mercury/library/builtin.m

%---------------------------------------------------------------------------%
% Copyright (C) 1994-2004 The University of Melbourne.
% This file may only be copied under the terms of the GNU Library General
% Public License - see the file COPYING.LIB in the Mercury distribution.
%---------------------------------------------------------------------------%

% File: builtin.m.
% Main author: fjh.
% Stability: low.

% This file is automatically imported into every module.
% It is intended for things that are part of the language,
% but which are implemented just as normal user-level code
% rather than with special coding in the compiler.

%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%

:- module builtin.
:- interface.

%-----------------------------------------------------------------------------%

% TYPES.

% The types `character', `int', `float', and `string',
% and tuple types `{}', `{T}', `{T1, T2}', ...
% and the types `pred', `pred(T)', `pred(T1, T2)', `pred(T1, T2, T3)', ...
% and `func(T1) = T2', `func(T1, T2) = T3', `func(T1, T2, T3) = T4', ...
% are builtin and are implemented using special code in the
% type-checker.  (XXX TODO: report an error for attempts to redefine
% these types.)

% The type c_pointer can be used by predicates which use the C interface.
:- type c_pointer.

%-----------------------------------------------------------------------------%

% INSTS.

% The standard insts `free', `ground', and `bound(...)' are builtin
% and are implemented using special code in the parser and mode-checker.

% So are the standard unique insts `unique', `unique(...)',
% `mostly_unique', `mostly_unique(...)', and `clobbered'.
% The name `dead' is allowed as a synonym for `clobbered'.
% Similarly `mostly_dead' is a synonym for `mostly_clobbered'.

:- inst dead = clobbered.
:- inst mostly_dead = mostly_clobbered.

% The `any' inst used for the constraint solver interface is also builtin.

% Higher-order predicate insts `pred(<modes>) is <detism>'
% and higher-order functions insts `func(<modes>) = <mode> is det'
% are also builtin.

%-----------------------------------------------------------------------------%

% MODES.

% The standard modes.

:- mode unused :: (free -> free).
:- mode output :: (free -> ground).
:- mode input :: (ground -> ground).

:- mode in :: (ground -> ground).
:- mode out :: (free -> ground).

:- mode in(Inst) :: (Inst -> Inst).
:- mode out(Inst) :: (free -> Inst).
:- mode di(Inst) :: (Inst -> clobbered).
:- mode mdi(Inst) :: (Inst -> mostly_clobbered).

% Unique modes.  These are still not fully implemented.

% unique output
:- mode uo :: free -> unique.

% unique input
:- mode ui :: unique -> unique.

% destructive input
:- mode di :: unique -> clobbered.

% "Mostly" unique modes (unique except that that may be referenced
% again on backtracking).

% mostly unique output
:- mode muo :: free -> mostly_unique.

% mostly unique input
:- mode mui :: mostly_unique -> mostly_unique.

% mostly destructive input
:- mode mdi :: mostly_unique -> mostly_clobbered.

% Higher-order predicate modes are builtin.

%-----------------------------------------------------------------------------%

% PREDICATES.

% Most of these probably ought to be moved to another
% module in the standard library such as std_util.m.

% copy/2 makes a deep copy of a data structure.  The resulting copy is a
% `unique' value, so you can use destructive update on it.

:- pred copy(T, T).
:- mode copy(ui, uo) is det.
:- mode copy(in, uo) is det.

% unsafe_promise_unique/2 is used to promise the compiler that you have a
% `unique' copy of a data structure, so that you can use destructive update.
% It is used to work around limitations in the current support for unique
% modes.  `unsafe_promise_unique(X, Y)' is the same as `Y = X' except that
% the compiler will assume that `Y' is unique.
%
% Note that misuse of this predicate may lead to unsound results:
% if there is more than one reference to the data in question,
% i.e. it is not `unique', then the behaviour is undefined.
% (If you lie to the compiler, the compiler will get its revenge!)

:- pred unsafe_promise_unique(T, T).
:- mode unsafe_promise_unique(in, uo) is det.

:- func unsafe_promise_unique(T) = T.
:- mode unsafe_promise_unique(in) = uo is det.

