parse the list functor

src/prolog/ast.rs

@@ -22,6 +22,8 @@ pub type Var = String;
 
 pub type Specifier = u32;
 
+pub const MAX_ARITY: usize = 63;
+
 pub const XFX: u32 = 0x0001;
 pub const XFY: u32 = 0x0002;
 pub const YFX: u32 = 0x0004;

src/prolog/lib/builtins.pl

@@ -3,8 +3,8 @@
 :- module(builtins, [(=)/2, (+)/2, (*)/2, (-)/2, (/)/2, (/\)/2,
 	(\/)/2, (is)/2, (xor)/2, (div)/2, (//)/2, (rdiv)/2, (<<)/2,
 	(>>)/2, (mod)/2, (rem)/2, (>)/2, (<)/2, (=\=)/2, (=:=)/2,
-	(-)/1, (>=)/2, (=<)/2, (->)/2, (;)/2, (==)/2, (\==)/2, arg/3,
+	(-)/1, (>=)/2, (=<)/2, (,)/2, (->)/2, (;)/2, (==)/2, (\==)/2,
-	catch/3, throw/1, true/0, false/0, length/2]).
+	(=..)/2, arg/3, catch/3, throw/1, true/0, false/0, length/2]).
 
 % arithmetic operators.
 :- op(700, xfx, is).
@@ -33,6 +33,7 @@
 
 % unify.
 :- op(700, xfx, =).
+:- op(700, xfx, =..).
 
 % conditional operators.
 :- op(1050, xfy, ->).
@@ -105,14 +106,12 @@ length(Xs, N) :-
     '$skip_max_list'(M, -1, Xs, Xs0),
     (  Xs0 == [] -> N = M
     ;  var(Xs0)  -> '$length_addendum'(Xs0, N, M)).
-    % ;  throw(error(type_error(list, Xs), length/2))).
 length(Xs, N) :-
     integer(N),
     N >= 0, !,
     '$skip_max_list'(M, N, Xs, Xs0),
     (  Xs0 == [] -> N = M
     ;  var(Xs0)  -> R is N-M, '$length_rundown'(Xs0, R)).
-    % ;  throw(error(type_error(list, Xs), length/2))).
 length(_, N) :-
     integer(N), !,
     throw(error(domain_error(not_less_than_zero, N), length/2)).
@@ -128,3 +127,27 @@ length(_, N) :-
 '$length_rundown'([_|Xs], N) :-
     N1 is N-1,
     '$length_rundown'(Xs, N1).
+
+Term =.. List :-
+    atomic(Term), !,
+    List = [Term].
+Term =.. List :-
+    compound(Term), !,
+    ( functor(Term, Name, NArgs) ->
+      List = [Name|Args], '$get_args'(Args, Term, 1, NArgs)
+    ; Term = [_|_] ->
+      List = ['.'|Term] ).
+Term =.. List :-
+    var(Term), !,
+    ( List = [ATerm], atomic(ATerm) ->
+      Term = ATerm
+    ; List = [Name|Args] ->
+      functor(Term, Name, Args)).    
+
+'$get_args'(Args, _, _, 0) :-
+    !, Args = [].
+'$get_args'([Arg], Func, N, N) :-
+    !, '$get_arg'(N, Func, Arg).
+'$get_args'([Arg|Args], Func, I0, N) :-
+    '$get_arg'(I0, Func, Arg), I1 is I0 + 1,
+    '$get_args'(Args, Func, I1, N).

src/prolog/machine/machine_errors.rs

@@ -10,8 +10,8 @@ pub(super) type MachineStub = Vec<HeapCellValue>;
 // from 7.12.2 b) of 13211-1:1995
 #[derive(Clone, Copy)]
 pub enum ValidType {
-//    Atom,
+    Atom,
-//    Atomic,
+    Atomic,
 //    Byte,
     Callable,
 //    Character,
@@ -30,8 +30,8 @@ pub enum ValidType {
 impl ValidType {
     pub fn as_str(self) -> &'static str {
         match self {
-//            ValidType::Atom => "atom",
+            ValidType::Atom => "atom",
-//            ValidType::Atomic => "atomic",
+            ValidType::Atomic => "atomic",
 //            ValidType::Byte => "byte",
             ValidType::Callable => "callable",
 //            ValidType::Character => "character",
@@ -49,6 +49,19 @@ impl ValidType {
     }
 }
 
+#[derive(Clone, Copy)]
+pub enum DomainError {
+    NotLessThanZero
+}
+
+impl DomainError {
+    pub fn as_str(self) -> &'static str {
+        match self {
+            DomainError::NotLessThanZero => "not_less_than_zero"
+        }
+    }
+}
+
 // from 7.12.2 f) of 13211-1:1995
 #[derive(Clone, Copy)]
 pub enum RepFlag {
@@ -198,6 +211,10 @@ impl MachineState {
         error
     }
 
