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