Modules/_sqlite/microprotocols.c

   1 /* microprotocols.c - minimalist and non-validating protocols implementation
   2  *
   3  * Copyright (C) 2003-2004 Federico Di Gregorio <fog@debian.org>
   4  *
   5  * This file is part of psycopg and was adapted for pysqlite. Federico Di
   6  * Gregorio gave the permission to use it within pysqlite under the following
   7  * license:
   8  *
   9  * This software is provided 'as-is', without any express or implied
  10  * warranty.  In no event will the authors be held liable for any damages
  11  * arising from the use of this software.
  12  *
  13  * Permission is granted to anyone to use this software for any purpose,
  14  * including commercial applications, and to alter it and redistribute it
  15  * freely, subject to the following restrictions:
  16  *
  17  * 1. The origin of this software must not be misrepresented; you must not
  18  *    claim that you wrote the original software. If you use this software
  19  *    in a product, an acknowledgment in the product documentation would be
  20  *    appreciated but is not required.
  21  * 2. Altered source versions must be plainly marked as such, and must not be
  22  *    misrepresented as being the original software.
  23  * 3. This notice may not be removed or altered from any source distribution.
  24  */
  25
  26 #include <Python.h>
  27 #include <structmember.h>
  28
  29 #include "cursor.h"
  30 #include "microprotocols.h"
  31 #include "prepare_protocol.h"
  32
  33
  34 /** the adapters registry **/
  35
  36 PyObject *psyco_adapters;
  37
  38 /* pysqlite_microprotocols_init - initialize the adapters dictionary */
  39
  40 int
  41 pysqlite_microprotocols_init(PyObject *dict)
  42 {
  43     /* create adapters dictionary and put it in module namespace */
  44     if ((psyco_adapters = PyDict_New()) == NULL) {
  45         return -1;
  46     }
  47
  48     return PyDict_SetItemString(dict, "adapters", psyco_adapters);
  49 }
  50
  51
  52 /* pysqlite_microprotocols_add - add a reverse type-caster to the dictionary */
  53
  54 int
  55 pysqlite_microprotocols_add(PyTypeObject *type, PyObject *proto, PyObject *cast)
  56 {
  57     PyObject* key;
  58     int rc;
  59
  60     if (proto == NULL) proto = (PyObject*)&pysqlite_PrepareProtocolType;
  61
  62     key = Py_BuildValue("(OO)", (PyObject*)type, proto);
  63     if (!key) {
  64         return -1;
  65     }
  66
  67     rc = PyDict_SetItem(psyco_adapters, key, cast);
  68     Py_DECREF(key);
  69
  70     return rc;
  71 }
  72
  73 /* pysqlite_microprotocols_adapt - adapt an object to the built-in protocol */
  74
  75 PyObject *
  76 pysqlite_microprotocols_adapt(PyObject *obj, PyObject *proto, PyObject *alt)
  77 {
  78     PyObject *adapter, *key;
  79
  80     /* we don't check for exact type conformance as specified in PEP 246
  81        because the pysqlite_PrepareProtocolType type is abstract and there is no
  82        way to get a quotable object to be its instance */
  83
  84     /* look for an adapter in the registry */
  85     key = Py_BuildValue("(OO)", (PyObject*)obj->ob_type, proto);
  86     if (!key) {
  87         return NULL;
  88     }
  89     adapter = PyDict_GetItem(psyco_adapters, key);
  90     Py_DECREF(key);
  91     if (adapter) {
  92         PyObject *adapted = PyObject_CallFunctionObjArgs(adapter, obj, NULL);
  93         return adapted;
  94     }
  95
  96     /* try to have the protocol adapt this object*/
  97     if (PyObject_HasAttrString(proto, "__adapt__")) {
  98         PyObject *adapted = PyObject_CallMethod(proto, "__adapt__", "O", obj);
  99         if (adapted) {
 100             if (adapted != Py_None) {
 101                 return adapted;
 102             } else {
 103                 Py_DECREF(adapted);
 104             }
 105         }
 106
 107         if (PyErr_Occurred() && !PyErr_ExceptionMatches(PyExc_TypeError))
 108             return NULL;
 109     }
 110
 111     /* and finally try to have the object adapt itself */
 112     if (PyObject_HasAttrString(obj, "__conform__")) {
 113         PyObject *adapted = PyObject_CallMethod(obj, "__conform__","O", proto);
 114         if (adapted) {
 115             if (adapted != Py_None) {
 116                 return adapted;
 117             } else {
 118                 Py_DECREF(adapted);
 119             }
 120         }
 121
 122         if (PyErr_Occurred() && !PyErr_ExceptionMatches(PyExc_TypeError)) {
 123             return NULL;
 124         }
 125     }
 126
 127     /* else set the right exception and return NULL */
 128     PyErr_SetString(pysqlite_ProgrammingError, "can't adapt");
 129     return NULL;
 130 }
 131
 132 /** module-level functions **/
 133
 134 PyObject *
 135 pysqlite_adapt(pysqlite_Cursor *self, PyObject *args)
 136 {
 137     PyObject *obj, *alt = NULL;
 138     PyObject *proto = (PyObject*)&pysqlite_PrepareProtocolType;
 139
 140     if (!PyArg_ParseTuple(args, "O|OO", &obj, &proto, &alt)) return NULL;
 141     return pysqlite_microprotocols_adapt(obj, proto, alt);
 142 }