.\"	$OpenBSD: editline.3,v 1.20 2004/04/14 22:00:35 jfb Exp $
.\"	$NetBSD: editline.3,v 1.42 2003/11/04 13:22:19 christos Exp $
.\"
.\" Copyright (c) 1997-1999 The NetBSD Foundation, Inc.
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.\" This file was contributed to The NetBSD Foundation by Luke Mewburn.
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.Dd October 17, 2003
.Os
.Dt EDITLINE 3
.Sh NAME
.Nm editline ,
.Nm el_init ,
.Nm el_end ,
.Nm el_reset ,
.Nm el_gets ,
.Nm el_getc ,
.Nm el_push ,
.Nm el_parse ,
.Nm el_set ,
.Nm el_source ,
.Nm el_resize ,
.Nm el_line ,
.Nm el_insertstr ,
.Nm el_deletestr ,
.Nm history_init ,
.Nm history_end ,
.Nm history
.Nd line editor and history functions
.Sh SYNOPSIS
.Fd #include <histedit.h>
.Ft EditLine *
.Fn el_init "const char *prog" "FILE *fin" "FILE *fout" "FILE *ferr"
.Ft void
.Fn el_end "EditLine *e"
.Ft void
.Fn el_reset "EditLine *e"
.Ft const char *
.Fn el_gets "EditLine *e" "int *count"
.Ft int
.Fn el_getc "EditLine *e" "char *ch"
.Ft void
.Fn el_push "EditLine *e" "const char *str"
.Ft int
.Fn el_parse "EditLine *e" "int argc" "const char *argv[]"
.Ft int
.Fn el_set "EditLine *e" "int op" "..."
.Ft int
.Fn el_get "EditLine *e" "int op" "void *result"
.Ft int
.Fn el_source "EditLine *e" "const char *file"
.Ft void
.Fn el_resize "EditLine *e"
.Ft const LineInfo *
.Fn el_line "EditLine *e"
.Ft int
.Fn el_insertstr "EditLine *e" "const char *str"
.Ft void
.Fn el_deletestr "EditLine *e" "int count"
.Ft History *
.Fn history_init
.Ft void
.Fn history_end "History *h"
.Ft int
.Fn history "History *h" "HistEvent *ev" "int op" "..."
.Sh DESCRIPTION
The
.Nm
library provides generic line editing and history functions,
similar to those found in
.Xr sh 1 .
.Pp
These functions are available in the
.Nm libedit
library (which needs the
.Nm libcurses
library).
Programs should be linked with
.Fl ledit lcurses .
.Sh LINE EDITING FUNCTIONS
The line editing functions use a common data structure,
.Fa EditLine ,
which is created by
.Fn el_init
and freed by
.Fn el_end .
.Pp
The following functions are available:
.Bl -tag -width 4n
.It Fn el_init
Initialise the line editor, and return a data structure
to be used by all other line editing functions.
.Fa prog
is the name of the invoking program, used when reading the
.Xr editrc 5
file to determine which settings to use.
.Fa fin ,
.Fa fout
and
.Fa ferr
are the input, output, and error streams (respectively) to use.
In this documentation, references to
.Dq the tty
are actually to this input/output stream combination.
.It Fn el_end
Clean up and finish with
.Fa e ,
assumed to have been created with
.Fn el_init .
.It Fn el_reset
Reset the tty and the parser.
This should be called after an error which may have upset the tty's
state.
.It Fn el_gets
Read a line from the tty.
.Fa count
is modified to contain the number of characters read.
Returns the line read if successful, or
.Dv NULL
if no characters were read or if an error occurred.
.It Fn el_getc
Read a character from the tty.
.Fa ch
is modified to contain the character read.
Returns the number of characters read if successful, \-1 otherwise.
.It Fn el_push
Pushes
.Fa str
back onto the input stream.
This is used by the macro expansion mechanism.
Refer to the description of
.Ic bind
.Fl s
in
.Xr editrc 5
for more information.
.It Fn el_parse
Parses the
.Fa argv
array (which is
.Fa argc
elements in size)
to execute builtin
.Nm
commands.
If the command is prefixed with
.Dq prog :
then
.Fn el_parse
will only execute the command if
.Dq prog
matches the
.Fa prog
argument supplied to
.Fn el_init .
The return value is
\-1 if the command is unknown,
0 if there was no error or
.Dq prog
didn't match, or
1 if the command returned an error.
