1 files changed, 142 insertions, 0 deletions
diff --git a/pyfstream.h b/pyfstream.h
new file mode 100644
index 00000000..e10b5bd5
--- /dev/null
+++ b/pyfstream.h
@@ -0,0 +1,142 @@
+#ifndef _PYFSTREAM_H
+#define _PYFSTREAM_H
+
+#include <istream>
+#include <ostream>
+#include <streambuf>
+#include <cstdio>
+#include <cstring>
+
+#include "Python.h"
+
+// pyofstream
+// - a stream that writes on a Python file object
+
+class pyoutbuf : public std::streambuf {
+ protected:
+  PyFileObject * fo;    // Python file object
+ public:
+  // constructor
+  pyoutbuf (PyFileObject * _fo) : fo(_fo) {}
+
+ protected:
+  // write one character
+  virtual int_type overflow (int_type c) {
+    if (c != EOF) {
+      char z[2];
+      z[0] = c;
+      z[1] = '\0';
+      if (PyFile_WriteString(z, (PyObject *)fo) < 0) {
+	return EOF;
+      }
+    }
+    return c;
+  }
+
+  // write multiple characters
+  virtual std::streamsize xsputn (const char* s, std::streamsize num) {
+    if (PyFile_WriteString(s, (PyObject *)fo) < 0)
+      return 0;
+    return num;
+  }
+};
+
+class pyofstream : public std::ostream {
+ protected:
+  pyoutbuf buf;
+ public:
+  pyofstream (PyFileObject * fo) : std::ostream(0), buf(fo) {
+    rdbuf(&buf);
+  }
+};
+
+// pyifstream
+// - a stream that reads on a file descriptor
+
+class pyinbuf : public std::streambuf {
+ protected:
+  PyFileObject * fo;    // Python file object
+ protected:
+  /* data buffer:
+   * - at most, pbSize characters in putback area plus
+   * - at most, bufSize characters in ordinary read buffer
+   */
+  static const int pbSize  = 4;	   // size of putback area
+  static const int bufSize = 1024; // size of the data buffer
+  char buffer[bufSize + pbSize];   // data buffer
+
+ public:
+  /* constructor
+   * - initialize file descriptor
+   * - initialize empty data buffer
+   * - no putback area
+   * => force underflow()
+   */
+  pyinbuf (PyFileObject * _fo) : fo(_fo) {
+    setg (buffer+pbSize,     // beginning of putback area
+	  buffer+pbSize,     // read position
+	  buffer+pbSize);    // end position
+  }
+
+ protected:
+  // insert new characters into the buffer
+  virtual int_type underflow () {
+#ifndef _MSC_VER
+    using std::memmove;
+#endif
+
+    // is read position before end of buffer?
+    if (gptr() < egptr()) {
+      return traits_type::to_int_type(*gptr());
+    }
+
+    /* process size of putback area
+     * - use number of characters read
+     * - but at most size of putback area
+     */
+    int numPutback;
+    numPutback = gptr() - eback();
+    if (numPutback > pbSize) {
+      numPutback = pbSize;
+    }
+
+    /* copy up to pbSize characters previously read into
+     * the putback area
+     */
+    memmove (buffer+(pbSize-numPutback), gptr()-numPutback,
+	     numPutback);
+
+    // read at most bufSize new characters
+    int num;
+    PyObject *line = PyFile_GetLine((PyObject *)fo, bufSize);
+    if (! line || ! PyString_Check(line)) {
+      // ERROR or EOF
+      return EOF;
+    }
+
+    num = PyString_Size(line);
+    if (num == 0)
+      return EOF;
+
+    memmove (buffer+pbSize, PyString_AsString(line), num);
+
+    // reset buffer pointers
+    setg (buffer+(pbSize-numPutback),   // beginning of putback area
+	  buffer+pbSize,                // read position
+	  buffer+pbSize+num);           // end of buffer
+
+    // return next character
+    return traits_type::to_int_type(*gptr());
+  }
+};
+
+class pyifstream : public std::istream {
+ protected:
+  pyinbuf buf;
+ public:
+  pyifstream (PyFileObject * fo) : std::istream(0), buf(fo) {
+    rdbuf(&buf);
+  }
+};
+
+#endif // _PYFSTREAM_H