multitable.hpp

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// Copyright 2012 Yandex Artem Babenko
#pragma once

#include <vector>

using std::vector;

template<class T>
struct Multitable {
  Multitable(const vector<int>& dimensions = vector<int>());
  void Resize(const vector<int>& dimensions, T value = T());
  void SetValue(T value, const vector<int>& cell_indices);
  T GetValue(const vector<int>& cell_indices);
  vector<T> table;
  vector<int> dimensions;
  template<class Archive>
  void serialize(Archive& arc, unsigned int version) {
    arc & table;
    arc & dimensions;
  }
  int GetCellGlobalIndex(const vector<int>& cell_indices) const;
};

template<class T>
int Multitable<T>::GetCellGlobalIndex(const vector<int>& indices) const {
  if(indices.empty()) {
    throw std::logic_error("Empty indices array!");
  }
  int global_index = 0;
  int subtable_capacity = table.size();
  for(int dimension_index = 0; dimension_index < dimensions.size(); ++dimension_index) {
    subtable_capacity = subtable_capacity / dimensions[dimension_index];
    global_index += subtable_capacity * indices[dimension_index];
  }
  return global_index;
}

template<class T>
void Multitable<T>::Resize(const vector<int>& new_dimensions, T value) {
  int table_size = 1;
  dimensions = new_dimensions;
  for(int dimension_index = 0; dimension_index < new_dimensions.size(); ++dimension_index) {
    table_size *= new_dimensions[dimension_index];
  }
  table.resize(table_size, value);
}

template<class T>
Multitable<T>::Multitable(const vector<int>& dimensions) {
  Resize(dimensions);
}

template<class T>
void Multitable<T>::SetValue(T value, const vector<int>& indices) {
  int global_index = GetCellGlobalIndex(indices);
  table.at(global_index) = value;
}

template<class T>
T Multitable<T>::GetValue(const vector<int>& indices) {
  int global_index = GetCellGlobalIndex(indices);
  return table.at(global_index);
}