+ao_poly
+ao_scheme_do_string_ref(struct ao_scheme_cons *cons)
+{
+ char *string;
+ int32_t ref;
+ if (!ao_scheme_check_argc(_ao_scheme_atom_string2dref, cons, 2, 2))
+ return AO_SCHEME_NIL;
+ if (!ao_scheme_check_argt(_ao_scheme_atom_string2dref, cons, 0, AO_SCHEME_STRING, 0))
+ return AO_SCHEME_NIL;
+ ref = ao_scheme_arg_int(_ao_scheme_atom_string2dref, cons, 1);
+ if (ref == AO_SCHEME_NOT_INTEGER)
+ return AO_SCHEME_NIL;
+ string = ao_scheme_poly_string(ao_scheme_arg(cons, 0));
+ while (*string && ref) {
+ ++string;
+ --ref;
+ }
+ if (!*string)
+ return ao_scheme_error(AO_SCHEME_INVALID, "%v: string %v ref %v invalid",
+ _ao_scheme_atom_string2dref,
+ ao_scheme_arg(cons, 0),
+ ao_scheme_arg(cons, 1));
+ return ao_scheme_int_poly(*string);
+}
+
+ao_poly
+ao_scheme_do_string_length(struct ao_scheme_cons *cons)
+{
+ char *string;
+
+ if (!ao_scheme_check_argc(_ao_scheme_atom_string2dlength, cons, 1, 1))
+ return AO_SCHEME_NIL;
+ if (!ao_scheme_check_argt(_ao_scheme_atom_string2dlength, cons, 0, AO_SCHEME_STRING, 0))
+ return AO_SCHEME_NIL;
+ string = ao_scheme_poly_string(ao_scheme_arg(cons, 0));
+ return ao_scheme_integer_poly(strlen(string));
+}
+
+ao_poly
+ao_scheme_do_string_copy(struct ao_scheme_cons *cons)
+{
+ char *string;
+
+ if (!ao_scheme_check_argc(_ao_scheme_atom_string2dcopy, cons, 1, 1))
+ return AO_SCHEME_NIL;
+ if (!ao_scheme_check_argt(_ao_scheme_atom_string2dcopy, cons, 0, AO_SCHEME_STRING, 0))
+ return AO_SCHEME_NIL;
+ string = ao_scheme_poly_string(ao_scheme_arg(cons, 0));
+ return ao_scheme_string_poly(ao_scheme_string_copy(string));
+}
+
+ao_poly
+ao_scheme_do_string_set(struct ao_scheme_cons *cons)
+{
+ char *string;
+ int32_t ref;
+ int32_t val;
+
+ if (!ao_scheme_check_argc(_ao_scheme_atom_string2dset21, cons, 3, 3))
+ return AO_SCHEME_NIL;
+ if (!ao_scheme_check_argt(_ao_scheme_atom_string2dset21, cons, 0, AO_SCHEME_STRING, 0))
+ return AO_SCHEME_NIL;
+ string = ao_scheme_poly_string(ao_scheme_arg(cons, 0));
+ ref = ao_scheme_arg_int(_ao_scheme_atom_string2dset21, cons, 1);
+ if (ref == AO_SCHEME_NOT_INTEGER)
+ return AO_SCHEME_NIL;
+ val = ao_scheme_arg_int(_ao_scheme_atom_string2dset21, cons, 2);
+ if (val == AO_SCHEME_NOT_INTEGER)
+ return AO_SCHEME_NIL;
+ while (*string && ref) {
+ ++string;
+ --ref;
+ }
+ if (!*string)
+ return ao_scheme_error(AO_SCHEME_INVALID, "%v: string %v ref %v invalid",
+ _ao_scheme_atom_string2dset21,
+ ao_scheme_arg(cons, 0),
+ ao_scheme_arg(cons, 1));
+ *string = val;
+ return ao_scheme_int_poly(*string);
+}
+