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1993-06-17
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This is Info file ../info/forms, produced by Makeinfo-1.55 from the
input file forms.texinfo.
This file documents forms-mode, a forms based major mode for GNU
Emacs.
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
File: forms, Node: Top, Next: What is in a Forms, Up: (DIR)
Forms mode is an Emacs major mode for working with simple plain-text
databases in a forms-oriented manner. In forms mode, the information in
these files is presented in an Emacs window in a user-defined format,
one record at a time. Forms can be inspected read-only (viewing) or
modified and updated.
Forms mode is not a simple major mode, but requires two files to do
its job: a control file and a data file. The data file holds the actual
data which will be presented. The control file describes how it will be
presented.
* Menu:
* What is in a Forms:: Introduction.
* Data File Format:: How to format the data file.
* Control File Format:: How to control forms mode.
* Forms Format Description::
How to define the forms layout.
* Modifying Forms Contents::
How to modify.
* Forms Mode Commands:: The commands available, and how to use them.
* Key Bindings:: Which keys are bound to what commands.
* Miscellaneous:: Forms mode messages and other remarks.
* Error Messages:: List of error messages forms mode can produce.
* Examples:: Some examples.
* Credits:: Thanks everyone.
* Concept Index:: Index of Concepts
* Variable Index:: Index of Variables.
* Function Index:: Index of Functions.
File: forms, Node: What is in a Forms, Next: Data File Format, Prev: Top, Up: Top
What is in a forms
==================
Let's illustrate forms mode with an example. Suppose you are looking
at your `/etc/passwd' file, and your screen looks as follows:
====== /etc/passwd ======
User : root Uid: 0 Gid: 1
Name : Super User
Home : /
Shell: /bin/sh
As you can see, the familiar fields from the entry for the super user
are all there, but instead of being colon-separated on one single line,
they make up a forms.
The contents of the forms consists of the contents of the fields of
the record (e.g. "root", "0", "1", "Super User") interspersed with
normal text (e.g "User : ", "Uid: ").
You can define yourself how text and fields will be used to make up
the forms.
When you modifiy the contents of the forms, it will be analyzed and
the new contents of the fields of this record will be extracted. It
possible, the file will be updated with the new contents.
File: forms, Node: Data File Format, Next: Control File Format, Prev: What is in a Forms, Up: Top
Data file format
================
Files for use with forms mode are very simple - each record (line)
forms the contents one form. Each record is supposed to consist of a
number of fields. These fields are separated by the value of the string
`forms-field-sep', which is a `TAB' by default.
Fields may contain text which shows up in the forms in multiple
lines. These lines are separated in the field using a PSEUDO-NEWLINE
character which is defined by the value of the string
`forms-multi-line'. Its default value is a Control-K character. If it
is set to `nil' multiple line fields are prohibited.
File: forms, Node: Control File Format, Next: Forms Format Description, Prev: Data File Format, Up: Top
Control file format
===================
The control file serves two purposes.
First, it defines the data file to use, and its properties.
Second, the Emacs buffer it occupies will be used by the forms mode
to display the forms.
The contents of the control file are evaluated using the Emacs
command `eval-current-buffer', hence must contain valid Emacs-lisp
expressions. These expressions must set the following lisp variables
to a suitable value:
`forms-file'
This variable must be set to the name of the data file.
Example:
(setq forms-file "my/data-file")
`forms-format-list'
This variable describes the way the fields of the record are
formatted on the screen. See the next section for details.
`forms-number-of-fields'
This variable holds the number of fields in each record of the data
file.
Example:
(setq forms-number-of-fields 10)
An error will be given if one of the above values has not been set.
Other variables that may be set from the control file are optional.
Most of them have suitable default values.
`forms-field-sep'
This variable may be used to designate the string which separates
the fields in the records of the data file. If not set, it
defaults to a string containing a single `TAB' character.
Example:
(setq forms-field-sep "\t")
`forms-read-only'
If set to a value other than `nil', the data file is treated
read-only. If the data file can not be written into, read-only
mode is enforced. The default value for `forms-read-only' is
derived from the access permissions of the data file.
