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MessageBuilder.h
1 /* mbed Microcontroller Library
2  * Copyright (c) 2018 ARM Limited
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  * http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #ifndef NFC_NDEF_MESSAGEBUILDER_H_
18 #define NFC_NDEF_MESSAGEBUILDER_H_
19 
20 #include <stdint.h>
21 
22 #include "platform/Span.h"
23 
24 #include "nfc/ndef/Record.h"
25 
26 namespace mbed {
27 namespace nfc {
28 namespace ndef {
29 
30 /** @addtogroup nfc
31  * @{
32  */
33 
34 /**
35  * Construct a NDEF Message.
36  */
38 
39 public:
40  /**
41  * Build a record payload.
42  */
43  struct PayloadBuilder {
44  /**
45  * Return the size of the payload built by this object.
46  *
47  * @return The size of the payload.
48  */
49  virtual size_t size() const = 0;
50 
51  /**
52  * Build the payload in a buffer that has the required size.
53  *
54  * @param buffer The buffer used to construct the payload.
55  */
56  virtual void build(const Span<uint8_t> &buffer) const = 0;
57 
58  protected:
59  /**
60  * Non virtual destructor.
61  */
63  };
64 
65  /**
66  * Create a new MessageBuilder that can be used to construct valid NDEF
67  * messages.
68  *
69  * @param buffer The data buffer that will contain the NDEF message.
70  */
71  MessageBuilder(const Span<uint8_t> &buffer);
72 
73  /**
74  * Append a new record to the message being built.
75  *
76  * @param type The type of the record to insert.
77  * @param payload The payload of the record (optional).
78  * @param is_last_record true if the record to insert is the last record of
79  * the payload or false otherwise.
80  *
81  * @return true if the record has been successfully inserted or false
82  * otherwise.
83  *
84  * @note insertion can fail if the message is already complete or if the
85  * size remaining in the message buffer is not large enough to makes the
86  * record inserted fit.
87  */
88  bool append_record(
89  const RecordType &type,
90  const RecordPayload &payload = RecordPayload(),
91  bool is_last_record = false
92  );
93 
94  /**
95  * Append a new record to the message being built.
96  *
97  * @param type The type of the record to insert.
98  * @param builder The builder of the payload.
99  * @param is_last_record true if the record to insert is the last record of
100  * the payload or false otherwise.
101  *
102  * @return true if the record has been successfully inserted or false
103  * otherwise.
104  *
105  * @note insertion can fail if the message is already complete or if the
106  * size remaining in the message buffer is not large enough to makes the
107  * record inserted fit.
108  */
109  bool append_record(
110  const RecordType &type,
111  const PayloadBuilder &builder,
112  bool is_last_record = false
113  );
114 
115  /**
116  * Append a new record to the message being built.
117  *
118  * @param record The record to insert.
119  * @param builder The builder that will construct the payload.
120  *
121  * @return true if the record has been successfully inserted or false otherwise.
122  *
123  * @note insertion can fail if the message is already complete or if the
124  * size remaining in the message buffer is not large enough to makes the
125  * record inserted fit.
126  */
127  bool append_record(
128  const Record &record,
129  const PayloadBuilder *builder = NULL
130  );
131 
132  /**
133  * Compute the size of a record.
134  *
135  * @param record The record used to compute the size.
136  * @param builder The payload builder if any.
137  *
138  * @return The size of the payload for the record in input.
139  */
140  static size_t compute_record_size(
141  const Record &record,
142  const PayloadBuilder *builder = NULL
143  );
144 
145  /**
146  * Reset the builder state.
147  */
148  void reset();
149 
150  /**
151  * Reset the builder state and assign a new buffer to it.
152  */
153  void reset(const Span<uint8_t> &buffer);
154 
155  /**
156  * Return true if the message stored is complete and false otherwise.
157  *
158  * @return true if the message is complete or false.
159  */
160  bool is_message_complete() const;
161 
162  /**
163  * Return the buffer storing the data if the message is complete or an empty
164  * buffer if the message is not complete.
165  *
166  * @return The message built.
167  */
169 
170 private:
171  // append fields
172  void append_header(const Record &record, const PayloadBuilder *);
173  void append_type_length(const Record &record);
174  void append_payload_length(const Record &, const PayloadBuilder *);
175  void append_id_length(const Record &);
176  void append_type(const Record &);
177  void append_id(const Record &);
178  void append_payload(const Record &, const PayloadBuilder *);
179 
180  // helpers
181  static bool is_short_payload(const Record &record, const PayloadBuilder *);
182  static size_t get_payload_size(const Record &, const PayloadBuilder *);
183 
184  // builder state.
185  Span<uint8_t> _message_buffer;
186  size_t _position;
187  bool _message_started;
188  bool _message_ended;
189  bool _in_chunk;
190 };
191 /** @}*/
192 } // namespace ndef
193 } // namespace nfc
194 } // namespace mbed
195 
196 #endif /* NFC_NDEF_MESSAGEBUILDER_H_ */
Construct a NDEF Message.
MessageBuilder(const Span< uint8_t > &buffer)
Create a new MessageBuilder that can be used to construct valid NDEF messages.
bool append_record(const RecordType &type, const RecordPayload &payload=RecordPayload(), bool is_last_record=false)
Append a new record to the message being built.
virtual void build(const Span< uint8_t > &buffer) const =0
Build the payload in a buffer that has the required size.
void reset()
Reset the builder state.
static size_t compute_record_size(const Record &record, const PayloadBuilder *builder=NULL)
Compute the size of a record.
Span< const uint8_t > get_message() const
Return the buffer storing the data if the message is complete or an empty buffer if the message is no...
Represent a record.
Definition: Record.h:148
virtual size_t size() const =0
Return the size of the payload built by this object.
Span< const uint8_t > RecordPayload
Definition of a Record payload.
Definition: Record.h:136
Encode a record type.
Definition: Record.h:52
Definition: AnalogIn.h:28
bool is_message_complete() const
Return true if the message stored is complete and false otherwise.
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