squeeze!

static VALUE
rb_str_squeeze_bang(int argc, VALUE *argv, VALUE str)
{
 char squeez[TR_TABLE_SIZE];
 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;
 }
 }
 }
 TERM_FILL(t, TERM_LEN(str));
 if (t - RSTRING_PTR(str) != RSTRING_LEN(str)) {
 STR_SET_LEN(str, t - RSTRING_PTR(str));
 modify = 1;
 }
 if (modify) return str;
 return Qnil;
}