Python Codec Registry and support functions, written by Marc-Andre
Lemburg.
diff --git a/Python/codecs.c b/Python/codecs.c
new file mode 100644
index 0000000..5075a20
--- /dev/null
+++ b/Python/codecs.c
@@ -0,0 +1,382 @@
+/* ------------------------------------------------------------------------
+
+ Python Codec Registry and support functions
+
+Written by Marc-Andre Lemburg (mal@lemburg.com).
+
+(c) Copyright CNRI, All Rights Reserved. NO WARRANTY.
+
+ ------------------------------------------------------------------------ */
+
+#include "Python.h"
+#include <ctype.h>
+
+/* --- Globals ------------------------------------------------------------ */
+
+static PyObject *_PyCodec_SearchPath;
+static PyObject *_PyCodec_SearchCache;
+
+/* Flag used for lazy import of the standard encodings package */
+static int import_encodings_called = 0;
+
+/* --- Codec Registry ----------------------------------------------------- */
+
+/* Import the standard encodings package which will register the first
+ codec search function.
+
+ This is done in a lazy way so that the Unicode implementation does
+ not downgrade startup time of scripts not needing it.
+
+ Errors are silently ignored by this function. Only one try is made.
+
+*/
+
+static
+void import_encodings()
+{
+ PyObject *mod;
+
+ import_encodings_called = 1;
+ mod = PyImport_ImportModule("encodings");
+ if (mod == NULL) {
+ PyErr_Clear();
+ return;
+ }
+ Py_DECREF(mod);
+}
+
+/* Register a new codec search function.
+
+ The search_function's refcount is incremented by this function. */
+
+int PyCodec_Register(PyObject *search_function)
+{
+ if (!import_encodings_called)
+ import_encodings();
+ if (search_function == NULL) {
+ PyErr_BadArgument();
+ return -1;
+ }
+ if (!PyCallable_Check(search_function)) {
+ PyErr_SetString(PyExc_TypeError,
+ "argument must be callable");
+ return -1;
+ }
+ return PyList_Append(_PyCodec_SearchPath, search_function);
+}
+
+static
+PyObject *lowercasestring(const char *string)
+{
+ register int i;
+ int len = strlen(string);
+ char *p;
+ PyObject *v;
+
+ v = PyString_FromStringAndSize(NULL, len);
+ if (v == NULL)
+ return NULL;
+ p = PyString_AS_STRING(v);
+ for (i = 0; i < len; i++)
+ p[i] = tolower(string[i]);
+ return v;
+}
+
+/* Lookup the given encoding and return a tuple providing the codec
+ facilities.
+
+ The encoding string is looked up converted to all lower-case
+ characters. This makes encodings looked up through this mechanism
+ effectively case-insensitive.
+
+ If no codec is found, a KeyError is set and NULL returned. */
+
+PyObject *_PyCodec_Lookup(const char *encoding)
+{
+ PyObject *result, *args = NULL, *v;
+ int i, len;
+
+ if (!import_encodings_called)
+ import_encodings();
+
+ /* Convert the encoding to a lower-cased Python string */
+ v = lowercasestring(encoding);
+ if (v == NULL)
+ goto onError;
+ PyString_InternInPlace(&v);
+
+ /* First, try to lookup the name in the registry dictionary */
+ result = PyDict_GetItem(_PyCodec_SearchCache, v);
+ if (result != NULL) {
+ Py_INCREF(result);
+ return result;
+ }
+
+ /* Next, scan the search functions in order of registration */
+ len = PyList_Size(_PyCodec_SearchPath);
+ if (len < 0)
+ goto onError;
+
+ args = PyTuple_New(1);
+ if (args == NULL)
+ goto onError;
+ PyTuple_SET_ITEM(args,0,v);
+
+ for (i = 0; i < len; i++) {
+ PyObject *func;
+
+ func = PyList_GetItem(_PyCodec_SearchPath, i);
+ if (func == NULL)
+ goto onError;
+ result = PyEval_CallObject(func,args);
+ if (result == NULL)
+ goto onError;
+ if (result == Py_None) {
+ Py_DECREF(result);
+ continue;
+ }
+ if (!PyTuple_Check(result) || PyTuple_GET_SIZE(result) != 4) {
+ PyErr_SetString(PyExc_TypeError,
+ "codec search functions must return 4-tuples");
+ Py_DECREF(result);
+ goto onError;
+ }
+ break;
+ }
+ if (i == len) {
+ /* XXX Perhaps we should cache misses too ? */
+ PyErr_SetString(PyExc_LookupError,
+ "unkown encoding");
+ goto onError;
+ }
+
+ /* Cache and return the result */
+ PyDict_SetItem(_PyCodec_SearchCache, v, result);
+ Py_DECREF(args);
+ return result;
+
+ onError:
+ Py_XDECREF(args);
+ return NULL;
+}
+
+static
+PyObject *args_tuple(PyObject *object,
+ const char *errors)
+{
+ PyObject *args;
+
+ args = PyTuple_New(1 + (errors != NULL));
+ if (args == NULL)
+ return NULL;
+ Py_INCREF(object);
+ PyTuple_SET_ITEM(args,0,object);
+ if (errors) {
+ PyObject *v;
+
+ v = PyString_FromString(errors);
+ if (v == NULL) {
+ Py_DECREF(args);
+ return NULL;
+ }
+ PyTuple_SET_ITEM(args, 1, v);
+ }
+ return args;
+}
+
+/* Build a codec by calling factory(stream[,errors]) or just
+ factory(errors) depending on whether the given parameters are
+ non-NULL. */
+
+static
+PyObject *build_stream_codec(PyObject *factory,
+ PyObject *stream,
+ const char *errors)
+{
+ PyObject *args, *codec;
+
+ args = args_tuple(stream, errors);
+ if (args == NULL)
+ return NULL;
+
+ codec = PyEval_CallObject(factory, args);
+ Py_DECREF(args);
+ return codec;
+}
+
+/* Convenience APIs to query the Codec registry.
