mule-base / texi / quail.texi

\input texinfo	@c -*-texinfo-*-
@setfilename ../info/quail
@settitle QUAIL -- Imputting methods of multilingual text

@titlepage
@sp 6
@center @titlefont{QUAIL -- Imputting methods of multilingual text}
@sp 4
@center Version 2.0
@sp 5
@center Ken'ichi HANDA
@center handa@@etl.go.jp
@page

@end titlepage

@node Top, , , (mule)
@section QUAIL -- Imputting methods of multilingual text

Quail is a simple key-translation system which allows users
to input any multilingual text from normal ASCII keyboard.

We provide several quail-packages, each package corresponds
to one inputting methods.  For instance, the file
lisp/quail/py.el provides a package for inputting Chinese by
PinYin.  lisp/quail/hangul.el provides a package for
inputting Korean.

@menu
* Usage of Quail::
* Structure of Quail::  For quail package writers.
@end menu

@node Usage of Quail, Structure of Quail, , Top
@section Usage of Quail

You can load several packages at once but only the
translation rules defined in the current package are
effective.  Quail-mode is toggled by C-].  When you enter in
quail-mode, the current package is shown at the left of modeline as:
@quotation
@code{[xxxxx]}
@end quotation
where xxxxx is the multilingual text for the current
package.  In quail-mode, M-s changes the current package
(normal completion is performed by hitting <SPC> or <TAB>).

In quail-mode, all graphic keys you type is translated
according to the rules of the current package.  Brief
description about the rules and key-bindings are shown by
M-z.

While there are more than one candidates for what you type,
the first candidate is shown in buffer with underscore.  By
M-n and M-p you can select any other candidate.  M-i shows
list of candidates (showing each candidate with index number
[two digits]).  You can select one also by typing these
digits.

Once you select a desired candidate, please just type a key
for another character.  The underscore moves to the next key
automatically.  But, in some packages (e.g. hangul),
there are rules something like:
@example
	ab  -> A
	aba -> B
	b   -> C
@end example

In this case, if you type "abab", quail will enter "AA".  If
what you want is "BC", you must explicitly tell the division
point of the character by hitting <SPC>.  In this example,
you should have typed "aba<SPC>b".

Here's the summary of command keys:
@example
------------------------------------------------------------
C-]:	Exit from quail-mode.
DEL:	Delete characters backward in quail-mode.
M-i:	Show list of candidates.
M-n:	Select next candidate.
M-p:	Select previous candidate.
M-s:	Select quail-package.
M-z:	Show brief description of the current quail-pacakge.
------------------------------------------------------------
@end example

@node Structure of Quail, , Usage of Quail, Top
@section Structure of Quail

#### NOT COMPLETED, NOT UPDATED ####

This section is intended to help emacslisper who try to
debug or enhance 'quail' system.  The original code quail.el
is located under the directory mule/lisp/quail.el.

Quail serves as a front end processor for inputing
multilingual text from normal ASCII keyboard.  By defining a
translation table which maps ASCII string to multilingual
string, you can input any text from ASCII keyboard.

For the momemnt, translation table for Chinese inputing
distributed with X.V11R5/contrib/cxterm are supported in
mule/lisp/quail/XXXX.el files.  You can use the system also
for inputing various Korean/European characters.

Quail system registers translation table in keymap of Emacs,
thus table lookup is done just by calling function
@code{lookup-key}, and new registration is done just by calling
function 'define-key'.  Keymap is represented as a
structured association list.  For instance, a translation
table of the form ("a" -> "A" or "a", "ab" -> "AB", "c" ->
"C") is represented as follows:

@example
  (keymap . ((?a . (keymap . ((?\377 . '(0 "A" "a")
			      (?b . (keymap . ((?\377 . '(0 "AB")))))))))
	     (?c . (keymap . ((?\377 . '(0 "C")))))))
@end example

As you see, the final string of translation is registered
under the tag of ?\377.  Hence, the following program
creates the map above.

