Init_String(void)
{
#undef rb_intern
#define rb_intern(str) rb_intern_const(str)

    rb_cString  = rb_define_class("String", rb_cObject);
    rb_include_module(rb_cString, rb_mComparable);
    rb_define_alloc_func(rb_cString, str_alloc);
    rb_define_singleton_method(rb_cString, "try_convert", rb_str_s_try_convert, 1);
    rb_define_method(rb_cString, "initialize", rb_str_init, -1);
    rb_define_method(rb_cString, "initialize_copy", rb_str_replace, 1);
    rb_define_method(rb_cString, "<=>", rb_str_cmp_m, 1);
    rb_define_method(rb_cString, "==", rb_str_equal, 1);
    rb_define_method(rb_cString, "===", rb_str_equal, 1);
    rb_define_method(rb_cString, "eql?", rb_str_eql, 1);
    rb_define_method(rb_cString, "hash", rb_str_hash_m, 0);
    rb_define_method(rb_cString, "casecmp", rb_str_casecmp, 1);
    rb_define_method(rb_cString, "+", rb_str_plus, 1);
    rb_define_method(rb_cString, "*", rb_str_times, 1);
    rb_define_method(rb_cString, "%", rb_str_format_m, 1);
    rb_define_method(rb_cString, "[]", rb_str_aref_m, -1);
    rb_define_method(rb_cString, "[]=", rb_str_aset_m, -1);
    rb_define_method(rb_cString, "insert", rb_str_insert, 2);
    rb_define_method(rb_cString, "length", rb_str_length, 0);
    rb_define_method(rb_cString, "size", rb_str_length, 0);
    rb_define_method(rb_cString, "bytesize", rb_str_bytesize, 0);
    rb_define_method(rb_cString, "empty?", rb_str_empty, 0);
    rb_define_method(rb_cString, "=~", rb_str_match, 1);
    rb_define_method(rb_cString, "match", rb_str_match_m, -1);
    rb_define_method(rb_cString, "succ", rb_str_succ, 0);
    rb_define_method(rb_cString, "succ!", rb_str_succ_bang, 0);
    rb_define_method(rb_cString, "next", rb_str_succ, 0);
    rb_define_method(rb_cString, "next!", rb_str_succ_bang, 0);
    rb_define_method(rb_cString, "upto", rb_str_upto, -1);
    rb_define_method(rb_cString, "index", rb_str_index_m, -1);
    rb_define_method(rb_cString, "rindex", rb_str_rindex_m, -1);
    rb_define_method(rb_cString, "replace", rb_str_replace, 1);
    rb_define_method(rb_cString, "clear", rb_str_clear, 0);
    rb_define_method(rb_cString, "chr", rb_str_chr, 0);
    rb_define_method(rb_cString, "getbyte", rb_str_getbyte, 1);
    rb_define_method(rb_cString, "setbyte", rb_str_setbyte, 2);

    rb_define_method(rb_cString, "to_i", rb_str_to_i, -1);
    rb_define_method(rb_cString, "to_f", rb_str_to_f, 0);
    rb_define_method(rb_cString, "to_s", rb_str_to_s, 0);
    rb_define_method(rb_cString, "to_str", rb_str_to_s, 0);
    rb_define_method(rb_cString, "inspect", rb_str_inspect, 0);
    rb_define_method(rb_cString, "dump", rb_str_dump, 0);

    rb_define_method(rb_cString, "upcase", rb_str_upcase, 0);
    rb_define_method(rb_cString, "downcase", rb_str_downcase, 0);
    rb_define_method(rb_cString, "capitalize", rb_str_capitalize, 0);
    rb_define_method(rb_cString, "swapcase", rb_str_swapcase, 0);

    rb_define_method(rb_cString, "upcase!", rb_str_upcase_bang, 0);
    rb_define_method(rb_cString, "downcase!", rb_str_downcase_bang, 0);
    rb_define_method(rb_cString, "capitalize!", rb_str_capitalize_bang, 0);
    rb_define_method(rb_cString, "swapcase!", rb_str_swapcase_bang, 0);

    rb_define_method(rb_cString, "hex", rb_str_hex, 0);
    rb_define_method(rb_cString, "oct", rb_str_oct, 0);
    rb_define_method(rb_cString, "split", rb_str_split_m, -1);
    rb_define_method(rb_cString, "lines", rb_str_each_line, -1);
    rb_define_method(rb_cString, "bytes", rb_str_each_byte, 0);
    rb_define_method(rb_cString, "chars", rb_str_each_char, 0);
    rb_define_method(rb_cString, "codepoints", rb_str_each_codepoint, 0);
    rb_define_method(rb_cString, "reverse", rb_str_reverse, 0);
    rb_define_method(rb_cString, "reverse!", rb_str_reverse_bang, 0);
    rb_define_method(rb_cString, "concat", rb_str_concat, 1);
    rb_define_method(rb_cString, "<<", rb_str_concat, 1);
    rb_define_method(rb_cString, "crypt", rb_str_crypt, 1);
    rb_define_method(rb_cString, "intern", rb_str_intern, 0);
    rb_define_method(rb_cString, "to_sym", rb_str_intern, 0);
    rb_define_method(rb_cString, "ord", rb_str_ord, 0);

    rb_define_method(rb_cString, "include?", rb_str_include, 1);
    rb_define_method(rb_cString, "start_with?", rb_str_start_with, -1);
    rb_define_method(rb_cString, "end_with?", rb_str_end_with, -1);

    rb_define_method(rb_cString, "scan", rb_str_scan, 1);

    rb_define_method(rb_cString, "ljust", rb_str_ljust, -1);
    rb_define_method(rb_cString, "rjust", rb_str_rjust, -1);
    rb_define_method(rb_cString, "center", rb_str_center, -1);

    rb_define_method(rb_cString, "sub", rb_str_sub, -1);
    rb_define_method(rb_cString, "gsub", rb_str_gsub, -1);
    rb_define_method(rb_cString, "chop", rb_str_chop, 0);
    rb_define_method(rb_cString, "chomp", rb_str_chomp, -1);
    rb_define_method(rb_cString, "strip", rb_str_strip, 0);
    rb_define_method(rb_cString, "lstrip", rb_str_lstrip, 0);
    rb_define_method(rb_cString, "rstrip", rb_str_rstrip, 0);

    rb_define_method(rb_cString, "sub!", rb_str_sub_bang, -1);
    rb_define_method(rb_cString, "gsub!", rb_str_gsub_bang, -1);
    rb_define_method(rb_cString, "chop!", rb_str_chop_bang, 0);
    rb_define_method(rb_cString, "chomp!", rb_str_chomp_bang, -1);
    rb_define_method(rb_cString, "strip!", rb_str_strip_bang, 0);
    rb_define_method(rb_cString, "lstrip!", rb_str_lstrip_bang, 0);
    rb_define_method(rb_cString, "rstrip!", rb_str_rstrip_bang, 0);

    rb_define_method(rb_cString, "tr", rb_str_tr, 2);
    rb_define_method(rb_cString, "tr_s", rb_str_tr_s, 2);
    rb_define_method(rb_cString, "delete", rb_str_delete, -1);
    rb_define_method(rb_cString, "squeeze", rb_str_squeeze, -1);
    rb_define_method(rb_cString, "count", rb_str_count, -1);

    rb_define_method(rb_cString, "tr!", rb_str_tr_bang, 2);
    rb_define_method(rb_cString, "tr_s!", rb_str_tr_s_bang, 2);
    rb_define_method(rb_cString, "delete!", rb_str_delete_bang, -1);
    rb_define_method(rb_cString, "squeeze!", rb_str_squeeze_bang, -1);

    rb_define_method(rb_cString, "each_line", rb_str_each_line, -1);
    rb_define_method(rb_cString, "each_byte", rb_str_each_byte, 0);
    rb_define_method(rb_cString, "each_char", rb_str_each_char, 0);
    rb_define_method(rb_cString, "each_codepoint", rb_str_each_codepoint, 0);

    rb_define_method(rb_cString, "sum", rb_str_sum, -1);

    rb_define_method(rb_cString, "slice", rb_str_aref_m, -1);
    rb_define_method(rb_cString, "slice!", rb_str_slice_bang, -1);

    rb_define_method(rb_cString, "partition", rb_str_partition, 1);
    rb_define_method(rb_cString, "rpartition", rb_str_rpartition, 1);

    rb_define_method(rb_cString, "encoding", rb_obj_encoding, 0); /* in encoding.c */
    rb_define_method(rb_cString, "force_encoding", rb_str_force_encoding, 1);
    rb_define_method(rb_cString, "valid_encoding?", rb_str_valid_encoding_p, 0);
    rb_define_method(rb_cString, "ascii_only?", rb_str_is_ascii_only_p, 0);

    id_to_s = rb_intern("to_s");

    rb_fs = Qnil;
    rb_define_variable("$;", &rb_fs);
    rb_define_variable("$-F", &rb_fs);

    rb_cSymbol = rb_define_class("Symbol", rb_cObject);
    rb_include_module(rb_cSymbol, rb_mComparable);
    rb_undef_alloc_func(rb_cSymbol);
    rb_undef_method(CLASS_OF(rb_cSymbol), "new");
    rb_define_singleton_method(rb_cSymbol, "all_symbols", rb_sym_all_symbols, 0); /* in parse.y */

    rb_define_method(rb_cSymbol, "==", sym_equal, 1);
    rb_define_method(rb_cSymbol, "===", sym_equal, 1);
    rb_define_method(rb_cSymbol, "inspect", sym_inspect, 0);
    rb_define_method(rb_cSymbol, "to_s", rb_sym_to_s, 0);
    rb_define_method(rb_cSymbol, "id2name", rb_sym_to_s, 0);
    rb_define_method(rb_cSymbol, "intern", sym_to_sym, 0);
    rb_define_method(rb_cSymbol, "to_sym", sym_to_sym, 0);
    rb_define_method(rb_cSymbol, "to_proc", sym_to_proc, 0);
    rb_define_method(rb_cSymbol, "succ", sym_succ, 0);
    rb_define_method(rb_cSymbol, "next", sym_succ, 0);

    rb_define_method(rb_cSymbol, "<=>", sym_cmp, 1);
    rb_define_method(rb_cSymbol, "casecmp", sym_casecmp, 1);
    rb_define_method(rb_cSymbol, "=~", sym_match, 1);

    rb_define_method(rb_cSymbol, "[]", sym_aref, -1);
    rb_define_method(rb_cSymbol, "slice", sym_aref, -1);
    rb_define_method(rb_cSymbol, "length", sym_length, 0);
    rb_define_method(rb_cSymbol, "size", sym_length, 0);
    rb_define_method(rb_cSymbol, "empty?", sym_empty, 0);
    rb_define_method(rb_cSymbol, "match", sym_match, 1);

    rb_define_method(rb_cSymbol, "upcase", sym_upcase, 0);
    rb_define_method(rb_cSymbol, "downcase", sym_downcase, 0);
    rb_define_method(rb_cSymbol, "capitalize", sym_capitalize, 0);
    rb_define_method(rb_cSymbol, "swapcase", sym_swapcase, 0);

    rb_define_method(rb_cSymbol, "encoding", sym_encoding, 0);
}


* string.c (rb_str_justify): CVE-2009-4124.
  Fixes a bug reported by
  Emmanouel Kellinis <Emmanouel.Kellinis AT kpmg.co.uk>, KPMG London;
  Patch by nobu.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@26038 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

str_utf8_nth(const char *p, const char *e, long nth)
{
    if ((int)SIZEOF_VALUE < e - p && (int)SIZEOF_VALUE * 2 < nth) {
	const VALUE *s, *t;
	const VALUE lowbits = sizeof(VALUE) - 1;
	s = (const VALUE*)(~lowbits & ((VALUE)p + lowbits));
	t = (const VALUE*)(~lowbits & (VALUE)e);
	while (p < (const char *)s) {
	    if (is_utf8_lead_byte(*p)) nth--;
	    p++;
	}
	do {
	    nth -= count_utf8_lead_bytes_with_word(s);
	    s++;
	} while (s < t && (int)sizeof(VALUE) <= nth);
	p = (char *)s;
    }
    while (p < e) {
	if (is_utf8_lead_byte(*p)) {
	    if (nth == 0) break;
	    nth--;
	}
	p++;
    }
    return (char *)p;
}

Heap-based buffer overflow in the rb_str_justify function in string.c in Ruby 1.9.1 before 1.9.1-p376 allows context-dependent attackers to execute arbitrary code via unspecified vectors involving (1) String#ljust, (2) String#center, or (3) String#rjust.  NOTE: some of these details are obtained from third party information.


rb_str_check_dummy_enc(rb_encoding *enc)
{
    if (rb_enc_dummy_p(enc)) {
	rb_raise(rb_eEncCompatError, "incompatible encoding with this operation: %s",
		 rb_enc_name(enc));
    }
}


search_nonascii(const char *p, const char *e)
{
#if SIZEOF_VALUE == 8
# define NONASCII_MASK 0x8080808080808080LL
#elif SIZEOF_VALUE == 4
# define NONASCII_MASK 0x80808080UL
#endif
#ifdef NONASCII_MASK
    if ((int)sizeof(VALUE) * 2 < e - p) {
        const VALUE *s, *t;
        const VALUE lowbits = sizeof(VALUE) - 1;
        s = (const VALUE*)(~lowbits & ((VALUE)p + lowbits));
        while (p < (const char *)s) {
            if (!ISASCII(*p))
                return p;
            p++;
        }
        t = (const VALUE*)(~lowbits & (VALUE)e);
        while (s < t) {
            if (*s & NONASCII_MASK) {
                t = s;
                break;
            }
            s++;
        }
        p = (const char *)t;
    }
#endif
    while (p < e) {
        if (!ISASCII(*p))
            return p;
        p++;
    }
    return NULL;
}


rb_locale_str_new(const char *ptr, long len)
{
    return rb_external_str_new_with_enc(ptr, len, rb_locale_encoding());
}


rb_str_ljust(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'l');
}


rb_str_capitalize_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *send;
    int modify = 0;
    unsigned int c;
    int n;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    s = RSTRING_PTR(str); send = RSTRING_END(str);

    c = rb_enc_codepoint_len(s, send, &n, enc);
    if (rb_enc_islower(c, enc)) {
	rb_enc_mbcput(rb_enc_toupper(c, enc), s, enc);
	modify = 1;
    }
    s += n;
    while (s < send) {
	c = rb_enc_codepoint_len(s, send, &n, enc);
	if (rb_enc_isupper(c, enc)) {
	    rb_enc_mbcput(rb_enc_tolower(c, enc), s, enc);
	    modify = 1;
	}
	s += n;
    }

    if (modify) return str;
    return Qnil;
}


rb_str_init(int argc, VALUE *argv, VALUE str)
{
    VALUE orig;

    if (argc > 0 && rb_scan_args(argc, argv, "01", &orig) == 1)
	rb_str_replace(str, orig);
    return str;
}


rb_str_end_with(int argc, VALUE *argv, VALUE str)
{
    int i;
    char *p, *s, *e;
    rb_encoding *enc;

    for (i=0; i<argc; i++) {
	VALUE tmp = rb_check_string_type(argv[i]);
	if (NIL_P(tmp)) continue;
	enc = rb_enc_check(str, tmp);
	if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
	p = RSTRING_PTR(str);
        e = p + RSTRING_LEN(str);
	s = e - RSTRING_LEN(tmp);
	if (rb_enc_left_char_head(p, s, e, enc) != s)
	    continue;
	if (memcmp(s, RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
	    return Qtrue;
    }
    return Qfalse;
}


rb_str_shared_replace(VALUE str, VALUE str2)
{
    rb_encoding *enc;
    int cr;
    if (str == str2) return;
    enc = STR_ENC_GET(str2);
    cr = ENC_CODERANGE(str2);
    str_discard(str);
    OBJ_INFECT(str, str2);
    if (RSTRING_LEN(str2) <= RSTRING_EMBED_LEN_MAX) {
	STR_SET_EMBED(str);
	memcpy(RSTRING_PTR(str), RSTRING_PTR(str2), RSTRING_LEN(str2)+1);
	STR_SET_EMBED_LEN(str, RSTRING_LEN(str2));
        rb_enc_associate(str, enc);
        ENC_CODERANGE_SET(str, cr);
	return;
    }
    STR_SET_NOEMBED(str);
    STR_UNSET_NOCAPA(str);
    RSTRING(str)->as.heap.ptr = RSTRING_PTR(str2);
    RSTRING(str)->as.heap.len = RSTRING_LEN(str2);
    if (STR_NOCAPA_P(str2)) {
	FL_SET(str, RBASIC(str2)->flags & STR_NOCAPA);
	RSTRING(str)->as.heap.aux.shared = RSTRING(str2)->as.heap.aux.shared;
    }
    else {
	RSTRING(str)->as.heap.aux.capa = RSTRING(str2)->as.heap.aux.capa;
    }
    STR_SET_EMBED(str2);	/* abandon str2 */
    RSTRING_PTR(str2)[0] = 0;
    STR_SET_EMBED_LEN(str2, 0);
    rb_enc_associate(str, enc);
    ENC_CODERANGE_SET(str, cr);
}


