cpython/Objects/stringlib/localeutil.h

/* stringlib: locale related helpers implementation */

#ifndef STRINGLIB_LOCALEUTIL_H
#define STRINGLIB_LOCALEUTIL_H

#include <locale.h>

/**
 * _Py_InsertThousandsGrouping:
 * @buffer: A pointer to the start of a string.
 * @n_buffer: The length of the string.
 * @n_digits: The number of digits in the string, in which we want
 *            to put the grouping chars.
 * @buf_size: The maximum size of the buffer pointed to by buffer.
 * @count: If non-NULL, points to a variable that will receive the
 *         number of characters we need to insert (and no formatting
 *         will actually occur).
 * @append_zero_char: If non-zero, put a trailing zero at the end of
 *         of the resulting string, if and only if we modified the
 *         string.
 * @grouping: see definition in localeconv().
 * @thousands_sep: see definition in localeconv().
 *
 * Inserts thousand grouping characters (as defined by grouping and
 *  thousands_sep) into the string between buffer and buffer+n_digits.
 *  If count is non-NULL, don't do any formatting, just count the
 *  number of characters to insert.  This is used by the caller to
 *  appropriately resize the buffer, if needed.  If count is non-NULL,
 *  buffer can be NULL (it is not dereferenced at all in that case).
 *
 * Return value: 0 on error, else 1.  Note that no error can occur if
 *  count is non-NULL.
 *
 * This name won't be used, the includer of this file should define
 *  it to be the actual function name, based on unicode or string.
 **/
int
_Py_InsertThousandsGrouping(STRINGLIB_CHAR *buffer,
                            Py_ssize_t n_buffer,
                            Py_ssize_t n_digits,
                            Py_ssize_t buf_size,
                            Py_ssize_t *count,
                            int append_zero_char,
                            const char *grouping,
                            const char *thousands_sep)
{
        Py_ssize_t thousands_sep_len = strlen(thousands_sep);
        STRINGLIB_CHAR *pend = NULL; /* current end of buffer */
        STRINGLIB_CHAR *pmax = NULL; /* max of buffer */
        char current_grouping;
        Py_ssize_t remaining = n_digits; /* Number of chars remaining to
                                            be looked at */

        /* Initialize the character count, if we're just counting. */
        if (count)
                *count = 0;
        else {
                /* We're not just counting, we're modifying buffer */
                pend = buffer + n_buffer;
                pmax = buffer + buf_size;
        }

        /* Starting at the end and working right-to-left, keep track of
           what grouping needs to be added and insert that. */
        current_grouping = *grouping++;

        /* If the first character is 0, perform no grouping at all. */
        if (current_grouping == 0)
                return 1;

        while (remaining > current_grouping) {
                /* Always leave buffer and pend valid at the end of this
                   loop, since we might leave with a return statement. */

                remaining -= current_grouping;
                if (count) {
                        /* We're only counting, not touching the memory. */
                        *count += thousands_sep_len;
                }
                else {
                        /* Do the formatting. */

                        STRINGLIB_CHAR *plast = buffer + remaining;

                        /* Is there room to insert thousands_sep_len chars? */
                        if (pmax - pend < thousands_sep_len)
                                /* No room. */
                                return 0;

                        /* Move the rest of the string down. */
                        memmove(plast + thousands_sep_len,
                                plast,
                                (pend - plast) * sizeof(STRINGLIB_CHAR));
                        /* Copy the thousands_sep chars into the buffer. */
#if STRINGLIB_IS_UNICODE
                        /* Convert from the char's of the thousands_sep from
                           the locale into unicode. */
                        {
                                Py_ssize_t i;
                                for (i = 0; i < thousands_sep_len; ++i)
                                        plast[i] = thousands_sep[i];
                        }
#else
                        /* No conversion, just memcpy the thousands_sep. */
                        memcpy(plast, thousands_sep, thousands_sep_len);
#endif
                }

                /* Adjust end pointer. */
                pend += thousands_sep_len;

                /* Move to the next grouping character, unless we're
                   repeating (which is designated by a grouping of 0). */
                if (*grouping != 0) {
                        current_grouping = *grouping++;
                        if (current_grouping == CHAR_MAX)
                                /* We're done. */
                                break;
                }
        }
        if (append_zero_char) {
                /* Append a zero character to mark the end of the string,
                   if there's room. */
                if (pend - (buffer + remaining) < 1)
                        /* No room, error. */
                        return 0;
                *pend = 0;
        }
        return 1;
}

/**
 * _Py_InsertThousandsGroupingLocale:
 * @buffer: A pointer to the start of a string.
 * @n_buffer: The length of the string.
 * @n_digits: The number of digits in the string, in which we want
 *            to put the grouping chars.
 * @buf_size: The maximum size of the buffer pointed to by buffer.
 * @count: If non-NULL, points to a variable that will receive the
 *         number of characters we need to insert (and no formatting
 *         will actually occur).
 * @append_zero_char: If non-zero, put a trailing zero at the end of
 *         of the resulting string, if and only if we modified the
 *         string.
 *
 * Reads thee current locale and calls _Py_InsertThousandsGrouping().
 **/
int
_Py_InsertThousandsGroupingLocale(STRINGLIB_CHAR *buffer,
                                  Py_ssize_t n_buffer,
                                  Py_ssize_t n_digits,
                                  Py_ssize_t buf_size,
                                  Py_ssize_t *count,
                                  int append_zero_char)
{
        struct lconv *locale_data = localeconv();
        const char *grouping = locale_data->grouping;
        const char *thousands_sep = locale_data->thousands_sep;

        return _Py_InsertThousandsGrouping(buffer, n_buffer, n_digits,
                                           buf_size, count,
                                           append_zero_char, grouping,
                                           thousands_sep);
}
#endif /* STRINGLIB_LOCALEUTIL_H */