needforspeed: partition implementation, part two.

feel free to improve the documentation and the docstrings.

Doc/lib/libstdtypes.tex

@@ -727,6 +727,14 @@ a prefix; rather, all combinations of its values are stripped:
 \versionchanged[Support for the \var{chars} argument]{2.2.2}
 \end{methoddesc}
 
+\begin{methoddesc}[string]{partition}{sep}
+Splits the string at the \var{sep}, and return a 3-tuple containing
+the part before the separator, the separator itself, and the part
+after the separator.  If the separator is not found, return a 3-tuple
+containing the string itself, followed by two empty strings.
+\versionadded{2.5}
+\end{methoddesc}
+
 \begin{methoddesc}[string]{replace}{old, new\optional{, count}}
 Return a copy of the string with all occurrences of substring
 \var{old} replaced by \var{new}.  If the optional argument

Include/unicodeobject.h

@@ -184,6 +184,7 @@ typedef PY_UNICODE_TYPE Py_UNICODE;
 # define PyUnicode_GetMax PyUnicodeUCS2_GetMax
 # define PyUnicode_GetSize PyUnicodeUCS2_GetSize
 # define PyUnicode_Join PyUnicodeUCS2_Join
+# define PyUnicode_Partition PyUnicodeUCS2_Partition
 # define PyUnicode_Replace PyUnicodeUCS2_Replace
 # define PyUnicode_Resize PyUnicodeUCS2_Resize
 # define PyUnicode_SetDefaultEncoding PyUnicodeUCS2_SetDefaultEncoding
@@ -259,6 +260,7 @@ typedef PY_UNICODE_TYPE Py_UNICODE;
 # define PyUnicode_GetMax PyUnicodeUCS4_GetMax
 # define PyUnicode_GetSize PyUnicodeUCS4_GetSize
 # define PyUnicode_Join PyUnicodeUCS4_Join
+# define PyUnicode_Partition PyUnicodeUCS4_Partition
 # define PyUnicode_Replace PyUnicodeUCS4_Replace
 # define PyUnicode_Resize PyUnicodeUCS4_Resize
 # define PyUnicode_SetDefaultEncoding PyUnicodeUCS4_SetDefaultEncoding
@@ -1018,6 +1020,13 @@ PyAPI_FUNC(PyObject*) PyUnicode_Splitlines(
     int keepends		/* If true, line end markers are included */
     );		
 
+/* Partition a string using a given separator. */
+
+PyAPI_FUNC(PyObject*) PyUnicode_Partition(
+    PyObject *s,		/* String to partition */
+    PyObject *sep		/* String separator */
+    );		
+
 /* Split a string giving a list of Unicode strings.
 
    If sep is NULL, splitting will be done at all whitespace

Lib/test/string_tests.py

@@ -900,6 +900,21 @@ def test_inplace_rewrites(self):
         self.checkequal('A', 'a', 'title')
         self.checkequal(True, 'a', 'islower')
 
+    def test_partition(self):
+
+        self.checkequal(('this', ' is ', 'the partition method'),
+            'this is the partition method', 'partition', ' is ')
+
+        # from raymond's original specification
+        S = 'http://www.python.org'
+        self.checkequal(('http', '://', 'www.python.org'), S, 'partition', '://')
+        self.checkequal(('http://www.python.org', '', ''), S, 'partition', '?')
+        self.checkequal(('', 'http://', 'www.python.org'), S, 'partition', 'http://')
+        self.checkequal(('http://www.python.', 'org', ''), S, 'partition', 'org')
+
+        self.checkraises(ValueError, S, 'partition', '')
+        self.checkraises(TypeError, S, 'partition', None)
+
 
 class MixinStrStringUserStringTest:
     # Additional tests for 8bit strings, i.e. str, UserString and

Objects/stringobject.c

@@ -1610,20 +1610,20 @@ string_partition(PyStringObject *self, PyObject *args)
 {
 	Py_ssize_t len = PyString_GET_SIZE(self), sep_len, pos;
 	const char *str = PyString_AS_STRING(self), *sep;
-	PyObject *sepobj;
+	PyObject *sep_obj;
 	PyObject * out;
 
