
| size_t start = storage.size(); |
| llvm::append_range(storage, std::forward<Range>(elements)); |
| return std::make_pair(start, storage.size() - start); |
| } |
| |
| /// Outer elements of the ragged array. Each entry is an (offset, length) |
| /// pair identifying a contiguous segment in the `storage` list that |
| /// contains the actual elements. This allows for elements to be stored |
| /// contiguously without nested vectors and for different segments to be set |
| /// or replaced in any order. |
| SmallVector<std::pair<size_t, size_t>> slices; |
| |
| /// Dense storage for ragged array elements. |
| SmallVector<T> storage; |
| }; |
| } // namespace mlir |