% A synonym for fail/0; the name is more in keeping with Mercury's
% declarative style rather than its Prolog heritage.

:- pred false.
:- mode false is failure.

%-----------------------------------------------------------------------------%

% A call to the function `promise_only_solution(Pred)' constitutes a
% promise on the part of the caller that `Pred' has at most one solution,
% i.e. that `not some [X1, X2] (Pred(X1), Pred(X2), X1 \= X2)'.
% `promise_only_solution(Pred)' presumes that this assumption is
% satisfied, and returns the X for which Pred(X) is true, if
% there is one.
%
% You can use `promise_only_solution' as a way of 
% introducing `cc_multi' or `cc_nondet' code inside a
% `det' or `semidet' procedure.
%
% Note that misuse of this function may lead to unsound results:
% if the assumption is not satisfied, the behaviour is undefined.
% (If you lie to the compiler, the compiler will get its revenge!)

:- func promise_only_solution(pred(T)) = T.
:- mode promise_only_solution(pred(out) is cc_multi) = out is det.
:- mode promise_only_solution(pred(uo) is cc_multi) = uo is det.
:- mode promise_only_solution(pred(out) is cc_nondet) = out is semidet.
:- mode promise_only_solution(pred(uo) is cc_nondet) = uo is semidet.

% `promise_only_solution_io' is like `promise_only_solution', but
% for procedures with unique modes (e.g. those that do IO).
%
% A call to `promise_only_solution_io(P, X, IO0, IO)' constitutes
% a promise on the part of the caller that for the given IO0,
% there is only one value of `X' and `IO' for which `P(X, IO0, IO)' is true.
% `promise_only_solution_io(P, X, IO0, IO)' presumes that this assumption
% is satisfied, and returns the X and IO for which `P(X, IO0, IO)' is true.
%
% Note that misuse of this predicate may lead to unsound results:
% if the assumption is not satisfied, the behaviour is undefined.
% (If you lie to the compiler, the compiler will get its revenge!)

:- pred promise_only_solution_io(pred(T, IO, IO), T, IO, IO).
:- mode promise_only_solution_io(pred(out, di, uo) is cc_multi,
		out, di, uo) is det.

%-----------------------------------------------------------------------------%

	% unify(X, Y) is true iff X = Y.
:- pred unify(T::in, T::in) is semidet.

	% For use in defining user-defined unification predicates.
	% The relation defined by a value of type `unify', must be an
	% equivalence relation; that is, it must be symmetric, reflexive,
	% and transitive. 
:- type unify(T) == pred(T, T).
:- inst unify == (pred(in, in) is semidet).

:- type comparison_result ---> (=) ; (<) ; (>).

	% compare(Res, X, Y) binds Res to =, <, or >
	% depending on wheither X is =, <, or > Y in the
	% standard ordering.
:- pred compare(comparison_result, T, T).
	% Note to implementors: the modes must appear in this order:
	% compiler/higher_order.m depends on it, as does
	% compiler/simplify.m (for the inequality simplification.)
:- mode compare(uo, in, in) is det.
:- mode compare(uo, ui, ui) is det.
:- mode compare(uo, ui, in) is det.
:- mode compare(uo, in, ui) is det.

	% For use in defining user-defined comparison predicates.
	% For a value `ComparePred' of type `compare', the following
	% conditions must hold:
	%
	% - the relation
	%	compare_eq(X, Y) :- ComparePred((=), X, Y).
	%   must be an equivalence relation; that is, it must be symmetric,
	%   reflexive, and transitive. 
	%
	% - the relations
	%	compare_leq(X, Y) :-
	%		ComparePred(R, X, Y), (R = (=) ; R = (<)).
	%	compare_geq(X, Y) :-
	%		ComparePred(R, X, Y), (R = (=) ; R = (>)).
	%   must be total order relations: that is they must be antisymmetric,
	%   reflexive and transitive.
:- type compare(T) == pred(comparison_result, T, T).
:- inst compare == (pred(uo, in, in) is det).

	% ordering(X, Y) = R <=> compare(R, X, Y)
	%
:- func ordering(T, T) = comparison_result.

