391 lines
11 KiB
C
391 lines
11 KiB
C
/* stringlib: split implementation */
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#ifndef STRINGLIB_FASTSEARCH_H
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#error must include "stringlib/fastsearch.h" before including this module
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#endif
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/* Overallocate the initial list to reduce the number of reallocs for small
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split sizes. Eg, "A A A A A A A A A A".split() (10 elements) has three
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resizes, to sizes 4, 8, then 16. Most observed string splits are for human
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text (roughly 11 words per line) and field delimited data (usually 1-10
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fields). For large strings the split algorithms are bandwidth limited
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so increasing the preallocation likely will not improve things.*/
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#define MAX_PREALLOC 12
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/* 5 splits gives 6 elements */
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#define PREALLOC_SIZE(maxsplit) \
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(maxsplit >= MAX_PREALLOC ? MAX_PREALLOC : maxsplit+1)
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#define SPLIT_APPEND(data, left, right) \
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sub = STRINGLIB_NEW((data) + (left), \
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(right) - (left)); \
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if (sub == NULL) \
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goto onError; \
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if (PyList_Append(list, sub)) { \
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Py_DECREF(sub); \
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goto onError; \
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} \
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else \
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Py_DECREF(sub);
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#define SPLIT_ADD(data, left, right) { \
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sub = STRINGLIB_NEW((data) + (left), \
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(right) - (left)); \
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if (sub == NULL) \
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goto onError; \
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if (count < MAX_PREALLOC) { \
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PyList_SET_ITEM(list, count, sub); \
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} else { \
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if (PyList_Append(list, sub)) { \
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Py_DECREF(sub); \
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goto onError; \
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} \
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else \
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Py_DECREF(sub); \
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} \
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count++; }
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/* Always force the list to the expected size. */
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#define FIX_PREALLOC_SIZE(list) Py_SET_SIZE(list, count)
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(split_whitespace)(PyObject* str_obj,
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const STRINGLIB_CHAR* str, Py_ssize_t str_len,
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Py_ssize_t maxcount)
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{
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Py_ssize_t i, j, count=0;
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PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
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PyObject *sub;
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if (list == NULL)
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return NULL;
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i = j = 0;
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while (maxcount-- > 0) {
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while (i < str_len && STRINGLIB_ISSPACE(str[i]))
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i++;
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if (i == str_len) break;
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j = i; i++;
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while (i < str_len && !STRINGLIB_ISSPACE(str[i]))
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i++;
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#ifndef STRINGLIB_MUTABLE
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if (j == 0 && i == str_len && STRINGLIB_CHECK_EXACT(str_obj)) {
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/* No whitespace in str_obj, so just use it as list[0] */
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Py_INCREF(str_obj);
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PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
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count++;
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break;
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}
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#endif
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SPLIT_ADD(str, j, i);
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}
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if (i < str_len) {
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/* Only occurs when maxcount was reached */
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/* Skip any remaining whitespace and copy to end of string */
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while (i < str_len && STRINGLIB_ISSPACE(str[i]))
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i++;
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if (i != str_len)
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SPLIT_ADD(str, i, str_len);
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}
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FIX_PREALLOC_SIZE(list);
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return list;
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onError:
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Py_DECREF(list);
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return NULL;
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}
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(split_char)(PyObject* str_obj,
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const STRINGLIB_CHAR* str, Py_ssize_t str_len,
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const STRINGLIB_CHAR ch,
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Py_ssize_t maxcount)
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{
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Py_ssize_t i, j, count=0;
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PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
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PyObject *sub;
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if (list == NULL)
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return NULL;
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i = j = 0;
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while ((j < str_len) && (maxcount-- > 0)) {
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for(; j < str_len; j++) {
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/* I found that using memchr makes no difference */
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if (str[j] == ch) {
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SPLIT_ADD(str, i, j);
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i = j = j + 1;
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break;
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}
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}
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}
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#ifndef STRINGLIB_MUTABLE
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if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
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/* ch not in str_obj, so just use str_obj as list[0] */
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Py_INCREF(str_obj);
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PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
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count++;
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} else
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#endif
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if (i <= str_len) {
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SPLIT_ADD(str, i, str_len);
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}
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FIX_PREALLOC_SIZE(list);
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return list;
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onError:
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Py_DECREF(list);
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return NULL;
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}
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(split)(PyObject* str_obj,
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const STRINGLIB_CHAR* str, Py_ssize_t str_len,
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const STRINGLIB_CHAR* sep, Py_ssize_t sep_len,
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Py_ssize_t maxcount)
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{
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Py_ssize_t i, j, pos, count=0;
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PyObject *list, *sub;
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if (sep_len == 0) {
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PyErr_SetString(PyExc_ValueError, "empty separator");
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return NULL;
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}
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else if (sep_len == 1)
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return STRINGLIB(split_char)(str_obj, str, str_len, sep[0], maxcount);
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list = PyList_New(PREALLOC_SIZE(maxcount));
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if (list == NULL)
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return NULL;
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i = j = 0;
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while (maxcount-- > 0) {
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pos = FASTSEARCH(str+i, str_len-i, sep, sep_len, -1, FAST_SEARCH);
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if (pos < 0)
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break;
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j = i + pos;
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SPLIT_ADD(str, i, j);
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i = j + sep_len;
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}
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#ifndef STRINGLIB_MUTABLE
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if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
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/* No match in str_obj, so just use it as list[0] */
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Py_INCREF(str_obj);
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PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
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count++;
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} else
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#endif
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{
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SPLIT_ADD(str, i, str_len);
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}
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FIX_PREALLOC_SIZE(list);
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return list;
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onError:
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Py_DECREF(list);
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return NULL;
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}
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(rsplit_whitespace)(PyObject* str_obj,
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const STRINGLIB_CHAR* str, Py_ssize_t str_len,
