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cpython/Objects/stringlib/string_format.h
Eric Smith 625cbf28ee Modified parsing of format strings, so that we always return 
a tuple (literal, field_name, format_spec, conversion).

literal will always be a string, but might be of zero length.
field_name will be None if there is no markup text
format_spec will be a (possibly zero length) string if
  field_name is non-None
conversion will be a one character string, or None

This makes the Formatter class, and especially it's parse()
method, easier to understand.

Suggestion was by Jim Jewett, inspired by the "tail" of an
elementtree node.

Also, fixed a reference leak in fieldnameiter_next.
2007-08-29 03:22:59 +00:00

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/*
string_format.h -- implementation of string.format().
It uses the Objects/stringlib conventions, so that it can be
compiled for both unicode and string objects.
*/
/* Defines for more efficiently reallocating the string buffer */
#define INITIAL_SIZE_INCREMENT 100
#define SIZE_MULTIPLIER 2
#define MAX_SIZE_INCREMENT 3200
/************************************************************************/
/*********** Global data structures and forward declarations *********/
/************************************************************************/
/*
A SubString consists of the characters between two string or
unicode pointers.
*/
typedef struct {
STRINGLIB_CHAR *ptr;
STRINGLIB_CHAR *end;
} SubString;
/* forward declaration for recursion */
static PyObject *
build_string(SubString *input, PyObject *args, PyObject *kwargs,
int *recursion_level);
/************************************************************************/
/************************** Utility functions ************************/
/************************************************************************/
/* fill in a SubString from a pointer and length */
Py_LOCAL_INLINE(void)
SubString_init(SubString *str, STRINGLIB_CHAR *p, Py_ssize_t len)
{
str->ptr = p;
if (p == NULL)
str->end = NULL;
else
str->end = str->ptr + len;
}
/* return a new string. if str->ptr is NULL, return None */
Py_LOCAL_INLINE(PyObject *)
SubString_new_object(SubString *str)
{
if (str->ptr == NULL) {
Py_INCREF(Py_None);
return Py_None;
}
return STRINGLIB_NEW(str->ptr, str->end - str->ptr);
}
/* return a new string. if str->ptr is NULL, return None */
Py_LOCAL_INLINE(PyObject *)
SubString_new_object_or_empty(SubString *str)
{
if (str->ptr == NULL) {
return STRINGLIB_NEW(NULL, 0);
}
return STRINGLIB_NEW(str->ptr, str->end - str->ptr);
}
/************************************************************************/
/*********** Output string management functions ****************/
/************************************************************************/
typedef struct {
STRINGLIB_CHAR *ptr;
STRINGLIB_CHAR *end;
PyObject *obj;
Py_ssize_t size_increment;
} OutputString;
/* initialize an OutputString object, reserving size characters */
static int
output_initialize(OutputString *output, Py_ssize_t size)
{
output->obj = STRINGLIB_NEW(NULL, size);
if (output->obj == NULL)
return 0;
output->ptr = STRINGLIB_STR(output->obj);
output->end = STRINGLIB_LEN(output->obj) + output->ptr;
output->size_increment = INITIAL_SIZE_INCREMENT;
return 1;
}
/*
output_extend reallocates the output string buffer.
It returns a status: 0 for a failed reallocation,
1 for success.
*/
static int
output_extend(OutputString *output, Py_ssize_t count)
{
STRINGLIB_CHAR *startptr = STRINGLIB_STR(output->obj);
Py_ssize_t curlen = output->ptr - startptr;
Py_ssize_t maxlen = curlen + count + output->size_increment;
if (STRINGLIB_RESIZE(&output->obj, maxlen) < 0)
return 0;
startptr = STRINGLIB_STR(output->obj);
output->ptr = startptr + curlen;
output->end = startptr + maxlen;
if (output->size_increment < MAX_SIZE_INCREMENT)
output->size_increment *= SIZE_MULTIPLIER;
return 1;
}
/*
output_data dumps characters into our output string
buffer.
In some cases, it has to reallocate the string.
It returns a status: 0 for a failed reallocation,
1 for success.
