native_library.h

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// Copyright 2013 The Flutter 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 FLUTTER_FML_NATIVE_LIBRARY_H_
#define FLUTTER_FML_NATIVE_LIBRARY_H_
 
#include <optional>
 
#include "flutter/fml/build_config.h"
#include "flutter/fml/macros.h"
#include "flutter/fml/memory/ref_counted.h"
#include "flutter/fml/memory/ref_ptr.h"
 
#if defined(FML_OS_WIN)
#include "flutter/fml/platform/win/windows_shim.h"
#endif  // defined(FML_OS_WIN)
 
namespace fml {
class NativeLibrary : public fml::RefCountedThreadSafe<NativeLibrary> {
 public:
#if FML_OS_WIN
  using Handle = HMODULE;
  using SymbolHandle = FARPROC;
#else   // FML_OS_WIN
  using Handle = void*;
  using SymbolHandle = void*;
#endif  // FML_OS_WIN
 
  static fml::RefPtr<NativeLibrary> Create(const char* path);
 
  static fml::RefPtr<NativeLibrary> CreateWithHandle(
      Handle handle,
      bool close_handle_when_done);
 
  static fml::RefPtr<NativeLibrary> CreateForCurrentProcess();
 
  template <typename T>
  const std::optional<T> ResolveFunction(const char* symbol) {
    auto* resolved_symbol = Resolve(symbol);
    if (!resolved_symbol) {
      return std::nullopt;
    }
    return std::optional<T>(reinterpret_cast<T>(resolved_symbol));
  }
 
  const uint8_t* ResolveSymbol(const char* symbol) {
    auto* resolved_symbol = reinterpret_cast<const uint8_t*>(Resolve(symbol));
    if (resolved_symbol == nullptr) {
      FML_DLOG(INFO) << "Could not resolve symbol in library: " << symbol;
    }
    return resolved_symbol;
  }
 
 private:
  Handle handle_ = nullptr;
  bool close_handle_ = true;
 
  explicit NativeLibrary(const char* path);
 
  NativeLibrary(Handle handle, bool close_handle);
 
  ~NativeLibrary();
 
  Handle GetHandle() const;
  SymbolHandle Resolve(const char* symbol) const;
 
  FML_DISALLOW_COPY_AND_ASSIGN(NativeLibrary);
  FML_FRIEND_REF_COUNTED_THREAD_SAFE(NativeLibrary);
  FML_FRIEND_MAKE_REF_COUNTED(NativeLibrary);
};
 
}  // namespace fml
 
#endif  // FLUTTER_FML_NATIVE_LIBRARY_H_