text: // Copyright 2016 the V8 project authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef V8_WASM_SIGNATURE_MAP_H_
  #define V8_WASM_SIGNATURE_MAP_H_
  
  #include <map>
  
  #include "src/signature.h"
  #include "src/wasm/wasm-opcodes.h"
  
  namespace v8 {
  namespace internal {
  namespace wasm {
  
  // A signature map canonicalizes signatures into a range of indices so that
  // two different {FunctionSig} instances with the same contents map to the
  // same index.
  class V8_EXPORT_PRIVATE SignatureMap {
   public:
    // Allow default construction and move construction (because we have vectors
    // of objects containing SignatureMaps), but disallow copy or assign. It's
    // too easy to get security bugs by accidentally updating a copy of the map.
    MOVE_ONLY_WITH_DEFAULT_CONSTRUCTORS(SignatureMap);
  
    // Gets the index for a signature, assigning a new index if necessary.
    uint32_t FindOrInsert(FunctionSig* sig);
  
    // Gets the index for a signature, returning {-1} if not found.
    int32_t Find(FunctionSig* sig) const;
  
    // Disallows further insertions to this signature map.
    void Freeze() { frozen_ = true; }
  
   private:
    // TODO(wasm): use a hashmap instead of an ordered map?
    struct CompareFunctionSigs {
      bool operator()(FunctionSig* a, FunctionSig* b) const;
    };
    uint32_t next_ = 0;
    bool frozen_ = false;
    std::map<FunctionSig*, uint32_t, CompareFunctionSigs> map_;
  };
  
  }  // namespace wasm
  }  // namespace internal
  }  // namespace v8
  
  #endif  // V8_WASM_SIGNATURE_MAP_H_
  