1 //===- Format.h - Efficient printf-style formatting for streams -*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
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
15 // OS << "mynumber: " << format("%4.5f", 1234.412) << '\n';
19 // OS << format("mynumber: %4.5f\n", 1234.412);
21 //===----------------------------------------------------------------------===//
23 #ifndef LLVM_SUPPORT_FORMAT_H
24 #define LLVM_SUPPORT_FORMAT_H
26 #include "llvm/ADT/StringRef.h"
27 #include "llvm/Support/DataTypes.h"
31 // FIXME: This define is wrong:
32 // - _snprintf does not guarantee that trailing null is always added - if
33 // there is no space for null, it does not report any error.
34 // - According to C++ standard, snprintf should be visible in the 'std'
35 // namespace - this define makes this impossible.
36 #define snprintf _snprintf
41 /// This is a helper class used for handling formatted output. It is the
42 /// abstract base class of a templated derived class.
43 class format_object_base {
46 ~format_object_base() {} // Disallow polymorphic deletion.
47 virtual void home(); // Out of line virtual method.
49 /// Call snprintf() for this object, on the given buffer and size.
50 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0;
53 format_object_base(const char *fmt) : Fmt(fmt) {}
55 /// Format the object into the specified buffer. On success, this returns
56 /// the length of the formatted string. If the buffer is too small, this
57 /// returns a length to retry with, which will be larger than BufferSize.
58 unsigned print(char *Buffer, unsigned BufferSize) const {
59 assert(BufferSize && "Invalid buffer size!");
61 // Print the string, leaving room for the terminating null.
62 int N = snprint(Buffer, BufferSize);
64 // VC++ and old GlibC return negative on overflow, just double the size.
66 return BufferSize * 2;
68 // Other implementations yield number of bytes needed, not including the
70 if (unsigned(N) >= BufferSize)
73 // Otherwise N is the length of output (not including the final '\0').
78 /// These are templated helper classes used by the format function that
79 /// capture the object to be formated and the format string. When actually
80 /// printed, this synthesizes the string into a temporary buffer provided and
81 /// returns whether or not it is big enough.
84 class format_object1 final : public format_object_base {
87 format_object1(const char *fmt, const T &val)
88 : format_object_base(fmt), Val(val) {
91 int snprint(char *Buffer, unsigned BufferSize) const override {
92 return snprintf(Buffer, BufferSize, Fmt, Val);
96 template <typename T1, typename T2>
97 class format_object2 final : public format_object_base {
101 format_object2(const char *fmt, const T1 &val1, const T2 &val2)
102 : format_object_base(fmt), Val1(val1), Val2(val2) {
105 int snprint(char *Buffer, unsigned BufferSize) const override {
106 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2);
110 template <typename T1, typename T2, typename T3>
111 class format_object3 final : public format_object_base {
116 format_object3(const char *fmt, const T1 &val1, const T2 &val2,const T3 &val3)
117 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3) {
120 int snprint(char *Buffer, unsigned BufferSize) const override {
121 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3);
125 template <typename T1, typename T2, typename T3, typename T4>
126 class format_object4 final : public format_object_base {
132 format_object4(const char *fmt, const T1 &val1, const T2 &val2,
133 const T3 &val3, const T4 &val4)
134 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4) {
137 int snprint(char *Buffer, unsigned BufferSize) const override {
138 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4);
142 template <typename T1, typename T2, typename T3, typename T4, typename T5>
143 class format_object5 final : public format_object_base {
150 format_object5(const char *fmt, const T1 &val1, const T2 &val2,
151 const T3 &val3, const T4 &val4, const T5 &val5)
152 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4),
156 int snprint(char *Buffer, unsigned BufferSize) const override {
157 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5);
161 template <typename T1, typename T2, typename T3, typename T4, typename T5,
163 class format_object6 final : public format_object_base {
171 format_object6(const char *Fmt, const T1 &Val1, const T2 &Val2,
172 const T3 &Val3, const T4 &Val4, const T5 &Val5, const T6 &Val6)
173 : format_object_base(Fmt), Val1(Val1), Val2(Val2), Val3(Val3), Val4(Val4),
174 Val5(Val5), Val6(Val6) { }
176 int snprint(char *Buffer, unsigned BufferSize) const override {
177 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5, Val6);
181 /// These are helper functions used to produce formatted output. They use
182 /// template type deduction to construct the appropriate instance of the
183 /// format_object class to simplify their construction.
