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
36U_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 */
54class 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 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 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 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 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 */
208U_EXPORT UBool U_EXPORT2
209operator==(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 */
218inline UBool operator!=(const StringPiece& x, const StringPiece& y) {
219 return !(x == y);
220}
221
222U_NAMESPACE_END
223
224#endif // __STRINGPIECE_H__
225