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yap-6.3/pl/yio.yap
Vitor Santos Costa faf3c930c8 docs
2017-04-07 23:10:59 +01:00

465 lines
10 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: yio.yap *
* Last rev: *
* mods: *
* comments: Input output predicates *
* *
*************************************************************************/
:- system_module( '$_yio', [at_end_of_line/0,
at_end_of_line/1,
consult_depth/1,
current_char_conversion/2,
current_line_number/1,
current_line_number/2,
current_stream/3,
display/1,
display/2,
exists/1,
fileerrors/0,
format/1,
nofileerrors/0,
open_pipe_streams/2,
prolog_file_name/2,
read/1,
read/2,
sformat/3,
socket/2,
socket/4,
socket_connect/3,
stream_position/2,
stream_position/3,
stream_position_data/3,
ttyget/1,
ttyget0/1,
ttynl/0,
ttyput/1,
ttyskip/1,
rename/2,
write_depth/2], ['$default_expand'/1,
'$extend_file_search_path'/1,
'$set_default_expand'/1]).
:- use_system_module( '$_boot', ['$system_catch'/4]).
:- use_system_module( '$_errors', ['$do_error'/2]).
/** @defgroup InputOutput Input/Output Predicates
@ingroup builtins
Some of the Input/Output predicates described below will in certain conditions
provide error messages and abort only if the file_errors flag is set.
If this flag is cleared the same predicates will just fail. Details on
setting and clearing this flag are given under 7.7.
@{
*/
/* stream predicates */
/** @defgroup IO_Sockets YAP Old Style Socket and Pipe Interface
@{
Autoload the socket/pipe library
*/
/** @pred socket(+ _DOMAIN_,- _SOCKET_)
Call socket/4 with _TYPE_ bound to `SOCK_STREAM'` and
_PROTOCOL_ bound to `0`.
*/
/** @pred socket(+ _DOMAIN_,+ _TYPE_,+ _PROTOCOL_,- _SOCKET_)
Corresponds to the BSD system call `socket`. Create a socket for
domain _DOMAIN_ of type _TYPE_ and protocol
_PROTOCOL_. Both _DOMAIN_ and _TYPE_ should be atoms,
whereas _PROTOCOL_ must be an integer.
The new socket object is
accessible through a descriptor bound to the variable _SOCKET_.
The current implementation of YAP accepts socket
domains `AF_INET` and `AF_UNIX`.
Socket types depend on the
underlying operating system, but at least the following types are
supported: `SOCK_STREAM'` and `SOCK_DGRAM'` (untested in 6.3).
*/
/** @pred socket_connect(+ _SOCKET_, + _PORT_, - _STREAM_)
Interface to system call `connect`, used for clients: connect
socket _SOCKET_ to _PORT_. The connection results in the
read/write stream _STREAM_.
Port information depends on the domain:
+ 'AF_UNIX'(+ _FILENAME_)
+ 'AF_FILE'(+ _FILENAME_)
connect to socket at file _FILENAME_.
+ 'AF_INET'(+ _HOST_,+ _PORT_)
Connect to socket at host _HOST_ and port _PORT_.
*/
/** @pred open_pipe_streams(Read, Write)
Autoload old pipe access interface
*/
%! @}
/** @pred exists(+ _F_)
Checks if file _F_ exists in the current directory.
*/
exists(F) :-
absolute_file_name(F, _, [file_errors(fail),access(exist),expand(true)]).
%! @addtogroup ReadTerm
% @{
/* Term IO */
%! @}
%! @addtogroup Write
% @{
/* meaning of flags for '$write' is
1 quote illegal atoms
2 ignore operator declarations
4 output '$VAR'(N) terms as A, B, C, ...
8 use portray(_)
flags are defined in yapio.h
*/
/** @pred display(+ _T_)
Displays term _T_ on the current output stream. All Prolog terms are
written in standard parenthesized prefix notation.
*/
display(T) :-
current_output(Out),
write_term(Out, T, [ignore_ops(true)]).
