159 lines
3.3 KiB
Prolog
159 lines
3.3 KiB
Prolog
/*************************************************************************
|
|
* *
|
|
* YAP Prolog *
|
|
* *
|
|
* Yap Prolog was developed at NCCUP - Universidade do Porto *
|
|
* *
|
|
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997 *
|
|
* *
|
|
**************************************************************************
|
|
* *
|
|
* File: terms.yap *
|
|
* Last rev: 5/12/99 *
|
|
* mods: *
|
|
* comments: Term manipulation operations *
|
|
* *
|
|
*************************************************************************/
|
|
/** @defgroup Terms Utilities On Terms
|
|
@ingroup library
|
|
@{
|
|
|
|
The next routines provide a set of commonly used utilities to manipulate
|
|
terms. Most of these utilities have been implemented in `C` for
|
|
efficiency. They are available through the
|
|
`use_module(library(terms))` command.
|
|
|
|
*/
|
|
/**
|
|
@pred cyclic_term(? _Term_)
|
|
|
|
|
|
Succeed if the argument _Term_ is not a cyclic term.
|
|
|
|
|
|
*/
|
|
|
|
|
|
/** @pred term_subsumer(? _T1_, ? _T2_, ? _Subsumer_)
|
|
|
|
|
|
|
|
Succeed if _Subsumer_ unifies with the least general
|
|
generalization over _T1_ and
|
|
_T2_.
|
|
|
|
|
|
*/
|
|
/** @pred new_variables_in_term(+ _Variables_,? _Term_, - _OutputVariables_)
|
|
|
|
|
|
|
|
Unify _OutputVariables_ with all variables occurring in _Term_ that are not in the list _Variables_.
|
|
|
|
|
|
*/
|
|
/** @pred subsumes(? _Term1_, ? _Term2_)
|
|
|
|
|
|
|
|
Succeed if _Term1_ subsumes _Term2_. Variables in term
|
|
_Term1_ are bound so that the two terms become equal.
|
|
|
|
|
|
*/
|
|
/** @pred subsumes_chk(? _Term1_, ? _Term2_)
|
|
|
|
|
|
|
|
Succeed if _Term1_ subsumes _Term2_ but does not bind any
|
|
variable in _Term1_.
|
|
|
|
|
|
*/
|
|
/** @pred term_hash(+ _Term_, + _Depth_, + _Range_, ? _Hash_)
|
|
|
|
|
|
Unify _Hash_ with a positive integer calculated from the structure
|
|
of the term. The range of the positive integer is from `0` to, but
|
|
not including, _Range_. If _Depth_ is `-1` the whole term
|
|
is considered. Otherwise, the term is considered only up to depth
|
|
`1`, where the constants and the principal functor have depth
|
|
`1`, and an argument of a term with depth _I_ has depth _I+1_.
|
|
|
|
|
|
*/
|
|
/** @pred term_hash(+ _Term_, ? _Hash_)
|
|
|
|
|
|
|
|
If _Term_ is ground unify _Hash_ with a positive integer
|
|
calculated from the structure of the term. Otherwise the argument
|
|
_Hash_ is left unbound. The range of the positive integer is from
|
|
`0` to, but not including, `33554432`.
|
|
|
|
|
|
*/
|
|
/** @pred unifiable(? _Term1_, ? _Term2_, - _Bindings_)
|
|
|
|
|
|
|
|
Succeed if _Term1_ and _Term2_ are unifiable with substitution
|
|
_Bindings_.
|
|
|
|
|
|
|
|
|
|
*/
|
|
/** @pred variable_in_term(? _Term_,? _Var_)
|
|
|
|
|
|
Succeed if the second argument _Var_ is a variable and occurs in
|
|
term _Term_.
|
|
|
|
|
|
*/
|
|
/** @pred variables_within_term(+ _Variables_,? _Term_, - _OutputVariables_)
|
|
|
|
|
|
|
|
Unify _OutputVariables_ with the subset of the variables _Variables_ that occurs in _Term_.
|
|
|
|
|
|
*/
|
|
/** @pred variant(? _Term1_, ? _Term2_)
|
|
|
|
|
|
|
|
Succeed if _Term1_ and _Term2_ are variant terms.
|
|
|
|
|
|
*/
|
|
:- module(terms, [
|
|
term_hash/2,
|
|
term_hash/4,
|
|
term_subsumer/3,
|
|
instantiated_term_hash/4,
|
|
variant/2,
|
|
unifiable/3,
|
|
subsumes/2,
|
|
subsumes_chk/2,
|
|
cyclic_term/1,
|
|
variable_in_term/2,
|
|
variables_within_term/3,
|
|
new_variables_in_term/3
|
|
]).
|
|
|
|
term_hash(T,H) :-
|
|
term_hash(T, -1, 33554432, H).
|
|
|
|
%term_hash(X,Y) :-
|
|
% term_hash(X,-1,16'1000000,Y).
|
|
|
|
subsumes_chk(X,Y) :-
|
|
\+ \+ subsumes(X,Y).
|
|
|
|
|
|
|
|
/** @} */
|
|
|