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Py_ssize_t maxcount)
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{
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Py_ssize_t i, j, count=0;
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PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
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PyObject *sub;
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if (list == NULL)
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return NULL;
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i = j = str_len - 1;
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while (maxcount-- > 0) {
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while (i >= 0 && STRINGLIB_ISSPACE(str[i]))
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i--;
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if (i < 0) break;
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j = i; i--;
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while (i >= 0 && !STRINGLIB_ISSPACE(str[i]))
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i--;
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#ifndef STRINGLIB_MUTABLE
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if (j == str_len - 1 && i < 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
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/* No whitespace in str_obj, so just use it as list[0] */
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Py_INCREF(str_obj);
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PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
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count++;
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break;
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}
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#endif
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SPLIT_ADD(str, i + 1, j + 1);
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}
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if (i >= 0) {
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/* Only occurs when maxcount was reached */
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/* Skip any remaining whitespace and copy to beginning of string */
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while (i >= 0 && STRINGLIB_ISSPACE(str[i]))
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i--;
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if (i >= 0)
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SPLIT_ADD(str, 0, i + 1);
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}
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FIX_PREALLOC_SIZE(list);
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if (PyList_Reverse(list) < 0)
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goto onError;
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return list;
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onError:
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Py_DECREF(list);
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return NULL;
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}
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(rsplit_char)(PyObject* str_obj,
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const STRINGLIB_CHAR* str, Py_ssize_t str_len,
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const STRINGLIB_CHAR ch,
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Py_ssize_t maxcount)
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{
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Py_ssize_t i, j, count=0;
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PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));
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PyObject *sub;
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if (list == NULL)
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return NULL;
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i = j = str_len - 1;
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while ((i >= 0) && (maxcount-- > 0)) {
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for(; i >= 0; i--) {
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if (str[i] == ch) {
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SPLIT_ADD(str, i + 1, j + 1);
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j = i = i - 1;
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break;
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}
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}
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}
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#ifndef STRINGLIB_MUTABLE
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if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
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/* ch not in str_obj, so just use str_obj as list[0] */
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Py_INCREF(str_obj);
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PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
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count++;
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} else
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#endif
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if (j >= -1) {
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SPLIT_ADD(str, 0, j + 1);
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}
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FIX_PREALLOC_SIZE(list);
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if (PyList_Reverse(list) < 0)
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goto onError;
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return list;
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onError:
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Py_DECREF(list);
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return NULL;
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}
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(rsplit)(PyObject* str_obj,
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const STRINGLIB_CHAR* str, Py_ssize_t str_len,
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const STRINGLIB_CHAR* sep, Py_ssize_t sep_len,
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Py_ssize_t maxcount)
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{
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Py_ssize_t j, pos, count=0;
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PyObject *list, *sub;
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if (sep_len == 0) {
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PyErr_SetString(PyExc_ValueError, "empty separator");
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return NULL;
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}
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else if (sep_len == 1)
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return STRINGLIB(rsplit_char)(str_obj, str, str_len, sep[0], maxcount);
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list = PyList_New(PREALLOC_SIZE(maxcount));
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if (list == NULL)
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return NULL;
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j = str_len;
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while (maxcount-- > 0) {
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pos = FASTSEARCH(str, j, sep, sep_len, -1, FAST_RSEARCH);
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if (pos < 0)
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break;
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SPLIT_ADD(str, pos + sep_len, j);
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j = pos;
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}
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#ifndef STRINGLIB_MUTABLE
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if (count == 0 && STRINGLIB_CHECK_EXACT(str_obj)) {
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/* No match in str_obj, so just use it as list[0] */
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Py_INCREF(str_obj);
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PyList_SET_ITEM(list, 0, (PyObject *)str_obj);
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count++;
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} else
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#endif
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{
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SPLIT_ADD(str, 0, j);
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}
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FIX_PREALLOC_SIZE(list);
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if (PyList_Reverse(list) < 0)
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goto onError;
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return list;
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onError:
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Py_DECREF(list);
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return NULL;
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}
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(splitlines)(PyObject* str_obj,
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const STRINGLIB_CHAR* str, Py_ssize_t str_len,
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int keepends)
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{
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/* This does not use the preallocated list because splitlines is
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usually run with hundreds of newlines. The overhead of
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switching between PyList_SET_ITEM and append causes about a
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2-3% slowdown for that common case. A smarter implementation
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could move the if check out, so the SET_ITEMs are done first
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and the appends only done when the prealloc buffer is full.
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That's too much work for little gain.*/
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Py_ssize_t i;
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Py_ssize_t j;
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PyObject *list = PyList_New(0);
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PyObject *sub;
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if (list == NULL)
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return NULL;
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for (i = j = 0; i < str_len; ) {
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Py_ssize_t eol;
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/* Find a line and append it */
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while (i < str_len && !STRINGLIB_ISLINEBREAK(str[i]))
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i++;
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/* Skip the line break reading CRLF as one line break */
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eol = i;
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if (i < str_len) {
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if (str[i] == '\r' && i + 1 < str_len && str[i+1] == '\n')
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i += 2;
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else
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i++;
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if (keepends)
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eol = i;
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}
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#ifndef STRINGLIB_MUTABLE
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if (j == 0 && eol == str_len && STRINGLIB_CHECK_EXACT(str_obj)) {
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/* No linebreak in str_obj, so just use it as list[0] */
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if (PyList_Append(list, str_obj))
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goto onError;
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break;
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}
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#endif
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SPLIT_APPEND(str, j, eol);
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j = i;
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}
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return list;
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onError:
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Py_DECREF(list);
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return NULL;
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}
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