1 /* Copyright 2015 The TensorFlow Authors. All Rights Reserved. 2 3 Licensed under the Apache License, Version 2.0 (the "License"); 4 you may not use this file except in compliance with the License. 5 You may obtain a copy of the License at 6 7 http://www.apache.org/licenses/LICENSE-2.0 8 9 Unless required by applicable law or agreed to in writing, software 10 distributed under the License is distributed on an "AS IS" BASIS, 11 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 See the License for the specific language governing permissions and 13 limitations under the License. 14 ==============================================================================*/ 15 16 // #status: RECOMMENDED 17 // #category: operations on strings 18 // #summary: Merges strings or numbers with no delimiter. 19 // 20 #ifndef TENSORFLOW_LIB_STRINGS_STRCAT_H_ 21 #define TENSORFLOW_LIB_STRINGS_STRCAT_H_ 22 23 #include <string> 24 25 #include "tensorflow/core/lib/core/stringpiece.h" 26 #include "tensorflow/core/lib/strings/numbers.h" 27 #include "tensorflow/core/platform/macros.h" 28 #include "tensorflow/core/platform/types.h" 29 30 namespace Eigen { 31 struct half; 32 } 33 34 // The AlphaNum type was designed to be used as the parameter type for StrCat(). 35 // Any routine accepting either a string or a number may accept it. 36 // The basic idea is that by accepting a "const AlphaNum &" as an argument 37 // to your function, your callers will automatically convert bools, integers, 38 // and floating point values to strings for you. 39 // 40 // NOTE: Use of AlphaNum outside of the //strings package is unsupported except 41 // for the specific case of function parameters of type "AlphaNum" or "const 42 // AlphaNum &". In particular, instantiating AlphaNum directly as a stack 43 // variable is not supported. 44 // 45 // Conversion from 8-bit values is not accepted because if it were, then an 46 // attempt to pass ':' instead of ":" might result in a 58 ending up in your 47 // result. 48 // 49 // Bools convert to "0" or "1". 50 // 51 // Floating point values are converted to a string which, if passed to strtod(), 52 // would produce the exact same original double (except in case of NaN; all NaNs 53 // are considered the same value). We try to keep the string short but it's not 54 // guaranteed to be as short as possible. 55 // 56 // You can convert to Hexadecimal output rather than Decimal output using Hex. 57 // To do this, pass strings::Hex(my_int) as a parameter to StrCat. You may 58 // specify a minimum field width using a separate parameter, so the equivalent 59 // of Printf("%04x", my_int) is StrCat(Hex(my_int, strings::ZERO_PAD_4)) 60 // 61 // This class has implicit constructors. 62 namespace tensorflow { 63 namespace strings { 64 65 enum PadSpec { 66 NO_PAD = 1, 67 ZERO_PAD_2, 68 ZERO_PAD_3, 69 ZERO_PAD_4, 70 ZERO_PAD_5, 71 ZERO_PAD_6, 72 ZERO_PAD_7, 73 ZERO_PAD_8, 74 ZERO_PAD_9, 75 ZERO_PAD_10, 76 ZERO_PAD_11, 77 ZERO_PAD_12, 78 ZERO_PAD_13, 79 ZERO_PAD_14, 80 ZERO_PAD_15, 81 ZERO_PAD_16, 82 }; 83 84 struct Hex { 85 uint64 value; 86 enum PadSpec spec; 87 template <class Int> 88 explicit Hex(Int v, PadSpec s = NO_PAD) : spec(s) { 89 // Prevent sign-extension by casting integers to 90 // their unsigned counterparts. 91 static_assert( 92 sizeof(v) == 1 || sizeof(v) == 2 || sizeof(v) == 4 || sizeof(v) == 8, 93 "Unknown integer type"); 94 value = sizeof(v) == 1 95 ? static_cast<uint8>(v) 96 : sizeof(v) == 2 ? static_cast<uint16>(v) 97 : sizeof(v) == 4 ? static_cast<uint32>(v) 98 : static_cast<uint64>(v); 99 } 100 }; 101 102 class AlphaNum { 103 public: 104 // No bool ctor -- bools convert to an integral type. 105 // A bool ctor would also convert incoming pointers (bletch). 106 107 AlphaNum(int i32) // NOLINT(runtime/explicit) 108 : piece_(digits_, FastInt32ToBufferLeft(i32, digits_) - &digits_[0]) {} 109 AlphaNum(unsigned int u32) // NOLINT(runtime/explicit) 110 : piece_(digits_, FastUInt32ToBufferLeft(u32, digits_) - &digits_[0]) {} 111 AlphaNum(long x) // NOLINT(runtime/explicit) 112 : piece_(digits_, FastInt64ToBufferLeft(x, digits_) - &digits_[0]) {} 113 AlphaNum(unsigned long x) // NOLINT(runtime/explicit) 114 : piece_(digits_, FastUInt64ToBufferLeft(x, digits_) - &digits_[0]) {} 115 AlphaNum(long long int i64) // NOLINT(runtime/explicit) 116 : piece_(digits_, FastInt64ToBufferLeft(i64, digits_) - &digits_[0]) {} 117 AlphaNum(unsigned long long int u64) // NOLINT(runtime/explicit) 118 : piece_(digits_, FastUInt64ToBufferLeft(u64, digits_) - &digits_[0]) {} 119 120 AlphaNum(float f) // NOLINT(runtime/explicit) 121 : piece_(digits_, strlen(FloatToBuffer(f, digits_))) {} 122 AlphaNum(bfloat16 f) // NOLINT(runtime/explicit) 123 : piece_(digits_, strlen(FloatToBuffer(static_cast<float>(f), digits_))) { 124 } 125 AlphaNum(double f) // NOLINT(runtime/explicit) 126 : piece_(digits_, strlen(DoubleToBuffer(f, digits_))) {} 127 128 AlphaNum(const