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1 : // © 2016 and later: Unicode, Inc. and others.
2 : // License & terms of use: http://www.unicode.org/copyright.html
3 : // Copyright (C) 2009-2013, International Business Machines
4 : // Corporation and others. All Rights Reserved.
5 : //
6 : // Copyright 2001 and onwards Google Inc.
7 : // Author: Sanjay Ghemawat
8 :
9 : // This code is a contribution of Google code, and the style used here is
10 : // a compromise between the original Google code and the ICU coding guidelines.
11 : // For example, data types are ICU-ified (size_t,int->int32_t),
12 : // and API comments doxygen-ified, but function names and behavior are
13 : // as in the original, if possible.
14 : // Assertion-style error handling, not available in ICU, was changed to
15 : // parameter "pinning" similar to UnicodeString.
16 : //
17 : // In addition, this is only a partial port of the original Google code,
18 : // limited to what was needed so far. The (nearly) complete original code
19 : // is in the ICU svn repository at icuhtml/trunk/design/strings/contrib
20 : // (see ICU ticket 6765, r25517).
21 :
22 : #ifndef __STRINGPIECE_H__
23 : #define __STRINGPIECE_H__
24 :
25 : /**
26 : * \file
27 : * \brief C++ API: StringPiece: Read-only byte string wrapper class.
28 : */
29 :
30 : #include "unicode/utypes.h"
31 : #include "unicode/uobject.h"
32 : #include "unicode/std_string.h"
33 :
34 : // Arghh! I wish C++ literals were "string".
35 :
36 : U_NAMESPACE_BEGIN
37 :
38 : /**
39 : * A string-like object that points to a sized piece of memory.
40 : *
41 : * We provide non-explicit singleton constructors so users can pass
42 : * in a "const char*" or a "string" wherever a "StringPiece" is
43 : * expected.
44 : *
45 : * Functions or methods may use StringPiece parameters to accept either a
46 : * "const char*" or a "string" value that will be implicitly converted to a
47 : * StringPiece.
48 : *
49 : * Systematic usage of StringPiece is encouraged as it will reduce unnecessary
50 : * conversions from "const char*" to "string" and back again.
51 : *
52 : * @stable ICU 4.2
53 : */
54 : class U_COMMON_API StringPiece : public UMemory {
55 : private:
56 : const char* ptr_;
57 : int32_t length_;
58 :
59 : public:
60 : /**
61 : * Default constructor, creates an empty StringPiece.
62 : * @stable ICU 4.2
63 : */
64 0 : StringPiece() : ptr_(NULL), length_(0) { }
65 : /**
66 : * Constructs from a NUL-terminated const char * pointer.
67 : * @param str a NUL-terminated const char * pointer
68 : * @stable ICU 4.2
69 : */
70 : StringPiece(const char* str);
71 : /**
72 : * Constructs from a std::string.
73 : * @stable ICU 4.2
74 : */
75 : StringPiece(const std::string& str)
76 : : ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { }
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 0 : 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 69 : 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 0 : 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 69 : 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 0 : 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 xdata pointer the new string data. Need not be nul terminated.
140 : * @param len the length of the new data
141 : * @stable ICU 4.8
142 : */
143 0 : void set(const char* xdata, int32_t len) { ptr_ = xdata; length_ = len; }
144 :
145 : /**
146 : * Reset the stringpiece to refer to new data.
147 : * @param str a pointer to a NUL-terminated string.
148 : * @stable ICU 4.8
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() - pos.
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 : * @stable ICU 4.8
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 : * @stable ICU 4.8
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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