1//===- Format.h - Efficient printf-style formatting for streams -*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
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
13// example):
14//
15//    OS << "mynumber: " << format("%4.5f", 1234.412) << '\n';
16//
17// Or if you prefer:
18//
19//  OS << format("mynumber: %4.5f\n", 1234.412);
20//
21//===----------------------------------------------------------------------===//
22
23#ifndef LLVM_SUPPORT_FORMAT_H
24#define LLVM_SUPPORT_FORMAT_H
25
26#include <cassert>
27#include <cstdio>
28#ifdef _MSC_VER
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
35#endif
36
37namespace llvm {
38
39/// This is a helper class used for handling formatted output.  It is the
40/// abstract base class of a templated derived class.
41class format_object_base {
42protected:
43  const char *Fmt;
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
49public:
50  format_object_base(const char *fmt) : Fmt(fmt) {}
51  virtual ~format_object_base() {}
52
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!");
58
59    // Print the string, leaving room for the terminating null.
60    int N = snprint(Buffer, BufferSize);
61
62    // VC++ and old GlibC return negative on overflow, just double the size.
63    if (N < 0)
64      return BufferSize * 2;
65
66    // Other implementations yield number of bytes needed, not including the
67    // final '\0'.
68    if (unsigned(N) >= BufferSize)
69      return N + 1;
70
71    // Otherwise N is the length of output (not including the final '\0').
72    return N;
73  }
74};
75
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.
80
81template <typename T>
82class format_object1 : public format_object_base {
83  T Val;
84public:
85  format_object1(const char *fmt, const T &val)
86    : format_object_base(fmt), Val(val) {
87  }
88
89  int snprint(char *Buffer, unsigned BufferSize) const override {
90    return snprintf(Buffer, BufferSize, Fmt, Val);
91  }
92};
93
94template <typename T1, typename T2>
95class format_object2 : public format_object_base {
96  T1 Val1;
97  T2 Val2;
98public:
99  format_object2(const char *fmt, const T1 &val1, const T2 &val2)
100  : format_object_base(fmt), Val1(val1), Val2(val2) {
101  }
102
103  int snprint(char *Buffer, unsigned BufferSize) const override {
104    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2);
105  }
106};
107
108template <typename T1, typename T2, typename T3>
109class format_object3 : public format_object_base {
110  T1 Val1;
111  T2 Val2;
112  T3 Val3;
113public:
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) {
116  }
117
118  int snprint(char *Buffer, unsigned BufferSize) const override {
119    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3);
120  }
121};
122
123template <typename T1, typename T2, typename T3, typename T4>
124class format_object4 : public format_object_base {
125  T1 Val1;
126  T2 Val2;
127  T3 Val3;
128  T4 Val4;
129public:
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) {
133  }
134
135  int snprint(char *Buffer, unsigned BufferSize) const override {
136    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4);
137  }
138};
139
140template <typename T1, typename T2, typename T3, typename T4, typename T5>
141class format_object5 : public format_object_base {
142  T1 Val1;
143  T2 Val2;
144  T3 Val3;
145  T4 Val4;
146  T5 Val5;
147public:
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),
151      Val5(val5) {
152  }
153
154  int snprint(char *Buffer, unsigned BufferSize) const override {
155    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5);
156  }
157};
158
159template <typename T1, typename T2, typename T3, typename T4, typename T5,
160          typename T6>
161class format_object6 : public format_object_base {
162  T1 Val1;
163  T2 Val2;
164  T3 Val3;
165  T4 Val4;
166  T5 Val5;
167  T6 Val6;
168public:
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) { }
173
174  int snprint(char *Buffer, unsigned BufferSize) const override {
175    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5, Val6);
176  }
177};
178
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.
182///
183/// This is typically used like:
184/// \code
185///   OS << format("%0.4f", myfloat) << '\n';
186/// \endcode
187
188template <typename T>
189inline format_object1<T> format(const char *Fmt, const T &Val) {
190  return format_object1<T>(Fmt, Val);
191}
192
193template <typename T1, typename T2>
194inline format_object2<T1, T2> format(const char *Fmt, const T1 &Val1,
195                                     const T2 &Val2) {
196  return format_object2<T1, T2>(Fmt, Val1, Val2);
197}
198
199template <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);
203}
204
205template <typename T1, typename T2, typename T3, typename T4>
206inline format_object4<T1, T2, T3, T4> format(const char *Fmt, const T1 &Val1,
207                                             const T2 &Val2, const T3 &Val3,
208                                             const T4 &Val4) {
209  return format_object4<T1, T2, T3, T4>(Fmt, Val1, Val2, Val3, Val4);
210}
211
212template <typename T1, typename T2, typename T3, typename T4, typename T5>
213inline 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);
217}
218
219template <typename T1, typename T2, typename T3, typename T4, typename T5,
220          typename T6>
221inline format_object6<T1, T2, T3, T4, T5, T6>
222format(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,
225                                                Val5, Val6);
226}
227
228} // end namespace llvm
229
230#endif
231