225 lines
4.8 KiB
Prolog
225 lines
4.8 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 os.yap
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*/
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:- system_module( '$os', [
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cd/0,
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cd/1,
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getcwd/1,
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ls/0,
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pwd/0,
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unix/1,
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putenv/2,
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getenv/2,
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setenv/2
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], [] ).
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:- use_system_module( '$_errors', ['$do_error'/2]).
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/**
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@defgroup YAPOS Access to Operating System Functionality
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%% @{
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@ingroup builtins
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The following built-in predicates allow access to underlying
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Operating System functionality.
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*/
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/** @pred cd
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Changes the current directory (on UNIX environments) to the user's home directory.
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*/
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cd :-
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cd('~').
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/** @pred cd(+ _D_)
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Changes the current directory (on UNIX environments).
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*/
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cd(F) :-
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absolute_file_name(F, Dir, [file_type(directory),file_errors(fail),access(execute),expand(true)]),
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working_directory(_, Dir).
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/** @pred getcwd(- _D_)
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Unify the current directory, represented as an atom, with the argument
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_D_.
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*/
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getcwd(Dir) :- working_directory(Dir, Dir).
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/** @pred ls
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Prints a list of all files in the current directory.
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*/
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ls :-
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getcwd(X),
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'$load_system_ls'(X,L),
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'$do_print_files'(L).
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'$load_system_ls'(X,L) :-
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'$undefined'(directory_files(X, L), system),
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load_files(library(system),[silent(true)]),
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fail.
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'$load_system_ls'(X,L) :-
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system:directory_files(X, L).
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'$do_print_files'([]) :-
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nl.
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'$do_print_files'([F| Fs]) :-
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'$do_print_file'(F),
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'$do_print_files'(Fs).
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'$do_print_file'('.') :- !.
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'$do_print_file'('..') :- !.
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'$do_print_file'(F) :- atom_concat('.', _, F), !.
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'$do_print_file'(F) :-
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write(F), write(' ').
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/** @pred pwd
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Prints the current directory.
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*/
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pwd :-
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getcwd(X),
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write(X), nl.
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/** @pred unix(+ _S_)
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Access to Unix-like functionality:
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+ argv/1
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Return a list of arguments to the program. These are the arguments that
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follow a `--`, as in the usual Unix convention.
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+ cd/0
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Change to home directory.
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+ cd/1
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Change to given directory. Acceptable directory names are strings or
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atoms.
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+ environ/2
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If the first argument is an atom, unify the second argument with the
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value of the corresponding environment variable.
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+ getcwd/1
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Unify the first argument with an atom representing the current directory.
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+ putenv/2
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Set environment variable _E_ to the value _S_. If the
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environment variable _E_ does not exist, create a new one. Both the
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environment variable and the value must be atoms.
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+ shell/1
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Execute command under current shell. Acceptable commands are strings or
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atoms.
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+ system/1
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Execute command with `/bin/sh`. Acceptable commands are strings or
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atoms.
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+ shell/0
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Execute a new shell.
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*/
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unix(V) :- var(V), !,
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'$do_error'(instantiation_error,unix(V)).
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unix(argv(L)) :-
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current_prolog_flag(argv, L).
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unix(cd) :- cd('~').
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unix(cd(A)) :- cd(A).
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unix(environ(X,Y)) :- '$do_environ'(X,Y).
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unix(getcwd(X)) :- getcwd(X).
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unix(shell(V)) :- var(V), !,
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'$do_error'(instantiation_error,unix(shell(V))).
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unix(shell(A)) :- atom(A), !, '$shell'(A).
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unix(shell(A)) :- string(A), !, '$shell'(A).
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unix(shell(V)) :-
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'$do_error'(type_error(atomic,V),unix(shell(V))).
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unix(system(V)) :- var(V), !,
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'$do_error'(instantiation_error,unix(system(V))).
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unix(system(A)) :- atom(A), !, system(A).
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unix(system(A)) :- string(A), !, system(A).
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unix(system(V)) :-
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'$do_error'(type_error(atom,V),unix(system(V))).
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unix(shell) :- sh.
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unix(putenv(X,Y)) :- '$putenv'(X,Y).
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'$is_list_of_atoms'(V,_) :- var(V),!.
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'$is_list_of_atoms'([],_) :- !.
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'$is_list_of_atoms'([H|L],L0) :- !,
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'$check_if_head_may_be_atom'(H,L0),
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'$is_list_of_atoms'(L,L0).
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'$is_list_of_atoms'(H,L0) :-
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'$do_error'(type_error(list,H),unix(argv(L0))).
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'$check_if_head_may_be_atom'(H,_) :-
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var(H), !.
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'$check_if_head_may_be_atom'(H,_) :-
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atom(H), !.
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'$check_if_head_may_be_atom'(H,L0) :-
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'$do_error'(type_error(atom,H),unix(argv(L0))).
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'$do_environ'(X, Y) :-
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var(X), !,
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'$do_error'(instantiation_error,unix(environ(X,Y))).
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'$do_environ'(X, Y) :- atom(X), !,
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'$getenv'(X,Y).
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'$do_environ'(X, Y) :-
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'$do_error'(type_error(atom,X),unix(environ(X,Y))).
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/** @pred putenv(+ _E_,+ _S_)
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Set environment variable _E_ to the value _S_. If the
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environment variable _E_ does not exist, create a new one. Both the
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environment variable and the value must be atoms.
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*/
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putenv(Na,Val) :-
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'$putenv'(Na,Val).
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getenv(Na,Val) :-
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'$getenv'(Na,Val).
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/** @pred setenv(+ _Name_,+ _Value_)
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Set environment variable. _Name_ and _Value_ should be
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instantiated to atoms or integers. The environment variable will be
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passed to `shell/[0-2]` and can be requested using `getenv/2`.
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They also influence expand_file_name/2.
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*/
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setenv(Na,Val) :-
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'$putenv'(Na,Val).
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/**
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@}
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*/
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