*/
static int
output_data(OutputString *output, const STRINGLIB_CHAR *s, Py_ssize_t count)
{
if ((count > output->end - output->ptr) && !output_extend(output, count))
return 0;
memcpy(output->ptr, s, count * sizeof(STRINGLIB_CHAR));
output->ptr += count;
return 1;
}
/************************************************************************/
/*********** Format string parsing -- integers and identifiers *********/
/************************************************************************/
static Py_ssize_t
get_integer(const SubString *str)
{
Py_ssize_t accumulator = 0;
Py_ssize_t digitval;
Py_ssize_t oldaccumulator;
STRINGLIB_CHAR *p;
/* empty string is an error */
if (str->ptr >= str->end)
return -1;
for (p = str->ptr; p < str->end; p++) {
digitval = STRINGLIB_TODECIMAL(*p);
if (digitval < 0)
return -1;
/*
This trick was copied from old Unicode format code. It's cute,
but would really suck on an old machine with a slow divide
implementation. Fortunately, in the normal case we do not
expect too many digits.
*/
oldaccumulator = accumulator;
accumulator *= 10;
if ((accumulator+10)/10 != oldaccumulator+1) {
PyErr_Format(PyExc_ValueError,
"Too many decimal digits in format string");
return -1;
}
accumulator += digitval;
}
return accumulator;
}
/************************************************************************/
/******** Functions to get field objects and specification strings ******/
/************************************************************************/
/* do the equivalent of obj.name */
static PyObject *
getattr(PyObject *obj, SubString *name)
{
PyObject *newobj;
PyObject *str = SubString_new_object(name);
if (str == NULL)
return NULL;
newobj = PyObject_GetAttr(obj, str);
Py_DECREF(str);
return newobj;
}
/* do the equivalent of obj[idx], where obj is a sequence */
static PyObject *
getitem_sequence(PyObject *obj, Py_ssize_t idx)
{
return PySequence_GetItem(obj, idx);
}
/* do the equivalent of obj[idx], where obj is not a sequence */
static PyObject *
getitem_idx(PyObject *obj, Py_ssize_t idx)
{
PyObject *newobj;
PyObject *idx_obj = PyInt_FromSsize_t(idx);
if (idx_obj == NULL)
return NULL;
newobj = PyObject_GetItem(obj, idx_obj);
Py_DECREF(idx_obj);
return newobj;
}
/* do the equivalent of obj[name] */
static PyObject *
getitem_str(PyObject *obj, SubString *name)
{
PyObject *newobj;
PyObject *str = SubString_new_object(name);
if (str == NULL)
return NULL;
newobj = PyObject_GetItem(obj, str);
Py_DECREF(str);
return newobj;
}
typedef struct {
/* the entire string we're parsing. we assume that someone else
is managing its lifetime, and that it will exist for the
lifetime of the iterator. can be empty */
SubString str;
/* pointer to where we are inside field_name */
STRINGLIB_CHAR *ptr;
} FieldNameIterator;
static int
FieldNameIterator_init(FieldNameIterator *self, STRINGLIB_CHAR *ptr,
Py_ssize_t len)
{
SubString_init(&self->str, ptr, len);
self->ptr = self->str.ptr;
return 1;
}
static int
_FieldNameIterator_attr(FieldNameIterator *self, SubString *name)
{
STRINGLIB_CHAR c;
name->ptr = self->ptr;
/* return everything until '.' or '[' */
while (self->ptr < self->str.end) {
switch (c = *self->ptr++) {
case '[':
case '.':
/* backup so that we this character will be seen next time */
self->ptr--;
break;
default:
continue;
}
break;
}
/* end of string is okay */
name->end = self->ptr;
return 1;
}
static int
_FieldNameIterator_item(FieldNameIterator *self, SubString *name)
{
STRINGLIB_CHAR c;
name->ptr = self->ptr;
/* return everything until ']' */
while (self->ptr < self->str.end) {
switch (c = *self->ptr++) {
case ']':
break;
default:
continue;
}
break;
}
/* end of string is okay */
/* don't include the ']' */
name->end = self->ptr-1;
return 1;
}
/* returns 0 on error, 1 on non-error termination, and 2 if it returns a value */
static int
FieldNameIterator_next(FieldNameIterator *self, int *is_attribute,
Py_ssize_t *name_idx, SubString *name)
{
/* check at end of input */
if (self->ptr >= self->str.end)
return 1;
switch (*self->ptr++) {
case '.':
*is_attribute = 1;
if (_FieldNameIterator_attr(self, name) == 0) {
return 0;
}
*name_idx = -1;
break;
case '[':
*is_attribute = 0;
if (_FieldNameIterator_item(self, name) == 0) {
return 0;
}
*name_idx = get_integer(name);
break;
default:
/* interal error, can't get here */
assert(0);
return 0;
}
/* empty string is an error */
if (name->ptr == name->end) {
PyErr_SetString(PyExc_ValueError, "Empty attribute in format string");
return 0;
}
return 2;
}
/* input: field_name
output: 'first' points to the part before the first '[' or '.'
