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1 // Copyright (C) 2010, International Business Machines | |
2 // Corporation and others. All Rights Reserved. | |
3 // | |
4 // Copyright 2001 and onwards Google Inc. | |
5 // Author: Sanjay Ghemawat | |
6 | |
7 // This code is a contribution of Google code, and the style used here is | |
8 // a compromise between the original Google code and the ICU coding guidelines. | |
9 // For example, data types are ICU-ified (size_t,int->int32_t), | |
10 // and API comments doxygen-ified, but function names and behavior are | |
11 // as in the original, if possible. | |
12 // Assertion-style error handling, not available in ICU, was changed to | |
13 // parameter "pinning" similar to UnicodeString. | |
14 // | |
15 // In addition, this is only a partial port of the original Google code, | |
16 // limited to what was needed so far. The (nearly) complete original code | |
17 // is in the ICU svn repository at icuhtml/trunk/design/strings/contrib | |
18 // (see ICU ticket 6765, r25517). | |
19 | |
20 #ifndef __STRINGPIECE_H__ | |
21 #define __STRINGPIECE_H__ | |
22 | |
23 /** | |
24 * \file | |
25 * \brief C++ API: StringPiece: Read-only byte string wrapper class. | |
26 */ | |
27 | |
28 #include "unicode/utypes.h" | |
29 #include "unicode/uobject.h" | |
30 #include "unicode/std_string.h" | |
31 | |
32 // Arghh! I wish C++ literals were "string". | |
33 | |
34 U_NAMESPACE_BEGIN | |
35 | |
36 /** | |
37 * A string-like object that points to a sized piece of memory. | |
38 * | |
39 * We provide non-explicit singleton constructors so users can pass | |
40 * in a "const char*" or a "string" wherever a "StringPiece" is | |
41 * expected. | |
42 * | |
43 * Functions or methods may use const StringPiece& parameters to accept either | |
44 * a "const char*" or a "string" value that will be implicitly converted to | |
45 * a StringPiece. | |
46 * | |
47 * Systematic usage of StringPiece is encouraged as it will reduce unnecessary | |
48 * conversions from "const char*" to "string" and back again. | |
49 * | |
50 * @stable ICU 4.2 | |
51 */ | |
52 class U_COMMON_API StringPiece : public UMemory { | |
53 private: | |
54 const char* ptr_; | |
55 int32_t length_; | |
56 | |
57 public: | |
58 /** | |
59 * Default constructor, creates an empty StringPiece. | |
60 * @stable ICU 4.2 | |
61 */ | |
62 StringPiece() : ptr_(NULL), length_(0) { } | |
63 /** | |
64 * Constructs from a NUL-terminated const char * pointer. | |
65 * @param str a NUL-terminated const char * pointer | |
66 * @stable ICU 4.2 | |
67 */ | |
68 StringPiece(const char* str); | |
69 #if U_HAVE_STD_STRING | |
70 /** | |
71 * Constructs from a std::string. | |
72 * @stable ICU 4.2 | |
73 */ | |
74 StringPiece(const U_STD_NSQ string& str) | |
75 : ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { } | |
76 #endif | |
77 /** | |
78 * Constructs from a const char * pointer and a specified length. | |
79 * @param offset a const char * pointer (need not be terminated) | |
80 * @param len the length of the string; must be non-negative | |
81 * @stable ICU 4.2 | |
82 */ | |
83 StringPiece(const char* offset, int32_t len) : ptr_(offset), length_(len) { } | |
84 /** | |
85 * Substring of another StringPiece. | |
86 * @param x the other StringPiece | |
87 * @param pos start position in x; must be non-negative and <= x.length(). | |
88 * @stable ICU 4.2 | |
89 */ | |
90 StringPiece(const StringPiece& x, int32_t pos); | |
91 /** | |
92 * Substring of another StringPiece. | |
93 * @param x the other StringPiece | |
94 * @param pos start position in x; must be non-negative and <= x.length(). | |
95 * @param len length of the substring; | |
96 * must be non-negative and will be pinned to at most x.length() -
pos. | |
97 * @stable ICU 4.2 | |
98 */ | |
99 StringPiece(const StringPiece& x, int32_t pos, int32_t len); | |
100 | |
101 /** | |
