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Diffstat (limited to 'source/blender/blenlib/BLI_array_ref.h')
| -rw-r--r-- | source/blender/blenlib/BLI_array_ref.h | 426 |
1 files changed, 426 insertions, 0 deletions
diff --git a/source/blender/blenlib/BLI_array_ref.h b/source/blender/blenlib/BLI_array_ref.h new file mode 100644 index 00000000000..e34647676d8 --- /dev/null +++ b/source/blender/blenlib/BLI_array_ref.h @@ -0,0 +1,426 @@ +/* + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version 2 + * of the License, or (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software Foundation, + * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + */ + +#ifndef __BLI_ARRAY_REF_H__ +#define __BLI_ARRAY_REF_H__ + +/** \file + * \ingroup bli + * + * These classes offer a convenient way to work with continuous chunks of memory of a certain type. + * We differentiate #ArrayRef and #MutableArrayRef. The elements in the former are const while the + * elements in the other are not. + * + * Passing array references as parameters has multiple benefits: + * - Less templates are used because the function does not have to work with different + * container types. + * - It encourages an Struct-of-Arrays data layout which is often beneficial when + * writing high performance code. Also it makes it easier to reuse code. + * - Array references offer convenient ways of slicing and other operations. + * + * The instances of #ArrayRef and #MutableArrayRef are very small and should be passed by value. + * Since array references do not own any memory, it is generally not save to store them. + */ + +#include <vector> +#include <array> +#include <algorithm> +#include <iostream> +#include <string> + +#include "BLI_utildefines.h" +#include "BLI_memory_utils_cxx.h" +#include "BLI_index_range.h" + +namespace BLI { + +/** + * References an array of data. The elements in the array should not be changed. + */ +template<typename T> class ArrayRef { + private: + const T *m_start = nullptr; + uint m_size = 0; + + public: + /** + * Create a reference to an empty array. + * The pointer is allowed to be nullptr. + */ + ArrayRef() = default; + + ArrayRef(const T *start, uint size) : m_start(start), m_size(size) + { + } + + ArrayRef(const std::initializer_list<T> &list) : ArrayRef(list.begin(), list.size()) + { + } + + ArrayRef(const std::vector<T> &vector) : ArrayRef(vector.data(), vector.size()) + { + } + + template<std::size_t N> ArrayRef(const std::array<T, N> &array) : ArrayRef(array.data(), N) + { + } + + /** + * Return a continuous part of the array. + * Asserts that the slice stays within the array. + */ + ArrayRef slice(uint start, uint size) const + { + BLI_assert(start + size <= this->size() || size == 0); + return ArrayRef(m_start + start, size); + } + + ArrayRef slice(IndexRange range) const + { + return this->slice(range.start(), range.size()); + } + + /** + * Return a new ArrayRef with n elements removed from the beginning. + * Asserts that the array contains enough elements. + */ + ArrayRef drop_front(uint n = 1) const + { + BLI_assert(n <= this->size()); + return this->slice(n, this->size() - n); + } + + /** + * Return a new ArrayRef with n elements removed from the beginning. + * Asserts that the array contains enough elements. + */ + ArrayRef drop_back(uint n = 1) const + { + BLI_assert(n <= this->size()); + return this->slice(0, this->size() - n); + } + + /** + * Return a new ArrayRef that only contains the first n elements. + * Asserts that the array contains enough elements. + */ + ArrayRef take_front(uint n) const + { + BLI_assert(n <= this->size()); + return this->slice(0, n); + } + + /** + * Return a new ArrayRef that only contains the last n elements. + * Asserts that the array contains enough elements. + */ + ArrayRef take_back(uint n) const + { + BLI_assert(n <= this->size()); + return this->slice(this->size() - n, n); + } + + /** + * Copy the values in this array to another array. + */ + void copy_to(T *ptr) const + { + BLI::copy_n(m_start, m_size, ptr); + } + + const T *begin() const + { + return m_start; + } + + const T *end() const + { + return m_start + m_size; + } + + /** + * Access an element in the array. + * Asserts that the index is in the bounds of the array. + */ + const T &operator[](uint index) const + { + BLI_assert(index < m_size); + return m_start[index]; + } + + /** + * Return the number of elements in the referenced array. + */ + uint size() const + { + return m_size; + } + + /** + * Return the number of bytes referenced by this ArrayRef. + */ + uint byte_size() const + { + return sizeof(T) * m_size; + } + + /** + * Does a linear search to see of the value is in the array. + * Return true if it is, otherwise false. + */ + bool contains(const T &value) const + { + for (const T &element : *this) { + if (element == value) { + return true; + } + } + return false; + } + + /** + * Does a constant time check to see if the pointer is within the referenced array. + * Return true