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1 // Copyright (C) 2009-2013, International Business Machines |
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2 // Corporation and others. All Rights Reserved. |
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3 // |
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4 // Copyright 2001 and onwards Google Inc. |
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5 // Author: Sanjay Ghemawat |
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6 |
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7 // This code is a contribution of Google code, and the style used here is |
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8 // a compromise between the original Google code and the ICU coding guidelines. |
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9 // For example, data types are ICU-ified (size_t,int->int32_t), |
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10 // and API comments doxygen-ified, but function names and behavior are |
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11 // as in the original, if possible. |
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12 // Assertion-style error handling, not available in ICU, was changed to |
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13 // parameter "pinning" similar to UnicodeString. |
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14 // |
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15 // In addition, this is only a partial port of the original Google code, |
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16 // limited to what was needed so far. The (nearly) complete original code |
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17 // is in the ICU svn repository at icuhtml/trunk/design/strings/contrib |
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18 // (see ICU ticket 6765, r25517). |
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19 |
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20 #ifndef __STRINGPIECE_H__ |
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21 #define __STRINGPIECE_H__ |
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22 |
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23 /** |
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24 * \file |
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25 * \brief C++ API: StringPiece: Read-only byte string wrapper class. |
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26 */ |
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27 |
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28 #include "unicode/utypes.h" |
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29 #include "unicode/uobject.h" |
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30 #include "unicode/std_string.h" |
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31 |
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32 // Arghh! I wish C++ literals were "string". |
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33 |
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34 U_NAMESPACE_BEGIN |
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35 |
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36 /** |
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37 * A string-like object that points to a sized piece of memory. |
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38 * |
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39 * We provide non-explicit singleton constructors so users can pass |
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40 * in a "const char*" or a "string" wherever a "StringPiece" is |
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41 * expected. |
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42 * |
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43 * Functions or methods may use const StringPiece& parameters to accept either |
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44 * a "const char*" or a "string" value that will be implicitly converted to |
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45 * a StringPiece. |
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46 * |
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47 * Systematic usage of StringPiece is encouraged as it will reduce unnecessary |
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48 * conversions from "const char*" to "string" and back again. |
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49 * |
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50 * @stable ICU 4.2 |
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51 */ |
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52 class U_COMMON_API StringPiece : public UMemory { |
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53 private: |
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54 const char* ptr_; |
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55 int32_t length_; |
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56 |
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57 public: |
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58 /** |
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59 * Default constructor, creates an empty StringPiece. |
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60 * @stable ICU 4.2 |
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61 */ |
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62 StringPiece() : ptr_(NULL), length_(0) { } |
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63 /** |
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64 * Constructs from a NUL-terminated const char * pointer. |
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65 * @param str a NUL-terminated const char * pointer |
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66 * @stable ICU 4.2 |
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67 */ |
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68 StringPiece(const char* str); |
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69 #if U_HAVE_STD_STRING |
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70 /** |
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71 * Constructs from a std::string. |
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72 * @stable ICU 4.2 |
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73 */ |
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74 StringPiece(const std::string& str) |
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75 : ptr_(str.data()), length_(static_cast<int32_t>(str.size())) { } |
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76 #endif |
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77 /** |
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78 * Constructs from a const char * pointer and a specified length. |
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79 * @param offset a const char * pointer (need not be terminated) |
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80 * @param len the length of the string; must be non-negative |
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81 * @stable ICU 4.2 |
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82 */ |
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83 StringPiece(const char* offset, int32_t len) : ptr_(offset), length_(len) { } |
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84 /** |
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85 * Substring of another StringPiece. |
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86 * @param x the other StringPiece |
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87 * @param pos start position in x; must be non-negative and <= x.length(). |
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88 * @stable ICU 4.2 |
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89 */ |
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90 StringPiece(const StringPiece& x, int32_t pos); |
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91 /** |
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92 * Substring of another StringPiece. |
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93 * @param x the other StringPiece |
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94 * @param pos start position in x; must be non-negative and <= x.length(). |
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95 * @param len length of the substring; |
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96 * must be non-negative and will be pinned to at most x.length() - pos. |
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97 * @stable ICU 4.2 |
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98 */ |
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99 StringPiece(const StringPiece& x, int32_t pos, int32_t len); |
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100 |
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101 /** |
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102 * Returns the string pointer. May be NULL if it is empty. |
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103 * |
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104 * data() may return a pointer to a buffer with embedded NULs, and the |
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105 * returned buffer may or may not be null terminated. Therefore it is |
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106 * typically a mistake to pass data() to a routine that expects a NUL |