Example:
(set forms-read-only t)
`forms-multi-line'
This variable may be set to allow multi-line text in fields. It
should be set to a string of one character, which denotes the
pseudo new-line character to be used to separate the text lines.
Its default value is Control-K (octal 013). If set to `nil',
multi-line text fields are prohibited.
It may not be a character contained in `forms-field-sep'.
Example:
(setq forms-multi-line "\C-k")
`forms-forms-scroll'
*Note Forms Mode Commands:: for the description.
`forms-forms-jump'
*Note Forms Mode Commands:: for the description.
`forms-new-record-filter'
The control file may define a function `forms-new-record-filter',
or set `forms-new-record-filter' to such a function. If so, this
function is called when a new record is created to supply default
values for fields.
`forms-modified-record-filter'
The control file may define a function
`forms-modified-record-filter', or set
`forms-modified-record-filter' to such a function. If so, this
function is called when a record is modified, just before writing
the modified record back to the data file.
File: forms, Node: Forms Format Description, Next: Modifying Forms Contents, Prev: Control File Format, Up: Top
The forms format description
============================
The value of the variable `forms-format-list' is used to specify the
format of the forms. It must be a list of formatting elements, each of
which can be a string, number, lisp list or a lisp symbol that
evaluates to one of these. The formatting elements are processed in the
order they appear in the list.
A `string' formatting element is inserted in the forms "as is".
A `number' element selects a field of the record. The contents of
this field are inserted. The first field of the record has number 1
(one).
A `lisp list' specifies a function call. This function is called
every time a record is displayed, and its result, that must be a
string, is inserted in the forms. The function should do nothing but
returning a string. The fields of the record being displayed are
available to this function as the list `forms-fields' and can be
accessed using `(nth 'FIELD NUMBER` forms-fields)'. Fields are
numbered starting from 1 (one).
A `lisp symbol' must evaluate to one of the above possibilities.
If a record does not contain the number of fields as specified in
`forms-number-of-fields', a warning message will be printed. Excess
fields are ignored, missing fields are set to empty.
The control file which shows your `/etc/passwd' file as demonstrated
in the beginning of this document might look as follows:
;; This demo visits /etc/passwd.
(setq forms-file "/etc/passwd")
(setq forms-number-of-fields 7)
(setq forms-read-only t) ; to make sure
(setq forms-field-sep ":")
(setq forms-multi-line nil) ; not allowed
(setq forms-format-list
(list
"====== /etc/passwd ======\n\n"
"User : " 1
" Uid: " 3
" Gid: " 4
"\n\n"
"Name : " 5
"\n\n"
"Home : " 6
"\n\n"
"Shell: " 7
"\n"))
When functions are to be used in `forms-format-list' they must be
quoted to prevent them from being evaluated too early:
(setq forms-format-list
(list
"====== " forms-file " ======\n\n"
"User : " 1
'(make-string 20 ?-)
...
))
Alternatively, instead of quoting the functions, the whole list may
be quoted:
(setq forms-format-list
'(
"====== " forms-file " ======\n\n"
"User : " 1
(make-string 20 ?-)
...
))
Upon startup, the contents of `forms-format-list' are validated. If
errors are encountered, processing is aborted with an error message
which includes a descriptive text. *Note Error Messages::, for a
detailed list of error messages.
File: forms, Node: Modifying Forms Contents, Next: Forms Mode Commands, Prev: Forms Format Description, Up: Top
Modifying The Forms Contents
============================
If a forms is not read-only, it's contents can be modified.
All normal editor commands may be used to change the forms. There is
no distinction between the "fixed" text and the text from the fields of
the records. However, upon completion, the forms is parsed to extract
the new contents of the fields. The "fixed" portions of the forms are
used to delimit the fields, these portions should therefore not be
modified to avoid the risk that the field contents cannot be determined.
Moreover, ambiguous field contents, which can not be discriminated from
"fixed" text, must be avoided.
If the contents of the forms cannot be recognized properly, this is
signaled using a descriptive text. *Note Error Messages::, for more
info. The cursor will indicate the last part of the forms which was
successfully parsed.
