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 33 namespace llvm { 34 35 /// This is a helper class used for handling formatted output. It is the 36 /// abstract base class of a templated derived class. 37 class format_object_base { 38 protected: 39 const char *Fmt; 40 ~format_object_base() = default; // Disallow polymorphic deletion. 41 format_object_base(const format_object_base &) = default; 42 virtual void home(); // Out of line virtual method. 43 44 /// Call snprintf() for this object, on the given buffer and size. 45 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0; 46 47 public: format_object_base(const char * fmt)48 format_object_base(const char *fmt) : Fmt(fmt) {} 49 50 /// Format the object into the specified buffer. On success, this returns 51 /// the length of the formatted string. If the buffer is too small, this 52 /// returns a length to retry with, which will be larger than BufferSize. print(char * Buffer,unsigned BufferSize)53 unsigned print(char *Buffer, unsigned BufferSize) const { 54 assert(BufferSize && "Invalid buffer size!"); 55 56 // Print the string, leaving room for the terminating null. 57 int N = snprint(Buffer, BufferSize); 58 59 // VC++ and old GlibC return negative on overflow, just double the size. 60 if (N < 0) 61 return BufferSize * 2; 62 63 // Other implementations yield number of bytes needed, not including the 64 // final '\0'. 65 if (unsigned(N) >= BufferSize) 66 return N + 1; 67 68 // Otherwise N is the length of output (not including the final '\0'). 69 return N; 70 } 71 }; 72 73 /// These are templated helper classes used by the format function that 74 /// capture the object to be formatted and the format string. When actually 75 /// printed, this synthesizes the string into a temporary buffer provided and 76 /// returns whether or not it is big enough. 77 78 // Helper to validate that format() parameters are scalars or pointers. 79 template <typename... Args> struct validate_format_parameters; 80 template <typename Arg, typename... Args> 81 struct validate_format_parameters<Arg, Args...> { 82 static_assert(std::is_scalar<Arg>::value, 83 "format can't be used with non fundamental / non pointer type"); 84 validate_format_parameters() { validate_format_parameters<Args...>(); } 85 }; 86 template <> struct validate_format_parameters<> {}; 87 88 template <typename... Ts> 89 class format_object final : public format_object_base { 90 std::tuple<Ts...> Vals; 91 92 template <std::size_t... Is> 93 int snprint_tuple(char *Buffer, unsigned BufferSize, 94 index_sequence<Is...>) const { 95 #ifdef _MSC_VER 96 return _snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); 97 #else 98 return snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...); 99 #endif 100 } 101 102 public: 103 format_object(const char *fmt, const Ts &... vals) 104 : format_object_base(fmt), Vals(vals...) { 105 validate_format_parameters<Ts...>(); 106 } 107 108 int snprint(char *Buffer, unsigned BufferSize) const override { 109 return snprint_tuple(Buffer, BufferSize, index_sequence_for<Ts...>()); 110 } 111 }; 112 113 /// These are helper functions used to produce formatted output. They use 114 /// template type deduction to construct the appropriate instance of the 115 /// format_object class to simplify their construction. 116 /// 117 /// This is typically used like: 118 /// \code 119 /// OS << format("%0.4f", myfloat) << '\n'; 120 /// \endcode 121 122 template <typename... Ts> 123 inline format_object<Ts...> format(const char *Fmt, const Ts &... Vals) { 124 return format_object<Ts...>(Fmt, Vals...); 125 } 126 127 /// This is a helper class for left_justify, right_justify, and center_justify. 128 class FormattedString { 129 public: 130 enum Justification { JustifyNone, JustifyLeft, JustifyRight, JustifyCenter }; 131 FormattedString(StringRef S, unsigned W, Justification J) 132 : Str(S), Width(W), Justify(J) {} 133 134 private: 135 StringRef Str; 136 unsigned Width; 137 Justification Justify; 138 friend class raw_ostream; 139 }; 140 141 /// left_justify - append spaces after string so total output is 142 /// \p Width characters. If \p Str is larger that \p Width, full string 143 /// is written with no padding. 144 inline FormattedString left_justify(StringRef Str, unsigned Width) { 145 return FormattedString(Str, Width, FormattedString::JustifyLeft); 146 } 147 148 /// right_justify - add spaces before string so total output is 149 /// \p Width characters. If \p Str is larger that \p Width, full string 150 /// is written with no padding. 