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/// format_object_base - This is a helper class used for handling formatted
40/// output.  It is the 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  /// snprint - 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  /// print - Format the object into the specified buffer.  On success, this
54  /// returns the length of the formatted string.  If the buffer is too small,
55  /// this 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 impls yield number of bytes needed, not including the final '\0'.
67    if (unsigned(N) >= BufferSize)
68      return N+1;
69
70    // Otherwise N is the length of output (not including the final '\0').
71    return N;
72  }
73};
74
75/// format_object1 - This is a templated helper class used by the format
76/// function that captures the object to be formated and the format string. When
77/// actually printed, this synthesizes the string into a temporary buffer
78/// provided and returns whether or not it is big enough.
79template <typename T>
80class format_object1 : public format_object_base {
81  T Val;
82public:
83  format_object1(const char *fmt, const T &val)
84    : format_object_base(fmt), Val(val) {
85  }
86
87  virtual int snprint(char *Buffer, unsigned BufferSize) const {
88    return snprintf(Buffer, BufferSize, Fmt, Val);
89  }
90};
91
92/// format_object2 - This is a templated helper class used by the format
93/// function that captures the object to be formated and the format string. When
94/// actually printed, this synthesizes the string into a temporary buffer
95/// provided and returns whether or not it is big enough.
96template <typename T1, typename T2>
97class format_object2 : public format_object_base {
98  T1 Val1;
99  T2 Val2;
100public:
101  format_object2(const char *fmt, const T1 &val1, const T2 &val2)
102  : format_object_base(fmt), Val1(val1), Val2(val2) {
103  }
104
105  virtual int snprint(char *Buffer, unsigned BufferSize) const {
106    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2);
107  }
108};
109
110/// format_object3 - This is a templated helper class used by the format
111/// function that captures the object to be formated and the format string. When
112/// actually printed, this synthesizes the string into a temporary buffer
113/// provided and returns whether or not it is big enough.
114template <typename T1, typename T2, typename T3>
115class format_object3 : public format_object_base {
116  T1 Val1;
117  T2 Val2;
118  T3 Val3;
119public:
120  format_object3(const char *fmt, const T1 &val1, const T2 &val2,const T3 &val3)
121    : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3) {
122  }
123
124  virtual int snprint(char *Buffer, unsigned BufferSize) const {
125    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3);
126  }
127};
128
129/// format_object4 - This is a templated helper class used by the format
130/// function that captures the object to be formated and the format string. When
131/// actually printed, this synthesizes the string into a temporary buffer
132/// provided and returns whether or not it is big enough.
133template <typename T1, typename T2, typename T3, typename T4>
134class format_object4 : public format_object_base {
135  T1 Val1;
136  T2 Val2;
137  T3 Val3;
138  T4 Val4;
139public:
140  format_object4(const char *fmt, const T1 &val1, const T2 &val2,
141                 const T3 &val3, const T4 &val4)
142    : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4) {
143  }
144
145  virtual int snprint(char *Buffer, unsigned BufferSize) const {
146    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4);
147  }
148};
149
150/// format_object5 - This is a templated helper class used by the format
151/// function that captures the object to be formated and the format string. When
152/// actually printed, this synthesizes the string into a temporary buffer
153/// provided and returns whether or not it is big enough.
154template <typename T1, typename T2, typename T3, typename T4, typename T5>
155class format_object5 : public format_object_base {
156  T1 Val1;
157  T2 Val2;
158  T3 Val3;
159  T4 Val4;
160  T5 Val5;
161public:
162  format_object5(const char *fmt, const T1 &val1, const T2 &val2,
163                 const T3 &val3, const T4 &val4, const T5 &val5)
164    : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3), Val4(val4),
165      Val5(val5) {
166  }
167
168  virtual int snprint(char *Buffer, unsigned BufferSize) const {
169    return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3, Val4, Val5);
170  }
171};
172
173/// This is a helper function that is used to produce formatted output.
174///
175/// This is typically used like:
176/// \code
177///   OS << format("%0.4f", myfloat) << '\n';
178/// \endcode
179template <typename T>
180inline format_object1<T> format(const char *Fmt, const T &Val) {
181  return format_object1<T>(Fmt, Val);
182}
183
184/// This is a helper function that is used to produce formatted output.
185///
186/// This is typically used like:
187/// \code
188///   OS << format("%0.4f", myfloat) << '\n';
189/// \endcode
190template <typename T1, typename T2>
191inline format_object2<T1, T2> format(const char *Fmt, const T1 &Val1,
192                                     const T2 &Val2) {
193  return format_object2<T1, T2>(Fmt, Val1, Val2);
194}
195
196/// This is a helper function that is used to produce formatted output.
197///
198/// This is typically used like:
199/// \code
200///   OS << format("%0.4f", myfloat) << '\n';
201/// \endcode
202template <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);
206}
207
208/// This is a helper function that is used to produce formatted output.
209///
210/// This is typically used like:
211/// \code
212///   OS << format("%0.4f", myfloat) << '\n';
213/// \endcode
214template <typename T1, typename T2, typename T3, typename T4>
215inline format_object4<T1, T2, T3, T4> format(const char *Fmt, const T1 &Val1,
216                                             const T2 &Val2, const T3 &Val3,
217                                             const T4 &Val4) {
218  return format_object4<T1, T2, T3, T4>(Fmt, Val1, Val2, Val3, Val4);
219}
220
221/// This is a helper function that is used to produce formatted output.
222///
223/// This is typically used like:
224/// \code
225///   OS << format("%0.4f", myfloat) << '\n';
226/// \endcode
227template <typename T1, typename T2, typename T3, typename T4, typename T5>
228inline format_object5<T1, T2, T3, T4, T5> format(const char *Fmt,const T1 &Val1,
229                                             const T2 &Val2, const T3 &Val3,
230                                             const T4 &Val4, const T5 &Val5) {
231  return format_object5<T1, T2, T3, T4, T5>(Fmt, Val1, Val2, Val3, Val4, Val5);
232}
233
234} // end namespace llvm
235
236#endif
237