Provided by: m17n-docs_1.6.2-1_all
mdbIM - Input Method
The m17n library provides a driver for input methods that are
dynamically loadable from the m17n database (see m17nInputMethod ).
This section describes the data format that defines those input
SYNTAX and SEMANTICS
The following data format defines an input method. The driver loads a
definition from a file, a stream, etc. The definition is converted into
the form of plist in the driver.
IM-DECLARATION ? IM-DESCRIPTION ? TITLE ?
VARIABLE-LIST ? COMMAND-LIST ? MODULE-LIST ?
MACRO-LIST ? MAP-LIST ? STATE-LIST ?
IM-DECLARATION ::= '(' 'input-method' LANGUAGE NAME EXTRA-ID ? VERSION ? ')'
LANGUAGE ::= SYMBOL
NAME ::= SYMBOL
EXTRA-ID ::= SYMBOL
VERSION ::= '(' 'version' VERSION-NUMBER ')'
IM-DESCRIPTION ::= '(' 'description' DESCRIPTION ')'
DESCRIPTION ::= MTEXT-OR-GETTEXT | 'nil'
MTEXT-OR-GETTEXT ::= [ MTEXT | '(' '_' MTEXT ')']
TITLE ::= '(' 'title' TITLE-TEXT ')'
TITLE-TEXT ::= MTEXT
VARIABLE-LIST ::= '(' 'variable' VARIABLE-DECLARATION * ')'
VARIABLE-DECLARATION ::= '(' VAR-NAME [ DESCRIPTION VALUE VALUE-CANDIDATE * ]')'
VAR-NAME ::= SYMBOL
VALUE ::= MTEXT | SYMBOL | INTEGER
VALUE-CANDIDATE ::= VALUE | '(' RANGE-FROM RANGE-TO ')'
RANGE-FROM ::= INTEGER
RANGE-TO ::= INTEGER
COMMAND-LIST ::= '(' 'command' COMMAND-DECLARATION * ')'
COMMAND-DECLARATION ::= '(' CMD-NAME [ DESCRIPTION KEYSEQ * ] ')'
CMD-NAME ::= SYMBOL
IM-DECLARATION specifies the language and name of this input method.
When LANGUAGE is t, the use of the input method is not limited to one
When NAME is nil, the input method is not standalone, but is expected
to be used in other input methods. In such cases, EXTRA-ID is required
to identify the input method.
VERSION specifies the required minimum version number of the m17n
library. The format is 'XX.YY.ZZ' where XX is a major version number,
YY is a minor version number, and ZZ is a patch level.
DESCRIPTION, if not nil, specifies the description text of an input
method, a variable or a command. If MTEXT-OR-GETTEXT takes the second
form, the text is translated according to the current locale by
'gettext' (if the translation is provided).
TITLE-TEXT is a text displayed on the screen when this input method is
There is one special input method file 'global.mim' that declares
common variables and commands. The input method driver always loads
this file and other input methods can inherit the variables and the
VARIABLE-DECLARATION declares a variable used in this input method. If
a variable must be initialized to the default value, or is to be
customized by a user, it must be declared here. The declaration can be
used in two ways. One is to introduce a new variable. In that case,
VALUE must not be omitted. Another is to inherit the variable from what
declared in 'global.mim', and to give the different default value
and/or to make the variable customizable specially for the current
input method. In the latter case, VALUE can be omitted.
COMMAND-DECLARATION declares a command used in this input method. If a
command must be bound to the default key sequence, or is to be
customized by a user, it must be declared here. Like
VARIABLE-DECLARATION, the declaration can be used in two ways. One is
to introduce a new command. In that case, KEYSEQ must not be omitted.
Another is to inherit the command from what declared in 'global.mim',
and to give the different key binding and/or to make the command
customizable specially for the current input method. In the latter
case, KEYSEQ can be omitted.