If `forms-modified-record-filter' has been set, this function is
called before the new data is written to the data file. The function is
called with one argument: a vector that contains the contents of the
fields of the record. Fields can referenced or modified using the lisp
functions `aref' and `aset'. The first field has number 1 (one). The
function must return the (possibly modified) vector to the calling
environment.
(defun my-modified-record-filter (record)
;; modify second field
(aset record 2 (current-time-string))
record ; return it
)
(setq forms-modified-record-filter 'my-modified-record-filter)
File: forms, Node: Forms Mode Commands, Next: Key Bindings, Prev: Modifying Forms Contents, Up: Top
Forms mode commands
===================
`M-x forms-find-file FILE'
Visits FILE, runs `eval-current-buffer' on it, and puts the buffer
into forms-mode. The first record of the data file will be loaded and
shown.
The modeline will display the major mode `"Forms"' followed by the
minor mode `"View"' if the file is visited read-only. The number of
the current record (N) and the total number of records (T) in the file
is shown in the modeline as `"n/t"'.
For example:
--%%-Emacs: passwd-demo (Forms View 1/54)----All-------
`M-x forms-find-file-other-window FILE'
This command is similar to `forms-find-file', but visits the file in
another window.
If the buffer is not read-only, you may change the buffer to modify
the fields in the record. When the current record is left, e.g. by
switching to another record, the contents of the buffer are parsed
using the specifications in `forms-format-list', and a new record is
constructed which replaces the current record in the data file. Fields
of the record which are not shown in the forms are not modified; they
retain their original contents.
Most forms mode commands are bound to keys, and are accessible with
the conventional `C-c' prefix. In read-only mode this prefix is not
used. *Note Key Bindings::, for the default key bindigs used by forms
mode.
The following commands are available within forms mode.
`forms-next-record'
shows the next record. With a prefix argument, show the n-th next
record.
`forms-prev-record'
shows the previous record. With a prefix argument, show the n-th
previous record.
`forms-jump-record'
jumps to a record by number. A prefix argument is used for the
record number to jump to. If no prefix argument is supplied, a
record number is asked for in the minibuffer.
If an invalid record number is supplied, an error message is
displayed reading the offending record number, and the allowable
range of numbers.
`forms-first-record'
jumps to the first record.
`forms-last-record'
jumps to the last record. Also re-counts the number of records in
the data file.
`forms-next-field'
jumps to the next field in the forms. With a numeric argument:
jumps that many fields, or to the first field if there are not
that many fields left.
Jumping to fields is implemented using markers, which are placed
in front of the fields. If the contents of the forms are modified,
the markers are adjusted. However, if text around a marker has
been deleted from the screen and inserted again it is possible
that this marker no longer points at its field correctly. *Note
Markers: (emacs)Markers, for more information on markers.
`forms-view-mode'
switches to read-only mode. Forms mode commands may no longer be
prefixed with `C-c'.
`forms-edit-mode'
switches to edit mode. Forms mode commands must be prefixed with
`C-c'.
Switching to edit mode is only possible if write access to the data
file is allowed.
`forms-insert-record'
create a new record, which is inserted before the current record.
An empty form is presented, which can be filled in using familiar
editor commands. With a prefix argument: the new record is created
after the current one.
If a function `forms-new-record-filter' was defined in the control
file, this function is called to fill in default values for
fields. The function is passed a vector of empty strings, one for
each field. For convenience, an additional element is added so the
numbers of the elements are the same as the numbers used in the
forms description. The function must return the (updated) vector.
Instead of defining the function, `forms-new-record-filter' may be
set to a function.
Example:
(defun my-new-record-filter (fields)
(aset fields 5 (login-name))
(aset fields 1 (current-time-string))
;; and return it
fields)
(setq forms-new-record-filter 'my-new-record-filter)
`forms-delete-record'
deletes the current record. You are prompted for confirmation
before the record is deleted unless a prefix argument has been
provided.
`forms-search REGEXP'
searches for REGEXP in all records following this one. If found,
this record is shown.