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107 * terminated string. |
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108 * @return the string pointer |
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109 * @stable ICU 4.2 |
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110 */ |
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111 const char* data() const { return ptr_; } |
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112 /** |
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113 * Returns the string length. Same as length(). |
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114 * @return the string length |
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115 * @stable ICU 4.2 |
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116 */ |
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117 int32_t size() const { return length_; } |
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118 /** |
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119 * Returns the string length. Same as size(). |
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120 * @return the string length |
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121 * @stable ICU 4.2 |
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122 */ |
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123 int32_t length() const { return length_; } |
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124 /** |
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125 * Returns whether the string is empty. |
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126 * @return TRUE if the string is empty |
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127 * @stable ICU 4.2 |
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128 */ |
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129 UBool empty() const { return length_ == 0; } |
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130 |
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131 /** |
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132 * Sets to an empty string. |
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133 * @stable ICU 4.2 |
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134 */ |
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135 void clear() { ptr_ = NULL; length_ = 0; } |
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136 |
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137 /** |
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138 * Reset the stringpiece to refer to new data. |
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139 * @param xdata pointer the new string data. Need not be nul terminated. |
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140 * @param len the length of the new data |
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141 * @stable ICU 4.8 |
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142 */ |
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143 void set(const char* xdata, int32_t len) { ptr_ = xdata; length_ = len; } |
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144 |
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145 /** |
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146 * Reset the stringpiece to refer to new data. |
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147 * @param str a pointer to a NUL-terminated string. |
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148 * @stable ICU 4.8 |
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149 */ |
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150 void set(const char* str); |
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151 |
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152 /** |
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153 * Removes the first n string units. |
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154 * @param n prefix length, must be non-negative and <=length() |
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155 * @stable ICU 4.2 |
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156 */ |
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157 void remove_prefix(int32_t n) { |
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158 if (n >= 0) { |
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159 if (n > length_) { |
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160 n = length_; |
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161 } |
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162 ptr_ += n; |
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163 length_ -= n; |
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164 } |
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165 } |
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166 |
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167 /** |
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168 * Removes the last n string units. |
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169 * @param n suffix length, must be non-negative and <=length() |
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170 * @stable ICU 4.2 |
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171 */ |
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172 void remove_suffix(int32_t n) { |
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173 if (n >= 0) { |
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174 if (n <= length_) { |
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175 length_ -= n; |
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176 } else { |
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177 length_ = 0; |
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178 } |
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179 } |
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180 } |
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181 |
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182 /** |
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183 * Maximum integer, used as a default value for substring methods. |
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184 * @stable ICU 4.2 |
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185 */ |
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186 static const int32_t npos; // = 0x7fffffff; |
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187 |
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188 /** |
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189 * Returns a substring of this StringPiece. |
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190 * @param pos start position; must be non-negative and <= length(). |
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191 * @param len length of the substring; |
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192 * must be non-negative and will be pinned to at most length() - pos. |
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193 * @return the substring StringPiece |
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194 * @stable ICU 4.2 |
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195 */ |
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196 StringPiece substr(int32_t pos, int32_t len = npos) const { |
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197 return StringPiece(*this, pos, len); |
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198 } |
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199 }; |
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200 |
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201 /** |
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202 * Global operator == for StringPiece |
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203 * @param x The first StringPiece to compare. |
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204 * @param y The second StringPiece to compare. |
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205 * @return TRUE if the string data is equal |
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206 * @stable ICU 4.8 |
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207 */ |
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208 U_EXPORT UBool U_EXPORT2 |
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209 operator==(const StringPiece& x, const StringPiece& y); |
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210 |
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211 /** |
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212 * Global operator != for StringPiece |
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213 * @param x The first StringPiece to compare. |
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214 * @param y The second StringPiece to compare. |
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215 * @return TRUE if the string data is not equal |
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216 * @stable ICU 4.8 |
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217 */ |
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218 inline UBool operator!=(const StringPiece& x, const StringPiece& y) { |
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219 return !(x == y); |
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220 } |
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221 |
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222 U_NAMESPACE_END |
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223 |
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224 #endif // __STRINGPIECE_H__ |