'first_idx' is -1 if 'first' is not an integer, otherwise
it's the value of first converted to an integer
'rest' is an iterator to return the rest
*/
static int
field_name_split(STRINGLIB_CHAR *ptr, Py_ssize_t len, SubString *first,
Py_ssize_t *first_idx, FieldNameIterator *rest)
{
STRINGLIB_CHAR c;
STRINGLIB_CHAR *p = ptr;
STRINGLIB_CHAR *end = ptr + len;
/* find the part up until the first '.' or '[' */
while (p < end) {
switch (c = *p++) {
case '[':
case '.':
/* backup so that we this character is available to the
"rest" iterator */
p--;
break;
default:
continue;
}
break;
}
/* set up the return values */
SubString_init(first, ptr, p - ptr);
FieldNameIterator_init(rest, p, end - p);
/* see if "first" is an integer, in which case it's used as an index */
*first_idx = get_integer(first);
/* zero length string is an error */
if (first->ptr >= first->end) {
PyErr_SetString(PyExc_ValueError, "empty field name");
goto error;
}
return 1;
error:
return 0;
}
/*
get_field_object returns the object inside {}, before the
format_spec. It handles getindex and getattr lookups and consumes
the entire input string.
*/
static PyObject *
get_field_object(SubString *input, PyObject *args, PyObject *kwargs)
{
PyObject *obj = NULL;
int ok;
int is_attribute;
SubString name;
SubString first;
Py_ssize_t index;
FieldNameIterator rest;
if (!field_name_split(input->ptr, input->end - input->ptr, &first,
&index, &rest)) {
goto error;
}
if (index == -1) {
/* look up in kwargs */
PyObject *key = SubString_new_object(&first);
if (key == NULL)
goto error;
if ((kwargs == NULL) || (obj = PyDict_GetItem(kwargs, key)) == NULL) {
PyErr_SetString(PyExc_ValueError, "Keyword argument not found "
"in format string");
Py_DECREF(key);
goto error;
}
Py_DECREF(key);
Py_INCREF(obj);
}
else {
/* look up in args */
obj = PySequence_GetItem(args, index);
if (obj == NULL) {
/* translate IndexError to a ValueError */
PyErr_SetString(PyExc_ValueError, "Not enough positional arguments "
"in format string");
goto error;
}
}
/* iterate over the rest of the field_name */
while ((ok = FieldNameIterator_next(&rest, &is_attribute, &index,
&name)) == 2) {
PyObject *tmp;
if (is_attribute)
/* getattr lookup "." */
tmp = getattr(obj, &name);
else
/* getitem lookup "[]" */
if (index == -1)
tmp = getitem_str(obj, &name);
else
if (PySequence_Check(obj))
tmp = getitem_sequence(obj, index);
else
/* not a sequence */
tmp = getitem_idx(obj, index);
if (tmp == NULL)
goto error;
/* assign to obj */
Py_DECREF(obj);
obj = tmp;
}
/* end of iterator, this is the non-error case */
if (ok == 1)
return obj;
error:
Py_XDECREF(obj);
return NULL;
}
/************************************************************************/
/***************** Field rendering functions **************************/
/************************************************************************/
/*
render_field() is the main function in this section. It takes the
field object and field specification string generated by
get_field_and_spec, and renders the field into the output string.
format() does the actual calling of the objects __format__ method.
