Add static constructor for FileOutputStream returning pointer to base OutputStream

Author: xuepanchen

cpp/src/arrow/io/file.cc

@@ -554,6 +554,17 @@ FileOutputStream::~FileOutputStream() {
   DCHECK(impl_->Close().ok());
 }
 
+Status FileOutputStream::Open(const std::string& path,
+                              std::shared_ptr<OutputStream>* file) {
+  return Open(path, false, file);
+}
+
+Status FileOutputStream::Open(const std::string& path, bool append,
+                              std::shared_ptr<OutputStream>* out) {
+  *out = std::shared_ptr<FileOutputStream>(new FileOutputStream());
+  return std::static_pointer_cast<FileOutputStream>(*out)->impl_->Open(path, append);
+}
+
 Status FileOutputStream::Open(const std::string& path,
                               std::shared_ptr<FileOutputStream>* file) {
   return Open(path, false, file);

cpp/src/arrow/io/file.h

@@ -39,6 +39,21 @@ class ARROW_EXPORT FileOutputStream : public OutputStream {
  public:
   ~FileOutputStream() override;
 
+  /// \brief Open a local file for writing, truncating any existing file
+  /// \param[in] path with UTF8 encoding
+  /// \param[out] out a base interface OutputStream instance
+  ///
+  /// When opening a new file, any existing file with the indicated path is
+  /// truncated to 0 bytes, deleting any existing memory
+  static Status Open(const std::string& path, std::shared_ptr<OutputStream>* out);
+
+  /// \brief Open a local file for writing
+  /// \param[in] path with UTF8 encoding
+  /// \param[in] append append to existing file, otherwise truncate to 0 bytes
+  /// \param[out] out a base interface OutputStream instance
+  static Status Open(const std::string& path, bool append,
+                     std::shared_ptr<OutputStream>* out);
+
   /// \brief Open a local file for writing, truncating any existing file
   /// \param[in] path with UTF8 encoding
   /// \param[out] file a FileOutputStream instance