10 files changed, 232 insertions, 82 deletions

diff --git a/includes/image_io/base/istream_data_source.h b/includes/image_io/base/istream_data_source.h
index 4564e14..9b87542 100644
--- a/includes/image_io/base/istream_data_source.h
+++ b/includes/image_io/base/istream_data_source.h
@@ -1,46 +1,28 @@
 #ifndef IMAGE_IO_BASE_ISTREAM_DATA_SOURCE_H_  // NOLINT
 #define IMAGE_IO_BASE_ISTREAM_DATA_SOURCE_H_  // NOLINT
 
-#include <iostream>
 #include <memory>
 #include <utility>
 
-#include "image_io/base/data_source.h"
+#include "image_io/base/istream_ref_data_source.h"
 
 namespace photos_editing_formats {
 namespace image_io {
 
-/// A DataSource that obtains data from an istream.
-class IStreamDataSource : public DataSource {
+/// A DataSource that obtains data from an istream that it owns.
+class IStreamDataSource : public IStreamRefDataSource {
  public:
   /// Constructs an IStreamDataSource using the given istream.
   /// @param istram_ptr The istream from which to read.
   explicit IStreamDataSource(std::unique_ptr<std::istream> istream_ptr)
-      : istream_(std::move(istream_ptr)) {}
-
-  void Reset() override;
-  std::shared_ptr<DataSegment> GetDataSegment(size_t begin,
-                                              size_t min_size) override;
-  TransferDataResult TransferData(const DataRange& data_range, size_t best_size,
-                                  DataDestination* data_destination) override;
-
- private:
-  /// The worker function to create a DataSegment and fill it with the given
-  /// number of bytes read from the istream, starting at the given location.
-  /// @param begin The location in the istream at which to start reading.
-  /// @param count The number of bytes to read.
-  /// @return A DataSegment pointer, or nullptr if the read failed.
-  std::shared_ptr<DataSegment> Read(size_t begin, size_t count);
+      : IStreamRefDataSource(*istream_ptr), istream_(std::move(istream_ptr)) {}
 
  private:
-  /// The istream from which to read.
+  /// The istream that is owned by this data source.
   std::unique_ptr<std::istream> istream_;
-
-  /// The current data segment that was read in the GetDataSegment() function.
-  std::shared_ptr<DataSegment> current_data_segment_;
 };
 
 }  // namespace image_io
 }  // namespace photos_editing_formats
 
-#endif // IMAGE_IO_BASE_ISTREAM_DATA_SOURCE_H_  // NOLINT
+#endif  // IMAGE_IO_BASE_ISTREAM_DATA_SOURCE_H_  // NOLINT
diff --git a/includes/image_io/base/istream_ref_data_source.h b/includes/image_io/base/istream_ref_data_source.h
new file mode 100644
index 0000000..2460bb1
--- /dev/null
+++ b/includes/image_io/base/istream_ref_data_source.h
@@ -0,0 +1,46 @@
+#ifndef IMAGE_IO_BASE_ISTREAM_REF_DATA_SOURCE_H_  // NOLINT
+#define IMAGE_IO_BASE_ISTREAM_REF_DATA_SOURCE_H_  // NOLINT
+
+#include <iostream>
+
+#include "image_io/base/data_source.h"
+
+namespace photos_editing_formats {
+namespace image_io {
+
+/// A DataSource that obtains data from an istream held as a reference.
+class IStreamRefDataSource : public DataSource {
+ public:
+  /// Constructs an IStreamDataSource using the given istream.
+  /// @param istream_ref The istream from which to read.
+  explicit IStreamRefDataSource(std::istream& istream_ref)
+      : istream_ref_(istream_ref) {}
+  IStreamRefDataSource(const IStreamRefDataSource&) = delete;
+  IStreamRefDataSource& operator=(const IStreamRefDataSource&) = delete;
+
+  void Reset() override;
+  std::shared_ptr<DataSegment> GetDataSegment(size_t begin,
+                                              size_t min_size) override;
+  TransferDataResult TransferData(const DataRange& data_range, size_t best_size,
+                                  DataDestination* data_destination) override;
+
+ private:
+  /// The worker function to create a DataSegment and fill it with the given
+  /// number of bytes read from the istream, starting at the given location.
+  /// @param begin The location in the istream at which to start reading.
+  /// @param count The number of bytes to read.
+  /// @return A DataSegment pointer, or nullptr if the read failed.
+  std::shared_ptr<DataSegment> Read(size_t begin, size_t count);
+
+ private:
+  /// The istream from which to read.
+  std::istream& istream_ref_;
+
+  /// The current data segment that was read in the GetDataSegment() function.
+  std::shared_ptr<DataSegment> current_data_segment_;
+};
+
+}  // namespace image_io
+}  // namespace photos_editing_formats
+
+#endif  // IMAGE_IO_BASE_ISTREAM_REF_DATA_SOURCE_H_  // NOLINT
diff --git a/includes/image_io/base/message.h b/includes/image_io/base/message.h
index 8c225d8..fef2fd6 100644
--- a/includes/image_io/base/message.h
+++ b/includes/image_io/base/message.h
@@ -15,6 +15,9 @@ class Message {
     /// A Status message.
     kStatus,
 