*/
/* returns fieldobj.__format__(format_spec) */
static PyObject *
format(PyObject *fieldobj, SubString *format_spec)
{
static PyObject *format_str = NULL;
PyObject *meth;
PyObject *spec = NULL;
PyObject *result = NULL;
/* Initialize cached value */
if (format_str == NULL) {
/* Initialize static variable needed by _PyType_Lookup */
format_str = PyUnicode_FromString("__format__");
if (format_str == NULL)
return NULL;
}
/* Make sure the type is initialized. float gets initialized late */
if (Py_Type(fieldobj)->tp_dict == NULL)
if (PyType_Ready(Py_Type(fieldobj)) < 0)
return NULL;
/* we need to create an object out of the pointers we have */
spec = SubString_new_object_or_empty(format_spec);
if (spec == NULL)
goto done;
/* Find the (unbound!) __format__ method (a borrowed reference) */
meth = _PyType_Lookup(Py_Type(fieldobj), format_str);
if (meth == NULL) {
PyErr_Format(PyExc_TypeError,
"Type %.100s doesn't define __format__",
Py_Type(fieldobj)->tp_name);
goto done;
}
/* And call it, binding it to the value */
result = PyObject_CallFunctionObjArgs(meth, fieldobj, spec, NULL);
if (result == NULL)
goto done;
if (!STRINGLIB_CHECK(result)) {
PyErr_SetString(PyExc_TypeError,
"__format__ method did not return "
STRINGLIB_TYPE_NAME);
Py_DECREF(result);
result = NULL;
goto done;
}
done:
Py_XDECREF(spec);
return result;
}
/*
render_field calls fieldobj.__format__(format_spec) method, and
appends to the output.
*/
static int
render_field(PyObject *fieldobj, SubString *format_spec, OutputString *output)
{
int ok = 0;
PyObject *result = format(fieldobj, format_spec);
if (result == NULL)
goto done;
ok = output_data(output,
STRINGLIB_STR(result), STRINGLIB_LEN(result));
done:
Py_XDECREF(result);
return ok;
}
static int
parse_field(SubString *str, SubString *field_name, SubString *format_spec,
STRINGLIB_CHAR *conversion)
{
STRINGLIB_CHAR c = 0;
/* initialize these, as they may be empty */
*conversion = '\0';
SubString_init(format_spec, NULL, 0);
/* search for the field name. it's terminated by the end of the
string, or a ':' or '!' */
field_name->ptr = str->ptr;
while (str->ptr < str->end) {
switch (c = *(str->ptr++)) {
case ':':
case '!':
break;
default:
continue;
}
break;
}
if (c == '!' || c == ':') {
/* we have a format specifier and/or a conversion */
/* don't include the last character */
field_name->end = str->ptr-1;
/* the format specifier is the rest of the string */
format_spec->ptr = str->ptr;
format_spec->end = str->end;
/* see if there's a conversion specifier */
if (c == '!') {
/* there must be another character present */
if (format_spec->ptr >= format_spec->end) {
PyErr_SetString(PyExc_ValueError,
"end of format while looking for conversion "
"specifier");
return 0;
}
*conversion = *(format_spec->ptr++);
/* if there is another character, it must be a colon */
if (format_spec->ptr < format_spec->end) {
c = *(format_spec->ptr++);
if (c != ':') {
PyErr_SetString(PyExc_ValueError,
"expected ':' after format specifier");
return 0;
}
}
}
return 1;
}
else {
/* end of string, there's no format_spec or conversion */
field_name->end = str->ptr;
return 1;
}
}
/************************************************************************/
/******* Output string allocation and escape-to-markup processing ******/
/************************************************************************/
/* MarkupIterator breaks the string into pieces of either literal
text, or things inside {} that need to be marked up. it is
designed to make it easy to wrap a Python iterator around it, for
use with the Formatter class */
typedef struct {
SubString str;
} MarkupIterator;
static int
