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 <optional> 32 #include <tuple> 33 #include <utility> 34 35 namespace llvm { 36 37 /// This is a helper class used for handling formatted output. It is the 38 /// abstract base class of a templated derived class. 39 class format_object_base { 40 protected: 41 const char *Fmt; 42 ~format_object_base() = default; // Disallow polymorphic deletion. 43 format_object_base(const format_object_base &) = default; 44 virtual void home(); // Out of line virtual method. 45 46 /// Call snprintf() for this object, on the given buffer and size. 47 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0; 48 49 public: format_object_base(const char * fmt)50 format_object_base(const char *fmt) : Fmt(fmt) {} 51 52 /// Format the object into the specified buffer. On success, this returns 53 /// the length of the formatted string. If the buffer is too small, this 54 /// returns a length to retry with, which will be larger than BufferSize. print(char * Buffer,unsigned BufferSize)55 unsigned print(char *Buffer, unsigned BufferSize) const { 56 assert(BufferSize && "Invalid buffer size!"); 57 58 // Print the string, leaving room for the terminating null. 59 int N = snprint(Buffer, BufferSize); 60 61 // VC++ and old GlibC return negative on overflow, just double the size. 62 if (N < 0) 63 return BufferSize * 2; 64 65 // Other implementations yield number of bytes needed, not including the 66 // final '\0'. 67 if (unsigned(N) >= BufferSize) 68 return N + 1; 69 70 // Otherwise N is the length of output (not including the final '\0'). 71 return N; 72 } 73 }; 74 75 /// These are templated helper classes used by the format function that 76 /// capture the object to be formatted and the format string. When actually 77 /// printed, this synthesizes the string into a temporary buffer provided and 78 /// returns whether or not it is big enough. 79 80 // Helper to validate that format() parameters are scalars or pointers. 81 template <typename... Args> struct validate_format_parameters; 82 template <typename Arg, typename... Args> 83 struct validate_format_parameters<Arg, Args...> { 84 static_assert(std::is_scalar_v<Arg>, 85 "format can't be used with non fundamental / non pointer type"); 86 validate_format_parameters() { validate_format_parameters<Args...>(); } 87 }; 88 template <> struct validate_format_parameters<> {}; 89 90 template <typename... Ts> 91 class format_object final : public format_object_base { 92 std::tuple<Ts...> Vals; 93 94 template <std::size_t... Is> 95 int snprint_tuple(char *Buffer, unsigned BufferSize, 96 std::index_sequence<Is...>) const { 97 #ifdef _MSC_VER 98 return _snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); 99 #else 100 return snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); 101 #endif 102 } 103 104 public: 105 format_object(const char *fmt, const Ts &... vals) 106 : format_object_base(fmt), Vals(vals...) { 107 validate_format_parameters<Ts...>(); 108 } 109 110 int snprint(char *Buffer, unsigned BufferSize) const override { 111 return snprint_tuple(Buffer, BufferSize, std::index_sequence_for<Ts...>()); 112 } 113 }; 114 115 /// These are helper functions used to produce formatted output. They use 116 /// template type deduction to construct the appropriate instance of the 117 /// format_object class to simplify their construction. 118 /// 119 /// This is typically used like: 120 /// \code 121 /// OS << format("%0.4f", myfloat) << '\n'; 122 /// \endcode 123 124 template <typename... Ts> 125 inline format_object<Ts...> format(const char *Fmt, const Ts &... Vals) { 126 return format_object<Ts...>(Fmt, Vals...); 127 } 128 129 /// This is a helper class for left_justify, right_justify, and center_justify. 130 class FormattedString { 131 public: 132 enum Justification { JustifyNone, JustifyLeft, JustifyRight, JustifyCenter }; 133 FormattedString(StringRef S, unsigned W, Justification J) 134 : Str(S), Width(W), Justify(J) {} 135 136 private: 137 StringRef Str; 138 unsigned Width; 139 Justification Justify; 140 friend class raw_ostream; 141 }; 142 143 /// left_justify - append spaces after string so total output is 144 /// \p Width characters. If \p Str is larger that \p Width, full string 145 /// is written with no padding. 146 inline FormattedString left_justify(StringRef Str, unsigned Width) { 147 return FormattedString(Str, Width, FormattedString::JustifyLeft); 148 } 149 150 /// right_justify - add spaces before string so total output is 151 /// \p Width characters. If \p Str is larger that \p Width, full string 152 /// is written with no padding. 