rb_filesystem_str_new_cstr(const char *ptr)
{
    return rb_external_str_new_with_enc(ptr, strlen(ptr), rb_filesystem_encoding());
}


enc_strlen(const char *p, const char *e, rb_encoding *enc, int cr)
{
    long c;
    const char *q;

    if (rb_enc_mbmaxlen(enc) == rb_enc_mbminlen(enc)) {
        return (e - p + rb_enc_mbminlen(enc) - 1) / rb_enc_mbminlen(enc);
    }
    else if (rb_enc_asciicompat(enc)) {
        c = 0;
	if (cr == ENC_CODERANGE_7BIT || cr == ENC_CODERANGE_VALID) {
	    while (p < e) {
		if (ISASCII(*p)) {
		    q = search_nonascii(p, e);
		    if (!q)
			return c + (e - p);
		    c += q - p;
		    p = q;
		}
		p += rb_enc_fast_mbclen(p, e, enc);
		c++;
	    }
	}
	else {
	    while (p < e) {
		if (ISASCII(*p)) {
		    q = search_nonascii(p, e);
		    if (!q)
			return c + (e - p);
		    c += q - p;
		    p = q;
		}
		p += rb_enc_mbclen(p, e, enc);
		c++;
	    }
	}
        return c;
    }

    for (c=0; p<e; c++) {
        p += rb_enc_mbclen(p, e, enc);
    }
    return c;
}


rb_str_subpat_set(VALUE str, VALUE re, VALUE backref, VALUE val)
{
    int nth;
    VALUE match;
    long start, end, len;
    rb_encoding *enc;
    struct re_registers *regs;

    if (rb_reg_search(re, str, 0, 0) < 0) {
	rb_raise(rb_eIndexError, "regexp not matched");
    }
    match = rb_backref_get();
    nth = rb_reg_backref_number(match, backref);
    regs = RMATCH_REGS(match);
    if (nth >= regs->num_regs) {
      out_of_range:
	rb_raise(rb_eIndexError, "index %d out of regexp", nth);
    }
    if (nth < 0) {
	if (-nth >= regs->num_regs) {
	    goto out_of_range;
	}
	nth += regs->num_regs;
    }

    start = BEG(nth);
    if (start == -1) {
	rb_raise(rb_eIndexError, "regexp group %d not matched", nth);
    }
    end = END(nth);
    len = end - start;
    StringValue(val);
    enc = rb_enc_check(str, val);
    rb_str_splice_0(str, start, len, val);
    rb_enc_associate(str, enc);
}


rb_str_format_m(VALUE str, VALUE arg)
{
    volatile VALUE tmp = rb_check_array_type(arg);

    if (!NIL_P(tmp)) {
	return rb_str_format(RARRAY_LENINT(tmp), RARRAY_PTR(tmp), str);
    }
    return rb_str_format(1, &arg, str);
}


sym_to_sym(VALUE sym)
{
    return sym;
}


str_replace(VALUE str, VALUE str2)
{
    long len;

    len = RSTRING_LEN(str2);
    if (STR_ASSOC_P(str2)) {
	str2 = rb_str_new4(str2);
    }
    if (STR_SHARED_P(str2)) {
	VALUE shared = RSTRING(str2)->as.heap.aux.shared;
	assert(OBJ_FROZEN(shared));
	STR_SET_NOEMBED(str);
	RSTRING(str)->as.heap.len = len;
	RSTRING(str)->as.heap.ptr = RSTRING_PTR(str2);
	FL_SET(str, ELTS_SHARED);
	FL_UNSET(str, STR_ASSOC);
	RSTRING(str)->as.heap.aux.shared = shared;
    }
    else {
	str_replace_shared(str, str2);
    }

    OBJ_INFECT(str, str2);
    rb_enc_cr_str_exact_copy(str, str2);
    return str;
}


rb_str_sublen(VALUE str, long pos)
{
    if (single_byte_optimizable(str) || pos < 0)
        return pos;
    else {
	char *p = RSTRING_PTR(str);
        return enc_strlen(p, p + pos, STR_ENC_GET(str), ENC_CODERANGE(str));
    }
}


rb_str_to_str(VALUE str)
{
    return rb_convert_type(str, T_STRING, "String", "to_str");
}


rb_str_hash_cmp(VALUE str1, VALUE str2)
{
    long len;

    if (!rb_str_comparable(str1, str2)) return 1;
    if (RSTRING_LEN(str1) == (len = RSTRING_LEN(str2)) &&
	memcmp(RSTRING_PTR(str1), RSTRING_PTR(str2), len) == 0) {
	return 0;
    }
    return 1;
}


rb_str_squeeze_bang(int argc, VALUE *argv, VALUE str)
{
    char squeez[256];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0;
    char *s, *send, *t;
    int i, modify = 0;
    int ascompat, singlebyte = single_byte_optimizable(str);
    unsigned int save;

    if (argc == 0) {
	enc = STR_ENC_GET(str);
    }
    else {
	for (i=0; i<argc; i++) {
	    VALUE s = argv[i];

	    StringValue(s);
	    enc = rb_enc_check(str, s);
	    if (singlebyte && !single_byte_optimizable(s))
		singlebyte = 0;
	    tr_setup_table(s, squeez, i==0, &del, &nodel, enc);
	}
    }

    str_modify_keep_cr(str);
    s = t = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    send = RSTRING_END(str);
    save = -1;
    ascompat = rb_enc_asciicompat(enc);

    if (singlebyte) {
        while (s < send) {
	    unsigned int c = *(unsigned char*)s++;
	    if (c != save || (argc > 0 && !squeez[c])) {
	        *t++ = save = c;
	    }
	}
    } else {
	while (s < send) {
	    unsigned int c;
	    int clen;

	    if (ascompat && (c = *(unsigned char*)s) < 0x80) {
		if (c != save || (argc > 0 && !squeez[c])) {
		    *t++ = save = c;
		}
		s++;
	    }
	    else {
		c = rb_enc_codepoint_len(s, send, &clen, enc);

		if (c != save || (argc > 0 && !tr_find(c, squeez, del, nodel))) {
		    if (t != s) rb_enc_mbcput(c, t, enc);
		    save = c;
		    t += clen;
		}
		s += clen;
	    }
	}
    }

    *t = '\0';
    if (t - RSTRING_PTR(str) != RSTRING_LEN(str)) {
	STR_SET_LEN(str, t - RSTRING_PTR(str));
	modify = 1;
    }

    if (modify) return str;
    return Qnil;
}


str_new_shared(VALUE klass, VALUE str)
{
    return str_replace_shared(str_alloc(klass), str);
}


rb_str_match(VALUE x, VALUE y)
{
    switch (TYPE(y)) {
      case T_STRING:
	rb_raise(rb_eTypeError, "type mismatch: String given");

      case T_REGEXP:
	return rb_reg_match(y, x);

      default:
	return rb_funcall(y, rb_intern("=~"), 1, x);
    }
}


rb_str_upcase_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *send;
    int modify = 0;
    int n;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    s = RSTRING_PTR(str); send = RSTRING_END(str);
    if (single_byte_optimizable(str)) {
	while (s < send) {
	    unsigned int c = *(unsigned char*)s;

	    if (rb_enc_isascii(c, enc) && 'a' <= c && c <= 'z') {
		*s = 'A' + (c - 'a');
		modify = 1;
	    }
	    s++;
	}
    }
    else {
	int ascompat = rb_enc_asciicompat(enc);

	while (s < send) {
	    unsigned int c;

	    if (ascompat && (c = *(unsigned char*)s) < 0x80) {
		if (rb_enc_isascii(c, enc) && 'a' <= c && c <= 'z') {
		    *s = 'A' + (c - 'a');
		    modify = 1;
		}
		s++;
	    }
	    else {
		c = rb_enc_codepoint_len(s, send, &n, enc);
		if (rb_enc_islower(c, enc)) {
		    /* assuming toupper returns codepoint with same size */
		    rb_enc_mbcput(rb_enc_toupper(c, enc), s, enc);
		    modify = 1;
		}
		s += n;
	    }
	}
    }

    if (modify) return str;
    return Qnil;
}


rb_str_freeze(VALUE str)
{
    if (STR_ASSOC_P(str)) {
	VALUE ary = RSTRING(str)->as.heap.aux.shared;
	OBJ_FREEZE(ary);
    }
    return rb_obj_freeze(str);
}


rb_str_setbyte(VALUE str, VALUE index, VALUE value)
{
    long pos = NUM2LONG(index);
    int byte = NUM2INT(value);

    rb_str_modify(str);

    if (pos < -RSTRING_LEN(str) || RSTRING_LEN(str) <= pos)
        rb_raise(rb_eIndexError, "index %ld out of string", pos);
    if (pos < 0)
        pos += RSTRING_LEN(str);

    RSTRING_PTR(str)[pos] = byte;

    return value;
}


rb_str_valid_encoding_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return cr == ENC_CODERANGE_BROKEN ? Qfalse : Qtrue;
}


rb_str_hash_m(VALUE str)
{
    st_index_t hval = rb_str_hash(str);
    return INT2FIX(hval);
}


rb_external_str_new_with_enc(const char *ptr, long len, rb_encoding *eenc)
{
    VALUE str;

    str = rb_tainted_str_new(ptr, len);
    if (eenc == rb_usascii_encoding() &&
	rb_enc_str_coderange(str) != ENC_CODERANGE_7BIT) {
	rb_enc_associate(str, rb_ascii8bit_encoding());
	return str;
    }
    rb_enc_associate(str, eenc);
    return rb_str_conv_enc(str, eenc, rb_default_internal_encoding());
}


rb_enc_str_new(const char *ptr, long len, rb_encoding *enc)
{
    VALUE str = rb_str_new(ptr, len);
    rb_enc_associate(str, enc);
    return str;
}


rb_enc_nth(const char *p, const char *e, long nth, rb_encoding *enc)
{
    if (rb_enc_mbmaxlen(enc) == 1) {
        p += nth;
    }
    else if (rb_enc_mbmaxlen(enc) == rb_enc_mbminlen(enc)) {
        p += nth * rb_enc_mbmaxlen(enc);
    }
    else if (rb_enc_asciicompat(enc)) {
        const char *p2, *e2;
        int n;

        while (p < e && 0 < nth) {
            e2 = p + nth;
            if (e < e2)
                return (char *)e;
            if (ISASCII(*p)) {
                p2 = search_nonascii(p, e2);
                if (!p2)
                    return (char *)e2;
                nth -= p2 - p;
                p = p2;
            }
            n = rb_enc_mbclen(p, e, enc);
            p += n;
            nth--;
        }
        if (nth != 0)
            return (char *)e;
        return (char *)p;
    }
    else {
        while (p<e && nth--) {
            p += rb_enc_mbclen(p, e, enc);
        }
    }
    if (p > e) p = e;
    return (char*)p;
}


rb_str_insert(VALUE str, VALUE idx, VALUE str2)
{
    long pos = NUM2LONG(idx);

    if (pos == -1) {
	return rb_str_append(str, str2);
    }
    else if (pos < 0) {
	pos++;
    }
    rb_str_splice(str, pos, 0, str2);
    return str;
}


rb_enc_str_buf_cat(VALUE str, const char *ptr, long len, rb_encoding *ptr_enc)
{
    return rb_enc_cr_str_buf_cat(str, ptr, len,
        rb_enc_to_index(ptr_enc), ENC_CODERANGE_UNKNOWN, NULL);
}


sym_upcase(VALUE sym)
{
    return rb_str_intern(rb_str_upcase(rb_id2str(SYM2ID(sym))));
}


rb_str_chop_bang(VALUE str)
{
    str_modify_keep_cr(str);
    if (RSTRING_LEN(str) > 0) {
	long len;
	len = chopped_length(str);
	STR_SET_LEN(str, len);
	RSTRING_PTR(str)[len] = '\0';
	if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
	    ENC_CODERANGE_CLEAR(str);
	}
	return str;
    }
    return Qnil;
}


rb_str_force_encoding(VALUE str, VALUE enc)
{
    str_modifiable(str);
    rb_enc_associate(str, rb_to_encoding(enc));
    ENC_CODERANGE_CLEAR(str);
    return str;
}


rb_enc_strlen_cr(const char *p, const char *e, rb_encoding *enc, int *cr)
{
    long c;
    const char *q;
    int ret;

    *cr = 0;
    if (rb_enc_mbmaxlen(enc) == rb_enc_mbminlen(enc)) {
	return (e - p + rb_enc_mbminlen(enc) - 1) / rb_enc_mbminlen(enc);
    }
    else if (rb_enc_asciicompat(enc)) {
	c = 0;
	while (p < e) {
	    if (ISASCII(*p)) {
		q = search_nonascii(p, e);
		if (!q) {
		    if (!*cr) *cr = ENC_CODERANGE_7BIT;
		    return c + (e - p);
		}
		c += q - p;
		p = q;
	    }
	    ret = rb_enc_precise_mbclen(p, e, enc);
	    if (MBCLEN_CHARFOUND_P(ret)) {
		*cr |= ENC_CODERANGE_VALID;
		p += MBCLEN_CHARFOUND_LEN(ret);
	    }
	    else {
		*cr = ENC_CODERANGE_BROKEN;
		p++;
	    }
	    c++;
	}
	if (!*cr) *cr = ENC_CODERANGE_7BIT;
	return c;
    }

    for (c=0; p<e; c++) {
	ret = rb_enc_precise_mbclen(p, e, enc);
	if (MBCLEN_CHARFOUND_P(ret)) {
	    *cr |= ENC_CODERANGE_VALID;
	    p += MBCLEN_CHARFOUND_LEN(ret);
	}
	else {
	    *cr = ENC_CODERANGE_BROKEN;
	    p++;
	}
    }
    if (!*cr) *cr = ENC_CODERANGE_7BIT;
    return c;
}


rb_str_conv_enc(VALUE str, rb_encoding *from, rb_encoding *to)
{
    return rb_str_conv_enc_opts(str, from, to, 0, Qnil);
}


rb_str_update(VALUE str, long beg, long len, VALUE val)
{
    rb_str_splice(str, beg, len, val);
}


rb_str_buf_cat(VALUE str, const char *ptr, long len)
{
    if (len == 0) return str;
    if (len < 0) {
	rb_raise(rb_eArgError, "negative string size (or size too big)");
    }
    return str_buf_cat(str, ptr, len);
}


rb_str_buf_new(long capa)
{
    VALUE str = str_alloc(rb_cString);

    if (capa < STR_BUF_MIN_SIZE) {
	capa = STR_BUF_MIN_SIZE;
    }
    FL_SET(str, STR_NOEMBED);
    RSTRING(str)->as.heap.aux.capa = capa;
    RSTRING(str)->as.heap.ptr = ALLOC_N(char, capa+1);
    RSTRING(str)->as.heap.ptr[0] = '\0';

    return str;
}


rb_str_to_f(VALUE str)
{
    return DBL2NUM(rb_str_to_dbl(str, FALSE));
}


rb_str_replace(VALUE str, VALUE str2)
{
    if (str == str2) return str;

    StringValue(str2);
    str_discard(str);
    return str_replace(str, str2);
}


tr_trans(VALUE str, VALUE src, VALUE repl, int sflag)
{
    const unsigned int errc = -1;
    unsigned int trans[256];
    rb_encoding *enc, *e1, *e2;
    struct tr trsrc, trrepl;
    int cflag = 0;
    unsigned int c, c0;
    int last = 0, modify = 0, i, l;
    char *s, *send;
    VALUE hash = 0;
    int singlebyte = single_byte_optimizable(str);
    int cr;

#define CHECK_IF_ASCII(c) \
    (void)((cr == ENC_CODERANGE_7BIT && !rb_isascii(c)) ? \
	   (cr = ENC_CODERANGE_VALID) : 0)

