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yap-6.3/library/charsio.yap
Vitor Santos Costa 74222843e5 docs
2018-05-08 23:42:02 +01:00

231 lines
6.5 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: charsio.yap *
* Last rev: 5/12/99 *
* mods: *
* comments: I/O on character strings *
* *
*************************************************************************/
/**
* @file charsio.yap
* @author VITOR SANTOS COSTA <vsc@VITORs-MBP.lan>
* @date Tue Nov 17 01:17:33 2015
*
* @brief Several operations on text.
* @{
*
*/
:- module(charsio, [
format_to_chars/3,
format_to_chars/4,
write_to_chars/3,
write_to_chars/2,
atom_to_chars/3,
atom_to_chars/2,
number_to_chars/3,
number_to_chars/2,
read_from_chars/2,
open_chars_stream/2,
with_output_to_chars/2,
with_output_to_chars/3,
with_output_to_chars/4,
term_to_atom/2
]).
/** @defgroup charsio Operations on Sequences of Codes.
@ingroup library
Term to sequence of codes conversion, mostly replaced by engine code.
You can use the following directive to load the files.
~~~~~~~
:- use_module(library(avl)).
~~~~~~~
It includes the following predicates:
- atom_to_chars/2
- atom_to_chars/3
- format_to_chars/3
- format_to_chars/4
- number_to_chars/2
- number_to_chars/3
- open_chars_stream/2
- read_from_chars/2
- term_to_atom/2
- with_output_to_chars/2
- with_output_to_chars/3
- with_output_to_chars/4
- write_to_chars/2
- write_to_chars/3
*/
:- meta_predicate(with_output_to_chars(0,?)).
:- meta_predicate(with_output_to_chars(0,-,?)).
:- meta_predicate(with_output_to_chars(0,-,?,?)).
/** @pred format_to_chars(+ _Form_, + _Args_, - _Result_)
Execute the built-in procedure format/2 with form _Form_ and
arguments _Args_ outputting the result to the string of character
codes _Result_.
*/
format_to_chars(Format, Args, Codes) :-
format(codes(Codes), Format, Args).
/** @pred format_to_chars(+ _Form_, + _Args_, - _Result_, - _Result0_)
Execute the built-in procedure format/2 with form _Form_ and
arguments _Args_ outputting the result to the difference list of
character codes _Result-Result0_.
*/
format_to_chars(Format, Args, OUT, L0) :-
format(codes(OUT, L0), Format, Args).
/** @pred write_to_chars(+ _Term_, - _Result_)
Execute the built-in procedure write/1 with argument _Term_
outputting the result to the string of character codes _Result_.
*/
write_to_chars(Term, Codes) :-
format(codes(Codes), '~w', [Term]).
/** @pred write_to_chars(+ _Term_, - _Result0_, - _Result_)
Execute the built-in procedure write/1 with argument _Term_
outputting the result to the difference list of character codes
_Result-Result0_.
*/
write_to_chars(Term, Out, Tail) :-
format(codes(Out,Tail),'~w',[Term]).
/** @pred atom_to_chars(+ _Atom_, - _Result_)
Convert the atom _Atom_ to the string of character codes
_Result_.
*/
atom_to_chars(Atom, OUT) :-
atom_codes(Atom, OUT).
/** @pred atom_to_chars(+ _Atom_, - _Result0_, - _Result_)
Convert the atom _Atom_ to the difference list of character codes
_Result-Result0_.
*/
atom_to_chars(Atom, L0, OUT) :-
format(codes(L0, OUT), '~a', [Atom]).
/** @pred number_to_chars(+ _Number_, - _Result_)
Convert the number _Number_ to the string of character codes
_Result_.
*/
number_to_chars(Number, OUT) :-
number_codes(Number, OUT).
/** @pred number_to_chars(+ _Number_, - _Result0_, - _Result_)
Convert the atom _Number_ to the difference list of character codes
_Result-Result0_.
*/
number_to_chars(Number, L0, OUT) :-
var(Number), !,
throw(error(instantiation_error,number_to_chars(Number, L0, OUT))).
number_to_chars(Number, L0, OUT) :-
number(Number), !,
format(codes(L0, OUT), '~w', [Number]).
number_to_chars(Number, L0, OUT) :-
throw(error(type_error(number,Number),number_to_chars(Number, L0, OUT))).
/** @pred open_chars_stream(+ _Chars_, - _Stream_)
Open the list of character codes _Chars_ as a stream _Stream_.
*/
open_chars_stream(Codes, Stream) :-
open_chars_stream(Codes, Stream, '').
open_chars_stream(Codes, Stream, Postfix) :-
predicate_property(memory_file:open_memory_file(_,_,_),_), !,
memory_file:new_memory_file(MF),
memory_file:open_memory_file(MF, write, Out),
format(Out, '~s~w', [Codes, Postfix]),
close(Out),
memory_file:open_memory_file(MF, read, Stream,
[ free_on_close(true)
]).
open_chars_stream(Codes, Stream, Postfix) :-
ensure_loaded(library(memfile)),
open_chars_stream(Codes, Stream, Postfix).
/** @pred with_output_to_chars(? _Goal_, - _Chars_)
Execute goal _Goal_ such that its standard output will be sent to a
memory buffer. After successful execution the contents of the memory
buffer will be converted to the list of character codes _Chars_.
*/
with_output_to_chars(Goal, Codes) :-
with_output_to(codes(Codes), Goal).
/** @pred with_output_to_chars(? _Goal_, ? _Chars0_, - _Chars_)
Execute goal _Goal_ such that its standard output will be sent to a
memory buffer. After successful execution the contents of the memory
buffer will be converted to the difference list of character codes
_Chars-Chars0_.
*/
with_output_to_chars(Goal, Codes, L0) :-
with_output_to(codes(Codes, L0), Goal).
%% with_output_to_chars(:Goal, -Stream, -Codes, ?Tail) is det.
%
% As with_output_to_chars/2, but Stream is unified with the
% temporary stream.
/** @pred with_output_to_chars(? _Goal_, - _Stream_, ? _Chars0_, - _Chars_)
Execute goal _Goal_ such that its standard output will be sent to a
memory buffer. After successful execution the contents of the memory
buffer will be converted to the difference list of character codes
_Chars-Chars0_ and _Stream_ receives the stream corresponding to
the memory buffer.
*/
with_output_to_chars(Goal, Stream, Codes, Tail) :-
with_output_to(codes(Codes, Tail), with_stream(Stream, Goal)).
with_stream(Stream, Goal) :-
current_output(Stream),
call(Goal).
/** @pred read_from_chars( + Chars, - Term)
Parse the list of character codes _Chars_ and return the result in
the term _Term_. The character codes to be read must terminate with
a dot character such that either (i) the dot character is followed by
blank characters; or (ii) the dot character is the last character in the
string.
@note The SWI-Prolog version does not require Codes to end
in a full-stop.
*/
read_from_chars("", end_of_file) :- !.
read_from_chars(List, Term) :-
atom_to_term(List, Term, _).
/**
@}
*/