+    pub(super) fn domain_error(&self, error: DomainError, culprit: Addr) -> MachineError {
+        functor!("domain_error", 2, [heap_atom!(error.as_str()), HeapCellValue::Addr(culprit)])
+    }
+    
     pub(super) fn instantiation_error(&self) -> MachineError {
         functor!("instantiation_error")
     }

src/prolog/machine/machine_state_impl.rs

@@ -43,7 +43,7 @@ impl MachineState {
             mode: MachineMode::Write,
             and_stack: AndStack::new(),
             or_stack: OrStack::new(),
-            registers: vec![Addr::HeapCell(0); 64],
+            registers: vec![Addr::HeapCell(0); MAX_ARITY + 1], // self.registers[0] is never used.
             trail: Vec::new(),
             tr: 0,
             hb: 0,
@@ -168,6 +168,21 @@ impl MachineState {
                         self.bind(Ref::StackCell(fr, sc), d2),
                     (_, Addr::StackCell(fr, sc)) =>
                         self.bind(Ref::StackCell(fr, sc), d1),
+                    (Addr::Lis(a1), Addr::Str(a2)) | (Addr::Str(a2), Addr::Lis(a1)) => {
+                        if let &HeapCellValue::NamedStr(n2, ref f2, _) = &self.heap[a2] {
+                            if f2.as_str() == "." && n2 == 2 {
+                                pdl.push(Addr::HeapCell(a1));
+                                pdl.push(Addr::HeapCell(a2 + 1));
+
+                                pdl.push(Addr::HeapCell(a1 + 1));
+                                pdl.push(Addr::HeapCell(a2 + 2));
+
+                                continue;
+                            }
+                        }
+
+                        self.fail = true;
+                    },
                     (Addr::Lis(a1), Addr::Lis(a2)) => {
                         pdl.push(Addr::HeapCell(a1));
                         pdl.push(Addr::HeapCell(a2));
@@ -175,11 +190,10 @@ impl MachineState {
                         pdl.push(Addr::HeapCell(a1 + 1));
                         pdl.push(Addr::HeapCell(a2 + 1));
                     },
-                    (Addr::Con(c1), Addr::Con(c2)) => {
+                    (Addr::Con(c1), Addr::Con(c2)) =>
                         if c1 != c2 {
                             self.fail = true;
-                        }
+                        },                    
-                    },
                     (Addr::Str(a1), Addr::Str(a2)) => {
                         let r1 = &self.heap[a1];
                         let r2 = &self.heap[a2];
@@ -1415,69 +1429,91 @@ impl MachineState {
         }
     }
 
+    fn try_functor_unify_components(&mut self, name: Addr, arity: Addr) {
+        let a2 = self[temp_v!(2)].clone();
+        let a3 = self[temp_v!(3)].clone();
+
+        self.unify(a2, name);
+
+        if !self.fail {
+            self.unify(a3, arity);
+        }
+    }
+
+    fn try_functor_compound_case(&mut self, name: ClauseName, arity: usize) {
+        let name  = Addr::Con(Constant::Atom(name));
+        let arity = Addr::Con(integer!(arity));
+
+        self.try_functor_unify_components(name, arity);
+    }
+
     pub(super) fn try_functor(&mut self) -> Result<(), MachineError> {
         let stub = self.functor_stub(clause_name!("functor"), 3);
         let a1 = self.store(self.deref(self[temp_v!(1)].clone()));
 
         match a1.clone() {
+            Addr::Con(_) =>
+                self.try_functor_unify_components(a1, Addr::Con(integer!(0))),
             Addr::Str(o) =>
                 match self.heap[o].clone() {
-                    HeapCellValue::NamedStr(arity, name, _) => {
+                    HeapCellValue::NamedStr(arity, name, _) =>
-                        let name  = Addr::Con(Constant::Atom(name)); // A2
+                        self.try_functor_compound_case(name, arity),
-                        let arity = Addr::Con(Constant::Number(rc_integer!(arity)));
-
-                        let a2 = self[temp_v!(2)].clone();
-                        self.unify(a2, name);
-
-                        if !self.fail {
-                            let a3 = self[temp_v!(3)].clone();
-                            self.unify(a3, arity);
-                        }
-                    },
                     _ => self.fail = true
                 },
+            Addr::Lis(_) =>
+                self.try_functor_compound_case(clause_name!("."), 2),
             Addr::HeapCell(_) | Addr::StackCell(_, _) => {
                 let name  = self.store(self.deref(self[temp_v!(2)].clone()));
                 let arity = self.store(self.deref(self[temp_v!(3)].clone()));
 