-	if (!PyArg_ParseTuple(args, "O:partition", &sepobj))
+	if (!PyArg_ParseTuple(args, "O:partition", &sep_obj))
 		return NULL;
-	if (PyString_Check(sepobj)) {
+	if (PyString_Check(sep_obj)) {
-		sep = PyString_AS_STRING(sepobj);
+		sep = PyString_AS_STRING(sep_obj);
-		sep_len = PyString_GET_SIZE(sepobj);
+		sep_len = PyString_GET_SIZE(sep_obj);
 	}
-#ifdef Py_USING_UNICODE_NOTYET
+#ifdef Py_USING_UNICODE
-	else if (PyUnicode_Check(sepobj))
+	else if (PyUnicode_Check(sep_obj))
-		return PyUnicode_Partition((PyObject *)self, sepobj);
+		return PyUnicode_Partition((PyObject *)self, sep_obj);
 #endif
-	else if (PyObject_AsCharBuffer(sepobj, &sep, &sep_len))
+	else if (PyObject_AsCharBuffer(sep_obj, &sep, &sep_len))
 		return NULL;
 
 	if (sep_len == 0) {
@@ -1644,13 +1644,13 @@ string_partition(PyStringObject *self, PyObject *args)
 		Py_INCREF(nullstring);
 		PyTuple_SET_ITEM(out, 2, (PyObject*) nullstring);
 	} else {
-		Py_INCREF(sepobj);
+		PyObject* obj;
 		PyTuple_SET_ITEM(out, 0, PyString_FromStringAndSize(str, pos));
-		PyTuple_SET_ITEM(out, 1, sepobj);
+		Py_INCREF(sep_obj);
-		PyTuple_SET_ITEM(out, 2,
+		PyTuple_SET_ITEM(out, 1, sep_obj);
-			PyString_FromStringAndSize(str + sep_len + pos,
+		pos += sep_len;
-						   len - sep_len - pos)
+		obj = PyString_FromStringAndSize(str + pos, len - pos);
-			);
+		PyTuple_SET_ITEM(out, 2, obj);
 		if (PyErr_Occurred()) {
 			Py_DECREF(out);
 			return NULL;

Objects/unicodeobject.c

@@ -4,6 +4,9 @@ Unicode implementation based on original code by Fredrik Lundh,
 modified by Marc-Andre Lemburg <mal@lemburg.com> according to the
 Unicode Integration Proposal (see file Misc/unicode.txt).
 
+Major speed upgrades to the method implementations at the Reykjavik
+NeedForSpeed sprint, by Fredrik Lundh and Andrew Dalke.
+
 Copyright (c) Corporation for National Research Initiatives.
 
 --------------------------------------------------------------------
@@ -193,6 +196,7 @@ int unicode_resize(register PyUnicodeObject *unicode,
     /* Resizing shared object (unicode_empty or single character
        objects) in-place is not allowed. Use PyUnicode_Resize()
        instead ! */
+
     if (unicode == unicode_empty || 
 	(unicode->length == 1 && 
 	 unicode->str[0] < 256U &&
@@ -202,8 +206,11 @@ int unicode_resize(register PyUnicodeObject *unicode,
         return -1;
     }
 
-    /* We allocate one more byte to make sure the string is
+    /* We allocate one more byte to make sure the string is Ux0000 terminated.
-       Ux0000 terminated -- XXX is this needed ? */
+       The overallocation is also used by fastsearch, which assumes that it's
+       safe to look at str[length] (without makeing any assumptions about what
+       it contains). */
+
     oldstr = unicode->str;
     PyMem_RESIZE(unicode->str, Py_UNICODE, length + 1);
     if (!unicode->str) {
@@ -3859,8 +3866,6 @@ int PyUnicode_EncodeDecimal(Py_UNICODE *s,
 