MODULE-LIST ::= '(' 'module' MODULE * ')'
MODULE ::= '(' MODULE-NAME FUNCTION * ')'
MODULE-NAME ::= SYMBOL
FUNCTION ::= SYMBOL
Each MODULE declares the name of an external module (i.e. dynamic
library) and function names exported by the module. If a FUNCTION has
name 'init', it is called with only the default arguments (see the
section about CALL) when an input context is created for the input
method. If a FUNCTION has name 'fini', it is called with only the
default arguments when an input context is destroyed.
MACRO-LIST ::= MACRO-INCLUSION ? '(' 'macro' MACRO * ')' MACRO-INCLUSION ?
MACRO ::= '(' MACRO-NAME MACRO-ACTION * ')'
MACRO-NAME ::= SYMBOL
MACRO-ACTION ::= ACTION
TAGS ::= `(` LANGUAGE NAME EXTRA-ID ? `)`
MACRO-INCLUSION ::= '(' 'include' TAGS 'macro' MACRO-NAME ? ')'
MACRO-INCLUSION includes macros from another input method specified by
TAGS. When MACRO-NAME is not given, all macros from the input method
MAP-LIST ::= MAP-INCLUSION ? '(' 'map' MAP * ')'
MAP ::= '(' MAP-NAME RULE * ')'
MAP-NAME ::= SYMBOL
RULE ::= '(' KEYSEQ MAP-ACTION * ')'
KEYSEQ ::= MTEXT | '(' [ SYMBOL | INTEGER ] * ')'
MAP-INCLUSION ::= '(' 'include' TAGS 'map' MAP-NAME ? ')'
When an input method is never standalone and always included in another
method, MAP-LIST can be omitted.
SYMBOL in the definitions of MAP-NAME must not be t nor nil.
MTEXT in the definition of KEYSEQ consists of characters that can be
generated by a keyboard. Therefore MTEXT usually contains only ASCII
characters. However, if the input method is intended to be used, for
instance, with a West European keyboard, MTEXT may contain Latin-1
SYMBOL in the definition of KEYSEQ must be the return value of the
minput_event_to_key() function. Under the X window system, you can
quickly check the value using the xev command. For example, the return
key, the backspace key, and the 0 key on the keypad are represented as
(Return) , (BackSpace) , and (KP_0) respectively. If the shift,
control, meta, alt, super, and hyper modifiers are used, they are
represented by the S- , C- , M- , A- , s- , and H- prefixes
respectively in this order. Thus, 'return with shift with meta with
hyper' is (S-M-H-Return) . Note that 'a with shift' .. 'z with shift'
are represented simply as A .. Z . Thus 'a with shift with meta with
hyper' is (M-H-A) .
INTEGER in the definition of KEYSEQ must be a valid character code.
MAP-INCLUSION includes maps from another input method specified by
TAGS. When MAP-NAME is not given, all maps from the input method are
MAP-ACTION ::= ACTION
ACTION ::= INSERT | DELETE | SELECT | MOVE | MARK
| SHOW | HIDE | PUSHBACK | POP | UNDO
| COMMIT | UNHANDLE | SHIFT | CALL
| SET | IF | COND | '(' MACRO-NAME ')'
'@0' | '@1' | '@2' | '@3' | '@4'
| '@5' | '@6' | '@7' | '@8' | '@9'
| '@<' | '@=' | '@>' | '@-' | '@+' | '@[' | '@]'
| '@-0' | '@-N' | '@+N'
STATE-LIST ::= STATE-INCUSION ? '(' 'state' STATE * ')' STATE-INCUSION ?
STATE ::= '(' STATE-NAME [ STATE-TITLE-TEXT ] BRANCH * ')'
STATE-NAME ::= SYMBOL
STATE-TITLE-TEXT ::= MTEXT
BRANCH ::= '(' MAP-NAME BRANCH-ACTION * ')'
| '(' 'nil' BRANCH-ACTION * ')'
| '(' 't' BRANCH-ACTION * ')'
STATE-INCLUSION ::= '(' 'include' TAGS 'state' STATE-NAME ? ')'
When an input system is never standalone and always included in another
system, STATE-LIST can be omitted.