    StringValue(src);
    StringValue(repl);
    if (RSTRING_LEN(str) == 0 || !RSTRING_PTR(str)) return Qnil;
    if (RSTRING_LEN(repl) == 0) {
	return rb_str_delete_bang(1, &src, str);
    }

    cr = ENC_CODERANGE(str);
    e1 = rb_enc_check(str, src);
    e2 = rb_enc_check(str, repl);
    if (e1 == e2) {
	enc = e1;
    }
    else {
	enc = rb_enc_check(src, repl);
    }
    trsrc.p = RSTRING_PTR(src); trsrc.pend = trsrc.p + RSTRING_LEN(src);
    if (RSTRING_LEN(src) > 1 &&
	rb_enc_ascget(trsrc.p, trsrc.pend, &l, enc) == '^' &&
	trsrc.p + l < trsrc.pend) {
	cflag = 1;
	trsrc.p += l;
    }
    trrepl.p = RSTRING_PTR(repl);
    trrepl.pend = trrepl.p + RSTRING_LEN(repl);
    trsrc.gen = trrepl.gen = 0;
    trsrc.now = trrepl.now = 0;
    trsrc.max = trrepl.max = 0;

    if (cflag) {
	for (i=0; i<256; i++) {
	    trans[i] = 1;
	}
	while ((c = trnext(&trsrc, enc)) != errc) {
	    if (c < 256) {
		trans[c] = errc;
	    }
	    else {
		if (!hash) hash = rb_hash_new();
		rb_hash_aset(hash, UINT2NUM(c), Qtrue);
	    }
	}
	while ((c = trnext(&trrepl, enc)) != errc)
	    /* retrieve last replacer */;
	last = trrepl.now;
	for (i=0; i<256; i++) {
	    if (trans[i] != errc) {
		trans[i] = last;
	    }
	}
    }
    else {
	unsigned int r;

	for (i=0; i<256; i++) {
	    trans[i] = errc;
	}
	while ((c = trnext(&trsrc, enc)) != errc) {
	    r = trnext(&trrepl, enc);
	    if (r == errc) r = trrepl.now;
	    if (c < 256) {
		trans[c] = r;
		if (rb_enc_codelen(r, enc) != 1) singlebyte = 0;
	    }
	    else {
		if (!hash) hash = rb_hash_new();
		rb_hash_aset(hash, UINT2NUM(c), UINT2NUM(r));
	    }
	}
    }

    if (cr == ENC_CODERANGE_VALID)
	cr = ENC_CODERANGE_7BIT;
    str_modify_keep_cr(str);
    s = RSTRING_PTR(str); send = RSTRING_END(str);
    if (sflag) {
	int clen, tlen;
	long offset, max = RSTRING_LEN(str);
	unsigned int save = -1;
	char *buf = ALLOC_N(char, max), *t = buf;

	while (s < send) {
	    int may_modify = 0;

	    c0 = c = rb_enc_codepoint_len(s, send, &clen, e1);
	    tlen = enc == e1 ? clen : rb_enc_codelen(c, enc);

	    s += clen;
	    if (c < 256) {
		c = trans[c];
	    }
	    else if (hash) {
		VALUE tmp = rb_hash_lookup(hash, UINT2NUM(c));
		if (NIL_P(tmp)) {
		    if (cflag) c = last;
		    else c = errc;
		}
		else if (cflag) c = errc;
		else c = NUM2INT(tmp);
	    }
	    else {
		c = errc;
	    }
	    if (c != (unsigned int)-1) {
		if (save == c) {
		    CHECK_IF_ASCII(c);
		    continue;
		}
		save = c;
		tlen = rb_enc_codelen(c, enc);
		modify = 1;
	    }
	    else {
		save = -1;
		c = c0;
		if (enc != e1) may_modify = 1;
	    }
	    while (t - buf + tlen >= max) {
		offset = t - buf;
		max *= 2;
		REALLOC_N(buf, char, max);
		t = buf + offset;
	    }
	    rb_enc_mbcput(c, t, enc);
	    if (may_modify && memcmp(s, t, tlen) != 0) {
		modify = 1;
	    }
	    CHECK_IF_ASCII(c);
	    t += tlen;
	}
	*t = '\0';
	RSTRING(str)->as.heap.ptr = buf;
	RSTRING(str)->as.heap.len = t - buf;
	STR_SET_NOEMBED(str);
	RSTRING(str)->as.heap.aux.capa = max;
    }
    else if (rb_enc_mbmaxlen(enc) == 1 || (singlebyte && !hash)) {
	while (s < send) {
	    c = (unsigned char)*s;
	    if (trans[c] != errc) {
		if (!cflag) {
		    c = trans[c];
		    *s = c;
		    modify = 1;
		}
		else {
		    *s = last;
		    modify = 1;
		}
	    }
	    CHECK_IF_ASCII(c);
	    s++;
	}
    }
    else {
	int clen, tlen, max = (int)(RSTRING_LEN(str) * 1.2);
	long offset;
	char *buf = ALLOC_N(char, max), *t = buf;

	while (s < send) {
	    int may_modify = 0;
	    c0 = c = rb_enc_codepoint_len(s, send, &clen, e1);
	    tlen = enc == e1 ? clen : rb_enc_codelen(c, enc);

	    if (c < 256) {
		c = trans[c];
	    }
	    else if (hash) {
		VALUE tmp = rb_hash_lookup(hash, UINT2NUM(c));
		if (NIL_P(tmp)) {
		    if (cflag) c = last;
		    else c = errc;
		}
		else if (cflag) c = errc;
		else c = NUM2INT(tmp);
	    }
	    else {
		c = errc;
	    }
	    if (c != errc) {
		tlen = rb_enc_codelen(c, enc);
		modify = 1;
	    }
	    else {
		c = c0;
		if (enc != e1) may_modify = 1;
	    }
	    while (t - buf + tlen >= max) {
		offset = t - buf;
		max *= 2;
		REALLOC_N(buf, char, max);
		t = buf + offset;
	    }
	    if (s != t) {
		rb_enc_mbcput(c, t, enc);
		if (may_modify && memcmp(s, t, tlen) != 0) {
		    modify = 1;
		}
	    }
	    CHECK_IF_ASCII(c);
	    s += clen;
	    t += tlen;
	}
	if (!STR_EMBED_P(str)) {
	    xfree(RSTRING(str)->as.heap.ptr);
	}
	*t = '\0';
	RSTRING(str)->as.heap.ptr = buf;
	RSTRING(str)->as.heap.len = t - buf;
	STR_SET_NOEMBED(str);
	RSTRING(str)->as.heap.aux.capa = max;
    }

    if (modify) {
	if (cr != ENC_CODERANGE_BROKEN)
	    ENC_CODERANGE_SET(str, cr);
	rb_enc_associate(str, enc);
	return str;
    }
    return Qnil;
}


rb_str_slice_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE result;
    VALUE buf[3];
    int i;

    if (argc < 1 || 2 < argc) {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 1)", argc);
    }
    for (i=0; i<argc; i++) {
	buf[i] = argv[i];
    }
    str_modify_keep_cr(str);
    buf[i] = rb_str_new(0,0);
    result = rb_str_aref_m(argc, buf, str);
    if (!NIL_P(result)) {
	rb_str_aset_m(argc+1, buf, str);
    }
    return result;
}


rb_str_each_codepoint(VALUE str)
{
    VALUE orig = str;
    long len;
    int n;
    unsigned int c;
    const char *ptr, *end;
    rb_encoding *enc;

    if (single_byte_optimizable(str)) return rb_str_each_byte(str);
    RETURN_ENUMERATOR(str, 0, 0);
    str = rb_str_new4(str);
    ptr = RSTRING_PTR(str);
    len = RSTRING_LEN(str);
    end = RSTRING_END(str);
    enc = STR_ENC_GET(str);
    while (ptr < end) {
	c = rb_enc_codepoint_len(ptr, end, &n, enc);
	rb_yield(UINT2NUM(c));
	ptr += n;
    }
    return orig;
}


rb_str_squeeze(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    rb_str_squeeze_bang(argc, argv, str);
    return str;
}


rb_str_lstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *t, *e;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    e = t = RSTRING_END(str);
    /* remove spaces at head */
    while (s < e) {
	int n;
	unsigned int cc = rb_enc_codepoint_len(s, e, &n, enc);

	if (!rb_isspace(cc)) break;
	s += n;
    }

    if (s > RSTRING_PTR(str)) {
	STR_SET_LEN(str, t-s);
	memmove(RSTRING_PTR(str), s, RSTRING_LEN(str));
	RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
	return str;
    }
    return Qnil;
}


rb_str_hash(VALUE str)
{
    int e = ENCODING_GET(str);
    if (e && rb_enc_str_coderange(str) == ENC_CODERANGE_7BIT) {
	e = 0;
    }
    return rb_memhash((const void *)RSTRING_PTR(str), RSTRING_LEN(str)) ^ e;
}


rb_filesystem_str_new(const char *ptr, long len)
{
    return rb_external_str_new_with_enc(ptr, len, rb_filesystem_encoding());
}


rb_str_new_with_class(VALUE obj, const char *ptr, long len)
{
    return str_new(rb_obj_class(obj), ptr, len);
}


str_discard(VALUE str)
{
    str_modifiable(str);
    if (!STR_SHARED_P(str) && !STR_EMBED_P(str)) {
	xfree(RSTRING_PTR(str));
	RSTRING(str)->as.heap.ptr = 0;
	RSTRING(str)->as.heap.len = 0;
    }
}


rb_str_reverse(VALUE str)
{
    rb_encoding *enc;
    VALUE rev;
    char *s, *e, *p;
    int single = 1;

    if (RSTRING_LEN(str) <= 1) return rb_str_dup(str);
    enc = STR_ENC_GET(str);
    rev = rb_str_new5(str, 0, RSTRING_LEN(str));
    s = RSTRING_PTR(str); e = RSTRING_END(str);
    p = RSTRING_END(rev);

    if (RSTRING_LEN(str) > 1) {
	if (single_byte_optimizable(str)) {
	    while (s < e) {
		*--p = *s++;
	    }
	}
	else if (ENC_CODERANGE(str) == ENC_CODERANGE_VALID) {
	    while (s < e) {
		int clen = rb_enc_fast_mbclen(s, e, enc);

		if (clen > 1 || (*s & 0x80)) single = 0;
		p -= clen;
		memcpy(p, s, clen);
		s += clen;
	    }
	}
	else {
	    while (s < e) {
		int clen = rb_enc_mbclen(s, e, enc);

		if (clen > 1 || (*s & 0x80)) single = 0;
		p -= clen;
		memcpy(p, s, clen);
		s += clen;
	    }
	}
    }
    STR_SET_LEN(rev, RSTRING_LEN(str));
    OBJ_INFECT(rev, str);
    if (ENC_CODERANGE(str) == ENC_CODERANGE_UNKNOWN) {
	if (single) {
	    ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
	}
	else {
	    ENC_CODERANGE_SET(str, ENC_CODERANGE_VALID);
	}
    }
    rb_enc_cr_str_copy_for_substr(rev, str);

    return rev;
}


rb_str_tr_s_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 1);
}


trnext(struct tr *t, rb_encoding *enc)
{
    int n;

    for (;;) {
	if (!t->gen) {
	    if (t->p == t->pend) return -1;
	    if (t->p < t->pend - 1 && *t->p == '\\') {
		t->p++;
	    }
	    t->now = rb_enc_codepoint_len(t->p, t->pend, &n, enc);
	    t->p += n;
	    if (t->p < t->pend - 1 && *t->p == '-') {
		t->p++;
		if (t->p < t->pend) {
		    unsigned int c = rb_enc_codepoint_len(t->p, t->pend, &n, enc);
		    t->p += n;
		    if (t->now > c) {
			if (t->now < 0x80 && c < 0x80) {
			    rb_raise(rb_eArgError,
				     "invalid range \"%c-%c\" in string transliteration",
				     t->now, c);
			}
			else {
			    rb_raise(rb_eArgError, "invalid range in string transliteration");
			}
			continue; /* not reached */
		    }
		    t->gen = 1;
		    t->max = c;
		}
	    }
	    return t->now;
	}
	else if (++t->now < t->max) {
	    return t->now;
	}
	else {
	    t->gen = 0;
	    return t->max;
	}
    }
}


rb_str_rpartition(VALUE str, VALUE sep)
{
    long pos = RSTRING_LEN(str);
    int regex = FALSE;

    if (TYPE(sep) == T_REGEXP) {
	pos = rb_reg_search(sep, str, pos, 1);
	regex = TRUE;
    }
    else {
	VALUE tmp;

	tmp = rb_check_string_type(sep);
	if (NIL_P(tmp)) {
	    rb_raise(rb_eTypeError, "type mismatch: %s given",
		     rb_obj_classname(sep));
	}
	sep = tmp;
	pos = rb_str_sublen(str, pos);
	pos = rb_str_rindex(str, sep, pos);
    }
    if (pos < 0) {
	return rb_ary_new3(3, rb_str_new(0,0),rb_str_new(0,0), str);
    }
    if (regex) {
	sep = rb_reg_nth_match(0, rb_backref_get());
    }
    return rb_ary_new3(3, rb_str_substr(str, 0, pos),
		          sep,
		          rb_str_substr(str,pos+str_strlen(sep,STR_ENC_GET(sep)),RSTRING_LEN(str)));
}


rb_str_new(const char *ptr, long len)
{
    return str_new(rb_cString, ptr, len);
}


rb_str_setter(VALUE val, ID id, VALUE *var)
{
    if (!NIL_P(val) && TYPE(val) != T_STRING) {
	rb_raise(rb_eTypeError, "value of %s must be String", rb_id2name(id));
    }
    *var = val;
}


rb_str_upcase(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_upcase_bang(str);
    return str;
}


rb_str_cmp_m(VALUE str1, VALUE str2)
{
    long result;

    if (TYPE(str2) != T_STRING) {
	if (!rb_respond_to(str2, rb_intern("to_str"))) {
	    return Qnil;
	}
	else if (!rb_respond_to(str2, rb_intern("<=>"))) {
	    return Qnil;
	}
	else {
	    VALUE tmp = rb_funcall(str2, rb_intern("<=>"), 1, str1);

	    if (NIL_P(tmp)) return Qnil;
	    if (!FIXNUM_P(tmp)) {
		return rb_funcall(LONG2FIX(0), '-', 1, tmp);
	    }
	    result = -FIX2LONG(tmp);
	}
    }
    else {
	result = rb_str_cmp(str1, str2);
    }
    return LONG2NUM(result);
}


rb_enc_cr_str_exact_copy(VALUE dest, VALUE src)
{
    str_enc_copy(dest, src);
    ENC_CODERANGE_SET(dest, ENC_CODERANGE(src));
}


rb_str_conv_enc_opts(VALUE str, rb_encoding *from, rb_encoding *to, int ecflags, VALUE ecopts)
{
    rb_econv_t *ec;
    rb_econv_result_t ret;
    long len;
    VALUE newstr;
    const unsigned char *sp;
    unsigned char *dp;

    if (!to) return str;
    if (from == to) return str;
    if ((rb_enc_asciicompat(to) && ENC_CODERANGE(str) == ENC_CODERANGE_7BIT) ||
	to == rb_ascii8bit_encoding()) {
	if (STR_ENC_GET(str) != to) {
	    str = rb_str_dup(str);
	    rb_enc_associate(str, to);
	}
	return str;
    }

    len = RSTRING_LEN(str);
    newstr = rb_str_new(0, len);

  retry:
    ec = rb_econv_open_opts(from->name, to->name, ecflags, ecopts);
    if (!ec) return str;

    sp = (unsigned char*)RSTRING_PTR(str);
    dp = (unsigned char*)RSTRING_PTR(newstr);
    ret = rb_econv_convert(ec, &sp, (unsigned char*)RSTRING_END(str),
			   &dp, (unsigned char*)RSTRING_END(newstr), 0);
    rb_econv_close(ec);
    switch (ret) {
      case econv_destination_buffer_full:
	/* destination buffer short */
	len *= 2;
	rb_str_resize(newstr, len);
	goto retry;

      case econv_finished:
	len = dp - (unsigned char*)RSTRING_PTR(newstr);
	rb_str_set_len(newstr, len);
	rb_enc_associate(newstr, to);
	return newstr;

      default:
	/* some error, return original */
	return str;
    }
}


rb_str_dump(VALUE str)
{
    rb_encoding *enc = rb_enc_get(str);
    long len;
    const char *p, *pend;
    char *q, *qend;
    VALUE result;
    int u8 = (enc == rb_utf8_encoding());

    len = 2;			/* "" */
    p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
    while (p < pend) {
	unsigned char c = *p++;
	switch (c) {
	  case '"':  case '\\':
	  case '\n': case '\r':
	  case '\t': case '\f':
	  case '\013': case '\010': case '\007': case '\033':
	    len += 2;
	    break;

	  case '#':
	    len += IS_EVSTR(p, pend) ? 2 : 1;
	    break;

	  default:
	    if (ISPRINT(c)) {
		len++;
	    }
	    else {
		if (u8) {	/* \u{NN} */
		    char buf[32];
		    int n = rb_enc_precise_mbclen(p-1, pend, enc);
		    if (MBCLEN_CHARFOUND_P(n)) {
			int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
			sprintf(buf, "%x", cc);
			len += strlen(buf)+4;
			p += MBCLEN_CHARFOUND_LEN(n)-1;
			break;
		    }
		}
		len += 4;	/* \xNN */
	    }
	    break;
	}
    }
    if (!rb_enc_asciicompat(enc)) {
	len += 19;		/* ".force_encoding('')" */
	len += strlen(enc->name);
    }

    result = rb_str_new5(str, 0, len);
    p = RSTRING_PTR(str); pend = p + RSTRING_LEN(str);
    q = RSTRING_PTR(result); qend = q + len + 1;