The next time it is invoked, the previous regexp is the default,
so you can do repeated searches by simply pressing RET in response
to the prompt.
`revert-buffer'
reverts a possibly modified forms to its original state. It only
affect the record currently in the forms.
`forms-exit'
terminates forms processing. The data file is saved if it has been
modified.
`forms-exit-no-save'
aborts forms processing. If the data file has been modified Emacs
will ask questions.
`describe-mode'
gives additional help.
`save-buffer'
saves the changes in the data file, if modified.
If the variable `forms-forms-scrolls' is set to a value other than
`nil' (which it is, by default), the Emacs functions `scroll-up' and
`scroll-down' will perform a `forms-next-record' and
`forms-prev-record' when in forms mode. So you can use your favourite
page commands to page through the data file.
Likewise, if the variable `forms-forms-jump' is not `nil' (which it
is, by default), Emacs functions `beginning-of-buffer' and
`end-of-buffer' will perform `forms-first-record' and
`forms-last-record' when in forms mode.
After forms mode is entered, functions contained in
`forms-mode-hooks' are executed to perform user defined customization.
File: forms, Node: Key Bindings, Next: Miscellaneous, Prev: Forms Mode Commands, Up: Top
Key bindings
============
This section describes the key bindings as they are defined when
invoking forms mode.
All commands must be prefixed with `C-c' when editing a forms. If a
forms is read-only, `C-c' is not used. The only exception to this rule
is `forms-next-field', which is bound to `TAB' in all maps.
`C-c TAB'
`forms-next-field'
`C-c SPC'
`forms-next-record'
`C-c <'
`forms-first-record'
`C-c >'
`forms-first-record'
`C-c d'
`forms-delete-record'
`C-c e'
`forms-edit-mode'
`C-c i'
`forms-insert-record'
`C-c j'
`forms-jump-record'
`C-c n'
`forms-next-record'
`C-c p'
`forms-prev-record'
`C-c q'
`forms-exit'
`C-c s REGEXP'
`forms-search'
`C-c v'
`forms-view-mode'
`C-c x'
`forms-exit-no-save'
`C-c ?'
`describe-mode'
`C-c DEL'
`forms-prev-record'
File: forms, Node: Miscellaneous, Next: Error Messages, Prev: Key Bindings, Up: Top
Miscellaneous
=============
A global variable `forms-version' holds the version information of
the current implementation of forms mode.
It is very convenient to use symbolic names for the fields in a
record. The function `forms-enumerate' provides an elegant means to
define a series of variables to consecutive numbers. The function
returns the higest number used, so it can be used to set
`forms-number-of-fields' also:
(setq forms-number-of-fields
(forms-enumerate
'(field1 field2 field3 ... )))
`field1' will be set to 1, `field2' to 2 and so on.
Care has been taken to localize the current information of the forms
mode, so it is possible to visit multiple files in forms mode
simultaneously, even if they have different properties.
Since buffer-local functions are not available in this version of GNU
Emacs, the definitions of the filter functions
`forms-new-record-filter' and `forms-modified-record-filter' are copied
into internal, buffer local variables when forms-mode is initialized.
If a control file is visited using the standard `find-file'
commands, forms mode can be enabled with the command `M-x forms-mode'.
Forms mode will be automatically enabled if the file contains the
string `"-*- forms -*-"' somewhere in the first line. However, this
makes it hard to edit the control file itself so you'd better think
twice before using this.
The default format for the data file, using TAB to separate fields
and `C-k' to separate multi-line fields, matches the file format of
some popular Macintosh database programs, e.g. FileMaker. So
`forms-mode' could decrease the need to use Apple computers.
File: forms, Node: Error Messages, Next: Examples, Prev: Miscellaneous, Up: Top
Error Messages
==============
This section describes all error messages which can be generated by
forms mode.
`'forms-file' has not been set'
The variable `forms-file' was not set by the control file.
`'forms-number-of-fields' has not been set'
The variable `forms-number-of-fields' was not set by the control
file.
`'forms-number-of-fields' must be > 0'
The variable `forms-number-of-fields' did not contain a positive
number.