	% The standard inequalities defined in terms of compare/3.
	% XXX The ui modes are commented out because they don't yet
	% work properly.
	%
:- pred T  @<  T.
:- mode in @< in is semidet.
% :- mode ui @< in is semidet.
% :- mode in @< ui is semidet.
% :- mode ui @< ui is semidet.

:- pred T  @=<  T.
:- mode in @=< in is semidet.
% :- mode ui @=< in is semidet.
% :- mode in @=< ui is semidet.
% :- mode ui @=< ui is semidet.

:- pred T  @>  T.
:- mode in @> in is semidet.
% :- mode ui @> in is semidet.
% :- mode in @> ui is semidet.
% :- mode ui @> ui is semidet.

:- pred T  @>=  T.
:- mode in @>= in is semidet.
% :- mode ui @>= in is semidet.
% :- mode in @>= ui is semidet.
% :- mode ui @>= ui is semidet.

	% Values of types comparison_pred/1 and comparison_func/1 are used
	% by predicates and functions which depend on an ordering on a given
	% type, where this ordering is not necessarily the standard ordering.
	% In addition to the type, mode and determinism constraints, a
	% comparison predicate C is expected to obey two other laws.
	% For all X, Y and Z of the appropriate type, and for all
	% comparison_results R:
	%	1) C(X, Y, (>)) if and only if C(Y, X, (<))
	%	2) C(X, Y, R) and C(Y, Z, R) implies C(X, Z, R).
	% Comparison functions are expected to obey analogous laws.
	%
	% Note that binary relations <, > and = can be defined from a
	% comparison predicate or function in an obvious way.  The following
	% facts about these relations are entailed by the above constraints:
	% = is an equivalence relation (not necessarily the usual equality),
	% and the equivalence classes of this relation are totally ordered
	% with respect to < and >.
:- type comparison_pred(T) == pred(T, T, comparison_result).
:- inst comparison_pred(I) == (pred(in(I), in(I), out) is det).
:- inst comparison_pred == comparison_pred(ground).

:- type comparison_func(T) == (func(T, T) = comparison_result).
:- inst comparison_func(I) == (func(in(I), in(I)) = out is det).
:- inst comparison_func == comparison_func(ground).

% In addition, the following predicate-like constructs are builtin:
%
%	:- pred (T = T).
%	:- pred (T \= T).
%	:- pred (pred , pred).
%	:- pred (pred ; pred).
%	:- pred (\+ pred).
%	:- pred (not pred).
%	:- pred (pred -> pred).
%	:- pred (if pred then pred).
%	:- pred (if pred then pred else pred).
%	:- pred (pred => pred).
%	:- pred (pred <= pred).
%	:- pred (pred <=> pred).
%
%	(pred -> pred ; pred).
%	some Vars pred
%	all Vars pred
%	call/N

%-----------------------------------------------------------------------------%
:- implementation.

% Everything below here is not intended to be part of the public interface,
% and will not be included in the Mercury library reference manual.

%-----------------------------------------------------------------------------%
:- interface.

% `get_one_solution' and `get_one_solution_io' are impure alternatives
% to `promise_one_solution' and `promise_one_solution_io', respectively.
% They get a solution to the procedure, without requiring any promise
% that there is only one solution.  However, they can only be used in
% impure code.

:- impure func get_one_solution(pred(T)) = T.
:-        mode get_one_solution(pred(out) is cc_multi) = out is det.
:-        mode get_one_solution(pred(out) is cc_nondet) = out is semidet.

:- impure pred get_one_solution_io(pred(T, IO, IO), T, IO, IO).
:-        mode get_one_solution_io(pred(out, di, uo) is cc_multi,
		out, di, uo) is det.

% compare_representation(Result, X, Y)
%
% compare_representation is similar to the builtin predicate
% compare/3, except that it does not abort when asked to compare
% non-canonical terms.
%
% The declarative semantics of compare_representation for unequal
% non-canonical terms is that the result is either (<) or (>).
% For equal non-canonical terms the result can be anything.
%
% Operationally, the result of compare_representation for
% non-canonical terms is the same as that for comparing the internal
% representations of the terms, where the internal representation is
% that which would be produced by deconstruct__cc.
%
% XXX This predicate is not yet implemented for highlevel code.
% This is the reason it is not in the official part of the interface.