153 inline FormattedString right_justify(StringRef Str, unsigned Width) { 154 return FormattedString(Str, Width, FormattedString::JustifyRight); 155 } 156 157 /// center_justify - add spaces before and after string so total output is 158 /// \p Width characters. If \p Str is larger that \p Width, full string 159 /// is written with no padding. 160 inline FormattedString center_justify(StringRef Str, unsigned Width) { 161 return FormattedString(Str, Width, FormattedString::JustifyCenter); 162 } 163 164 /// This is a helper class used for format_hex() and format_decimal(). 165 class FormattedNumber { 166 uint64_t HexValue; 167 int64_t DecValue; 168 unsigned Width; 169 bool Hex; 170 bool Upper; 171 bool HexPrefix; 172 friend class raw_ostream; 173 174 public: 175 FormattedNumber(uint64_t HV, int64_t DV, unsigned W, bool H, bool U, 176 bool Prefix) 177 : HexValue(HV), DecValue(DV), Width(W), Hex(H), Upper(U), 178 HexPrefix(Prefix) {} 179 }; 180 181 /// format_hex - Output \p N as a fixed width hexadecimal. If number will not 182 /// fit in width, full number is still printed. Examples: 183 /// OS << format_hex(255, 4) => 0xff 184 /// OS << format_hex(255, 4, true) => 0xFF 185 /// OS << format_hex(255, 6) => 0x00ff 186 /// OS << format_hex(255, 2) => 0xff 187 inline FormattedNumber format_hex(uint64_t N, unsigned Width, 188 bool Upper = false) { 189 assert(Width <= 18 && "hex width must be <= 18"); 190 return FormattedNumber(N, 0, Width, true, Upper, true); 191 } 192 193 /// format_hex_no_prefix - Output \p N as a fixed width hexadecimal. Does not 194 /// prepend '0x' to the outputted string. If number will not fit in width, 195 /// full number is still printed. Examples: 196 /// OS << format_hex_no_prefix(255, 2) => ff 197 /// OS << format_hex_no_prefix(255, 2, true) => FF 198 /// OS << format_hex_no_prefix(255, 4) => 00ff 199 /// OS << format_hex_no_prefix(255, 1) => ff 200 inline FormattedNumber format_hex_no_prefix(uint64_t N, unsigned Width, 201 bool Upper = false) { 202 assert(Width <= 16 && "hex width must be <= 16"); 203 return FormattedNumber(N, 0, Width, true, Upper, false); 204 } 205 206 /// format_decimal - Output \p N as a right justified, fixed-width decimal. If 207 /// number will not fit in width, full number is still printed. Examples: 208 /// OS << format_decimal(0, 5) => " 0" 209 /// OS << format_decimal(255, 5) => " 255" 210 /// OS << format_decimal(-1, 3) => " -1" 211 /// OS << format_decimal(12345, 3) => "12345" 212 inline FormattedNumber format_decimal(int64_t N, unsigned Width) { 213 return FormattedNumber(0, N, Width, false, false, false); 214 } 215 216 class FormattedBytes { 217 ArrayRef<uint8_t> Bytes; 218 219 // If not std::nullopt, display offsets for each line relative to starting 220 // value. 221 std::optional<uint64_t> FirstByteOffset; 222 uint32_t IndentLevel; // Number of characters to indent each line. 223 uint32_t NumPerLine; // Number of bytes to show per line. 224 uint8_t ByteGroupSize; // How many hex bytes are grouped without spaces 225 bool Upper; // Show offset and hex bytes as upper case. 226 bool ASCII; // Show the ASCII bytes for the hex bytes to the right. 227 friend class raw_ostream; 228 229 public: 230 FormattedBytes(ArrayRef<uint8_t> B, uint32_t IL, std::optional<uint64_t> O, 231 uint32_t NPL, uint8_t BGS, bool U, bool A) 232 : Bytes(B), FirstByteOffset(O), IndentLevel(IL), NumPerLine(NPL), 233 ByteGroupSize(BGS), Upper(U), ASCII(A) { 234 235 if (ByteGroupSize > NumPerLine) 236 ByteGroupSize = NumPerLine; 237 } 238 }; 239 240 inline FormattedBytes 241 format_bytes(ArrayRef<uint8_t> Bytes, 242 std::optional<uint64_t> FirstByteOffset = std::nullopt, 243 uint32_t NumPerLine = 16, uint8_t ByteGroupSize = 4, 244 uint32_t IndentLevel = 0, bool Upper = false) { 245 return FormattedBytes(Bytes, IndentLevel, FirstByteOffset, NumPerLine, 246 ByteGroupSize, Upper, false); 247 } 248 249 inline FormattedBytes 250 format_bytes_with_ascii(ArrayRef<uint8_t> Bytes, 251 std::optional<uint64_t> FirstByteOffset = std::nullopt, 252 uint32_t NumPerLine = 16, uint8_t ByteGroupSize = 4, 253 uint32_t IndentLevel = 0, bool Upper = false) { 254 return FormattedBytes(Bytes, IndentLevel, FirstByteOffset, NumPerLine, 255 ByteGroupSize, Upper, true); 256 } 257 258 } // end namespace llvm 259 260 #endif 261