Refer to
.Xr editrc 5
for more information.
.It Fn el_set
Set
.Nm
parameters.
.Fa op
determines which parameter to set, and each operation has its
own parameter list.
.Pp
The following values for
.Fa op
are supported, along with the required argument list:
.Bl -tag -width 4n
.It Dv EL_PROMPT , Fa "char *(*f)(EditLine *)"
Define prompt printing function as
.Fa f ,
which is to return a string that contains the prompt.
.It Dv EL_RPROMPT , Fa "char *(*f)(EditLine *)"
Define right side prompt printing function as
.Fa f ,
which is to return a string that contains the prompt.
.It Dv EL_TERMINAL , Fa "const char *type"
Define terminal type of the tty to be
.Fa type ,
or to
.Ev TERM
if
.Fa type
is
.Dv NULL .
.It Dv EL_EDITOR , Fa "const char *mode"
Set editing mode to
.Fa mode ,
which must be one of
.Dq emacs
or
.Dq vi .
.It Dv EL_SIGNAL , Fa "int flag"
If
.Fa flag
is non-zero,
.Nm
will install its own signal handler for the following signals when
reading command input:
.Dv SIGCONT ,
.Dv SIGHUP ,
.Dv SIGINT ,
.Dv SIGQUIT ,
.Dv SIGSTOP ,
.Dv SIGTERM ,
.Dv SIGTSTP ,
and
.Dv SIGWINCH .
Otherwise, the current signal handlers will be used.
.It Dv EL_BIND , Xo
.Fa "const char *" ,
.Fa "..." ,
.Dv NULL
.Xc
Perform the
.Ic bind
builtin command.
Refer to
.Xr editrc 5
for more information.
.It Dv EL_ECHOTC , Xo
.Fa "const char *" ,
.Fa "..." ,
.Dv NULL
.Xc
Perform the
.Ic echotc
builtin command.
Refer to
.Xr editrc 5
for more information.
.It Dv EL_SETTC , Xo
.Fa "const char *" ,
.Fa "..." ,
.Dv NULL
.Xc
Perform the
.Ic settc
builtin command.
Refer to
.Xr editrc 5
for more information.
.It Dv EL_SETTY , Xo
.Fa "const char *" ,
.Fa "..." ,
.Dv NULL
.Xc
Perform the
.Ic setty
builtin command.
Refer to
.Xr editrc 5
for more information.
.It Dv EL_TELLTC , Xo
.Fa "const char *" ,
.Fa "..." ,
.Dv NULL
.Xc
Perform the
.Ic telltc
builtin command.
Refer to
.Xr editrc 5
for more information.
.It Dv EL_ADDFN , Xo
.Fa "const char *name" ,
.Fa "const char *help" ,
.Fa "unsigned char (*func)(EditLine *e, int ch)"
.Xc
Add a user defined function,
.Fn func ,
referred to as
.Fa name
which is invoked when a key which is bound to
.Fa name
is entered.
.Fa help
is a description of
.Fa name .
At invocation time,
.Fa ch
is the key which caused the invocation.
The return value of
.Fn func
should be one of:
.Bl -tag -width "CC_REDISPLAY"
.It Dv CC_NORM
Add a normal character.
.It Dv CC_NEWLINE
End of line was entered.
.It Dv CC_EOF
EOF was entered.
.It Dv CC_ARGHACK
Expecting further command input as arguments, do nothing visually.
.It Dv CC_REFRESH
Refresh display.
.It Dv CC_REFRESH_BEEP
Refresh display, and beep.
.It Dv CC_CURSOR
Cursor moved, so update and perform
.Dv CC_REFRESH .
.It Dv CC_REDISPLAY
Redisplay entire input line.
This is useful if a key binding outputs extra information.
.It Dv CC_ERROR
An error occurred.
Beep, and flush tty.
.It Dv CC_FATAL
Fatal error, reset tty to known state.
.El
.It Dv EL_HIST , Xo
.Fa "History *(*func)(History *, int op, ...)" ,
.Fa "const char *ptr"
.Xc
Defines which history function to use, which is usually
.Fn history .
.Fa ptr
should be the value returned by
.Fn history_init .
.It Dv EL_EDITMODE , Fa "int flag"
If
.Fa flag
is non-zero,
editing is enabled (the default).
