115 lines
2.9 KiB
Plaintext
115 lines
2.9 KiB
Plaintext
|
|
||
|
|
/*
|
||
|
|
This file contains an adaptation to Logtalk of code for logical assignment
|
||
|
|
of Prolog terms developed by Nobukuni Kino. For more information, please
|
||
|
|
consult the URL http://www.kprolog.com/en/logical_assignment/
|
||
|
|
|
||
|
|
As a derivative work, this file is licensed under the Open Software License
|
||
|
|
version 2.1 (http://opensource.org/licenses/osl-2.1.php).
|
||
|
|
*/
|
||
|
|
|
||
|
|
|
||
|
|
:-op(100, xfx, '<=').
|
||
|
|
:-op(100, xfx, '=>').
|
||
|
|
|
||
|
|
|
||
|
|
:- category(assignvars).
|
||
|
|
|
||
|
|
|
||
|
|
:- info([
|
||
|
|
version is 1.0,
|
||
|
|
author is 'Nobukuni Kino and Paulo Moura',
|
||
|
|
date is 2005/1/7,
|
||
|
|
comment is 'Assignable variables (supporting logical, backtracable assignement of non-variable terms).']).
|
||
|
|
|
||
|
|
|
||
|
|
:- public(assignable/1).
|
||
|
|
:- mode(assignable(-assignvar), one).
|
||
|
|
:- info(assignable/1, [
|
||
|
|
comment is 'Makes Variable an assignable variable. Initial state will be empty.',
|
||
|
|
argnames is ['Variable'],
|
||
|
|
exceptions is [
|
||
|
|
'Variable is not a variable' - type_error(variable, 'Variable')]]).
|
||
|
|
|
||
|
|
:- public(assignable/2).
|
||
|
|
:- mode(assignable(-assignvar, @nonvar), one).
|
||
|
|
:- info(assignable/2, [
|
||
|
|
comment is 'Makes Variable an assignable variable and sets its initial state to Value.',
|
||
|
|
argnames is ['Variable', 'Value'],
|
||
|
|
exceptions is [
|
||
|
|
'Variable is not a variable' - type_error(variable, 'Variable'),
|
||
|
|
'Value is not instantiated' - instantiation_error]]).
|
||
|
|
|
||
|
|
:- public((<=)/2).
|
||
|
|
:- mode(<=(?assignvar, @nonvar), one).
|
||
|
|
:- info((<=)/2, [
|
||
|
|
comment is 'Sets the state of the assignable variable Variable to Value (initializing the variable if needed).',
|
||
|
|
argnames is ['Variable', 'Value'],
|
||
|
|
exceptions is [
|
||
|
|
'Value is not instantiated' - instantiation_error]]).
|
||
|
|
|
||
|
|
:- public((=>)/2).
|
||
|
|
:- mode(=>(+assignvar, ?nonvar), zero_or_one).
|
||
|
|
:- info((=>)/2, [
|
||
|
|
comment is 'Unifies Value with the current state of the assignable variable Variable.',
|
||
|
|
argnames is ['Variable', 'Value'],
|
||
|
|
exceptions is [
|
||
|
|
'Variable is not instantiated' - instantiation_error]]).
|
||
|
|
|
||
|
|
|
||
|
|
:-op(100, xfx, <=).
|
||
|
|
:-op(100, xfx, =>).
|
||
|
|
|
||
|
|
|
||
|
|
assignable(Assig) :-
|
||
|
|
nonvar(Assig),
|
||
|
|
self(Self),
|
||
|
|
sender(Sender),
|
||
|
|
throw(error(type_error(variable, Assig), Self::assignable(Assig), Sender)).
|
||
|
|
|
||
|
|
assignable([_| _]).
|
||
|
|
|
||
|
|
|
||
|
|
assignable(Assig, Init) :-
|
||
|
|
nonvar(Assig),
|
||
|
|
self(Self),
|
||
|
|
sender(Sender),
|
||
|
|
throw(error(type_error(variable, Assig), Self::assignable(Assig, Init), Sender)).
|
||
|
|
|
||
|
|
assignable(Assig, Init) :-
|
||
|
|
var(Init),
|
||
|
|
self(Self),
|
||
|
|
sender(Sender),
|
||
|
|
throw(error(instantiation_error, Self::assignable(Assig, Init), Sender)).
|
||
|
|
|
||
|
|
assignable([_, Init| _], Init).
|
||
|
|
|
||
|
|
|
||
|
|
Assig <= Value :-
|
||
|
|
var(Value),
|
||
|
|
self(Self),
|
||
|
|
sender(Sender),
|
||
|
|
throw(error(instantiation_error, Self::Assig <= Value, Sender)).
|
||
|
|
|
||
|
|
[_| Tail] <= Value :-
|
||
|
|
nonvar(Tail) ->
|
||
|
|
Tail <= Value
|
||
|
|
;
|
||
|
|
Tail = [Value| _].
|
||
|
|
|
||
|
|
|
||
|
|
Assig => Value :-
|
||
|
|
var(Assig),
|
||
|
|
self(Self),
|
||
|
|
sender(Sender),
|
||
|
|
throw(error(instantiation_error, Self::Assig => Value, Sender)).
|
||
|
|
|
||
|
|
[Current| Tail] => Value :-
|
||
|
|
nonvar(Tail) ->
|
||
|
|
Tail => Value
|
||
|
|
;
|
||
|
|
Current = Value.
|
||
|
|
|
||
|
|
|
||
|
|
:- end_category.
|