/** @pred display(+ _S_, _T_)
Like display/1, but using stream _S_ to display the term.
*/
display(Stream, T) :-
write_term(Stream, T, [ignore_ops(true)]).
/* interface to user portray */
'$portray'(T) :-
\+ '$undefined'(portray(_),user),
'$system_catch'(call(portray(T)),user,Error,user:'$Error'(Error)), !,
set_value('$portray',true), fail.
'$portray'(_) :- set_value('$portray',false), fail.
%! @}
%! @addtogroup Format
% @{
/** @pred format(+ _T_)
Print formatted output to the current output stream.
*/
format(T) :-
format(T, []).
%! @}
%! @addtogroup CharsIO
% @{
/* character I/O */
/** @pred ttyget(- _C_)
The same as `get(C)`, but from stream user_input.
*/
ttyget(N) :- get(user_input,N).
/** @pred ttyget0(- _C_)
The same as `get0(C)`, but from stream user_input.
*/
ttyget0(N) :- get0(user_input,N).
/** @pred ttyskip(- _C_)
Like skip/1, but always using stream user_input.
stream.
*/
ttyskip(N) :- N1 is N, '$skip'(user_input,N1).
/** @pred ttyput(+ _N_)
As `put(N)` but always to user_output.
*/
ttyput(N) :- N1 is N, put(user_output,N1).
/** @pred ttynl
Outputs a new line to stream user_output.
*/
ttynl :- nl(user_output).
%! @}
%! @addtogroup StreamM
% @{
/** @pred current_line_number(- _LineNumber_)
Unify _LineNumber_ with the line number for the current output stream.
*/
current_line_number(N) :-
current_input(Stream),
line_count(Stream, N).
/** @pred current_line_number(+ _Stream_,- _LineNumber_)
Unify _LineNumber_ with the line number for _Stream_.
*/
current_line_number(Stream,N) :-
line_count(Stream, N).
/** @pred stream_position(+ _Stream_,- _StreamPosition_)
Unify _StreamPosition_ with the packaged information of position on
current stream _Stream_. Use stream_position_data/3 to
retrieve information on character or line count.
*/
stream_position(Stream, Position) :-
stream_property(Stream, position(Position)).
/** @pred stream_position(+ _Stream_,- _StreamPosition_, +_NewPosition_)
Unify _StreamPosition_ with the packaged information of position on
current stream _Stream_ an then moves to position _NewPosition_.
*/
stream_position(Stream, Position, NewPosition) :-
stream_property(Stream, position(Position)),
set_stream_position(Stream, NewPosition).
/** @pred at_end_of_line
Tests whether the next character in the current input stream is a line break character.
*/
at_end_of_line :-
current_input(S),
at_end_of_line(S).
/** @pred at_end_of_line( +Stream )
Tests whether the next character in the stream is a line break character.
*/
at_end_of_line(S) :-
stream_property(S, end_of_stream(past)), !.
at_end_of_line(S) :-
peek_code(S,N), ( N = 10 -> true ; N = -1).
/** @pred current_char_conversion(? _IN_,? _OUT_) is iso
If _IN_ is unbound give all current character
translations. Otherwise, give the translation for _IN_, if one
exists.
*/
current_char_conversion(X,Y) :-
var(X), !,
'$all_char_conversions'(List),
'$fetch_char_conversion'(List,X,Y).
current_char_conversion(X,Y) :-
'$current_char_conversion'(X,Y).
'$fetch_char_conversion'([X,Y|_],X,Y).
'$fetch_char_conversion'([_,_|List],X,Y) :-
'$fetch_char_conversion'(List,X,Y).
split_path_file(File, Path, Name) :-
file_directory_name(File, Path),
file_base_name(File, Name).
/** @pred current_stream( _F_, _M_, _S_)
Defines the relation: The stream _S_ is opened on the file _F_
in mode _M_. It might be used to obtain all open streams (by
backtracking) or to access the stream for a file _F_ in mode
_M_, or to find properties for a stream _S_. Notice that some
streams might not be associated to a file: in this case YAP tries to
return the file number. If that is not available, YAP unifies _F_
with _S_.