+
+ All APIs return a codec object with incremented refcount.
+
+ */
+
+PyObject *PyCodec_Encoder(const char *encoding)
+{
+ PyObject *codecs;
+ PyObject *v;
+
+ codecs = _PyCodec_Lookup(encoding);
+ if (codecs == NULL)
+ goto onError;
+ v = PyTuple_GET_ITEM(codecs,0);
+ Py_INCREF(v);
+ return v;
+
+ onError:
+ return NULL;
+}
+
+PyObject *PyCodec_Decoder(const char *encoding)
+{
+ PyObject *codecs;
+ PyObject *v;
+
+ codecs = _PyCodec_Lookup(encoding);
+ if (codecs == NULL)
+ goto onError;
+ v = PyTuple_GET_ITEM(codecs,1);
+ Py_INCREF(v);
+ return v;
+
+ onError:
+ return NULL;
+}
+
+PyObject *PyCodec_StreamReader(const char *encoding,
+ PyObject *stream,
+ const char *errors)
+{
+ PyObject *codecs;
+
+ codecs = _PyCodec_Lookup(encoding);
+ if (codecs == NULL)
+ goto onError;
+ return build_stream_codec(PyTuple_GET_ITEM(codecs,2),stream,errors);
+
+ onError:
+ return NULL;
+}
+
+PyObject *PyCodec_StreamWriter(const char *encoding,
+ PyObject *stream,
+ const char *errors)
+{
+ PyObject *codecs;
+
+ codecs = _PyCodec_Lookup(encoding);
+ if (codecs == NULL)
+ goto onError;
+ return build_stream_codec(PyTuple_GET_ITEM(codecs,3),stream,errors);
+
+ onError:
+ return NULL;
+}
+
+/* Encode an object (e.g. an Unicode object) using the given encoding
+ and return the resulting encoded object (usually a Python string).
+
+ errors is passed to the encoder factory as argument if non-NULL. */
+
+PyObject *PyCodec_Encode(PyObject *object,
+ const char *encoding,
+ const char *errors)
+{
+ PyObject *encoder = NULL;
+ PyObject *args = NULL, *result;
+ PyObject *v;
+
+ encoder = PyCodec_Encoder(encoding);
+ if (encoder == NULL)
+ goto onError;
+
+ args = args_tuple(object, errors);
+ if (args == NULL)
+ goto onError;
+
+ result = PyEval_CallObject(encoder,args);
+ if (result == NULL)
+ goto onError;
+
+ if (!PyTuple_Check(result) ||
+ PyTuple_GET_SIZE(result) != 2) {
+ PyErr_SetString(PyExc_TypeError,
+ "encoder must return a tuple (object,integer)");
+ goto onError;
+ }
+ v = PyTuple_GET_ITEM(result,0);
+ Py_INCREF(v);
+ /* We don't check or use the second (integer) entry. */
+
+ Py_DECREF(args);
+ Py_DECREF(encoder);
+ Py_DECREF(result);
+ return v;
+
+ onError:
+ Py_XDECREF(args);
+ Py_XDECREF(encoder);
+ return NULL;
+}
+
+/* Decode an object (usually a Python string) using the given encoding
+ and return an equivalent object (e.g. an Unicode object).
+
+ errors is passed to the decoder factory as argument if non-NULL. */
+
+PyObject *PyCodec_Decode(PyObject *object,
+ const char *encoding,
+ const char *errors)
+{
+ PyObject *decoder = NULL;
+ PyObject *args = NULL, *result = NULL;
+ PyObject *v;
+
+ decoder = PyCodec_Decoder(encoding);
+ if (decoder == NULL)
+ goto onError;
+
+ args = args_tuple(object, errors);
+ if (args == NULL)
+ goto onError;
+
+ result = PyEval_CallObject(decoder,args);
+ if (result == NULL)
+ goto onError;
+ if (!PyTuple_Check(result) ||
+ PyTuple_GET_SIZE(result) != 2) {
+ PyErr_SetString(PyExc_TypeError,
+ "decoder must return a tuple (object,integer)");
+ goto onError;
+ }
+ v = PyTuple_GET_ITEM(result,0);
+ Py_INCREF(v);
+ /* We don't check or use the second (integer) entry. */
+
+ Py_DECREF(args);
+ Py_DECREF(decoder);
+ Py_DECREF(result);
+ return v;
+
+ onError:
+ Py_XDECREF(args);
+ Py_XDECREF(decoder);
+ Py_XDECREF(result);
+ return NULL;
+}
+
+void _PyCodecRegistry_Init()
+{
+ if (_PyCodec_SearchPath == NULL)
+ _PyCodec_SearchPath = PyList_New(0);
+ if (_PyCodec_SearchCache == NULL)
+ _PyCodec_SearchCache = PyDict_New();
+ if (_PyCodec_SearchPath == NULL ||
+ _PyCodec_SearchCache == NULL)
+ Py_FatalError("can't intialize codec registry");
+}
+
+void _PyCodecRegistry_Fini()
+{
+ Py_XDECREF(_PyCodec_SearchPath);
+ Py_XDECREF(_PyCodec_SearchCache);
+}