Eigen::half &f); // NOLINT(runtime/explicit) 129 AlphaNum(Hex hex); // NOLINT(runtime/explicit) 130 131 AlphaNum(const char *c_str) : piece_(c_str) {} // NOLINT(runtime/explicit) 132 AlphaNum(const StringPiece &pc) : piece_(pc) {} // NOLINT(runtime/explicit) 133 AlphaNum(const tensorflow::string &str) // NOLINT(runtime/explicit) 134 : piece_(str) {} 135 136 StringPiece::size_type size() const { return piece_.size(); } 137 const char *data() const { return piece_.data(); } 138 StringPiece Piece() const { return piece_; } 139 140 private: 141 StringPiece piece_; 142 char digits_[kFastToBufferSize]; 143 144 // Use ":" not ':' 145 AlphaNum(char c); // NOLINT(runtime/explicit) 146 147 TF_DISALLOW_COPY_AND_ASSIGN(AlphaNum); 148 }; 149 150 // ---------------------------------------------------------------------- 151 // StrCat() 152 // This merges the given strings or numbers, with no delimiter. This 153 // is designed to be the fastest possible way to construct a string out 154 // of a mix of raw C strings, StringPieces, strings, bool values, 155 // and numeric values. 156 // 157 // Don't use this for user-visible strings. The localization process 158 // works poorly on strings built up out of fragments. 159 // 160 // For clarity and performance, don't use StrCat when appending to a 161 // string. In particular, avoid using any of these (anti-)patterns: 162 // str.append(StrCat(...)) 163 // str += StrCat(...) 164 // str = StrCat(str, ...) 165 // where the last is the worse, with the potential to change a loop 166 // from a linear time operation with O(1) dynamic allocations into a 167 // quadratic time operation with O(n) dynamic allocations. StrAppend 168 // is a better choice than any of the above, subject to the restriction 169 // of StrAppend(&str, a, b, c, ...) that none of the a, b, c, ... may 170 // be a reference into str. 171 // ---------------------------------------------------------------------- 172 173 // For performance reasons, we have specializations for <= 4 args. 174 string StrCat(const AlphaNum &a) TF_MUST_USE_RESULT; 175 string StrCat(const AlphaNum &a, const AlphaNum &b) TF_MUST_USE_RESULT; 176 string StrCat(const AlphaNum &a, const AlphaNum &b, 177 const AlphaNum &c) TF_MUST_USE_RESULT; 178 string StrCat(const AlphaNum &a, const AlphaNum &b, const AlphaNum &c, 179 const AlphaNum &d) TF_MUST_USE_RESULT; 180 181 namespace internal { 182 183 // Do not call directly - this is not part of the public API. 184 string CatPieces(std::initializer_list<StringPiece> pieces); 185 void AppendPieces(string *dest, std::initializer_list<StringPiece> pieces); 186 187 } // namespace internal 188 189 // Support 5 or more arguments 190 template <typename... AV> 191 string StrCat(const AlphaNum &a, const AlphaNum &b, const AlphaNum &c, 192 const AlphaNum &d, const AlphaNum &e, 193 const AV &... args) TF_MUST_USE_RESULT; 194 195 template <typename... AV> 196 string StrCat(const AlphaNum &a, const AlphaNum &b, const AlphaNum &c, 197 const AlphaNum &d, const AlphaNum &e, const AV &... args) { 198 return internal::CatPieces({a.Piece(), b.Piece(), c.Piece(), d.Piece(), 199 e.Piece(), 200 static_cast<const AlphaNum &>(args).Piece()...}); 201 } 202 203 // ---------------------------------------------------------------------- 204 // StrAppend() 205 // Same as above, but adds the output to the given string. 206 // WARNING: For speed, StrAppend does not try to check each of its input 207 // arguments to be sure that they are not a subset of the string being 208 // appended to. That is, while this will work: 209 // 210 // string s = "foo"; 211 // s += s; 212 // 213 // This will not (necessarily) work: 214 // 215 // string s = "foo"; 216 // StrAppend(&s, s); 217 // 218 // Note: while StrCat supports appending up to 26 arguments, StrAppend 219 // is currently limited to 9. That's rarely an issue except when 220 // automatically transforming StrCat to StrAppend, and can easily be 221 // worked around as consecutive calls to StrAppend are quite efficient. 222 // ---------------------------------------------------------------------- 223 224 void StrAppend(string *dest, const AlphaNum &a); 225 void StrAppend(string *dest, const AlphaNum &a, const AlphaNum &b); 226 void StrAppend(string *dest, const AlphaNum &a, const AlphaNum &b, 227 const AlphaNum &c); 228 void StrAppend(string *dest, const AlphaNum &a, const AlphaNum &b, 229 const AlphaNum &c, const AlphaNum &d); 230 231 // Support 5 or more arguments 232 template <typename... AV> 233 inline void StrAppend(string *dest, const AlphaNum &a, const AlphaNum &b, 234 const AlphaNum &c, const AlphaNum &d, const AlphaNum &e, 235 const AV &... args) { 236 internal::AppendPieces(dest, 237 {a.Piece(), b.Piece(), c.Piece(), d.Piece(), e.Piece(), 238 static_cast<const AlphaNum &>(args).Piece()...}); 239 } 240 241 } // namespace strings 242 } // namespace tensorflow 243 244 #endif // TENSORFLOW_LIB_STRINGS_STRCAT_H_ 245