STATE-INCLUSION includes states from another input method specified by
TAGS. When STATE-NAME is not given, all states from the input method
The optional STATE-TITLE-TEXT specifies a title text displayed on the
screen when the input method is in this state. If STATE-TITLE-TEXT is
omitted, TITLE-TEXT is used.
In the first form of BRANCH, MAP-NAME must be an item that appears in
MAP. In this case, if a key sequence matching one of KEYSEQs of
MAP-NAME is typed, BRANCH-ACTIONs are executed.
In the second form of BRANCH, BRANCH-ACTIONs are executed if a key
sequence that doesn't match any of Branch's of the current state is
If there is no BRANCH beginning with nil and the typed key sequence
does not match any of the current BRANCHs, the input method transits to
the initial state.
In the third form of BRANCH, BRANCH-ACTIONs are executed when shifted
to the current state. If the current state is the initial state,
BRANCH-ACTIONs are executed also when an input context of the input
method is created.
BRANCH-ACTION ::= ACTION
An input method has the following two lists of symbols.
o marker list
A marker is a symbol indicating a character position in the preediting
text. The MARK action assigns a position to a marker. The position of a
marker is referred by the MOVE and the DELETE actions.
o variable list
A variable is a symbol associated with an integer, a symbol, or an
M-text value. The integer value of a variable can be set and referred
by the SET action. It can be referred by the SET, the INSERT, the
SELECT, the UNDO, the IF, the COND actions. The M-text value of a
variable can be referred by the INSERT action. The symbol value of a
variable can not be referred directly, is used the library implicitly
(e.g. candidates-charset). All variables are implicitly initialized to
the integer value zero.
Each PREDEFINED-SYMBOL has a special meaning when used as a marker.
o @0, @1, @2, @3, @4, @5, @6, @7, @8, @9
The 0th, 1st, 2nd, ... 9th position respectively.
o @<, @=, @>
The first, the current, and the last position.
o @-, @+
The previous and the next position.
o @[, @]
The previous and the next position where a candidate list changes.
Some of the PREDEFINED-SYMBOL has a special meaning when used as a
candidate index in the SELECT action.
o @<, @=, @>
The first, the current, and the last candidate of the current candidate
The previous candidate. If the current candidate is the first one in
the current candidate group, then it means the last candidate in the
previous candidate group.
The next candidate. If the current candidate is the last one in the
current candidate group, then it means the first candidate in the next
o @[, @]
The candidate in the previous and the next candidate group having the
same candidate index as the current one.
And, this also has a special meaning.
Number of handled keys at that moment.
These are for supporting surround text handling.
-1 if surrounding text is supported, -2 if not.
Here, N is a positive integer. The value is the Nth previous character
in the preedit buffer. If there are only M (M<N) previous characters in
it, the value is the (N-M)th previous character from the inputting
spot. When this is used as the argument of delete action, it specifies
the number of characters to be deleted.
Here, N is a positive integer. The value is the Nth following character
in the preedit buffer. If there are only M (M<N) following characters
in it, the value is the (N-M)th following character from the inputting
spot. When this is used as the argument of delete action, it specifies
the number of characters to be deleted.
The arguments and the behavior of each action are listed below.
INSERT ::= '(' 'insert' MTEXT ')'
| '(' 'insert' SYMBOL ')'
| '(' 'insert' '(' CANDIDATES * ')' ')'
| '(' CANDIDATES * ')'
CANDIDATES ::= MTEXT | '(' MTEXT * ')'
The first and second forms insert MTEXT before the current position.
The third form inserts the character INTEGER before the current
The fourth and fith form treats SYMBOL as a variable, and inserts its
value (if it is a valid character code) before the current position.
