Objects/stringobject.c

/* String object implementation */

#define PY_SSIZE_T_CLEAN

#include "Python.h"

#include <ctype.h>

#ifdef COUNT_ALLOCS
int null_strings, one_strings;
#endif

static PyStringObject *characters[UCHAR_MAX + 1];
static PyStringObject *nullstring;

/* This dictionary holds all interned strings.  Note that references to
   strings in this dictionary are *not* counted in the string's ob_refcnt.
   When the interned string reaches a refcnt of 0 the string deallocation
   function will delete the reference from this dictionary.

   Another way to look at this is that to say that the actual reference
   count of a string is:  s->ob_refcnt + (s->ob_sstate?2:0)
*/
static PyObject *interned;

/*
   For both PyString_FromString() and PyString_FromStringAndSize(), the
   parameter `size' denotes number of characters to allocate, not counting any
   null terminating character.

   For PyString_FromString(), the parameter `str' points to a null-terminated
   string containing exactly `size' bytes.

   For PyString_FromStringAndSize(), the parameter the parameter `str' is
   either NULL or else points to a string containing at least `size' bytes.
   For PyString_FromStringAndSize(), the string in the `str' parameter does
   not have to be null-terminated.  (Therefore it is safe to construct a
   substring by calling `PyString_FromStringAndSize(origstring, substrlen)'.)
   If `str' is NULL then PyString_FromStringAndSize() will allocate `size+1'
   bytes (setting the last byte to the null terminating character) and you can
   fill in the data yourself.  If `str' is non-NULL then the resulting
   PyString object must be treated as immutable and you must not fill in nor
   alter the data yourself, since the strings may be shared.

   The PyObject member `op->ob_size', which denotes the number of "extra
   items" in a variable-size object, will contain the number of bytes
   allocated for string data, not counting the null terminating character.  It
   is therefore equal to the equal to the `size' parameter (for
   PyString_FromStringAndSize()) or the length of the string in the `str'
   parameter (for PyString_FromString()).
*/
PyObject *
PyString_FromStringAndSize(const char *str, Py_ssize_t size)
{
	register PyStringObject *op;
	assert(size >= 0);
	if (size == 0 && (op = nullstring) != NULL) {
#ifdef COUNT_ALLOCS
		null_strings++;
#endif
		Py_INCREF(op);
		return (PyObject *)op;
	}
	if (size == 1 && str != NULL &&
	    (op = characters[*str & UCHAR_MAX]) != NULL)
	{
#ifdef COUNT_ALLOCS
		one_strings++;
#endif
		Py_INCREF(op);
		return (PyObject *)op;
	}

	/* Inline PyObject_NewVar */
	op = (PyStringObject *)PyObject_MALLOC(sizeof(PyStringObject) + size);
	if (op == NULL)
		return PyErr_NoMemory();
	PyObject_INIT_VAR(op, &PyString_Type, size);
	op->ob_shash = -1;
	op->ob_sstate = SSTATE_NOT_INTERNED;
	if (str != NULL)
		Py_MEMCPY(op->ob_sval, str, size);
	op->ob_sval[size] = '\0';
	/* share short strings */
	if (size == 0) {
		PyObject *t = (PyObject *)op;
		PyString_InternInPlace(&t);
		op = (PyStringObject *)t;
		nullstring = op;
		Py_INCREF(op);
	} else if (size == 1 && str != NULL) {
		PyObject *t = (PyObject *)op;
		PyString_InternInPlace(&t);
		op = (PyStringObject *)t;
		characters[*str & UCHAR_MAX] = op;
		Py_INCREF(op);
	}
	return (PyObject *) op;
}

PyObject *
PyString_FromString(const char *str)
{
	register size_t size;
	register PyStringObject *op;

	assert(str != NULL);
	size = strlen(str);
	if (size > PY_SSIZE_T_MAX) {
		PyErr_SetString(PyExc_OverflowError,
			"string is too long for a Python string");
		return NULL;
	}
	if (size == 0 && (op = nullstring) != NULL) {
#ifdef COUNT_ALLOCS
		null_strings++;
#endif
		Py_INCREF(op);
		return (PyObject *)op;
	}
	if (size == 1 && (op = characters[*str & UCHAR_MAX]) != NULL) {
#ifdef COUNT_ALLOCS
		one_strings++;
#endif
		Py_INCREF(op);
		return (PyObject *)op;
	}

	/* Inline PyObject_NewVar */
	op = (PyStringObject *)PyObject_MALLOC(sizeof(PyStringObject) + size);
	if (op == NULL)
		return PyErr_NoMemory();
	PyObject_INIT_VAR(op, &PyString_Type, size);
	op->ob_shash = -1;
	op->ob_sstate = SSTATE_NOT_INTERNED;
	Py_MEMCPY(op->ob_sval, str, size+1);
	/* share short strings */
	if (size == 0) {
		PyObject *t = (PyObject *)op;
		PyString_InternInPlace(&t);
		op = (PyStringObject *)t;
		nullstring = op;
		Py_INCREF(op);
	} else if (size == 1) {
		PyObject *t = (PyObject *)op;
		PyString_InternInPlace(&t);
		op = (PyStringObject *)t;
		characters[*str & UCHAR_MAX] = op;
		Py_INCREF(op);
	}
	return (PyObject *) op;
}

PyObject *
PyString_FromFormatV(const char *format, va_list vargs)
{
	va_list count;
	Py_ssize_t n = 0;
	const char* f;
	char *s;
	PyObject* string;

#ifdef VA_LIST_IS_ARRAY
	Py_MEMCPY(count, vargs, sizeof(va_list));
#else
#ifdef  __va_copy
	__va_copy(count, vargs);
#else
	count = vargs;
#endif
#endif
	/* step 1: figure out how large a buffer we need */
	for (f = format; *f; f++) {
		if (*f == '%') {
			const char* p = f;
			while (*++f && *f != '%' && !isalpha(Py_CHARMASK(*f)))
				;

			/* skip the 'l' or 'z' in {%ld, %zd, %lu, %zu} since
			 * they don't affect the amount of space we reserve.
			 */
			if ((*f == 'l' || *f == 'z') &&
					(f[1] == 'd' || f[1] == 'u'))
				++f;

			switch (*f) {
			case 'c':
				(void)va_arg(count, int);
				/* fall through... */
			case '%':
				n++;
				break;
			case 'd': case 'u': case 'i': case 'x':
				(void) va_arg(count, int);
				/* 20 bytes is enough to hold a 64-bit
				   integer.  Decimal takes the most space.
				   This isn't enough for octal. */
				n += 20;
				break;
			case 's':
				s = va_arg(count, char*);
				n += strlen(s);
				break;
			case 'p':
				(void) va_arg(count, int);
				/* maximum 64-bit pointer representation:
				 * 0xffffffffffffffff
				 * so 19 characters is enough.
				 * XXX I count 18 -- what's the extra for?
				 */
				n += 19;
				break;
			default:
				/* if we stumble upon an unknown
				   formatting code, copy the rest of
				   the format string to the output
				   string. (we cannot just skip the
				   code, since there's no way to know
				   what's in the argument list) */
				n += strlen(p);
				goto expand;
			}
		} else
			n++;
	}
 expand:
	/* step 2: fill the buffer */
	/* Since we've analyzed how much space we need for the worst case,
	   use sprintf directly instead of the slower PyOS_snprintf. */
	string = PyString_FromStringAndSize(NULL, n);
	if (!string)
		return NULL;

	s = PyString_AsString(string);

	for (f = format; *f; f++) {
		if (*f == '%') {
			const char* p = f++;
			Py_ssize_t i;
			int longflag = 0;
			int size_tflag = 0;
			/* parse the width.precision part (we're only
			   interested in the precision value, if any) */
			n = 0;
			while (isdigit(Py_CHARMASK(*f)))
				n = (n*10) + *f++ - '0';
			if (*f == '.') {
				f++;
				n = 0;
				while (isdigit(Py_CHARMASK(*f)))
					n = (n*10) + *f++ - '0';
			}
			while (*f && *f != '%' && !isalpha(Py_CHARMASK(*f)))
				f++;
			/* handle the long flag, but only for %ld and %lu.
			   others can be added when necessary. */
			if (*f == 'l' && (f[1] == 'd' || f[1] == 'u')) {
				longflag = 1;
				++f;
			}
			/* handle the size_t flag. */
			if (*f == 'z' && (f[1] == 'd' || f[1] == 'u')) {
				size_tflag = 1;
				++f;
			}

			switch (*f) {
			case 'c':
				*s++ = va_arg(vargs, int);
				break;
			case 'd':
				if (longflag)
					sprintf(s, "%ld", va_arg(vargs, long));
				else if (size_tflag)
					sprintf(s, "%" PY_FORMAT_SIZE_T "d",
					        va_arg(vargs, Py_ssize_t));
				else
					sprintf(s, "%d", va_arg(vargs, int));
				s += strlen(s);
				break;
			case 'u':
				if (longflag)
					sprintf(s, "%lu",
						va_arg(vargs, unsigned long));
				else if (size_tflag)
					sprintf(s, "%" PY_FORMAT_SIZE_T "u",
					        va_arg(vargs, size_t));
				else
					sprintf(s, "%u",
						va_arg(vargs, unsigned int));
				s += strlen(s);
				break;
			case 'i':
				sprintf(s, "%i", va_arg(vargs, int));
				s += strlen(s);
				break;
			case 'x':
				sprintf(s, "%x", va_arg(vargs, int));
				s += strlen(s);
				break;
			case 's':
				p = va_arg(vargs, char*);
				i = strlen(p);
				if (n > 0 && i > n)
					i = n;
				Py_MEMCPY(s, p, i);
				s += i;
				break;
			case 'p':
				sprintf(s, "%p", va_arg(vargs, void*));
				/* %p is ill-defined:  ensure leading 0x. */
				if (s[1] == 'X')
					s[1] = 'x';
				else if (s[1] != 'x') {
					memmove(s+2, s, strlen(s)+1);
					s[0] = '0';
					s[1] = 'x';
				}
				s += strlen(s);
				break;
			case '%':
				*s++ = '%';
				break;
			default:
				strcpy(s, p);
				s += strlen(s);
				goto end;
			}
		} else
			*s++ = *f;
	}

 end:
	_PyString_Resize(&string, s - PyString_AS_STRING(string));
	return string;
}

PyObject *
PyString_FromFormat(const char *format, ...)
{
	PyObject* ret;
	va_list vargs;

#ifdef HAVE_STDARG_PROTOTYPES
	va_start(vargs, format);
#else
	va_start(vargs);
#endif
	ret = PyString_FromFormatV(format, vargs);
	va_end(vargs);
	return ret;
}


PyObject *PyString_Decode(const char *s,
			  Py_ssize_t size,
			  const char *encoding,
			  const char *errors)
{
    PyObject *v, *str;

    str = PyString_FromStringAndSize(s, size);
    if (str == NULL)
	return NULL;
    v = PyString_AsDecodedString(str, encoding, errors);
    Py_DECREF(str);
    return v;
}

PyObject *PyString_AsDecodedObject(PyObject *str,
				   const char *encoding,
				   const char *errors)
{
    PyObject *v;

    if (!PyString_Check(str)) {
        PyErr_BadArgument();
        goto onError;
    }

    if (encoding == NULL) {
	encoding = PyUnicode_GetDefaultEncoding();
    }

    /* Decode via the codec registry */
    v = PyCodec_Decode(str, encoding, errors);
    if (v == NULL)
        goto onError;

    return v;

 onError:
    return NULL;
}

PyObject *PyString_AsDecodedString(PyObject *str,
				   const char *encoding,
				   const char *errors)
{
    PyObject *v;

    v = PyString_AsDecodedObject(str, encoding, errors);
    if (v == NULL)
        goto onError;

    /* Convert Unicode to a string using the default encoding */
    if (PyUnicode_Check(v)) {
	PyObject *temp = v;
	v = PyUnicode_AsEncodedString(v, NULL, NULL);
	Py_DECREF(temp);
	if (v == NULL)
	    goto onError;
    }
    if (!PyString_Check(v)) {
        PyErr_Format(PyExc_TypeError,
                     "decoder did not return a string object (type=%.400s)",
                     v->ob_type->tp_name);
        Py_DECREF(v);
        goto onError;
    }

    return v;

 onError:
    return NULL;
}

PyObject *PyString_Encode(const char *s,
			  Py_ssize_t size,
			  const char *encoding,
			  const char *errors)
{
    PyObject *v, *str;

    str = PyString_FromStringAndSize(s, size);
    if (str == NULL)
	return NULL;
    v = PyString_AsEncodedString(str, encoding, errors);
    Py_DECREF(str);
    return v;
}

PyObject *PyString_AsEncodedObject(PyObject *str,
				   const char *encoding,
				   const char *errors)
{
    PyObject *v;

    if (!PyString_Check(str)) {
        PyErr_BadArgument();
        goto onError;
    }

    if (encoding == NULL) {
	encoding = PyUnicode_GetDefaultEncoding();
    }

    /* Encode via the codec registry */
    v = PyCodec_Encode(str, encoding, errors);
    if (v == NULL)
        goto onError;

    return v;

 onError:
    return NULL;
}

PyObject *PyString_AsEncodedString(PyObject *str,
				   const char *encoding,
				   const char *errors)
{
    PyObject *v;

    v = PyString_AsEncodedObject(str, encoding, errors);
    if (v == NULL)
        goto onError;

    /* Convert Unicode to a string using the default encoding */
    if (PyUnicode_Check(v)) {
	PyObject *temp = v;
	v = PyUnicode_AsEncodedString(v, NULL, NULL);
	Py_DECREF(temp);
	if (v == NULL)
	    goto onError;
    }
    if (!PyString_Check(v)) {
        PyErr_Format(PyExc_TypeError,
                     "encoder did not return a string object (type=%.400s)",
                     v->ob_type->tp_name);
        Py_DECREF(v);
        goto onError;
    }

    return v;

 onError:
    return NULL;
}

static void
string_dealloc(PyObject *op)
{
	switch (PyString_CHECK_INTERNED(op)) {
		case SSTATE_NOT_INTERNED:
			break;

		case SSTATE_INTERNED_MORTAL:
			/* revive dead object temporarily for DelItem */
			op->ob_refcnt = 3;
			if (PyDict_DelItem(interned, op) != 0)
				Py_FatalError(
					"deletion of interned string failed");
			break;

		case SSTATE_INTERNED_IMMORTAL:
			Py_FatalError("Immortal interned string died.");

		default:
			Py_FatalError("Inconsistent interned string state.");
	}
	op->ob_type->tp_free(op);
}

/* Unescape a backslash-escaped string. If unicode is non-zero,
   the string is a u-literal. If recode_encoding is non-zero,
   the string is UTF-8 encoded and should be re-encoded in the
   specified encoding.  */

PyObject *PyString_DecodeEscape(const char *s,
				Py_ssize_t len,
				const char *errors,
				Py_ssize_t unicode,
				const char *recode_encoding)
{
	int c;
	char *p, *buf;
	const char *end;
	PyObject *v;
	Py_ssize_t newlen = recode_encoding ? 4*len:len;
	v = PyString_FromStringAndSize((char *)NULL, newlen);
	if (v == NULL)
		return NULL;
	p = buf = PyString_AsString(v);
	end = s + len;
	while (s < end) {
		if (*s != '\\') {
		  non_esc:
			if (recode_encoding && (*s & 0x80)) {
				PyObject *u, *w;
				char *r;
				const char* t;
				Py_ssize_t rn;
				t = s;
				/* Decode non-ASCII bytes as UTF-8. */
				while (t < end && (*t & 0x80)) t++;
				u = PyUnicode_DecodeUTF8(s, t - s, errors);
				if(!u) goto failed;

				/* Recode them in target encoding. */
				w = PyUnicode_AsEncodedString(
					u, recode_encoding, errors);
				Py_DECREF(u);
				if (!w)	goto failed;

				/* Append bytes to output buffer. */
				assert(PyString_Check(w));
				r = PyString_AS_STRING(w);
				rn = PyString_GET_SIZE(w);
				Py_MEMCPY(p, r, rn);
				p += rn;
				Py_DECREF(w);
				s = t;
			} else {
				*p++ = *s++;
			}
			continue;
		}
		s++;
                if (s==end) {
			PyErr_SetString(PyExc_ValueError,
					"Trailing \\ in string");
			goto failed;
		}
		switch (*s++) {
		/* XXX This assumes ASCII! */
		case '\n': break;
		case '\\': *p++ = '\\'; break;
		case '\'': *p++ = '\''; break;
		case '\"': *p++ = '\"'; break;
		case 'b': *p++ = '\b'; break;
		case 'f': *p++ = '\014'; break; /* FF */
		case 't': *p++ = '\t'; break;
		case 'n': *p++ = '\n'; break;
		case 'r': *p++ = '\r'; break;
		case 'v': *p++ = '\013'; break; /* VT */
		case 'a': *p++ = '\007'; break; /* BEL, not classic C */
		case '0': case '1': case '2': case '3':
		case '4': case '5': case '6': case '7':
			c = s[-1] - '0';
			if ('0' <= *s && *s <= '7') {
				c = (c<<3) + *s++ - '0';
				if ('0' <= *s && *s <= '7')
					c = (c<<3) + *s++ - '0';
			}
			*p++ = c;
			break;
		case 'x':
			if (isxdigit(Py_CHARMASK(s[0]))
			    && isxdigit(Py_CHARMASK(s[1]))) {
				unsigned int x = 0;
				c = Py_CHARMASK(*s);
				s++;
				if (isdigit(c))
					x = c - '0';
				else if (islower(c))
					x = 10 + c - 'a';
				else
					x = 10 + c - 'A';
				x = x << 4;
				c = Py_CHARMASK(*s);
				s++;
				if (isdigit(c))
					x += c - '0';
				else if (islower(c))
					x += 10 + c - 'a';
				else
					x += 10 + c - 'A';
				*p++ = x;
				break;
			}
			if (!errors || strcmp(errors, "strict") == 0) {
				PyErr_SetString(PyExc_ValueError,
						"invalid \\x escape");
				goto failed;
			}
			if (strcmp(errors, "replace") == 0) {
				*p++ = '?';
			} else if (strcmp(errors, "ignore") == 0)
				/* do nothing */;
			else {
				PyErr_Format(PyExc_ValueError,
					     "decoding error; "
					     "unknown error handling code: %.400s",
					     errors);
				goto failed;
			}
		default:
			*p++ = '\\';
			s--;
			goto non_esc; /* an arbitry number of unescaped
					 UTF-8 bytes may follow. */
		}
	}
	if (p-buf < newlen)
		_PyString_Resize(&v, p - buf);
	return v;
  failed:
	Py_DECREF(v);
	return NULL;
}

