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#ifndef MULTITREE_IMPL_HPP
#define MULTITREE_IMPL_HPP
#include "multitree.hpp"
#include <memory>
namespace terraces {
namespace multitree_impl {
template <typename T>
struct array_deleter {
void operator()(T* ptr) { delete[] ptr; }
};
template <typename T>
std::unique_ptr<T[], array_deleter<T>> make_unique_array(std::size_t size) {
// this may leak memory if allocation or construction of a T fails
return std::unique_ptr<T[], array_deleter<T>>{new T[size]};
}
template <typename T>
class storage_block {
private:
std::unique_ptr<T[], array_deleter<T>> begin;
index_t size;
index_t max_size;
public:
storage_block(index_t max_size)
: begin{make_unique_array<T>(max_size)}, size{0}, max_size{max_size} {}
bool has_space(index_t required = 1) { return size + required <= max_size; }
T* get() {
assert(has_space());
return begin.get() + (size++);
}
T* get_range(index_t required) {
assert(has_space(required));
auto result = begin.get() + size;
size += required;
return result;
}
};
template <typename T>
class storage_blocks {
private:
std::vector<storage_block<T>> m_blocks;
index_t m_block_size;
index_t m_total_size;
index_t m_memory_limit;
public:
storage_blocks(index_t block_size = 1024)
: m_blocks{}, m_block_size{block_size}, m_total_size{block_size},
m_memory_limit{std::numeric_limits<index_t>::max()} {
m_blocks.emplace_back(m_block_size);
}
storage_blocks(const storage_blocks<T>& other) : storage_blocks{other.m_block_size} {}
storage_blocks(storage_blocks<T>&& other) = default;
storage_blocks<T>& operator=(const storage_blocks<T>& other) {
m_block_size = other.m_block_size;
return *this;
}
storage_blocks<T>& operator=(storage_blocks<T>&& other) = default;
index_t total_size() const { return sizeof(T) * m_total_size; }
T* get() {
if (!m_blocks.back().has_space()) {
m_blocks.emplace_back(m_block_size);
m_total_size += m_block_size;
}
return m_blocks.back().get();
}
T* get_range(index_t required) {
if (!m_blocks.back().has_space(required)) {
if (sizeof(T) * (m_total_size + required) > m_memory_limit) {
// fail allocation if we require too much memory
throw std::bad_alloc{};
}
m_blocks.emplace_back(required);
m_total_size += required;
auto result = m_blocks.back().get_range(required);
auto last_it = --m_blocks.end();
auto prev_it = --(--m_blocks.end());
std::iter_swap(
last_it,
prev_it); // TODO this might lead to some bad worst-case behaviour
return result;
}
return m_blocks.back().get_range(required);
}
void set_memory_limit(index_t memory_limit) { m_memory_limit = memory_limit; }
};
inline multitree_node* make_single_leaf(multitree_node* n, index_t i) {
n->type = multitree_node_type::base_single_leaf;
n->single_leaf = i;
n->num_leaves = 1;
n->num_trees = 1;
return n;
}
inline multitree_node* make_two_leaves(multitree_node* n, index_t i, index_t j) {
n->type = multitree_node_type::base_two_leaves;
n->two_leaves = {i, j};
n->num_leaves = 2;
n->num_trees = 1;
return n;
}
inline multitree_node* make_unconstrained(multitree_node* n, std::pair<index_t*, index_t*> range) {
auto begin = range.first;
auto end = range.second;
n->type = multitree_node_type::base_unconstrained;
n->unconstrained = {begin, end};
n->num_leaves = (index_t)(end - begin);
n->num_trees = count_unrooted_trees<index_t>(n->num_leaves);
return n;
}
inline multitree_node* make_inner_node(multitree_node* n, multitree_node* left,
multitree_node* right) {
n->type = multitree_node_type::inner_node;
n->inner_node = {left, right};
n->num_leaves = left->num_leaves + right->num_leaves;
n->num_trees = left->num_trees * right->num_trees;
return n;
}
inline multitree_node* make_alternative_array(multitree_node* n, multitree_node* begin,
index_t leaves) {
n->type = multitree_node_type::alternative_array;
n->alternative_array = {begin, begin};
n->num_leaves = leaves;
n->num_trees = 0;
return n;
}
inline multitree_node* make_unexplored(multitree_node* n, std::pair<index_t*, index_t*> range) {
auto begin = range.first;
auto end = range.second;
n->type = multitree_node_type::unexplored;
n->unexplored = {begin, end};
n->num_leaves = (index_t)(end - begin);
n->num_trees = 0;
return n;
}
} // namespace multitree_impl
} // namespace terraces
#endif // MULTITREE_IMPL_HPP
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