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  r64984 | eric.smith | 2008-07-15 20:11:49 -0400 (Tue, 15 Jul 2008) | 1 line

  Complete issue 3083: add alternate (#) formatting to bin, oct, hex in str.format().
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ericvsmith committed Jul 16, 2008
1 parent f70e195 commit d68af8f
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8 changes: 6 additions & 2 deletions Doc/library/string.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -294,7 +294,7 @@ result as if you had called :func:`str` on the value.
The general form of a *standard format specifier* is:

.. productionlist:: sf
format_spec: [[`fill`]`align`][`sign`][0][`width`][.`precision`][`type`]
format_spec: [[`fill`]`align`][`sign`][#][0][`width`][.`precision`][`type`]
fill: <a character other than '}'>
align: "<" | ">" | "=" | "^"
sign: "+" | "-" | " "
Expand Down Expand Up @@ -348,6 +348,10 @@ following:
| | positive numbers, and a minus sign on negative numbers. |
+---------+----------------------------------------------------------+

The ``'#'`` option is only valid for integers, and only for binary,
octal, or decimal output. If present, it specifies that the output
will be prefixed by ``'0b'``, ``'0o'``, or ``'0x'``, respectively.

*width* is a decimal integer defining the minimum field width. If not
specified, then the field width will be determined by the content.

Expand All @@ -368,7 +372,7 @@ The available integer presentation types are:
+---------+----------------------------------------------------------+
| Type | Meaning |
+=========+==========================================================+
| ``'b'`` | Binary. Outputs the number in base 2. |
| ``'b'`` | Binary format. Outputs the number in base 2. |
+---------+----------------------------------------------------------+
| ``'c'`` | Character. Converts the integer to the corresponding |
| | unicode character before printing. |
Expand Down
13 changes: 12 additions & 1 deletion Lib/test/test_types.py
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Original file line number Diff line number Diff line change
Expand Up @@ -301,7 +301,8 @@ def test(i, format_spec, result):
test(-1, "-#5b", ' -0b1')
test(1, "+#5b", ' +0b1')
test(100, "+#b", '+0b1100100')
# test(100, "#012b", '0b001100100')
test(100, "#012b", '0b0001100100')
test(-100, "#012b", '-0b001100100')

test(0, "#o", '0o0')
test(0, "-#o", '0o0')
Expand All @@ -310,6 +311,8 @@ def test(i, format_spec, result):
test(-1, "-#5o", ' -0o1')
test(1, "+#5o", ' +0o1')
test(100, "+#o", '+0o144')
test(100, "#012o", '0o0000000144')
test(-100, "#012o", '-0o000000144')

test(0, "#x", '0x0')
test(0, "-#x", '0x0')
Expand All @@ -318,6 +321,10 @@ def test(i, format_spec, result):
test(-1, "-#5x", ' -0x1')
test(1, "+#5x", ' +0x1')
test(100, "+#x", '+0x64')
test(100, "#012x", '0x0000000064')
test(-100, "#012x", '-0x000000064')
test(123456, "#012x", '0x000001e240')
test(-123456, "#012x", '-0x00001e240')

test(0, "#X", '0X0')
test(0, "-#X", '0X0')
Expand All @@ -326,6 +333,10 @@ def test(i, format_spec, result):
test(-1, "-#5X", ' -0X1')
test(1, "+#5X", ' +0X1')
test(100, "+#X", '+0X64')
test(100, "#012X", '0X0000000064')
test(-100, "#012X", '-0X000000064')
test(123456, "#012X", '0X000001E240')
test(-123456, "#012X", '-0X00001E240')

# make sure these are errors

Expand Down
3 changes: 3 additions & 0 deletions Misc/NEWS
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,9 @@ What's new in Python 3.0b2?
Core and Builtins
-----------------

- Issue #3083: Add alternate (#) formatting for bin, oct, hex output
for str.format(). This adds the prefix 0b, 0o, or 0x, respectively.

- Issue #3280: like chr(), the "%c" format now accepts unicode code points
beyond the Basic Multilingual Plane (above 0xffff) on all configurations. On
"narrow Unicode" builds, the result is a string of 2 code units, forming a
Expand Down
98 changes: 68 additions & 30 deletions Objects/stringlib/formatter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -147,6 +147,13 @@ parse_internal_render_format_spec(STRINGLIB_CHAR *format_spec,
#endif
}

/* If the next character is #, we're in alternate mode. This only
applies to integers. */
if (end-ptr >= 1 && ptr[0] == '#') {
format->alternate = 1;
++ptr;
}

/* The special case for 0-padding (backwards compat) */
if (format->fill_char == '\0' && end-ptr >= 1 && ptr[0] == '0') {
format->fill_char = '0';
Expand All @@ -156,13 +163,6 @@ parse_internal_render_format_spec(STRINGLIB_CHAR *format_spec,
++ptr;
}