/* -------------------------------------------------------------------- */
/* object api */

static Py_ssize_t
string_getsize(register PyObject *op)
{
    	char *s;
    	Py_ssize_t len;
	if (PyString_AsStringAndSize(op, &s, &len))
		return -1;
	return len;
}

static /*const*/ char *
string_getbuffer(register PyObject *op)
{
    	char *s;
    	Py_ssize_t len;
	if (PyString_AsStringAndSize(op, &s, &len))
		return NULL;
	return s;
}

Py_ssize_t
PyString_Size(register PyObject *op)
{
	if (PyUnicode_Check(op)) {
		op = _PyUnicode_AsDefaultEncodedString(op, NULL);
		if (!op)
			return -1;
	}
	if (!PyString_Check(op))
		return string_getsize(op);
	return ((PyStringObject *)op) -> ob_size;
}

/*const*/ char *
PyString_AsString(register PyObject *op)
{
	if (PyUnicode_Check(op)) {
		op = _PyUnicode_AsDefaultEncodedString(op, NULL);
		if (!op)
			return NULL;
	}
	if (!PyString_Check(op))
		return string_getbuffer(op);
	return ((PyStringObject *)op) -> ob_sval;
}

int
PyString_AsStringAndSize(register PyObject *obj,
			 register char **s,
			 register Py_ssize_t *len)
{
	if (s == NULL) {
		PyErr_BadInternalCall();
		return -1;
	}

	if (!PyString_Check(obj)) {
		if (PyUnicode_Check(obj)) {
			obj = _PyUnicode_AsDefaultEncodedString(obj, NULL);
			if (obj == NULL)
				return -1;
		}
		else
		{
			PyErr_Format(PyExc_TypeError,
				     "expected string, "
				     "%.200s found", obj->ob_type->tp_name);
			return -1;
		}
	}

	*s = PyString_AS_STRING(obj);
	if (len != NULL)
		*len = PyString_GET_SIZE(obj);
	else if (strlen(*s) != (size_t)PyString_GET_SIZE(obj)) {
		PyErr_SetString(PyExc_TypeError,
				"expected string without null bytes");
		return -1;
	}
	return 0;
}

/* -------------------------------------------------------------------- */
/* Methods */

#define STRINGLIB_CHAR char

#define STRINGLIB_CMP memcmp
#define STRINGLIB_LEN PyString_GET_SIZE
#define STRINGLIB_NEW PyString_FromStringAndSize
#define STRINGLIB_STR PyString_AS_STRING

#define STRINGLIB_EMPTY nullstring

#include "stringlib/fastsearch.h"

#include "stringlib/count.h"
#include "stringlib/find.h"
#include "stringlib/partition.h"


static int
string_print(PyStringObject *op, FILE *fp, int flags)
{
	Py_ssize_t i;
	char c;
	int quote;

	/* XXX Ought to check for interrupts when writing long strings */
	if (! PyString_CheckExact(op)) {
		int ret;
		/* A str subclass may have its own __str__ method. */
		op = (PyStringObject *) PyObject_Str((PyObject *)op);
		if (op == NULL)
			return -1;
		ret = string_print(op, fp, flags);
		Py_DECREF(op);
		return ret;
	}
	if (flags & Py_PRINT_RAW) {
		char *data = op->ob_sval;
		Py_ssize_t size = op->ob_size;
		while (size > INT_MAX) {
			/* Very long strings cannot be written atomically.
			 * But don't write exactly INT_MAX bytes at a time
			 * to avoid memory aligment issues.
			 */
			const int chunk_size = INT_MAX & ~0x3FFF;
			fwrite(data, 1, chunk_size, fp);
			data += chunk_size;
			size -= chunk_size;
		}
#ifdef __VMS
                if (size) fwrite(data, (int)size, 1, fp);
#else
                fwrite(data, 1, (int)size, fp);
#endif
		return 0;
	}

	/* figure out which quote to use; single is preferred */
	quote = '\'';
	if (memchr(op->ob_sval, '\'', op->ob_size) &&
	    !memchr(op->ob_sval, '"', op->ob_size))
		quote = '"';

	fputc(quote, fp);
	for (i = 0; i < op->ob_size; i++) {
		c = op->ob_sval[i];
		if (c == quote || c == '\\')
			fprintf(fp, "\\%c", c);
                else if (c == '\t')
                        fprintf(fp, "\\t");
                else if (c == '\n')
                        fprintf(fp, "\\n");
                else if (c == '\r')
                        fprintf(fp, "\\r");
		else if (c < ' ' || c >= 0x7f)
			fprintf(fp, "\\x%02x", c & 0xff);
		else
			fputc(c, fp);
	}
	fputc(quote, fp);
	return 0;
}

PyObject *
PyString_Repr(PyObject *obj, int smartquotes)
{
	static const char *hexdigits = "0123456789abcdef";
	register PyStringObject* op = (PyStringObject*) obj;
	Py_ssize_t length = PyString_GET_SIZE(op);
	size_t newsize = 2 + 4 * op->ob_size;
	PyObject *v;
	if (newsize > PY_SSIZE_T_MAX || newsize / 4 != op->ob_size) {
		PyErr_SetString(PyExc_OverflowError,
			"string is too large to make repr");
	}
	v = PyUnicode_FromUnicode(NULL, newsize);
	if (v == NULL) {
		return NULL;
	}
	else {
		register Py_ssize_t i;
		register Py_UNICODE c;
		register Py_UNICODE *p = PyUnicode_AS_UNICODE(v);
		int quote;

		/* figure out which quote to use; single is preferred */
		quote = '\'';
		if (smartquotes) {
			Py_UNICODE *test;
			for (test = p; test < p+length; ++test) {
				if (*test == '"') {
					quote = '\''; /* switch back to single quote */
					goto decided;
				}
				else if (*test == '\'')
					quote = '"';
			}
			decided:
			;
		}

		*p++ = quote;
		for (i = 0; i < op->ob_size; i++) {
			/* There's at least enough room for a hex escape
			   and a closing quote. */
			assert(newsize - (p - PyUnicode_AS_UNICODE(v)) >= 5);
			c = op->ob_sval[i];
			if (c == quote || c == '\\')
				*p++ = '\\', *p++ = c;
			else if (c == '\t')
				*p++ = '\\', *p++ = 't';
			else if (c == '\n')
				*p++ = '\\', *p++ = 'n';
			else if (c == '\r')
				*p++ = '\\', *p++ = 'r';
			else if (c < ' ' || c >= 0x7f) {
				*p++ = '\\';
				*p++ = 'x';
				*p++ = hexdigits[(c & 0xf0) >> 4];
				*p++ = hexdigits[c & 0xf];
			}
			else
				*p++ = c;
		}
		assert(newsize - (p - PyUnicode_AS_UNICODE(v)) >= 1);
		*p++ = quote;
		*p = '\0';
		if (PyUnicode_Resize(&v, (p - PyUnicode_AS_UNICODE(v)))) {
			Py_DECREF(v);
			return NULL;
		}
		return v;
	}
}

static PyObject *
string_repr(PyObject *op)
{
	return PyString_Repr(op, 1);
}

static PyObject *
string_str(PyObject *s)
{
	assert(PyString_Check(s));
	if (PyString_CheckExact(s)) {
		Py_INCREF(s);
		return s;
	}
	else {
		/* Subtype -- return genuine string with the same value. */
		PyStringObject *t = (PyStringObject *) s;
		return PyString_FromStringAndSize(t->ob_sval, t->ob_size);
	}
}

static Py_ssize_t
string_length(PyStringObject *a)
{
	return a->ob_size;
}

static PyObject *
string_concat(register PyStringObject *a, register PyObject *bb)
{
	register Py_ssize_t size;
	register PyStringObject *op;
	if (!PyString_Check(bb)) {
		if (PyUnicode_Check(bb))
		    return PyUnicode_Concat((PyObject *)a, bb);
                if (PyBytes_Check(bb))
			return PyBytes_Concat((PyObject *)a, bb);
		PyErr_Format(PyExc_TypeError,
			     "cannot concatenate 'str8' and '%.200s' objects",
			     bb->ob_type->tp_name);
		return NULL;
	}
#define b ((PyStringObject *)bb)
	/* Optimize cases with empty left or right operand */
	if ((a->ob_size == 0 || b->ob_size == 0) &&
	    PyString_CheckExact(a) && PyString_CheckExact(b)) {
		if (a->ob_size == 0) {
			Py_INCREF(bb);
			return bb;
		}
		Py_INCREF(a);
		return (PyObject *)a;
	}
	size = a->ob_size + b->ob_size;
	if (size < 0) {
		PyErr_SetString(PyExc_OverflowError,
				"strings are too large to concat");
		return NULL;
	}
	  
	/* Inline PyObject_NewVar */
	op = (PyStringObject *)PyObject_MALLOC(sizeof(PyStringObject) + size);
	if (op == NULL)
		return PyErr_NoMemory();
	PyObject_INIT_VAR(op, &PyString_Type, size);
	op->ob_shash = -1;
	op->ob_sstate = SSTATE_NOT_INTERNED;
	Py_MEMCPY(op->ob_sval, a->ob_sval, a->ob_size);
	Py_MEMCPY(op->ob_sval + a->ob_size, b->ob_sval, b->ob_size);
	op->ob_sval[size] = '\0';
	return (PyObject *) op;
#undef b
}

static PyObject *
string_repeat(register PyStringObject *a, register Py_ssize_t n)
{
	register Py_ssize_t i;
	register Py_ssize_t j;
	register Py_ssize_t size;
	register PyStringObject *op;
	size_t nbytes;
	if (n < 0)
		n = 0;
	/* watch out for overflows:  the size can overflow int,
	 * and the # of bytes needed can overflow size_t
	 */
	size = a->ob_size * n;
	if (n && size / n != a->ob_size) {
		PyErr_SetString(PyExc_OverflowError,
			"repeated string is too long");
		return NULL;
	}
	if (size == a->ob_size && PyString_CheckExact(a)) {
		Py_INCREF(a);
		return (PyObject *)a;
	}
	nbytes = (size_t)size;
	if (nbytes + sizeof(PyStringObject) <= nbytes) {
		PyErr_SetString(PyExc_OverflowError,
			"repeated string is too long");
		return NULL;
	}
	op = (PyStringObject *)
		PyObject_MALLOC(sizeof(PyStringObject) + nbytes);
	if (op == NULL)
		return PyErr_NoMemory();
	PyObject_INIT_VAR(op, &PyString_Type, size);
	op->ob_shash = -1;
	op->ob_sstate = SSTATE_NOT_INTERNED;
	op->ob_sval[size] = '\0';
	if (a->ob_size == 1 && n > 0) {
		memset(op->ob_sval, a->ob_sval[0] , n);
		return (PyObject *) op;
	}
	i = 0;
	if (i < size) {
		Py_MEMCPY(op->ob_sval, a->ob_sval, a->ob_size);
		i = a->ob_size;
	}
	while (i < size) {
		j = (i <= size-i)  ?  i  :  size-i;
		Py_MEMCPY(op->ob_sval+i, op->ob_sval, j);
		i += j;
	}
	return (PyObject *) op;
}

/* String slice a[i:j] consists of characters a[i] ... a[j-1] */

static PyObject *
string_slice(register PyStringObject *a, register Py_ssize_t i,
	     register Py_ssize_t j)
     /* j -- may be negative! */
{
	if (i < 0)
		i = 0;
	if (j < 0)
		j = 0; /* Avoid signed/unsigned bug in next line */
	if (j > a->ob_size)
		j = a->ob_size;
	if (i == 0 && j == a->ob_size && PyString_CheckExact(a)) {
		/* It's the same as a */
		Py_INCREF(a);
		return (PyObject *)a;
	}
	if (j < i)
		j = i;
	return PyString_FromStringAndSize(a->ob_sval + i, j-i);
}

static int
string_contains(PyObject *str_obj, PyObject *sub_obj)
{
	if (!PyString_CheckExact(sub_obj)) {
		if (PyUnicode_Check(sub_obj))
			return PyUnicode_Contains(str_obj, sub_obj);
		if (!PyString_Check(sub_obj)) {
			PyErr_Format(PyExc_TypeError,
			    "'in <string>' requires string as left operand, "
			    "not %.200s", sub_obj->ob_type->tp_name);
			return -1;
		}
	}

	return stringlib_contains_obj(str_obj, sub_obj);
}

static PyObject *
string_item(PyStringObject *a, register Py_ssize_t i)
{
	char pchar;
	PyObject *v;
	if (i < 0 || i >= a->ob_size) {
		PyErr_SetString(PyExc_IndexError, "string index out of range");
		return NULL;
	}
	pchar = a->ob_sval[i];
	v = (PyObject *)characters[pchar & UCHAR_MAX];
	if (v == NULL)
		v = PyString_FromStringAndSize(&pchar, 1);
	else {
#ifdef COUNT_ALLOCS
		one_strings++;
#endif
		Py_INCREF(v);
	}
	return v;
}

static PyObject*
string_richcompare(PyStringObject *a, PyStringObject *b, int op)
{
	int c;
	Py_ssize_t len_a, len_b;
	Py_ssize_t min_len;
	PyObject *result;

	/* Make sure both arguments are strings. */
	if (!(PyString_Check(a) && PyString_Check(b))) {
		result = Py_NotImplemented;
		goto out;
	}
	if (a == b) {
		switch (op) {
		case Py_EQ:case Py_LE:case Py_GE:
			result = Py_True;
			goto out;
		case Py_NE:case Py_LT:case Py_GT:
			result = Py_False;
			goto out;
		}
	}
	if (op == Py_EQ) {
		/* Supporting Py_NE here as well does not save
		   much time, since Py_NE is rarely used.  */
		if (a->ob_size == b->ob_size
		    && (a->ob_sval[0] == b->ob_sval[0]
			&& memcmp(a->ob_sval, b->ob_sval, a->ob_size) == 0)) {
			result = Py_True;
		} else {
			result = Py_False;
		}
		goto out;
	}
	len_a = a->ob_size; len_b = b->ob_size;
	min_len = (len_a < len_b) ? len_a : len_b;
	if (min_len > 0) {
		c = Py_CHARMASK(*a->ob_sval) - Py_CHARMASK(*b->ob_sval);
		if (c==0)
			c = memcmp(a->ob_sval, b->ob_sval, min_len);
	} else
		c = 0;
	if (c == 0)
		c = (len_a < len_b) ? -1 : (len_a > len_b) ? 1 : 0;
	switch (op) {
	case Py_LT: c = c <  0; break;
	case Py_LE: c = c <= 0; break;
	case Py_EQ: assert(0);  break; /* unreachable */
	case Py_NE: c = c != 0; break;
	case Py_GT: c = c >  0; break;
	case Py_GE: c = c >= 0; break;
	default:
		result = Py_NotImplemented;
		goto out;
	}
	result = c ? Py_True : Py_False;
  out:
	Py_INCREF(result);
	return result;
}

int
_PyString_Eq(PyObject *o1, PyObject *o2)
{
	PyStringObject *a = (PyStringObject*) o1;
	PyStringObject *b = (PyStringObject*) o2;
        return a->ob_size == b->ob_size
          && *a->ob_sval == *b->ob_sval
          && memcmp(a->ob_sval, b->ob_sval, a->ob_size) == 0;
}

static long
string_hash(PyStringObject *a)
{
	register Py_ssize_t len;
	register unsigned char *p;
	register long x;

	if (a->ob_shash != -1)
		return a->ob_shash;
	len = a->ob_size;
	p = (unsigned char *) a->ob_sval;
	x = *p << 7;
	while (--len >= 0)
		x = (1000003*x) ^ *p++;
	x ^= a->ob_size;
	if (x == -1)
		x = -2;
	a->ob_shash = x;
	return x;
}

static PyObject*
string_subscript(PyStringObject* self, PyObject* item)
{
	if (PyIndex_Check(item)) {
		Py_ssize_t i = PyNumber_AsSsize_t(item, PyExc_IndexError);
		if (i == -1 && PyErr_Occurred())
			return NULL;
		if (i < 0)
			i += PyString_GET_SIZE(self);
		return string_item(self, i);
	}
	else if (PySlice_Check(item)) {
		Py_ssize_t start, stop, step, slicelength, cur, i;
		char* source_buf;
		char* result_buf;
		PyObject* result;

		if (PySlice_GetIndicesEx((PySliceObject*)item,
				 PyString_GET_SIZE(self),
				 &start, &stop, &step, &slicelength) < 0) {
			return NULL;
		}

		if (slicelength <= 0) {
			return PyString_FromStringAndSize("", 0);
		}
		else {
			source_buf = PyString_AsString((PyObject*)self);
			result_buf = (char *)PyMem_Malloc(slicelength);
			if (result_buf == NULL)
				return PyErr_NoMemory();

			for (cur = start, i = 0; i < slicelength;
			     cur += step, i++) {
				result_buf[i] = source_buf[cur];
			}

			result = PyString_FromStringAndSize(result_buf,
							    slicelength);
			PyMem_Free(result_buf);
			return result;
		}
	}
	else {
		PyErr_Format(PyExc_TypeError,
			     "string indices must be integers, not %.200s",
			     item->ob_type->tp_name);
		return NULL;
	}
}

static Py_ssize_t
string_buffer_getreadbuf(PyStringObject *self, Py_ssize_t index, const void **ptr)
{
	if ( index != 0 ) {
		PyErr_SetString(PyExc_SystemError,
				"accessing non-existent string segment");
		return -1;
	}
	*ptr = (void *)self->ob_sval;
	return self->ob_size;
}

static Py_ssize_t
string_buffer_getwritebuf(PyStringObject *self, Py_ssize_t index, const void **ptr)
{
	PyErr_SetString(PyExc_TypeError,
			"Cannot use string as modifiable buffer");
	return -1;
}

static Py_ssize_t
string_buffer_getsegcount(PyStringObject *self, Py_ssize_t *lenp)
{
	if ( lenp )
		*lenp = self->ob_size;
	return 1;
}

static Py_ssize_t
string_buffer_getcharbuf(PyStringObject *self, Py_ssize_t index, const char **ptr)
{
	if ( index != 0 ) {
		PyErr_SetString(PyExc_SystemError,
				"accessing non-existent string segment");
		return -1;
	}
	*ptr = self->ob_sval;
	return self->ob_size;
}

static PySequenceMethods string_as_sequence = {
	(lenfunc)string_length, /*sq_length*/
	(binaryfunc)string_concat, /*sq_concat*/
	(ssizeargfunc)string_repeat, /*sq_repeat*/
	(ssizeargfunc)string_item, /*sq_item*/
	(ssizessizeargfunc)string_slice, /*sq_slice*/
	0,		/*sq_ass_item*/
	0,		/*sq_ass_slice*/
	(objobjproc)string_contains /*sq_contains*/
};

static PyMappingMethods string_as_mapping = {
	(lenfunc)string_length,
	(binaryfunc)string_subscript,
	0,
};

static PyBufferProcs string_as_buffer = {
	(readbufferproc)string_buffer_getreadbuf,
	(writebufferproc)string_buffer_getwritebuf,
	(segcountproc)string_buffer_getsegcount,
	(charbufferproc)string_buffer_getcharbuf,
};