Note that this is only an indication, and does not
affect the operation of
.Nm .
At this time, it is the caller's responsibility to
check this
(using
.Fn el_get )
to determine if editing should be enabled or not.
.It Dv EL_GETCFN , Fa "int (*f)(EditLine *, char *c)"
Define the character reading function as
.Fa f ,
which is to return the number of characters read and store them in
.Fa c .
This function is called internally by
.Fn el_gets
and
.Fn el_getc .
The builtin function can be set or restored with the special function
name ``EL_BUILTIN_GETCFN''.
.It Dv EL_CLIENTDATA , Fa "void *data"
Register
.Fa data
to be associated with this EditLine structure.
It can be retrieved with the corresponding
.Fn el_get
call.
.El
.It Fn el_get
Get
.Nm
parameters.
.Fa op
determines which parameter to retrieve into
.Fa result .
Returns 0 if successful, \-1 otherwise.
.Pp
The following values for
.Fa op
are supported, along with actual type of
.Fa result :
.Bl -tag -width 4n
.It Dv EL_PROMPT , Fa "char *(*f)(EditLine *)"
Return a pointer to the function that displays the prompt.
.It Dv EL_RPROMPT , Fa "char *(*f)(EditLine *)"
Return a pointer to the function that displays the rightside prompt.
.It Dv EL_EDITOR , Fa "const char *"
Return the name of the editor, which will be one of
.Dq emacs
or
.Dq vi .
.It Dv EL_SIGNAL , Fa "int *"
Return non-zero if
.Nm
has installed private signal handlers (see
.Fn el_get
above).
.It Dv EL_EDITMODE, Fa "int *"
Return non-zero if editing is enabled.
.It Dv EL_GETCFN, Fa "int (**f)(EditLine *, char *)"
Return a pointer to the function that read characters, which is equal to
``EL_BUILTIN_GETCFN'' in the case of the default builtin function.
.It Dv EL_CLIENTDATA , Fa "void **data"
Retrieve
.Fa data
previously registered with the corresponding
.Fn el_set
call.
.It Dv EL_UNBUFFERED, Fa "int"
Sets or clears unbuffered mode.
In this mode,
.Fn el_gets
will return immediately after processing a single character.
.It Dv EL_PREP_TERM, Fa "int"
Sets or clears terminal editing mode.
.El
.It Fn el_source
Initialise
.Nm
by reading the contents of
.Fa file .
.Fn el_parse
is called for each line in
.Fa file .
If
.Fa file
is
.Dv NULL ,
try
.Pa $PWD/.editrc
then
.Pa $HOME/.editrc .
Refer to
.Xr editrc 5
for details on the format of
.Fa file .
.It Fn el_resize
Must be called if the terminal size changes.
If
.Dv EL_SIGNAL
has been set with
.Fn el_set ,
then this is done automatically.
Otherwise, it's the responsibility of the application to call
.Fn el_resize
on the appropriate occasions.
.It Fn el_line
Return the editing information for the current line in a
.Fa LineInfo
structure, which is defined as follows:
.Bd -literal
typedef struct lineinfo {
    const char *buffer;    /* address of buffer */
    const char *cursor;    /* address of cursor */
    const char *lastchar;  /* address of last character */
} LineInfo;
.Ed
.It Fn el_insertstr
Insert
.Fa str
into the line at the cursor.
Returns \-1 if
.Fa str
is empty or won't fit, and 0 otherwise.
.It Fn el_deletestr
Delete
.Fa num
characters before the cursor.
.El
.Sh HISTORY LIST FUNCTIONS
The history functions use a common data structure,
.Fa History ,
which is created by
.Fn history_init
and freed by
.Fn history_end .
.Pp
The following functions are available:
.Bl -tag -width 4n
.It Fn history_init
Initialise the history list, and return a data structure
to be used by all other history list functions.
.It Fn history_end
Clean up and finish with
.Fa h ,
assumed to have been created with
.Fn history_init .
.It Fn history
Perform operation
.Fa op
on the history list, with optional arguments as needed by the
operation.
.Fa ev
is changed accordingly to operation.
The following values for
.Fa op
are supported, along with the required argument list:
.Bl -tag -width 4n
.It Dv H_SETSIZE , Fa "int size"
Set size of history to
.Fa size
elements.
.It Dv H_GETSIZE
Get number of events currently in history.
