printf.h 3.2 KB
Newer Older
1
//  Copyright (c) 2018 PaddlePaddle Authors. All Rights Reserved.
D
dzhwinter 已提交
2 3 4 5 6 7 8 9 10 11 12 13
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
Y
Yi Wang 已提交
14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73

// Compared with std::stringstream, there are primary purpose of
// string::Printf:
//
// 1. Type-safe printing, with why and how explained in
//    http://www.drdobbs.com/stringprintf-a-typesafe-printf-family-fo/184401999.
//    Implementation includes
//
//    https://github.com/c42f/tinyformat
//    boost::format
//    std::stringstream
//
//    std::stringstream is not convenient enough in many cases.  For example:
//
//      std::cout << std::setprecision(2) << std::fixed << 1.23456 << "\n";
//
//    boost::format is the most convenient one.  We can have
//
//      std::cout << format("%2% %1%") % 36 % 77;
//
//    or
//
//      format fmter("%2% %1%");
//      fmter % 36; fmter % 77;
//      std::cout << fmter.c_str();
//
//    But the overloading of % might be overkilling and it would be
//    more efficient if it can write to std::cout directly.
//
//    tinyformat has an interface compatible with the C-printf style,
//    and it can writes to a stream or returns a std::string:
//
//      std::cout << tfm::printf(
//                  "%s, %s %d, %.2d:%.2d\n",
//                  weekday, month, day, hour, min);
//
//    or
//
//      tfm::format(std::cout,
//                  "%s, %s %d, %.2d:%.2d\n",
//                  weekday, month, day, hour, min);
//
// 2. High-performance -- most printed strings are not too long and
//    doens't need dynamic memory allocation.  Many StringPrintf
//    implementations doesn't enforce type-safe, but are
//    high-performance, including
//
//    https://developers.google.com/optimization/reference/base/stringprintf/
//    https://github.com/adobe/chromium/blob/master/base/stringprintf.h
//    https://github.com/google/protobuf/blob/master/src/google/protobuf/stubs/stringprintf.h
//
// According to
// https://github.com/c42f/tinyformat#compile-time-and-code-bloat,
// boost::format runs too slow and results in large executable binary
// files.  So here we port tinyformat.

#pragma once

#include <iostream>
#include <sstream>
74 75
#include <string>

76
#include "tinyformat/tinyformat.h"  // https://github.com/c42f/tinyformat
Y
Yi Wang 已提交
77 78 79 80 81 82

namespace paddle {
namespace string {

template <typename... Args>
void Fprintf(std::ostream& out, const char* fmt, const Args&... args) {
83
  tinyformat::vformat(out, fmt, tinyformat::makeFormatList(args...));
Y
Yi Wang 已提交
84 85 86
}

template <typename... Args>
M
minqiyang 已提交
87
std::string Sprintf(const char* fmt, const Args&... args) {
Y
Yi Wang 已提交
88
  std::ostringstream oss;
89
  Fprintf(oss, fmt, args...);
Y
Yi Wang 已提交
90 91 92 93
  return oss.str();
}

template <typename... Args>
94 95
void Printf(const char* fmt, const Args&... args) {
  Fprintf(std::cout, fmt, args...);
Y
Yi Wang 已提交
96 97 98 99
}

}  // namespace string
}  // namespace paddle