1 //===- Format.h - Efficient printf-style formatting for streams -*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 10 // This file implements the format() function, which can be used with other 11 // LLVM subsystems to provide printf-style formatting. This gives all the power 12 // and risk of printf. This can be used like this (with raw_ostreams as an 13 // example): 14 // 15 // OS << "mynumber: " << format("%4.5f", 1234.412) << '\n'; 16 // 17 // Or if you prefer: 18 // 19 // OS << format("mynumber: %4.5f\n", 1234.412); 20 // 21 //===----------------------------------------------------------------------===// 22 23 #ifndef LLVM_SUPPORT_FORMAT_H 24 #define LLVM_SUPPORT_FORMAT_H 25 26 #include "llvm/ADT/ArrayRef.h" 27 #include "llvm/ADT/STLExtras.h" 28 #include "llvm/ADT/StringRef.h" 29 #include "llvm/Support/DataTypes.h" 30 #include <cassert> 31 #include <cstdio> 32 #include <tuple> 33 34 namespace llvm { 35 36 /// This is a helper class used for handling formatted output. It is the 37 /// abstract base class of a templated derived class. 38 class format_object_base { 39 protected: 40 const char *Fmt; 41 ~format_object_base() = default; // Disallow polymorphic deletion. 42 format_object_base(const format_object_base &) = default; 43 virtual void home(); // Out of line virtual method. 44 45 /// Call snprintf() for this object, on the given buffer and size. 46 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0; 47 48 public: 49 format_object_base(const char *fmt) : Fmt(fmt) {} 50 51 /// Format the object into the specified buffer. On success, this returns 52 /// the length of the formatted string. If the buffer is too small, this 53 /// returns a length to retry with, which will be larger than BufferSize. 54 unsigned print(char *Buffer, unsigned BufferSize) const { 55 assert(BufferSize && "Invalid buffer size!"); 56 57 // Print the string, leaving room for the terminating null. 58 int N = snprint(Buffer, BufferSize); 59 60 // VC++ and old GlibC return negative on overflow, just double the size. 61 if (N < 0) 62 return BufferSize * 2; 63 64 // Other implementations yield number of bytes needed, not including the 65 // final '\0'. 66 if (unsigned(N) >= BufferSize) 67 return N + 1; 68 69 // Otherwise N is the length of output (not including the final '\0'). 70 return N; 71 } 72 }; 73 74 /// These are templated helper classes used by the format function that 75 /// capture the object to be formatted and the format string. When actually 76 /// printed, this synthesizes the string into a temporary buffer provided and 77 /// returns whether or not it is big enough. 78 79 // Helper to validate that format() parameters are scalars or pointers. 80 template <typename... Args> struct validate_format_parameters; 81 template <typename Arg, typename... Args> 82 struct validate_format_parameters<Arg, Args...> { 83 static_assert(std::is_scalar<Arg>::value, 84 "format can't be used with non fundamental / non pointer type"); 85 validate_format_parameters() { validate_format_parameters<Args...>(); } 86 }; 87 template <> struct validate_format_parameters<> {}; 88 89 template <typename... Ts> 90 class format_object final : public format_object_base { 91 std::tuple<Ts...> Vals; 92 93 template <std::size_t... Is> 94 int snprint_tuple(char *Buffer, unsigned BufferSize, 95 index_sequence<Is...>) const { 96 #ifdef _MSC_VER 97 return _snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); 98 #else 99 return snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); 100 #endif 101 } 102 103 public: 104 format_object(const char *fmt, const Ts &... vals) 105 : format_object_base(fmt), Vals(vals...) { 106 validate_format_parameters<Ts...>(); 107 } 108 109 int snprint(char *Buffer, unsigned BufferSize) const override { 110 return snprint_tuple(Buffer, BufferSize, index_sequence_for<Ts...>()); 111 } 112 }; 113 114 /// These are helper functions used to produce formatted output. They use 115 /// template type deduction to construct the appropriate instance of the 116 /// format_object class to simplify their construction. 117 /// 118 /// This is typically used like: 119 /// \code 120 /// OS << format("%0.4f", myfloat) << '\n'; 121 /// \endcode 122 123 template <typename... Ts> 124 inline format_object<Ts...> format(const char *Fmt, const Ts &... Vals) { 125 return format_object<Ts...>(Fmt, Vals...); 126 } 127 128 /// This is a helper class used for left_justify() and right_justify(). 