This library wraps the BSD libedit command line editor. The binding
provides a high level API to enable command line editing on the Prolog
user streams and low level predicates to apply the library on other
streams and program the library.
- el_wrap is det
- Enable using editline on the standard user streams if
is connected to a terminal. This is the high level predicate used
for most purposes. The remainder of the library interface deals with
low level predicates that allows for applying and programming
libedit in non-standard situations.
The library is registered with ProgName set to
- el_wrap(+ProgName:atom, +In:stream, +Out:stream, +Error:stream) is det
- Enable editline on the stream-triple <In,Out,Error>. From this
moment on In is a handle to the command line editor.
|ProgName||- is the name of the invoking program, used when reading
editrc(5) file to determine which settings to use.
- el_setup(+In:stream) is nondet[multifile]
- This hooks is called as
forall(el_setup(Input), true) after the
input stream has been wrapped, the default Prolog commands have been
added and the default user setup file has been sourced using
el_source/2. It can be used to define and bind additional commands.
- el_wrapped(+In:stream) is semidet
- True if In is a stream wrapped by el_wrap/3.
- el_unwrap(+In:stream) is det
- Remove the libedit wrapper for In and the related output and error
- - The wrapper creates
FILE* handles that cannot be closed and
thus wrapping and unwrapping implies a (modest) memory leak.
- el_source(+In:stream, +File) is det
- Initialise editline by reading the contents of File. If File is
- el_bind(+In:stream, +Args) is det
- Invoke the libedit
bind command with the given arguments. The
example below lists the current key bindings.
?- el_bind(user_input, ['-a']).
The predicate el_bind/2 is typically used to bind commands defined
using el_addfn/4. Note that the C proxy function has only the last
character of the command as context to find the Prolog binding. This
implies we cannot both bind e.g., "^[?" *and "?" to a Prolog
- See also
editrc(5) for more information.
- el_addfn(+Input:stream, +Command, +Help, :Goal) is det
- Add a new command to the command line editor associated with Input.
Command is the name of the command, Help is the help string printed
bind -a (see el_bind/2) and Goal is called of the
associated key-binding is activated. Goal is called as
call(:Goal, +Input, +Char, -Continue)
where Input is the input stream providing access to the editor, Char
the activating character and Continue must be instantated with one
of the known continuation codes as defined by libedit:
fatal. In addition, the following Continue
code is provided.
- electric(Move, TimeOut, Continue)
- Show electric caret at Move positions to the left of the normal
cursor positions for the given TimeOut. Continue as defined by
the Continue value.
The registered Goal typically used el_line/2 to fetch the input line
and el_cursor/2, el_insertstr/2 and/or el_deletestr/2 to manipulate
the input line.
Normally el_bind/2 is used to associate the defined command with a
- See also
EL_ADDFN for details.
- el_line(+Input:stream, -Line) is det
- Fetch the currently buffered input line. Line is a term
After), where Before is a string holding the text before the
cursor and After is a string holding the text after the cursor.
- el_cursor(+Input:stream, +Move:integer) is det
- Move the cursor Move character forwards (positive) or backwards
- el_insertstr(+Input:stream, +Text) is det
- Insert Text at the cursor.
- el_deletestr(+Input:stream, +Count) is det
- Delete Count characters before the cursor.
- el_history(+In:stream, ?Action) is det
- Perform a generic action on the history. This provides an incomplete
history() from libedit. Supported actions are:
- Clear the history.
- Set size of history to size elements.
- Set flag that adjacent identical event strings should not be
entered into the history.
- el_history_events(+In:stream, -Events:list(pair)) is det
- Unify Events with a list of pairs of the form
Num is the event number and String is the associated string
without terminating newline.
- el_add_history(+In:stream, +Line:text) is det
- Add a line to the command line history.
- el_read_history(+In:stream, +File:file) is det
- Read the history saved using el_write_history/2.
- el_write_history(+In:stream, +File:file) is det
- Save editline history to File. The history may be reloaded using