:- pred compare_representation(comparison_result, T, T).
:- mode compare_representation(uo, in, in) is cc_multi.

:- implementation.
:- import_module require, string, std_util, int, float, char, string, list.

%-----------------------------------------------------------------------------%

false :- fail.

%-----------------------------------------------------------------------------%

% XXX The calls to unsafe_promise_unique below work around
% mode checker limitations.
:- pragma promise_pure(promise_only_solution/1).
promise_only_solution(CCPred::(pred(out) is cc_multi)) = (OutVal::out) :-
	impure OutVal = get_one_solution(CCPred).
promise_only_solution(CCPred::(pred(uo) is cc_multi)) = (OutVal::uo) :-
	impure OutVal0 = get_one_solution(CCPred),
	OutVal = unsafe_promise_unique(OutVal0).
promise_only_solution(CCPred::(pred(out) is cc_nondet)) = (OutVal::out) :-
	impure OutVal = get_one_solution(CCPred).
promise_only_solution(CCPred::(pred(uo) is cc_nondet)) = (OutVal::uo) :-
	impure OutVal0 = get_one_solution(CCPred),
	OutVal = unsafe_promise_unique(OutVal0).

get_one_solution(CCPred) = OutVal :-
	impure Pred = cc_cast(CCPred),
	call(Pred, OutVal).

:- impure func cc_cast(pred(T)) = pred(T).
:- mode cc_cast(pred(out) is cc_nondet) = out(pred(out) is semidet) is det.
:- mode cc_cast(pred(out) is cc_multi) = out(pred(out) is det) is det.

:- pragma foreign_proc("C",
	cc_cast(X :: (pred(out) is cc_multi)) = (Y :: out(pred(out) is det)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").
:- pragma foreign_proc("C",
	cc_cast(X :: (pred(out) is cc_nondet)) =
		(Y :: out(pred(out) is semidet)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").
:- pragma foreign_proc("C#",
	cc_cast(X :: (pred(out) is cc_multi)) = (Y :: out(pred(out) is det)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").
:- pragma foreign_proc("C#",
	cc_cast(X :: (pred(out) is cc_nondet)) =
		(Y :: out(pred(out) is semidet)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").
:- pragma foreign_proc("Java",
	cc_cast(X :: (pred(out) is cc_multi)) = (Y :: out(pred(out) is det)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").
:- pragma foreign_proc("Java",
	cc_cast(X :: (pred(out) is cc_nondet)) =
		(Y :: out(pred(out) is semidet)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").

:- pragma promise_pure(promise_only_solution_io/4).
promise_only_solution_io(Pred, X) -->
	impure get_one_solution_io(Pred, X).

get_one_solution_io(Pred, X) -->
	{ impure DetPred = cc_cast_io(Pred) },
	call(DetPred, X).

:- impure func cc_cast_io(pred(T, IO, IO)) = pred(T, IO, IO).
:- mode cc_cast_io(pred(out, di, uo) is cc_multi) =
	out(pred(out, di, uo) is det) is det.

:- pragma foreign_proc("C",
	cc_cast_io(X :: (pred(out, di, uo) is cc_multi)) = 
		(Y :: out(pred(out, di, uo) is det)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").
:- pragma foreign_proc("C#", 
	cc_cast_io(X :: (pred(out, di, uo) is cc_multi)) =
		(Y :: out(pred(out, di, uo) is det)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").
:- pragma foreign_proc("Java", 
	cc_cast_io(X :: (pred(out, di, uo) is cc_multi)) =
		(Y :: out(pred(out, di, uo) is det)),
	[will_not_call_mercury, thread_safe],
"
	Y = X;
").

%-----------------------------------------------------------------------------%

:- external(unify/2).
:- external(compare/3).
:- external(compare_representation/3).

ordering(X, Y) = R :-
	compare(R, X, Y).

