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_astrcmp: Operate on a UCS4 copy of strings

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Ensures thread safety of the LevenshteinDistance call
This commit is contained in:
Philipp Wolfer
2018-10-19 00:01:09 +02:00
parent 69a64bad64
commit beceaf964b
1 changed files with 14 additions and 18 deletions
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32
picard/util/_astrcmp.c
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@@ -57,8 +57,8 @@
#define MAX(x, y) (((x) > (y)) ? (x) : (y))
#define MATRIX(a, b) matrix[(b) * (len1 + 1) + (a)]
float LevenshteinDistance(int k1, const void * s1, Py_ssize_t len1,
int k2, const void * s2, Py_ssize_t len2)
float LevenshteinDistance(const Py_UCS4 * s1, Py_ssize_t len1,
const Py_UCS4 * s2, Py_ssize_t len2)
{
int *matrix, index1, index2;
float result;
@@ -88,16 +88,14 @@ float LevenshteinDistance(int k1, const void * s1, Py_ssize_t len1,
for (index1 = 1; index1 <= len1; index1++)
{
Py_UCS4 s1_previous = 0;
Py_UCS4 s1_current = PyUnicode_READ(k1, s1, index1 - 1);
Py_UCS4 s1_current = s1[index1 - 1];
/* Step 4 */
/* Loop through second string */
for (index2 = 1; index2 <= len2; index2++)
{
Py_UCS4 s2_previous = 0;
Py_UCS4 s2_current = PyUnicode_READ(k2, s2, index2 - 1);
Py_UCS4 s2_current = s2[index2 - 1];
/* Step 5 */
/* Calculate cost of this iteration
@@ -122,19 +120,16 @@ float LevenshteinDistance(int k1, const void * s1, Py_ssize_t len1,
if (index1 > 2 && index2 > 2)
{
int trans = MATRIX(index1 - 2, index2 - 2) + 1;
if (s1_previous != s2_current)
if (s1[index1 - 2] != s2_current)
trans++;
if (s1_current != s2_previous)
if (s1_current != s2[index2 - 2])
trans++;
if (cell > trans)
cell = trans;
}
MATRIX(index1, index2) = cell;
s2_previous = s2_current;
}
s1_previous = s1_current;
}
@@ -153,8 +148,7 @@ astrcmp(PyObject *self, PyObject *args)
{
PyObject *s1, *s2;
float d;
const void *ud1, *ud2;
int k1, k2;
Py_UCS4 *us1, *us2;
Py_ssize_t len1, len2;
PyThreadState *_save;
@@ -164,16 +158,18 @@ astrcmp(PyObject *self, PyObject *args)
if (PyUnicode_READY(s1) == -1 || PyUnicode_READY(s2) == -1)
return NULL;
k1 = PyUnicode_KIND(s1);
k2 = PyUnicode_KIND(s2);
ud1 = PyUnicode_DATA(s1);
ud2 = PyUnicode_DATA(s2);
len1 = PyUnicode_GetLength(s1);
len2 = PyUnicode_GetLength(s2);
us1 = PyUnicode_AsUCS4Copy(s1);
us2 = PyUnicode_AsUCS4Copy(s2);
Py_UNBLOCK_THREADS
d = LevenshteinDistance(k1, ud1, len1, k2, ud2, len2);
d = LevenshteinDistance(us1, len1, us2, len2);
Py_BLOCK_THREADS
PyMem_Free(us1);
PyMem_Free(us2);
return Py_BuildValue("f", d);
}