#define LEFTSTRIP 0
#define RIGHTSTRIP 1
#define BOTHSTRIP 2

/* Arrays indexed by above */
static const char *stripformat[] = {"|O:lstrip", "|O:rstrip", "|O:strip"};

#define STRIPNAME(i) (stripformat[i]+3)


/* Don't call if length < 2 */
#define Py_STRING_MATCH(target, offset, pattern, length)	\
  (target[offset] == pattern[0] &&				\
   target[offset+length-1] == pattern[length-1] &&		\
   !memcmp(target+offset+1, pattern+1, length-2) )


/* Overallocate the initial list to reduce the number of reallocs for small
   split sizes.  Eg, "A A A A A A A A A A".split() (10 elements) has three
   resizes, to sizes 4, 8, then 16.  Most observed string splits are for human
   text (roughly 11 words per line) and field delimited data (usually 1-10
   fields).  For large strings the split algorithms are bandwidth limited
   so increasing the preallocation likely will not improve things.*/

#define MAX_PREALLOC 12

/* 5 splits gives 6 elements */
#define PREALLOC_SIZE(maxsplit) \
	(maxsplit >= MAX_PREALLOC ? MAX_PREALLOC : maxsplit+1)

#define SPLIT_APPEND(data, left, right)				\
	str = PyString_FromStringAndSize((data) + (left),	\
					 (right) - (left));	\
	if (str == NULL)					\
		goto onError;					\
	if (PyList_Append(list, str)) {				\
		Py_DECREF(str);					\
		goto onError;					\
	}							\
	else							\
		Py_DECREF(str);

#define SPLIT_ADD(data, left, right) {				\
	str = PyString_FromStringAndSize((data) + (left),	\
					 (right) - (left));	\
	if (str == NULL)					\
		goto onError;					\
	if (count < MAX_PREALLOC) {				\
		PyList_SET_ITEM(list, count, str);		\
	} else {						\
		if (PyList_Append(list, str)) {			\
			Py_DECREF(str);				\
			goto onError;				\
		}						\
		else						\
			Py_DECREF(str);				\
	}							\
	count++; }

/* Always force the list to the expected size. */
#define FIX_PREALLOC_SIZE(list) ((PyListObject *)list)->ob_size = count

#define SKIP_SPACE(s, i, len)    { while (i<len &&  isspace(Py_CHARMASK(s[i]))) i++; }
#define SKIP_NONSPACE(s, i, len) { while (i<len && !isspace(Py_CHARMASK(s[i]))) i++; }
#define RSKIP_SPACE(s, i)        { while (i>=0  &&  isspace(Py_CHARMASK(s[i]))) i--; }
#define RSKIP_NONSPACE(s, i)     { while (i>=0  && !isspace(Py_CHARMASK(s[i]))) i--; }

Py_LOCAL_INLINE(PyObject *)
split_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
{
	Py_ssize_t i, j, count=0;
	PyObject *str;
	PyObject *list = PyList_New(PREALLOC_SIZE(maxsplit));

	if (list == NULL)
		return NULL;

	i = j = 0;

	while (maxsplit-- > 0) {
		SKIP_SPACE(s, i, len);
		if (i==len) break;
		j = i; i++;
		SKIP_NONSPACE(s, i, len);
		SPLIT_ADD(s, j, i);
	}

	if (i < len) {
		/* Only occurs when maxsplit was reached */
		/* Skip any remaining whitespace and copy to end of string */
		SKIP_SPACE(s, i, len);
		if (i != len)
			SPLIT_ADD(s, i, len);
	}
	FIX_PREALLOC_SIZE(list);
	return list;
  onError:
	Py_DECREF(list);
	return NULL;
}

Py_LOCAL_INLINE(PyObject *)
split_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
{
	register Py_ssize_t i, j, count=0;
	PyObject *str;
	PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));

	if (list == NULL)
		return NULL;

	i = j = 0;
	while ((j < len) && (maxcount-- > 0)) {
		for(; j<len; j++) {
			/* I found that using memchr makes no difference */
			if (s[j] == ch) {
				SPLIT_ADD(s, i, j);
				i = j = j + 1;
				break;
			}
		}
	}
	if (i <= len) {
		SPLIT_ADD(s, i, len);
	}
	FIX_PREALLOC_SIZE(list);
	return list;

  onError:
	Py_DECREF(list);
	return NULL;
}

PyDoc_STRVAR(split__doc__,
"S.split([sep [,maxsplit]]) -> list of strings\n\
\n\
Return a list of the words in the string S, using sep as the\n\
delimiter string.  If maxsplit is given, at most maxsplit\n\
splits are done. If sep is not specified or is None, any\n\
whitespace string is a separator.");

static PyObject *
string_split(PyStringObject *self, PyObject *args)
{
	Py_ssize_t len = PyString_GET_SIZE(self), n, i, j;
	Py_ssize_t maxsplit = -1, count=0;
	const char *s = PyString_AS_STRING(self), *sub;
	PyObject *list, *str, *subobj = Py_None;
#ifdef USE_FAST
	Py_ssize_t pos;
#endif

	if (!PyArg_ParseTuple(args, "|On:split", &subobj, &maxsplit))
		return NULL;
	if (maxsplit < 0)
		maxsplit = PY_SSIZE_T_MAX;
	if (subobj == Py_None)
		return split_whitespace(s, len, maxsplit);
	if (PyString_Check(subobj)) {
		sub = PyString_AS_STRING(subobj);
		n = PyString_GET_SIZE(subobj);
	}
	else if (PyUnicode_Check(subobj))
		return PyUnicode_Split((PyObject *)self, subobj, maxsplit);
	else if (PyObject_AsCharBuffer(subobj, &sub, &n))
		return NULL;

	if (n == 0) {
		PyErr_SetString(PyExc_ValueError, "empty separator");
		return NULL;
	}
	else if (n == 1)
		return split_char(s, len, sub[0], maxsplit);

	list = PyList_New(PREALLOC_SIZE(maxsplit));
	if (list == NULL)
		return NULL;

#ifdef USE_FAST
	i = j = 0;
	while (maxsplit-- > 0) {
		pos = fastsearch(s+i, len-i, sub, n, FAST_SEARCH);
		if (pos < 0)
			break;
		j = i+pos;
		SPLIT_ADD(s, i, j);
		i = j + n;
	}
#else
	i = j = 0;
	while ((j+n <= len) && (maxsplit-- > 0)) {
		for (; j+n <= len; j++) {
			if (Py_STRING_MATCH(s, j, sub, n)) {
				SPLIT_ADD(s, i, j);
				i = j = j + n;
				break;
			}
		}
	}
#endif
	SPLIT_ADD(s, i, len);
	FIX_PREALLOC_SIZE(list);
	return list;

 onError:
	Py_DECREF(list);
	return NULL;
}

PyDoc_STRVAR(partition__doc__,
"S.partition(sep) -> (head, sep, tail)\n\
\n\
Searches for the separator sep in S, and returns the part before it,\n\
the separator itself, and the part after it.  If the separator is not\n\
found, returns S and two empty strings.");

static PyObject *
string_partition(PyStringObject *self, PyObject *sep_obj)
{
	const char *sep;
	Py_ssize_t sep_len;

	if (PyString_Check(sep_obj)) {
		sep = PyString_AS_STRING(sep_obj);
		sep_len = PyString_GET_SIZE(sep_obj);
	}
	else if (PyUnicode_Check(sep_obj))
		return PyUnicode_Partition((PyObject *) self, sep_obj);
	else if (PyObject_AsCharBuffer(sep_obj, &sep, &sep_len))
		return NULL;

	return stringlib_partition(
		(PyObject*) self,
		PyString_AS_STRING(self), PyString_GET_SIZE(self),
		sep_obj, sep, sep_len
		);
}

PyDoc_STRVAR(rpartition__doc__,
"S.rpartition(sep) -> (tail, sep, head)\n\
\n\
Searches for the separator sep in S, starting at the end of S, and returns\n\
the part before it, the separator itself, and the part after it.  If the\n\
separator is not found, returns two empty strings and S.");

static PyObject *
string_rpartition(PyStringObject *self, PyObject *sep_obj)
{
	const char *sep;
	Py_ssize_t sep_len;

	if (PyString_Check(sep_obj)) {
		sep = PyString_AS_STRING(sep_obj);
		sep_len = PyString_GET_SIZE(sep_obj);
	}
	else if (PyUnicode_Check(sep_obj))
		return PyUnicode_Partition((PyObject *) self, sep_obj);
	else if (PyObject_AsCharBuffer(sep_obj, &sep, &sep_len))
		return NULL;

	return stringlib_rpartition(
		(PyObject*) self,
		PyString_AS_STRING(self), PyString_GET_SIZE(self),
		sep_obj, sep, sep_len
		);
}

Py_LOCAL_INLINE(PyObject *)
rsplit_whitespace(const char *s, Py_ssize_t len, Py_ssize_t maxsplit)
{
	Py_ssize_t i, j, count=0;
	PyObject *str;
	PyObject *list = PyList_New(PREALLOC_SIZE(maxsplit));

	if (list == NULL)
		return NULL;

	i = j = len-1;

	while (maxsplit-- > 0) {
		RSKIP_SPACE(s, i);
		if (i<0) break;
		j = i; i--;
		RSKIP_NONSPACE(s, i);
		SPLIT_ADD(s, i + 1, j + 1);
	}
	if (i >= 0) {
		/* Only occurs when maxsplit was reached */
		/* Skip any remaining whitespace and copy to beginning of string */
		RSKIP_SPACE(s, i);
		if (i >= 0)
			SPLIT_ADD(s, 0, i + 1);

	}
	FIX_PREALLOC_SIZE(list);
	if (PyList_Reverse(list) < 0)
		goto onError;
	return list;
  onError:
	Py_DECREF(list);
	return NULL;
}

Py_LOCAL_INLINE(PyObject *)
rsplit_char(const char *s, Py_ssize_t len, char ch, Py_ssize_t maxcount)
{
	register Py_ssize_t i, j, count=0;
	PyObject *str;
	PyObject *list = PyList_New(PREALLOC_SIZE(maxcount));

	if (list == NULL)
		return NULL;

	i = j = len - 1;
	while ((i >= 0) && (maxcount-- > 0)) {
		for (; i >= 0; i--) {
			if (s[i] == ch) {
				SPLIT_ADD(s, i + 1, j + 1);
				j = i = i - 1;
				break;
			}
		}
	}
	if (j >= -1) {
		SPLIT_ADD(s, 0, j + 1);
	}
	FIX_PREALLOC_SIZE(list);
	if (PyList_Reverse(list) < 0)
		goto onError;
	return list;

 onError:
	Py_DECREF(list);
	return NULL;
}

PyDoc_STRVAR(rsplit__doc__,
"S.rsplit([sep [,maxsplit]]) -> list of strings\n\
\n\
Return a list of the words in the string S, using sep as the\n\
delimiter string, starting at the end of the string and working\n\
to the front.  If maxsplit is given, at most maxsplit splits are\n\
done. If sep is not specified or is None, any whitespace string\n\
is a separator.");

static PyObject *
string_rsplit(PyStringObject *self, PyObject *args)
{
	Py_ssize_t len = PyString_GET_SIZE(self), n, i, j;
	Py_ssize_t maxsplit = -1, count=0;
	const char *s = PyString_AS_STRING(self), *sub;
	PyObject *list, *str, *subobj = Py_None;

	if (!PyArg_ParseTuple(args, "|On:rsplit", &subobj, &maxsplit))
		return NULL;
	if (maxsplit < 0)
		maxsplit = PY_SSIZE_T_MAX;
	if (subobj == Py_None)
		return rsplit_whitespace(s, len, maxsplit);
	if (PyString_Check(subobj)) {
		sub = PyString_AS_STRING(subobj);
		n = PyString_GET_SIZE(subobj);
	}
	else if (PyUnicode_Check(subobj))
		return PyUnicode_RSplit((PyObject *)self, subobj, maxsplit);
	else if (PyObject_AsCharBuffer(subobj, &sub, &n))
		return NULL;

	if (n == 0) {
		PyErr_SetString(PyExc_ValueError, "empty separator");
		return NULL;
	}
	else if (n == 1)
		return rsplit_char(s, len, sub[0], maxsplit);

	list = PyList_New(PREALLOC_SIZE(maxsplit));
	if (list == NULL)
		return NULL;

	j = len;
	i = j - n;

	while ( (i >= 0) && (maxsplit-- > 0) ) {
		for (; i>=0; i--) {
			if (Py_STRING_MATCH(s, i, sub, n)) {
				SPLIT_ADD(s, i + n, j);
				j = i;
				i -= n;
				break;
			}
		}
	}
	SPLIT_ADD(s, 0, j);
	FIX_PREALLOC_SIZE(list);
	if (PyList_Reverse(list) < 0)
		goto onError;
	return list;

onError:
	Py_DECREF(list);
	return NULL;
}


PyDoc_STRVAR(join__doc__,
"S.join(sequence) -> string\n\
\n\
Return a string which is the concatenation of the strings in the\n\
sequence.  The separator between elements is S.");

static PyObject *
string_join(PyStringObject *self, PyObject *orig)
{
	char *sep = PyString_AS_STRING(self);
	const Py_ssize_t seplen = PyString_GET_SIZE(self);
	PyObject *res = NULL;
	char *p;
	Py_ssize_t seqlen = 0;
	size_t sz = 0;
	Py_ssize_t i;
	PyObject *seq, *item;

	seq = PySequence_Fast(orig, "");
	if (seq == NULL) {
		return NULL;
	}

	seqlen = PySequence_Size(seq);
	if (seqlen == 0) {
		Py_DECREF(seq);
		return PyString_FromString("");
	}
	if (seqlen == 1) {
		item = PySequence_Fast_GET_ITEM(seq, 0);
		if (PyString_CheckExact(item) || PyUnicode_CheckExact(item)) {
			Py_INCREF(item);
			Py_DECREF(seq);
			return item;
		}
	}

	/* There are at least two things to join, or else we have a subclass
	 * of the builtin types in the sequence.
	 * Do a pre-pass to figure out the total amount of space we'll
	 * need (sz), see whether any argument is absurd, and defer to
	 * the Unicode join if appropriate.
	 */
	for (i = 0; i < seqlen; i++) {
		const size_t old_sz = sz;
		item = PySequence_Fast_GET_ITEM(seq, i);
		if (!PyString_Check(item)){
			if (PyUnicode_Check(item)) {
				/* Defer to Unicode join.
				 * CAUTION:  There's no gurantee that the
				 * original sequence can be iterated over
				 * again, so we must pass seq here.
				 */
				PyObject *result;
				result = PyUnicode_Join((PyObject *)self, seq);
				Py_DECREF(seq);
				return result;
			}
			PyErr_Format(PyExc_TypeError,
				     "sequence item %zd: expected string,"
				     " %.80s found",
				     i, item->ob_type->tp_name);
			Py_DECREF(seq);
			return NULL;
		}
		sz += PyString_GET_SIZE(item);
		if (i != 0)
			sz += seplen;
		if (sz < old_sz || sz > PY_SSIZE_T_MAX) {
			PyErr_SetString(PyExc_OverflowError,
				"join() result is too long for a Python string");
			Py_DECREF(seq);
			return NULL;
		}
	}

	/* Allocate result space. */
	res = PyString_FromStringAndSize((char*)NULL, sz);
	if (res == NULL) {
		Py_DECREF(seq);
		return NULL;
	}

	/* Catenate everything. */
	p = PyString_AS_STRING(res);
	for (i = 0; i < seqlen; ++i) {
		size_t n;
		item = PySequence_Fast_GET_ITEM(seq, i);
		n = PyString_GET_SIZE(item);
		Py_MEMCPY(p, PyString_AS_STRING(item), n);
		p += n;
		if (i < seqlen - 1) {
			Py_MEMCPY(p, sep, seplen);
			p += seplen;
		}
	}

	Py_DECREF(seq);
	return res;
}

PyObject *
_PyString_Join(PyObject *sep, PyObject *x)
{
	assert(sep != NULL && PyString_Check(sep));
	assert(x != NULL);
	return string_join((PyStringObject *)sep, x);
}

Py_LOCAL_INLINE(void)
string_adjust_indices(Py_ssize_t *start, Py_ssize_t *end, Py_ssize_t len)
{
	if (*end > len)
		*end = len;
	else if (*end < 0)
		*end += len;
	if (*end < 0)
		*end = 0;
	if (*start < 0)
		*start += len;
	if (*start < 0)
		*start = 0;
}

Py_LOCAL_INLINE(Py_ssize_t)
string_find_internal(PyStringObject *self, PyObject *args, int dir)
{
	PyObject *subobj;
	const char *sub;
	Py_ssize_t sub_len;
	Py_ssize_t start=0, end=PY_SSIZE_T_MAX;

	if (!PyArg_ParseTuple(args, "O|O&O&:find/rfind/index/rindex", &subobj,
		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
		return -2;
	if (PyString_Check(subobj)) {
		sub = PyString_AS_STRING(subobj);
		sub_len = PyString_GET_SIZE(subobj);
	}
	else if (PyUnicode_Check(subobj))
		return PyUnicode_Find(
			(PyObject *)self, subobj, start, end, dir);
	else if (PyObject_AsCharBuffer(subobj, &sub, &sub_len))
		/* XXX - the "expected a character buffer object" is pretty
		   confusing for a non-expert.  remap to something else ? */
		return -2;

	if (dir > 0)
		return stringlib_find_slice(
			PyString_AS_STRING(self), PyString_GET_SIZE(self),
			sub, sub_len, start, end);
	else
		return stringlib_rfind_slice(
			PyString_AS_STRING(self), PyString_GET_SIZE(self),
			sub, sub_len, start, end);
}


