diff options
| -rw-r--r-- | src/pooptmodule.c | 58 |
1 files changed, 58 insertions, 0 deletions
diff --git a/src/pooptmodule.c b/src/pooptmodule.c index f6840abd..b80bc8dc 100644 --- a/src/pooptmodule.c +++ b/src/pooptmodule.c @@ -207,6 +207,63 @@ static PyObject* poopt_wcswidth(PyObject* self, PyObject* args) return Py_BuildValue("i", res); } +/** + cut_by_columns: takes a python string and a number of columns, returns a + python string truncated to take at most that many columns + For example cut_by_columns(n, "エメルカ") will return: + - n == 5 -> "エメ" (which takes only 4 columns since we can't cut the next character in half) + - n == 2 -> "エ" + - n == 1 -> "" + - n == 42 -> "エメルカ" + - etc +*/ +PyDoc_STRVAR(poopt_cut_by_columns_doc, "cut_by_columns(n, string)\n\n\nreturns a string truncated to take at most n columns"); +static PyObject* poopt_cut_by_columns(PyObject* self, PyObject* args) +{ + const char* start; + const size_t len; + const size_t limit; + if (PyArg_ParseTuple(args, "Is#", &limit, &start, &len) == 0) + return NULL; + + const char* const end = start + len; + const char* ptr = start; + wchar_t wc; + + /* The number of columns that the string would take so far */ + size_t columns = 0; + + while (ptr < end) + { + const size_t consumed = mbrtowc(&wc, ptr, end-ptr, NULL); + if (consumed == 0) + break ; + else if ((size_t)-1 == consumed) + { + PyErr_SetString(PyExc_UnicodeError, + "mbrtowc returned -1: Invalid multibyte sequence."); + return NULL; + } + else if ((size_t)-2 == consumed) + { + PyErr_SetString(PyExc_UnicodeError, + "mbrtowc returned -2: Could not parse a complete multibyte character."); + return NULL; + } + const size_t cols = wcwidth(wc); + if (columns + cols > limit) + /* Adding the next character would exceed the column limit */ + break ; + ptr += consumed; + columns += cols; + if (columns == limit) + /* With the new character we are exactly at the column limit. No + need to go check the next char */ + break ; + } + return Py_BuildValue("s#", start, ptr - start); +} + /*** Module initialization. Just taken from the xxmodule.c template from the python sources. ***/ @@ -310,6 +367,7 @@ static PyTypeObject Null_Type = { static PyMethodDef poopt_methods[] = { {"cut_text", poopt_cut_text, METH_VARARGS, poopt_cut_text_doc}, {"wcswidth", poopt_wcswidth, METH_VARARGS, poopt_wcswidth_doc}, + {"cut_by_columns", poopt_cut_by_columns, METH_VARARGS, poopt_cut_by_columns_doc}, {} /* sentinel */ }; |