cpython/Objects/stringlib/localeutil.h

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/* stringlib: locale related helpers implementation */
#include <locale.h>
#ifndef STRINGLIB_IS_UNICODE
# error "localeutil is specific to Unicode"
#endif
typedef struct {
const char *grouping;
char previous;
Py_ssize_t i; /* Where we're currently pointing in grouping. */
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} STRINGLIB(GroupGenerator);
static void
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STRINGLIB(GroupGenerator_init)(STRINGLIB(GroupGenerator) *self, const char *grouping)
{
self->grouping = grouping;
self->i = 0;
self->previous = 0;
}
/* Returns the next grouping, or 0 to signify end. */
static Py_ssize_t
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STRINGLIB(GroupGenerator_next)(STRINGLIB(GroupGenerator) *self)
{
/* Note that we don't really do much error checking here. If a
grouping string contains just CHAR_MAX, for example, then just
terminate the generator. That shouldn't happen, but at least we
fail gracefully. */
switch (self->grouping[self->i]) {
case 0:
return self->previous;
case CHAR_MAX:
/* Stop the generator. */
return 0;
default: {
char ch = self->grouping[self->i];
self->previous = ch;
self->i++;
return (Py_ssize_t)ch;
}
}
}
/* Fill in some digits, leading zeros, and thousands separator. All
are optional, depending on when we're called. */
static void
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STRINGLIB(fill)(STRINGLIB_CHAR **digits_end, STRINGLIB_CHAR **buffer_end,
Py_ssize_t n_chars, Py_ssize_t n_zeros, STRINGLIB_CHAR* thousands_sep,
Py_ssize_t thousands_sep_len)
{
Py_ssize_t i;
if (thousands_sep) {
*buffer_end -= thousands_sep_len;
/* Copy the thousands_sep chars into the buffer. */
memcpy(*buffer_end, thousands_sep,
thousands_sep_len * STRINGLIB_SIZEOF_CHAR);
}
*buffer_end -= n_chars;
*digits_end -= n_chars;
memcpy(*buffer_end, *digits_end, n_chars * sizeof(STRINGLIB_CHAR));
*buffer_end -= n_zeros;
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for (i = 0; i < n_zeros; i++)
(*buffer_end)[i] = '0';
}
/**
* InsertThousandsGrouping:
* @buffer: A pointer to the start of a string.
* @n_buffer: Number of characters in @buffer.
* @digits: A pointer to the digits we're reading from. If count
* is non-NULL, this is unused.
* @n_digits: The number of digits in the string, in which we want
* to put the grouping chars.
* @min_width: The minimum width of the digits in the output string.
* Output will be zero-padded on the left to fill.
* @grouping: see definition in localeconv().
* @thousands_sep: see definition in localeconv().
*
* There are 2 modes: counting and filling. If @buffer is NULL,
* we are in counting mode, else filling mode.
* If counting, the required buffer size is returned.
* If filling, we know the buffer will be large enough, so we don't
* need to pass in the buffer size.
* Inserts thousand grouping characters (as defined by grouping and
* thousands_sep) into the string between buffer and buffer+n_digits.
*
* 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.
*
* As closely as possible, this code mimics the logic in decimal.py's
_insert_thousands_sep().
**/
static Py_ssize_t
STRINGLIB(InsertThousandsGrouping)(
STRINGLIB_CHAR *buffer,
Py_ssize_t n_buffer,
STRINGLIB_CHAR *digits,
Py_ssize_t n_digits,
Py_ssize_t min_width,
const char *grouping,
STRINGLIB_CHAR *thousands_sep,
Py_ssize_t thousands_sep_len)
{
Py_ssize_t count = 0;
Py_ssize_t n_zeros;
int loop_broken = 0;
int use_separator = 0; /* First time through, don't append the
separator. They only go between
groups. */
STRINGLIB_CHAR *buffer_end = NULL;
STRINGLIB_CHAR *digits_end = NULL;
Py_ssize_t l;
Py_ssize_t n_chars;
Py_ssize_t remaining = n_digits; /* Number of chars remaining to
be looked at */
/* A generator that returns all of the grouping widths, until it
returns 0. */
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STRINGLIB(GroupGenerator) groupgen;
STRINGLIB(GroupGenerator_init)(&groupgen, grouping);
if (buffer) {
buffer_end = buffer + n_buffer;
digits_end = digits + n_digits;
}
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while ((l = STRINGLIB(GroupGenerator_next)(&groupgen)) > 0) {
l = Py_MIN(l, Py_MAX(Py_MAX(remaining, min_width), 1));
n_zeros = Py_MAX(0, l - remaining);
n_chars = Py_MAX(0, Py_MIN(remaining, l));
/* Use n_zero zero's and n_chars chars */
/* Count only, don't do anything. */
count += (use_separator ? thousands_sep_len : 0) + n_zeros + n_chars;
if (buffer) {
/* Copy into the output buffer. */
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STRINGLIB(fill)(&digits_end, &buffer_end, n_chars, n_zeros,
use_separator ? thousands_sep : NULL, thousands_sep_len);
}
/* Use a separator next time. */
use_separator = 1;
remaining -= n_chars;
min_width -= l;
if (remaining <= 0 && min_width <= 0) {
loop_broken = 1;
break;
}
min_width -= thousands_sep_len;
}
if (!loop_broken) {
/* We left the loop without using a break statement. */
l = Py_MAX(Py_MAX(remaining, min_width), 1);
n_zeros = Py_MAX(0, l - remaining);
n_chars = Py_MAX(0, Py_MIN(remaining, l));
/* Use n_zero zero's and n_chars chars */
count += (use_separator ? thousands_sep_len : 0) + n_zeros + n_chars;
if (buffer) {
/* Copy into the output buffer. */
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STRINGLIB(fill)(&digits_end, &buffer_end, n_chars, n_zeros,
use_separator ? thousands_sep : NULL, thousands_sep_len);
}
}
return count;
}