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
29 // FIXME: This define is wrong:
30 // - _snprintf does not guarantee that trailing null is always added - if
31 // there is no space for null, it does not report any error.
32 // - According to C++ standard, snprintf should be visible in the 'std'
33 // namespace - this define makes this impossible.
34 #define snprintf _snprintf
39 /// This is a helper class used for handling formatted output. It is the
40 /// abstract base class of a templated derived class.
41 class format_object_base {
44 ~format_object_base() {} // Disallow polymorphic deletion.
45 virtual void home(); // Out of line virtual method.
47 /// Call snprintf() for this object, on the given buffer and size.
48 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0;
51 format_object_base(const char *fmt) : Fmt(fmt) {}
53 /// Format the object into the specified buffer. On success, this returns
54 /// the length of the formatted string. If the buffer is too small, this
55 /// returns a length to retry with, which will be larger than BufferSize.
56 unsigned print(char *Buffer, unsigned BufferSize) const {
57 assert(BufferSize && "Invalid buffer size!");
59 // Print the string, leaving room for the terminating null.
60 int N = snprint(Buffer, BufferSize);
62 // VC++ and old GlibC return negative on overflow, just double the size.
64 return BufferSize * 2;
66 // Other implementations yield number of bytes needed, not including the
68 if (unsigned(N) >= BufferSize)
71 // Otherwise N is the length of output (not including the final '\0').
76 /// These are templated helper classes used by the format function that
77 /// capture the object to be formated and the format string. When actually
78 /// printed, this synthesizes the string into a temporary buffer provided and
79 /// returns whether or not it is big enough.
82 class format_object1 final : public format_object_base {
85 format_object1(const char *fmt, const T &val)
86 : format_object_base(fmt), Val(val) {
89 int snprint(char *Buffer, unsigned BufferSize) const override {
90 return snprintf(Buffer, BufferSize, Fmt, Val);
94 template <typename T1, typename T2>
95 class format_object2 final : public format_object_base {
99 format_object2(const char *fmt, const T1 &val1, const T2 &val2)
100 : format_object_base(fmt), Val1(val1), Val2(val2) {
103 int snprint(char *Buffer, unsigned BufferSize) const override {
104 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2);
108 template <typename T1, typename T2, typename T3>
109 class format_object3 final : public format_object_base {
114 format_object3(const char *fmt, const T1 &val1, const T2 &val2,const T3 &val3)
115 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3) {
118 int snprint(char *Buffer, unsigned BufferSize) const override {
119 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3);
123 template <typename T1, typename T2, typename T3, typename T4>
124 class format_object4 final : public format_object_base {
130 format_object4(const char *fmt, const T1 &val1, const T2 &val2,
131 const T3 &val3, const T4 &val4)
132 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4) {
135 int snprint(char *Buffer, unsigned BufferSize) const override {
136 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4);
140 template <typename T1, typename T2, typename T3, typename T4, typename T5>
141 class format_object5 final : public format_object_base {
148 format_object5(const char *fmt, const T1 &val1, const T2 &val2,
149 const T3 &val3, const T4 &val4, const T5 &val5)
150 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4),
154 int snprint(char *Buffer, unsigned BufferSize) const override {
155 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5);
159 template <typename T1, typename T2, typename T3, typename T4, typename T5,
161 class format_object6 final : public format_object_base {
169 format_object6(const char *Fmt, const T1 &Val1, const T2 &Val2,
170 const T3 &Val3, const T4 &Val4, const T5 &Val5, const T6 &Val6)
171 : format_object_base(Fmt), Val1(Val1), Val2(Val2), Val3(Val3), Val4(Val4),
172 Val5(Val5), Val6(Val6) { }
174 int snprint(char *Buffer, unsigned BufferSize) const override {
175 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5, Val6);
179 /// These are helper functions used to produce formatted output. They use
180 /// template type deduction to construct the appropriate instance of the
181 /// format_object class to simplify their construction.
183 /// This is typically used like:
185 /// OS << format("%0.4f", myfloat) << '\n';
188 template <typename T>
189 inline format_object1<T> format(const char *Fmt, const T &Val) {
190 return format_object1<T>(Fmt, Val);
193 template <typename T1, typename T2>
194 inline format_object2<T1, T2> format(const char *Fmt, const T1 &Val1,
196 return format_object2<T1, T2>(Fmt, Val1, Val2);
199 template <typename T1, typename T2, typename T3>
200 inline format_object3<T1, T2, T3> format(const char *Fmt, const T1 &Val1,
201 const T2 &Val2, const T3 &Val3) {
202 return format_object3<T1, T2, T3>(Fmt, Val1, Val2, Val3);
205 template <typename T1, typename T2, typename T3, typename T4>
206 inline format_object4<T1, T2, T3, T4> format(const char *Fmt, const T1 &Val1,
207 const T2 &Val2, const T3 &Val3,
209 return format_object4<T1, T2, T3, T4>(Fmt, Val1, Val2, Val3, Val4);
212 template <typename T1, typename T2, typename T3, typename T4, typename T5>
213 inline format_object5<T1, T2, T3, T4, T5> format(const char *Fmt,const T1 &Val1,
214 const T2 &Val2, const T3 &Val3,
215 const T4 &Val4, const T5 &Val5) {
216 return format_object5<T1, T2, T3, T4, T5>(Fmt, Val1, Val2, Val3, Val4, Val5);
219 template <typename T1, typename T2, typename T3, typename T4, typename T5,
221 inline format_object6<T1, T2, T3, T4, T5, T6>
222 format(const char *Fmt, const T1 &Val1, const T2 &Val2, const T3 &Val3,
223 const T4 &Val4, const T5 &Val5, const T6 &Val6) {
224 return format_object6<T1, T2, T3, T4, T5, T6>(Fmt, Val1, Val2, Val3, Val4,
228 } // end namespace llvm