`'forms-field-sep' is not a string'
`'forms-multi-line' must be nil or a one-character string'
The variable `forms-multi-line' was set to something other than
`nil or' a single-character string.
`'forms-multi-line' is equal to 'forms-field-sep''
The variable `forms-multi-line' may not be equal to
`forms-field-sep' for this would make it impossible to distinguish
fields and the lines in the fields.
`'forms-format-list' has not been set'
`'forms-format-list' is not a list'
The variable `forms-format-list' was not set to a lisp `list' by
the control file.
`Forms error: field number XX out of range 1..NN'
A field number was supplied with a value of XX, which was not
greater than zero and smaller than or equal to the number of
fields in the forms, NN.
`Forms error: not a function FUN'
The first element of the lisp list specified in `forms-format-list'
did not have a function value.
`Invalid element in 'forms-format-list': XX'
A list element was supplied in `forms-format-list' which was not a
`string', `number' nor a `lisp list'.
`Parse error: not looking at "..."'
When re-parsing the contents of a forms, the text shown could not
be found.
`Parse error: cannot find "..."'
When re-parsing the contents of a forms, the text shown, which
separates two fields, could not be found.
`Parse error: cannot parse adjacent fields XX and YY'
Fields XX and YY were not separated by text, so could not be
parsed again.
`Record has XX fields instead of YY'
The number of fields in this record in the data file did not match
`forms-number-of-fields'. Missing fields will be set to empty.
`Multi-line fields in this record - update refused!'
The current record contains newline characters, hence can not be
written back to the data file, for it would corrupt it.
probably a field was set to a multi-line value, while the setting
of `forms-multi-line' prohibited this.
`Record number XX out of range 1..YY'
A jump was made to non-existing record XX. YY denotes the number
of records in the file.
`Stuck at record XX'
An internal error prevented a specific record from being retrieved.
File: forms, Node: Examples, Next: Credits, Prev: Error Messages, Up: Top
Examples
========
The following example exploits most of the features of forms-mode.
This example is included in the distribution as file `forms-d2.el'.
;; demo2 -- demo forms-mode -*- emacs-lisp -*-
;; SCCS Status : demo2 1.1.2
;; Author : Johan Vromans
;; Created On : 1989
;; Last Modified By: Johan Vromans
;; Last Modified On: Mon Jul 1 13:56:31 1991
;; Update Count : 2
;; Status : OK
;;
;; This sample forms exploit most of the features of forms mode.
;; Set the name of the data file.
(setq forms-file "forms-d2.dat")
;; Use 'forms-enumerate' to set field names and number thereof.
(setq forms-number-of-fields
(forms-enumerate
'(arch-newsgroup ; 1
arch-volume ; 2
arch-issue ; and ...
arch-article ; ... so
arch-shortname ; ... ... on
arch-parts
arch-from
arch-longname
arch-keywords
arch-date
arch-remarks)))
;; The following functions are used by this form for layout purposes.
;;
(defun arch-tocol (target &optional fill)
"Produces a string to skip to column TARGET. Prepends newline if needed.
The optional FILL should be a character, used to fill to the column."
(if (null fill)
(setq fill ? ))
(if (< target (current-column))
(concat "\n" (make-string target fill))
(make-string (- target (current-column)) fill)))
;;
(defun arch-rj (target field &optional fill)
"Produces a string to skip to column TARGET minus the width of field FIELD.
Prepends newline if needed. The optional FILL should be a character,
used to fill to the column."
(arch-tocol (- target (length (nth field forms-fields))) fill))
;; Record filters.
;; This example uses the (defun ...) method of defining.
;;
(defun forms-new-record-filter (the-record)
"Form a new record with some defaults."
(aset the-record arch-from (user-full-name))
(aset the-record arch-date (current-time-string))
the-record ; return it
)
;; The format list.