185 /// This is typically used like:
187 /// OS << format("%0.4f", myfloat) << '\n';
190 template <typename T>
191 inline format_object1<T> format(const char *Fmt, const T &Val) {
192 return format_object1<T>(Fmt, Val);
195 template <typename T1, typename T2>
196 inline format_object2<T1, T2> format(const char *Fmt, const T1 &Val1,
198 return format_object2<T1, T2>(Fmt, Val1, Val2);
201 template <typename T1, typename T2, typename T3>
202 inline format_object3<T1, T2, T3> format(const char *Fmt, const T1 &Val1,
203 const T2 &Val2, const T3 &Val3) {
204 return format_object3<T1, T2, T3>(Fmt, Val1, Val2, Val3);
207 template <typename T1, typename T2, typename T3, typename T4>
208 inline format_object4<T1, T2, T3, T4> format(const char *Fmt, const T1 &Val1,
209 const T2 &Val2, const T3 &Val3,
211 return format_object4<T1, T2, T3, T4>(Fmt, Val1, Val2, Val3, Val4);
214 template <typename T1, typename T2, typename T3, typename T4, typename T5>
215 inline format_object5<T1, T2, T3, T4, T5> format(const char *Fmt,const T1 &Val1,
216 const T2 &Val2, const T3 &Val3,
217 const T4 &Val4, const T5 &Val5) {
218 return format_object5<T1, T2, T3, T4, T5>(Fmt, Val1, Val2, Val3, Val4, Val5);
221 template <typename T1, typename T2, typename T3, typename T4, typename T5,
223 inline format_object6<T1, T2, T3, T4, T5, T6>
224 format(const char *Fmt, const T1 &Val1, const T2 &Val2, const T3 &Val3,
225 const T4 &Val4, const T5 &Val5, const T6 &Val6) {
226 return format_object6<T1, T2, T3, T4, T5, T6>(Fmt, Val1, Val2, Val3, Val4,
230 /// This is a helper class used for left_justify() and right_justify().
231 class FormattedString {
235 friend class raw_ostream;
237 FormattedString(StringRef S, unsigned W, bool R)
238 : Str(S), Width(W), RightJustify(R) { }
241 /// left_justify - append spaces after string so total output is
242 /// \p Width characters. If \p Str is larger that \p Width, full string
243 /// is written with no padding.
244 inline FormattedString left_justify(StringRef Str, unsigned Width) {
245 return FormattedString(Str, Width, false);
248 /// right_justify - add spaces before string so total output is
249 /// \p Width characters. If \p Str is larger that \p Width, full string
250 /// is written with no padding.
251 inline FormattedString right_justify(StringRef Str, unsigned Width) {
252 return FormattedString(Str, Width, true);
255 /// This is a helper class used for format_hex() and format_decimal().
256 class FormattedNumber {
263 friend class raw_ostream;
265 FormattedNumber(uint64_t HV, int64_t DV, unsigned W, bool H, bool U,
267 : HexValue(HV), DecValue(DV), Width(W), Hex(H), Upper(U),
271 /// format_hex - Output \p N as a fixed width hexadecimal. If number will not
272 /// fit in width, full number is still printed. Examples:
273 /// OS << format_hex(255, 4) => 0xff
274 /// OS << format_hex(255, 4, true) => 0xFF
275 /// OS << format_hex(255, 6) => 0x00ff
276 /// OS << format_hex(255, 2) => 0xff
277 inline FormattedNumber format_hex(uint64_t N, unsigned Width,
278 bool Upper = false) {
279 assert(Width <= 18 && "hex width must be <= 18");
280 return FormattedNumber(N, 0, Width, true, Upper, true);
283 /// format_hex_no_prefix - Output \p N as a fixed width hexadecimal. Does not
284 /// prepend '0x' to the outputted string. If number will not fit in width,
285 /// full number is still printed. Examples:
286 /// OS << format_hex_no_prefix(255, 4) => ff
287 /// OS << format_hex_no_prefix(255, 4, true) => FF
288 /// OS << format_hex_no_prefix(255, 6) => 00ff
289 /// OS << format_hex_no_prefix(255, 2) => ff
290 inline FormattedNumber format_hex_no_prefix(uint64_t N, unsigned Width,
291 bool Upper = false) {
292 assert(Width <= 18 && "hex width must be <= 18");
293 return FormattedNumber(N, 0, Width, true, Upper, false);
296 /// format_decimal - Output \p N as a right justified, fixed-width decimal. If
297 /// number will not fit in width, full number is still printed. Examples:
298 /// OS << format_decimal(0, 5) => " 0"
299 /// OS << format_decimal(255, 5) => " 255"
300 /// OS << format_decimal(-1, 3) => " -1"
301 /// OS << format_decimal(12345, 3) => "12345"
302 inline FormattedNumber format_decimal(int64_t N, unsigned Width) {
303 return FormattedNumber(0, N, Width, false, false, false);
307 } // end namespace llvm