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* Beef-up tests for str.count().

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* Speed-up str.count() by using memchr() to fly between first char matches.
This commit is contained in:
Raymond Hettinger 2005-02-20 09:54:53 +00:00
parent 7cbf1bcb3e
commit 57e7447c44
2 changed files with 35 additions and 2 deletions
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28
Lib/test/string_tests.py
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@ -114,6 +114,33 @@ def test_count(self):
self.checkraises(TypeError, 'hello', 'count') self.checkraises(TypeError, 'hello', 'count')
self.checkraises(TypeError, 'hello', 'count', 42) self.checkraises(TypeError, 'hello', 'count', 42)
# For a variety of combinations,
# verify that str.count() matches an equivalent function
# replacing all occurrences and then differencing the string lengths
charset = ['', 'a', 'b']
digits = 7
base = len(charset)
teststrings = set()
for i in xrange(base ** digits):
entry = []
for j in xrange(digits):
i, m = divmod(i, base)
entry.append(charset[m])
teststrings.add(''.join(entry))
teststrings = list(teststrings)
for i in teststrings:
i = self.fixtype(i)
n = len(i)
for j in teststrings:
r1 = i.count(j)
if j:
r2, rem = divmod(n - len(i.replace(j, '')), len(j))
else:
r2, rem = len(i)+1, 0
if rem or r1 != r2:
self.assertEqual(rem, 0)
self.assertEqual(r1, r2)
def test_find(self): def test_find(self):
self.checkequal(0, 'abcdefghiabc', 'find', 'abc') self.checkequal(0, 'abcdefghiabc', 'find', 'abc')
self.checkequal(9, 'abcdefghiabc', 'find', 'abc', 1) self.checkequal(9, 'abcdefghiabc', 'find', 'abc', 1)
@ -135,6 +162,7 @@ def test_find(self):
i, m = divmod(i, base) i, m = divmod(i, base)
entry.append(charset[m]) entry.append(charset[m])
teststrings.add(''.join(entry)) teststrings.add(''.join(entry))
teststrings = list(teststrings)
for i in teststrings: for i in teststrings:
i = self.fixtype(i) i = self.fixtype(i)
for j in teststrings: for j in teststrings:

9
Objects/stringobject.c
View file

@ -2145,7 +2145,7 @@ interpreted as in slice notation.");
static PyObject * static PyObject *
string_count(PyStringObject *self, PyObject *args) string_count(PyStringObject *self, PyObject *args)
{ {
const char *s = PyString_AS_STRING(self), *sub; const char *s = PyString_AS_STRING(self), *sub, *t;
int len = PyString_GET_SIZE(self), n; int len = PyString_GET_SIZE(self), n;
int i = 0, last = INT_MAX; int i = 0, last = INT_MAX;
int m, r; int m, r;
@ -2186,11 +2186,16 @@ string_count(PyStringObject *self, PyObject *args)
} else { } else {
i++; i++;
} }
if (i >= m)
break;
t = memchr(s+i, sub[0], m-i);
if (t == NULL)
break;
i = t - s;
} }
return PyInt_FromLong((long) r); return PyInt_FromLong((long) r);
} }
PyDoc_STRVAR(swapcase__doc__, PyDoc_STRVAR(swapcase__doc__,
"S.swapcase() -> string\n\ "S.swapcase() -> string\n\
\n\ \n\