/* If the next character is #, we're in alternate mode. This only
applies to integers. */
if (end-ptr >= 1 && ptr[0] == '#') {
format->alternate = 1;
++ptr;
}

/* XXX add error checking */
specified_width = get_integer(&ptr, end, &format->width);

Expand Down Expand Up @@ -211,9 +211,10 @@ parse_internal_render_format_spec(STRINGLIB_CHAR *format_spec,
/************************************************************************/

/* describes the layout for an integer, see the comment in
_calc_integer_widths() for details */
calc_number_widths() for details */
typedef struct {
Py_ssize_t n_lpadding;
Py_ssize_t n_prefix;
Py_ssize_t n_spadding;
Py_ssize_t n_rpadding;
char lsign;
Expand All @@ -234,6 +235,7 @@ calc_number_widths(NumberFieldWidths *r, STRINGLIB_CHAR actual_sign,
const InternalFormatSpec *format)
{
r->n_lpadding = 0;
r->n_prefix = 0;
r->n_spadding = 0;
r->n_rpadding = 0;
r->lsign = '\0';
Expand Down Expand Up @@ -288,21 +290,25 @@ calc_number_widths(NumberFieldWidths *r, STRINGLIB_CHAR actual_sign,
}
}

r->n_prefix = n_prefix;

/* now the number of padding characters */
if (format->width == -1) {
/* no padding at all, nothing to do */
}
else {
/* see if any padding is needed */
if (r->n_lsign + n_digits + r->n_rsign >= format->width) {
if (r->n_lsign + n_digits + r->n_rsign +
r->n_prefix >= format->width) {
/* no padding needed, we're already bigger than the
requested width */
}
else {
/* determine which of left, space, or right padding is
needed */
Py_ssize_t padding = format->width -
(r->n_lsign + n_digits + r->n_rsign);
(r->n_lsign + r->n_prefix +
n_digits + r->n_rsign);
if (format->align == '<')
r->n_rpadding = padding;
else if (format->align == '>')
Expand All @@ -317,18 +323,19 @@ calc_number_widths(NumberFieldWidths *r, STRINGLIB_CHAR actual_sign,
r->n_lpadding = padding;
}
}
r->n_total = r->n_lpadding + r->n_lsign + r->n_spadding +
n_digits + r->n_rsign + r->n_rpadding;
r->n_total = r->n_lpadding + r->n_lsign + r->n_prefix +
r->n_spadding + n_digits + r->n_rsign + r->n_rpadding;
}

/* fill in the non-digit parts of a numbers's string representation,
as determined in _calc_integer_widths(). returns the pointer to
as determined in calc_number_widths(). returns the pointer to
where the digits go. */
static STRINGLIB_CHAR *
fill_non_digits(STRINGLIB_CHAR *p_buf, const NumberFieldWidths *spec,
Py_ssize_t n_digits, STRINGLIB_CHAR fill_char)
STRINGLIB_CHAR *prefix, Py_ssize_t n_digits,
STRINGLIB_CHAR fill_char)
{
STRINGLIB_CHAR* p_digits;
STRINGLIB_CHAR *p_digits;

if (spec->n_lpadding) {
STRINGLIB_FILL(p_buf, fill_char, spec->n_lpadding);
Expand All @@ -337,6 +344,12 @@ fill_non_digits(STRINGLIB_CHAR *p_buf, const NumberFieldWidths *spec,
if (spec->n_lsign == 1) {
*p_buf++ = spec->lsign;
}
if (spec->n_prefix) {
memmove(p_buf,
prefix,
spec->n_prefix * sizeof(STRINGLIB_CHAR));
p_buf += spec->n_prefix;
}
if (spec->n_spadding) {
STRINGLIB_FILL(p_buf, fill_char, spec->n_spadding);
p_buf += spec->n_spadding;
Expand Down Expand Up @@ -477,6 +490,8 @@ format_int_or_long_internal(PyObject *value, const InternalFormatSpec *format,
Py_ssize_t n_grouping_chars = 0; /* Count of additional chars to
allocate, used for 'n'
formatting. */
Py_ssize_t n_prefix = 0; /* Count of prefix chars, (e.g., '0x') */
STRINGLIB_CHAR *prefix = NULL;
NumberFieldWidths spec;
long x;