129 class FormattedString { 130 StringRef Str; 131 unsigned Width; 132 bool RightJustify; 133 friend class raw_ostream; 134 135 public: 136 FormattedString(StringRef S, unsigned W, bool R) 137 : Str(S), Width(W), RightJustify(R) { } 138 }; 139 140 /// left_justify - append spaces after string so total output is 141 /// \p Width characters. If \p Str is larger that \p Width, full string 142 /// is written with no padding. 143 inline FormattedString left_justify(StringRef Str, unsigned Width) { 144 return FormattedString(Str, Width, false); 145 } 146 147 /// right_justify - add spaces before string so total output is 148 /// \p Width characters. If \p Str is larger that \p Width, full string 149 /// is written with no padding. 150 inline FormattedString right_justify(StringRef Str, unsigned Width) { 151 return FormattedString(Str, Width, true); 152 } 153 154 /// This is a helper class used for format_hex() and format_decimal(). 155 class FormattedNumber { 156 uint64_t HexValue; 157 int64_t DecValue; 158 unsigned Width; 159 bool Hex; 160 bool Upper; 161 bool HexPrefix; 162 friend class raw_ostream; 163 164 public: 165 FormattedNumber(uint64_t HV, int64_t DV, unsigned W, bool H, bool U, 166 bool Prefix) 167 : HexValue(HV), DecValue(DV), Width(W), Hex(H), Upper(U), 168 HexPrefix(Prefix) {} 169 }; 170 171 /// format_hex - Output \p N as a fixed width hexadecimal. If number will not 172 /// fit in width, full number is still printed. Examples: 173 /// OS << format_hex(255, 4) => 0xff 174 /// OS << format_hex(255, 4, true) => 0xFF 175 /// OS << format_hex(255, 6) => 0x00ff 176 /// OS << format_hex(255, 2) => 0xff 177 inline FormattedNumber format_hex(uint64_t N, unsigned Width, 178 bool Upper = false) { 179 assert(Width <= 18 && "hex width must be <= 18"); 180 return FormattedNumber(N, 0, Width, true, Upper, true); 181 } 182 183 /// format_hex_no_prefix - Output \p N as a fixed width hexadecimal. Does not 184 /// prepend '0x' to the outputted string. If number will not fit in width, 185 /// full number is still printed. Examples: 186 /// OS << format_hex_no_prefix(255, 2) => ff 187 /// OS << format_hex_no_prefix(255, 2, true) => FF 188 /// OS << format_hex_no_prefix(255, 4) => 00ff 189 /// OS << format_hex_no_prefix(255, 1) => ff 190 inline FormattedNumber format_hex_no_prefix(uint64_t N, unsigned Width, 191 bool Upper = false) { 192 assert(Width <= 16 && "hex width must be <= 16"); 193 return FormattedNumber(N, 0, Width, true, Upper, false); 194 } 195 196 /// format_decimal - Output \p N as a right justified, fixed-width decimal. If 197 /// number will not fit in width, full number is still printed. Examples: 198 /// OS << format_decimal(0, 5) => " 0" 199 /// OS << format_decimal(255, 5) => " 255" 200 /// OS << format_decimal(-1, 3) => " -1" 201 /// OS << format_decimal(12345, 3) => "12345" 202 inline FormattedNumber format_decimal(int64_t N, unsigned Width) { 203 return FormattedNumber(0, N, Width, false, false, false); 204 } 205 206 class FormattedBytes { 207 ArrayRef<uint8_t> Bytes; 208 209 // If not None, display offsets for each line relative to starting value. 210 Optional<uint64_t> FirstByteOffset; 211 uint32_t IndentLevel; // Number of characters to indent each line. 212 uint32_t NumPerLine; // Number of bytes to show per line. 213 uint8_t ByteGroupSize; // How many hex bytes are grouped without spaces 214 bool Upper; // Show offset and hex bytes as upper case. 215 bool ASCII; // Show the ASCII bytes for the hex bytes to the right. 216 friend class raw_ostream; 217 218 public: 219 FormattedBytes(ArrayRef<uint8_t> B, uint32_t IL, Optional<uint64_t> O, 220 uint32_t NPL, uint8_t BGS, bool U, bool A) 221 : Bytes(B), FirstByteOffset(O), IndentLevel(IL), NumPerLine(NPL), 222 ByteGroupSize(BGS), Upper(U), ASCII(A) { 223 224 if (ByteGroupSize > NumPerLine) 225 ByteGroupSize = NumPerLine; 226 } 227 }; 228 229 inline FormattedBytes 230 format_bytes(ArrayRef<uint8_t> Bytes, Optional<uint64_t> FirstByteOffset = None, 231 uint32_t NumPerLine = 16, uint8_t ByteGroupSize = 4, 232 uint32_t IndentLevel = 0, bool Upper = false) { 233 return FormattedBytes(Bytes, IndentLevel, FirstByteOffset, NumPerLine, 234 ByteGroupSize, Upper, false); 235 } 236 237 inline FormattedBytes 238 format_bytes_with_ascii(ArrayRef<uint8_t> Bytes, 239 Optional<uint64_t> FirstByteOffset = None, 240 uint32_t NumPerLine = 16, uint8_t ByteGroupSize = 4, 241 uint32_t IndentLevel = 0, bool Upper = false) { 242 return FormattedBytes(Bytes, IndentLevel, FirstByteOffset, NumPerLine, 243 ByteGroupSize, Upper, true); 244 } 245 246 } // end namespace llvm 247 248 #endif 249
