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\libdoc{readutil}{Reading lines, streams and files}
This library contains primitives to read lines, files, multiple terms,
etc.
\begin{description}
\predicate{read_line_to_codes}{2}{+Stream, -Codes}
Read the next line of input from \arg{Stream} and unify the result with
\arg{Codes} \emph{after} the line has been read. A line is ended by
a newline character or end-of-file. Unlike read_line_to_codes/3, this
predicate removes trailing newline character.
\predicate{read_line_to_codes}{3}{+Stream, -Codes, ?Tail}
Diference-list version to read an input line to a list of character
codes. Reading stops at the newline or end-of-file character, but
unlike read_line_to_codes/2, the newline is retained in the output.
This predicate is especially useful for readine a block of lines
upto some delimiter. The following example reads an HTTP header
ended by a blank line:
\begin{code}
read_header_data(Stream, Header) :-
read_line_to_codes(Stream, Header, Tail),
read_header_data(Header, Stream, Tail).
read_header_data("\r\n", _, _) :- !.
read_header_data("\n", _, _) :- !.
read_header_data("", _, _) :- !.
read_header_data(_, Stream, Tail) :-
read_line_to_codes(Stream, Tail, NewTail),
read_header_data(Tail, Stream, NewTail).
\end{code}
\predicate{read_stream_to_codes}{2}{+Stream, -Codes}
Read all input until end-of-file and unify the result to \arg{Codes}.
\predicate{read_stream_to_codes}{3}{+Stream, -Codes, ?Tail}
Difference-list version of read_stream_to_codes/2.
\predicate{read_file_to_codes}{3}{+Spec, -Codes, +Options}
Read a file to a list of character codes. \arg{Spec} is a
file-specification for absolute_file_name/3. \arg{Codes} is the
resulting code-list. \arg{Options} is a list of options for
absolute_file_name/3 and open/4. In addition, the option
\term{tail}{Tail} is defined, forming a difference-list.
\predicate{read_file_to_terms}{3}{+Spec, -Terms, +Options}
Read a file to a list of character codes. \arg{Spec} is a
file-specification for absolute_file_name/3. \arg{Terms} is the
resulting list of Prolog terms. \arg{Options} is a list of options for
absolute_file_name/3 and open/4. In addition, the option
\term{tail}{Tail} is defined, forming a difference-list.
\end{description}
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