int Trie_has_prefix(const Trie* trie, const char *prefix)
{
int first, last, mid;
if(!prefix[0]) {
return 1;
}
/* The transitions are stored in alphabetical order. Do a binary
* search to find the proper one.
*/
first = 0;
last = trie->num_transitions-1;
while(first <= last) {
Transition* transition;
char *suffix;
int suffixlen, prefixlen, minlen;
int c;
mid = (first+last)/2;
transition = &trie->transitions[mid];
suffix = transition->suffix;
suffixlen = strlen(suffix);
prefixlen = strlen(prefix);
minlen = (suffixlen < prefixlen) ? suffixlen : prefixlen;
c = strncmp(prefix, suffix, minlen);
if(c < 0)
last = mid-1;
else if(c > 0)
first = mid+1;
else
return Trie_has_prefix(transition->next, prefix+minlen);
}
return 0;
}
static PyObject *
trie_has_prefix(trieobject *mp, PyObject *py_prefix)
{
unsigned char *prefix;
int has_prefix;
/* Make sure prefix is a string. */
if(!PyString_Check(py_prefix)) {
PyErr_SetString(PyExc_TypeError, "k must be a string");
return NULL;
}
prefix = (unsigned char *)PyString_AS_STRING(py_prefix);
has_prefix = Trie_has_prefix(mp->trie, prefix);
return PyInt_FromLong((long)has_prefix);
}
static PyObject *
trie_has_prefix(trieobject *mp, PyObject *py_prefix)
{
const char *prefix;
int has_prefix;
#ifdef IS_PY3K
PyObject* bytes;
#endif
/* Make sure prefix is a string. */
#ifdef IS_PY3K
if(!PyUnicode_Check(py_prefix)) {
#else
if(!PyString_Check(py_prefix)) {
#endif
PyErr_SetString(PyExc_TypeError, "prefix must be a string");
return NULL;
}
#ifdef IS_PY3K
bytes = PyUnicode_AsASCIIString(py_prefix);
if(!bytes) {
PyErr_SetString(PyExc_TypeError, "prefix must be an ASCII string");
return NULL;
}
prefix = PyBytes_AsString(bytes);
#else
prefix = PyString_AS_STRING(py_prefix);
#endif
has_prefix = Trie_has_prefix(mp->trie, prefix);
#ifdef IS_PY3K
Py_DECREF(bytes);
return PyLong_FromLong((long)has_prefix);
#else
return PyInt_FromLong((long)has_prefix);
#endif
}
static PyObject *
trie_has_prefix_onearg(trieobject *mp, PyObject *py_args)
{
PyObject *py_arg;
if(!PyArg_ParseTuple(py_args, "O", &py_arg))
return NULL;
return trie_has_prefix(mp, py_arg);
}
