mirror of https://github.com/python/cpython
134 lines
3.5 KiB
C
134 lines
3.5 KiB
C
/* stringlib: bytes joining implementation */
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#if STRINGLIB_SIZEOF_CHAR != 1
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#error join.h only compatible with byte-wise strings
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#endif
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Py_LOCAL_INLINE(PyObject *)
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STRINGLIB(bytes_join)(PyObject *sep, PyObject *iterable)
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{
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char *sepstr = STRINGLIB_STR(sep);
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const Py_ssize_t seplen = STRINGLIB_LEN(sep);
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PyObject *res = NULL;
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char *p;
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Py_ssize_t seqlen = 0;
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Py_ssize_t sz = 0;
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Py_ssize_t i, nbufs;
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PyObject *seq, *item;
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Py_buffer *buffers = NULL;
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#define NB_STATIC_BUFFERS 10
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Py_buffer static_buffers[NB_STATIC_BUFFERS];
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seq = PySequence_Fast(iterable, "can only join an iterable");
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if (seq == NULL) {
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return NULL;
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}
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seqlen = PySequence_Fast_GET_SIZE(seq);
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if (seqlen == 0) {
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Py_DECREF(seq);
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return STRINGLIB_NEW(NULL, 0);
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}
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#ifndef STRINGLIB_MUTABLE
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if (seqlen == 1) {
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item = PySequence_Fast_GET_ITEM(seq, 0);
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if (STRINGLIB_CHECK_EXACT(item)) {
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Py_INCREF(item);
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Py_DECREF(seq);
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return item;
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}
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}
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#endif
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if (seqlen > NB_STATIC_BUFFERS) {
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buffers = PyMem_NEW(Py_buffer, seqlen);
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if (buffers == NULL) {
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Py_DECREF(seq);
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PyErr_NoMemory();
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return NULL;
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}
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}
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else {
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buffers = static_buffers;
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}
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/* Here is the general case. Do a pre-pass to figure out the total
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* amount of space we'll need (sz), and see whether all arguments are
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* bytes-like.
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*/
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for (i = 0, nbufs = 0; i < seqlen; i++) {
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Py_ssize_t itemlen;
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item = PySequence_Fast_GET_ITEM(seq, i);
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if (_getbuffer(item, &buffers[i]) < 0) {
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PyErr_Format(PyExc_TypeError,
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"sequence item %zd: expected a bytes-like object, "
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"%.80s found",
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i, Py_TYPE(item)->tp_name);
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goto error;
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}
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nbufs = i + 1; /* for error cleanup */
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itemlen = buffers[i].len;
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if (itemlen > PY_SSIZE_T_MAX - sz) {
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PyErr_SetString(PyExc_OverflowError,
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"join() result is too long");
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goto error;
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}
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sz += itemlen;
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if (i != 0) {
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if (seplen > PY_SSIZE_T_MAX - sz) {
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PyErr_SetString(PyExc_OverflowError,
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"join() result is too long");
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goto error;
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}
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sz += seplen;
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}
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if (seqlen != PySequence_Fast_GET_SIZE(seq)) {
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PyErr_SetString(PyExc_RuntimeError,
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"sequence changed size during iteration");
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goto error;
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}
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}
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/* Allocate result space. */
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res = STRINGLIB_NEW(NULL, sz);
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if (res == NULL)
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goto error;
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/* Catenate everything. */
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p = STRINGLIB_STR(res);
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if (!seplen) {
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/* fast path */
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for (i = 0; i < nbufs; i++) {
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Py_ssize_t n = buffers[i].len;
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char *q = buffers[i].buf;
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Py_MEMCPY(p, q, n);
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p += n;
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}
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goto done;
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}
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for (i = 0; i < nbufs; i++) {
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Py_ssize_t n;
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char *q;
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if (i) {
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Py_MEMCPY(p, sepstr, seplen);
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p += seplen;
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}
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n = buffers[i].len;
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q = buffers[i].buf;
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Py_MEMCPY(p, q, n);
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p += n;
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}
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goto done;
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error:
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res = NULL;
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done:
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Py_DECREF(seq);
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for (i = 0; i < nbufs; i++)
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PyBuffer_Release(&buffers[i]);
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if (buffers != static_buffers)
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PyMem_FREE(buffers);
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return res;
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}
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#undef NB_STATIC_BUFFERS
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