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"
32 // FIXME: This define is wrong:
33 // - _snprintf does not guarantee that trailing null is always added - if
34 // there is no space for null, it does not report any error.
35 // - According to C++ standard, snprintf should be visible in the 'std'
36 // namespace - this define makes this impossible.
37 #define snprintf _snprintf
42 /// This is a helper class used for handling formatted output. It is the
43 /// abstract base class of a templated derived class.
44 class format_object_base {
47 ~format_object_base() {} // Disallow polymorphic deletion.
48 virtual void home(); // Out of line virtual method.
50 /// Call snprintf() for this object, on the given buffer and size.
51 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0;
54 format_object_base(const char *fmt) : Fmt(fmt) {}
56 /// Format the object into the specified buffer. On success, this returns
57 /// the length of the formatted string. If the buffer is too small, this
58 /// returns a length to retry with, which will be larger than BufferSize.
59 unsigned print(char *Buffer, unsigned BufferSize) const {
60 assert(BufferSize && "Invalid buffer size!");
62 // Print the string, leaving room for the terminating null.
63 int N = snprint(Buffer, BufferSize);
65 // VC++ and old GlibC return negative on overflow, just double the size.
67 return BufferSize * 2;
69 // Other implementations yield number of bytes needed, not including the
71 if (unsigned(N) >= BufferSize)
74 // Otherwise N is the length of output (not including the final '\0').
79 /// These are templated helper classes used by the format function that
80 /// capture the object to be formated and the format string. When actually
81 /// printed, this synthesizes the string into a temporary buffer provided and
82 /// returns whether or not it is big enough.
85 class format_object1 final : public format_object_base {
88 format_object1(const char *fmt, const T &val)
89 : format_object_base(fmt), Val(val) {
92 int snprint(char *Buffer, unsigned BufferSize) const override {
93 return snprintf(Buffer, BufferSize, Fmt, Val);
97 template <typename T1, typename T2>
98 class format_object2 final : public format_object_base {
102 format_object2(const char *fmt, const T1 &val1, const T2 &val2)
103 : format_object_base(fmt), Val1(val1), Val2(val2) {
106 int snprint(char *Buffer, unsigned BufferSize) const override {
107 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2);
111 template <typename T1, typename T2, typename T3>
112 class format_object3 final : public format_object_base {
117 format_object3(const char *fmt, const T1 &val1, const T2 &val2,const T3 &val3)
118 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3) {
121 int snprint(char *Buffer, unsigned BufferSize) const override {
122 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3);
126 template <typename T1, typename T2, typename T3, typename T4>
127 class format_object4 final : public format_object_base {
133 format_object4(const char *fmt, const T1 &val1, const T2 &val2,
134 const T3 &val3, const T4 &val4)
135 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4) {
138 int snprint(char *Buffer, unsigned BufferSize) const override {
139 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4);
143 template <typename T1, typename T2, typename T3, typename T4, typename T5>
144 class format_object5 final : public format_object_base {
151 format_object5(const char *fmt, const T1 &val1, const T2 &val2,
152 const T3 &val3, const T4 &val4, const T5 &val5)
153 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4),
157 int snprint(char *Buffer, unsigned BufferSize) const override {
158 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5);
162 template <typename T1, typename T2, typename T3, typename T4, typename T5,
164 class format_object6 final : public format_object_base {
172 format_object6(const char *Fmt, const T1 &Val1, const T2 &Val2,
173 const T3 &Val3, const T4 &Val4, const T5 &Val5, const T6 &Val6)
174 : format_object_base(Fmt), Val1(Val1), Val2(Val2), Val3(Val3), Val4(Val4),
175 Val5(Val5), Val6(Val6) { }
177 int snprint(char *Buffer, unsigned BufferSize) const override {
178 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5, Val6);
182 /// These are helper functions used to produce formatted output. They use
183 /// template type deduction to construct the appropriate instance of the
184 /// format_object class to simplify their construction.