MarkupIterator_init(MarkupIterator *self, STRINGLIB_CHAR *ptr, Py_ssize_t len)
{
SubString_init(&self->str, ptr, len);
return 1;
}
/* returns 0 on error, 1 on non-error termination, and 2 if it got a
string (or something to be expanded) */
static int
MarkupIterator_next(MarkupIterator *self, SubString *literal,
SubString *field_name, SubString *format_spec,
STRINGLIB_CHAR *conversion,
int *format_spec_needs_expanding)
{
int at_end;
STRINGLIB_CHAR c = 0;
STRINGLIB_CHAR *start;
int count;
Py_ssize_t len;
int markup_follows = 0;
/* initialize all of the output variables */
SubString_init(literal, NULL, 0);
SubString_init(field_name, NULL, 0);
SubString_init(format_spec, NULL, 0);
*conversion = '\0';
*format_spec_needs_expanding = 0;
/* No more input, end of iterator. This is the normal exit
path. */
if (self->str.ptr >= self->str.end)
return 1;
start = self->str.ptr;
/* First read any literal text. Read until the end of string, an
escaped '{' or '}', or an unescaped '{'. In order to never
allocate memory and so I can just pass pointers around, if
there's an escaped '{' or '}' then we'll return the literal
including the brace, but no format object. The next time
through, we'll return the rest of the literal, skipping past
the second consecutive brace. */
while (self->str.ptr < self->str.end) {
switch (c = *(self->str.ptr++)) {
case '{':
case '}':
markup_follows = 1;
break;
default:
continue;
}
break;
}
at_end = self->str.ptr >= self->str.end;
len = self->str.ptr - start;
if ((c == '}') && (at_end || (c != *self->str.ptr))) {
PyErr_SetString(PyExc_ValueError, "Single '}' encountered "
"in format string");
return 0;
}
if (at_end && c == '{') {
PyErr_SetString(PyExc_ValueError, "Single '{' encountered "
"in format string");
return 0;
}
if (!at_end) {
if (c == *self->str.ptr) {
/* escaped } or {, skip it in the input. there is no
markup object following us, just this literal text */
self->str.ptr++;
markup_follows = 0;
}
else
len--;
}
/* record the literal text */
literal->ptr = start;
literal->end = start + len;
if (!markup_follows)
return 2;
/* this is markup, find the end of the string by counting nested
braces. note that this prohibits escaped braces, so that
format_specs cannot have braces in them. */
count = 1;
start = self->str.ptr;
/* we know we can't have a zero length string, so don't worry
about that case */
while (self->str.ptr < self->str.end) {
switch (c = *(self->str.ptr++)) {
case '{':
/* the format spec needs to be recursively expanded.
this is an optimization, and not strictly needed */
*format_spec_needs_expanding = 1;
count++;
break;
case '}':
count--;
if (count <= 0) {
/* we're done. parse and get out */
SubString s;
SubString_init(&s, start, self->str.ptr - 1 - start);
if (parse_field(&s, field_name, format_spec, conversion) == 0)
return 0;
/* a zero length field_name is an error */
if (field_name->ptr == field_name->end) {
PyErr_SetString(PyExc_ValueError, "zero length field name "
"in format");
return 0;
}
/* success */
return 2;
}
break;
}
}
/* end of string while searching for matching '}' */
PyErr_SetString(PyExc_ValueError, "unmatched '{' in format");
return 0;
}
/* do the !r or !s conversion on obj */
static PyObject *
do_conversion(PyObject *obj, STRINGLIB_CHAR conversion)
{
/* XXX in pre-3.0, do we need to convert this to unicode, since it
might have returned a string? */
switch (conversion) {
case 'r':
return PyObject_Repr(obj);
case 's':
return PyObject_Unicode(obj);
default:
PyErr_Format(PyExc_ValueError,
"Unknown converion specifier %c",
conversion);
return NULL;
}
}
/* given:
{field_name!conversion:format_spec}
compute the result and write it to output.