+    /// A Warning message.
+    kWarning,
+
     /// An error from the stdlib was detected. The std::errno variable can be
     /// used to programmatically decide what to do, or use the std::strerror
     /// function to get a string description of the error.
@@ -66,6 +69,17 @@ class Message {
   /// @return The text of the message.
   const std::string& GetText() const { return text_; }
 
+  /// @return Whether the message is an error message.
+  bool IsError() const {
+    return type_ != Message::kStatus && type_ != Message::kWarning;
+  }
+
+  /// @return Whether the message is a warning message.
+  bool IsWarning() const { return type_ == Message::kWarning; }
+
+  /// @return Whether the message is a status message.
+  bool IsStatus() const { return type_ == Message::kStatus; }
+
  private:
   /// The type of message.
   Type type_;
diff --git a/includes/image_io/base/message_handler.h b/includes/image_io/base/message_handler.h
index dc33679..b60a593 100644
--- a/includes/image_io/base/message_handler.h
+++ b/includes/image_io/base/message_handler.h
@@ -5,6 +5,7 @@
 #include <vector>
 
 #include "image_io/base/message.h"
+#include "image_io/base/message_stats.h"
 #include "image_io/base/message_store.h"
 #include "image_io/base/message_writer.h"
 
@@ -15,20 +16,9 @@ namespace image_io {
 /// to report status and error conditions.
 class MessageHandler {
  public:
-  /// Initializes the MessageHandler for client use. Multithread applications
-  /// might find this function useful to call in their initialization section,
-  /// to guarentee that threads will not create race conditions when calling the
-  /// Get function for the first time.
-  static void Init(std::unique_ptr<MessageWriter> message_writer,
-                   std::unique_ptr<MessageStore> message_store);
-
-  /// This function is thread-safe as long as the Init() function is called in
-  /// non-multiple-threaded startup code; if the Init() fucnction was not called
-  /// there may be race conditions that causes the message handler returned from
-  /// Get() called in one thread to be different from that returned by the call
-  /// in a different thread.
-  /// @return The message handler used by the code in this library.
-  static MessageHandler* Get();
+  /// The default constructor for MessageHandler creates a MessageWriter and
+  /// VectorMessageStore for handling writing and storing messages.
+  MessageHandler();
 
   /// Sets the message writer to use when ReportMessage() is called. If client
   /// code does not call this function, the MessageHandler returned by the Get()
@@ -55,14 +45,29 @@ class MessageHandler {
   /// should call this function again so that memory is not leaked when it is
   /// done using this library.
   void ClearMessages() {
+    message_stats_->Clear();
     if (message_store_) {
       message_store_->ClearMessages();
     }
   }
 
   /// @return Whether the message handler's store has error messages or not.
-  bool HasErrorMessages() const {
-    return message_store_ ? message_store_->HasErrorMessages() : false;
+  bool HasErrorMessages() const { return GetErrorMessageCount() > 0; }
+
+  /// @return The number of error messages reported.
+  size_t GetErrorMessageCount() const { return message_stats_->error_count; }
+
+  /// @return The number of warning messages reported.
+  size_t GetWarningMessageCount() const {
+    return message_stats_->warning_count;
+  }
+
+  /// @return The number of status messages reported.
+  size_t GetStatusMessageCount() const { return message_stats_->status_count; }
+
+  /// @return The message stats object as a shared pointer.
+  std::shared_ptr<MessageStats> GetMessageStats() const {
+    return message_stats_;
   }
 
   /// @return The vector of errors maintained by the message handler's store.
@@ -85,15 +90,14 @@ class MessageHandler {
   void ReportMessage(const Message& message);
 
  private:
-  MessageHandler() = default;
-  ~MessageHandler();
-
- private:
   /// The message writer used by ReportMessage, or null.
   std::unique_ptr<MessageWriter> message_writer_;
 
   /// The message store for saving messages for later, or null.
   std::unique_ptr<MessageStore> message_store_;
+
+  /// The message stats for counting messages.
+  std::shared_ptr<MessageStats> message_stats_;
 };
 
