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 #define snprintf _snprintf
34 /// format_object_base - This is a helper class used for handling formatted
35 /// output. It is the abstract base class of a templated derived class.
36 class format_object_base {
39 virtual void home(); // Out of line virtual method.
41 /// snprint - Call snprintf() for this object, on the given buffer and size.
42 virtual int snprint(char *Buffer, unsigned BufferSize) const = 0;
45 format_object_base(const char *fmt) : Fmt(fmt) {}
46 virtual ~format_object_base() {}
48 /// print - Format the object into the specified buffer. On success, this
49 /// returns the length of the formatted string. If the buffer is too small,
50 /// this returns a length to retry with, which will be larger than BufferSize.
51 unsigned print(char *Buffer, unsigned BufferSize) const {
52 assert(BufferSize && "Invalid buffer size!");
54 // Print the string, leaving room for the terminating null.
55 int N = snprint(Buffer, BufferSize);
57 // VC++ and old GlibC return negative on overflow, just double the size.
61 // Other impls yield number of bytes needed, not including the final '\0'.
62 if (unsigned(N) >= BufferSize)
65 // Otherwise N is the length of output (not including the final '\0').
70 /// format_object1 - This is a templated helper class used by the format
71 /// function that captures the object to be formated and the format string. When
72 /// actually printed, this synthesizes the string into a temporary buffer
73 /// provided and returns whether or not it is big enough.
75 class format_object1 : public format_object_base {
78 format_object1(const char *fmt, const T &val)
79 : format_object_base(fmt), Val(val) {
82 virtual int snprint(char *Buffer, unsigned BufferSize) const {
83 return snprintf(Buffer, BufferSize, Fmt, Val);
87 /// format_object2 - This is a templated helper class used by the format
88 /// function that captures the object to be formated and the format string. When
89 /// actually printed, this synthesizes the string into a temporary buffer
90 /// provided and returns whether or not it is big enough.
91 template <typename T1, typename T2>
92 class format_object2 : public format_object_base {
96 format_object2(const char *fmt, const T1 &val1, const T2 &val2)
97 : format_object_base(fmt), Val1(val1), Val2(val2) {
100 virtual int snprint(char *Buffer, unsigned BufferSize) const {
101 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2);
105 /// format_object3 - This is a templated helper class used by the format
106 /// function that captures the object to be formated and the format string. When
107 /// actually printed, this synthesizes the string into a temporary buffer
108 /// provided and returns whether or not it is big enough.
109 template <typename T1, typename T2, typename T3>
110 class format_object3 : public format_object_base {
115 format_object3(const char *fmt, const T1 &val1, const T2 &val2,const T3 &val3)
116 : format_object_base(fmt), Val1(val1), Val2(val2), Val3(val3) {
119 virtual int snprint(char *Buffer, unsigned BufferSize) const {
120 return snprintf(Buffer, BufferSize, Fmt, Val1, Val2, Val3);
124 /// format - This is a helper function that is used to produce formatted output.
125 /// This is typically used like: OS << format("%0.4f", myfloat) << '\n';
126 template <typename T>
127 inline format_object1<T> format(const char *Fmt, const T &Val) {
128 return format_object1<T>(Fmt, Val);
131 /// format - This is a helper function that is used to produce formatted output.
132 /// This is typically used like: OS << format("%0.4f", myfloat) << '\n';
133 template <typename T1, typename T2>
134 inline format_object2<T1, T2> format(const char *Fmt, const T1 &Val1,
136 return format_object2<T1, T2>(Fmt, Val1, Val2);
139 /// format - This is a helper function that is used to produce formatted output.
140 /// This is typically used like: OS << format("%0.4f", myfloat) << '\n';
141 template <typename T1, typename T2, typename T3>
142 inline format_object3<T1, T2, T3> format(const char *Fmt, const T1 &Val1,
143 const T2 &Val2, const T3 &Val3) {
144 return format_object3<T1, T2, T3>(Fmt, Val1, Val2, Val3);
147 } // end namespace llvm