 /* --- Helpers ------------------------------------------------------------ */
 
-#define USE_FAST /* experimental fast search implementation */
-
 /* fast search/count implementation, based on a mix between boyer-
    moore and horspool, with a few more bells and whistles on the top.
    for some more background, see: http://effbot.org/stringlib */
@@ -3936,10 +3941,8 @@ fastsearch(Py_UNICODE* s, Py_ssize_t n, Py_UNICODE* p, Py_ssize_t m, int mode)
             /* miss: check if next character is part of pattern */
             if (!(mask & (1 << (s[i+m] & 0x1F))))
                 i = i + m;
-            else {
+            else
                 i = i + skip;
-                continue;
-            }
         } else {
             /* skip: check if next character is part of pattern */
             if (!(mask & (1 << (s[i+m] & 0x1F))))
@@ -3973,23 +3976,13 @@ LOCAL(Py_ssize_t) count(PyUnicodeObject *self,
     if (substring->length == 0)
 	return (end - start + 1);
 
-#ifdef USE_FAST
     count = fastsearch(
         PyUnicode_AS_UNICODE(self) + start, end - start,
         substring->str, substring->length, FAST_COUNT
         );
+
     if (count < 0)
         count = 0; /* no match */
-#else    
-    end -= substring->length;
-
-    while (start <= end)
-        if (Py_UNICODE_MATCH(self, start, substring)) {
-            count++;
-            start += substring->length;
-        } else
-            start++;
-#endif
 
     return count;
 }
@@ -4040,30 +4033,19 @@ static Py_ssize_t findstring(PyUnicodeObject *self,
     if (substring->length == 0)
 	return (direction > 0) ? start : end;
 
-#ifdef USE_FAST
     if (direction > 0) {
         Py_ssize_t pos = fastsearch(
             PyUnicode_AS_UNICODE(self) + start, end - start,
             substring->str, substring->length, FAST_SEARCH
             );
-        if (pos < 0)
+        if (pos >= 0)
-            return pos;
+            return pos + start;
-        return pos + start;
+    } else {
-    }
+        end -= substring->length;
-#endif
-
-    end -= substring->length;
-
-    if (direction < 0) {
         for (; end >= start; end--)
             if (Py_UNICODE_MATCH(self, end, substring))
                 return end;
-    } else {
-        for (; start <= end; start++)
-            if (Py_UNICODE_MATCH(self, start, substring))
-                return start;
     }
-
     return -1;
 }
 
@@ -5167,11 +5149,8 @@ int PyUnicode_Contains(PyObject *container,
 		       PyObject *element)
 {
     PyUnicodeObject *u, *v;
-    int result;
     Py_ssize_t size;
-#ifdef USE_FAST
     Py_ssize_t pos;
-#endif
 
     /* Coerce the two arguments */
     v = (PyUnicodeObject *) PyUnicode_FromObject(element);
@@ -5189,44 +5168,19 @@ int PyUnicode_Contains(PyObject *container,
 
     size = PyUnicode_GET_SIZE(v);
     if (!size) {
-        result = 1;
+        pos = 0;
         goto done;
     }
 
-#ifdef USE_FAST
     pos = fastsearch(
         PyUnicode_AS_UNICODE(u), PyUnicode_GET_SIZE(u),
         PyUnicode_AS_UNICODE(v), size, FAST_SEARCH
         );
-    result = (pos != -1);
-#else    
-    result = 0;
-
-    if (size == 1) {
-        Py_UNICODE chr = PyUnicode_AS_UNICODE(v)[0];
-        Py_UNICODE* ptr = PyUnicode_AS_UNICODE(u);
-	Py_UNICODE* end = ptr + PyUnicode_GET_SIZE(u);
-	for (; ptr < end; ptr++) {
-	    if (*ptr == chr) {
-		result = 1;
-		break;
-	    }
-	}
-    } else {
-        Py_ssize_t start = 0;
-        Py_ssize_t end = PyUnicode_GET_SIZE(u) - size;
-        for (; start <= end; start++)
-            if (Py_UNICODE_MATCH(u, start, v)) {
-                result = 1;
-                break;
-            }
-    }
-#endif
 
 done:
     Py_DECREF(u);
     Py_DECREF(v);
-    return result;
+    return (pos != -1);
 }
 