    *q++ = '"';
    while (p < pend) {
	unsigned char c = *p++;

	if (c == '"' || c == '\\') {
	    *q++ = '\\';
	    *q++ = c;
	}
	else if (c == '#') {
	    if (IS_EVSTR(p, pend)) *q++ = '\\';
	    *q++ = '#';
	}
	else if (c == '\n') {
	    *q++ = '\\';
	    *q++ = 'n';
	}
	else if (c == '\r') {
	    *q++ = '\\';
	    *q++ = 'r';
	}
	else if (c == '\t') {
	    *q++ = '\\';
	    *q++ = 't';
	}
	else if (c == '\f') {
	    *q++ = '\\';
	    *q++ = 'f';
	}
	else if (c == '\013') {
	    *q++ = '\\';
	    *q++ = 'v';
	}
	else if (c == '\010') {
	    *q++ = '\\';
	    *q++ = 'b';
	}
	else if (c == '\007') {
	    *q++ = '\\';
	    *q++ = 'a';
	}
	else if (c == '\033') {
	    *q++ = '\\';
	    *q++ = 'e';
	}
	else if (ISPRINT(c)) {
	    *q++ = c;
	}
	else {
	    *q++ = '\\';
	    if (u8) {
		int n = rb_enc_precise_mbclen(p-1, pend, enc) - 1;
		if (MBCLEN_CHARFOUND_P(n)) {
		    int cc = rb_enc_mbc_to_codepoint(p-1, pend, enc);
		    p += n;
		    snprintf(q, qend-q, "u{%x}", cc);
		    q += strlen(q);
		    continue;
		}
	    }
	    snprintf(q, qend-q, "x%02X", c);
	    q += 3;
	}
    }
    *q++ = '"';
    *q = '\0';
    if (!rb_enc_asciicompat(enc)) {
	snprintf(q, qend-q, ".force_encoding(\"%s\")", enc->name);
	enc = rb_ascii8bit_encoding();
    }
    OBJ_INFECT(result, str);
    /* result from dump is ASCII */
    rb_enc_associate(result, enc);
    ENC_CODERANGE_SET(result, ENC_CODERANGE_7BIT);
    return result;
}


sym_inspect(VALUE sym)
{
    VALUE str;
    ID id = SYM2ID(sym);
    rb_encoding *enc;

    sym = rb_id2str(id);
    enc = STR_ENC_GET(sym);
    str = rb_enc_str_new(0, RSTRING_LEN(sym)+1, enc);
    RSTRING_PTR(str)[0] = ':';
    memcpy(RSTRING_PTR(str)+1, RSTRING_PTR(sym), RSTRING_LEN(sym));
    if (RSTRING_LEN(sym) != (long)strlen(RSTRING_PTR(sym)) ||
	!rb_enc_symname_p(RSTRING_PTR(sym), enc) ||
	!sym_printable(RSTRING_PTR(sym), RSTRING_END(sym), enc)) {
	str = rb_str_inspect(str);
	memcpy(RSTRING_PTR(str), ":\"", 2);
    }
    return str;
}


str_replace_shared(VALUE str2, VALUE str)
{
    if (RSTRING_LEN(str) <= RSTRING_EMBED_LEN_MAX) {
	STR_SET_EMBED(str2);
	memcpy(RSTRING_PTR(str2), RSTRING_PTR(str), RSTRING_LEN(str)+1);
	STR_SET_EMBED_LEN(str2, RSTRING_LEN(str));
    }
    else {
	FL_SET(str2, STR_NOEMBED);
	str = rb_str_new_frozen(str);
	RSTRING(str2)->as.heap.len = RSTRING_LEN(str);
	RSTRING(str2)->as.heap.ptr = RSTRING_PTR(str);
	RSTRING(str2)->as.heap.aux.shared = str;
	FL_SET(str2, ELTS_SHARED);
    }
    rb_enc_cr_str_exact_copy(str2, str);

    return str2;
}


rb_enc_cr_str_buf_cat(VALUE str, const char *ptr, long len,
    int ptr_encindex, int ptr_cr, int *ptr_cr_ret)
{
    int str_encindex = ENCODING_GET(str);
    int res_encindex;
    int str_cr, res_cr;
    int str_a8 = ENCODING_IS_ASCII8BIT(str);
    int ptr_a8 = ptr_encindex == 0;

    str_cr = ENC_CODERANGE(str);

    if (str_encindex == ptr_encindex) {
        if (str_cr == ENC_CODERANGE_UNKNOWN ||
            (ptr_a8 && str_cr != ENC_CODERANGE_7BIT)) {
            ptr_cr = ENC_CODERANGE_UNKNOWN;
        }
        else if (ptr_cr == ENC_CODERANGE_UNKNOWN) {
            ptr_cr = coderange_scan(ptr, len, rb_enc_from_index(ptr_encindex));
        }
    }
    else {
        rb_encoding *str_enc = rb_enc_from_index(str_encindex);
        rb_encoding *ptr_enc = rb_enc_from_index(ptr_encindex);
        if (!rb_enc_asciicompat(str_enc) || !rb_enc_asciicompat(ptr_enc)) {
            if (len == 0)
                return str;
            if (RSTRING_LEN(str) == 0) {
                rb_str_buf_cat(str, ptr, len);
                ENCODING_CODERANGE_SET(str, ptr_encindex, ptr_cr);
                return str;
            }
            goto incompatible;
        }
	if (ptr_cr == ENC_CODERANGE_UNKNOWN) {
	    ptr_cr = coderange_scan(ptr, len, ptr_enc);
	}
        if (str_cr == ENC_CODERANGE_UNKNOWN) {
            if (str_a8 || ptr_cr != ENC_CODERANGE_7BIT) {
                str_cr = rb_enc_str_coderange(str);
            }
        }
    }
    if (ptr_cr_ret)
        *ptr_cr_ret = ptr_cr;

    if (str_encindex != ptr_encindex &&
        str_cr != ENC_CODERANGE_7BIT &&
        ptr_cr != ENC_CODERANGE_7BIT) {
      incompatible:
        rb_raise(rb_eEncCompatError, "incompatible character encodings: %s and %s",
            rb_enc_name(rb_enc_from_index(str_encindex)),
            rb_enc_name(rb_enc_from_index(ptr_encindex)));
    }

    if (str_cr == ENC_CODERANGE_UNKNOWN) {
        res_encindex = str_encindex;
        res_cr = ENC_CODERANGE_UNKNOWN;
    }
    else if (str_cr == ENC_CODERANGE_7BIT) {
        if (ptr_cr == ENC_CODERANGE_7BIT) {
            res_encindex = !str_a8 ? str_encindex : ptr_encindex;
            res_cr = ENC_CODERANGE_7BIT;
        }
        else {
            res_encindex = ptr_encindex;
            res_cr = ptr_cr;
        }
    }
    else if (str_cr == ENC_CODERANGE_VALID) {
        res_encindex = str_encindex;
        res_cr = str_cr;
    }
    else { /* str_cr == ENC_CODERANGE_BROKEN */
        res_encindex = str_encindex;
        res_cr = str_cr;
        if (0 < len) res_cr = ENC_CODERANGE_UNKNOWN;
    }

    if (len < 0) {
	rb_raise(rb_eArgError, "negative string size (or size too big)");
    }
    str_buf_cat(str, ptr, len);
    ENCODING_CODERANGE_SET(str, res_encindex, res_cr);
    return str;
}


rb_str_aset_m(int argc, VALUE *argv, VALUE str)
{
    if (argc == 3) {
	if (TYPE(argv[0]) == T_REGEXP) {
	    rb_str_subpat_set(str, argv[0], argv[1], argv[2]);
	}
	else {
	    rb_str_splice(str, NUM2LONG(argv[0]), NUM2LONG(argv[1]), argv[2]);
	}
	return argv[2];
    }
    if (argc != 2) {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 2)", argc);
    }
    return rb_str_aset(str, argv[0], argv[1]);
}


rb_str_comparable(VALUE str1, VALUE str2)
{
    int idx1, idx2;
    int rc1, rc2;

    if (RSTRING_LEN(str1) == 0) return TRUE;
    if (RSTRING_LEN(str2) == 0) return TRUE;
    idx1 = ENCODING_GET(str1);
    idx2 = ENCODING_GET(str2);
    if (idx1 == idx2) return TRUE;
    rc1 = rb_enc_str_coderange(str1);
    rc2 = rb_enc_str_coderange(str2);
    if (rc1 == ENC_CODERANGE_7BIT) {
	if (rc2 == ENC_CODERANGE_7BIT) return TRUE;
	if (rb_enc_asciicompat(rb_enc_from_index(idx2)))
	    return TRUE;
    }
    if (rc2 == ENC_CODERANGE_7BIT) {
	if (rb_enc_asciicompat(rb_enc_from_index(idx1)))
	    return TRUE;
    }
    return FALSE;
}


rb_str_length(VALUE str)
{
    long len;

    len = str_strlen(str, STR_ENC_GET(str));
    return LONG2NUM(len);
}


rb_str_modify(VALUE str)
{
    if (!str_independent(str))
	str_make_independent(str);
    ENC_CODERANGE_CLEAR(str);
}


rb_str_capitalize(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_capitalize_bang(str);
    return str;
}


single_byte_optimizable(VALUE str)
{
    rb_encoding *enc;

    /* Conservative.  It may be ENC_CODERANGE_UNKNOWN. */
    if (ENC_CODERANGE(str) == ENC_CODERANGE_7BIT)
        return 1;

    enc = STR_ENC_GET(str);
    if (rb_enc_mbmaxlen(enc) == 1)
        return 1;

    /* Conservative.  Possibly single byte.
     * "\xa1" in Shift_JIS for example. */
    return 0;
}


sym_downcase(VALUE sym)
{
    return rb_str_intern(rb_str_downcase(rb_id2str(SYM2ID(sym))));
}


rb_str_count(int argc, VALUE *argv, VALUE str)
{
    char table[256];
    rb_encoding *enc = 0;
    VALUE del = 0, nodel = 0;
    char *s, *send;
    int i;
    int ascompat;

    if (argc < 1) {
	rb_raise(rb_eArgError, "wrong number of arguments");
    }
    for (i=0; i<argc; i++) {
	VALUE tstr = argv[i];
	unsigned char c;

	StringValue(tstr);
	enc = rb_enc_check(str, tstr);
	if (argc == 1 && RSTRING_LEN(tstr) == 1 && rb_enc_asciicompat(enc) &&
	    (c = RSTRING_PTR(tstr)[0]) < 0x80 && !is_broken_string(str)) {
	    int n = 0;

	    s = RSTRING_PTR(str);
	    if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
	    send = RSTRING_END(str);
	    while (s < send) {
		if (*(unsigned char*)s++ == c) n++;
	    }
	    return INT2NUM(n);
	}
	tr_setup_table(tstr, table, i==0, &del, &nodel, enc);
    }

    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return INT2FIX(0);
    send = RSTRING_END(str);
    ascompat = rb_enc_asciicompat(enc);
    i = 0;
    while (s < send) {
	unsigned int c;
	int clen;

	if (ascompat && (c = *(unsigned char*)s) < 0x80) {
	    clen = 1;
	    if (table[c]) {
		i++;
	    }
	    s++;
	}
	else {
	    c = rb_enc_codepoint_len(s, send, &clen, enc);
	    if (tr_find(c, table, del, nodel)) {
		i++;
	    }
	    s += clen;
	}
    }

    return INT2NUM(i);
}


rb_tainted_str_new_cstr(const char *ptr)
{
    VALUE str = rb_str_new2(ptr);

    OBJ_TAINT(str);
    return str;
}


rb_str_swapcase_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *send;
    int modify = 0;
    int n;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    s = RSTRING_PTR(str); send = RSTRING_END(str);
    while (s < send) {
	unsigned int c = rb_enc_codepoint_len(s, send, &n, enc);

	if (rb_enc_isupper(c, enc)) {
	    /* assuming toupper returns codepoint with same size */
	    rb_enc_mbcput(rb_enc_tolower(c, enc), s, enc);
	    modify = 1;
	}
	else if (rb_enc_islower(c, enc)) {
	    /* assuming tolower returns codepoint with same size */
	    rb_enc_mbcput(rb_enc_toupper(c, enc), s, enc);
	    modify = 1;
	}
	s += n;
    }

    if (modify) return str;
    return Qnil;
}


rb_usascii_str_new(const char *ptr, long len)
{
    VALUE str = rb_str_new(ptr, len);
    ENCODING_CODERANGE_SET(str, rb_usascii_encindex(), ENC_CODERANGE_7BIT);
    return str;
}


str_modify_keep_cr(VALUE str)
{
    if (!str_independent(str))
	str_make_independent(str);
    if (ENC_CODERANGE(str) == ENC_CODERANGE_BROKEN)
	/* Force re-scan later */
	ENC_CODERANGE_CLEAR(str);
}


rb_str_each_line(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    VALUE rs;
    unsigned int newline;
    const char *p, *pend, *s, *ptr;
    long len, rslen;
    VALUE line;
    int n;
    VALUE orig = str;

    if (argc == 0) {
	rs = rb_rs;
    }
    else {
	rb_scan_args(argc, argv, "01", &rs);
    }
    RETURN_ENUMERATOR(str, argc, argv);
    if (NIL_P(rs)) {
	rb_yield(str);
	return orig;
    }
    str = rb_str_new4(str);
    ptr = p = s = RSTRING_PTR(str);
    pend = p + RSTRING_LEN(str);
    len = RSTRING_LEN(str);
    StringValue(rs);
    if (rs == rb_default_rs) {
	enc = rb_enc_get(str);
	while (p < pend) {
	    char *p0;

	    p = memchr(p, '\n', pend - p);
	    if (!p) break;
	    p0 = rb_enc_left_char_head(s, p, pend, enc);
	    if (!rb_enc_is_newline(p0, pend, enc)) {
		p++;
		continue;
	    }
	    p = p0 + rb_enc_mbclen(p0, pend, enc);
	    line = rb_str_new5(str, s, p - s);
	    OBJ_INFECT(line, str);
	    rb_enc_cr_str_copy_for_substr(line, str);
	    rb_yield(line);
	    str_mod_check(str, ptr, len);
	    s = p;
	}
	goto finish;
    }

    enc = rb_enc_check(str, rs);
    rslen = RSTRING_LEN(rs);
    if (rslen == 0) {
	newline = '\n';
    }
    else {
	newline = rb_enc_codepoint(RSTRING_PTR(rs), RSTRING_END(rs), enc);
    }

    while (p < pend) {
	unsigned int c = rb_enc_codepoint_len(p, pend, &n, enc);

