text: // Copyright (C) 2021 Intel Corporation
  // SPDX-License-Identifier: Apache-2.0
  //
  
  #include "transformations/op_conversions/convert_gather_0d.hpp"
  
  #include "itt.hpp"
  
  #include <memory>
  #include <vector>
  
  #include <ngraph/opsets/opset1.hpp>
  #include <ngraph/rt_info.hpp>
  #include <ngraph/pattern/op/wrap_type.hpp>
  
  NGRAPH_RTTI_DEFINITION(ngraph::pass::ConvertGather0D, "ConvertGather0D", 0);
  
  ngraph::pass::ConvertGather0D::ConvertGather0D() {
      MATCHER_SCOPE(ConvertGather0D);
      auto gather = ngraph::pattern::wrap_type<opset1::Gather>();
  
      ngraph::matcher_pass_callback callback = [](pattern::Matcher &m) {
          auto gather = std::dynamic_pointer_cast<ngraph::opset1::Gather>(m.get_match_root());
          if (!gather) {
              return false;
          }
  
          auto axes_constant = std::dynamic_pointer_cast<ngraph::opset1::Constant>(gather->input_value(2).get_node_shared_ptr());
          if (!axes_constant) {
              return false;
          }
  
          // if the input with indices is scalar we need to unsqueeze it to 1D so plugins which do not support 0D can
          // execute this layer. Then we need to squeeze the axis dimension to restore original shape of gather output
          auto indices = gather->input_value(1);
          const auto indices_rank = indices.get_partial_shape().rank();
          if (indices_rank.is_dynamic() || indices_rank.get_length() != 0) {
              return false;
          }
  
          auto axis = axes_constant->cast_vector<int64_t>()[0];
          indices = std::make_shared<ngraph::opset1::Unsqueeze>(indices, opset1::Constant::create(element::i64, Shape{1}, {0}));
          auto gather_new = std::make_shared<ngraph::opset1::Gather>(gather->input_value(0), indices, axes_constant);
          auto sq = std::make_shared<ngraph::opset1::Squeeze>(gather_new, opset1::Constant::create(element::i64, Shape{1}, {axis}));
          sq->set_friendly_name(gather->get_friendly_name());
  
          ngraph::copy_runtime_info(gather, {indices.get_node_shared_ptr(), gather_new, sq});
          ngraph::replace_node(gather, sq);
  
          return true;
      };
  
      auto m1 = std::make_shared<ngraph::pattern::Matcher>(gather, matcher_name);
      this->register_matcher(m1, callback);
  }
  