text: /*===================== begin_copyright_notice ==================================
  
  Copyright (c) 2017 Intel Corporation
  
  Permission is hereby granted, free of charge, to any person obtaining a
  copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:
  
  The above copyright notice and this permission notice shall be included
  in all copies or substantial portions of the Software.
  
  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
  OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
  CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
  TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
  SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  
  
  ======================= end_copyright_notice ==================================*/
  
  #ifndef _METADATA_H_
  #define _METADATA_H_
  
  #include <optional>
  #include <iostream>
  
  namespace vISA
  {
  
  //
  // A metadata is simply a collection of (<key>, <value>) pairs that may be attached to an IR object (BB, Inst, Declare, etc.)
  // Metadata is completely optional; vISA optimizations and transformations are not obliged to preserve them, and dropping them should not affect correctness
  // Metadata key is a string, and only one value is allowed per key for now.
  // Metadata value is represented by an MDNode abstract class, each subclass provides the actual implementation of the metadata value
  // Currently there are only two types of metadata: MDString and MDLocation.
  // Metadata memory management is performed by IR_Builder through the various allocaeMD* methods.
  // An MDNode may be shared among muitiple IR objects, it's the user's responsiblity to ensure correct ownership and sharing behaviors.
  // Each object has its own unqiue metadata map, however.
  // Currently only G4_INST supports metadata through the setMetaData/getMetadata interface.
  // OPEN: use enum instead of string as metadata key. This would speed up lookup at the expense of some flexibility.
  // OPEN: better management schemes for a MDNode's lifetime/ownership.
  //
  
  enum class MDType
  {
      String,
      SrcLoc
  };
  
  // forward declaration so that the asMD*() calls can work
  class MDString;
  class MDLocation;
  
  class MDNode
  {
  
      const MDType nodeType;
  
  protected:
      MDNode(MDType ty) : nodeType(ty) {}
  
   public:
  
      MDNode(const MDNode& node) = delete;
  
      void operator=(const MDNode& node) = delete;
  
      void* operator new(size_t sz, Mem_Manager& m) { return m.alloc(sz); }
  
      virtual ~MDNode() {}
  
      bool isMDString() const { return nodeType == MDType::String; }
      bool isMDLocation() const { return nodeType == MDType::SrcLoc; }
  
      const MDString* asMDString() const
      {
          return isMDString() ? reinterpret_cast<const MDString*>(this) : nullptr;
      }
  
      MDLocation* asMDLocation() const
      {
          return isMDLocation() ? reinterpret_cast<MDLocation*>(const_cast<MDNode*>(this)) : nullptr;
      }
  
      virtual void print(std::ostream& OS) const = 0;
      void dump() const
      {
          print(std::cerr);
      }
  };
  
  class MDString : public MDNode
  {
      const std::string data;
  
  public:
  
      MDString(const std::string& str) : MDNode(MDType::String), data(str) {}
  
      MDString(const MDString& node) = delete;
  
      void operator=(const MDString& node) = delete;
  
      virtual ~MDString() = default;
  
      std::string getData() const { return data; }
  
      void print(std::ostream& OS) const
      {
          OS << "\"" << data << "\"";
      }
  };
  
  class MDLocation : public MDNode
  {
      int lineNo = -1;
      const char* srcFilename = nullptr;
  
  public:
  
      MDLocation(int lineNo, const char* srcFilename) :
          MDNode(MDType::SrcLoc), lineNo(lineNo), srcFilename(srcFilename) {}
  
      MDLocation(const MDLocation& node) = delete;
  
      void operator=(const MDLocation& node) = delete;
  
      ~MDLocation() = default;
  
      void* operator new(size_t sz, Mem_Manager& m) { return m.alloc(sz); }
      int getLineNo() const { return lineNo; }
      const char* getSrcFilename() const { return srcFilename; }
  
      void print(std::ostream& OS) const
      {
          OS << "\"" << srcFilename << ":" << lineNo << "\"";
      }
  };
  
  
  class Metadata
  {
  
      std::unordered_map<std::string, MDNode*> MDMap;
  
  public:
      explicit Metadata() {}
  
      Metadata(const Metadata& md) = delete;
  
      virtual ~Metadata() {}
  
      void* operator new(size_t sz, Mem_Manager& m) { return m.alloc(sz); }
  
      // it simply overwrites existing value for key if it already exists
      void setMetadata(const std::string& key, MDNode* value)
      {
          if (!value)
          {
              // do not allow nullptr value for now. ToDo: distinguish between nullptr value vs. metadata not set?
              return;
          }
          MDMap.emplace(key, value);
      }
  
      MDNode* getMetadata(const std::string& key)
      {
          auto iter = MDMap.find(key);
          return iter != MDMap.end() ? iter->second : nullptr;
      }
  
      bool isMetadataSet(const std::string& key)
      {
          return MDMap.count(key);
      }
  
      void print(std::ostream& OS) const
      {
          for (auto&& iter : MDMap)
          {
              OS << "\"" << iter.first << "\" : ";
              iter.second->print(OS);
              OS << "\n";
          }
      }
  
      void dump() const
      {
          print(std::cerr);
      }
  
      // list the known keys here to avoid typos
      inline static const std::string InstComment = "comment";
      inline static const std::string InstLoc = "location";
  };
  
  }
  
  #endif
  