186 /// This is typically used like:
188 /// OS << format("%0.4f", myfloat) << '\n';
191 template <typename T>
192 inline format_object1<T> format(const char *Fmt, const T &Val) {
193 return format_object1<T>(Fmt, Val);
196 template <typename T1, typename T2>
197 inline format_object2<T1, T2> format(const char *Fmt, const T1 &Val1,
199 return format_object2<T1, T2>(Fmt, Val1, Val2);
202 template <typename T1, typename T2, typename T3>
203 inline format_object3<T1, T2, T3> format(const char *Fmt, const T1 &Val1,
204 const T2 &Val2, const T3 &Val3) {
205 return format_object3<T1, T2, T3>(Fmt, Val1, Val2, Val3);
208 template <typename T1, typename T2, typename T3, typename T4>
209 inline format_object4<T1, T2, T3, T4> format(const char *Fmt, const T1 &Val1,
210 const T2 &Val2, const T3 &Val3,
212 return format_object4<T1, T2, T3, T4>(Fmt, Val1, Val2, Val3, Val4);
215 template <typename T1, typename T2, typename T3, typename T4, typename T5>
216 inline format_object5<T1, T2, T3, T4, T5> format(const char *Fmt,const T1 &Val1,
217 const T2 &Val2, const T3 &Val3,
218 const T4 &Val4, const T5 &Val5) {
219 return format_object5<T1, T2, T3, T4, T5>(Fmt, Val1, Val2, Val3, Val4, Val5);
222 template <typename T1, typename T2, typename T3, typename T4, typename T5,
224 inline format_object6<T1, T2, T3, T4, T5, T6>
225 format(const char *Fmt, const T1 &Val1, const T2 &Val2, const T3 &Val3,
226 const T4 &Val4, const T5 &Val5, const T6 &Val6) {
227 return format_object6<T1, T2, T3, T4, T5, T6>(Fmt, Val1, Val2, Val3, Val4,
231 /// This is a helper class used for left_justify() and right_justify().
232 class FormattedString {
236 friend class raw_ostream;
238 FormattedString(StringRef S, unsigned W, bool R)
239 : Str(S), Width(W), RightJustify(R) { }
242 /// left_justify - append spaces after string so total output is
243 /// \p Width characters. If \p Str is larger that \p Width, full string
244 /// is written with no padding.
245 inline FormattedString left_justify(StringRef Str, unsigned Width) {
246 return FormattedString(Str, Width, false);
249 /// right_justify - add spaces before string so total output is
250 /// \p Width characters. If \p Str is larger that \p Width, full string
251 /// is written with no padding.
252 inline FormattedString right_justify(StringRef Str, unsigned Width) {
253 return FormattedString(Str, Width, true);
256 /// This is a helper class used for format_hex() and format_decimal().
257 class FormattedNumber {
263 friend class raw_ostream;
265 FormattedNumber(uint64_t HV, int64_t DV, unsigned W, bool H, bool U)
266 : HexValue(HV), DecValue(DV), Width(W), Hex(H), Upper(U) { }
269 /// format_hex - Output \p N as a fixed width hexadecimal. If number will not
270 /// fit in width, full number is still printed. Examples:
271 /// OS << format_hex(255, 4) => 0xff
272 /// OS << format_hex(255, 4, true) => 0xFF
273 /// OS << format_hex(255, 6) => 0x00ff
274 /// OS << format_hex(255, 2) => 0xff
275 inline FormattedNumber format_hex(uint64_t N, unsigned Width, bool Upper=false) {
276 assert(Width <= 18 && "hex width must be <= 18");
277 return FormattedNumber(N, 0, Width, true, Upper);
280 /// format_decimal - Output \p N as a right justified, fixed-width decimal. If
281 /// number will not fit in width, full number is still printed. Examples:
282 /// OS << format_decimal(0, 5) => " 0"
283 /// OS << format_decimal(255, 5) => " 255"
284 /// OS << format_decimal(-1, 3) => " -1"
285 /// OS << format_decimal(12345, 3) => "12345"
286 inline FormattedNumber format_decimal(int64_t N, unsigned Width) {
287 return FormattedNumber(0, N, Width, false, false);
291 } // end namespace llvm