PyDoc_STRVAR(find__doc__,
"S.find(sub [,start [,end]]) -> int\n\
\n\
Return the lowest index in S where substring sub is found,\n\
such that sub is contained within s[start,end].  Optional\n\
arguments start and end are interpreted as in slice notation.\n\
\n\
Return -1 on failure.");

static PyObject *
string_find(PyStringObject *self, PyObject *args)
{
	Py_ssize_t result = string_find_internal(self, args, +1);
	if (result == -2)
		return NULL;
	return PyInt_FromSsize_t(result);
}


PyDoc_STRVAR(index__doc__,
"S.index(sub [,start [,end]]) -> int\n\
\n\
Like S.find() but raise ValueError when the substring is not found.");

static PyObject *
string_index(PyStringObject *self, PyObject *args)
{
	Py_ssize_t result = string_find_internal(self, args, +1);
	if (result == -2)
		return NULL;
	if (result == -1) {
		PyErr_SetString(PyExc_ValueError,
				"substring not found");
		return NULL;
	}
	return PyInt_FromSsize_t(result);
}


PyDoc_STRVAR(rfind__doc__,
"S.rfind(sub [,start [,end]]) -> int\n\
\n\
Return the highest index in S where substring sub is found,\n\
such that sub is contained within s[start,end].  Optional\n\
arguments start and end are interpreted as in slice notation.\n\
\n\
Return -1 on failure.");

static PyObject *
string_rfind(PyStringObject *self, PyObject *args)
{
	Py_ssize_t result = string_find_internal(self, args, -1);
	if (result == -2)
		return NULL;
	return PyInt_FromSsize_t(result);
}


PyDoc_STRVAR(rindex__doc__,
"S.rindex(sub [,start [,end]]) -> int\n\
\n\
Like S.rfind() but raise ValueError when the substring is not found.");

static PyObject *
string_rindex(PyStringObject *self, PyObject *args)
{
	Py_ssize_t result = string_find_internal(self, args, -1);
	if (result == -2)
		return NULL;
	if (result == -1) {
		PyErr_SetString(PyExc_ValueError,
				"substring not found");
		return NULL;
	}
	return PyInt_FromSsize_t(result);
}


Py_LOCAL_INLINE(PyObject *)
do_xstrip(PyStringObject *self, int striptype, PyObject *sepobj)
{
	char *s = PyString_AS_STRING(self);
	Py_ssize_t len = PyString_GET_SIZE(self);
	char *sep = PyString_AS_STRING(sepobj);
	Py_ssize_t seplen = PyString_GET_SIZE(sepobj);
	Py_ssize_t i, j;

	i = 0;
	if (striptype != RIGHTSTRIP) {
		while (i < len && memchr(sep, Py_CHARMASK(s[i]), seplen)) {
			i++;
		}
	}

	j = len;
	if (striptype != LEFTSTRIP) {
		do {
			j--;
		} while (j >= i && memchr(sep, Py_CHARMASK(s[j]), seplen));
		j++;
	}

	if (i == 0 && j == len && PyString_CheckExact(self)) {
		Py_INCREF(self);
		return (PyObject*)self;
	}
	else
		return PyString_FromStringAndSize(s+i, j-i);
}


Py_LOCAL_INLINE(PyObject *)
do_strip(PyStringObject *self, int striptype)
{
	char *s = PyString_AS_STRING(self);
	Py_ssize_t len = PyString_GET_SIZE(self), i, j;

	i = 0;
	if (striptype != RIGHTSTRIP) {
		while (i < len && isspace(Py_CHARMASK(s[i]))) {
			i++;
		}
	}

	j = len;
	if (striptype != LEFTSTRIP) {
		do {
			j--;
		} while (j >= i && isspace(Py_CHARMASK(s[j])));
		j++;
	}

	if (i == 0 && j == len && PyString_CheckExact(self)) {
		Py_INCREF(self);
		return (PyObject*)self;
	}
	else
		return PyString_FromStringAndSize(s+i, j-i);
}


Py_LOCAL_INLINE(PyObject *)
do_argstrip(PyStringObject *self, int striptype, PyObject *args)
{
	PyObject *sep = NULL;

	if (!PyArg_ParseTuple(args, (char *)stripformat[striptype], &sep))
		return NULL;

	if (sep != NULL && sep != Py_None) {
		if (PyString_Check(sep))
			return do_xstrip(self, striptype, sep);
		else if (PyUnicode_Check(sep)) {
			PyObject *uniself = PyUnicode_FromObject((PyObject *)self);
			PyObject *res;
			if (uniself==NULL)
				return NULL;
			res = _PyUnicode_XStrip((PyUnicodeObject *)uniself,
				striptype, sep);
			Py_DECREF(uniself);
			return res;
		}
		PyErr_Format(PyExc_TypeError,
			     "%s arg must be None or string",
			     STRIPNAME(striptype));
		return NULL;
	}

	return do_strip(self, striptype);
}


PyDoc_STRVAR(strip__doc__,
"S.strip([chars]) -> string\n\
\n\
Return a copy of the string S with leading and trailing\n\
whitespace removed.\n\
If chars is given and not None, remove characters in chars instead.\n\
If chars is unicode, S will be converted to unicode before stripping");

static PyObject *
string_strip(PyStringObject *self, PyObject *args)
{
	if (PyTuple_GET_SIZE(args) == 0)
		return do_strip(self, BOTHSTRIP); /* Common case */
	else
		return do_argstrip(self, BOTHSTRIP, args);
}


PyDoc_STRVAR(lstrip__doc__,
"S.lstrip([chars]) -> string\n\
\n\
Return a copy of the string S with leading whitespace removed.\n\
If chars is given and not None, remove characters in chars instead.\n\
If chars is unicode, S will be converted to unicode before stripping");

static PyObject *
string_lstrip(PyStringObject *self, PyObject *args)
{
	if (PyTuple_GET_SIZE(args) == 0)
		return do_strip(self, LEFTSTRIP); /* Common case */
	else
		return do_argstrip(self, LEFTSTRIP, args);
}


PyDoc_STRVAR(rstrip__doc__,
"S.rstrip([chars]) -> string\n\
\n\
Return a copy of the string S with trailing whitespace removed.\n\
If chars is given and not None, remove characters in chars instead.\n\
If chars is unicode, S will be converted to unicode before stripping");

static PyObject *
string_rstrip(PyStringObject *self, PyObject *args)
{
	if (PyTuple_GET_SIZE(args) == 0)
		return do_strip(self, RIGHTSTRIP); /* Common case */
	else
		return do_argstrip(self, RIGHTSTRIP, args);
}


PyDoc_STRVAR(lower__doc__,
"S.lower() -> string\n\
\n\
Return a copy of the string S converted to lowercase.");

/* _tolower and _toupper are defined by SUSv2, but they're not ISO C */
#ifndef _tolower
#define _tolower tolower
#endif

static PyObject *
string_lower(PyStringObject *self)
{
	char *s;
	Py_ssize_t i, n = PyString_GET_SIZE(self);
	PyObject *newobj;

	newobj = PyString_FromStringAndSize(NULL, n);
	if (!newobj)
		return NULL;

	s = PyString_AS_STRING(newobj);

	Py_MEMCPY(s, PyString_AS_STRING(self), n);

	for (i = 0; i < n; i++) {
		int c = Py_CHARMASK(s[i]);
		if (isupper(c))
			s[i] = _tolower(c);
	}

	return newobj;
}

PyDoc_STRVAR(upper__doc__,
"S.upper() -> string\n\
\n\
Return a copy of the string S converted to uppercase.");

#ifndef _toupper
#define _toupper toupper
#endif

static PyObject *
string_upper(PyStringObject *self)
{
	char *s;
	Py_ssize_t i, n = PyString_GET_SIZE(self);
	PyObject *newobj;

	newobj = PyString_FromStringAndSize(NULL, n);
	if (!newobj)
		return NULL;

	s = PyString_AS_STRING(newobj);

	Py_MEMCPY(s, PyString_AS_STRING(self), n);

	for (i = 0; i < n; i++) {
		int c = Py_CHARMASK(s[i]);
		if (islower(c))
			s[i] = _toupper(c);
	}

	return newobj;
}

PyDoc_STRVAR(title__doc__,
"S.title() -> string\n\
\n\
Return a titlecased version of S, i.e. words start with uppercase\n\
characters, all remaining cased characters have lowercase.");

static PyObject*
string_title(PyStringObject *self)
{
	char *s = PyString_AS_STRING(self), *s_new;
	Py_ssize_t i, n = PyString_GET_SIZE(self);
	int previous_is_cased = 0;
	PyObject *newobj;

	newobj = PyString_FromStringAndSize(NULL, n);
	if (newobj == NULL)
		return NULL;
	s_new = PyString_AsString(newobj);
	for (i = 0; i < n; i++) {
		int c = Py_CHARMASK(*s++);
		if (islower(c)) {
			if (!previous_is_cased)
			    c = toupper(c);
			previous_is_cased = 1;
		} else if (isupper(c)) {
			if (previous_is_cased)
			    c = tolower(c);
			previous_is_cased = 1;
		} else
			previous_is_cased = 0;
		*s_new++ = c;
	}
	return newobj;
}

PyDoc_STRVAR(capitalize__doc__,
"S.capitalize() -> string\n\
\n\
Return a copy of the string S with only its first character\n\
capitalized.");

static PyObject *
string_capitalize(PyStringObject *self)
{
	char *s = PyString_AS_STRING(self), *s_new;
	Py_ssize_t i, n = PyString_GET_SIZE(self);
	PyObject *newobj;

	newobj = PyString_FromStringAndSize(NULL, n);
	if (newobj == NULL)
		return NULL;
	s_new = PyString_AsString(newobj);
	if (0 < n) {
		int c = Py_CHARMASK(*s++);
		if (islower(c))
			*s_new = toupper(c);
		else
			*s_new = c;
		s_new++;
	}
	for (i = 1; i < n; i++) {
		int c = Py_CHARMASK(*s++);
		if (isupper(c))
			*s_new = tolower(c);
		else
			*s_new = c;
		s_new++;
	}
	return newobj;
}


PyDoc_STRVAR(count__doc__,
"S.count(sub[, start[, end]]) -> int\n\
\n\
Return the number of non-overlapping occurrences of substring sub in\n\
string S[start:end].  Optional arguments start and end are interpreted\n\
as in slice notation.");

static PyObject *
string_count(PyStringObject *self, PyObject *args)
{
	PyObject *sub_obj;
	const char *str = PyString_AS_STRING(self), *sub;
	Py_ssize_t sub_len;
	Py_ssize_t start = 0, end = PY_SSIZE_T_MAX;

	if (!PyArg_ParseTuple(args, "O|O&O&:count", &sub_obj,
		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
		return NULL;

	if (PyString_Check(sub_obj)) {
		sub = PyString_AS_STRING(sub_obj);
		sub_len = PyString_GET_SIZE(sub_obj);
	}
	else if (PyUnicode_Check(sub_obj)) {
		Py_ssize_t count;
		count = PyUnicode_Count((PyObject *)self, sub_obj, start, end);
		if (count == -1)
			return NULL;
		else
		    	return PyInt_FromSsize_t(count);
	}
	else if (PyObject_AsCharBuffer(sub_obj, &sub, &sub_len))
		return NULL;

	string_adjust_indices(&start, &end, PyString_GET_SIZE(self));

	return PyInt_FromSsize_t(
		stringlib_count(str + start, end - start, sub, sub_len)
		);
}

PyDoc_STRVAR(swapcase__doc__,
"S.swapcase() -> string\n\
\n\
Return a copy of the string S with uppercase characters\n\
converted to lowercase and vice versa.");

static PyObject *
string_swapcase(PyStringObject *self)
{
	char *s = PyString_AS_STRING(self), *s_new;
	Py_ssize_t i, n = PyString_GET_SIZE(self);
	PyObject *newobj;

	newobj = PyString_FromStringAndSize(NULL, n);
	if (newobj == NULL)
		return NULL;
	s_new = PyString_AsString(newobj);
	for (i = 0; i < n; i++) {
		int c = Py_CHARMASK(*s++);
		if (islower(c)) {
			*s_new = toupper(c);
		}
		else if (isupper(c)) {
			*s_new = tolower(c);
		}
		else
			*s_new = c;
		s_new++;
	}
	return newobj;
}


PyDoc_STRVAR(translate__doc__,
"S.translate(table [,deletechars]) -> string\n\
\n\
Return a copy of the string S, where all characters occurring\n\
in the optional argument deletechars are removed, and the\n\
remaining characters have been mapped through the given\n\
translation table, which must be a string of length 256.");

static PyObject *
string_translate(PyStringObject *self, PyObject *args)
{
	register char *input, *output;
	const char *table;
	register Py_ssize_t i, c, changed = 0;
	PyObject *input_obj = (PyObject*)self;
	const char *output_start, *del_table=NULL;
	Py_ssize_t inlen, tablen, dellen = 0;
	PyObject *result;
	int trans_table[256];
	PyObject *tableobj, *delobj = NULL;

	if (!PyArg_UnpackTuple(args, "translate", 1, 2,
			      &tableobj, &delobj))
		return NULL;

	if (PyString_Check(tableobj)) {
		table = PyString_AS_STRING(tableobj);
		tablen = PyString_GET_SIZE(tableobj);
	}
	else if (tableobj == Py_None) {
		table = NULL;
		tablen = 256;
	}
	else if (PyUnicode_Check(tableobj)) {
		/* Unicode .translate() does not support the deletechars
		   parameter; instead a mapping to None will cause characters
		   to be deleted. */
		if (delobj != NULL) {
			PyErr_SetString(PyExc_TypeError,
			"deletions are implemented differently for unicode");
			return NULL;
		}
		return PyUnicode_Translate((PyObject *)self, tableobj, NULL);
	}
	else if (PyObject_AsCharBuffer(tableobj, &table, &tablen))
		return NULL;

	if (tablen != 256) {
		PyErr_SetString(PyExc_ValueError,
		  "translation table must be 256 characters long");
		return NULL;
	}

	if (delobj != NULL) {
		if (PyString_Check(delobj)) {
			del_table = PyString_AS_STRING(delobj);
			dellen = PyString_GET_SIZE(delobj);
		}
		else if (PyUnicode_Check(delobj)) {
			PyErr_SetString(PyExc_TypeError,
			"deletions are implemented differently for unicode");
			return NULL;
		}
		else if (PyObject_AsCharBuffer(delobj, &del_table, &dellen))
			return NULL;
	}
	else {
		del_table = NULL;
		dellen = 0;
	}

	inlen = PyString_GET_SIZE(input_obj);
	result = PyString_FromStringAndSize((char *)NULL, inlen);
	if (result == NULL)
		return NULL;
	output_start = output = PyString_AsString(result);
	input = PyString_AS_STRING(input_obj);

	if (dellen == 0 && table != NULL) {
		/* If no deletions are required, use faster code */
		for (i = inlen; --i >= 0; ) {
			c = Py_CHARMASK(*input++);
			if (Py_CHARMASK((*output++ = table[c])) != c)
				changed = 1;
		}
		if (changed || !PyString_CheckExact(input_obj))
			return result;
		Py_DECREF(result);
		Py_INCREF(input_obj);
		return input_obj;
	}

	if (table == NULL) {
		for (i = 0; i < 256; i++)
			trans_table[i] = Py_CHARMASK(i);
	} else {
		for (i = 0; i < 256; i++)
			trans_table[i] = Py_CHARMASK(table[i]);
	}

	for (i = 0; i < dellen; i++)
		trans_table[(int) Py_CHARMASK(del_table[i])] = -1;

	for (i = inlen; --i >= 0; ) {
		c = Py_CHARMASK(*input++);
		if (trans_table[c] != -1)
			if (Py_CHARMASK(*output++ = (char)trans_table[c]) == c)
				continue;
		changed = 1;
	}
	if (!changed && PyString_CheckExact(input_obj)) {
		Py_DECREF(result);
		Py_INCREF(input_obj);
		return input_obj;
	}
	/* Fix the size of the resulting string */
	if (inlen > 0)
		_PyString_Resize(&result, output - output_start);
	return result;
}


#define FORWARD 1
#define REVERSE -1

/* find and count characters and substrings */

#define findchar(target, target_len, c)				\
  ((char *)memchr((const void *)(target), c, target_len))

/* String ops must return a string.  */
/* If the object is subclass of string, create a copy */
Py_LOCAL(PyStringObject *)
return_self(PyStringObject *self)
{
	if (PyString_CheckExact(self)) {
		Py_INCREF(self);
		return self;
	}
	return (PyStringObject *)PyString_FromStringAndSize(
		PyString_AS_STRING(self),
		PyString_GET_SIZE(self));
}

Py_LOCAL_INLINE(Py_ssize_t)
countchar(const char *target, int target_len, char c, Py_ssize_t maxcount)
{
	Py_ssize_t count=0;
	const char *start=target;
	const char *end=target+target_len;

	while ( (start=findchar(start, end-start, c)) != NULL ) {
		count++;
		if (count >= maxcount)
			break;
		start += 1;
	}
	return count;
}

Py_LOCAL(Py_ssize_t)
findstring(const char *target, Py_ssize_t target_len,
	   const char *pattern, Py_ssize_t pattern_len,
	   Py_ssize_t start,
	   Py_ssize_t end,
	   int direction)
{
	if (start < 0) {
		start += target_len;
		if (start < 0)
			start = 0;
	}
	if (end > target_len) {
		end = target_len;
	} else if (end < 0) {
		end += target_len;
		if (end < 0)
			end = 0;
	}

	/* zero-length substrings always match at the first attempt */
	if (pattern_len == 0)
		return (direction > 0) ? start : end;

	end -= pattern_len;

	if (direction < 0) {
		for (; end >= start; end--)
			if (Py_STRING_MATCH(target, end, pattern, pattern_len))
				return end;
	} else {
		for (; start <= end; start++)
			if (Py_STRING_MATCH(target, start, pattern, pattern_len))
				return start;
	}
	return -1;
}

Py_LOCAL_INLINE(Py_ssize_t)
countstring(const char *target, Py_ssize_t target_len,
	    const char *pattern, Py_ssize_t pattern_len,
	    Py_ssize_t start,
	    Py_ssize_t end,
	    int direction, Py_ssize_t maxcount)
{
	Py_ssize_t count=0;

	if (start < 0) {
		start += target_len;
		if (start < 0)
			start = 0;
	}
	if (end > target_len) {
		end = target_len;
	} else if (end < 0) {
		end += target_len;
		if (end < 0)
			end = 0;
	}

