/* General utility routines for GDB/Python.

   Copyright (C) 2008, 2009, 2010 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "charset.h"
#include "python-internal.h"


/* This is a cleanup function which decrements the refcount on a
   Python object.  */

static void
py_decref (void *p)
{
  PyObject *py = p;

  /* Note that we need the extra braces in this 'if' to avoid a
     warning from gcc.  */
  if (py)
    {
      Py_DECREF (py);
    }
}

/* Return a new cleanup which will decrement the Python object's
   refcount when run.  */

struct cleanup *
make_cleanup_py_decref (PyObject *py)
{
  return make_cleanup (py_decref, (void *) py);
}

/* Converts a Python 8-bit string to a unicode string object.  Assumes the
   8-bit string is in the host charset.  If an error occurs during conversion,
   returns NULL with a python exception set.

   As an added bonus, the functions accepts a unicode string and returns it
   right away, so callers don't need to check which kind of string they've
   got.

   If the given object is not one of the mentioned string types, NULL is
   returned, with the TypeError python exception set.  */
PyObject *
python_string_to_unicode (PyObject *obj)
{
  PyObject *unicode_str;

  /* If obj is already a unicode string, just return it.
     I wish life was always that simple...  */
  if (PyUnicode_Check (obj))
    {
      unicode_str = obj;
      Py_INCREF (obj);
    }
  
  else if (PyString_Check (obj))
    unicode_str = PyUnicode_FromEncodedObject (obj, host_charset (), NULL);
  else
    {
      PyErr_SetString (PyExc_TypeError,
		       _("Expected a string or unicode object."));
      unicode_str = NULL;
    }

  return unicode_str;
}

/* Returns a newly allocated string with the contents of the given unicode
   string object converted to CHARSET.  If an error occurs during the
   conversion, NULL will be returned and a python exception will be set.

   The caller is responsible for xfree'ing the string.  */
static char *
unicode_to_encoded_string (PyObject *unicode_str, const char *charset)
{
  char *result;
  PyObject *string;

  /* Translate string to named charset.  */
  string = PyUnicode_AsEncodedString (unicode_str, charset, NULL);
  if (string == NULL)
    return NULL;

  result = xstrdup (PyString_AsString (string));

  Py_DECREF (string);

  return result;
}

/* Returns a PyObject with the contents of the given unicode string
   object converted to a named charset.  If an error occurs during
   the conversion, NULL will be returned and a python exception will
   be set.  */
static PyObject *
unicode_to_encoded_python_string (PyObject *unicode_str, const char *charset)
{
  PyObject *string;

  /* Translate string to named charset.  */
  string = PyUnicode_AsEncodedString (unicode_str, charset, NULL);
  if (string == NULL)
    return NULL;

  return string;
}

/* Returns a newly allocated string with the contents of the given unicode
   string object converted to the target's charset.  If an error occurs during
   the conversion, NULL will be returned and a python exception will be set.

   The caller is responsible for xfree'ing the string.  */
char *
unicode_to_target_string (PyObject *unicode_str)
{
  return unicode_to_encoded_string (unicode_str,
				    target_charset (python_gdbarch));
}

/* Returns a PyObject with the contents of the given unicode string
   object converted to the target's charset.  If an error occurs
   during the conversion, NULL will be returned and a python exception
   will be set.  */
PyObject *
unicode_to_target_python_string (PyObject *unicode_str)
{
  return unicode_to_encoded_python_string (unicode_str,
					   target_charset (python_gdbarch));
}

/* Converts a python string (8-bit or unicode) to a target string in
   the target's charset.  Returns NULL on error, with a python exception set.

   The caller is responsible for xfree'ing the string.  */
char *
python_string_to_target_string (PyObject *obj)
{
  PyObject *str;
  char *result;

  str = python_string_to_unicode (obj);
  if (str == NULL)
    return NULL;

  result = unicode_to_target_string (str);
  Py_DECREF (str);
  return result;
}

/* Converts a python string (8-bit or unicode) to a target string in the
   target's charset.  Returns NULL on error, with a python exception
   set.  */
PyObject *
python_string_to_target_python_string (PyObject *obj)
{
  PyObject *str;
  PyObject *result;

  str = python_string_to_unicode (obj);
  if (str == NULL)
    return NULL;

  result = unicode_to_target_python_string (str);
  Py_DECREF (str);
  return result;
}

/* Converts a python string (8-bit or unicode) to a target string in
   the host's charset.  Returns NULL on error, with a python exception set.

   The caller is responsible for xfree'ing the string.  */
char *
python_string_to_host_string (PyObject *obj)
{
  PyObject *str;
  char *result;

  str = python_string_to_unicode (obj);
  if (str == NULL)
    return NULL;

  result = unicode_to_encoded_string (str, host_charset ()); 
  Py_DECREF (str);
  return result;
}

/* Converts a target string of LENGTH bytes in the target's charset to a
   Python Unicode string. If LENGTH is -1, convert until a null byte is found.

   Returns NULL on error, with a python exception set.  */
PyObject *
target_string_to_unicode (const gdb_byte *str, int length)
{
  if (length == -1)
    length = strlen (str);

  return PyUnicode_Decode (str, length, target_charset (python_gdbarch), NULL);
}

/* Return true if OBJ is a Python string or unicode object, false
   otherwise.  */

int
gdbpy_is_string (PyObject *obj)
{
  return PyString_Check (obj) || PyUnicode_Check (obj);
}

/* Return the string representation of OBJ, i.e., str (obj).
   Space for the result is malloc'd, the caller must free.
   If the result is NULL a python error occurred, the caller must clear it.  */

char *
gdbpy_obj_to_string (PyObject *obj)
{
  PyObject *str_obj = PyObject_Str (obj);

  if (str_obj != NULL)
    {
      char *msg = xstrdup (PyString_AsString (str_obj));

      Py_DECREF (str_obj);
      return msg;
    }

  return NULL;
}

/* Return the string representation of the exception represented by
   TYPE, VALUE which is assumed to have been obtained with PyErr_Fetch,
   i.e., the error indicator is currently clear.
   Space for the result is malloc'd, the caller must free.
   If the result is NULL a python error occurred, the caller must clear it.  */

char *
gdbpy_exception_to_string (PyObject *ptype, PyObject *pvalue)
{
  PyObject *str_obj = PyObject_Str (pvalue);
  char *str;

  /* There are a few cases to consider.
     For example:
     pvalue is a string when PyErr_SetString is used.
     pvalue is not a string when raise "foo" is used, instead it is None
     and ptype is "foo".
     So the algorithm we use is to print `str (pvalue)' if it's not
     None, otherwise we print `str (ptype)'.
     Using str (aka PyObject_Str) will fetch the error message from
     gdb.GdbError ("message").  */

  if (pvalue && pvalue != Py_None)
    str = gdbpy_obj_to_string (pvalue);
  else
    str = gdbpy_obj_to_string (ptype);

  return str;
}