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 /// 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.
41 class format_object_base {
44 virtual void home(); // Out of line virtual method.
46 /// snprint - Call snprintf() for this object, on the given buffer and size.
47 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0;
50 format_object_base(const char *fmt) : Fmt(fmt) {}
51 virtual ~format_object_base() {}
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!");
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.
66 // Other impls yield number of bytes needed, not including the final '\0'.
67 if (unsigned(N) >= BufferSize)
70 // Otherwise N is the length of output (not including the final '\0').
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.
80 class format_object1 : public format_object_base {
83 format_object1(const char *fmt, const T &val)
84 : format_object_base(fmt), Val(val) {
87 virtual int snprint(char *Buffer, unsigned BufferSize) const {
88 return snprintf(Buffer, BufferSize, Fmt, Val);
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.
96 template <typename T1, typename T2>
97 class format_object2 : 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 virtual int snprint(char *Buffer, unsigned BufferSize) const {
106 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2);
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.
114 template <typename T1, typename T2, typename T3>
115 class format_object3 : public format_object_base {
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) {
124 virtual int snprint(char *Buffer, unsigned BufferSize) const {
125 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3);
129 /// format - This is a helper function that is used to produce formatted output.
130 /// This is typically used like: OS << format("%0.4f", myfloat) << '\n';
131 template <typename T>
132 inline format_object1<T> format(const char *Fmt, const T &Val) {
133 return format_object1<T>(Fmt, Val);
136 /// format - This is a helper function that is used to produce formatted output.
137 /// This is typically used like: OS << format("%0.4f", myfloat) << '\n';
138 template <typename T1, typename T2>
139 inline format_object2<T1, T2> format(const char *Fmt, const T1 &Val1,
141 return format_object2<T1, T2>(Fmt, Val1, Val2);
144 /// format - This is a helper function that is used to produce formatted output.
145 /// This is typically used like: OS << format("%0.4f", myfloat) << '\n';
146 template <typename T1, typename T2, typename T3>
147 inline format_object3<T1, T2, T3> format(const char *Fmt, const T1 &Val1,
148 const T2 &Val2, const T3 &Val3) {
149 return format_object3<T1, T2, T3>(Fmt, Val1, Val2, Val3);
152 } // end namespace llvm