 }  // namespace image_io
diff --git a/includes/image_io/base/message_stats.h b/includes/image_io/base/message_stats.h
new file mode 100644
index 0000000..6b338f0
--- /dev/null
+++ b/includes/image_io/base/message_stats.h
@@ -0,0 +1,21 @@
+#ifndef IMAGE_IO_BASE_MESSAGE_STATS_H_  // NOLINT
+#define IMAGE_IO_BASE_MESSAGE_STATS_H_  // NOLINT
+
+#include "image_io/base/types.h"
+
+namespace photos_editing_formats {
+namespace image_io {
+
+/// A structure for holding message stats.
+struct MessageStats {
+  MessageStats() { Clear(); }
+  void Clear() { error_count = warning_count = status_count = 0; }
+  size_t error_count;
+  size_t warning_count;
+  size_t status_count;
+};
+
+}  // namespace image_io
+}  // namespace photos_editing_formats
+
+#endif  // IMAGE_IO_BASE_MESSAGE_STATS_H_  // NOLINT
diff --git a/includes/image_io/base/message_store.h b/includes/image_io/base/message_store.h
index 1d492f1..8db0b9f 100644
--- a/includes/image_io/base/message_store.h
+++ b/includes/image_io/base/message_store.h
@@ -61,7 +61,7 @@ class ErrorFlagMessageStore : public MessageStore {
   ErrorFlagMessageStore() : has_error_(false) {}
   void ClearMessages() override { has_error_ = false; }
   void AddMessage(const Message& message) override {
-    if (message.GetType() != Message::kStatus) {
+    if (message.IsError()) {
       has_error_ = true;
     }
   }
diff --git a/includes/image_io/base/ostream_data_destination.h b/includes/image_io/base/ostream_data_destination.h
index 15a1155..d0cf04c 100644
--- a/includes/image_io/base/ostream_data_destination.h
+++ b/includes/image_io/base/ostream_data_destination.h
@@ -1,58 +1,31 @@
 #ifndef IMAGE_IO_BASE_OSTREAM_DATA_DESTINATION_H_  // NOLINT
 #define IMAGE_IO_BASE_OSTREAM_DATA_DESTINATION_H_  // NOLINT
 
-#include <iostream>
 #include <memory>
-#include <string>
 #include <utility>
 
-#include "image_io/base/data_destination.h"
+#include "image_io/base/ostream_ref_data_destination.h"
 
 namespace photos_editing_formats {
 namespace image_io {
 
 /// A DataDestination that writes its output to an ostream.
-class OStreamDataDestination : public DataDestination {
+class OStreamDataDestination : public OStreamRefDataDestination {
  public:
   /// Constructs an OStreamDataDestination using the given ostream.
   /// @param ostream_ptr The ostream to which data is written.
-  explicit OStreamDataDestination(std::unique_ptr<std::ostream> ostream_ptr)
-      : ostream_(std::move(ostream_ptr)),
-        bytes_transferred_(0),
-        has_error_(false) {}
-
-  /// @param name A name to associate with the ostream. Used for error messages.
-  void SetName(const std::string& name) { name_ = name; }
-
-  /// @return The name associated with the ostream.
-  const std::string& GetName() const { return name_; }
-
-  /// @return The number of bytes written to the ostream.
-  size_t GetBytesTransferred() const override { return bytes_transferred_; }
-
-  /// @return True if errors were encountered while writing to the ostream.
-  bool HasError() const { return has_error_; }
-
-  void StartTransfer() override;
-  TransferStatus Transfer(const DataRange& transfer_range,
-                          const DataSegment& data_segment) override;
-  void FinishTransfer() override;
+  /// @param message_handler An option message handler for writing messages.
+  OStreamDataDestination(std::unique_ptr<std::ostream> ostream_ptr,
+                         MessageHandler* message_handler)
+      : OStreamRefDataDestination(*ostream_ptr, message_handler),
+        ostream_(std::move(ostream_ptr)) {}
 
  private:
-  /// The ostream written to.
+  /// The ostream that is owned by this data destination.
   std::unique_ptr<std::ostream> ostream_;
-
-  /// The number of bytes written so far.
-  size_t bytes_transferred_;
-
-  /// A (file) name to associate with the ostream, used with error messages.
-  std::string name_;
-
-  /// If true indicates an error has occurred writing to the ostream.
-  bool has_error_;
 };
 
