int test_environment()
{
symbol *sa = new_symbol("a");
symbol *sb = new_symbol("b");
symbol *sc = new_symbol("c");
symbol *sx = new_symbol("x");
symbol *sy = new_symbol("y");
symbol *sz = new_symbol("z");
symbol *sn = new_symbol("n");
integer *i10 = new_integer(10);
integer *i20 = new_integer(20);
integer *i30 = new_integer(30);
integer *i40 = new_integer(40);
integer *i50 = new_integer(50);
integer *i60 = new_integer(60);
list *vara = cons(sa, cons(sb, cons(sc, NULL)));
list *varx = cons(sx, cons(sy, cons(sz, NULL)));
list *val10 = cons(i10, cons(i20, cons(i30, NULL)));
list *val40 = cons(i40, cons(i50, cons(i60, NULL)));
environment *env = NULL;
env = extend_env(vara, val10, env);
assert(generic_equal(lookup_var_val(sa, env), cons(sa, i10)));
assert(generic_equal(lookup_var_val(sb, env), cons(sb, i20)));
assert(generic_equal(lookup_var_val(sc, env), cons(sc, i30)));
env = define_var_val(sx, i40, env);
assert(generic_equal(lookup_var_val(sa, env), cons(sa, i10)));
assert(generic_equal(lookup_var_val(sb, env), cons(sb, i20)));
assert(generic_equal(lookup_var_val(sc, env), cons(sc, i30)));
assert(generic_equal(lookup_var_val(sx, env), cons(sx, i40)));
assert(generic_equal(lookup_var_val(sy, env), NULL));
env = set_var_val(sx, i50, env);
assert(generic_equal(lookup_var_val(sa, env), cons(sa, i10)));
assert(generic_equal(lookup_var_val(sb, env), cons(sb, i20)));
assert(generic_equal(lookup_var_val(sc, env), cons(sc, i30)));
assert(generic_equal(lookup_var_val(sx, env), cons(sx, i50)));
assert(generic_equal(lookup_var_val(sy, env), NULL));
env = extend_env(varx, val40, env);
assert(generic_equal(lookup_var_val(sa, env), cons(sa, i10)));
assert(generic_equal(lookup_var_val(sb, env), cons(sb, i20)));
assert(generic_equal(lookup_var_val(sc, env), cons(sc, i30)));
assert(generic_equal(lookup_var_val(sx, env), cons(sx, i40)));
assert(generic_equal(lookup_var_val(sy, env), cons(sy, i50)));
assert(generic_equal(lookup_var_val(sz, env), cons(sz, i60)));
assert(generic_equal(lookup_var_val(sn, env), NULL));
return 1;
}
//one arg: exp
static cellpoint eval_assignment(void)
{
//calls assignment_variable
args_push(args_ref(1));
reg = assignment_variable();
stack_push(&vars_stack, reg);
//compute assignment value
args_push(args_ref(1));
reg = assignment_value();
args_push(a_false);
args_push(reg);
reg = eval();
stack_push(&vars_stack, reg);
//calls set_var_val
args_push(current_env);
args_push(stack_pop(&vars_stack));
args_push(stack_pop(&vars_stack));
set_var_val();
args_pop(1);
return make_symbol("ok");
}