	/* zero-length substrings match everywhere */
	if (pattern_len == 0 || maxcount == 0) {
		if (target_len+1 < maxcount)
			return target_len+1;
		return maxcount;
	}

	end -= pattern_len;
	if (direction < 0) {
		for (; (end >= start); end--)
			if (Py_STRING_MATCH(target, end, pattern, pattern_len)) {
				count++;
				if (--maxcount <= 0) break;
				end -= pattern_len-1;
			}
	} else {
		for (; (start <= end); start++)
			if (Py_STRING_MATCH(target, start, pattern, pattern_len)) {
				count++;
				if (--maxcount <= 0)
					break;
				start += pattern_len-1;
			}
	}
	return count;
}


/* Algorithms for different cases of string replacement */

/* len(self)>=1, from="", len(to)>=1, maxcount>=1 */
Py_LOCAL(PyStringObject *)
replace_interleave(PyStringObject *self,
		   const char *to_s, Py_ssize_t to_len,
		   Py_ssize_t maxcount)
{
	char *self_s, *result_s;
	Py_ssize_t self_len, result_len;
	Py_ssize_t count, i, product;
	PyStringObject *result;

	self_len = PyString_GET_SIZE(self);

	/* 1 at the end plus 1 after every character */
	count = self_len+1;
	if (maxcount < count) 
		count = maxcount;

	/* Check for overflow */
	/*   result_len = count * to_len + self_len; */
	product = count * to_len;
	if (product / to_len != count) {
		PyErr_SetString(PyExc_OverflowError,
				"replace string is too long");
		return NULL;
	}
	result_len = product + self_len;
	if (result_len < 0) {
		PyErr_SetString(PyExc_OverflowError,
				"replace string is too long");
		return NULL;
	}
  
	if (! (result = (PyStringObject *)
	                 PyString_FromStringAndSize(NULL, result_len)) )
		return NULL;

	self_s = PyString_AS_STRING(self);
	result_s = PyString_AS_STRING(result);

	/* TODO: special case single character, which doesn't need memcpy */

	/* Lay the first one down (guaranteed this will occur) */
	Py_MEMCPY(result_s, to_s, to_len);
	result_s += to_len;
	count -= 1;
  
	for (i=0; i<count; i++) {
		*result_s++ = *self_s++;
		Py_MEMCPY(result_s, to_s, to_len);
		result_s += to_len;
	}

	/* Copy the rest of the original string */
	Py_MEMCPY(result_s, self_s, self_len-i);

	return result;
}

/* Special case for deleting a single character */
/* len(self)>=1, len(from)==1, to="", maxcount>=1 */
Py_LOCAL(PyStringObject *)
replace_delete_single_character(PyStringObject *self,
				char from_c, Py_ssize_t maxcount)
{
	char *self_s, *result_s;
	char *start, *next, *end;
	Py_ssize_t self_len, result_len;
	Py_ssize_t count;
	PyStringObject *result;

	self_len = PyString_GET_SIZE(self);
	self_s = PyString_AS_STRING(self);

	count = countchar(self_s, self_len, from_c, maxcount);
	if (count == 0) {
		return return_self(self);
	}
  
	result_len = self_len - count;  /* from_len == 1 */
	assert(result_len>=0);

	if ( (result = (PyStringObject *)
	                PyString_FromStringAndSize(NULL, result_len)) == NULL)
		return NULL;
	result_s = PyString_AS_STRING(result);

	start = self_s;
	end = self_s + self_len;
	while (count-- > 0) {
		next = findchar(start, end-start, from_c);
		if (next == NULL)
			break;
		Py_MEMCPY(result_s, start, next-start);
		result_s += (next-start);
		start = next+1;
	}
	Py_MEMCPY(result_s, start, end-start);

	return result;
}

/* len(self)>=1, len(from)>=2, to="", maxcount>=1 */

Py_LOCAL(PyStringObject *)
replace_delete_substring(PyStringObject *self,
			 const char *from_s, Py_ssize_t from_len,
			 Py_ssize_t maxcount) {
	char *self_s, *result_s;
	char *start, *next, *end;
	Py_ssize_t self_len, result_len;
	Py_ssize_t count, offset;
	PyStringObject *result;

	self_len = PyString_GET_SIZE(self);
	self_s = PyString_AS_STRING(self);

	count = countstring(self_s, self_len,
			    from_s, from_len,
			    0, self_len, 1,
			    maxcount);

	if (count == 0) {
		/* no matches */
		return return_self(self);
	}

	result_len = self_len - (count * from_len);
	assert (result_len>=0);

	if ( (result = (PyStringObject *)
	      PyString_FromStringAndSize(NULL, result_len)) == NULL )
		return NULL;

	result_s = PyString_AS_STRING(result);

	start = self_s;
	end = self_s + self_len;
	while (count-- > 0) {
		offset = findstring(start, end-start,
				    from_s, from_len,
				    0, end-start, FORWARD);
		if (offset == -1)
			break;
		next = start + offset;

		Py_MEMCPY(result_s, start, next-start);

		result_s += (next-start);
		start = next+from_len;
	}
	Py_MEMCPY(result_s, start, end-start);
	return result;
}

/* len(self)>=1, len(from)==len(to)==1, maxcount>=1 */
Py_LOCAL(PyStringObject *)
replace_single_character_in_place(PyStringObject *self,
				  char from_c, char to_c,
				  Py_ssize_t maxcount)
{
	char *self_s, *result_s, *start, *end, *next;
	Py_ssize_t self_len;
	PyStringObject *result;

	/* The result string will be the same size */
	self_s = PyString_AS_STRING(self);
	self_len = PyString_GET_SIZE(self);

	next = findchar(self_s, self_len, from_c);

	if (next == NULL) {
		/* No matches; return the original string */
		return return_self(self);
	}

	/* Need to make a new string */
	result = (PyStringObject *) PyString_FromStringAndSize(NULL, self_len);
	if (result == NULL)
		return NULL;
	result_s = PyString_AS_STRING(result);
	Py_MEMCPY(result_s, self_s, self_len);

	/* change everything in-place, starting with this one */
	start =  result_s + (next-self_s);
	*start = to_c;
	start++;
	end = result_s + self_len;

	while (--maxcount > 0) {
		next = findchar(start, end-start, from_c);
		if (next == NULL)
			break;
		*next = to_c;
		start = next+1;
	}

	return result;
}

/* len(self)>=1, len(from)==len(to)>=2, maxcount>=1 */
Py_LOCAL(PyStringObject *)
replace_substring_in_place(PyStringObject *self,
			   const char *from_s, Py_ssize_t from_len,
			   const char *to_s, Py_ssize_t to_len,
			   Py_ssize_t maxcount)
{
	char *result_s, *start, *end;
	char *self_s;
	Py_ssize_t self_len, offset;
	PyStringObject *result;

	/* The result string will be the same size */

	self_s = PyString_AS_STRING(self);
	self_len = PyString_GET_SIZE(self);

	offset = findstring(self_s, self_len,
			    from_s, from_len,
			    0, self_len, FORWARD);
	if (offset == -1) {
		/* No matches; return the original string */
		return return_self(self);
	}

	/* Need to make a new string */
	result = (PyStringObject *) PyString_FromStringAndSize(NULL, self_len);
	if (result == NULL)
		return NULL;
	result_s = PyString_AS_STRING(result);
	Py_MEMCPY(result_s, self_s, self_len);

	/* change everything in-place, starting with this one */
	start =  result_s + offset;
	Py_MEMCPY(start, to_s, from_len);
	start += from_len;
	end = result_s + self_len;

	while ( --maxcount > 0) {
		offset = findstring(start, end-start,
				    from_s, from_len,
				    0, end-start, FORWARD);
		if (offset==-1)
			break;
		Py_MEMCPY(start+offset, to_s, from_len);
		start += offset+from_len;
	}

	return result;
}

/* len(self)>=1, len(from)==1, len(to)>=2, maxcount>=1 */
Py_LOCAL(PyStringObject *)
replace_single_character(PyStringObject *self,
			 char from_c,
			 const char *to_s, Py_ssize_t to_len,
			 Py_ssize_t maxcount)
{
	char *self_s, *result_s;
	char *start, *next, *end;
	Py_ssize_t self_len, result_len;
	Py_ssize_t count, product;
	PyStringObject *result;

	self_s = PyString_AS_STRING(self);
	self_len = PyString_GET_SIZE(self);

	count = countchar(self_s, self_len, from_c, maxcount);
	if (count == 0) {
		/* no matches, return unchanged */
		return return_self(self);
	}

	/* use the difference between current and new, hence the "-1" */
	/*   result_len = self_len + count * (to_len-1)  */
	product = count * (to_len-1);
	if (product / (to_len-1) != count) {
		PyErr_SetString(PyExc_OverflowError, "replace string is too long");
		return NULL;
	}
	result_len = self_len + product;
	if (result_len < 0) {
		PyErr_SetString(PyExc_OverflowError, "replace string is too long");
		return NULL;
	}

	if ( (result = (PyStringObject *)
	      PyString_FromStringAndSize(NULL, result_len)) == NULL)
		return NULL;
	result_s = PyString_AS_STRING(result);

	start = self_s;
	end = self_s + self_len;
	while (count-- > 0) {
		next = findchar(start, end-start, from_c);
		if (next == NULL) 
			break;

		if (next == start) {
			/* replace with the 'to' */
			Py_MEMCPY(result_s, to_s, to_len);
			result_s += to_len;
			start += 1;
		} else {
			/* copy the unchanged old then the 'to' */
			Py_MEMCPY(result_s, start, next-start);
			result_s += (next-start);
			Py_MEMCPY(result_s, to_s, to_len);
			result_s += to_len;
			start = next+1;
		}
	}
	/* Copy the remainder of the remaining string */
	Py_MEMCPY(result_s, start, end-start);

	return result;
}

/* len(self)>=1, len(from)>=2, len(to)>=2, maxcount>=1 */
Py_LOCAL(PyStringObject *)
replace_substring(PyStringObject *self,
		  const char *from_s, Py_ssize_t from_len,
		  const char *to_s, Py_ssize_t to_len,
		  Py_ssize_t maxcount) {
	char *self_s, *result_s;
	char *start, *next, *end;
	Py_ssize_t self_len, result_len;
	Py_ssize_t count, offset, product;
	PyStringObject *result;

	self_s = PyString_AS_STRING(self);
	self_len = PyString_GET_SIZE(self);

	count = countstring(self_s, self_len,
			    from_s, from_len,
			    0, self_len, FORWARD, maxcount);
	if (count == 0) {
		/* no matches, return unchanged */
		return return_self(self);
	}

	/* Check for overflow */
	/*    result_len = self_len + count * (to_len-from_len) */
	product = count * (to_len-from_len);
	if (product / (to_len-from_len) != count) {
		PyErr_SetString(PyExc_OverflowError, "replace string is too long");
		return NULL;
	}
	result_len = self_len + product;
	if (result_len < 0) {
		PyErr_SetString(PyExc_OverflowError, "replace string is too long");
		return NULL;
	}

	if ( (result = (PyStringObject *)
	      PyString_FromStringAndSize(NULL, result_len)) == NULL)
		return NULL;
	result_s = PyString_AS_STRING(result);

	start = self_s;
	end = self_s + self_len;
	while (count-- > 0) {
		offset = findstring(start, end-start,
				    from_s, from_len,
				    0, end-start, FORWARD);
		if (offset == -1)
			break;
		next = start+offset;
		if (next == start) {
			/* replace with the 'to' */
			Py_MEMCPY(result_s, to_s, to_len);
			result_s += to_len;
			start += from_len;
		} else {
			/* copy the unchanged old then the 'to' */
			Py_MEMCPY(result_s, start, next-start);
			result_s += (next-start);
			Py_MEMCPY(result_s, to_s, to_len);
			result_s += to_len;
			start = next+from_len;
		}
	}
	/* Copy the remainder of the remaining string */
	Py_MEMCPY(result_s, start, end-start);

	return result;
}


Py_LOCAL(PyStringObject *)
replace(PyStringObject *self,
	const char *from_s, Py_ssize_t from_len,
	const char *to_s, Py_ssize_t to_len,
	Py_ssize_t maxcount)
{
	if (maxcount < 0) {
		maxcount = PY_SSIZE_T_MAX;
	} else if (maxcount == 0 || PyString_GET_SIZE(self) == 0) {
		/* nothing to do; return the original string */
		return return_self(self);
	}

	if (maxcount == 0 ||
	    (from_len == 0 && to_len == 0)) {
		/* nothing to do; return the original string */
		return return_self(self);
	}

	/* Handle zero-length special cases */

	if (from_len == 0) {
		/* insert the 'to' string everywhere.   */
		/*    >>> "Python".replace("", ".")     */
		/*    '.P.y.t.h.o.n.'                   */
		return replace_interleave(self, to_s, to_len, maxcount);
	}

	/* Except for "".replace("", "A") == "A" there is no way beyond this */
	/* point for an empty self string to generate a non-empty string */
	/* Special case so the remaining code always gets a non-empty string */
	if (PyString_GET_SIZE(self) == 0) {
		return return_self(self);
	}

	if (to_len == 0) {
		/* delete all occurances of 'from' string */
		if (from_len == 1) {
			return replace_delete_single_character(
				self, from_s[0], maxcount);
		} else {
			return replace_delete_substring(self, from_s, from_len, maxcount);
		}
	}

	/* Handle special case where both strings have the same length */

	if (from_len == to_len) {
		if (from_len == 1) {
			return replace_single_character_in_place(
				self,
				from_s[0],
				to_s[0],
				maxcount);
		} else {
			return replace_substring_in_place(
				self, from_s, from_len, to_s, to_len, maxcount);
		}
	}

	/* Otherwise use the more generic algorithms */
	if (from_len == 1) {
		return replace_single_character(self, from_s[0],
						to_s, to_len, maxcount);
	} else {
		/* len('from')>=2, len('to')>=1 */
		return replace_substring(self, from_s, from_len, to_s, to_len, maxcount);
	}
}

PyDoc_STRVAR(replace__doc__,
"S.replace (old, new[, count]) -> string\n\
\n\
Return a copy of string S with all occurrences of substring\n\
old replaced by new.  If the optional argument count is\n\
given, only the first count occurrences are replaced.");

static PyObject *
string_replace(PyStringObject *self, PyObject *args)
{
	Py_ssize_t count = -1;
	PyObject *from, *to;
	const char *from_s, *to_s;
	Py_ssize_t from_len, to_len;

	if (!PyArg_ParseTuple(args, "OO|n:replace", &from, &to, &count))
		return NULL;

	if (PyString_Check(from)) {
		from_s = PyString_AS_STRING(from);
		from_len = PyString_GET_SIZE(from);
	}
	if (PyUnicode_Check(from))
		return PyUnicode_Replace((PyObject *)self,
					 from, to, count);
	else if (PyObject_AsCharBuffer(from, &from_s, &from_len))
		return NULL;

	if (PyString_Check(to)) {
		to_s = PyString_AS_STRING(to);
		to_len = PyString_GET_SIZE(to);
	}
	else if (PyUnicode_Check(to))
		return PyUnicode_Replace((PyObject *)self,
					 from, to, count);
	else if (PyObject_AsCharBuffer(to, &to_s, &to_len))
		return NULL;

	return (PyObject *)replace((PyStringObject *) self,
				   from_s, from_len,
				   to_s, to_len, count);
}

/** End DALKE **/

/* Matches the end (direction >= 0) or start (direction < 0) of self
 * against substr, using the start and end arguments. Returns
 * -1 on error, 0 if not found and 1 if found.
 */
Py_LOCAL(int)
_string_tailmatch(PyStringObject *self, PyObject *substr, Py_ssize_t start,
		  Py_ssize_t end, int direction)
{
	Py_ssize_t len = PyString_GET_SIZE(self);
	Py_ssize_t slen;
	const char* sub;
	const char* str;

	if (PyString_Check(substr)) {
		sub = PyString_AS_STRING(substr);
		slen = PyString_GET_SIZE(substr);
	}
	else if (PyUnicode_Check(substr))
		return PyUnicode_Tailmatch((PyObject *)self,
					   substr, start, end, direction);
	else if (PyObject_AsCharBuffer(substr, &sub, &slen))
		return -1;
	str = PyString_AS_STRING(self);

	string_adjust_indices(&start, &end, len);

	if (direction < 0) {
		/* startswith */
		if (start+slen > len)
			return 0;
	} else {
		/* endswith */
		if (end-start < slen || start > len)
			return 0;

		if (end-slen > start)
			start = end - slen;
	}
	if (end-start >= slen)
		return ! memcmp(str+start, sub, slen);
	return 0;
}


PyDoc_STRVAR(startswith__doc__,
"S.startswith(prefix[, start[, end]]) -> bool\n\
\n\
Return True if S starts with the specified prefix, False otherwise.\n\
With optional start, test S beginning at that position.\n\
With optional end, stop comparing S at that position.\n\
prefix can also be a tuple of strings to try.");

static PyObject *
string_startswith(PyStringObject *self, PyObject *args)
{
	Py_ssize_t start = 0;
	Py_ssize_t end = PY_SSIZE_T_MAX;
	PyObject *subobj;
	int result;

	if (!PyArg_ParseTuple(args, "O|O&O&:startswith", &subobj,
		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
		return NULL;
	if (PyTuple_Check(subobj)) {
		Py_ssize_t i;
		for (i = 0; i < PyTuple_GET_SIZE(subobj); i++) {
			result = _string_tailmatch(self,
					PyTuple_GET_ITEM(subobj, i),
					start, end, -1);
			if (result == -1)
				return NULL;
			else if (result) {
				Py_RETURN_TRUE;
			}
		}
		Py_RETURN_FALSE;
	}
	result = _string_tailmatch(self, subobj, start, end, -1);
	if (result == -1)
		return NULL;
	else
		return PyBool_FromLong(result);
}


PyDoc_STRVAR(endswith__doc__,
"S.endswith(suffix[, start[, end]]) -> bool\n\
\n\
Return True if S ends with the specified suffix, False otherwise.\n\
With optional start, test S beginning at that position.\n\
With optional end, stop comparing S at that position.\n\
suffix can also be a tuple of strings to try.");

static PyObject *
string_endswith(PyStringObject *self, PyObject *args)
{
	Py_ssize_t start = 0;
	Py_ssize_t end = PY_SSIZE_T_MAX;
	PyObject *subobj;
	int result;

	if (!PyArg_ParseTuple(args, "O|O&O&:endswith", &subobj,
		_PyEval_SliceIndex, &start, _PyEval_SliceIndex, &end))
		return NULL;
	if (PyTuple_Check(subobj)) {
		Py_ssize_t i;
		for (i = 0; i < PyTuple_GET_SIZE(subobj); i++) {
			result = _string_tailmatch(self,
					PyTuple_GET_ITEM(subobj, i),
					start, end, +1);
			if (result == -1)
				return NULL;
			else if (result) {
				Py_RETURN_TRUE;
			}
		}
		Py_RETURN_FALSE;
	}
	result = _string_tailmatch(self, subobj, start, end, +1);
	if (result == -1)
		return NULL;
	else
		return PyBool_FromLong(result);
}