 }  // namespace image_io
 }  // namespace photos_editing_formats
 
-#endif // IMAGE_IO_BASE_OSTREAM_DATA_DESTINATION_H_  // NOLINT
+#endif  // IMAGE_IO_BASE_OSTREAM_DATA_DESTINATION_H_  // NOLINT
diff --git a/includes/image_io/base/ostream_ref_data_destination.h b/includes/image_io/base/ostream_ref_data_destination.h
new file mode 100644
index 0000000..266e2be
--- /dev/null
+++ b/includes/image_io/base/ostream_ref_data_destination.h
@@ -0,0 +1,66 @@
+#ifndef IMAGE_IO_BASE_OSTREAM_REF_DATA_DESTINATION_H_  // NOLINT
+#define IMAGE_IO_BASE_OSTREAM_REF_DATA_DESTINATION_H_  // NOLINT
+
+#include <iostream>
+#include <string>
+
+#include "image_io/base/data_destination.h"
+#include "image_io/base/message_handler.h"
+
+namespace photos_editing_formats {
+namespace image_io {
+
+/// A DataDestination that writes its output to an ostream held as a reference.
+class OStreamRefDataDestination : public DataDestination {
+ public:
+  /// Constructs an OStreamDataDestination using the given ostream.
+  /// @param ostream_ref The ostream to which data is written.
+  /// @param message_handler An option message handler for writing messages.
+  OStreamRefDataDestination(std::ostream& ostream_ref,
+                            MessageHandler* message_handler)
+      : ostream_ref_(ostream_ref),
+        message_handler_(message_handler),
+        bytes_transferred_(0),
+        has_error_(false) {}
+  OStreamRefDataDestination(const OStreamRefDataDestination&) = delete;
+  OStreamRefDataDestination& operator=(const OStreamRefDataDestination&) =
+      delete;
+
+  /// @param name A name to associate with the ostream. Used for error messages.
+  void SetName(const std::string& name) { name_ = name; }
+
+  /// @return The name associated with the ostream.
+  const std::string& GetName() const { return name_; }
+
+  /// @return The number of bytes written to the ostream.
+  size_t GetBytesTransferred() const override { return bytes_transferred_; }
+
+  /// @return True if errors were encountered while writing to the ostream.
+  bool HasError() const { return has_error_; }
+
+  void StartTransfer() override;
+  TransferStatus Transfer(const DataRange& transfer_range,
+                          const DataSegment& data_segment) override;
+  void FinishTransfer() override;
+
+ private:
+  /// The ostream written to.
+  std::ostream& ostream_ref_;
+
+  /// An optional message handler to write messages to.
+  MessageHandler* message_handler_;
+
+  /// The number of bytes written so far.
+  size_t bytes_transferred_;
+
+  /// A (file) name to associate with the ostream, used with error messages.
+  std::string name_;
+
+  /// If true indicates an error has occurred writing to the ostream.
+  bool has_error_;
+};
+
+}  // namespace image_io
+}  // namespace photos_editing_formats
+
+#endif  // IMAGE_IO_BASE_OSTREAM_REF_DATA_DESTINATION_H_  // NOLINT
diff --git a/includes/image_io/base/types.h b/includes/image_io/base/types.h
index aaa88b3..ed49350 100644
--- a/includes/image_io/base/types.h
+++ b/includes/image_io/base/types.h
@@ -7,8 +7,14 @@
 namespace photos_editing_formats {
 namespace image_io {
 
-/// Byte is the noumenon unit of data.
+/// The various integer and byte types used in this package.
 using Byte = std::uint8_t;
+using Int32 = std::int32_t;
+using Int64 = std::int64_t;
+using UInt8 = std::uint8_t;
+using UInt16 = std::uint16_t;
+using UInt32 = std::uint32_t;
+using UInt64 = std::uint64_t;
 
 /// A Byte value and a validity flag.
 struct ValidatedByte {
diff --git a/includes/image_io/base/validated_number.h b/includes/image_io/base/validated_number.h
new file mode 100644
index 0000000..ead5ab3
--- /dev/null
+++ b/includes/image_io/base/validated_number.h
@@ -0,0 +1,38 @@
+#ifndef IMAGE_IO_BASE_VALIDATED_NUMBER_H_  // NOLINT
+#define IMAGE_IO_BASE_VALIDATED_NUMBER_H_  // NOLINT
+
+#include <sstream>
+#include <string>
+
+namespace photos_editing_formats {
+namespace image_io {
+
+template <class T>
+struct ValidatedNumber {
+  ValidatedNumber() : ValidatedNumber(T(), false) {}
+  ValidatedNumber(const T& value_, bool is_valid_)
+      : value(value_), is_valid(is_valid_) {}
+  using value_type = T;
+  T value;
+  bool is_valid;
+};
+
+template <class T>
+ValidatedNumber<T> GetValidatedNumber(const std::string& str) {
+  std::stringstream ss(str);
+  ValidatedNumber<T> result;
+  ss >> result.value;
+  if (!ss.fail()) {
+    std::string extra;
+    ss >> extra;
+    if (extra.empty()) {
+      result.is_valid = true;
+    }
+  }
+  return result;
+}
+
+}  // namespace image_io
+}  // namespace photos_editing_formats
+
+#endif  // IMAGE_IO_BASE_VALIDATED_NUMBER_H_  // NOLINT