1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
|
#ifndef IMAGE_IO_BASE_MESSAGE_HANDLER_H_ // NOLINT
#define IMAGE_IO_BASE_MESSAGE_HANDLER_H_ // NOLINT
#include <memory>
#include <vector>
#include "image_io/base/message.h"
#include "image_io/base/message_store.h"
#include "image_io/base/message_writer.h"
namespace photos_editing_formats {
namespace image_io {
/// MessageHandler provides the functions that all the code in this library uses
/// 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();
/// Sets the message writer to use when ReportMessage() is called. If client
/// code does not call this function, the MessageHandler returned by the Get()
/// function will have a CoutMessageWriter by default. If client code calls
/// this function with a null, then ReportMessage() will not write messages at
/// all, but just add them to the messages store.
/// @param message_writer The message writer that ReportMessage uses, or null.
void SetMessageWriter(std::unique_ptr<MessageWriter> message_writer);
/// Sets the message store to use when ReportMessage() is called. If client
/// code does not call this function, the MessageHandler returned by the Get()
/// function will have a VectorMessageStore by default. If client code calls
/// this function with a null, then ReportMessage() will not save messages at
/// all, but just write them to the messages writer.
/// @param message_store The message store that ReportMessage uses, or null.
void SetMessageStore(std::unique_ptr<MessageStore> message_store);
/// Clears the messages maintained by the message handler's store. Client code
/// should call this function before calling any other standalone or class
/// function in this library so as to provide a clean starting point with
/// respect to error and status messages. Once all the calls have been made,
/// client code should examine the messages or call HasErrorMessages() to
/// determine the whether the calls succeeded or not. Finally client code
/// should call this function again so that memory is not leaked when it is
/// done using this library.
void ClearMessages() {
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;
}
/// @return The vector of errors maintained by the message handler's store.
std::vector<Message> GetMessages() const {
return message_store_ ? message_store_->GetMessages()
: std::vector<Message>();
}
/// Reports an error or a status message. This function is called from library
/// code when it detects an error condition or wants to report status. If the
/// message type is Message::kStdLibError, then the current value of the
/// system's errno variable is used when the message is created. The message
/// is added to the messages vector and if the message writer is not null, its
/// WriteMessage function is called.
/// @param type The type of message.
/// @param text Text associated with the message.
void ReportMessage(Message::Type type, const std::string& text);
/// @param message The message to report.
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_;
};
} // namespace image_io
} // namespace photos_editing_formats
#endif // IMAGE_IO_BASE_MESSAGE_HANDLER_H_ // NOLINT
|