PyDoc_STRVAR(encode__doc__,
"S.encode([encoding[,errors]]) -> object\n\
\n\
Encodes S using the codec registered for encoding. encoding defaults\n\
to the default encoding. errors may be given to set a different error\n\
handling scheme. Default is 'strict' meaning that encoding errors raise\n\
a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and\n\
'xmlcharrefreplace' as well as any other name registered with\n\
codecs.register_error that is able to handle UnicodeEncodeErrors.");

static PyObject *
string_encode(PyStringObject *self, PyObject *args)
{
    char *encoding = NULL;
    char *errors = NULL;
    PyObject *v;

    if (!PyArg_ParseTuple(args, "|ss:encode", &encoding, &errors))
        return NULL;
    v = PyString_AsEncodedObject((PyObject *)self, encoding, errors);
    if (v == NULL)
        goto onError;
    if (!PyBytes_Check(v)) {
        PyErr_Format(PyExc_TypeError,
                     "[str8] encoder did not return a bytes object "
                     "(type=%.400s)",
                     v->ob_type->tp_name);
        Py_DECREF(v);
        return NULL;
    }
    return v;

 onError:
    return NULL;
}


PyDoc_STRVAR(decode__doc__,
"S.decode([encoding[,errors]]) -> object\n\
\n\
Decodes S using the codec registered for encoding. encoding defaults\n\
to the default encoding. errors may be given to set a different error\n\
handling scheme. Default is 'strict' meaning that encoding errors raise\n\
a UnicodeDecodeError. Other possible values are 'ignore' and 'replace'\n\
as well as any other name registerd with codecs.register_error that is\n\
able to handle UnicodeDecodeErrors.");

static PyObject *
string_decode(PyStringObject *self, PyObject *args)
{
    char *encoding = NULL;
    char *errors = NULL;
    PyObject *v;

    if (!PyArg_ParseTuple(args, "|ss:decode", &encoding, &errors))
        return NULL;
    v = PyString_AsDecodedObject((PyObject *)self, encoding, errors);
    if (v == NULL)
        goto onError;
    if (!PyString_Check(v) && !PyUnicode_Check(v)) {
        PyErr_Format(PyExc_TypeError,
                     "decoder did not return a string/unicode object "
                     "(type=%.400s)",
                     v->ob_type->tp_name);
        Py_DECREF(v);
        return NULL;
    }
    return v;

 onError:
    return NULL;
}


PyDoc_STRVAR(expandtabs__doc__,
"S.expandtabs([tabsize]) -> string\n\
\n\
Return a copy of S where all tab characters are expanded using spaces.\n\
If tabsize is not given, a tab size of 8 characters is assumed.");

static PyObject*
string_expandtabs(PyStringObject *self, PyObject *args)
{
    const char *e, *p;
    char *q;
    Py_ssize_t i, j;
    PyObject *u;
    int tabsize = 8;

    if (!PyArg_ParseTuple(args, "|i:expandtabs", &tabsize))
	return NULL;

    /* First pass: determine size of output string */
    i = j = 0;
    e = PyString_AS_STRING(self) + PyString_GET_SIZE(self);
    for (p = PyString_AS_STRING(self); p < e; p++)
        if (*p == '\t') {
	    if (tabsize > 0)
		j += tabsize - (j % tabsize);
	}
        else {
            j++;
            if (*p == '\n' || *p == '\r') {
                i += j;
                j = 0;
            }
        }

    /* Second pass: create output string and fill it */
    u = PyString_FromStringAndSize(NULL, i + j);
    if (!u)
        return NULL;

    j = 0;
    q = PyString_AS_STRING(u);

    for (p = PyString_AS_STRING(self); p < e; p++)
        if (*p == '\t') {
	    if (tabsize > 0) {
		i = tabsize - (j % tabsize);
		j += i;
		while (i--)
		    *q++ = ' ';
	    }
	}
	else {
            j++;
	    *q++ = *p;
            if (*p == '\n' || *p == '\r')
                j = 0;
        }

    return u;
}

Py_LOCAL_INLINE(PyObject *)
pad(PyStringObject *self, Py_ssize_t left, Py_ssize_t right, char fill)
{
    PyObject *u;

    if (left < 0)
        left = 0;
    if (right < 0)
        right = 0;

    if (left == 0 && right == 0 && PyString_CheckExact(self)) {
        Py_INCREF(self);
        return (PyObject *)self;
    }

    u = PyString_FromStringAndSize(NULL,
				   left + PyString_GET_SIZE(self) + right);
    if (u) {
        if (left)
            memset(PyString_AS_STRING(u), fill, left);
        Py_MEMCPY(PyString_AS_STRING(u) + left,
	       PyString_AS_STRING(self),
	       PyString_GET_SIZE(self));
        if (right)
            memset(PyString_AS_STRING(u) + left + PyString_GET_SIZE(self),
		   fill, right);
    }

    return u;
}

PyDoc_STRVAR(ljust__doc__,
"S.ljust(width[, fillchar]) -> string\n"
"\n"
"Return S left justified in a string of length width. Padding is\n"
"done using the specified fill character (default is a space).");

static PyObject *
string_ljust(PyStringObject *self, PyObject *args)
{
    Py_ssize_t width;
    char fillchar = ' ';

    if (!PyArg_ParseTuple(args, "n|c:ljust", &width, &fillchar))
        return NULL;

    if (PyString_GET_SIZE(self) >= width && PyString_CheckExact(self)) {
        Py_INCREF(self);
        return (PyObject*) self;
    }

    return pad(self, 0, width - PyString_GET_SIZE(self), fillchar);
}


PyDoc_STRVAR(rjust__doc__,
"S.rjust(width[, fillchar]) -> string\n"
"\n"
"Return S right justified in a string of length width. Padding is\n"
"done using the specified fill character (default is a space)");

static PyObject *
string_rjust(PyStringObject *self, PyObject *args)
{
    Py_ssize_t width;
    char fillchar = ' ';

    if (!PyArg_ParseTuple(args, "n|c:rjust", &width, &fillchar))
        return NULL;

    if (PyString_GET_SIZE(self) >= width && PyString_CheckExact(self)) {
        Py_INCREF(self);
        return (PyObject*) self;
    }

    return pad(self, width - PyString_GET_SIZE(self), 0, fillchar);
}


PyDoc_STRVAR(center__doc__,
"S.center(width[, fillchar]) -> string\n"
"\n"
"Return S centered in a string of length width. Padding is\n"
"done using the specified fill character (default is a space)");

static PyObject *
string_center(PyStringObject *self, PyObject *args)
{
    Py_ssize_t marg, left;
    Py_ssize_t width;
    char fillchar = ' ';

    if (!PyArg_ParseTuple(args, "n|c:center", &width, &fillchar))
        return NULL;

    if (PyString_GET_SIZE(self) >= width && PyString_CheckExact(self)) {
        Py_INCREF(self);
        return (PyObject*) self;
    }

    marg = width - PyString_GET_SIZE(self);
    left = marg / 2 + (marg & width & 1);

    return pad(self, left, marg - left, fillchar);
}

PyDoc_STRVAR(zfill__doc__,
"S.zfill(width) -> string\n"
"\n"
"Pad a numeric string S with zeros on the left, to fill a field\n"
"of the specified width.  The string S is never truncated.");

static PyObject *
string_zfill(PyStringObject *self, PyObject *args)
{
    Py_ssize_t fill;
    PyObject *s;
    char *p;
    Py_ssize_t width;

    if (!PyArg_ParseTuple(args, "n:zfill", &width))
        return NULL;

    if (PyString_GET_SIZE(self) >= width) {
        if (PyString_CheckExact(self)) {
            Py_INCREF(self);
            return (PyObject*) self;
        }
        else
            return PyString_FromStringAndSize(
                PyString_AS_STRING(self),
                PyString_GET_SIZE(self)
            );
    }

    fill = width - PyString_GET_SIZE(self);

    s = pad(self, fill, 0, '0');

    if (s == NULL)
        return NULL;

    p = PyString_AS_STRING(s);
    if (p[fill] == '+' || p[fill] == '-') {
        /* move sign to beginning of string */
        p[0] = p[fill];
        p[fill] = '0';
    }

    return (PyObject*) s;
}

PyDoc_STRVAR(isspace__doc__,
"S.isspace() -> bool\n\
\n\
Return True if all characters in S are whitespace\n\
and there is at least one character in S, False otherwise.");

static PyObject*
string_isspace(PyStringObject *self)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1 &&
	isspace(*p))
	return PyBool_FromLong(1);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
	return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    for (; p < e; p++) {
	if (!isspace(*p))
	    return PyBool_FromLong(0);
    }
    return PyBool_FromLong(1);
}


PyDoc_STRVAR(isalpha__doc__,
"S.isalpha() -> bool\n\
\n\
Return True if all characters in S are alphabetic\n\
and there is at least one character in S, False otherwise.");

static PyObject*
string_isalpha(PyStringObject *self)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1 &&
	isalpha(*p))
	return PyBool_FromLong(1);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
	return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    for (; p < e; p++) {
	if (!isalpha(*p))
	    return PyBool_FromLong(0);
    }
    return PyBool_FromLong(1);
}


PyDoc_STRVAR(isalnum__doc__,
"S.isalnum() -> bool\n\
\n\
Return True if all characters in S are alphanumeric\n\
and there is at least one character in S, False otherwise.");

static PyObject*
string_isalnum(PyStringObject *self)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1 &&
	isalnum(*p))
	return PyBool_FromLong(1);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
	return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    for (; p < e; p++) {
	if (!isalnum(*p))
	    return PyBool_FromLong(0);
    }
    return PyBool_FromLong(1);
}


PyDoc_STRVAR(isdigit__doc__,
"S.isdigit() -> bool\n\
\n\
Return True if all characters in S are digits\n\
and there is at least one character in S, False otherwise.");

static PyObject*
string_isdigit(PyStringObject *self)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1 &&
	isdigit(*p))
	return PyBool_FromLong(1);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
	return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    for (; p < e; p++) {
	if (!isdigit(*p))
	    return PyBool_FromLong(0);
    }
    return PyBool_FromLong(1);
}


PyDoc_STRVAR(islower__doc__,
"S.islower() -> bool\n\
\n\
Return True if all cased characters in S are lowercase and there is\n\
at least one cased character in S, False otherwise.");

static PyObject*
string_islower(PyStringObject *self)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;
    int cased;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1)
	return PyBool_FromLong(islower(*p) != 0);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
	return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    cased = 0;
    for (; p < e; p++) {
	if (isupper(*p))
	    return PyBool_FromLong(0);
	else if (!cased && islower(*p))
	    cased = 1;
    }
    return PyBool_FromLong(cased);
}


PyDoc_STRVAR(isupper__doc__,
"S.isupper() -> bool\n\
\n\
Return True if all cased characters in S are uppercase and there is\n\
at least one cased character in S, False otherwise.");

static PyObject*
string_isupper(PyStringObject *self)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;
    int cased;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1)
	return PyBool_FromLong(isupper(*p) != 0);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
	return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    cased = 0;
    for (; p < e; p++) {
	if (islower(*p))
	    return PyBool_FromLong(0);
	else if (!cased && isupper(*p))
	    cased = 1;
    }
    return PyBool_FromLong(cased);
}


PyDoc_STRVAR(istitle__doc__,
"S.istitle() -> bool\n\
\n\
Return True if S is a titlecased string and there is at least one\n\
character in S, i.e. uppercase characters may only follow uncased\n\
characters and lowercase characters only cased ones. Return False\n\
otherwise.");

static PyObject*
string_istitle(PyStringObject *self, PyObject *uncased)
{
    register const unsigned char *p
        = (unsigned char *) PyString_AS_STRING(self);
    register const unsigned char *e;
    int cased, previous_is_cased;

    /* Shortcut for single character strings */
    if (PyString_GET_SIZE(self) == 1)
	return PyBool_FromLong(isupper(*p) != 0);

    /* Special case for empty strings */
    if (PyString_GET_SIZE(self) == 0)
	return PyBool_FromLong(0);

    e = p + PyString_GET_SIZE(self);
    cased = 0;
    previous_is_cased = 0;
    for (; p < e; p++) {
	register const unsigned char ch = *p;

	if (isupper(ch)) {
	    if (previous_is_cased)
		return PyBool_FromLong(0);
	    previous_is_cased = 1;
	    cased = 1;
	}
	else if (islower(ch)) {
	    if (!previous_is_cased)
		return PyBool_FromLong(0);
	    previous_is_cased = 1;
	    cased = 1;
	}
	else
	    previous_is_cased = 0;
    }
    return PyBool_FromLong(cased);
}


PyDoc_STRVAR(splitlines__doc__,
"S.splitlines([keepends]) -> list of strings\n\
\n\
Return a list of the lines in S, breaking at line boundaries.\n\
Line breaks are not included in the resulting list unless keepends\n\
is given and true.");

static PyObject*
string_splitlines(PyStringObject *self, PyObject *args)
{
    register Py_ssize_t i;
    register Py_ssize_t j;
    Py_ssize_t len;
    int keepends = 0;
    PyObject *list;
    PyObject *str;
    char *data;

    if (!PyArg_ParseTuple(args, "|i:splitlines", &keepends))
        return NULL;

    data = PyString_AS_STRING(self);
    len = PyString_GET_SIZE(self);

    /* This does not use the preallocated list because splitlines is
       usually run with hundreds of newlines.  The overhead of
       switching between PyList_SET_ITEM and append causes about a
       2-3% slowdown for that common case.  A smarter implementation
       could move the if check out, so the SET_ITEMs are done first
       and the appends only done when the prealloc buffer is full.
       That's too much work for little gain.*/

    list = PyList_New(0);
    if (!list)
        goto onError;

    for (i = j = 0; i < len; ) {
	Py_ssize_t eol;

	/* Find a line and append it */
	while (i < len && data[i] != '\n' && data[i] != '\r')
	    i++;

	/* Skip the line break reading CRLF as one line break */
	eol = i;
	if (i < len) {
	    if (data[i] == '\r' && i + 1 < len &&
		data[i+1] == '\n')
		i += 2;
	    else
		i++;
	    if (keepends)
		eol = i;
	}
	SPLIT_APPEND(data, j, eol);
	j = i;
    }
    if (j < len) {
	SPLIT_APPEND(data, j, len);
    }

    return list;

 onError:
    Py_XDECREF(list);
    return NULL;
}

#undef SPLIT_APPEND
#undef SPLIT_ADD
#undef MAX_PREALLOC
#undef PREALLOC_SIZE

static PyObject *
string_getnewargs(PyStringObject *v)
{
	return Py_BuildValue("(s#)", v->ob_sval, v->ob_size);
}


static PyMethodDef
string_methods[] = {
	{"join", (PyCFunction)string_join, METH_O, join__doc__},
	{"split", (PyCFunction)string_split, METH_VARARGS, split__doc__},
	{"rsplit", (PyCFunction)string_rsplit, METH_VARARGS, rsplit__doc__},
	{"lower", (PyCFunction)string_lower, METH_NOARGS, lower__doc__},
	{"upper", (PyCFunction)string_upper, METH_NOARGS, upper__doc__},
	{"islower", (PyCFunction)string_islower, METH_NOARGS, islower__doc__},
	{"isupper", (PyCFunction)string_isupper, METH_NOARGS, isupper__doc__},
	{"isspace", (PyCFunction)string_isspace, METH_NOARGS, isspace__doc__},
	{"isdigit", (PyCFunction)string_isdigit, METH_NOARGS, isdigit__doc__},
	{"istitle", (PyCFunction)string_istitle, METH_NOARGS, istitle__doc__},
	{"isalpha", (PyCFunction)string_isalpha, METH_NOARGS, isalpha__doc__},
	{"isalnum", (PyCFunction)string_isalnum, METH_NOARGS, isalnum__doc__},
	{"capitalize", (PyCFunction)string_capitalize, METH_NOARGS,
	 capitalize__doc__},
	{"count", (PyCFunction)string_count, METH_VARARGS, count__doc__},
	{"endswith", (PyCFunction)string_endswith, METH_VARARGS,
	 endswith__doc__},
	{"partition", (PyCFunction)string_partition, METH_O, partition__doc__},
	{"find", (PyCFunction)string_find, METH_VARARGS, find__doc__},
	{"index", (PyCFunction)string_index, METH_VARARGS, index__doc__},
	{"lstrip", (PyCFunction)string_lstrip, METH_VARARGS, lstrip__doc__},
	{"replace", (PyCFunction)string_replace, METH_VARARGS, replace__doc__},
	{"rfind", (PyCFunction)string_rfind, METH_VARARGS, rfind__doc__},
	{"rindex", (PyCFunction)string_rindex, METH_VARARGS, rindex__doc__},
	{"rstrip", (PyCFunction)string_rstrip, METH_VARARGS, rstrip__doc__},
	{"rpartition", (PyCFunction)string_rpartition, METH_O,
	 rpartition__doc__},
	{"startswith", (PyCFunction)string_startswith, METH_VARARGS,
	 startswith__doc__},
	{"strip", (PyCFunction)string_strip, METH_VARARGS, strip__doc__},
	{"swapcase", (PyCFunction)string_swapcase, METH_NOARGS,
	 swapcase__doc__},
	{"translate", (PyCFunction)string_translate, METH_VARARGS,
	 translate__doc__},
	{"title", (PyCFunction)string_title, METH_NOARGS, title__doc__},
	{"ljust", (PyCFunction)string_ljust, METH_VARARGS, ljust__doc__},
	{"rjust", (PyCFunction)string_rjust, METH_VARARGS, rjust__doc__},
	{"center", (PyCFunction)string_center, METH_VARARGS, center__doc__},
	{"zfill", (PyCFunction)string_zfill, METH_VARARGS, zfill__doc__},
	{"encode", (PyCFunction)string_encode, METH_VARARGS, encode__doc__},
	{"decode", (PyCFunction)string_decode, METH_VARARGS, decode__doc__},
	{"expandtabs", (PyCFunction)string_expandtabs, METH_VARARGS,
	 expandtabs__doc__},
	{"splitlines", (PyCFunction)string_splitlines, METH_VARARGS,
	 splitlines__doc__},
	{"__getnewargs__",	(PyCFunction)string_getnewargs,	METH_NOARGS},
	{NULL,     NULL}		     /* sentinel */
};

static PyObject *
str_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds);

static PyObject *
string_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	PyObject *x = NULL;
	static char *kwlist[] = {"object", 0};

	if (type != &PyString_Type)
		return str_subtype_new(type, args, kwds);
	if (!PyArg_ParseTupleAndKeywords(args, kwds, "|O:str8", kwlist, &x))
		return NULL;
	if (x == NULL)
		return PyString_FromString("");
	return PyObject_Str(x);
}

static PyObject *
str_subtype_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	PyObject *tmp, *pnew;
	Py_ssize_t n;

	assert(PyType_IsSubtype(type, &PyString_Type));
	tmp = string_new(&PyString_Type, args, kwds);
	if (tmp == NULL)
		return NULL;
	assert(PyString_CheckExact(tmp));
	n = PyString_GET_SIZE(tmp);
	pnew = type->tp_alloc(type, n);
	if (pnew != NULL) {
		Py_MEMCPY(PyString_AS_STRING(pnew), PyString_AS_STRING(tmp), n+1);
		((PyStringObject *)pnew)->ob_shash =
			((PyStringObject *)tmp)->ob_shash;
		((PyStringObject *)pnew)->ob_sstate = SSTATE_NOT_INTERNED;
	}
	Py_DECREF(tmp);
	return pnew;
}

static PyObject *
basestring_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
{
	PyErr_SetString(PyExc_TypeError,
			"The basestring type cannot be instantiated");
	return NULL;
}

static PyObject *
string_mod(PyObject *v, PyObject *w)
{
	if (!PyString_Check(v)) {
		Py_INCREF(Py_NotImplemented);
		return Py_NotImplemented;
	}
	return PyString_Format(v, w);
}

