ELF>@ @@ö /** Pure I/O. Our goal is to encourage the use of definite clause grammars (DCGs) for describing strings. The predicates `phrase_from_file/[2,3]`, `phrase_to_file/[2,3]` and `phrase_to_stream/2` let us apply DCGs transparently to files and streams, and therefore decouple side-effects from declarative descriptions. */ :- module(pio, [phrase_from_file/2, phrase_from_file/3, phrase_to_file/2, phrase_to_file/3, phrase_to_stream/2 ]). :- use_module(library(dcgs)). :- use_module(library(error)). :- use_module(library(lists), [member/2, maplist/2]). :- use_module(library(charsio), [get_n_chars/3]). :- meta_predicate(phrase_from_file(2, ?)). :- meta_predicate(phrase_from_file(2, ?, ?)). :- meta_predicate(phrase_to_file(2, ?)). :- meta_predicate(phrase_to_file(2, ?, ?)). :- meta_predicate(phrase_to_stream(2, ?)). phrase_from_file(NT, File) :- phrase_from_file(NT, File, []). phrase_from_file(NT, File, Options) :- ( var(File) -> instantiation_error(phrase_from_file/3) ; must_be(list, Options), ( member(Var, Options), var(Var) -> instantiation_error(phrase_from_file/3) ; member(type(Type), Options) -> must_be(atom, Type), member(Type, [text,binary]) ; Type = text ), setup_call_cleanup( open(File, read, Stream, [mmap(Ms)|Options]), (copy_term(NT, NT2), NT2=NT, phrase(NT2, Ms, [])), close(Stream) ) ). %% phrase_to_stream(+GRBody, +Stream) % % Emit the list of characters described by the grammar rule body % GRBody to Stream. % % An ideal implementation of `phrase_to_stream/2` writes each % character as soon as it becomes known and no choice-points remain, % and thus avoids the manifestation of the entire string in memory. % See [#691](https://github.com/mthom/scryer-prolog/issues/691) for % more information. % % The current preliminary implementation is provided so that Prolog % programmers can already get used to describing output with DCGs, % and then writing it to a file when necessary. This simple % implementation suffices as long as the entire contents can be % represented in memory, and thus covers a large number of use cases. phrase_to_stream(GRBody, Stream) :- phrase(GRBody, Cs), must_be(chars, Cs), ( stream_property(Stream, type(binary)) -> ( '$first_non_octet'(Cs, N) -> domain_error(octet_character, N, phrase_to_stream/2) ; true ) ; true ), % we use a specialised internal predicate that uses only a % single "write" operation for efficiency. It is equivalent to % maplist(put_char(Stream), Cs). It also works for binary streams. '$put_chars'(Stream, Cs). phrase_to_file(GRBody, File) :- phrase_to_file(GRBody, File, []). phrase_to_file(GRBody, File, Options) :- setup_call_cleanup( open(File, write, Stream, Options), phrase_to_stream(GRBody, Stream), close(Stream) ). GCC: (OpenIndiana 14.3.0-oi-0) 14.3.0ñÿ ö pio.clibrary_pio_pl_lenlibrary_pio_pl.symtab.strtab.shstrtab.text.data.bss.comment@!@ 'V ,0V '€ `  à ) 5