102 * Returns the string pointer. May be NULL if it is empty. | |
103 * | |
104 * data() may return a pointer to a buffer with embedded NULs, and the | |
105 * returned buffer may or may not be null terminated. Therefore it is | |
106 * typically a mistake to pass data() to a routine that expects a NUL | |
107 * terminated string. | |
108 * @return the string pointer | |
109 * @stable ICU 4.2 | |
110 */ | |
111 const char* data() const { return ptr_; } | |
112 /** | |
113 * Returns the string length. Same as length(). | |
114 * @return the string length | |
115 * @stable ICU 4.2 | |
116 */ | |
117 int32_t size() const { return length_; } | |
118 /** | |
119 * Returns the string length. Same as size(). | |
120 * @return the string length | |
121 * @stable ICU 4.2 | |
122 */ | |
123 int32_t length() const { return length_; } | |
124 /** | |
125 * Returns whether the string is empty. | |
126 * @return TRUE if the string is empty | |
127 * @stable ICU 4.2 | |
128 */ | |
129 UBool empty() const { return length_ == 0; } | |
130 | |
131 /** | |
132 * Sets to an empty string. | |
133 * @stable ICU 4.2 | |
134 */ | |
135 void clear() { ptr_ = NULL; length_ = 0; } | |
136 | |
137 /** | |
138 * Reset the stringpiece to refer to new data. | |
139 * @param data pointer the new string data. Need not be nul terminated. | |
140 * @param len the length of the new data | |
141 * @internal | |
142 */ | |
143 void set(const char* data, int32_t len) { ptr_ = data; length_ = len; } | |
144 | |
145 /** | |
146 * Reset the stringpiece to refer to new data. | |
147 * @param str a pointer to a NUL-terminated string. | |
148 * @internal | |
149 */ | |
150 void set(const char* str); | |
151 | |
152 /** | |
153 * Removes the first n string units. | |
154 * @param n prefix length, must be non-negative and <=length() | |
155 * @stable ICU 4.2 | |
156 */ | |
157 void remove_prefix(int32_t n) { | |
158 if (n >= 0) { | |
159 if (n > length_) { | |
160 n = length_; | |
161 } | |
162 ptr_ += n; | |
163 length_ -= n; | |
164 } | |
165 } | |
166 | |
167 /** | |
168 * Removes the last n string units. | |
169 * @param n suffix length, must be non-negative and <=length() | |
170 * @stable ICU 4.2 | |
171 */ | |
172 void remove_suffix(int32_t n) { | |
173 if (n >= 0) { | |
174 if (n <= length_) { | |
175 length_ -= n; | |
176 } else { | |
177 length_ = 0; | |
178 } | |
179 } | |
180 } | |
181 | |
182 /** | |
183 * Maximum integer, used as a default value for substring methods. | |
184 * @stable ICU 4.2 | |
185 */ | |
186 static const int32_t npos = 0x7fffffff; | |
187 | |
188 /** | |
189 * Returns a substring of this StringPiece. | |
190 * @param pos start position; must be non-negative and <= length(). | |
191 * @param len length of the substring; | |
192 * must be non-negative and will be pinned to at most length() - po
s. | |
193 * @return the substring StringPiece | |
194 * @stable ICU 4.2 | |
195 */ | |
196 StringPiece substr(int32_t pos, int32_t len = npos) const { | |
197 return StringPiece(*this, pos, len); | |
198 } | |
199 }; | |
200 | |
201 /** | |
202 * Global operator == for StringPiece | |
203 * @param x The first StringPiece to compare. | |
204 * @param y The second StringPiece to compare. | |
205 * @return TRUE if the string data is equal | |
206 * @internal | |
207 */ | |
208 U_EXPORT UBool U_EXPORT2 | |
209 operator==(const StringPiece& x, const StringPiece& y); | |
210 | |
211 /** | |
212 * Global operator != for StringPiece | |
213 * @param x The first StringPiece to compare. | |
214 * @param y The second StringPiece to compare. | |
215 * @return TRUE if the string data is not equal | |
216 * @internal | |
217 */ | |
218 inline UBool operator!=(const StringPiece& x, const StringPiece& y) { | |
219 return !(x == y); | |
220 } | |
221 | |
222 U_NAMESPACE_END | |
223 | |
224 #endif // __STRINGPIECE_H__ | |
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