format_spec_needs_expanding is an optimization. if it's false,
just output the string directly, otherwise recursively expand the
format_spec string. */
static int
output_markup(SubString *field_name, SubString *format_spec,
int format_spec_needs_expanding, STRINGLIB_CHAR conversion,
OutputString *output, PyObject *args, PyObject *kwargs,
int *recursion_level)
{
PyObject *tmp = NULL;
PyObject *fieldobj = NULL;
SubString expanded_format_spec;
SubString *actual_format_spec;
int result = 0;
/* convert field_name to an object */
fieldobj = get_field_object(field_name, args, kwargs);
if (fieldobj == NULL)
goto done;
if (conversion != '\0') {
tmp = do_conversion(fieldobj, conversion);
if (tmp == NULL)
goto done;
/* do the assignment, transferring ownership: fieldobj = tmp */
Py_DECREF(fieldobj);
fieldobj = tmp;
tmp = NULL;
}
/* if needed, recurively compute the format_spec */
if (format_spec_needs_expanding) {
tmp = build_string(format_spec, args, kwargs, recursion_level);
if (tmp == NULL)
goto done;
/* note that in the case we're expanding the format string,
tmp must be kept around until after the call to
render_field. */
SubString_init(&expanded_format_spec,
STRINGLIB_STR(tmp), STRINGLIB_LEN(tmp));
actual_format_spec = &expanded_format_spec;
}
else
actual_format_spec = format_spec;
if (render_field(fieldobj, actual_format_spec, output) == 0)
goto done;
result = 1;
done:
Py_XDECREF(fieldobj);
Py_XDECREF(tmp);
return result;
}
/*
do_markup is the top-level loop for the format() function. It
searches through the format string for escapes to markup codes, and
calls other functions to move non-markup text to the output,
and to perform the markup to the output.
*/
static int
do_markup(SubString *input, PyObject *args, PyObject *kwargs,
OutputString *output, int *recursion_level)
{
MarkupIterator iter;
int format_spec_needs_expanding;
int result;
SubString literal;
SubString field_name;
SubString format_spec;
STRINGLIB_CHAR conversion;
MarkupIterator_init(&iter, input->ptr, input->end - input->ptr);
while ((result = MarkupIterator_next(&iter, &literal, &field_name,
&format_spec, &conversion,
&format_spec_needs_expanding)) == 2) {
if (!output_data(output, literal.ptr, literal.end - literal.ptr))
return 0;
if (field_name.ptr != field_name.end)
if (!output_markup(&field_name, &format_spec,
format_spec_needs_expanding, conversion, output,
args, kwargs, recursion_level))
return 0;
}
return result;
}
/*
build_string allocates the output string and then
calls do_markup to do the heavy lifting.
*/
static PyObject *
build_string(SubString *input, PyObject *args, PyObject *kwargs,
int *recursion_level)
{
OutputString output;
PyObject *result = NULL;
Py_ssize_t count;
output.obj = NULL; /* needed so cleanup code always works */
/* check the recursion level */
(*recursion_level)--;
if (*recursion_level < 0) {
PyErr_SetString(PyExc_ValueError,
"Max string recursion exceeded");
goto done;
}
/* initial size is the length of the format string, plus the size
increment. seems like a reasonable default */
if (!output_initialize(&output,
input->end - input->ptr +
INITIAL_SIZE_INCREMENT))
goto done;
if (!do_markup(input, args, kwargs, &output, recursion_level)) {
goto done;
}
count = output.ptr - STRINGLIB_STR(output.obj);
if (STRINGLIB_RESIZE(&output.obj, count) < 0) {
goto done;
}
/* transfer ownership to result */
result = output.obj;
output.obj = NULL;
done:
(*recursion_level)++;
Py_XDECREF(output.obj);
return result;
}
/************************************************************************/
/*********** main routine ***********************************************/
/************************************************************************/
/* this is the main entry point */
static PyObject *
do_string_format(PyObject *self, PyObject *args, PyObject *kwargs)
{
SubString input;
/* PEP 3101 says only 2 levels, so that
"{0:{1}}".format('abc', 's') # works
"{0:{1:{2}}}".format('abc', 's', '') # fails
*/
int recursion_level = 2;
SubString_init(&input, STRINGLIB_STR(self), STRINGLIB_LEN(self));
return build_string(&input, args, kwargs, &recursion_level);
}
/************************************************************************/
/*********** formatteriterator ******************************************/
/************************************************************************/
/* This is used to implement string.Formatter.vparse(). It exists so
Formatter can share code with the built in unicode.format() method.
