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/*
* 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 benefitial 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 occurences.
*/
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 elemeent 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.
* Aserts 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__ */
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