.It Dv H_END
Cleans up and finishes with
.Fa h ,
assumed to be created with
.Fn history_init .
.It Dv H_CLEAR
Clear the history.
.It Dv H_FUNC , Xo
.Fa "void *ptr" ,
.Fa "history_gfun_t first" ,
.Fa "history_gfun_t next" ,
.Fa "history_gfun_t last" ,
.Fa "history_gfun_t prev" ,
.Fa "history_gfun_t curr" ,
.Fa "history_sfun_t set" ,
.Fa "history_vfun_t clear" ,
.Fa "history_efun_t enter" ,
.Fa "history_efun_t add"
.Xc
Define functions to perform various history operations.
.Fa ptr
is the argument given to a function when it's invoked.
.It Dv H_FIRST
Return the first element in the history.
.It Dv H_LAST
Return the last element in the history.
.It Dv H_PREV
Return the previous element in the history.
.It Dv H_NEXT
Return the next element in the history.
.It Dv H_CURR
Return the current element in the history.
.It Dv H_SET
Set the cursor to point to the requested element.
.It Dv H_ADD , Fa "const char *str"
Append
.Fa str
to the current element of the history, or perform the
.Dv H_ENTER
operation with argument
.Fa str
if there is no current element.
.It Dv H_APPEND , Fa "const char *str"
Append
.Fa str
to the last new element of the history.
.It Dv H_ENTER , Fa "const char *str"
Add
.Fa str
as a new element to the history, and, if necessary,
removing the oldest entry to keep the list to the created size.
If
.Dv H_SETUNIQUE
has been called with a non-zero argument, the element
will not be entered into the history if its contents match
the ones of the current history element.
If the element is entered
.Fn history
returns 1; if it is ignored as a duplicate returns 0.
Finally
.Fn history
returns \-1 if an error occurred.
.It Dv H_PREV_STR , Fa "const char *str"
Return the closest previous event that starts with
.Fa str .
.It Dv H_NEXT_STR , Fa "const char *str"
Return the closest next event that starts with
.Fa str .
.It Dv H_PREV_EVENT , Fa "int e"
Return the previous event numbered
.Fa e .
.It Dv H_NEXT_EVENT , Fa "int e"
Return the next event numbered
.Fa e .
.It Dv H_LOAD , Fa "const char *file"
Load the history list stored in
.Fa file .
.It Dv H_SAVE , Fa "const char *file"
Save the history list to
.Fa file .
.It Dv H_SETUNIQUE , Fa "int unique"
Set if the adjacent identical event strings should not be entered into
the history.
.It Dv H_GETUNIQUE
Retrieve the current setting if if adjacent elements should be entered into
the history.
.El
.Pp
.Fn history
returns \*(Ge 0 if the operation
.Fa op
succeeds.
Otherwise, \-1 is returned and
.Fa ev
is updated to contain more details about the error.
.El
.\"XXX.Sh EXAMPLES
.\"XXX: provide some examples
.Sh SEE ALSO
.Xr sh 1 ,
.Xr curses 3 ,
.Xr signal 3 ,
.Xr termcap 3 ,
.Xr editrc 5
.Sh HISTORY
The
.Nm
library first appeared in
.Bx 4.4 .
.Dv CC_REDISPLAY
appeared in
.Nx 1.3 .
.Dv CC_REFRESH_BEEP ,
.Dv EL_EDITMODE
and the readline emulation appeared in
.Nx 1.4 .
.Dv EL_RPROMPT
appeared in
.Nx 1.5 .
.Sh AUTHORS
The
.Nm
library was written by Christos Zoulas.
Luke Mewburn wrote this manual and implemented
.Dv CC_REDISPLAY ,
.Dv CC_REFRESH_BEEP ,
.Dv EL_EDITMODE ,
and
.Dv EL_RPROMPT .
Jaromir Dolecek implemented the readline emulation.
.Sh BUGS
The tokenization functions are not publicly defined in
.Aq Pa histedit.h .
.Pp
At this time, it is the responsibility of the caller to
check the result of the
.Dv EL_EDITMODE
operation of
.Fn el_get
(after an
.Fn el_source
or
.Fn el_parse )
to determine if
.Nm
should be used for further input.
I.e.,
.Dv EL_EDITMODE
is purely an indication of the result of the most recent
.Xr editrc 5
.Ic edit
command.