name_supply.h

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 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
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 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
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 */
 
#ifndef TVM_IR_NAME_SUPPLY_H_
#define TVM_IR_NAME_SUPPLY_H_
 
#include <algorithm>
#include <string>
#include <unordered_map>
#include <utility>
 
#include "tvm/ir/expr.h"
 
namespace tvm {
 
class NameSupplyNode : public Object {
 public:
  NameSupplyNode() = default;
 
  NameSupplyNode(const String& prefix, std::unordered_map<std::string, int> name_map)
      : prefix_(prefix), name_map(std::move(name_map)) {}
 
  String FreshName(const String& name, bool add_prefix = true, bool add_underscore = true);
 
  String ReserveName(const String& name, bool add_prefix = true);
 
  bool ContainsName(const String& name, bool add_prefix = true);
 
  void VisitAttrs(AttrVisitor* v) {}
 
  // Prefix for all GlobalVar names. It can be empty.
  std::string prefix_;
 
  static constexpr const char* _type_key = "NameSupply";
  static constexpr const bool _type_has_method_sequal_reduce = false;
  static constexpr const bool _type_has_method_shash_reduce = false;
  TVM_DECLARE_FINAL_OBJECT_INFO(NameSupplyNode, Object);
 
 private:
  String add_prefix_to_name(const String& name);
 
  std::string GetUniqueName(std::string name, bool add_underscore = true);
 
  std::unordered_map<std::string, int> name_map;
};
 
class NameSupply : public ObjectRef {
 public:
  TVM_DLL explicit NameSupply(const String& prefix = "",
                              std::unordered_map<std::string, int> name_map = {});
 
  template <typename Iter, typename Lambda>
  TVM_DLL explicit NameSupply(Iter begin, Iter end, Lambda f)
      : NameSupply("", GetNameMap(begin, end, f)) {}
 
  TVM_DEFINE_MUTABLE_NOTNULLABLE_OBJECT_REF_METHODS(NameSupply, ObjectRef, NameSupplyNode);
 
 private:
  template <typename Iter, typename Lambda>
  static std::unordered_map<std::string, int> GetNameMap(Iter begin, Iter end, Lambda f) {
    // static_assert is more reader-friendly than SFINAE when template specialization is not needed.
    static_assert(std::is_convertible<decltype(f(*begin)), std::string>::value,
                  "Lambda f must has a signature of [?](*it) -> string {}");
    std::unordered_map<std::string, int> name_map;
    for (auto it = begin; it != end; ++it) {
      const std::string& name = f(*it);
      const size_t idx_last_first_num = std::distance(
          std::find_if(name.rbegin(), name.rend(), [](char c) { return !std::isdigit(c); }),
          name.rend());
      // name = {O = others}{D = consecutive digits}
      // let O -> prefix;
      std::string prefix = name.substr(0, idx_last_first_num);
      ICHECK(prefix.size() > 0 && std::isalpha(prefix[0])) << "Invalid variable name: " << name;
      if (0 == name_map.count(prefix)) name_map[prefix] = 0;
      if (idx_last_first_num < name.size()) {  // has some digits.
                                               // let D's nearest natural number -> idx;
                                               // note: stoul("000123") = 123;
        name_map[prefix] = std::max(name_map[prefix], std::stoi(name.substr(idx_last_first_num)));
      }
    }
    return name_map;
  }
};
 
}  // namespace tvm
 
#endif  // TVM_IR_NAME_SUPPLY_H_