It's really just a wrapper around MarkupIterator that is callable
from Python. */
typedef struct {
PyObject_HEAD
PyUnicodeObject *str;
MarkupIterator it_markup;
} formatteriterobject;
static void
formatteriter_dealloc(formatteriterobject *it)
{
Py_XDECREF(it->str);
PyObject_FREE(it);
}
/* returns a tuple:
(literal, field_name, format_spec, conversion)
literal is any literal text to output. might be zero length
field_name is the string before the ':'. might be None
format_spec is the string after the ':'. mibht be None
conversion is either None, or the string after the '!'
*/
static PyObject *
formatteriter_next(formatteriterobject *it)
{
SubString literal;
SubString field_name;
SubString format_spec;
Py_UNICODE conversion;
int format_spec_needs_expanding;
int result = MarkupIterator_next(&it->it_markup, &literal, &field_name,
&format_spec, &conversion,
&format_spec_needs_expanding);
/* all of the SubString objects point into it->str, so no
memory management needs to be done on them */
assert(0 <= result && result <= 2);
if (result == 0 || result == 1)
/* if 0, error has already been set, if 1, iterator is empty */
return NULL;
else {
PyObject *literal_str = NULL;
PyObject *field_name_str = NULL;
PyObject *format_spec_str = NULL;
PyObject *conversion_str = NULL;
PyObject *tuple = NULL;
int has_field = field_name.ptr != field_name.end;
literal_str = SubString_new_object(&literal);
if (literal_str == NULL)
goto done;
field_name_str = SubString_new_object(&field_name);
if (field_name_str == NULL)
goto done;
/* if field_name is non-zero length, return a string for
format_spec (even if zero length), else return None */
format_spec_str = (has_field ?
SubString_new_object_or_empty :
SubString_new_object)(&format_spec);
if (format_spec_str == NULL)
goto done;
/* if the conversion is not specified, return a None,
otherwise create a one length string with the conversion
character */
if (conversion == '\0') {
conversion_str = Py_None;
Py_INCREF(conversion_str);
}
else
conversion_str = PyUnicode_FromUnicode(&conversion, 1);
if (conversion_str == NULL)
goto done;
tuple = PyTuple_Pack(4, literal_str, field_name_str, format_spec_str,
conversion_str);
done:
Py_XDECREF(literal_str);
Py_XDECREF(field_name_str);
Py_XDECREF(format_spec_str);
Py_XDECREF(conversion_str);
return tuple;
}
}
static PyMethodDef formatteriter_methods[] = {
{NULL, NULL} /* sentinel */
};
PyTypeObject PyFormatterIter_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"formatteriterator", /* tp_name */
sizeof(formatteriterobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)formatteriter_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)formatteriter_next, /* tp_iternext */
formatteriter_methods, /* tp_methods */
0,
};
/* unicode_formatter_parser is used to implement
string.Formatter.vformat. it parses a string and returns tuples
describing the parsed elements. It's a wrapper around
stringlib/string_format.h's MarkupIterator */
static PyObject *
formatter_parser(PyUnicodeObject *self)
{
formatteriterobject *it;
it = PyObject_New(formatteriterobject, &PyFormatterIter_Type);
if (it == NULL)
return NULL;
/* take ownership, give the object to the iterator */
Py_INCREF(self);
it->str = self;
/* initialize the contained MarkupIterator */
MarkupIterator_init(&it->it_markup,
PyUnicode_AS_UNICODE(self),
PyUnicode_GET_SIZE(self));
return (PyObject *)it;
}
/************************************************************************/
/*********** fieldnameiterator ******************************************/
/************************************************************************/