	% simplify__goal automatically inlines these definitions.
	%
X  @< Y :- compare((<), X, Y).
X @=< Y :- not compare((>), X, Y).
X @>  Y :- compare((>), X, Y).
X @>= Y :- not compare((<), X, Y).

%-----------------------------------------------------------------------------%

:- pragma foreign_decl("C", "#include ""mercury_type_info.h""").

:- interface.
:- pred call_rtti_generic_unify(T::in, T::in) is semidet.
:- pred call_rtti_generic_compare(comparison_result::out, T::in, T::in) is det.
:- implementation.
:- use_module rtti_implementation.

call_rtti_generic_unify(X, Y) :-
	rtti_implementation__generic_unify(X, Y).
call_rtti_generic_compare(Res, X, Y) :-
	rtti_implementation__generic_compare(Res, X, Y).

:- pragma foreign_code("C#", "

public static void compare_3(object[] TypeInfo_for_T,
		ref object[] Res, object X, object Y) 
{
	mercury.builtin.mercury_code.call_rtti_generic_compare_3(
			TypeInfo_for_T, ref Res, X, Y);
}

public static void compare_3_m1(object[] TypeInfo_for_T,
		ref object[] Res, object X, object Y) 
{
	compare_3(TypeInfo_for_T, ref Res, X, Y);
}

public static void compare_3_m2(object[] TypeInfo_for_T,
		ref object[] Res, object X, object Y) 
{
	compare_3(TypeInfo_for_T, ref Res, X, Y);
}

public static void compare_3_m3(object[] TypeInfo_for_T,
		ref object[] Res, object X, object Y) 
{
	compare_3(TypeInfo_for_T, ref Res, X, Y);
}
").

:- pragma foreign_code("C#", "
public static object deep_copy(object o)
{
	System.Type t = o.GetType();

	if (t.IsValueType) {
		return o;
	} else if (t == typeof(string)) {
		// XXX For some reason we need to handle strings specially.
		// It is probably something to do with the fact that they
		// are a builtin type.
		string s;
		s = (string) o;
		return s;
	} else {
		object n;

		// This will do a bitwise shallow copy of the object.
		n = t.InvokeMember(""MemberwiseClone"",
			System.Reflection.BindingFlags.Instance |
			System.Reflection.BindingFlags.NonPublic |
			System.Reflection.BindingFlags.InvokeMethod,
			null, o, new object[] {});

		// Set each of the fields to point to a deep copy of the
		// field.
		deep_copy_fields(t.GetFields(
				System.Reflection.BindingFlags.Public |
				System.Reflection.BindingFlags.Instance),
				n, o);

		// XXX This requires that mercury.dll have
		// System.Security.Permissions.ReflectionPermission
		// so that the non-public fields are accessible.
		deep_copy_fields(t.GetFields(
				System.Reflection.BindingFlags.NonPublic |
				System.Reflection.BindingFlags.Instance),
				n, o);

		return n;
	}
}

public static void deep_copy_fields(
		System.Reflection.FieldInfo[] fields, object dest, object src)
{
	// XXX We don't handle init-only fields, but I can't think of a way.
	foreach (System.Reflection.FieldInfo f in fields)
	{
		f.SetValue(dest, deep_copy(f.GetValue(src)));
	}
}

").

:- pragma foreign_code("C#", "

public static bool unify_2_p(object[] ti, object X, object Y) 
{
	return mercury.builtin.mercury_code.call_rtti_generic_unify_2_p(
			ti, X, Y);
}

").

:- pragma foreign_code("C#", "
	
public static bool
special__Unify____void_0_0(object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called unify for type `void'"");
	return false;
}

public static bool
special___Unify___c_pointer_0_0(object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called unify for type `c_pointer'"");
	return false;
}

public static bool
special__Unify____func_0_0(object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called unify for `func' type"");
	return false;
}

public static bool
special__Unify____tuple_0_0(object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called unify for `tuple' type"");
	return false;
}

public static void
special__Compare____void_0_0(ref object[] result,
	object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called compare/3 for type `void'"");
}

public static void
special__Compare____c_pointer_0_0(
	ref object[] result, object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called compare/3 for type `c_pointer'"");
}

public static void
special__Compare____func_0_0(ref object[] result,
	object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called compare/3 for `func' type"");
}

public static void
special__Compare____tuple_0_0(ref object[] result,
	object[] x, object[] y)
{
	mercury.runtime.Errors.fatal_error(
		""called compare/3 for `tuple' type"");
}

").