(setq forms-format-list
(list
"====== Public Domain Software Archive ======\n\n"
arch-shortname
" - " arch-longname
"\n\n"
"Article: " arch-newsgroup
"/" arch-article
" "
'(arch-tocol 40)
"Issue: " arch-issue
" "
'(arch-rj 73 10)
"Date: " arch-date
"\n\n"
"Submitted by: " arch-from
"\n"
'(arch-tocol 79 ?-)
"\n"
"Keywords: " arch-keywords
"\n\n"
"Parts: " arch-parts
"\n\n====== Remarks ======\n\n"
arch-remarks
))
;; That's all, folks!
File: forms, Node: Credits, Next: Concept Index, Prev: Examples, Up: Top
Credits
=======
Forms mode is developed by Johan Vromans `<jv@mh.nl>' at Multihouse
Research in the Netherlands.
Harald Hanche-Olsen `<hanche@imf.unit.no>' supplied the idea for the
new record filter, and provided better replacements for some internal
functions.
Bugfixes and other useful suggestions were supplied by
cwitty@portia.stanford.edu, Jonathan I. Kamens, Ignatios Souvatzis and
Harald Hanche-Olsen.
This documentation was slightly inspired by the documentation of
"rolo mode" by Paul Davis at Schlumberger Cambridge Research
`<davis%scrsu1%sdr.slb.com@relay.cs.net>'.
None of this would have been possible without GNU Emacs of the Free
Software Foundation. Thanks, Richard!
File: forms, Node: Concept Index, Next: Variable Index, Prev: Credits, Up: Top
Concept Index
*************
* Menu:
* forms-mode: Top.
* pseudo-newline: Data File Format.
File: forms, Node: Variable Index, Next: Function Index, Prev: Concept Index, Up: Top
Variable Index
**************
* Menu:
* forms-field-sep: Control File Format.
* forms-fields: Forms Format Description.
* forms-file: Control File Format.
* forms-format-list: Forms Format Description.
* forms-format-list: Control File Format.
* forms-forms-jump: Control File Format.
* forms-forms-jump: Forms Mode Commands.
* forms-forms-scroll: Forms Mode Commands.
* forms-forms-scroll: Control File Format.
* forms-mode-hooks: Forms Mode Commands.
* forms-multi-line: Control File Format.
* forms-number-of-fields: Control File Format.
* forms-read-only: Control File Format.
* forms-version: Miscellaneous.
File: forms, Node: Function Index, Prev: Variable Index, Up: Top
Function Index
**************
* Menu:
* beginning-of-buffer: Forms Mode Commands.
* describe-mode: Forms Mode Commands.
* end-of-buffer: Forms Mode Commands.
* eval-current-buffer: Control File Format.
* forms-delete-record: Forms Mode Commands.
* forms-edit-mode: Forms Mode Commands.
* forms-enumerate: Miscellaneous.
* forms-exit: Forms Mode Commands.
* forms-exit-no-save: Forms Mode Commands.
* forms-find-file: Forms Mode Commands.
* forms-find-file-other-window: Forms Mode Commands.
* forms-first-record: Forms Mode Commands.
* forms-insert-record: Forms Mode Commands.
* forms-jump-record: Forms Mode Commands.
* forms-last-record: Forms Mode Commands.
* forms-modified-record-filter: Modifying Forms Contents.
* forms-modified-record-filter: Control File Format.
* forms-new-record-filter: Control File Format.
* forms-next-field: Forms Mode Commands.
* forms-next-record: Forms Mode Commands.
* forms-prev-record: Forms Mode Commands.
* forms-search: Forms Mode Commands.
* forms-view-mode: Forms Mode Commands.
* revert-buffer: Forms Mode Commands.
* save-buffer: Forms Mode Commands.
* scroll-down: Forms Mode Commands.
* scroll-up: Forms Mode Commands.
Tag Table:
Node: Top
Node: What is in a Forms
Node: Data File Format
Node: Control File Format
Node: Forms Format Description
Node: Modifying Forms Contents
Node: Forms Mode Commands
10941
Node: Key Bindings
16738
Node: Miscellaneous
17694
Node: Error Messages
19457
Node: Examples
22244
Node: Credits
25306
Node: Concept Index
26092
Node: Variable Index
26320
Node: Function Index
27312
End Tag Table