From e487633bc664b9943c578539c068d558f507e901 Mon Sep 17 00:00:00 2001
From: wmayer <wmayer@users.sourceforge.net>
Date: Tue, 14 Jun 2016 13:59:02 +0200
Subject: [PATCH] + support of seek operation on PyStreambuf

---
 src/Base/Stream.cpp | 50 ++++++++++++++++++++++++++++++++++++++++++---
 src/Base/Stream.h   |  8 ++++++++
 2 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/src/Base/Stream.cpp b/src/Base/Stream.cpp
index f3583d03f..121fe507d 100644
--- a/src/Base/Stream.cpp
+++ b/src/Base/Stream.cpp
@@ -548,7 +548,7 @@ PyStreambuf::~PyStreambuf()
     Py_DECREF(inp);
 }
 
-std::streambuf::int_type PyStreambuf::underflow()
+PyStreambuf::int_type PyStreambuf::underflow()
 {
     if (gptr() < egptr()) {
         return traits_type::to_int_type(*gptr());
@@ -587,8 +587,8 @@ std::streambuf::int_type PyStreambuf::underflow()
     return traits_type::to_int_type(*gptr());
 }
 
-std::streambuf::int_type
-PyStreambuf::overflow(std::streambuf::int_type ch)
+PyStreambuf::int_type
+PyStreambuf::overflow(PyStreambuf::int_type ch)
 {
 #ifdef PYSTREAM_BUFFERED
     sync();
@@ -669,6 +669,50 @@ std::streamsize PyStreambuf::xsputn (const char* s, std::streamsize num)
 #endif
 }
 
+PyStreambuf::pos_type
+PyStreambuf::seekoff(PyStreambuf::off_type offset, PyStreambuf::seekdir dir, PyStreambuf::openmode /*mode*/)
+{
+    int whence = 0;
+    switch (dir) {
+    case std::ios_base::beg:
+        whence = 0;
+        break;
+    case std::ios_base::cur:
+        whence = 1;
+        break;
+    case std::ios_base::end:
+        whence = 2;
+        break;
+    default:
+        return pos_type(off_type(-1));
+    }
+
+    try {
+        Py::Tuple arg(2);
+        arg.setItem(0, Py::Long(static_cast<long>(offset)));
+        arg.setItem(1, Py::Long(whence));
+        Py::Callable seek(Py::Object(inp).getAttr("seek"));
+        seek.apply(arg);
+
+        // get current position
+        Py::Tuple arg2;
+        Py::Callable tell(Py::Object(inp).getAttr("tell"));
+        Py::Long pos(tell.apply(arg2));
+        long cur_pos = static_cast<long>(pos);
+        return static_cast<pos_type>(cur_pos);
+    }
+    catch(Py::Exception& e) {
+        e.clear();
+        return pos_type(off_type(-1));
+    }
+}
+
+PyStreambuf::pos_type
+PyStreambuf::seekpos(PyStreambuf::pos_type offset, PyStreambuf::openmode mode)
+{
+    return seekoff(offset, std::ios::beg, mode);
+}
+
 // ---------------------------------------------------------
 
 Streambuf::Streambuf(const std::string& data)
diff --git a/src/Base/Stream.h b/src/Base/Stream.h
index 0282a5557..4312f32e1 100644
--- a/src/Base/Stream.h
+++ b/src/Base/Stream.h
@@ -240,6 +240,12 @@ protected:
 
 class BaseExport PyStreambuf : public std::streambuf
 {
+    typedef std::streambuf::int_type int_type;
+    typedef std::streambuf::pos_type pos_type;
+    typedef std::streambuf::off_type off_type;
+    typedef std::ios::seekdir        seekdir;
+    typedef std::ios::openmode       openmode;
+
 public:
     PyStreambuf(PyObject* o, std::size_t buf_size = 256, std::size_t put_back = 8);
     virtual ~PyStreambuf();
@@ -249,6 +255,8 @@ protected:
     int_type overflow(int_type c = EOF);
     std::streamsize xsputn (const char* s, std::streamsize num);
     int sync();
+    pos_type seekoff(off_type offset, seekdir dir, openmode);
+    pos_type seekpos(pos_type offset, openmode mode);
 
 private:
     bool flushBuffer();