 /* Concat to string or Unicode object giving a new Unicode object. */
@@ -6335,6 +6289,84 @@ unicode_split(PyUnicodeObject *self, PyObject *args)
 	return PyUnicode_Split((PyObject *)self, substring, maxcount);
 }
 
+PyObject *
+PyUnicode_Partition(PyObject *str_in, PyObject *sep_in)
+{
+    PyObject* str_obj;
+    PyObject* sep_obj;
+    Py_UNICODE *str, *sep;
+    Py_ssize_t len, sep_len, pos;
+    PyObject* out;
+    
+    str_obj = PyUnicode_FromObject(str_in);
+    if (!str_obj)
+	return NULL;
+    sep_obj = PyUnicode_FromObject(sep_in);
+    if (!sep_obj)
+        goto error;
+
+    str = PyUnicode_AS_UNICODE(str_obj);
+    len = PyUnicode_GET_SIZE(str_obj);
+
+    sep = PyUnicode_AS_UNICODE(sep_obj);
+    sep_len = PyUnicode_GET_SIZE(sep_obj);
+
+    if (sep_len == 0) {
+        PyErr_SetString(PyExc_ValueError, "empty separator");
+        goto error;
+    }
+
+    out = PyTuple_New(3);
+    if (!out)
+        goto error;
+
+    pos = fastsearch(str, len, sep, sep_len, FAST_SEARCH);
+    if (pos < 0) {
+        Py_INCREF(str_obj);
+        PyTuple_SET_ITEM(out, 0, (PyObject*) str_obj);
+        Py_INCREF(unicode_empty);
+        PyTuple_SET_ITEM(out, 1, (PyObject*) unicode_empty);
+        Py_INCREF(unicode_empty);
+        PyTuple_SET_ITEM(out, 2, (PyObject*) unicode_empty);
+    } else {
+        PyObject* obj;
+        PyTuple_SET_ITEM(out, 0, PyUnicode_FromUnicode(str, pos));
+        Py_INCREF(sep_obj);
+        PyTuple_SET_ITEM(out, 1, sep_obj);
+        obj = PyUnicode_FromUnicode(str + sep_len + pos, len - sep_len - pos);
+        PyTuple_SET_ITEM(out, 2, obj);
+        if (PyErr_Occurred()) {
+            Py_DECREF(out);
+            goto error;
+        }
+    }
+
+    return out;
+
+error:
+    Py_XDECREF(sep_obj);
+    Py_DECREF(str_obj);
+    return NULL;
+}
+
+PyDoc_STRVAR(partition__doc__,
+"S.partition(sep) -> (head, sep, tail)\n\
+\n\
+Searches for the separator sep in S, and returns the part before it,\n\
+the separator itself, and the part after it.  If the separator is not\n\
+found, returns S and two empty strings.");
+
+static PyObject*
+unicode_partition(PyUnicodeObject *self, PyObject *args)
+{
+    PyObject *separator;
+
+    if (!PyArg_ParseTuple(args, "O:partition", &separator))
+        return NULL;
+
+    return PyUnicode_Partition((PyObject *)self, separator);
+}
+
 PyObject *PyUnicode_RSplit(PyObject *s,
 			   PyObject *sep,
 			   Py_ssize_t maxsplit)
@@ -6588,6 +6620,7 @@ static PyMethodDef unicode_methods[] = {
     {"count", (PyCFunction) unicode_count, METH_VARARGS, count__doc__},
     {"expandtabs", (PyCFunction) unicode_expandtabs, METH_VARARGS, expandtabs__doc__},
     {"find", (PyCFunction) unicode_find, METH_VARARGS, find__doc__},
+    {"partition", (PyCFunction) unicode_partition, METH_VARARGS, partition__doc__},
     {"index", (PyCFunction) unicode_index, METH_VARARGS, index__doc__},
     {"ljust", (PyCFunction) unicode_ljust, METH_VARARGS, ljust__doc__},
     {"lower", (PyCFunction) unicode_lower, METH_NOARGS, lower__doc__},