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iotest.cpp streambuf_iterator simple implementation
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#include <fstream> | |
#include <iostream> | |
#include <string> | |
#define USE_MY_LIB_ | |
#ifdef USE_MY_LIB_ | |
// 偽物ライブラリ | |
namespace MyLib | |
{ | |
template | |
< | |
class charT = char, | |
class traits = std::char_traits<charT> | |
> | |
class istreambuf_iterator | |
: public std::iterator | |
< | |
std::input_iterator_tag, | |
charT, | |
typename traits::off_type, | |
charT*, | |
charT& | |
> | |
{ | |
public: | |
typedef charT char_type; | |
typedef traits traits_type; | |
typedef typename traits::int_type int_type; | |
typedef std::basic_streambuf<charT, traits> streambuf_type; | |
typedef std::basic_istream<charT, traits> istream_type; | |
private: | |
streambuf_type *sbuf_; | |
int_type c_; | |
public: | |
// ctor | |
istreambuf_iterator() | |
: sbuf_(0), c_(traits::eof()) { } | |
istreambuf_iterator(istream_type& s) | |
// rdbuf() 格納されているストリームバッファのポインタを返す | |
: sbuf_(s.rdbuf()), c_(traits::eof()) { } | |
istreambuf_iterator(streambuf_type *s) | |
: sbuf_(s), c_(traits::eof()) { } | |
charT operator*() const | |
{ | |
// sgetc() ストリームから1文字読込む | |
return sbuf_->sgetc(); | |
} | |
istreambuf_iterator<charT, traits>& operator++() | |
{ | |
// sbumpc() ストリームから 1 文字を読み取り、読み取り位置を進める | |
sbuf_->sbumpc(); | |
return *this; | |
} | |
// istreambuf_iteratorの場合、初期構築時の状態か終端なのかだけを判断すればいい | |
// see: https://ja.cppreference.com/w/cpp/iterator/istreambuf_iterator/equal | |
bool equal(const istreambuf_iterator& b) const | |
{ | |
if ((sbuf_ == 0 || *(*this) == traits::eof()) && (b.sbuf_ == 0 || *b == traits::eof())) { | |
return true; | |
} | |
return false; | |
} | |
}; | |
template<class charT, class traits> | |
bool operator==(const istreambuf_iterator<charT, traits>& lhs, | |
const istreambuf_iterator<charT, traits>& rhs) | |
{ | |
return lhs.equal(rhs); | |
} | |
template<class charT, class traits> | |
bool operator!=(const istreambuf_iterator<charT, traits>& lhs, | |
const istreambuf_iterator<charT, traits>& rhs) | |
{ | |
return !lhs.equal(rhs); | |
} | |
} | |
#endif | |
int main() | |
{ | |
#ifdef USE_MY_LIB_ | |
// 偽物ライブラリ使います | |
std::cout << "USE DUMMY LIB!" << std::endl; | |
#else | |
// 本物ライブラリ使います | |
std::cout << "USE GENUINE LIB!" << std::endl; | |
#endif | |
// 標準ライブラリでファイルオープン | |
std::ifstream ifs("test.txt", std::ifstream::binary); | |
if (ifs.fail()) | |
{ | |
std::cerr << "failed." << std::endl; | |
return 1; | |
} | |
#ifdef USE_MY_LIB_ | |
MyLib::istreambuf_iterator<char> start_of_stream(ifs); | |
MyLib::istreambuf_iterator<char> end_of_stream; | |
#else | |
std::istreambuf_iterator<char> start_of_stream(ifs); | |
std::istreambuf_iterator<char> end_of_stream; | |
#endif | |
// 変数にファイル丸読み | |
std::string str(start_of_stream, end_of_stream); | |
// 結果表示 | |
std::cout << "[" << str << "]" << std::endl; | |
return 0; | |
} |
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