python support

packages/python/python.c

@@ -1,5 +1,7 @@
 
 #include "python.h"
+#include <YapStreams.h>
+#include <VFS.h>
 
 atom_t ATOM_true, ATOM_false, ATOM_colon, ATOM_dot, ATOM_none, ATOM_t,
   ATOM_comma, ATOM_builtin, ATOM_A, ATOM_V, ATOM_self, ATOM_nil, ATOM_brackets, ATOM_curly_brackets;
@@ -19,6 +21,88 @@ X_API PyObject *py_Sys;
 PyObject *py_Context;
 PyObject *py_ModDict;
 
+VFS_t pystream;
+
+static void *
+py_open( const char *name, const char *io_mode) {
+  if (strcasestr(name,"//python/")== name)
+    name += strlen("//python/");
+  // we assume object is already open, so there is no need to open it.
+  PyObject *stream = string_to_python( name, true, NULL);
+  if (stream == Py_None)
+    return NULL;
+  return stream;
+}
+		
+static bool
+py_close(int sno) {
+  PyObject *s = YAP_foreign_stream(sno);
+  PyObject* fclose = PyObject_GetAttrString(s, "close");
+  PyObject* rc= PyObject_CallObject(fclose, NULL);
+  bool v = (rc == Py_True);
+  return v;
+}
+
+static PyObject *  pyw; // buffer
+static int pyw_kind;
+PyObject *  pyw_data;
+
+static int
+py_put(int sno, int ch) {
+  PyObject *s = YAP_foreign_stream(sno);
+  PyUnicode_WRITE( pyw_kind, pyw_data, 0, ch );
+  PyObject* fput = PyObject_GetAttrString(s, "write");
+  PyObject_CallFunctionObjArgs(fput, pyw, NULL);
+  return ch;
+}
+
+static int
+py_get(int sno) {
+  PyObject *s = YAP_foreign_stream(sno);
+  PyObject* fget = PyObject_GetAttrString(s, "read");
+  PyObject *pyr = PyObject_CallFunctionObjArgs(fget, PyLong_FromLong(1), NULL);
+  return  PyUnicode_READ_CHAR( pyr, 0) ;
+}
+
+static int64_t  py_seek(int sno, int64_t where, int how) {
+  PyObject *s = YAP_foreign_stream(sno);
+  PyObject* fseek = PyObject_GetAttrString(s, "seek");
+  PyObject *pyr = PyObject_CallFunctionObjArgs(fseek, PyLong_FromLong(where), PyLong_FromLong(how), NULL);
+  return PyLong_AsLong(pyr);
+}
+
+static void
+py_flush(int sno) {
+  PyObject *s = YAP_foreign_stream(sno);
+  PyObject* flush = PyObject_GetAttrString(s, "flush");
+  PyObject_CallFunction( flush, NULL);
+}
+
+
+		
+static bool
+init_python_stream(void)
+{
+  pyw = PyUnicode_FromString("x");
+  pyw_kind = PyUnicode_KIND(pyw);
+  pyw_data = PyUnicode_DATA(pyw);
+  
+  pystream.name = "python stream";
+  pystream.vflags = VFS_CAN_WRITE|VFS_CAN_EXEC| VFS_CAN_SEEK|VFS_HAS_PREFIX;
+  pystream.prefix = "//python/";
+  pystream.suffix = NULL;
+  pystream.open = py_open;
+  pystream.close = py_close;
+  pystream.get_char = py_get;
+  pystream.put_char = py_put;
+  pystream.flush = py_flush;
+  pystream.seek = py_seek;
+  pystream.next = GLOBAL_VFS;
+  GLOBAL_VFS = &pystream;
+  // NULL;
+  return true;
+}
+
 X_API PyObject *py_F2P;
 
 bool python_in_python;
@@ -38,8 +122,10 @@ static void add_modules(void) {
     Py_INCREF(py_Yapex);
   //py_F2P = PyObject_GetAttrString(py_Yap, "globals");
   py_F2P = NULL;
+  init_python_stream();
 }
 
+
 static void install_py_constants(void) {
   FUNCTOR_dot2 = PL_new_functor(PL_new_atom("."), 2);
   // FUNCTOR_equal2 = PL_new_functor(PL_new_atom("="), 2);