BLI_offset_span.hh

Go to the documentation of this file.

/* SPDX-FileCopyrightText: 2023 Blender Authors
 *
 * SPDX-License-Identifier: GPL-2.0-or-later */
 
#pragma once
 
#include "BLI_random_access_iterator_mixin.hh"
#include "BLI_span.hh"
 
namespace blender {
 
template<typename T, typename BaseT> class OffsetSpan {
 private:
  T offset_ = 0;
  Span<BaseT> data_;
 
 public:
  OffsetSpan() = default;
  OffsetSpan(const T offset, const Span<BaseT> data) : offset_(offset), data_(data) {}
 
  Span<BaseT> base_span() const
  {
    return data_;
  }
 
  T offset() const
  {
    return offset_;
  }
 
  bool is_empty() const
  {
    return data_.is_empty();
  }
 
  int64_t size() const
  {
    return data_.size();
  }
 
  T last(const int64_t n = 0) const
  {
    return offset_ + data_.last(n);
  }
 
  IndexRange index_range() const
  {
    return data_.index_range();
  }
 
  T operator[](const int64_t i) const
  {
    return T(data_[i]) + offset_;
  }
 
  OffsetSpan slice(const IndexRange &range) const
  {
    return {offset_, data_.slice(range)};
  }
 
  OffsetSpan slice(const int64_t start, const int64_t size) const
  {
    return {offset_, data_.slice(start, size)};
  }
 
  class Iterator : public iterator::RandomAccessIteratorMixin<Iterator> {
   public:
    using value_type = T;
    using pointer = const T *;
    using reference = T;
 
   private:
    T offset_;
    const BaseT *data_;
 
   public:
    Iterator(const T offset, const BaseT *data) : offset_(offset), data_(data) {}
 
    T operator*() const
    {
      return T(*data_) + offset_;
    }
 
    const BaseT *const &iter_prop() const
    {
      return data_;
    }
  };
 
  Iterator begin() const
  {
    return {offset_, data_.begin()};
  }
 
  Iterator end() const
  {
    return {offset_, data_.end()};
  }
};
 
}  // namespace blender