/* This is used to implement string.Formatter.vparse(). It parses the
field name into attribute and item values. It's a Python-callable
wrapper around FieldNameIterator */
typedef struct {
PyObject_HEAD
PyUnicodeObject *str;
FieldNameIterator it_field;
} fieldnameiterobject;
static void
fieldnameiter_dealloc(fieldnameiterobject *it)
{
Py_XDECREF(it->str);
PyObject_FREE(it);
}
/* returns a tuple:
(is_attr, value)
is_attr is true if we used attribute syntax (e.g., '.foo')
false if we used index syntax (e.g., '[foo]')
value is an integer or string
*/
static PyObject *
fieldnameiter_next(fieldnameiterobject *it)
{
int result;
int is_attr;
Py_ssize_t idx;
SubString name;
result = FieldNameIterator_next(&it->it_field, &is_attr,
&idx, &name);
if (result == 0 || result == 1)
/* if 0, error has already been set, if 1, iterator is empty */
return NULL;
else {
PyObject* result = NULL;
PyObject* is_attr_obj = NULL;
PyObject* obj = NULL;
is_attr_obj = PyBool_FromLong(is_attr);
if (is_attr_obj == NULL)
goto done;
/* either an integer or a string */
if (idx != -1)
obj = PyInt_FromSsize_t(idx);
else
obj = SubString_new_object(&name);
if (obj == NULL)
goto done;
/* return a tuple of values */
result = PyTuple_Pack(2, is_attr_obj, obj);
done:
Py_XDECREF(is_attr_obj);
Py_XDECREF(obj);
return result;
}
}
static PyMethodDef fieldnameiter_methods[] = {
{NULL, NULL} /* sentinel */
};
static PyTypeObject PyFieldNameIter_Type = {
PyVarObject_HEAD_INIT(&PyType_Type, 0)
"fieldnameiterator", /* tp_name */
sizeof(fieldnameiterobject), /* tp_basicsize */
0, /* tp_itemsize */
/* methods */
(destructor)fieldnameiter_dealloc, /* tp_dealloc */
0, /* tp_print */
0, /* tp_getattr */
0, /* tp_setattr */
0, /* tp_compare */
0, /* tp_repr */
0, /* tp_as_number */
0, /* tp_as_sequence */
0, /* tp_as_mapping */
0, /* tp_hash */
0, /* tp_call */
0, /* tp_str */
PyObject_GenericGetAttr, /* tp_getattro */
0, /* tp_setattro */
0, /* tp_as_buffer */
Py_TPFLAGS_DEFAULT, /* tp_flags */
0, /* tp_doc */
0, /* tp_traverse */
0, /* tp_clear */
0, /* tp_richcompare */
0, /* tp_weaklistoffset */
PyObject_SelfIter, /* tp_iter */
(iternextfunc)fieldnameiter_next, /* tp_iternext */
fieldnameiter_methods, /* tp_methods */
0};
/* unicode_formatter_field_name_split is used to implement
string.Formatter.vformat. it takes an PEP 3101 "field name", and
returns a tuple of (first, rest): "first", the part before the
first '.' or '['; and "rest", an iterator for the rest of the field
name. it's a wrapper around stringlib/string_format.h's
field_name_split. The iterator it returns is a
FieldNameIterator */
static PyObject *
formatter_field_name_split(PyUnicodeObject *self)
{
SubString first;
Py_ssize_t first_idx;
fieldnameiterobject *it;
PyObject *first_obj = NULL;
PyObject *result = NULL;
it = PyObject_New(fieldnameiterobject, &PyFieldNameIter_Type);
if (it == NULL)
return NULL;
/* take ownership, give the object to the iterator. this is
just to keep the field_name alive */
Py_INCREF(self);
it->str = self;
if (!field_name_split(STRINGLIB_STR(self),
STRINGLIB_LEN(self),
&first, &first_idx, &it->it_field))
goto done;
/* first becomes an integer, if possible; else a string */
if (first_idx != -1)
first_obj = PyInt_FromSsize_t(first_idx);
else
/* convert "first" into a string object */
first_obj = SubString_new_object(&first);
if (first_obj == NULL)
goto done;
/* return a tuple of values */
result = PyTuple_Pack(2, first_obj, it);
done:
Py_XDECREF(it);
Py_XDECREF(first_obj);
return result;
}
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