remove IsClause

src/prolog/machine/machine_state.rs

@@ -324,7 +324,7 @@ pub(crate) trait CallPolicy: Any {
         let b = machine_st.b - 1;
         let n = machine_st.or_stack[b].num_args();
 
-        for i in 1 .. n + 1 {            
+        for i in 1 .. n + 1 {
             machine_st.registers[i] = machine_st.or_stack[b][i].clone();
         }
 
@@ -510,11 +510,11 @@ pub(crate) trait CallPolicy: Any {
 
                 return_from_clause!(machine_st.last_call, machine_st)
             },
-            &BuiltInClauseType::Is => {
-                let a = machine_st[temp_v!(1)].clone();
-                let result = machine_st.arith_eval_by_metacall(temp_v!(2))?;
+            &BuiltInClauseType::Is(r, ref at) => {
+                let a1 = machine_st[r].clone();
+                let a2 = machine_st.get_number(at)?;
 
-                machine_st.unify(a, Addr::Con(Constant::Number(result)));
+                machine_st.unify(a1, Addr::Con(Constant::Number(a2)));
                 return_from_clause!(machine_st.last_call, machine_st)
             },
         }

src/prolog/machine/machine_state_impl.rs

@@ -323,7 +323,7 @@ impl MachineState {
         };
     }
 
-    fn get_number(&self, at: &ArithmeticTerm) -> Result<Number, MachineError> {
+    pub(super) fn get_number(&self, at: &ArithmeticTerm) -> Result<Number, MachineError> {
         match at {
             &ArithmeticTerm::Reg(r)        => self.arith_eval_by_metacall(r),
             &ArithmeticTerm::Interm(i)     => Ok(self.interms[i-1].clone()),
@@ -1879,15 +1879,6 @@ impl MachineState {
 
                 self.fail = true;
             },
-            &ControlInstruction::IsClause(lco, r, ref at) => {
-                self.last_call = lco;
-
-                let a1 = self[r].clone();
-                let a2 = try_or_fail!(self, self.get_number(at));
-
-                self.unify(a1, Addr::Con(Constant::Number(a2)));
-                try_or_fail!(self, return_from_clause!(self.last_call, self));
-            },
             &ControlInstruction::JmpBy(arity, offset, _, lco) => {
                 if !lco {
                     self.cp.assign_if_local(self.p.clone() + 1);

src/prolog/machine/mod.rs

@@ -233,7 +233,7 @@ impl Machine {
             CodePtr::Local(LocalCodePtr::DirEntry(p, _)) =>
                 Some(self.code[p].clone()),
             CodePtr::BuiltInClause(built_in, _) =>
-                Some(call_clause!(ClauseType::BuiltIn(built_in), built_in.arity(),
+                Some(call_clause!(ClauseType::BuiltIn(built_in.clone()), built_in.arity(),
                                   0, self.ms.last_call)),
             CodePtr::CallN(arity, _) =>
                 Some(call_clause!(ClauseType::CallN, arity, 0, self.ms.last_call))