PyDoc_STRVAR(basestring_doc,
"Type basestring cannot be instantiated; it is the base for str8 and str.");

static PyNumberMethods string_as_number = {
	0,			/*nb_add*/
	0,			/*nb_subtract*/
	0,			/*nb_multiply*/
	string_mod,		/*nb_remainder*/
};


PyTypeObject PyBaseString_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"basestring",
	0,
	0,
 	0,			 		/* 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 */
	0,					/* tp_getattro */
	0,					/* tp_setattro */
	0,					/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /* tp_flags */
	basestring_doc,				/* tp_doc */
	0,					/* tp_traverse */
	0,					/* tp_clear */
	0,					/* tp_richcompare */
	0,					/* tp_weaklistoffset */
	0,					/* tp_iter */
	0,					/* tp_iternext */
	0,					/* tp_methods */
	0,					/* tp_members */
	0,					/* tp_getset */
	&PyBaseObject_Type,			/* tp_base */
	0,					/* tp_dict */
	0,					/* tp_descr_get */
	0,					/* tp_descr_set */
	0,					/* tp_dictoffset */
	0,					/* tp_init */
	0,					/* tp_alloc */
	basestring_new,				/* tp_new */
	0,		                	/* tp_free */
};

PyDoc_STRVAR(string_doc,
"str(object) -> string\n\
\n\
Return a nice string representation of the object.\n\
If the argument is a string, the return value is the same object.");

static PyObject *str_iter(PyObject *seq);

PyTypeObject PyString_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,
	"str8",
	sizeof(PyStringObject),
	sizeof(char),
 	string_dealloc, 			/* tp_dealloc */
	(printfunc)string_print, 		/* tp_print */
	0,					/* tp_getattr */
	0,					/* tp_setattr */
	0,					/* tp_compare */
	string_repr, 				/* tp_repr */
	&string_as_number,			/* tp_as_number */
	&string_as_sequence,			/* tp_as_sequence */
	&string_as_mapping,			/* tp_as_mapping */
	(hashfunc)string_hash, 			/* tp_hash */
	0,					/* tp_call */
	string_str,				/* tp_str */
	PyObject_GenericGetAttr,		/* tp_getattro */
	0,					/* tp_setattro */
	&string_as_buffer,			/* tp_as_buffer */
	Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE |
		Py_TPFLAGS_STRING_SUBCLASS,	/* tp_flags */
	string_doc,				/* tp_doc */
	0,					/* tp_traverse */
	0,					/* tp_clear */
	(richcmpfunc)string_richcompare,	/* tp_richcompare */
	0,					/* tp_weaklistoffset */
	str_iter,				/* tp_iter */
	0,					/* tp_iternext */
	string_methods,				/* tp_methods */
	0,					/* tp_members */
	0,					/* tp_getset */
	&PyBaseString_Type,			/* tp_base */
	0,					/* tp_dict */
	0,					/* tp_descr_get */
	0,					/* tp_descr_set */
	0,					/* tp_dictoffset */
	0,					/* tp_init */
	0,					/* tp_alloc */
	string_new,				/* tp_new */
	PyObject_Del,	                	/* tp_free */
};

void
PyString_Concat(register PyObject **pv, register PyObject *w)
{
	register PyObject *v;
	if (*pv == NULL)
		return;
	if (w == NULL || !PyString_Check(*pv)) {
		Py_DECREF(*pv);
		*pv = NULL;
		return;
	}
	v = string_concat((PyStringObject *) *pv, w);
	Py_DECREF(*pv);
	*pv = v;
}

void
PyString_ConcatAndDel(register PyObject **pv, register PyObject *w)
{
	PyString_Concat(pv, w);
	Py_XDECREF(w);
}


/* The following function breaks the notion that strings are immutable:
   it changes the size of a string.  We get away with this only if there
   is only one module referencing the object.  You can also think of it
   as creating a new string object and destroying the old one, only
   more efficiently.  In any case, don't use this if the string may
   already be known to some other part of the code...
   Note that if there's not enough memory to resize the string, the original
   string object at *pv is deallocated, *pv is set to NULL, an "out of
   memory" exception is set, and -1 is returned.  Else (on success) 0 is
   returned, and the value in *pv may or may not be the same as on input.
   As always, an extra byte is allocated for a trailing \0 byte (newsize
   does *not* include that), and a trailing \0 byte is stored.
*/

int
_PyString_Resize(PyObject **pv, Py_ssize_t newsize)
{
	register PyObject *v;
	register PyStringObject *sv;
	v = *pv;
	if (!PyString_Check(v) || v->ob_refcnt != 1 || newsize < 0 ||
	    PyString_CHECK_INTERNED(v)) {
		*pv = 0;
		Py_DECREF(v);
		PyErr_BadInternalCall();
		return -1;
	}
	/* XXX UNREF/NEWREF interface should be more symmetrical */
	_Py_DEC_REFTOTAL;
	_Py_ForgetReference(v);
	*pv = (PyObject *)
		PyObject_REALLOC((char *)v, sizeof(PyStringObject) + newsize);
	if (*pv == NULL) {
		PyObject_Del(v);
		PyErr_NoMemory();
		return -1;
	}
	_Py_NewReference(*pv);
	sv = (PyStringObject *) *pv;
	sv->ob_size = newsize;
	sv->ob_sval[newsize] = '\0';
	sv->ob_shash = -1;	/* invalidate cached hash value */
	return 0;
}

/* Helpers for formatstring */

Py_LOCAL_INLINE(PyObject *)
getnextarg(PyObject *args, Py_ssize_t arglen, Py_ssize_t *p_argidx)
{
	Py_ssize_t argidx = *p_argidx;
	if (argidx < arglen) {
		(*p_argidx)++;
		if (arglen < 0)
			return args;
		else
			return PyTuple_GetItem(args, argidx);
	}
	PyErr_SetString(PyExc_TypeError,
			"not enough arguments for format string");
	return NULL;
}

/* Format codes
 * F_LJUST	'-'
 * F_SIGN	'+'
 * F_BLANK	' '
 * F_ALT	'#'
 * F_ZERO	'0'
 */
#define F_LJUST (1<<0)
#define F_SIGN	(1<<1)
#define F_BLANK (1<<2)
#define F_ALT	(1<<3)
#define F_ZERO	(1<<4)

Py_LOCAL_INLINE(int)
formatfloat(char *buf, size_t buflen, int flags,
            int prec, int type, PyObject *v)
{
	/* fmt = '%#.' + `prec` + `type`
	   worst case length = 3 + 10 (len of INT_MAX) + 1 = 14 (use 20)*/
	char fmt[20];
	double x;
	x = PyFloat_AsDouble(v);
	if (x == -1.0 && PyErr_Occurred()) {
		PyErr_Format(PyExc_TypeError, "float argument required, "
			     "not %.200s", v->ob_type->tp_name);
		return -1;
	}
	if (prec < 0)
		prec = 6;
	if (type == 'f' && fabs(x)/1e25 >= 1e25)
		type = 'g';
	/* Worst case length calc to ensure no buffer overrun:

	   'g' formats:
	     fmt = %#.<prec>g
	     buf = '-' + [0-9]*prec + '.' + 'e+' + (longest exp
	        for any double rep.)
	     len = 1 + prec + 1 + 2 + 5 = 9 + prec

	   'f' formats:
	     buf = '-' + [0-9]*x + '.' + [0-9]*prec (with x < 50)
	     len = 1 + 50 + 1 + prec = 52 + prec

	   If prec=0 the effective precision is 1 (the leading digit is
	   always given), therefore increase the length by one.

	*/
	if ((type == 'g' && buflen <= (size_t)10 + (size_t)prec) ||
	    (type == 'f' && buflen <= (size_t)53 + (size_t)prec)) {
		PyErr_SetString(PyExc_OverflowError,
			"formatted float is too long (precision too large?)");
		return -1;
	}
	PyOS_snprintf(fmt, sizeof(fmt), "%%%s.%d%c",
		      (flags&F_ALT) ? "#" : "",
		      prec, type);
        PyOS_ascii_formatd(buf, buflen, fmt, x);
	return (int)strlen(buf);
}

/* _PyString_FormatLong emulates the format codes d, u, o, x and X, and
 * the F_ALT flag, for Python's long (unbounded) ints.  It's not used for
 * Python's regular ints.
 * Return value:  a new PyString*, or NULL if error.
 *  .  *pbuf is set to point into it,
 *     *plen set to the # of chars following that.
 *     Caller must decref it when done using pbuf.
 *     The string starting at *pbuf is of the form
 *         "-"? ("0x" | "0X")? digit+
 *     "0x"/"0X" are present only for x and X conversions, with F_ALT
 *         set in flags.  The case of hex digits will be correct,
 *     There will be at least prec digits, zero-filled on the left if
 *         necessary to get that many.
 * val		object to be converted
 * flags	bitmask of format flags; only F_ALT is looked at
 * prec		minimum number of digits; 0-fill on left if needed
 * type		a character in [duoxX]; u acts the same as d
 *
 * CAUTION:  o, x and X conversions on regular ints can never
 * produce a '-' sign, but can for Python's unbounded ints.
 */
PyObject*
_PyString_FormatLong(PyObject *val, int flags, int prec, int type,
		     char **pbuf, int *plen)
{
	PyObject *result = NULL;
	char *buf;
	Py_ssize_t i;
	int sign;	/* 1 if '-', else 0 */
	int len;	/* number of characters */
	Py_ssize_t llen;
	int numdigits;	/* len == numnondigits + numdigits */
	int numnondigits = 0;

	/* Avoid exceeding SSIZE_T_MAX */
	if (prec > PY_SSIZE_T_MAX-3) {
		PyErr_SetString(PyExc_OverflowError,
				"precision too large");
		return NULL;
	}


	switch (type) {
	case 'd':
	case 'u':
		result = val->ob_type->tp_str(val);
		break;
	case 'o':
		result = val->ob_type->tp_as_number->nb_oct(val);
		break;
	case 'x':
	case 'X':
		numnondigits = 2;
		result = val->ob_type->tp_as_number->nb_hex(val);
		break;
	default:
		assert(!"'type' not in [duoxX]");
	}
	if (!result)
		return NULL;

	buf = PyString_AsString(result);
	if (!buf) {
		Py_DECREF(result);
		return NULL;
	}

	/* To modify the string in-place, there can only be one reference. */
	if (result->ob_refcnt != 1) {
		PyErr_BadInternalCall();
		return NULL;
	}
	llen = PyString_Size(result);
	if (llen > INT_MAX) {
		PyErr_SetString(PyExc_ValueError, "string too large in _PyString_FormatLong");
		return NULL;
	}
	len = (int)llen;
	if (buf[len-1] == 'L') {
		--len;
		buf[len] = '\0';
	}
	sign = buf[0] == '-';
	numnondigits += sign;
	numdigits = len - numnondigits;
	assert(numdigits > 0);

	/* Get rid of base marker unless F_ALT */
	if ((flags & F_ALT) == 0) {
		/* Need to skip 0x, 0X or 0. */
		int skipped = 0;
		switch (type) {
		case 'o':
			assert(buf[sign] == '0');
			/* If 0 is only digit, leave it alone. */
			if (numdigits > 1) {
				skipped = 1;
				--numdigits;
			}
			break;
		case 'x':
		case 'X':
			assert(buf[sign] == '0');
			assert(buf[sign + 1] == 'x');
			skipped = 2;
			numnondigits -= 2;
			break;
		}
		if (skipped) {
			buf += skipped;
			len -= skipped;
			if (sign)
				buf[0] = '-';
		}
		assert(len == numnondigits + numdigits);
		assert(numdigits > 0);
	}

	/* Fill with leading zeroes to meet minimum width. */
	if (prec > numdigits) {
		PyObject *r1 = PyString_FromStringAndSize(NULL,
					numnondigits + prec);
		char *b1;
		if (!r1) {
			Py_DECREF(result);
			return NULL;
		}
		b1 = PyString_AS_STRING(r1);
		for (i = 0; i < numnondigits; ++i)
			*b1++ = *buf++;
		for (i = 0; i < prec - numdigits; i++)
			*b1++ = '0';
		for (i = 0; i < numdigits; i++)
			*b1++ = *buf++;
		*b1 = '\0';
		Py_DECREF(result);
		result = r1;
		buf = PyString_AS_STRING(result);
		len = numnondigits + prec;
	}

	/* Fix up case for hex conversions. */
	if (type == 'X') {
		/* Need to convert all lower case letters to upper case.
		   and need to convert 0x to 0X (and -0x to -0X). */
		for (i = 0; i < len; i++)
			if (buf[i] >= 'a' && buf[i] <= 'x')
				buf[i] -= 'a'-'A';
	}
	*pbuf = buf;
	*plen = len;
	return result;
}

Py_LOCAL_INLINE(int)
formatint(char *buf, size_t buflen, int flags,
          int prec, int type, PyObject *v)
{
	/* fmt = '%#.' + `prec` + 'l' + `type`
	   worst case length = 3 + 19 (worst len of INT_MAX on 64-bit machine)
	   + 1 + 1 = 24 */
	char fmt[64];	/* plenty big enough! */
	char *sign;
	long x;

	x = PyInt_AsLong(v);
	if (x == -1 && PyErr_Occurred()) {
		PyErr_Format(PyExc_TypeError, "int argument required, not %.200s",
			     v->ob_type->tp_name);
		return -1;
	}
	if (x < 0 && type == 'u') {
		type = 'd';
	}
	if (x < 0 && (type == 'x' || type == 'X' || type == 'o'))
		sign = "-";
	else
		sign = "";
	if (prec < 0)
		prec = 1;

	if ((flags & F_ALT) &&
	    (type == 'x' || type == 'X')) {
		/* When converting under %#x or %#X, there are a number
		 * of issues that cause pain:
		 * - when 0 is being converted, the C standard leaves off
		 *   the '0x' or '0X', which is inconsistent with other
		 *   %#x/%#X conversions and inconsistent with Python's
		 *   hex() function
		 * - there are platforms that violate the standard and
		 *   convert 0 with the '0x' or '0X'
		 *   (Metrowerks, Compaq Tru64)
		 * - there are platforms that give '0x' when converting
		 *   under %#X, but convert 0 in accordance with the
		 *   standard (OS/2 EMX)
		 *
		 * We can achieve the desired consistency by inserting our
		 * own '0x' or '0X' prefix, and substituting %x/%X in place
		 * of %#x/%#X.
		 *
		 * Note that this is the same approach as used in
		 * formatint() in unicodeobject.c
		 */
		PyOS_snprintf(fmt, sizeof(fmt), "%s0%c%%.%dl%c",
			      sign, type, prec, type);
	}
	else {
		PyOS_snprintf(fmt, sizeof(fmt), "%s%%%s.%dl%c",
			      sign, (flags&F_ALT) ? "#" : "",
			      prec, type);
	}

	/* buf = '+'/'-'/'' + '0'/'0x'/'' + '[0-9]'*max(prec, len(x in octal))
	 * worst case buf = '-0x' + [0-9]*prec, where prec >= 11
	 */
	if (buflen <= 14 || buflen <= (size_t)3 + (size_t)prec) {
		PyErr_SetString(PyExc_OverflowError,
		    "formatted integer is too long (precision too large?)");
		return -1;
	}
	if (sign[0])
		PyOS_snprintf(buf, buflen, fmt, -x);
	else
		PyOS_snprintf(buf, buflen, fmt, x);
	return (int)strlen(buf);
}

Py_LOCAL_INLINE(int)
formatchar(char *buf, size_t buflen, PyObject *v)
{
	/* presume that the buffer is at least 2 characters long */
	if (PyString_Check(v)) {
		if (!PyArg_Parse(v, "c;%c requires int or char", &buf[0]))
			return -1;
	}
	else {
		if (!PyArg_Parse(v, "b;%c requires int or char", &buf[0]))
			return -1;
	}
	buf[1] = '\0';
	return 1;
}

/* fmt%(v1,v2,...) is roughly equivalent to sprintf(fmt, v1, v2, ...)