      again:
	if (rslen == 0 && c == newline) {
	    p += n;
	    if (p < pend && (c = rb_enc_codepoint_len(p, pend, &n, enc)) != newline) {
		goto again;
	    }
	    while (p < pend && rb_enc_codepoint(p, pend, enc) == newline) {
		p += n;
	    }
	    p -= n;
	}
	if (c == newline &&
	    (rslen <= 1 || memcmp(RSTRING_PTR(rs), p, rslen) == 0)) {
	    line = rb_str_new5(str, s, p - s + (rslen ? rslen : n));
	    OBJ_INFECT(line, str);
	    rb_enc_cr_str_copy_for_substr(line, str);
	    rb_yield(line);
	    str_mod_check(str, ptr, len);
	    s = p + (rslen ? rslen : n);
	}
	p += n;
    }

  finish:
    if (s != pend) {
	line = rb_str_new5(str, s, pend - s);
	OBJ_INFECT(line, str);
	rb_enc_cr_str_copy_for_substr(line, str);
	rb_yield(line);
    }

    return orig;
}


sym_succ(VALUE sym)
{
    return rb_str_intern(rb_str_succ(rb_sym_to_s(sym)));
}


sym_empty(VALUE sym)
{
    return rb_str_empty(rb_id2str(SYM2ID(sym)));
}


rb_str_substr(VALUE str, long beg, long len)
{
    rb_encoding *enc = STR_ENC_GET(str);
    VALUE str2;
    char *p, *s = RSTRING_PTR(str), *e = s + RSTRING_LEN(str);

    if (len < 0) return Qnil;
    if (!RSTRING_LEN(str)) {
	len = 0;
    }
    if (single_byte_optimizable(str)) {
	if (beg > RSTRING_LEN(str)) return Qnil;
	if (beg < 0) {
	    beg += RSTRING_LEN(str);
	    if (beg < 0) return Qnil;
	}
	if (beg + len > RSTRING_LEN(str))
	    len = RSTRING_LEN(str) - beg;
	if (len <= 0) {
	    len = 0;
	    p = 0;
	}
	else
	    p = s + beg;
	goto sub;
    }
    if (beg < 0) {
	if (len > -beg) len = -beg;
	if (-beg * rb_enc_mbmaxlen(enc) < RSTRING_LEN(str) / 8) {
	    beg = -beg;
	    while (beg-- > len && (e = rb_enc_prev_char(s, e, e, enc)) != 0);
	    p = e;
	    if (!p) return Qnil;
	    while (len-- > 0 && (p = rb_enc_prev_char(s, p, e, enc)) != 0);
	    if (!p) return Qnil;
	    len = e - p;
	    goto sub;
	}
	else {
	    beg += str_strlen(str, enc);
	    if (beg < 0) return Qnil;
	}
    }
    else if (beg > 0 && beg > str_strlen(str, enc)) {
	return Qnil;
    }
    if (len == 0) {
	p = 0;
    }
#ifdef NONASCII_MASK
    else if (ENC_CODERANGE(str) == ENC_CODERANGE_VALID &&
        enc == rb_utf8_encoding()) {
        p = str_utf8_nth(s, e, beg);
        len = str_utf8_offset(p, e, len);
    }
#endif
    else if (rb_enc_mbmaxlen(enc) == rb_enc_mbminlen(enc)) {
	int char_sz = rb_enc_mbmaxlen(enc);

	p = s + beg * char_sz;
	if (p > e) {
	    p = e;
	    len = 0;
	}
        else if (len * char_sz > e - p)
            len = e - p;
        else
	    len *= char_sz;
    }
    else if ((p = str_nth(s, e, beg, enc, 0)) == e) {
	len = 0;
    }
    else {
	len = str_offset(p, e, len, enc, 0);
    }
  sub:
    if (len > RSTRING_EMBED_LEN_MAX && beg + len == RSTRING_LEN(str)) {
	str2 = rb_str_new4(str);
	str2 = str_new3(rb_obj_class(str2), str2);
	RSTRING(str2)->as.heap.ptr += RSTRING(str2)->as.heap.len - len;
	RSTRING(str2)->as.heap.len = len;
    }
    else {
	str2 = rb_str_new5(str, p, len);
	rb_enc_cr_str_copy_for_substr(str2, str);
	OBJ_INFECT(str2, str);
    }

    return str2;
}


rb_str_hex(VALUE str)
{
    rb_encoding *enc = rb_enc_get(str);

    if (!rb_enc_asciicompat(enc)) {
	rb_raise(rb_eEncCompatError, "ASCII incompatible encoding: %s", rb_enc_name(enc));
    }
    return rb_str_to_inum(str, 16, FALSE);
}


enc_succ_char(char *p, long len, rb_encoding *enc)
{
    long i;
    int l;
    while (1) {
        for (i = len-1; 0 <= i && (unsigned char)p[i] == 0xff; i--)
            p[i] = '\0';
        if (i < 0)
            return NEIGHBOR_WRAPPED;
        ++((unsigned char*)p)[i];
        l = rb_enc_precise_mbclen(p, p+len, enc);
        if (MBCLEN_CHARFOUND_P(l)) {
            l = MBCLEN_CHARFOUND_LEN(l);
            if (l == len) {
                return NEIGHBOR_FOUND;
            }
            else {
                memset(p+l, 0xff, len-l);
            }
        }
        if (MBCLEN_INVALID_P(l) && i < len-1) {
            long len2;
            int l2;
            for (len2 = len-1; 0 < len2; len2--) {
                l2 = rb_enc_precise_mbclen(p, p+len2, enc);
                if (!MBCLEN_INVALID_P(l2))
                    break;
            }
            memset(p+len2+1, 0xff, len-(len2+1));
        }
    }
}


rb_str_s_try_convert(VALUE dummy, VALUE str)
{
    return rb_check_string_type(str);
}


str_new(VALUE klass, const char *ptr, long len)
{
    VALUE str;

    if (len < 0) {
	rb_raise(rb_eArgError, "negative string size (or size too big)");
    }

    str = str_alloc(klass);
    if (len > RSTRING_EMBED_LEN_MAX) {
	RSTRING(str)->as.heap.aux.capa = len;
	RSTRING(str)->as.heap.ptr = ALLOC_N(char,len+1);
	STR_SET_NOEMBED(str);
    }
    else if (len == 0) {
	ENC_CODERANGE_SET(str, ENC_CODERANGE_7BIT);
    }
    if (ptr) {
	memcpy(RSTRING_PTR(str), ptr, len);
    }
    STR_SET_LEN(str, len);
    RSTRING_PTR(str)[len] = '\0';
    return str;
}


rb_str_resize(VALUE str, long len)
{
    long slen;

    if (len < 0) {
	rb_raise(rb_eArgError, "negative string size (or size too big)");
    }

    rb_str_modify(str);
    slen = RSTRING_LEN(str);
    if (len != slen) {
	if (STR_EMBED_P(str)) {
	    char *ptr;
	    if (len <= RSTRING_EMBED_LEN_MAX) {
		STR_SET_EMBED_LEN(str, len);
		RSTRING(str)->as.ary[len] = '\0';
		return str;
	    }
	    ptr = ALLOC_N(char,len+1);
	    MEMCPY(ptr, RSTRING(str)->as.ary, char, slen);
	    RSTRING(str)->as.heap.ptr = ptr;
	    STR_SET_NOEMBED(str);
	}
	else if (len <= RSTRING_EMBED_LEN_MAX) {
	    char *ptr = RSTRING(str)->as.heap.ptr;
	    STR_SET_EMBED(str);
	    if (slen > 0) MEMCPY(RSTRING(str)->as.ary, ptr, char, len);
	    RSTRING(str)->as.ary[len] = '\0';
	    STR_SET_EMBED_LEN(str, len);
	    xfree(ptr);
	    return str;
	}
	else if (slen < len || slen - len > 1024) {
	    REALLOC_N(RSTRING(str)->as.heap.ptr, char, len+1);
	}
	if (!STR_NOCAPA_P(str)) {
	    RSTRING(str)->as.heap.aux.capa = len;
	}
	RSTRING(str)->as.heap.len = len;
	RSTRING(str)->as.heap.ptr[len] = '\0';	/* sentinel */
    }
    return str;
}


rb_str_chomp(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    rb_str_chomp_bang(argc, argv, str);
    return str;
}


rb_str_casecmp(VALUE str1, VALUE str2)
{
    long len;
    rb_encoding *enc;
    char *p1, *p1end, *p2, *p2end;

    StringValue(str2);
    enc = rb_enc_compatible(str1, str2);
    if (!enc) {
	return Qnil;
    }

    p1 = RSTRING_PTR(str1); p1end = RSTRING_END(str1);
    p2 = RSTRING_PTR(str2); p2end = RSTRING_END(str2);
    if (single_byte_optimizable(str1) && single_byte_optimizable(str2)) {
	while (p1 < p1end && p2 < p2end) {
	    if (*p1 != *p2) {
		unsigned int c1 = TOUPPER(*p1 & 0xff);
		unsigned int c2 = TOUPPER(*p2 & 0xff);
                if (c1 != c2)
                    return INT2FIX(c1 < c2 ? -1 : 1);
	    }
	    p1++;
	    p2++;
	}
    }
    else {
	while (p1 < p1end && p2 < p2end) {
            int l1, c1 = rb_enc_ascget(p1, p1end, &l1, enc);
            int l2, c2 = rb_enc_ascget(p2, p2end, &l2, enc);

            if (0 <= c1 && 0 <= c2) {
                c1 = TOUPPER(c1);
                c2 = TOUPPER(c2);
                if (c1 != c2)
                    return INT2FIX(c1 < c2 ? -1 : 1);
            }
            else {
                int r;
                l1 = rb_enc_mbclen(p1, p1end, enc);
                l2 = rb_enc_mbclen(p2, p2end, enc);
                len = l1 < l2 ? l1 : l2;
                r = memcmp(p1, p2, len);
                if (r != 0)
                    return INT2FIX(r < 0 ? -1 : 1);
                if (l1 != l2)
                    return INT2FIX(l1 < l2 ? -1 : 1);
            }
	    p1 += l1;
	    p2 += l2;
	}
    }
    if (RSTRING_LEN(str1) == RSTRING_LEN(str2)) return INT2FIX(0);
    if (RSTRING_LEN(str1) > RSTRING_LEN(str2)) return INT2FIX(1);
    return INT2FIX(-1);
}


rb_str_set_len(VALUE str, long len)
{
    STR_SET_LEN(str, len);
    RSTRING_PTR(str)[len] = '\0';
}


rb_str_reverse_bang(VALUE str)
{
    if (RSTRING_LEN(str) > 1) {
	if (single_byte_optimizable(str)) {
	    char *s, *e, c;

	    str_modify_keep_cr(str);
	    s = RSTRING_PTR(str);
	    e = RSTRING_END(str) - 1;
	    while (s < e) {
		c = *s;
		*s++ = *e;
		*e-- = c;
	    }
	}
	else {
	    rb_str_shared_replace(str, rb_str_reverse(str));
	}
    }
    else {
	str_modify_keep_cr(str);
    }
    return str;
}


str_make_independent(VALUE str)
{
    char *ptr;
    long len = RSTRING_LEN(str);

    ptr = ALLOC_N(char, len+1);
    if (RSTRING_PTR(str)) {
	memcpy(ptr, RSTRING_PTR(str), len);
    }
    STR_SET_NOEMBED(str);
    ptr[len] = 0;
    RSTRING(str)->as.heap.ptr = ptr;
    RSTRING(str)->as.heap.len = len;
    RSTRING(str)->as.heap.aux.capa = len;
    STR_UNSET_NOCAPA(str);
}


tr_find(unsigned int c, char table[256], VALUE del, VALUE nodel)
{
    if (c < 256) {
	return table[c] != 0;
    }
    else {
	VALUE v = UINT2NUM(c);

	if (del && !NIL_P(rb_hash_lookup(del, v))) {
	    if (!nodel || NIL_P(rb_hash_lookup(nodel, v))) {
		return TRUE;
	    }
	}
	return FALSE;
    }
}


rb_str_tmp_new(long len)
{
    return str_new(0, 0, len);
}


rb_str_chomp_bang(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    VALUE rs;
    int newline;
    char *p, *pp, *e;
    long len, rslen;

    str_modify_keep_cr(str);
    len = RSTRING_LEN(str);
    if (len == 0) return Qnil;
    p = RSTRING_PTR(str);
    e = p + len;
    if (argc == 0) {
	rs = rb_rs;
	if (rs == rb_default_rs) {
	  smart_chomp:
	    enc = rb_enc_get(str);
	    if (rb_enc_mbminlen(enc) > 1) {
		pp = rb_enc_left_char_head(p, e-rb_enc_mbminlen(enc), e, enc);
		if (rb_enc_is_newline(pp, e, enc)) {
		    e = pp;
		}
		pp = e - rb_enc_mbminlen(enc);
		if (pp >= p) {
		    pp = rb_enc_left_char_head(p, pp, e, enc);
		    if (rb_enc_ascget(pp, e, 0, enc) == '\r') {
			e = pp;
		    }
		}
		if (e == RSTRING_END(str)) {
		    return Qnil;
		}
		len = e - RSTRING_PTR(str);
		STR_SET_LEN(str, len);
	    }
	    else {
		if (RSTRING_PTR(str)[len-1] == '\n') {
		    STR_DEC_LEN(str);
		    if (RSTRING_LEN(str) > 0 &&
			RSTRING_PTR(str)[RSTRING_LEN(str)-1] == '\r') {
			STR_DEC_LEN(str);
		    }
		}
		else if (RSTRING_PTR(str)[len-1] == '\r') {
		    STR_DEC_LEN(str);
		}
		else {
		    return Qnil;
		}
	    }
	    RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
	    return str;
	}
    }
    else {
	rb_scan_args(argc, argv, "01", &rs);
    }
    if (NIL_P(rs)) return Qnil;
    StringValue(rs);
    rslen = RSTRING_LEN(rs);
    if (rslen == 0) {
	while (len>0 && p[len-1] == '\n') {
	    len--;
	    if (len>0 && p[len-1] == '\r')
		len--;
	}
	if (len < RSTRING_LEN(str)) {
	    STR_SET_LEN(str, len);
	    RSTRING_PTR(str)[len] = '\0';
	    return str;
	}
	return Qnil;
    }
    if (rslen > len) return Qnil;
    newline = RSTRING_PTR(rs)[rslen-1];
    if (rslen == 1 && newline == '\n')
	goto smart_chomp;

    enc = rb_enc_check(str, rs);
    if (is_broken_string(rs)) {
	return Qnil;
    }
    pp = e - rslen;
    if (p[len-1] == newline &&
	(rslen <= 1 ||
	 memcmp(RSTRING_PTR(rs), pp, rslen) == 0)) {
	if (rb_enc_left_char_head(p, pp, e, enc) != pp)
	    return Qnil;
	if (ENC_CODERANGE(str) != ENC_CODERANGE_7BIT) {
	    ENC_CODERANGE_CLEAR(str);
	}
	STR_SET_LEN(str, RSTRING_LEN(str) - rslen);
	RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
	return str;
    }
    return Qnil;
}


rb_str_rstrip_bang(VALUE str)
{
    rb_encoding *enc;
    char *s, *t, *e;

    str_modify_keep_cr(str);
    enc = STR_ENC_GET(str);
    rb_str_check_dummy_enc(enc);
    s = RSTRING_PTR(str);
    if (!s || RSTRING_LEN(str) == 0) return Qnil;
    t = e = RSTRING_END(str);

    /* remove trailing spaces or '\0's */
    if (single_byte_optimizable(str)) {
	unsigned char c;
	while (s < t && ((c = *(t-1)) == '\0' || ascii_isspace(c))) t--;
    }
    else {
	char *tp;

        while ((tp = rb_enc_prev_char(s, t, e, enc)) != NULL) {
	    unsigned int c = rb_enc_codepoint(tp, e, enc);
	    if (c && !rb_isspace(c)) break;
	    t = tp;
	}
    }
    if (t < e) {
	long len = t-RSTRING_PTR(str);