Expand Down Expand Up @@ -534,19 +549,16 @@ format_int_or_long_internal(PyObject *value, const InternalFormatSpec *format,
switch (format->type) {
case 'b':
base = 2;
if (!format->alternate)
leading_chars_to_skip = 2; /* 0b */
leading_chars_to_skip = 2; /* 0b */
break;
case 'o':
base = 8;
if (!format->alternate)
leading_chars_to_skip = 2; /* 0o */
leading_chars_to_skip = 2; /* 0o */
break;
case 'x':
case 'X':
base = 16;
if (!format->alternate)
leading_chars_to_skip = 2; /* 0x */
leading_chars_to_skip = 2; /* 0x */
break;
default: /* shouldn't be needed, but stops a compiler warning */
case 'd':
Expand All @@ -555,6 +567,11 @@ format_int_or_long_internal(PyObject *value, const InternalFormatSpec *format,
break;
}

/* The number of prefix chars is the same as the leading
chars to skip */
if (format->alternate)
n_prefix = leading_chars_to_skip;

/* Do the hard part, converting to a string in a given base */
tmp = tostring(value, base);
if (tmp == NULL)
Expand All @@ -563,6 +580,8 @@ format_int_or_long_internal(PyObject *value, const InternalFormatSpec *format,
pnumeric_chars = STRINGLIB_STR(tmp);
n_digits = STRINGLIB_LEN(tmp);

prefix = pnumeric_chars;

/* Remember not to modify what pnumeric_chars points to. it
might be interned. Only modify it after we copy it into a
newly allocated output buffer. */
Expand All @@ -571,6 +590,7 @@ format_int_or_long_internal(PyObject *value, const InternalFormatSpec *format,
and skip it */
sign = pnumeric_chars[0];
if (sign == '-') {
++prefix;
++leading_chars_to_skip;
}

Expand All @@ -586,43 +606,61 @@ format_int_or_long_internal(PyObject *value, const InternalFormatSpec *format,
0, &n_grouping_chars, 0);

/* Calculate the widths of the various leading and trailing parts */
calc_number_widths(&spec, sign, 0, n_digits + n_grouping_chars, format);
calc_number_widths(&spec, sign, n_prefix, n_digits + n_grouping_chars,
format);

/* Allocate a new string to hold the result */
result = STRINGLIB_NEW(NULL, spec.n_total);
if (!result)
goto done;
p = STRINGLIB_STR(result);

/* XXX There is too much magic here regarding the internals of
spec and the location of the prefix and digits. It would be
better if calc_number_widths returned a number of logical
offsets into the buffer, and those were used. Maybe in a
future code cleanup. */

/* Fill in the digit parts */
n_leading_chars = spec.n_lpadding + spec.n_lsign + spec.n_spadding;
n_leading_chars = spec.n_lpadding + spec.n_lsign +
spec.n_prefix + spec.n_spadding;
memmove(p + n_leading_chars,
pnumeric_chars,
n_digits * sizeof(STRINGLIB_CHAR));

/* If type is 'X', convert to uppercase */
/* If type is 'X', convert the filled in digits to uppercase */
if (format->type == 'X') {
Py_ssize_t t;
for (t = 0; t < n_digits; ++t)
p[t + n_leading_chars] = STRINGLIB_TOUPPER(p[t + n_leading_chars]);
}

/* Insert the grouping, if any, after the uppercasing of 'X', so we can
ensure that grouping chars won't be affected. */
/* Insert the grouping, if any, after the uppercasing of the digits, so
we can ensure that grouping chars won't be affected. */
if (n_grouping_chars) {
/* We know this can't fail, since we've already
reserved enough space. */
STRINGLIB_CHAR *pstart = p + n_leading_chars;
int r = STRINGLIB_GROUPING(pstart, n_digits, n_digits,
spec.n_total+n_grouping_chars-n_leading_chars,
NULL, 0);
spec.n_total+n_grouping_chars-n_leading_chars,
NULL, 0);
assert(r);
}

/* Fill in the non-digit parts (padding, sign, etc.) */
fill_non_digits(p, &spec, n_digits + n_grouping_chars,
fill_non_digits(p, &spec, prefix, n_digits + n_grouping_chars,
format->fill_char == '\0' ? ' ' : format->fill_char);

/* If type is 'X', uppercase the prefix. This has to be done after the
prefix is filled in by fill_non_digits */
if (format->type == 'X') {
Py_ssize_t t;
for (t = 0; t < n_prefix; ++t)
p[t + spec.n_lpadding + spec.n_lsign] =
STRINGLIB_TOUPPER(p[t + spec.n_lpadding + spec.n_lsign]);
}


done:
Py_XDECREF(tmp);
return result;
Expand Down Expand Up @@ -768,7 +806,7 @@ format_float_internal(PyObject *value,
goto done;

/* Fill in the non-digit parts (padding, sign, etc.) */
fill_non_digits(STRINGLIB_STR(result), &spec, n_digits,
fill_non_digits(STRINGLIB_STR(result), &spec, NULL, n_digits,
format->fill_char == '\0' ? ' ' : format->fill_char);

/* fill in the digit parts */
Expand Down

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