1 //===- Format.h - Efficient printf-style formatting for streams -*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the format() function, which can be used with other 10 // LLVM subsystems to provide printf-style formatting. This gives all the power 11 // and risk of printf. This can be used like this (with raw_ostreams as an 12 // example): 13 // 14 // OS << "mynumber: " << format("%4.5f", 1234.412) << '\n'; 15 // 16 // Or if you prefer: 17 // 18 // OS << format("mynumber: %4.5f\n", 1234.412); 19 // 20 //===----------------------------------------------------------------------===// 21 22 #ifndef LLVM_SUPPORT_FORMAT_H 23 #define LLVM_SUPPORT_FORMAT_H 24 25 #include "llvm/ADT/ArrayRef.h" 26 #include "llvm/ADT/STLExtras.h" 27 #include "llvm/ADT/StringRef.h" 28 #include "llvm/Support/DataTypes.h" 29 #include <cassert> 30 #include <cstdio> 31 #include <tuple> 32 #include <utility> 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: format_object_base(const char * fmt)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. print(char * Buffer,unsigned 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 std::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, std::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 for left_justify, right_justify, and center_justify. 129 class FormattedString { 130 public: 131 enum Justification { JustifyNone, JustifyLeft, JustifyRight, JustifyCenter }; 132 FormattedString(StringRef S, unsigned W, Justification J) 133 : Str(S), Width(W), Justify(J) {} 134 135 private: 136 StringRef Str; 137 unsigned Width; 138 Justification Justify; 139 friend class raw_ostream; 140 }; 141 142 /// left_justify - append spaces after string so total output is 143 /// \p Width characters. If \p Str is larger that \p Width, full string 144 /// is written with no padding. 145 inline FormattedString left_justify(StringRef Str, unsigned Width) { 146 return FormattedString(Str, Width, FormattedString::JustifyLeft); 147 } 148 149 /// right_justify - add spaces before string so total output is 150 /// \p Width characters. If \p Str is larger that \p Width, full string 151 /// is written with no padding. 152 inline FormattedString right_justify(StringRef Str, unsigned Width) { 153 return FormattedString(Str, Width, FormattedString::JustifyRight); 154 } 155 156 /// center_justify - add spaces before and after string so total output is 157 /// \p Width characters. If \p Str is larger that \p Width, full string 158 /// is written with no padding. 159 inline FormattedString center_justify(StringRef Str, unsigned Width) { 160 return FormattedString(Str, Width, FormattedString::JustifyCenter); 161 } 162 163 /// This is a helper class used for format_hex() and format_decimal(). 164 class FormattedNumber { 165 uint64_t HexValue; 166 int64_t DecValue; 167 unsigned Width; 168 bool Hex; 169 bool Upper; 170 bool HexPrefix; 171 friend class raw_ostream; 172 173 public: 174 FormattedNumber(uint64_t HV, int64_t DV, unsigned W, bool H, bool U, 175 bool Prefix) 176 : HexValue(HV), DecValue(DV), Width(W), Hex(H), Upper(U), 177 HexPrefix(Prefix) {} 178 }; 179 180 /// format_hex - Output \p N as a fixed width hexadecimal. If number will not 181 /// fit in width, full number is still printed. Examples: 182 /// OS << format_hex(255, 4) => 0xff 183 /// OS << format_hex(255, 4, true) => 0xFF 184 /// OS << format_hex(255, 6) => 0x00ff 185 /// OS << format_hex(255, 2) => 0xff 186 inline FormattedNumber format_hex(uint64_t N, unsigned Width, 187 bool Upper = false) { 188 assert(Width <= 18 && "hex width must be <= 18"); 189 return FormattedNumber(N, 0, Width, true, Upper, true); 190 } 191 192 /// format_hex_no_prefix - Output \p N as a fixed width hexadecimal. Does not 193 /// prepend '0x' to the outputted string. If number will not fit in width, 194 /// full number is still printed. Examples: 195 /// OS << format_hex_no_prefix(255, 2) => ff 196 /// OS << format_hex_no_prefix(255, 2, true) => FF 197 /// OS << format_hex_no_prefix(255, 4) => 00ff 198 /// OS << format_hex_no_prefix(255, 1) => ff 199 inline FormattedNumber format_hex_no_prefix(uint64_t N, unsigned Width, 200 bool Upper = false) { 201 assert(Width <= 16 && "hex width must be <= 16"); 202 return FormattedNumber(N, 0, Width, true, Upper, false); 203 } 204 205 /// format_decimal - Output \p N as a right justified, fixed-width decimal. If 206 /// number will not fit in width, full number is still printed. Examples: 207 /// OS << format_decimal(0, 5) => " 0" 208 /// OS << format_decimal(255, 5) => " 255" 209 /// OS << format_decimal(-1, 3) => " -1" 210 /// OS << format_decimal(12345, 3) => "12345" 211 inline FormattedNumber format_decimal(int64_t N, unsigned Width) { 212 return FormattedNumber(0, N, Width, false, false, false); 213 } 214 215 class FormattedBytes { 216 ArrayRef<uint8_t> Bytes; 217 218 // If not None, display offsets for each line relative to starting value. 219 Optional<uint64_t> FirstByteOffset; 220 uint32_t IndentLevel; // Number of characters to indent each line. 221 uint32_t NumPerLine; // Number of bytes to show per line. 222 uint8_t ByteGroupSize; // How many hex bytes are grouped without spaces 223 bool Upper; // Show offset and hex bytes as upper case. 224 bool ASCII; // Show the ASCII bytes for the hex bytes to the right. 225 friend class raw_ostream; 226 227 public: 228 FormattedBytes(ArrayRef<uint8_t> B, uint32_t IL, Optional<uint64_t> O, 229 uint32_t NPL, uint8_t BGS, bool U, bool A) 230 : Bytes(B), FirstByteOffset(O), IndentLevel(IL), NumPerLine(NPL), 231 ByteGroupSize(BGS), Upper(U), ASCII(A) { 232 233 if (ByteGroupSize > NumPerLine) 234 ByteGroupSize = NumPerLine; 235 } 236 }; 237 238 inline FormattedBytes 239 format_bytes(ArrayRef<uint8_t> Bytes, 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, false); 244 } 245 246 inline FormattedBytes 247 format_bytes_with_ascii(ArrayRef<uint8_t> Bytes, 248 Optional<uint64_t> FirstByteOffset = None, 249 uint32_t NumPerLine = 16, uint8_t ByteGroupSize = 4, 250 uint32_t IndentLevel = 0, bool Upper = false) { 251 return FormattedBytes(Bytes, IndentLevel, FirstByteOffset, NumPerLine, 252 ByteGroupSize, Upper, true); 253 } 254 255 } // end namespace llvm 256 257 #endif 258