:- pragma foreign_code("Java",
"
public static java.lang.Object
deep_copy(java.lang.Object original) {
	java.lang.Object clone;

	if (original == null) {
		return null;
	}

	java.lang.Class cls = original.getClass();

	if (cls.getName().equals(""java.lang.String"")) {
		return new java.lang.String((java.lang.String) original);
	}

	if (cls.isArray()) {
		int length = java.lang.reflect.Array.getLength(original);
		clone = java.lang.reflect.Array.newInstance(
				cls.getComponentType(), length);
		for (int i = 0; i < length; i++) {
			java.lang.Object X, Y;
			X = java.lang.reflect.Array.get(original, i);
			Y = deep_copy(X);
			java.lang.reflect.Array.set(clone, i, Y);
		}
		return clone;
	}

	/*
	** XXX Two possible approaches are possible here:
	**
	** 1. Get all mercury objects to implement the Serializable interface.
	**    Then this whole function could be replaced with code that writes
	**    the Object out via an ObjectOutputStream into a byte array (or
	**    something), then reads it back in again, thus creating a copy.
	** 2. Call cls.getConstructors(), then iterate through the resulting
	**    array until one of them allows instantiation with all parameters
	**    set to 0 or null (or some sort of recursive call that attempts to
	**    instantiate the parameters).
	**    This approach is of course not guaranteed to work all the time.
	**    Then we can just copy the fields across using Reflection.
	**
	** For now, we're just throwing an exception.
	*/

	throw new java.lang.RuntimeException(
			""deep copy not yet fully implemented"");
}
").

%-----------------------------------------------------------------------------%

% unsafe_promise_unique is a compiler builtin.

%-----------------------------------------------------------------------------%

:- pragma foreign_proc("C",
	copy(Value::ui, Copy::uo),
	[will_not_call_mercury, thread_safe, promise_pure],
"
	MR_save_transient_registers();
	Copy = MR_deep_copy(Value, (MR_TypeInfo) TypeInfo_for_T, NULL, NULL);
	MR_restore_transient_registers();
").

:- pragma foreign_proc("C",
	copy(Value::in, Copy::uo),
	[will_not_call_mercury, thread_safe, promise_pure],
"
	MR_save_transient_registers();
	Copy = MR_deep_copy(Value, (MR_TypeInfo) TypeInfo_for_T, NULL, NULL);
	MR_restore_transient_registers();
").

:- pragma foreign_proc("C#",
	copy(X::ui, Y::uo),
	[may_call_mercury, thread_safe, promise_pure, terminates],
"
        Y = deep_copy(X);
").

:- pragma foreign_proc("C#",
	copy(X::in, Y::uo),
	[may_call_mercury, thread_safe, promise_pure, terminates],
"
        Y = deep_copy(X);
").

:- pragma foreign_proc("Java",
	copy(X::ui, Y::uo),
	[may_call_mercury, thread_safe, promise_pure, terminates],
"
        Y = deep_copy(X);
").

:- pragma foreign_proc("Java",
	copy(X::in, Y::uo),
	[may_call_mercury, thread_safe, promise_pure, terminates],
"
        Y = deep_copy(X);
").

%-----------------------------------------------------------------------------%

% 
% A definition of the Mercury type void/0 is needed because we can generate
% references to it in code.  See tests/hard_coded/nullary_ho_func.m for an
% example of code which does.
%
:- pragma foreign_decl("C#", "
namespace mercury.builtin {
	public class void_0
	{
		// Make the constructor private to ensure that we can
		// never create an instance of this class.
		private void_0()
		{
		}
	}
}
").
:- pragma foreign_code("Java", "
	public static class void_0
	{
		// Make the constructor private to ensure that we can
		// never create an instance of this class.
		private void_0()
		{
		}
	}
").