	STR_SET_LEN(str, len);
	RSTRING_PTR(str)[len] = '\0';
	return str;
    }
    return Qnil;
}


rb_str_ord(VALUE s)
{
    unsigned int c;

    c = rb_enc_codepoint(RSTRING_PTR(s), RSTRING_END(s), STR_ENC_GET(s));
    return UINT2NUM(c);
}


rb_str_tr_bang(VALUE str, VALUE src, VALUE repl)
{
    return tr_trans(str, src, repl, 0);
}


str_new4(VALUE klass, VALUE str)
{
    VALUE str2;

    str2 = str_alloc(klass);
    STR_SET_NOEMBED(str2);
    RSTRING(str2)->as.heap.len = RSTRING_LEN(str);
    RSTRING(str2)->as.heap.ptr = RSTRING_PTR(str);
    if (STR_SHARED_P(str)) {
	VALUE shared = RSTRING(str)->as.heap.aux.shared;
	assert(OBJ_FROZEN(shared));
	FL_SET(str2, ELTS_SHARED);
	RSTRING(str2)->as.heap.aux.shared = shared;
    }
    else {
	FL_SET(str, ELTS_SHARED);
	RSTRING(str)->as.heap.aux.shared = str2;
    }
    rb_enc_cr_str_exact_copy(str2, str);
    OBJ_INFECT(str2, str);
    return str2;
}


rb_str_partition(VALUE str, VALUE sep)
{
    long pos;
    int regex = FALSE;

    if (TYPE(sep) == T_REGEXP) {
	pos = rb_reg_search(sep, str, 0, 0);
	regex = TRUE;
    }
    else {
	VALUE tmp;

	tmp = rb_check_string_type(sep);
	if (NIL_P(tmp)) {
	    rb_raise(rb_eTypeError, "type mismatch: %s given",
		     rb_obj_classname(sep));
	}
	sep = tmp;
	pos = rb_str_index(str, sep, 0);
    }
    if (pos < 0) {
      failed:
	return rb_ary_new3(3, str, rb_str_new(0,0),rb_str_new(0,0));
    }
    if (regex) {
	sep = rb_str_subpat(str, sep, INT2FIX(0));
	if (pos == 0 && RSTRING_LEN(sep) == 0) goto failed;
    }
    return rb_ary_new3(3, rb_str_subseq(str, 0, pos),
		          sep,
		          rb_str_subseq(str, pos+RSTRING_LEN(sep),
					     RSTRING_LEN(str)-pos-RSTRING_LEN(sep)));
}


str_cat_char(VALUE str, unsigned int c, rb_encoding *enc)
{
    char s[RUBY_MAX_CHAR_LEN];
    int n = rb_enc_codelen(c, enc);

    rb_enc_mbcput(c, s, enc);
    rb_enc_str_buf_cat(str, s, n, enc);
}


rb_str_subseq(VALUE str, long beg, long len)
{
    VALUE str2;

    if (RSTRING_LEN(str) == beg + len &&
        RSTRING_EMBED_LEN_MAX < len) {
        str2 = rb_str_new_shared(rb_str_new_frozen(str));
        rb_str_drop_bytes(str2, beg);
    }
    else {
        str2 = rb_str_new5(str, RSTRING_PTR(str)+beg, len);
    }

    rb_enc_cr_str_copy_for_substr(str2, str);
    OBJ_INFECT(str2, str);

    return str2;
}


rb_str_equal(VALUE str1, VALUE str2)
{
    if (str1 == str2) return Qtrue;
    if (TYPE(str2) != T_STRING) {
	if (!rb_respond_to(str2, rb_intern("to_str"))) {
	    return Qfalse;
	}
	return rb_equal(str2, str1);
    }
    return str_eql(str1, str2);
}


chopped_length(VALUE str)
{
    rb_encoding *enc = STR_ENC_GET(str);
    const char *p, *p2, *beg, *end;

    beg = RSTRING_PTR(str);
    end = beg + RSTRING_LEN(str);
    if (beg > end) return 0;
    p = rb_enc_prev_char(beg, end, end, enc);
    if (!p) return 0;
    if (p > beg && rb_enc_ascget(p, end, 0, enc) == '\n') {
	p2 = rb_enc_prev_char(beg, p, end, enc);
	if (p2 && rb_enc_ascget(p2, end, 0, enc) == '\r') p = p2;
    }
    return p - beg;
}


rb_str_new_shared(VALUE str)
{
    VALUE str2 = str_new3(rb_obj_class(str), str);

    OBJ_INFECT(str2, str);
    return str2;
}


rb_str_succ(VALUE orig)
{
    rb_encoding *enc;
    VALUE str;
    char *sbeg, *s, *e, *last_alnum = 0;
    int c = -1;
    long l;
    char carry[ONIGENC_CODE_TO_MBC_MAXLEN] = "\1";
    long carry_pos = 0, carry_len = 1;
    enum neighbor_char neighbor = NEIGHBOR_FOUND;

    str = rb_str_new5(orig, RSTRING_PTR(orig), RSTRING_LEN(orig));
    rb_enc_cr_str_copy_for_substr(str, orig);
    OBJ_INFECT(str, orig);
    if (RSTRING_LEN(str) == 0) return str;

    enc = STR_ENC_GET(orig);
    sbeg = RSTRING_PTR(str);
    s = e = sbeg + RSTRING_LEN(str);

    while ((s = rb_enc_prev_char(sbeg, s, e, enc)) != 0) {
	if (neighbor == NEIGHBOR_NOT_CHAR && last_alnum) {
	    if (ISALPHA(*last_alnum) ? ISDIGIT(*s) :
		ISDIGIT(*last_alnum) ? ISALPHA(*s) : 0) {
		s = last_alnum;
		break;
	    }
	}
	if ((l = rb_enc_precise_mbclen(s, e, enc)) <= 0) continue;
        neighbor = enc_succ_alnum_char(s, l, enc, carry);
        switch (neighbor) {
	  case NEIGHBOR_NOT_CHAR:
	    continue;
	  case NEIGHBOR_FOUND:
	    return str;
	  case NEIGHBOR_WRAPPED:
	    last_alnum = s;
	    break;
	}
        c = 1;
        carry_pos = s - sbeg;
        carry_len = l;
    }
    if (c == -1) {		/* str contains no alnum */
	s = e;
	while ((s = rb_enc_prev_char(sbeg, s, e, enc)) != 0) {
            enum neighbor_char neighbor;
            if ((l = rb_enc_precise_mbclen(s, e, enc)) <= 0) continue;
            neighbor = enc_succ_char(s, l, enc);
            if (neighbor == NEIGHBOR_FOUND)
                return str;
            if (rb_enc_precise_mbclen(s, s+l, enc) != l) {
                /* wrapped to \0...\0.  search next valid char. */
                enc_succ_char(s, l, enc);
            }
            if (!rb_enc_asciicompat(enc)) {
                MEMCPY(carry, s, char, l);
                carry_len = l;
            }
            carry_pos = s - sbeg;
	}
    }
    RESIZE_CAPA(str, RSTRING_LEN(str) + carry_len);
    s = RSTRING_PTR(str) + carry_pos;
    memmove(s + carry_len, s, RSTRING_LEN(str) - carry_pos);
    memmove(s, carry, carry_len);
    STR_SET_LEN(str, RSTRING_LEN(str) + carry_len);
    RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
    rb_enc_str_coderange(str);
    return str;
}


rb_str_locktmp(VALUE str)
{
    if (FL_TEST(str, STR_TMPLOCK)) {
	rb_raise(rb_eRuntimeError, "temporal locking already locked string");
    }
    FL_SET(str, STR_TMPLOCK);
    return str;
}


rb_str_strip(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_strip_bang(str);
    return str;
}


rb_str_offset(VALUE str, long pos)
{
    return str_offset(RSTRING_PTR(str), RSTRING_END(str), pos,
		      STR_ENC_GET(str), single_byte_optimizable(str));
}


str_eql(const VALUE str1, const VALUE str2)
{
    const long len = RSTRING_LEN(str1);

    if (len != RSTRING_LEN(str2)) return Qfalse;
    if (!rb_str_comparable(str1, str2)) return Qfalse;
    if (memcmp(RSTRING_PTR(str1), RSTRING_PTR(str2), len) == 0)
	return Qtrue;
    return Qfalse;
}


rb_str_gsub_bang(int argc, VALUE *argv, VALUE str)
{
    str_modify_keep_cr(str);
    return str_gsub(argc, argv, str, 1);
}


rb_locale_str_new_cstr(const char *ptr)
{
    return rb_external_str_new_with_enc(ptr, strlen(ptr), rb_locale_encoding());
}


rb_str_free(VALUE str)
{
    if (!STR_EMBED_P(str) && !STR_SHARED_P(str)) {
	xfree(RSTRING(str)->as.heap.ptr);
    }
}


rb_str_include(VALUE str, VALUE arg)
{
    long i;

    StringValue(arg);
    i = rb_str_index(str, arg, 0);

    if (i == -1) return Qfalse;
    return Qtrue;
}


str_strlen(VALUE str, rb_encoding *enc)
{
    const char *p, *e;
    long n;
    int cr;

    if (single_byte_optimizable(str)) return RSTRING_LEN(str);
    if (!enc) enc = STR_ENC_GET(str);
    p = RSTRING_PTR(str);
    e = RSTRING_END(str);
    cr = ENC_CODERANGE(str);
#ifdef NONASCII_MASK
    if (ENC_CODERANGE(str) == ENC_CODERANGE_VALID &&
        enc == rb_utf8_encoding()) {

	VALUE len = 0;
	if ((int)sizeof(VALUE) * 2 < e - p) {
	    const VALUE *s, *t;
	    const VALUE lowbits = sizeof(VALUE) - 1;
	    s = (const VALUE*)(~lowbits & ((VALUE)p + lowbits));
	    t = (const VALUE*)(~lowbits & (VALUE)e);
	    while (p < (const char *)s) {
		if (is_utf8_lead_byte(*p)) len++;
		p++;
	    }
	    while (s < t) {
		len += count_utf8_lead_bytes_with_word(s);
		s++;
	    }
	    p = (const char *)s;
	}
	while (p < e) {
	    if (is_utf8_lead_byte(*p)) len++;
	    p++;
	}
	return (long)len;
    }
#endif
    n = rb_enc_strlen_cr(p, e, enc, &cr);
    if (cr) {
        ENC_CODERANGE_SET(str, cr);
    }
    return n;
}


rb_string_value_ptr(volatile VALUE *ptr)
{
    VALUE str = rb_string_value(ptr);
    return RSTRING_PTR(str);
}


rb_str_dup(VALUE str)
{
    return str_duplicate(rb_obj_class(str), str);
}


rb_enc_cr_str_copy_for_substr(VALUE dest, VALUE src)
{
    /* this function is designed for copying encoding and coderange
     * from src to new string "dest" which is made from the part of src.
     */
    str_enc_copy(dest, src);
    switch (ENC_CODERANGE(src)) {
      case ENC_CODERANGE_7BIT:
	ENC_CODERANGE_SET(dest, ENC_CODERANGE_7BIT);
	break;
      case ENC_CODERANGE_VALID:
	if (!rb_enc_asciicompat(STR_ENC_GET(src)) ||
	    search_nonascii(RSTRING_PTR(dest), RSTRING_END(dest)))
	    ENC_CODERANGE_SET(dest, ENC_CODERANGE_VALID);
	else
	    ENC_CODERANGE_SET(dest, ENC_CODERANGE_7BIT);
	break;
      default:
	if (RSTRING_LEN(dest) == 0) {
	    if (!rb_enc_asciicompat(STR_ENC_GET(src)))
		ENC_CODERANGE_SET(dest, ENC_CODERANGE_VALID);
	    else
		ENC_CODERANGE_SET(dest, ENC_CODERANGE_7BIT);
	}
	break;
    }
}


rb_str_cat2(VALUE str, const char *ptr)
{
    return rb_str_cat(str, ptr, strlen(ptr));
}


rb_tainted_str_new(const char *ptr, long len)
{
    VALUE str = rb_str_new(ptr, len);

    OBJ_TAINT(str);
    return str;
}


rb_str_swapcase(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_swapcase_bang(str);
    return str;
}


rb_str_delete(int argc, VALUE *argv, VALUE str)
{
    str = rb_str_dup(str);
    rb_str_delete_bang(argc, argv, str);
    return str;
}


sym_equal(VALUE sym1, VALUE sym2)
{
    if (sym1 == sym2) return Qtrue;
    return Qfalse;
}


rb_external_str_new_cstr(const char *ptr)
{
    return rb_external_str_new_with_enc(ptr, strlen(ptr), rb_default_external_encoding());
}


rb_external_str_new(const char *ptr, long len)
{
    return rb_external_str_new_with_enc(ptr, len, rb_default_external_encoding());
}


rb_str_is_ascii_only_p(VALUE str)
{
    int cr = rb_enc_str_coderange(str);

    return cr == ENC_CODERANGE_7BIT ? Qtrue : Qfalse;
}


rb_str_split_m(int argc, VALUE *argv, VALUE str)
{
    rb_encoding *enc;
    VALUE spat;
    VALUE limit;
    enum {awk, string, regexp} split_type;
    long beg, end, i = 0;
    int lim = 0;
    VALUE result, tmp;

    if (rb_scan_args(argc, argv, "02", &spat, &limit) == 2) {
	lim = NUM2INT(limit);
	if (lim <= 0) limit = Qnil;
	else if (lim == 1) {
	    if (RSTRING_LEN(str) == 0)
		return rb_ary_new2(0);
	    return rb_ary_new3(1, str);
	}
	i = 1;
    }

    enc = STR_ENC_GET(str);
    if (NIL_P(spat)) {
	if (!NIL_P(rb_fs)) {
	    spat = rb_fs;
	    goto fs_set;
	}
	split_type = awk;
    }
    else {
      fs_set:
	if (TYPE(spat) == T_STRING) {
	    rb_encoding *enc2 = STR_ENC_GET(spat);

	    split_type = string;
	    if (RSTRING_LEN(spat) == 0) {
		/* Special case - split into chars */
		spat = rb_reg_regcomp(spat);
		split_type = regexp;
	    }
	    else if (rb_enc_asciicompat(enc2) == 1) {
		if (RSTRING_LEN(spat) == 1 && RSTRING_PTR(spat)[0] == ' '){
		    split_type = awk;
		}
	    }
	    else {
		int l;
		if (rb_enc_ascget(RSTRING_PTR(spat), RSTRING_END(spat), &l, enc2) == ' ' &&
		    RSTRING_LEN(spat) == l) {
		    split_type = awk;
		}
	    }
	}
	else {
	    spat = get_pat(spat, 1);
	    split_type = regexp;
	}
    }

    result = rb_ary_new();
    beg = 0;
    if (split_type == awk) {
	char *ptr = RSTRING_PTR(str);
	char *eptr = RSTRING_END(str);
	char *bptr = ptr;
	int skip = 1;
	unsigned int c;

	end = beg;
	if (is_ascii_string(str)) {
	    while (ptr < eptr) {
		c = (unsigned char)*ptr++;
		if (skip) {
		    if (ascii_isspace(c)) {
			beg = ptr - bptr;
		    }
		    else {
			end = ptr - bptr;
			skip = 0;
			if (!NIL_P(limit) && lim <= i) break;
		    }
		}
		else if (ascii_isspace(c)) {
		    rb_ary_push(result, rb_str_subseq(str, beg, end-beg));
		    skip = 1;
		    beg = ptr - bptr;
		    if (!NIL_P(limit)) ++i;
		}
		else {
		    end = ptr - bptr;
		}
	    }
	}
	else {
	    while (ptr < eptr) {
		int n;

		c = rb_enc_codepoint_len(ptr, eptr, &n, enc);
		ptr += n;
		if (skip) {
		    if (rb_isspace(c)) {
			beg = ptr - bptr;
		    }
		    else {
			end = ptr - bptr;
			skip = 0;
			if (!NIL_P(limit) && lim <= i) break;
		    }
		}
		else if (rb_isspace(c)) {
		    rb_ary_push(result, rb_str_subseq(str, beg, end-beg));
		    skip = 1;
		    beg = ptr - bptr;
		    if (!NIL_P(limit)) ++i;
		}
		else {
		    end = ptr - bptr;
		}
	    }
	}
    }
    else if (split_type == string) {
	char *ptr = RSTRING_PTR(str);
	char *temp = ptr;
	char *eptr = RSTRING_END(str);
	char *sptr = RSTRING_PTR(spat);
	long slen = RSTRING_LEN(spat);

	if (is_broken_string(str)) {
	    rb_raise(rb_eArgError, "invalid byte sequence in %s", rb_enc_name(STR_ENC_GET(str)));
	}
	if (is_broken_string(spat)) {
	    rb_raise(rb_eArgError, "invalid byte sequence in %s", rb_enc_name(STR_ENC_GET(spat)));
	}
	enc = rb_enc_check(str, spat);
	while (ptr < eptr &&
	       (end = rb_memsearch(sptr, slen, ptr, eptr - ptr, enc)) >= 0) {
	    /* Check we are at the start of a char */
	    char *t = rb_enc_right_char_head(ptr, ptr + end, eptr, enc);
	    if (t != ptr + end) {
		ptr = t;
		continue;
	    }
	    rb_ary_push(result, rb_str_subseq(str, ptr - temp, end));
	    ptr += end + slen;
	    if (!NIL_P(limit) && lim <= ++i) break;
	}
	beg = ptr - temp;
    }
    else {
	char *ptr = RSTRING_PTR(str);
	long len = RSTRING_LEN(str);
	long start = beg;
	long idx;
	int last_null = 0;
	struct re_registers *regs;