   FORMATBUFLEN is the length of the buffer in which the floats, ints, &
   chars are formatted. XXX This is a magic number. Each formatting
   routine does bounds checking to ensure no overflow, but a better
   solution may be to malloc a buffer of appropriate size for each
   format. For now, the current solution is sufficient.
*/
#define FORMATBUFLEN (size_t)120

PyObject *
PyString_Format(PyObject *format, PyObject *args)
{
	char *fmt, *res;
	Py_ssize_t arglen, argidx;
	Py_ssize_t reslen, rescnt, fmtcnt;
	int args_owned = 0;
	PyObject *result, *orig_args;
	PyObject *v, *w;
	PyObject *dict = NULL;
	if (format == NULL || !PyString_Check(format) || args == NULL) {
		PyErr_BadInternalCall();
		return NULL;
	}
	orig_args = args;
	fmt = PyString_AS_STRING(format);
	fmtcnt = PyString_GET_SIZE(format);
	reslen = rescnt = fmtcnt + 100;
	result = PyString_FromStringAndSize((char *)NULL, reslen);
	if (result == NULL)
		return NULL;
	res = PyString_AsString(result);
	if (PyTuple_Check(args)) {
		arglen = PyTuple_GET_SIZE(args);
		argidx = 0;
	}
	else {
		arglen = -1;
		argidx = -2;
	}
	if (args->ob_type->tp_as_mapping && !PyTuple_Check(args) &&
	    !PyObject_TypeCheck(args, &PyBaseString_Type))
		dict = args;
	while (--fmtcnt >= 0) {
		if (*fmt != '%') {
			if (--rescnt < 0) {
				rescnt = fmtcnt + 100;
				reslen += rescnt;
				if (_PyString_Resize(&result, reslen) < 0)
					return NULL;
				res = PyString_AS_STRING(result)
					+ reslen - rescnt;
				--rescnt;
			}
			*res++ = *fmt++;
		}
		else {
			/* Got a format specifier */
			int flags = 0;
			Py_ssize_t width = -1;
			int prec = -1;
			int c = '\0';
			int fill;
			PyObject *v = NULL;
			PyObject *temp = NULL;
			char *pbuf;
			int sign;
			Py_ssize_t len;
			char formatbuf[FORMATBUFLEN];
			     /* For format{float,int,char}() */
			char *fmt_start = fmt;
			Py_ssize_t argidx_start = argidx;

			fmt++;
			if (*fmt == '(') {
				char *keystart;
				Py_ssize_t keylen;
				PyObject *key;
				int pcount = 1;

				if (dict == NULL) {
					PyErr_SetString(PyExc_TypeError,
						 "format requires a mapping");
					goto error;
				}
				++fmt;
				--fmtcnt;
				keystart = fmt;
				/* Skip over balanced parentheses */
				while (pcount > 0 && --fmtcnt >= 0) {
					if (*fmt == ')')
						--pcount;
					else if (*fmt == '(')
						++pcount;
					fmt++;
				}
				keylen = fmt - keystart - 1;
				if (fmtcnt < 0 || pcount > 0) {
					PyErr_SetString(PyExc_ValueError,
						   "incomplete format key");
					goto error;
				}
				key = PyString_FromStringAndSize(keystart,
								 keylen);
				if (key == NULL)
					goto error;
				if (args_owned) {
					Py_DECREF(args);
					args_owned = 0;
				}
				args = PyObject_GetItem(dict, key);
				Py_DECREF(key);
				if (args == NULL) {
					goto error;
				}
				args_owned = 1;
				arglen = -1;
				argidx = -2;
			}
			while (--fmtcnt >= 0) {
				switch (c = *fmt++) {
				case '-': flags |= F_LJUST; continue;
				case '+': flags |= F_SIGN; continue;
				case ' ': flags |= F_BLANK; continue;
				case '#': flags |= F_ALT; continue;
				case '0': flags |= F_ZERO; continue;
				}
				break;
			}
			if (c == '*') {
				v = getnextarg(args, arglen, &argidx);
				if (v == NULL)
					goto error;
				if (!PyInt_Check(v)) {
					PyErr_SetString(PyExc_TypeError,
							"* wants int");
					goto error;
				}
				width = PyInt_AsLong(v);
				if (width == -1 && PyErr_Occurred())
					goto error;
				if (width < 0) {
					flags |= F_LJUST;
					width = -width;
				}
				if (--fmtcnt >= 0)
					c = *fmt++;
			}
			else if (c >= 0 && isdigit(c)) {
				width = c - '0';
				while (--fmtcnt >= 0) {
					c = Py_CHARMASK(*fmt++);
					if (!isdigit(c))
						break;
					if ((width*10) / 10 != width) {
						PyErr_SetString(
							PyExc_ValueError,
							"width too big");
						goto error;
					}
					width = width*10 + (c - '0');
				}
			}
			if (c == '.') {
				prec = 0;
				if (--fmtcnt >= 0)
					c = *fmt++;
				if (c == '*') {
					v = getnextarg(args, arglen, &argidx);
					if (v == NULL)
						goto error;
					if (!PyInt_Check(v)) {
						PyErr_SetString(
							PyExc_TypeError,
							"* wants int");
						goto error;
					}
					prec = PyInt_AsLong(v);
					if (prec == -1 && PyErr_Occurred())
						goto error;
					if (prec < 0)
						prec = 0;
					if (--fmtcnt >= 0)
						c = *fmt++;
				}
				else if (c >= 0 && isdigit(c)) {
					prec = c - '0';
					while (--fmtcnt >= 0) {
						c = Py_CHARMASK(*fmt++);
						if (!isdigit(c))
							break;
						if ((prec*10) / 10 != prec) {
							PyErr_SetString(
							    PyExc_ValueError,
							    "prec too big");
							goto error;
						}
						prec = prec*10 + (c - '0');
					}
				}
			} /* prec */
			if (fmtcnt >= 0) {
				if (c == 'h' || c == 'l' || c == 'L') {
					if (--fmtcnt >= 0)
						c = *fmt++;
				}
			}
			if (fmtcnt < 0) {
				PyErr_SetString(PyExc_ValueError,
						"incomplete format");
				goto error;
			}
			if (c != '%') {
				v = getnextarg(args, arglen, &argidx);
				if (v == NULL)
					goto error;
			}
			sign = 0;
			fill = ' ';
			switch (c) {
			case '%':
				pbuf = "%";
				len = 1;
				break;
			case 's':
				if (PyUnicode_Check(v)) {
					fmt = fmt_start;
					argidx = argidx_start;
					goto unicode;
				}
				temp = _PyObject_Str(v);
				if (temp != NULL && PyUnicode_Check(temp)) {
					Py_DECREF(temp);
					fmt = fmt_start;
					argidx = argidx_start;
					goto unicode;
				}
				/* Fall through */
			case 'r':
				if (c == 'r')
					temp = PyObject_ReprStr8(v);
				if (temp == NULL)
					goto error;
				if (!PyString_Check(temp)) {
					PyErr_SetString(PyExc_TypeError,
					  "%s argument has non-string str()/repr()");
					Py_DECREF(temp);
					goto error;
				}
				pbuf = PyString_AS_STRING(temp);
				len = PyString_GET_SIZE(temp);
				if (prec >= 0 && len > prec)
					len = prec;
				break;
			case 'i':
			case 'd':
			case 'u':
			case 'o':
			case 'x':
			case 'X':
				if (c == 'i')
					c = 'd';
				if (PyLong_Check(v)) {
					int ilen;
					temp = _PyString_FormatLong(v, flags,
						prec, c, &pbuf, &ilen);
					len = ilen;
					if (!temp)
						goto error;
					sign = 1;
				}
				else {
					pbuf = formatbuf;
					len = formatint(pbuf,
							sizeof(formatbuf),
							flags, prec, c, v);
					if (len < 0)
						goto error;
					sign = 1;
				}
				if (flags & F_ZERO)
					fill = '0';
				break;
			case 'e':
			case 'E':
			case 'f':
			case 'F':
			case 'g':
			case 'G':
				if (c == 'F')
					c = 'f';
				pbuf = formatbuf;
				len = formatfloat(pbuf, sizeof(formatbuf),
						  flags, prec, c, v);
				if (len < 0)
					goto error;
				sign = 1;
				if (flags & F_ZERO)
					fill = '0';
				break;
			case 'c':
				if (PyUnicode_Check(v)) {
					fmt = fmt_start;
					argidx = argidx_start;
					goto unicode;
				}
				pbuf = formatbuf;
				len = formatchar(pbuf, sizeof(formatbuf), v);
				if (len < 0)
					goto error;
				break;
			default:
				PyErr_Format(PyExc_ValueError,
				  "unsupported format character '%c' (0x%x) "
				  "at index %zd",
				  c, c,
				  (Py_ssize_t)(fmt - 1 -
					       PyString_AsString(format)));
				goto error;
			}
			if (sign) {
				if (*pbuf == '-' || *pbuf == '+') {
					sign = *pbuf++;
					len--;
				}
				else if (flags & F_SIGN)
					sign = '+';
				else if (flags & F_BLANK)
					sign = ' ';
				else
					sign = 0;
			}
			if (width < len)
				width = len;
			if (rescnt - (sign != 0) < width) {
				reslen -= rescnt;
				rescnt = width + fmtcnt + 100;
				reslen += rescnt;
				if (reslen < 0) {
					Py_DECREF(result);
					Py_XDECREF(temp);
					return PyErr_NoMemory();
				}
				if (_PyString_Resize(&result, reslen) < 0) {
					Py_XDECREF(temp);
					return NULL;
				}
				res = PyString_AS_STRING(result)
					+ reslen - rescnt;
			}
			if (sign) {
				if (fill != ' ')
					*res++ = sign;
				rescnt--;
				if (width > len)
					width--;
			}
			if ((flags & F_ALT) && (c == 'x' || c == 'X')) {
				assert(pbuf[0] == '0');
				assert(pbuf[1] == c);
				if (fill != ' ') {
					*res++ = *pbuf++;
					*res++ = *pbuf++;
				}
				rescnt -= 2;
				width -= 2;
				if (width < 0)
					width = 0;
				len -= 2;
			}
			if (width > len && !(flags & F_LJUST)) {
				do {
					--rescnt;
					*res++ = fill;
				} while (--width > len);
			}
			if (fill == ' ') {
				if (sign)
					*res++ = sign;
				if ((flags & F_ALT) &&
				    (c == 'x' || c == 'X')) {
					assert(pbuf[0] == '0');
					assert(pbuf[1] == c);
					*res++ = *pbuf++;
					*res++ = *pbuf++;
				}
			}
			Py_MEMCPY(res, pbuf, len);
			res += len;
			rescnt -= len;
			while (--width >= len) {
				--rescnt;
				*res++ = ' ';
			}
                        if (dict && (argidx < arglen) && c != '%') {
                                PyErr_SetString(PyExc_TypeError,
                                           "not all arguments converted during string formatting");
                                Py_XDECREF(temp);
                                goto error;
                        }
			Py_XDECREF(temp);
		} /* '%' */
	} /* until end */
	if (argidx < arglen && !dict) {
		PyErr_SetString(PyExc_TypeError,
				"not all arguments converted during string formatting");
		goto error;
	}
	if (args_owned) {
		Py_DECREF(args);
	}
	_PyString_Resize(&result, reslen - rescnt);
	return result;

 unicode:
	if (args_owned) {
		Py_DECREF(args);
		args_owned = 0;
	}
	/* Fiddle args right (remove the first argidx arguments) */
	if (PyTuple_Check(orig_args) && argidx > 0) {
		PyObject *v;
		Py_ssize_t n = PyTuple_GET_SIZE(orig_args) - argidx;
		v = PyTuple_New(n);
		if (v == NULL)
			goto error;
		while (--n >= 0) {
			PyObject *w = PyTuple_GET_ITEM(orig_args, n + argidx);
			Py_INCREF(w);
			PyTuple_SET_ITEM(v, n, w);
		}
		args = v;
	} else {
		Py_INCREF(orig_args);
		args = orig_args;
	}
	args_owned = 1;
	/* Take what we have of the result and let the Unicode formatting
	   function format the rest of the input. */
	rescnt = res - PyString_AS_STRING(result);
	if (_PyString_Resize(&result, rescnt))
		goto error;
	fmtcnt = PyString_GET_SIZE(format) - \
		 (fmt - PyString_AS_STRING(format));
	format = PyUnicode_Decode(fmt, fmtcnt, NULL, NULL);
	if (format == NULL)
		goto error;
	v = PyUnicode_Format(format, args);
	Py_DECREF(format);
	if (v == NULL)
		goto error;
	/* Paste what we have (result) to what the Unicode formatting
	   function returned (v) and return the result (or error) */
	w = PyUnicode_Concat(result, v);
	Py_DECREF(result);
	Py_DECREF(v);
	Py_DECREF(args);
	return w;

 error:
	Py_DECREF(result);
	if (args_owned) {
		Py_DECREF(args);
	}
	return NULL;
}

void
PyString_InternInPlace(PyObject **p)
{
	register PyStringObject *s = (PyStringObject *)(*p);
	PyObject *t;
	if (s == NULL || !PyString_Check(s))
		Py_FatalError("PyString_InternInPlace: strings only please!");
	/* If it's a string subclass, we don't really know what putting
	   it in the interned dict might do. */
	if (!PyString_CheckExact(s))
		return;
	if (PyString_CHECK_INTERNED(s))
		return;
	if (interned == NULL) {
		interned = PyDict_New();
		if (interned == NULL) {
			PyErr_Clear(); /* Don't leave an exception */
			return;
		}
	}
	t = PyDict_GetItem(interned, (PyObject *)s);
	if (t) {
		Py_INCREF(t);
		Py_DECREF(*p);
		*p = t;
		return;
	}

	if (PyDict_SetItem(interned, (PyObject *)s, (PyObject *)s) < 0) {
		PyErr_Clear();
		return;
	}
	/* The two references in interned are not counted by refcnt.
	   The string deallocator will take care of this */
	s->ob_refcnt -= 2;
	PyString_CHECK_INTERNED(s) = SSTATE_INTERNED_MORTAL;
}

void
PyString_InternImmortal(PyObject **p)
{
	PyString_InternInPlace(p);
	if (PyString_CHECK_INTERNED(*p) != SSTATE_INTERNED_IMMORTAL) {
		PyString_CHECK_INTERNED(*p) = SSTATE_INTERNED_IMMORTAL;
		Py_INCREF(*p);
	}
}


PyObject *
PyString_InternFromString(const char *cp)
{
	PyObject *s = PyString_FromString(cp);
	if (s == NULL)
		return NULL;
	PyString_InternInPlace(&s);
	return s;
}

void
PyString_Fini(void)
{
	int i;
	for (i = 0; i < UCHAR_MAX + 1; i++) {
		Py_XDECREF(characters[i]);
		characters[i] = NULL;
	}
	Py_XDECREF(nullstring);
	nullstring = NULL;
}

void _Py_ReleaseInternedStrings(void)
{
	PyObject *keys;
	PyStringObject *s;
	Py_ssize_t i, n;
	Py_ssize_t immortal_size = 0, mortal_size = 0;

	if (interned == NULL || !PyDict_Check(interned))
		return;
	keys = PyDict_Keys(interned);
	if (keys == NULL || !PyList_Check(keys)) {
		PyErr_Clear();
		return;
	}

	/* Since _Py_ReleaseInternedStrings() is intended to help a leak
	   detector, interned strings are not forcibly deallocated; rather, we
	   give them their stolen references back, and then clear and DECREF
	   the interned dict. */

	n = PyList_GET_SIZE(keys);
	fprintf(stderr, "releasing %" PY_FORMAT_SIZE_T "d interned strings\n",
		n);
	for (i = 0; i < n; i++) {
		s = (PyStringObject *) PyList_GET_ITEM(keys, i);
		switch (s->ob_sstate) {
		case SSTATE_NOT_INTERNED:
			/* XXX Shouldn't happen */
			break;
		case SSTATE_INTERNED_IMMORTAL:
			s->ob_refcnt += 1;
			immortal_size += s->ob_size;
			break;
		case SSTATE_INTERNED_MORTAL:
			s->ob_refcnt += 2;
			mortal_size += s->ob_size;
			break;
		default:
			Py_FatalError("Inconsistent interned string state.");
		}
		s->ob_sstate = SSTATE_NOT_INTERNED;
	}
	fprintf(stderr, "total size of all interned strings: "
			"%" PY_FORMAT_SIZE_T "d/%" PY_FORMAT_SIZE_T "d "
			"mortal/immortal\n", mortal_size, immortal_size);
	Py_DECREF(keys);
	PyDict_Clear(interned);
	Py_DECREF(interned);
	interned = NULL;
}


/*********************** Str Iterator ****************************/

typedef struct {
	PyObject_HEAD
	Py_ssize_t it_index;
	PyStringObject *it_seq; /* Set to NULL when iterator is exhausted */
} striterobject;

static void
striter_dealloc(striterobject *it)
{
	_PyObject_GC_UNTRACK(it);
	Py_XDECREF(it->it_seq);
	PyObject_GC_Del(it);
}

static int
striter_traverse(striterobject *it, visitproc visit, void *arg)
{
	Py_VISIT(it->it_seq);
	return 0;
}

static PyObject *
striter_next(striterobject *it)
{
	PyStringObject *seq;
	PyObject *item;

	assert(it != NULL);
	seq = it->it_seq;
	if (seq == NULL)
		return NULL;
	assert(PyString_Check(seq));

	if (it->it_index < PyString_GET_SIZE(seq)) {
		item = PyString_FromStringAndSize(
			PyString_AS_STRING(seq)+it->it_index, 1);
		if (item != NULL)
			++it->it_index;
		return item;
	}

	Py_DECREF(seq);
	it->it_seq = NULL;
	return NULL;
}

static PyObject *
striter_len(striterobject *it)
{
	Py_ssize_t len = 0;
	if (it->it_seq)
		len = PyString_GET_SIZE(it->it_seq) - it->it_index;
	return PyInt_FromSsize_t(len);
}

PyDoc_STRVAR(length_hint_doc,
	     "Private method returning an estimate of len(list(it)).");

static PyMethodDef striter_methods[] = {
	{"__length_hint__", (PyCFunction)striter_len, METH_NOARGS,
	 length_hint_doc},
 	{NULL,		NULL}		/* sentinel */
};

PyTypeObject PyStringIter_Type = {
	PyObject_HEAD_INIT(&PyType_Type)
	0,					/* ob_size */
	"striterator",				/* tp_name */
	sizeof(striterobject),			/* tp_basicsize */
	0,					/* tp_itemsize */
	/* methods */
	(destructor)striter_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 | Py_TPFLAGS_HAVE_GC,/* tp_flags */
	0,					/* tp_doc */
	(traverseproc)striter_traverse,	/* tp_traverse */
	0,					/* tp_clear */
	0,					/* tp_richcompare */
	0,					/* tp_weaklistoffset */
	PyObject_SelfIter,			/* tp_iter */
	(iternextfunc)striter_next,		/* tp_iternext */
	striter_methods,			/* tp_methods */
	0,
};

static PyObject *
str_iter(PyObject *seq)
{
	striterobject *it;

	if (!PyString_Check(seq)) {
		PyErr_BadInternalCall();
		return NULL;
	}
	it = PyObject_GC_New(striterobject, &PyStringIter_Type);
	if (it == NULL)
		return NULL;
	it->it_index = 0;
	Py_INCREF(seq);
	it->it_seq = (PyStringObject *)seq;
	_PyObject_GC_TRACK(it);
	return (PyObject *)it;
}