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  1. #include <streambuf>
  2. #include <ostream>
  3. #include <iostream>
  4.  
  5. //#define DEBUG
  6.  
  7. class MyData
  8. {
  9. 	//example data class, not used
  10. };
  11.  
  12. class MyBuffer : public std::basic_streambuf<char, std::char_traits<char> >
  13. {
  14.  
  15. public:
  16.  
  17. 	inline MyBuffer(MyData data) :
  18. 	data(data)
  19. 	{
  20. 		setp(buf, buf + BUF_SIZE);
  21. 	}
  22.  
  23. protected:
  24.  
  25. 	// This is called when buffer becomes full. If
  26. 	// buffer is not used, then this is called every
  27. 	// time when characters are put to stream.
  28. 	inline virtual int overflow(int c = Traits::eof())
  29. 	{
  30. #ifdef DEBUG
  31. 		std::cout << "(over)";
  32. #endif
  33. 		// Handle output
  34. 		putChars(pbase(), pptr());
  35. 		if (c != Traits::eof()) {
  36. 			char c2 = c;
  37. 			// Handle the one character that didn't fit to buffer
  38. 			putChars(&c2, &c2 + 1);
  39. 		}
  40. 		// This tells that buffer is empty again
  41. 		setp(buf, buf + BUF_SIZE);
  42.  
  43. 		return c;
  44. 	}
  45.  
  46. 	// This function is called when stream is flushed,
  47. 	// for example when std::endl is put to stream.
  48. 	inline virtual int sync(void)
  49. 	{
  50. 		// Handle output
  51. 		putChars(pbase(), pptr());
  52. 		// This tells that buffer is empty again
  53. 		setp(buf, buf + BUF_SIZE);
  54. 		return 0;
  55. 	}
  56.  
  57. private:
  58.  
  59. 	// For EOF detection
  60. 	typedef std::char_traits<char> Traits;
  61.  
  62. 	// Work in buffer mode. It is also possible to work without buffer.
  63. 	static const size_t BUF_SIZE = 64;
  64. 	char buf[BUF_SIZE];
  65.  
  66. 	// This is the example userdata
  67. 	MyData data;
  68.  
  69. 	// In this function, the characters are parsed.
  70. 	inline void putChars(const char* begin, const char* end){
  71. #ifdef DEBUG
  72. 		std::cout << "(putChars(" << static_cast<const void*>(begin) <<
  73. 		    "," << static_cast<const void*>(end) << "))";
  74. #endif
  75. 		//just print to stdout for now
  76. 		for (const char* c = begin; c < end; c++){
  77. 			std::cout << *c;
  78. 		}
  79. 	}
  80.  
  81. };
  82.  
  83. class MyOStream : public std::basic_ostream< char, std::char_traits< char > >
  84. {
  85.  
  86. public:
  87.  
  88. 	inline MyOStream(MyData data) :
  89. 	std::basic_ostream< char, std::char_traits< char > >(&buf),
  90. 	buf(data)
  91. 	{
  92. 	}
  93.  
  94. private:
  95.  
  96. 	MyBuffer buf;
  97.  
  98. };
  99.  
  100. int main(void)
  101. {
  102. 	MyData data;
  103. 	MyOStream o(data);
  104.  
  105. 	for (int i = 0; i < 8; i++)
  106. 		o << "hello world! ";
  107.  
  108. 	o << std::endl;
  109.  
  110. 	return 0;
  111. }
Success #stdin #stdout 0s 3416KB
comments (?)
stdin
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Standard input is empty
stdout
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hello world! hello world! hello world! hello world! hello world! hello world! hello world! hello world!
https://ideone.com/AFzNdO
language:
C++ (gcc 8.3)
created:
8 years ago
visibility:
public

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