%-----------------------------------------------------------------------------%

:- pragma foreign_code("Java", "

	//
	// Definitions of builtin types
	//

	public static class tuple_0
	{
		// stub only
	}

	public static class func_0
	{
		// stub only
	}

	public static class c_pointer_0
	{
		// stub only
	}

	//
	// Generic unification/comparison routines
	//

	public static boolean
	unify_2_p_0 (mercury.runtime.TypeInfo_Struct ti,
		     java.lang.Object x, java.lang.Object y)
	{
		// stub only
		throw new java.lang.Error (""unify/3 not implemented"");
	}

	public static comparison_result_0
	compare_3_p_0 (mercury.runtime.TypeInfo_Struct ti,
		       java.lang.Object x, java.lang.Object y)
	{
		// stub only
		throw new java.lang.Error (""compare/3 not implemented"");
	}

	public static comparison_result_0
	compare_3_p_1 (mercury.runtime.TypeInfo_Struct ti,
		       java.lang.Object x, java.lang.Object y)
	{
		return compare_3_p_0(ti, x, y);
	}

	public static comparison_result_0
	compare_3_p_2 (mercury.runtime.TypeInfo_Struct ti,
		       java.lang.Object x, java.lang.Object y)
	{
		return compare_3_p_0(ti, x, y);
	}

	public static comparison_result_0
	compare_3_p_3 (mercury.runtime.TypeInfo_Struct ti,
		       java.lang.Object x, java.lang.Object y)
	{
		return compare_3_p_0(ti, x, y);
	}

	public static comparison_result_0
	compare_representation_3_p_0 (mercury.runtime.TypeInfo_Struct ti,
		       java.lang.Object x, java.lang.Object y)
	{
		// stub only
		throw new java.lang.Error (
			""compare_representation_3_p_0/3 not implemented"");
	}

	//
	// Type-specific unification routines for builtin types
	//

	public static boolean
	__Unify____tuple_0_0
		(mercury.builtin.tuple_0 x, mercury.builtin.tuple_0 y)
	{
		// stub only
		throw new java.lang.Error (""unify/2 for tuple types not implemented"");
	}

	public static boolean
	__Unify____func_0_0
		(mercury.builtin.func_0 x, mercury.builtin.func_0 y)
	{
		// stub only
		throw new java.lang.Error (""unify/2 for tuple types not implemented"");
	}


	public static boolean
	__Unify____c_pointer_0_0
		(java.lang.Object x, java.lang.Object y)
	{
		// XXX should we try calling a Java comparison routine?
		throw new java.lang.Error (""unify/2 called for c_pointer type"");
	}

	public static boolean
	__Unify____void_0_0
		(mercury.builtin.void_0 x, mercury.builtin.void_0 y)
	{
		// there should never be any values of type void/0
		throw new java.lang.Error (""unify/2 called for void type"");
	}

	//
	// Type-specific comparison routines for builtin types
	//

	public static comparison_result_0
	__Compare____tuple_0_0
		(mercury.builtin.tuple_0 x, mercury.builtin.tuple_0 y)
	{
		// stub only
		throw new java.lang.Error
			(""compare/3 for tuple types not implemented"");
	}

	public static comparison_result_0
	__Compare____func_0_0
		(mercury.builtin.func_0 x, mercury.builtin.func_0 y)
	{
		// comparing values of higher-order types is a run-time error
		throw new java.lang.Error (""compare/3 called for func type"");
	}

	public static comparison_result_0
	__Compare____c_pointer_0_0
		(java.lang.Object x, java.lang.Object y)
	{
		// XXX should we try calling a Java comparison routine?
		throw new java.lang.Error
			(""compare/3 called for c_pointer type"");
	}

	public static comparison_result_0
	__Compare____void_0_0
		(mercury.builtin.void_0 x, mercury.builtin.void_0 y)
	{
		// there should never be any values of type void/0
		throw new java.lang.Error (""compare/3 called for void type"");
	}
").

:- end_module builtin.

%-----------------------------------------------------------------------------%