	while ((end = rb_reg_search(spat, str, start, 0)) >= 0) {
	    regs = RMATCH_REGS(rb_backref_get());
	    if (start == end && BEG(0) == END(0)) {
		if (!ptr) {
		    rb_ary_push(result, rb_str_new("", 0));
		    break;
		}
		else if (last_null == 1) {
		    rb_ary_push(result, rb_str_subseq(str, beg,
						      rb_enc_fast_mbclen(ptr+beg,
									 ptr+len,
									 enc)));
		    beg = start;
		}
		else {
                    if (ptr+start == ptr+len)
                        start++;
                    else
                        start += rb_enc_fast_mbclen(ptr+start,ptr+len,enc);
		    last_null = 1;
		    continue;
		}
	    }
	    else {
		rb_ary_push(result, rb_str_subseq(str, beg, end-beg));
		beg = start = END(0);
	    }
	    last_null = 0;

	    for (idx=1; idx < regs->num_regs; idx++) {
		if (BEG(idx) == -1) continue;
		if (BEG(idx) == END(idx))
		    tmp = rb_str_new5(str, 0, 0);
		else
		    tmp = rb_str_subseq(str, BEG(idx), END(idx)-BEG(idx));
		rb_ary_push(result, tmp);
	    }
	    if (!NIL_P(limit) && lim <= ++i) break;
	}
    }
    if (RSTRING_LEN(str) > 0 && (!NIL_P(limit) || RSTRING_LEN(str) > beg || lim < 0)) {
	if (RSTRING_LEN(str) == beg)
	    tmp = rb_str_new5(str, 0, 0);
	else
	    tmp = rb_str_subseq(str, beg, RSTRING_LEN(str)-beg);
	rb_ary_push(result, tmp);
    }
    if (NIL_P(limit) && lim == 0) {
	long len;
	while ((len = RARRAY_LEN(result)) > 0 &&
	       (tmp = RARRAY_PTR(result)[len-1], RSTRING_LEN(tmp) == 0))
	    rb_ary_pop(result);
    }

    return result;
}


str_frozen_check(VALUE s)
{
    if (OBJ_FROZEN(s)) {
	rb_raise(rb_eRuntimeError, "string frozen");
    }
}


rb_str_gsub(int argc, VALUE *argv, VALUE str)
{
    return str_gsub(argc, argv, str, 0);
}


str_gsub(int argc, VALUE *argv, VALUE str, int bang)
{
    VALUE pat, val, repl, match, dest, hash = Qnil;
    struct re_registers *regs;
    long beg, n;
    long beg0, end0;
    long offset, blen, slen, len, last;
    int iter = 0;
    char *sp, *cp;
    int tainted = 0;
    rb_encoding *str_enc;

    switch (argc) {
      case 1:
	RETURN_ENUMERATOR(str, argc, argv);
	iter = 1;
	break;
      case 2:
	repl = argv[1];
	hash = rb_check_convert_type(argv[1], T_HASH, "Hash", "to_hash");
	if (NIL_P(hash)) {
	    StringValue(repl);
	}
	if (OBJ_TAINTED(repl)) tainted = 1;
	break;
      default:
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 2)", argc);
    }

    pat = get_pat(argv[0], 1);
    beg = rb_reg_search(pat, str, 0, 0);
    if (beg < 0) {
	if (bang) return Qnil;	/* no match, no substitution */
	return rb_str_dup(str);
    }

    offset = 0;
    n = 0;
    blen = RSTRING_LEN(str) + 30; /* len + margin */
    dest = rb_str_buf_new(blen);
    sp = RSTRING_PTR(str);
    slen = RSTRING_LEN(str);
    cp = sp;
    str_enc = STR_ENC_GET(str);

    do {
	n++;
	match = rb_backref_get();
	regs = RMATCH_REGS(match);
	beg0 = BEG(0);
	end0 = END(0);
	if (iter || !NIL_P(hash)) {
            if (iter) {
                val = rb_obj_as_string(rb_yield(rb_reg_nth_match(0, match)));
            }
            else {
                val = rb_hash_aref(hash, rb_str_subseq(str, BEG(0), END(0) - BEG(0)));
                val = rb_obj_as_string(val);
            }
	    str_mod_check(str, sp, slen);
	    if (val == dest) { 	/* paranoid check [ruby-dev:24827] */
		rb_raise(rb_eRuntimeError, "block should not cheat");
	    }
	}
	else {
	    val = rb_reg_regsub(repl, str, regs, pat);
	}

	if (OBJ_TAINTED(val)) tainted = 1;

	len = beg - offset;	/* copy pre-match substr */
        if (len) {
            rb_enc_str_buf_cat(dest, cp, len, str_enc);
        }

        rb_str_buf_append(dest, val);

	last = offset;
	offset = end0;
	if (beg0 == end0) {
	    /*
	     * Always consume at least one character of the input string
	     * in order to prevent infinite loops.
	     */
	    if (RSTRING_LEN(str) <= end0) break;
	    len = rb_enc_fast_mbclen(RSTRING_PTR(str)+end0, RSTRING_END(str), str_enc);
            rb_enc_str_buf_cat(dest, RSTRING_PTR(str)+end0, len, str_enc);
	    offset = end0 + len;
	}
	cp = RSTRING_PTR(str) + offset;
	if (offset > RSTRING_LEN(str)) break;
	beg = rb_reg_search(pat, str, offset, 0);
    } while (beg >= 0);
    if (RSTRING_LEN(str) > offset) {
        rb_enc_str_buf_cat(dest, cp, RSTRING_LEN(str) - offset, str_enc);
    }
    rb_reg_search(pat, str, last, 0);
    if (bang) {
        rb_str_shared_replace(str, dest);
    }
    else {
	RBASIC(dest)->klass = rb_obj_class(str);
	OBJ_INFECT(dest, str);
	str = dest;
    }

    if (tainted) OBJ_TAINT(str);
    return str;
}


sym_length(VALUE sym)
{
    return rb_str_length(rb_id2str(SYM2ID(sym)));
}


rb_str_center(int argc, VALUE *argv, VALUE str)
{
    return rb_str_justify(argc, argv, str, 'c');
}


scan_once(VALUE str, VALUE pat, long *start)
{
    VALUE result, match;
    struct re_registers *regs;
    int i;

    if (rb_reg_search(pat, str, *start, 0) >= 0) {
	match = rb_backref_get();
	regs = RMATCH_REGS(match);
	if (BEG(0) == END(0)) {
	    rb_encoding *enc = STR_ENC_GET(str);
	    /*
	     * Always consume at least one character of the input string
	     */
	    if (RSTRING_LEN(str) > END(0))
		*start = END(0)+rb_enc_fast_mbclen(RSTRING_PTR(str)+END(0),
						   RSTRING_END(str), enc);
	    else
		*start = END(0)+1;
	}
	else {
	    *start = END(0);
	}
	if (regs->num_regs == 1) {
	    return rb_reg_nth_match(0, match);
	}
	result = rb_ary_new2(regs->num_regs);
	for (i=1; i < regs->num_regs; i++) {
	    rb_ary_push(result, rb_reg_nth_match(i, match));
	}

	return result;
    }
    return Qnil;
}


coderange_scan(const char *p, long len, rb_encoding *enc)
{
    const char *e = p + len;

    if (rb_enc_to_index(enc) == 0) {
        /* enc is ASCII-8BIT.  ASCII-8BIT string never be broken. */
        p = search_nonascii(p, e);
        return p ? ENC_CODERANGE_VALID : ENC_CODERANGE_7BIT;
    }

    if (rb_enc_asciicompat(enc)) {
        p = search_nonascii(p, e);
        if (!p) {
            return ENC_CODERANGE_7BIT;
        }
        while (p < e) {
            int ret = rb_enc_precise_mbclen(p, e, enc);
            if (!MBCLEN_CHARFOUND_P(ret)) {
                return ENC_CODERANGE_BROKEN;
            }
            p += MBCLEN_CHARFOUND_LEN(ret);
            if (p < e) {
                p = search_nonascii(p, e);
                if (!p) {
                    return ENC_CODERANGE_VALID;
                }
            }
        }
        if (e < p) {
            return ENC_CODERANGE_BROKEN;
        }
        return ENC_CODERANGE_VALID;
    }

    while (p < e) {
        int ret = rb_enc_precise_mbclen(p, e, enc);

        if (!MBCLEN_CHARFOUND_P(ret)) {
            return ENC_CODERANGE_BROKEN;
        }
        p += MBCLEN_CHARFOUND_LEN(ret);
    }
    if (e < p) {
        return ENC_CODERANGE_BROKEN;
    }
    return ENC_CODERANGE_VALID;
}


rb_str_splice_0(VALUE str, long beg, long len, VALUE val)
{
    if (beg == 0 && RSTRING_LEN(val) == 0) {
	rb_str_drop_bytes(str, len);
	OBJ_INFECT(str, val);
	return;
    }

    rb_str_modify(str);
    if (len < RSTRING_LEN(val)) {
	/* expand string */
	RESIZE_CAPA(str, RSTRING_LEN(str) + RSTRING_LEN(val) - len + 1);
    }

    if (RSTRING_LEN(val) != len) {
	memmove(RSTRING_PTR(str) + beg + RSTRING_LEN(val),
		RSTRING_PTR(str) + beg + len,
		RSTRING_LEN(str) - (beg + len));
    }
    if (RSTRING_LEN(val) < beg && len < 0) {
	MEMZERO(RSTRING_PTR(str) + RSTRING_LEN(str), char, -len);
    }
    if (RSTRING_LEN(val) > 0) {
	memmove(RSTRING_PTR(str)+beg, RSTRING_PTR(val), RSTRING_LEN(val));
    }
    STR_SET_LEN(str, RSTRING_LEN(str) + RSTRING_LEN(val) - len);
    if (RSTRING_PTR(str)) {
	RSTRING_PTR(str)[RSTRING_LEN(str)] = '\0';
    }
    OBJ_INFECT(str, val);
}


rb_str_subpat(VALUE str, VALUE re, VALUE backref)
{
    if (rb_reg_search(re, str, 0, 0) >= 0) {
        VALUE match = rb_backref_get();
        int nth = rb_reg_backref_number(match, backref);
	return rb_reg_nth_match(nth, match);
    }
    return Qnil;
}


rb_str_getbyte(VALUE str, VALUE index)
{
    long pos = NUM2LONG(index);

    if (pos < 0)
        pos += RSTRING_LEN(str);
    if (pos < 0 ||  RSTRING_LEN(str) <= pos)
        return Qnil;

    return INT2FIX((unsigned char)RSTRING_PTR(str)[pos]);
}


str_modifiable(VALUE str)
{
    if (FL_TEST(str, STR_TMPLOCK)) {
	rb_raise(rb_eRuntimeError, "can't modify string; temporarily locked");
    }
    if (OBJ_FROZEN(str)) rb_error_frozen("string");
    if (!OBJ_UNTRUSTED(str) && rb_safe_level() >= 4)
	rb_raise(rb_eSecurityError, "Insecure: can't modify string");
}


rb_str_lstrip(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_lstrip_bang(str);
    return str;
}


rb_str_buf_cat2(VALUE str, const char *ptr)
{
    return rb_str_buf_cat(str, ptr, strlen(ptr));
}


rb_str_export_to_enc(VALUE str, rb_encoding *enc)
{
    return rb_str_conv_enc(str, STR_ENC_GET(str), enc);
}


rb_str_export_locale(VALUE str)
{
    return rb_str_conv_enc(str, STR_ENC_GET(str), rb_locale_encoding());
}


rb_str_to_s(VALUE str)
{
    if (rb_obj_class(str) != rb_cString) {
	return str_duplicate(rb_cString, str);
    }
    return str;
}


rb_enc_strlen(const char *p, const char *e, rb_encoding *enc)
{
    return enc_strlen(p, e, enc, ENC_CODERANGE_UNKNOWN);
}


rb_str_times(VALUE str, VALUE times)
{
    VALUE str2;
    long n, len;
    char *ptr2;

    len = NUM2LONG(times);
    if (len < 0) {
	rb_raise(rb_eArgError, "negative argument");
    }
    if (len && LONG_MAX/len <  RSTRING_LEN(str)) {
	rb_raise(rb_eArgError, "argument too big");
    }

    str2 = rb_str_new5(str, 0, len *= RSTRING_LEN(str));
    ptr2 = RSTRING_PTR(str2);
    if (len) {
        n = RSTRING_LEN(str);
        memcpy(ptr2, RSTRING_PTR(str), n);
        while (n <= len/2) {
            memcpy(ptr2 + n, ptr2, n);
            n *= 2;
        }
        memcpy(ptr2 + n, ptr2, len-n);
    }
    ptr2[RSTRING_LEN(str2)] = '\0';
    OBJ_INFECT(str2, str);
    rb_enc_cr_str_copy_for_substr(str2, str);

    return str2;
}


rb_str_succ_bang(VALUE str)
{
    rb_str_shared_replace(str, rb_str_succ(str));

    return str;
}


rb_str_aref(VALUE str, VALUE indx)
{
    long idx;

    switch (TYPE(indx)) {
      case T_FIXNUM:
	idx = FIX2LONG(indx);

      num_index:
	str = rb_str_substr(str, idx, 1);
	if (!NIL_P(str) && RSTRING_LEN(str) == 0) return Qnil;
	return str;

      case T_REGEXP:
	return rb_str_subpat(str, indx, INT2FIX(0));

      case T_STRING:
	if (rb_str_index(str, indx, 0) != -1)
	    return rb_str_dup(indx);
	return Qnil;

      default:
	/* check if indx is Range */
	{
	    long beg, len;
	    VALUE tmp;

	    len = str_strlen(str, STR_ENC_GET(str));
	    switch (rb_range_beg_len(indx, &beg, &len, len, 0)) {
	      case Qfalse:
		break;
	      case Qnil:
		return Qnil;
	      default:
		tmp = rb_str_substr(str, beg, len);
		return tmp;
	    }
	}
	idx = NUM2LONG(indx);
	goto num_index;
    }
    return Qnil;		/* not reached */
}


str_nth(const char *p, const char *e, long nth, rb_encoding *enc, int singlebyte)
{
    if (singlebyte)
	p += nth;
    else {
	p = rb_enc_nth(p, e, nth, enc);
    }
    if (!p) return 0;
    if (p > e) p = e;
    return (char *)p;
}


rb_str_chop(VALUE str)
{
    VALUE str2 = rb_str_new5(str, RSTRING_PTR(str), chopped_length(str));
    rb_enc_cr_str_copy_for_substr(str2, str);
    OBJ_INFECT(str2, str);
    return str2;
}


rb_str_chr(VALUE str)
{
    return rb_str_substr(str, 0, 1);
}


rb_str_buf_new_cstr(const char *ptr)
{
    VALUE str;
    long len = strlen(ptr);

    str = rb_str_buf_new(len);
    rb_str_buf_cat(str, ptr, len);

    return str;
}


sym_to_proc(VALUE sym)
{
    static VALUE sym_proc_cache = Qfalse;
    enum {SYM_PROC_CACHE_SIZE = 67};
    VALUE proc;
    long id, index;
    VALUE *aryp;

    if (!sym_proc_cache) {
	sym_proc_cache = rb_ary_tmp_new(SYM_PROC_CACHE_SIZE * 2);
	rb_gc_register_mark_object(sym_proc_cache);
	rb_ary_store(sym_proc_cache, SYM_PROC_CACHE_SIZE*2 - 1, Qnil);
    }

    id = SYM2ID(sym);
    index = (id % SYM_PROC_CACHE_SIZE) << 1;

    aryp = RARRAY_PTR(sym_proc_cache);
    if (aryp[index] == sym) {
	return aryp[index + 1];
    }
    else {
	proc = rb_proc_new(sym_call, (VALUE)id);
	aryp[index] = sym;
	aryp[index + 1] = proc;
	return proc;
    }
}