151 inline FormattedString right_justify(StringRef Str, unsigned Width) { 152 return FormattedString(Str, Width, FormattedString::JustifyRight); 153 } 154 155 /// center_justify - add spaces before and after string so total output is 156 /// \p Width characters. If \p Str is larger that \p Width, full string 157 /// is written with no padding. 158 inline FormattedString center_justify(StringRef Str, unsigned Width) { 159 return FormattedString(Str, Width, FormattedString::JustifyCenter); 160 } 161 162 /// This is a helper class used for format_hex() and format_decimal(). 163 class FormattedNumber { 164 uint64_t HexValue; 165 int64_t DecValue; 166 unsigned Width; 167 bool Hex; 168 bool Upper; 169 bool HexPrefix; 170 friend class raw_ostream; 171 172 public: 173 FormattedNumber(uint64_t HV, int64_t DV, unsigned W, bool H, bool U, 174 bool Prefix) 175 : HexValue(HV), DecValue(DV), Width(W), Hex(H), Upper(U), 176 HexPrefix(Prefix) {} 177 }; 178 179 /// format_hex - Output \p N as a fixed width hexadecimal. If number will not 180 /// fit in width, full number is still printed. Examples: 181 /// OS << format_hex(255, 4) => 0xff 182 /// OS << format_hex(255, 4, true) => 0xFF 183 /// OS << format_hex(255, 6) => 0x00ff 184 /// OS << format_hex(255, 2) => 0xff 185 inline FormattedNumber format_hex(uint64_t N, unsigned Width, 186 bool Upper = false) { 187 assert(Width <= 18 && "hex width must be <= 18"); 188 return FormattedNumber(N, 0, Width, true, Upper, true); 189 } 190 191 /// format_hex_no_prefix - Output \p N as a fixed width hexadecimal. Does not 192 /// prepend '0x' to the outputted string. If number will not fit in width, 193 /// full number is still printed. Examples: 194 /// OS << format_hex_no_prefix(255, 2) => ff 195 /// OS << format_hex_no_prefix(255, 2, true) => FF 196 /// OS << format_hex_no_prefix(255, 4) => 00ff 197 /// OS << format_hex_no_prefix(255, 1) => ff 198 inline FormattedNumber format_hex_no_prefix(uint64_t N, unsigned Width, 199 bool Upper = false) { 200 assert(Width <= 16 && "hex width must be <= 16"); 201 return FormattedNumber(N, 0, Width, true, Upper, false); 202 } 203 204 /// format_decimal - Output \p N as a right justified, fixed-width decimal. If 205 /// number will not fit in width, full number is still printed. Examples: 206 /// OS << format_decimal(0, 5) => " 0" 207 /// OS << format_decimal(255, 5) => " 255" 208 /// OS << format_decimal(-1, 3) => " -1" 209 /// OS << format_decimal(12345, 3) => "12345" 210 inline FormattedNumber format_decimal(int64_t N, unsigned Width) { 211 return FormattedNumber(0, N, Width, false, false, false); 212 } 213 214 class FormattedBytes { 215 ArrayRef<uint8_t> Bytes; 216 217 // If not None, display offsets for each line relative to starting value. 218 Optional<uint64_t> FirstByteOffset; 219 uint32_t IndentLevel; // Number of characters to indent each line. 220 uint32_t NumPerLine; // Number of bytes to show per line. 221 uint8_t ByteGroupSize; // How many hex bytes are grouped without spaces 222 bool Upper; // Show offset and hex bytes as upper case. 223 bool ASCII; // Show the ASCII bytes for the hex bytes to the right. 224 friend class raw_ostream; 225 226 public: 227 FormattedBytes(ArrayRef<uint8_t> B, uint32_t IL, Optional<uint64_t> O, 228 uint32_t NPL, uint8_t BGS, bool U, bool A) 229 : Bytes(B), FirstByteOffset(O), IndentLevel(IL), NumPerLine(NPL), 230 ByteGroupSize(BGS), Upper(U), ASCII(A) { 231 232 if (ByteGroupSize > NumPerLine) 233 ByteGroupSize = NumPerLine; 234 } 235 }; 236 237 inline FormattedBytes 238 format_bytes(ArrayRef<uint8_t> Bytes, Optional<uint64_t> FirstByteOffset = None, 239 uint32_t NumPerLine = 16, uint8_t ByteGroupSize = 4, 240 uint32_t IndentLevel = 0, bool Upper = false) { 241 return FormattedBytes(Bytes, IndentLevel, FirstByteOffset, NumPerLine, 242 ByteGroupSize, Upper, false); 243 } 244 245 inline FormattedBytes 246 format_bytes_with_ascii(ArrayRef<uint8_t> Bytes, 247 Optional<uint64_t> FirstByteOffset = None, 248 uint32_t NumPerLine = 16, uint8_t ByteGroupSize = 4, 249 uint32_t IndentLevel = 0, bool Upper = false) { 250 return FormattedBytes(Bytes, IndentLevel, FirstByteOffset, NumPerLine, 251 ByteGroupSize, Upper, true); 252 } 253 254 } // end namespace llvm 255 256 #endif 257