-                if let Addr::Con(Constant::Atom(name)) = name {
+                if name.is_ref() || arity.is_ref() { // 8.5.1.3 a) & 8.5.1.3 b)
-                    if let Addr::Con(Constant::Number(Number::Integer(arity))) = arity {
-                        let f_a = Addr::Str(self.heap.h);
-                        let arity = match arity.to_usize() {
-                            Some(arity) => arity,
-                            None => {
-                                self.fail = true;
-                                return Ok(());
-                            }
-                        };
-
-                        if arity > 0 {
-                            self.heap.push(HeapCellValue::NamedStr(arity, name, None));
-                        } else {
-                            let c = Constant::Atom(name.clone());
-                            self.heap.push(HeapCellValue::Addr(Addr::Con(c)));
-                        }
-
-                        for _ in 0 .. arity {
-                            let h = self.heap.h;
-                            self.heap.push(HeapCellValue::Addr(Addr::HeapCell(h)));
-                        }
-
-                        self.unify(a1, f_a);
-                    } else {
-                        return Err(self.error_form(self.instantiation_error(), stub));
-                    }
-                } else {
                     return Err(self.error_form(self.instantiation_error(), stub));
                 }
-            },
-            _ => {
-                let a2 = self[temp_v!(2)].clone();
-                self.unify(a1, a2);
 
-                if !self.fail {
+                if let Addr::Con(Constant::Number(Number::Integer(arity))) = arity {
-                    let a3 = self[temp_v!(3)].clone();
+                    let arity = match arity.to_isize() {
-                    self.unify(a3, Addr::Con(Constant::Number(rc_integer!(0))));
+                        Some(arity) => arity,
+                        None => {
+                            self.fail = true;
+                            return Ok(());
+                        }
+                    };
+
+                    if arity > MAX_ARITY as isize {
+                        // 8.5.1.3 f)
+                        return Err(self.error_form(self.representation_error(RepFlag::MaxArity),
+                                                   stub));
+                    } else if arity < 0 {
+                        // 8.5.1.3 g)
+                        return Err(self.error_form(self.domain_error(DomainError::NotLessThanZero,
+                                                                     Addr::Con(integer!(arity))),
+                                                   stub));
+                    }
+
+                    match name {
+                        Addr::Con(_) if arity == 0 =>
+                            self.unify(a1, name),
+                        Addr::Con(Constant::Atom(name)) => {
+                            let f_a = Addr::Str(self.heap.h);
+                            self.heap.push(HeapCellValue::NamedStr(arity as usize, name, None));
+
+                            for _ in 0 .. arity {
+                                let h = self.heap.h;
+                                self.heap.push(HeapCellValue::Addr(Addr::HeapCell(h)));
+                            }
+
+                            self.unify(a1, f_a);
+                        },
+                        Addr::Con(_) =>
+                            return Err(self.error_form(self.type_error(ValidType::Atom, name),
+                                                       stub)), // 8.5.1.3 e)
+                        _ =>
+                            return Err(self.error_form(self.type_error(ValidType::Atomic, name),
+                                                       stub))  // 8.5.1.3 c)
+                    };
+                } else if !arity.is_ref() {
+                    // 8.5.1.3 d)
+                    return Err(self.error_form(self.type_error(ValidType::Integer, arity), stub));
                 }
             }
         };

src/prolog/macros.rs

@@ -164,12 +164,6 @@ macro_rules! integer {
     )
 }
 
-macro_rules! rc_integer {
-    ($e:expr) => (
-        Number::Integer(Rc::new(BigInt::from($e)))
-    )
-}
-
 macro_rules! rc_atom {
     ($e:expr) => (
         Rc::new(String::from($e))

src/tests.rs

@@ -1381,7 +1381,7 @@ fn test_queries_on_builtins()
     assert_prolog_success!(&mut wam, "?- length(Xs, 0).", [["Xs = []"]]);
     assert_prolog_success!(&mut wam, "?- length([a,b,[a,b,c]], 3).");
     assert_prolog_failure!(&mut wam, "?- length([a,b,[a,b,c]], 2).");
-    assert_prolog_success!(&mut wam, "?- catch(length(a, []), type_error(_, E), true).",
+    assert_prolog_success!(&mut wam, "?- catch(length(a, []), type_error(integer, E), true).",
                            [["E = []"]]);
 
     assert_prolog_success!(&mut wam, "?- duplicate_term([1,2,3], [X,Y,Z]).",