*/
current_stream(File, Mode, Stream) :-
stream_property(Stream, mode(Mode)),
'$stream_name'(Stream, File).
'$stream_name'(Stream, File) :-
stream_property(Stream, file_name(File)), !.
'$stream_name'(Stream, file_no(File)) :-
stream_property(Stream, file_no(File)), !.
'$stream_name'(Stream, Stream).
'$extend_file_search_path'(P) :-
atom_codes(P,S),
'$env_separator'(ES),
'$split_for_path'(S,0'=,ES,Paths), %'
'$add_file_search_paths'(Paths).
'$split_for_path'([], _, _, []).
'$split_for_path'(S, S1, S2, [A1=A2|R]) :-
'$fetch_first_path'(S, S1, A1, SR1),
'$fetch_second_path'(SR1, S2, A2, SR),
'$split_for_path'(SR, S1, S2, R) .
'$fetch_first_path'([S1|SR],S1,[],SR) :- !.
'$fetch_first_path'([C|S],S1,[C|F],SR) :-
'$fetch_first_path'(S,S1,F,SR).
'$fetch_second_path'([],_,[],[]).
'$fetch_second_path'([S1|SR],S1,[],SR) :- !.
'$fetch_second_path'([C|S],S1,[C|A2],SR) :-
'$fetch_second_path'(S,S1,A2,SR).
'$add_file_search_paths'([]).
'$add_file_search_paths'([NS=DS|Paths]) :-
atom_codes(N,NS),
atom_codes(D,DS),
assert(user:file_search_path(N,D)),
'$add_file_search_paths'(Paths).
'$format@'(Goal,Out) :-
with_output_to(codes(Out), Goal).
sformat(String, Form, Args) :-
format(codes(String, []), Form, Args).
/** @pred stream_position_data(+ _Field_,+ _StreamPosition_,- _Info_)
Extract values from stream position objects.
'$stream_position' is of the format '$stream_position'(Byte, Char,
Line, LinePos). Given the packaged stream position term
_StreamPosition_, unify _Info_ with _Field_ `line_count`,
`byte_count`, or `char_count`.
*/
stream_position_data(Prop, Term, Value) :-
nonvar(Prop), !,
( '$stream_position_field'(Prop, Pos)
-> arg(Pos, Term, Value)
; '$do_error'(domain_error(stream_position_data), Prop)
).
stream_position_data(Prop, Term, Value) :-
'$stream_position_field'(Prop, Pos),
arg(Pos, Term, Value).
'$stream_position_field'(char_count, 1).
'$stream_position_field'(line_count, 2).
'$stream_position_field'(line_position, 3).
'$stream_position_field'(byte_count, 4).
'$set_encoding'(Enc) :-
set_stream(loop_stream, encoding(Enc)).
%! @}
'$codes_to_chars'(String0, String, String0) :- String0 == String, !.
'$codes_to_chars'(String0, [Code|String], [Char|Chars]) :-
atom_codes(Char, [Code]),
'$codes_to_chars'(String0, String, Chars).
/** @pred file_exists(+ _File__)
The atom _File_ corresponds to an existing file or directory.
*/
file_exists(IFile) :-
absolute_file_name(IFile, _File, [expand(true), solutions(first), access(exist)]).
/** @pred rename(+F , +G)
Renames the single file _F_ to _G_.
*/
rename(IFile, OFile) :-
absolute_file_name(IFile, IF, [access(read),expand(true)]),
absolute_file_name(OFile, OF, [expand(true)]),
'$rename'(IF, OF).
/** @pred access_file(+F , +G)
Verify whether file F respects property _G_. The file is processed
with absolute_file_name.
*/
access_file(IFile, Access) :-
absolute_file_name(IFile, _IF, [access(Access),expand(true)]).
/**
@}
*/