Add ReaderStreamBuf and WriterStreamBuf for std::istream and std::ostream interfaces.

coding/coding.pro

@@ -26,6 +26,7 @@ SOURCES += \
     reader.cpp \
     zip_reader.cpp \
     mmap_reader.cpp \
+    reader_streambuf.cpp \
 
 HEADERS += \
     internal/xmlparser.h \
@@ -79,3 +80,4 @@ HEADERS += \
     read_write_utils.hpp \
     file_reader_stream.hpp \
     file_writer_stream.hpp \
+    reader_streambuf.hpp \

coding/coding_tests/reader_test.cpp

@@ -6,6 +6,10 @@
 #include "../file_reader.hpp"
 #include "../file_writer.hpp"
 #include "../buffer_reader.hpp"
+#include "../reader_streambuf.hpp"
+
+#include "../../std/fstream.hpp"
+
 
 namespace
 {
@@ -97,3 +101,33 @@ UNIT_TEST(SharedMemReader)
   TEST_EQUAL(s1, "123", ());
   TEST_EQUAL(s2, "123", ());
 }
+
+UNIT_TEST(ReaderStreamBuf)
+{
+  string const name = "test.txt";
+
+  {
+    WriterStreamBuf buffer(new FileWriter(name));
+    ostream s(&buffer);
+    s << "hey!" << '\n' << 1 << '\n' << 3.14 << '\n' << 0x0102030405060708ull << std::endl;
+  }
+
+  {
+    ReaderStreamBuf buffer(new FileReader(name));
+    istream s(&buffer);
+
+    std::string str;
+    int i;
+    double d;
+    unsigned long long ull;
+
+    s >> str >> i >> d >> ull;
+
+    TEST_EQUAL(str, "hey!", ());
+    TEST_EQUAL(i, 1, ());
+    TEST_ALMOST_EQUAL(d, 3.14, ());
+    TEST_EQUAL(ull, 0x0102030405060708ull, ());
+  }
+
+  FileWriter::DeleteFileX(name);
+}

coding/reader_streambuf.cpp

@@ -0,0 +1,40 @@
+#include "reader_streambuf.hpp"
+#include "reader.hpp"
+
+#include "../std/algorithm.hpp"
+
+
+ReaderStreamBuf::ReaderStreamBuf(Reader * p)
+: m_p(p), m_pos(0), m_size(p->Size())
+{
+}
+
+ReaderStreamBuf::~ReaderStreamBuf()
+{
+  delete m_p;
+}
+
+std::streamsize ReaderStreamBuf::xsgetn(char_type * s, std::streamsize n)
+{
+  uint64_t const count = min(static_cast<uint64_t>(n), m_size - m_pos);
+  if (count > 0)
+  {
+    m_p->Read(m_pos, s, count);
+    m_pos += count;
+  }
+  return count;
+}
+
+ReaderStreamBuf::int_type ReaderStreamBuf::underflow()
+{
+  std::streamsize s = xsgetn(m_buf, sizeof(m_buf));
+  if (s > 0)
+  {
+    setg(m_buf, m_buf, m_buf + s);
+    return traits_type::to_int_type(m_buf[0]);
+  }
+  else
+  {
+    return traits_type::eof();
+  }
+}

coding/reader_streambuf.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include "../std/iostream.hpp"
+
+class Reader;
+
+class ReaderStreamBuf : public std::streambuf
+{
+  Reader * m_p;
+  uint64_t m_pos, m_size;
+
+public:
+  typedef std::streambuf::traits_type traits_type;
+  typedef std::streambuf::char_type char_type;
+  typedef std::streambuf::int_type int_type;
+
+  /// Takes the ownership of p. Reader should be allocated in dynamic memory.
+  ReaderStreamBuf(Reader * p);
+  virtual ~ReaderStreamBuf();
+
+private:
+  virtual std::streamsize xsgetn(char_type * s, std::streamsize n);
+  virtual int_type underflow();
+
+  char m_buf[1];
+};