rb_str_sub_bang(int argc, VALUE *argv, VALUE str)
{
    VALUE pat, repl, hash = Qnil;
    int iter = 0;
    int tainted = 0;
    int untrusted = 0;
    long plen;

    if (argc == 1 && rb_block_given_p()) {
	iter = 1;
    }
    else if (argc == 2) {
	repl = argv[1];
	hash = rb_check_convert_type(argv[1], T_HASH, "Hash", "to_hash");
	if (NIL_P(hash)) {
	    StringValue(repl);
	}
	if (OBJ_TAINTED(repl)) tainted = 1;
	if (OBJ_UNTRUSTED(repl)) untrusted = 1;
    }
    else {
	rb_raise(rb_eArgError, "wrong number of arguments (%d for 2)", argc);
    }

    pat = get_pat(argv[0], 1);
    if (rb_reg_search(pat, str, 0, 0) >= 0) {
	rb_encoding *enc;
	int cr = ENC_CODERANGE(str);
	VALUE match = rb_backref_get();
	struct re_registers *regs = RMATCH_REGS(match);
	long beg0 = BEG(0);
	long end0 = END(0);
	char *p, *rp;
	long len, rlen;

	if (iter || !NIL_P(hash)) {
	    p = RSTRING_PTR(str); len = RSTRING_LEN(str);

            if (iter) {
                repl = rb_obj_as_string(rb_yield(rb_reg_nth_match(0, match)));
            }
            else {
                repl = rb_hash_aref(hash, rb_str_subseq(str, beg0, end0 - beg0));
                repl = rb_obj_as_string(repl);
            }
	    str_mod_check(str, p, len);
	    str_frozen_check(str);
	}
	else {
	    repl = rb_reg_regsub(repl, str, regs, pat);
	}
        enc = rb_enc_compatible(str, repl);
        if (!enc) {
            rb_encoding *str_enc = STR_ENC_GET(str);
	    p = RSTRING_PTR(str); len = RSTRING_LEN(str);
	    if (coderange_scan(p, beg0, str_enc) != ENC_CODERANGE_7BIT ||
		coderange_scan(p+end0, len-end0, str_enc) != ENC_CODERANGE_7BIT) {
                rb_raise(rb_eEncCompatError, "incompatible character encodings: %s and %s",
			 rb_enc_name(str_enc),
			 rb_enc_name(STR_ENC_GET(repl)));
            }
            enc = STR_ENC_GET(repl);
        }
	rb_str_modify(str);
	rb_enc_associate(str, enc);
	if (OBJ_TAINTED(repl)) tainted = 1;
	if (OBJ_UNTRUSTED(repl)) untrusted = 1;
	if (ENC_CODERANGE_UNKNOWN < cr && cr < ENC_CODERANGE_BROKEN) {
	    int cr2 = ENC_CODERANGE(repl);
            if (cr2 == ENC_CODERANGE_BROKEN ||
                (cr == ENC_CODERANGE_VALID && cr2 == ENC_CODERANGE_7BIT))
                cr = ENC_CODERANGE_UNKNOWN;
            else
                cr = cr2;
	}
	plen = end0 - beg0;
	rp = RSTRING_PTR(repl); rlen = RSTRING_LEN(repl);
	len = RSTRING_LEN(str);
	if (rlen > plen) {
	    RESIZE_CAPA(str, len + rlen - plen);
	}
	p = RSTRING_PTR(str);
	if (rlen != plen) {
	    memmove(p + beg0 + rlen, p + beg0 + plen, len - beg0 - plen);
	}
	memcpy(p + beg0, rp, rlen);
	len += rlen - plen;
	STR_SET_LEN(str, len);
	RSTRING_PTR(str)[len] = '\0';
	ENC_CODERANGE_SET(str, cr);
	if (tainted) OBJ_TAINT(str);
	if (untrusted) OBJ_UNTRUST(str);

	return str;
    }
    return Qnil;
}


rb_str_new_frozen(VALUE orig)
{
    VALUE klass, str;

    if (OBJ_FROZEN(orig)) return orig;
    klass = rb_obj_class(orig);
    if (STR_SHARED_P(orig) && (str = RSTRING(orig)->as.heap.aux.shared)) {
	long ofs;
	assert(OBJ_FROZEN(str));
	ofs = RSTRING_LEN(str) - RSTRING_LEN(orig);
	if ((ofs > 0) || (klass != RBASIC(str)->klass) ||
	    (!OBJ_TAINTED(str) && OBJ_TAINTED(orig)) ||
	    ENCODING_GET(str) != ENCODING_GET(orig)) {
	    str = str_new3(klass, str);
	    RSTRING(str)->as.heap.ptr += ofs;
	    RSTRING(str)->as.heap.len -= ofs;
	    rb_enc_cr_str_exact_copy(str, orig);
	    OBJ_INFECT(str, orig);
	}
    }
    else if (STR_EMBED_P(orig)) {
	str = str_new(klass, RSTRING_PTR(orig), RSTRING_LEN(orig));
	rb_enc_cr_str_exact_copy(str, orig);
	OBJ_INFECT(str, orig);
    }
    else if (STR_ASSOC_P(orig)) {
	VALUE assoc = RSTRING(orig)->as.heap.aux.shared;
	FL_UNSET(orig, STR_ASSOC);
	str = str_new4(klass, orig);
	FL_SET(str, STR_ASSOC);
	RSTRING(str)->as.heap.aux.shared = assoc;
    }
    else {
	str = str_new4(klass, orig);
    }
    OBJ_FREEZE(str);
    return str;
}


rb_str_split(VALUE str, const char *sep0)
{
    VALUE sep;

    StringValue(str);
    sep = rb_str_new2(sep0);
    return rb_str_split_m(1, &sep, str);
}


rb_str_concat(VALUE str1, VALUE str2)
{
    if (FIXNUM_P(str2) || TYPE(str2) == T_BIGNUM) {
	rb_encoding *enc = STR_ENC_GET(str1);
	unsigned int c = NUM2UINT(str2);
	long pos = RSTRING_LEN(str1);
	int len = rb_enc_codelen(c, enc);
	int cr = ENC_CODERANGE(str1);

	rb_str_resize(str1, pos+len);
	rb_enc_mbcput(c, RSTRING_PTR(str1)+pos, enc);
	ENC_CODERANGE_SET(str1, cr);
	return str1;
    }
    return rb_str_append(str1, str2);
}


rb_str_start_with(int argc, VALUE *argv, VALUE str)
{
    int i;

    for (i=0; i<argc; i++) {
	VALUE tmp = rb_check_string_type(argv[i]);
	if (NIL_P(tmp)) continue;
	rb_enc_check(str, tmp);
	if (RSTRING_LEN(str) < RSTRING_LEN(tmp)) continue;
	if (memcmp(RSTRING_PTR(str), RSTRING_PTR(tmp), RSTRING_LEN(tmp)) == 0)
	    return Qtrue;
    }
    return Qfalse;
}


rb_enc_str_asciionly_p(VALUE str)
{
    rb_encoding *enc = STR_ENC_GET(str);

    if (!rb_enc_asciicompat(enc))
        return FALSE;
    else if (rb_enc_str_coderange(str) == ENC_CODERANGE_7BIT)
        return TRUE;
    return FALSE;
}


rb_str_export(VALUE str)
{
    return rb_str_conv_enc(str, STR_ENC_GET(str), rb_default_external_encoding());
}


rb_obj_as_string(VALUE obj)
{
    VALUE str;

    if (TYPE(obj) == T_STRING) {
	return obj;
    }
    str = rb_funcall(obj, id_to_s, 0);
    if (TYPE(str) != T_STRING)
	return rb_any_to_s(obj);
    if (OBJ_TAINTED(obj)) OBJ_TAINT(str);
    return str;
}


rb_str_justify(int argc, VALUE *argv, VALUE str, char jflag)
{
    rb_encoding *enc;
    VALUE w;
    long width, len, flen = 1, fclen = 1;
    VALUE res;
    char *p;
    const char *f = " ";
    long n, size, llen, rlen, llen2 = 0, rlen2 = 0;
    volatile VALUE pad;
    int singlebyte = 1, cr;

    rb_scan_args(argc, argv, "11", &w, &pad);
    enc = STR_ENC_GET(str);
    width = NUM2LONG(w);
    if (argc == 2) {
	StringValue(pad);
	enc = rb_enc_check(str, pad);
	f = RSTRING_PTR(pad);
	flen = RSTRING_LEN(pad);
	fclen = str_strlen(pad, enc);
	singlebyte = single_byte_optimizable(pad);
	if (flen == 0 || fclen == 0) {
	    rb_raise(rb_eArgError, "zero width padding");
	}
    }
    len = str_strlen(str, enc);
    if (width < 0 || len >= width) return rb_str_dup(str);
    n = width - len;
    llen = (jflag == 'l') ? 0 : ((jflag == 'r') ? n : n/2);
    rlen = n - llen;
    cr = ENC_CODERANGE(str);
    if (flen > 1) {
       llen2 = str_offset(f, f + flen, llen % fclen, enc, singlebyte);
       rlen2 = str_offset(f, f + flen, rlen % fclen, enc, singlebyte);
    }
    size = RSTRING_LEN(str);
    if ((len = llen / fclen + rlen / fclen) >= LONG_MAX / flen ||
       (len *= flen) >= LONG_MAX - llen2 - rlen2 ||
       (len += llen2 + rlen2) >= LONG_MAX - size) {
       rb_raise(rb_eArgError, "argument too big");
    }
    len += size;
    res = rb_str_new5(str, 0, len);
    p = RSTRING_PTR(res);
    if (flen <= 1) {
       memset(p, *f, llen);
       p += llen;
    }
    else {
       while (llen > fclen) {
	    memcpy(p,f,flen);
	    p += flen;
	    llen -= fclen;
	}
       if (llen > 0) {
           memcpy(p, f, llen2);
           p += llen2;
	}
    }
    memcpy(p, RSTRING_PTR(str), size);
    p += size;
    if (flen <= 1) {
       memset(p, *f, rlen);
       p += rlen;
    }
    else {
       while (rlen > fclen) {
	    memcpy(p,f,flen);
	    p += flen;
	    rlen -= fclen;
	}
       if (rlen > 0) {
           memcpy(p, f, rlen2);
           p += rlen2;
	}
    }
    *p = '\0';
    STR_SET_LEN(res, p-RSTRING_PTR(res));
    OBJ_INFECT(res, str);
    if (!NIL_P(pad)) OBJ_INFECT(res, pad);
    rb_enc_associate(res, enc);
    if (argc == 2)
	cr = ENC_CODERANGE_AND(cr, ENC_CODERANGE(pad));
    if (cr != ENC_CODERANGE_BROKEN)
	ENC_CODERANGE_SET(res, cr);
    return res;
}


rb_str_each_byte(VALUE str)
{
    long i;

    RETURN_ENUMERATOR(str, 0, 0);
    for (i=0; i<RSTRING_LEN(str); i++) {
	rb_yield(INT2FIX(RSTRING_PTR(str)[i] & 0xff));
    }
    return str;
}


rb_str_capacity(VALUE str)
{
    if (STR_EMBED_P(str)) {
	return RSTRING_EMBED_LEN_MAX;
    }
    else if (STR_NOCAPA_P(str)) {
	return RSTRING(str)->as.heap.len;
    }
    else {
	return RSTRING(str)->as.heap.aux.capa;
    }
}


enc_pred_char(char *p, long len, rb_encoding *enc)
{
    long i;
    int l;
    while (1) {
        for (i = len-1; 0 <= i && (unsigned char)p[i] == 0; i--)
            p[i] = '\xff';
        if (i < 0)
            return NEIGHBOR_WRAPPED;
        --((unsigned char*)p)[i];
        l = rb_enc_precise_mbclen(p, p+len, enc);
        if (MBCLEN_CHARFOUND_P(l)) {
            l = MBCLEN_CHARFOUND_LEN(l);
            if (l == len) {
                return NEIGHBOR_FOUND;
            }
            else {
                memset(p+l, 0, len-l);
            }
        }
        if (MBCLEN_INVALID_P(l) && i < len-1) {
            long len2;
            int l2;
            for (len2 = len-1; 0 < len2; len2--) {
                l2 = rb_enc_precise_mbclen(p, p+len2, enc);
                if (!MBCLEN_INVALID_P(l2))
                    break;
            }
            memset(p+len2+1, 0, len-(len2+1));
        }
    }
}


sym_casecmp(VALUE sym, VALUE other)
{
    if (!SYMBOL_P(other)) {
	return Qnil;
    }
    return rb_str_casecmp(rb_sym_to_s(sym), rb_sym_to_s(other));
}


rb_str_associated(VALUE str)
{
    if (STR_SHARED_P(str)) str = RSTRING(str)->as.heap.aux.shared;
    if (STR_ASSOC_P(str)) {
	return RSTRING(str)->as.heap.aux.shared;
    }
    return Qfalse;
}


rb_str_buf_append(VALUE str, VALUE str2)
{
    int str2_cr;

    str2_cr = ENC_CODERANGE(str2);

    rb_enc_cr_str_buf_cat(str, RSTRING_PTR(str2), RSTRING_LEN(str2),
        ENCODING_GET(str2), str2_cr, &str2_cr);

    OBJ_INFECT(str, str2);
    ENC_CODERANGE_SET(str2, str2_cr);

    return str;
}


rb_str_cmp(VALUE str1, VALUE str2)
{
    long len;
    int retval;

    len = lesser(RSTRING_LEN(str1), RSTRING_LEN(str2));
    retval = memcmp(RSTRING_PTR(str1), RSTRING_PTR(str2), len);
    if (retval == 0) {
	if (RSTRING_LEN(str1) == RSTRING_LEN(str2)) {
	    if (!rb_str_comparable(str1, str2)) {
		if (ENCODING_GET(str1) > ENCODING_GET(str2))
		    return 1;
		return -1;
	    }
	    return 0;
	}
	if (RSTRING_LEN(str1) > RSTRING_LEN(str2)) return 1;
	return -1;
    }
    if (retval > 0) return 1;
    return -1;
}


sym_call(VALUE args, VALUE sym, int argc, VALUE *argv)
{
    VALUE obj;

    if (argc < 1) {
	rb_raise(rb_eArgError, "no receiver given");
    }
    obj = argv[0];
    return rb_funcall3(obj, (ID)sym, argc - 1, argv + 1);
}


rb_enc_str_coderange(VALUE str)
{
    int cr = ENC_CODERANGE(str);

    if (cr == ENC_CODERANGE_UNKNOWN) {
	rb_encoding *enc = STR_ENC_GET(str);
        cr = coderange_scan(RSTRING_PTR(str), RSTRING_LEN(str), enc);
        ENC_CODERANGE_SET(str, cr);
    }
    return cr;
}


str_independent(VALUE str)
{
    str_modifiable(str);
    if (!STR_SHARED_P(str)) return 1;
    if (STR_EMBED_P(str)) return 1;
    return 0;
}


str_buf_cat(VALUE str, const char *ptr, long len)
{
    long capa, total, off = -1;

    if (ptr >= RSTRING_PTR(str) && ptr <= RSTRING_END(str)) {
        off = ptr - RSTRING_PTR(str);
    }
    rb_str_modify(str);
    if (len == 0) return 0;
    if (STR_ASSOC_P(str)) {
	FL_UNSET(str, STR_ASSOC);
	capa = RSTRING(str)->as.heap.aux.capa = RSTRING_LEN(str);
    }
    else if (STR_EMBED_P(str)) {
	capa = RSTRING_EMBED_LEN_MAX;
    }
    else {
	capa = RSTRING(str)->as.heap.aux.capa;
    }
    if (RSTRING_LEN(str) >= LONG_MAX - len) {
	rb_raise(rb_eArgError, "string sizes too big");
    }
    total = RSTRING_LEN(str)+len;
    if (capa <= total) {
	while (total > capa) {
	    if (capa + 1 >= LONG_MAX / 2) {
		capa = (total + 4095) / 4096;
		break;
	    }
	    capa = (capa + 1) * 2;
	}
	RESIZE_CAPA(str, capa);
    }
    if (off != -1) {
        ptr = RSTRING_PTR(str) + off;
    }
    memcpy(RSTRING_PTR(str) + RSTRING_LEN(str), ptr, len);
    STR_SET_LEN(str, total);
    RSTRING_PTR(str)[total] = '\0'; /* sentinel */

    return str;
}


rb_str_downcase(VALUE str)
{
    str = rb_str_dup(str);
    rb_str_downcase_bang(str);
    return str;
}