@example
	(setq m (make-sparce-keymap))
	(define-key m "a\377" '(0 "A" "a") t)
	(define-key m "ab\377" '(0 "AB") t)
	(define-key m "c\377" '(0 "C") t)
@end example

Each '0' means that the first candidate in the list is
selected at first.  In this case, according to your typing,
buffer contents changes as follows:

@example
	Type:	a	M-n	b	c	a	b
	Buffer:	A	a	AB	ABc	ABca	ABcab
	Uline:	-	-	--	  -	   -
@end example

where Uline shows which characters are displayed with
underline.  While underline is shown, we say that quail is
in 'translation state'.  We assumed that M-n is bound to
@code{quail-next-candidate}.

The last argument of @code{define-key} 't' means that meta
characters in the key-string are processed as is (not as ESC
+ char), which is a Mule specific facility.  Since keymaps
can be nested, you can share one keymap (say m) with two
other keymaps (say m1 and m2) by:

@example
	(define-key m1 "x" m)
	(define-key m2 "y" m)
@end example

This means the translation ("xa" -> "A" or "a", "xab" ->
"AB", "xac" -> "C") in map m1 and ("ya" -> "A" or "a", "yab"
-> "AB", "yac" -> "C") in m2.

We call a keymap which satisfies the description above as a
'quail-map' here after.  Quail handles a quail-map with
additional information as a 'quail-package'.  Each
quail-package holds the following information as a list:

@enumerate
@item
name (string [ASCII only]): Name of the package.

@item
prompt (string [any characters]): 
A string shown in mode-line as a name of quail mode.

@item
quail-map: A quail map described above.

@item
showkey (alist):
An alist of character typed and corresponding string to be shown in echo
area.  For instance, quail-package namede "ccdospy" has the following
showkey:

@example
 '((?a . "zh") (?f . "en") (?g ."eng") (?h . "ang") (?i . "ch") (?j . "an")
   (?k . "ao") (?l . "ai") (?s . "ong") (?u . "sh") (?y . "ing") (?v . "yu"))
@end example

This says that if you type 'a', "zh" is shown in echo area.
If 'f' is followed by 'a', "zhen" is shown.

@item
document (string): A document shown by quail-help command.

@item
mode-map (keymap): 
A keymap to control quail mode.  This defaults to
@code{quail-mode-default-map}.  Prefix character is restricted to ESC only,
which means you can not define such key sequence as "\C-xi" in this map.
In addition, defining '!' through '~' are no use because those keys are
overridden by @code{quail-self-insert-command}.

@item
nolearn (flag):
A flag to control learning facility of quail.  If this flag is non-nil,
quail does not remember the last selection of candidate string for the
later selection.

@item
deterministic (flag):
A flag to specify that only one target string is defined in the
quail-map for each key sequence (i.e. no alternative candidates).  If
this flag is non-nil, quail automatically exit from the translation
state when a target string for a key sequence is found.
@end enumerate

All packages defined are in @code{quail-package-alist} (see
document of quail-define-package).

Users are recommended not to modify quail-map directly but
to use quail-defrule function (see document of quail-defrule).

You may find the example of defining quail package and
defining translation rule of the package in
lisp/quail/latin.el

Quail system works as one of a minor mode so that it works
under any major modes.  But, the way of handling non-quail
commands are very different from that of the other minor
modes.  All keys typed are eaten by the system because, in
quail mode, keys except for invoking quail specific commands
are bound to 'quail-non-quail-command.  The function, at
first, resets quail translation status (we'll explain it
below), then, checks the original binding of the key in
local map or global map and invokes the command bound to the
key.

Quail keeps the current state of transformation with the
following variables:

@itemize
@item @code{quail-overlay}

Keep points of start and end of a string inserted by
the system.  The string is one of below.

@item @code{quail-current-key}

A key string typed so far for the current translation.
When there's no translation for the key, this string
is inserted in a buffer temporally.

@item @code{quail-current-str}

A string translated from @code{quail-current-key}.  In addition,
attribute region is set automatically around the sting inserted in a
buffer.
@end itemize

@contents
@bye
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