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
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
//
// TextEncoding.h
//
// Library: Foundation
// Package: Text
// Module: TextEncoding
//
// Definition of the abstract TextEncoding class.
//
// Copyright (c) 2004-2007, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier: BSL-1.0
//
#ifndef Foundation_TextEncoding_INCLUDED
#define Foundation_TextEncoding_INCLUDED
#include "Poco/Foundation.h"
#include "Poco/SharedPtr.h"
namespace Poco {
class TextEncodingManager;
class Foundation_API TextEncoding
/// An abstract base class for implementing text encodings
/// like UTF-8 or ISO 8859-1.
///
/// Subclasses must override the canonicalName(), isA(),
/// characterMap() and convert() methods and need to be
/// thread safe and stateless.
///
/// TextEncoding also provides static member functions
/// for managing mappings from encoding names to
/// TextEncoding objects.
{
public:
typedef SharedPtr<TextEncoding> Ptr;
enum
{
MAX_SEQUENCE_LENGTH = 4 /// The maximum character byte sequence length supported.
};
typedef int CharacterMap[256];
/// The map[b] member gives information about byte sequences
/// whose first byte is b.
/// If map[b] is c where c is >= 0, then b by itself encodes the Unicode scalar value c.
/// If map[b] is -1, then the byte sequence is malformed.
/// If map[b] is -n, where n >= 2, then b is the first byte of an n-byte
/// sequence that encodes a single Unicode scalar value. Byte sequences up
/// to 4 bytes in length are supported.
virtual ~TextEncoding();
/// Destroys the encoding.
virtual const char* canonicalName() const = 0;
/// Returns the canonical name of this encoding,
/// e.g. "ISO-8859-1". Encoding name comparisons are case
/// insensitive.
virtual bool isA(const std::string& encodingName) const = 0;
/// Returns true if the given name is one of the names of this encoding.
/// For example, the "ISO-8859-1" encoding is also known as "Latin-1".
///
/// Encoding name comparisions are case insensitive.
virtual const CharacterMap& characterMap() const = 0;
/// Returns the CharacterMap for the encoding.
/// The CharacterMap should be kept in a static member. As
/// characterMap() can be called frequently, it should be
/// implemented in such a way that it just returns a static
/// map. If the map is built at runtime, this should be
/// done in the constructor.
virtual int convert(const unsigned char* bytes) const;
/// The convert function is used to convert multibyte sequences;
/// bytes will point to a byte sequence of n bytes where
/// sequenceLength(bytes, length) == -n, with length >= n.
///
/// The convert function must return the Unicode scalar value
/// represented by this byte sequence or -1 if the byte sequence is malformed.
///
/// The default implementation returns (int) bytes[0].
virtual int queryConvert(const unsigned char* bytes, int length) const;
/// The queryConvert function is used to convert single byte characters
/// or multibyte sequences;
/// bytes will point to a byte sequence of length bytes.
///
/// The queryConvert function must return the Unicode scalar value
/// represented by this byte sequence or -1 if the byte sequence is malformed
/// or -n where n is number of bytes requested for the sequence, if length is
/// shorter than the sequence.
/// The length of the sequence might not be determined by the first byte,
/// in which case the conversion becomes an iterative process:
/// First call with length == 1 might return -2,
/// Then a second call with length == 2 might return -4
/// Eventually, the third call with length == 4 should return either a
/// Unicode scalar value, or -1 if the byte sequence is malformed.
///
/// The default implementation returns (int) bytes[0].
virtual int sequenceLength(const unsigned char* bytes, int length) const;
/// The sequenceLength function is used to get the lenth of the sequence pointed
/// by bytes. The length parameter should be greater or equal to the length of
/// the sequence.
///
/// The sequenceLength function must return the length of the sequence
/// represented by this byte sequence or a negative value -n if length is
/// shorter than the sequence, where n is the number of byte requested
/// to determine the length of the sequence.
/// The length of the sequence might not be determined by the first byte,
/// in which case the conversion becomes an iterative process as long as the
/// result is negative:
/// First call with length == 1 might return -2,
/// Then a second call with length == 2 might return -4
/// Eventually, the third call with length == 4 should return 4.
/// The default implementation returns 1.
virtual int convert(int ch, unsigned char* bytes, int length) const;
/// Transform the Unicode character ch into the encoding's
/// byte sequence. The method returns the number of bytes
/// used. The method must not use more than length characters.
/// Bytes and length can also be null - in this case only the number
/// of bytes required to represent ch is returned.
/// If the character cannot be converted, 0 is returned and
/// the byte sequence remains unchanged.
/// The default implementation simply returns 0.
static TextEncoding& byName(const std::string& encodingName);
/// Returns the TextEncoding object for the given encoding name.
///
/// Throws a NotFoundException if the encoding with given name is not available.
static TextEncoding::Ptr find(const std::string& encodingName);
/// Returns a pointer to the TextEncoding object for the given encodingName,
/// or NULL if no such TextEncoding object exists.
static void add(TextEncoding::Ptr encoding);
/// Adds the given TextEncoding to the table of text encodings,
/// under the encoding's canonical name.
///
/// If an encoding with the given name is already registered,
/// it is replaced.
static void add(TextEncoding::Ptr encoding, const std::string& name);
/// Adds the given TextEncoding to the table of text encodings,
/// under the given name.
///
/// If an encoding with the given name is already registered,
/// it is replaced.
static void remove(const std::string& encodingName);
/// Removes the encoding with the given name from the table
/// of text encodings.
static TextEncoding::Ptr global(TextEncoding::Ptr encoding);
/// Sets global TextEncoding object.
///
/// This function sets the global encoding to the argument and returns a
/// reference of the previous global encoding.
static TextEncoding& global();
/// Return the current global TextEncoding object
static const std::string GLOBAL;
/// Name of the global TextEncoding, which is the empty string.
protected:
static TextEncodingManager& manager();
/// Returns the TextEncodingManager.
};
} // namespace Poco
#endif // Foundation_TextEncoding_INCLUDED
|
