src/utils/tmpfile.h

// Copyright 2021 The Tint Authors.
//
// Licensed 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, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef SRC_UTILS_TMPFILE_H_
#define SRC_UTILS_TMPFILE_H_

#include <sstream>
#include <string>

namespace tint {
namespace utils {

/// TmpFile constructs a temporary file that can be written to, and is
/// automatically deleted on destruction.
class TmpFile {
 public:
  /// Constructor.
  /// Creates a new temporary file which can be written to.
  /// The temporary file will be automatically deleted on destruction.
  /// @param extension optional file extension to use with the file. The file
  /// have no extension by default.
  explicit TmpFile(std::string extension = "");

  /// Destructor.
  /// Deletes the temporary file.
  ~TmpFile();

  /// @return true if the temporary file was successfully created.
  operator bool() { return !path_.empty(); }

  /// @return the path to the temporary file
  std::string Path() const { return path_; }

  /// Opens the temporary file and appends |size| bytes from |data| to the end
  /// of the temporary file. The temporary file is closed again before
  /// returning, allowing other processes to open the file on operating systems
  /// that require exclusive ownership of opened files.
  /// @param data the data to write to the end of the file
  /// @param size the number of bytes to write from data
  /// @returns true on success, otherwise false
  bool Append(const void* data, size_t size) const;

  /// Appends the argument to the end of the file.
  /// @param data the data to write to the end of the file
  /// @return a reference to this TmpFile
  template <typename T>
  inline TmpFile& operator<<(T&& data) {
    std::stringstream ss;
    ss << data;
    std::string str = ss.str();
    Append(str.data(), str.size());
    return *this;
  }

 private:
  TmpFile(const TmpFile&) = delete;
  TmpFile& operator=(const TmpFile&) = delete;

  std::string path_;
};

}  // namespace utils
}  // namespace tint

#endif  //  SRC_UTILS_TMPFILE_H_