// Ceres Solver - A fast non-linear least squares minimizer
// Copyright 2015 Google Inc. All rights reserved.
// http://ceres-solver.org/
//
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// modification, are permitted provided that the following conditions are met:
//
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//   this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright notice,
//   this list of conditions and the following disclaimer in the documentation
//   and/or other materials provided with the distribution.
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//   used to endorse or promote products derived from this software without
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// Author: sameeragarwal@google.com (Sameer Agarwal)

#ifndef CERES_INTERNAL_BLOCK_RANDOM_ACCESS_DENSE_MATRIX_H_
#define CERES_INTERNAL_BLOCK_RANDOM_ACCESS_DENSE_MATRIX_H_

#include <memory>
#include <vector>

#include "ceres/block_random_access_matrix.h"
#include "ceres/internal/disable_warnings.h"
#include "ceres/internal/export.h"

namespace ceres::internal {

// A square block random accessible matrix with the same row and
// column block structure. All cells are stored in the same single
// array, so that its also accessible as a dense matrix of size
// num_rows x num_cols.
//
// This class is NOT thread safe. Since all n^2 cells are stored,
// GetCell never returns nullptr for any (row_block_id, col_block_id)
// pair.
//
// ReturnCell is a nop.
class CERES_NO_EXPORT BlockRandomAccessDenseMatrix
    : public BlockRandomAccessMatrix {
 public:
  // blocks is a vector of block sizes. The resulting matrix has
  // blocks.size() * blocks.size() cells.
  explicit BlockRandomAccessDenseMatrix(const std::vector<int>& blocks);
  BlockRandomAccessDenseMatrix(const BlockRandomAccessDenseMatrix&) = delete;
  void operator=(const BlockRandomAccessDenseMatrix&) = delete;

  // The destructor is not thread safe. It assumes that no one is
  // modifying any cells when the matrix is being destroyed.
  ~BlockRandomAccessDenseMatrix() override;

  // BlockRandomAccessMatrix interface.
  CellInfo* GetCell(int row_block_id,
                    int col_block_id,
                    int* row,
                    int* col,
                    int* row_stride,
                    int* col_stride) final;

  // This is not a thread safe method, it assumes that no cell is
  // locked.
  void SetZero() final;

  // Since the matrix is square with the same row and column block
  // structure, num_rows() = num_cols().
  int num_rows() const final { return num_rows_; }
  int num_cols() const final { return num_rows_; }

  // The underlying matrix storing the cells.
  const double* values() const { return values_.get(); }
  double* mutable_values() { return values_.get(); }

 private:
  int num_rows_;
  std::vector<int> block_layout_;
  std::unique_ptr<double[]> values_;
  std::unique_ptr<CellInfo[]> cell_infos_;
};

}  // namespace ceres::internal

#include "ceres/internal/reenable_warnings.h"

#endif  // CERES_INTERNAL_BLOCK_RANDOM_ACCESS_DENSE_MATRIX_H_