if it is, otherwise false. + */ + bool contains_ptr(const T *ptr) const + { + return (this->begin() <= ptr) && (ptr < this->end()); + } + + /** + * Does a linear search to count how often the value is in the array. + * Returns the number of occurrences. + */ + uint count(const T &value) const + { + uint counter = 0; + for (const T &element : *this) { + if (element == value) { + counter++; + } + } + return counter; + } + + /** + * Return a reference to the first element in the array. + * Asserts that the array is not empty. + */ + const T &first() const + { + BLI_assert(m_size > 0); + return m_start[0]; + } + + /** + * Return a reference to the last element in the array. + * Asserts that the array is not empty. + */ + const T &last() const + { + BLI_assert(m_size > 0); + return m_start[m_size - 1]; + } + + /** + * Get element at the given index. If the index is out of range, return the fallback value. + */ + T get(uint index, const T &fallback) const + { + if (index < m_size) { + return m_start[index]; + } + return fallback; + } + + /** + * Get a new array ref to the same underlying memory buffer. No conversions are done. + * Asserts when the sizes of the types don't match. + */ + template<typename NewT> ArrayRef<NewT> cast() const + { + /* Can be adjusted to allow different type sizes when necessary. */ + BLI_STATIC_ASSERT(sizeof(T) == sizeof(NewT), ""); + return ArrayRef<NewT>((NewT *)m_start, m_size); + } + + /** + * A debug utility to print the content of the array ref. Every element will be printed on a + * separate line using the given callback. + */ + template<typename PrintLineF> void print_as_lines(std::string name, PrintLineF print_line) const + { + std::cout << "ArrayRef: " << name << " \tSize:" << m_size << '\n'; + for (const T &value : *this) { + std::cout << " "; + print_line(value); + std::cout << '\n'; + } + } +}; + +/** + * Mostly the same as ArrayRef, except that one can change the array elements via this reference. + */ +template<typename T> class MutableArrayRef { + private: + T *m_start; + uint m_size; + + public: + MutableArrayRef() = default; + + MutableArrayRef(T *start, uint size) : m_start(start), m_size(size) + { + } + + MutableArrayRef(std::initializer_list<T> &list) : MutableArrayRef(list.begin(), list.size()) + { + } + + MutableArrayRef(std::vector<T> &vector) : MutableArrayRef(vector.data(), vector.size()) + { + } + + template<std::size_t N> + MutableArrayRef(std::array<T, N> &array) : MutableArrayRef(array.data(), N) + { + } + + operator ArrayRef<T>() + { + return ArrayRef<T>(m_start, m_size); + } + + /** + * Get the number of elements in the array. + */ + uint size() const + { + return m_size; + } + + /** + * Replace all elements in the referenced array with the given value. + */ + void fill(const T &element) + { + std::fill_n(m_start, m_size, element); + } + + /** + * Replace a subset of all elements with the given value. + */ + void fill_indices(ArrayRef<uint> indices, const T &element) + { + for (uint i : indices) { + m_start[i] = element; + } + } + + /** + * Copy the values from another array into the references array. + */ + void copy_from(const T *ptr) + { + BLI::copy_n(ptr, m_size, m_start); + } + + void copy_from(ArrayRef<T> other) + { + BLI_assert(this->size() == other.size()); + this->copy_from(other.begin()); + } + + T *begin() const + { + return m_start; + } + + T *end() const + { + return m_start + m_size; + } + + T &operator[](uint index) const + { + BLI_assert(index < this->size()); + return m_start[index]; + } + + /** + * Return a continuous part of the array. + * Asserts that the slice stays in the array bounds. + */ + MutableArrayRef slice(uint start, uint length) const + { + BLI_assert(start + length <= this->size()); + return MutableArrayRef(m_start + start, length); + } + + /** + * Return a new MutableArrayRef with n elements removed from the beginning. + */ + MutableArrayRef drop_front(uint n = 1) const + { + BLI_assert(n <= this->size()); + return this->slice(n, this->size() - n); + } + + /** + * Return a new MutableArrayRef with n elements removed from the beginning. + */ + MutableArrayRef drop_back(uint n = 1) const + { + BLI_assert(n <= this->size()); + return this->slice(0, this->size() - n); + } + + /** + * Return a new MutableArrayRef that only contains the first n elements. + */ + MutableArrayRef take_front(uint n) const + { + BLI_assert(n <= this->size()); + return this->slice(0, n); + } + + /** + * Return a new MutableArrayRef that only contains the last n elements. + */ + MutableArrayRef take_back(uint n) const + { + BLI_assert(n <= this->size()); + return this->slice(this->size() - n, n); + } + + ArrayRef<T> as_ref() const + { + return ArrayRef<T>(m_start, m_size); + } +}; + +/** + * Shorthand to make use of automatic template parameter deduction. + */ +template<typename T> ArrayRef<T> ref_c_array(const T *array, uint size) +{ + return ArrayRef<T>(array, size); +} + +} /* namespace BLI */ + +#endif /* __BLI_ARRAY_REF_H__ */ |