In the sixth and seventh forms, each CANDIDATES represents a candidate
group, and each element of CANDIDATES represents a candidate, i.e. if
CANDIDATES is an M-text, the candidates are the characters in the
M-text; if CANDIDATES is a list of M-texts, the candidates are the
M-texts in the list.
These forms insert the first candidate before the current position. The
inserted string is associated with the list of candidates and the
information indicating the currently selected candidate.
The marker positions affected by the insertion are automatically
DELETE ::= '(' 'delete' SYMBOL ')'
| '(' 'delete' INTEGER ')'
The first form treats SYMBOL as a marker, and deletes characters
between the current position and the marker position.
The second form treats INTEGER as a character position, and deletes
characters between the current position and the character position.
The marker positions affected by the deletion are automatically
SELECT ::= '(' 'select' PREDEFINED-SYMBOL ')'
| '(' 'select' INTEGER ')'
| '(' 'select' SYMBOL ')'
This action first checks if the character just before the current
position belongs to a string that is associated with a candidate list.
If it is, the action replaces that string with a candidate specified by
The first form treats PREDEFINED-SYMBOL as a candidate index (as
described above) that specifies a new candidate in the candidate list.
The second form treats INTEGER as a candidate index that specifies a
new candidate in the candidate list.
In the third form, SYMBOL must have a integer value, and it is treated
as a candidate index.
SHOW ::= '(show)' .fi
This actions instructs the input method driver to display a candidate list associated with the string before the current position.
HIDE ::= '(hide)'
This action instructs the input method driver to hide the currently
displayed candidate list.
MOVE ::= '(' 'move' SYMBOL ')'
| '(' 'move' INTEGER ')'
The first form treats SYMBOL as a marker, and makes the marker position
be the new current position.
The second form treats INTEGER as a character position, and makes that
position be the new current position.
MARK ::= '(' 'mark' SYMBOL ')'
This action treats SYMBOL as a marker, and sets its position to the
current position. SYMBOL must not be a PREDEFINED-SYMBOL.
PUSHBACK :: = '(' 'pushback' INTEGER ')'
| '(' 'pushback' KEYSEQ ')'
The first form pushes back the latest INTEGER number of key events to
the event queue if INTEGER is positive, and pushes back all key events
if INTEGER is zero.
The second form pushes back keys in KEYSEQ to the event queue.
POP ::= '(' 'pop' ')'
This action pops the first key event that is not yet handled from the
UNDO :: = '(' 'undo' [ INTEGER | SYMBOL ] ')'
If there's no argument, this action cancels the last two key events
(i.e. the one that invoked this command, and the previous one).
If there's an integer argument NUM, it must be positive or negative
(not zero). If positive, from the NUMth to the last events are
canceled. If negative, the last (- NUM) events are canceled.
If there's a symbol argument, it must be resolved to an integer number
and the number is treated as the actual argument as above.
COMMIT :: = '(commit)'
This action commits the current preedit.
UNHANDLE :: = '(unhandle)'
This action commits the current preedit and returns the last key as
SHIFT :: = '(' 'shift' STATE-NAME ')'
If STATE-NAME is t, this action shifts the current state to the
previous one, otherwise it shifts to STATE-NAME. In the latter case,
STATE-NAME must appear in STATE-LIST.
CALL ::= '(' 'call' MODULE-NAME FUNCTION ARG * ')'
ARG ::= INTEGER | SYMBOL | MTEXT | PLIST
This action calls the function FUNCTION of external module MODULE-NAME.
MODULE-NAME and FUNCTION must appear in MODULE-LIST.
The function is called with an argument of the type (MPlist *). The key
of the first element is Mt and its value is a pointer to an object of
the type MInputContext. The key of the second element is Msymbol and
its value is the current state name. ARGs are used as the value of the
third and later elements. Their keys are determined automatically; if
an ARG is an integer, the corresponding key is Minteger; if an ARG is a
symbol, the corresponding key is Msymbol, etc.
The function must return NULL or a value of the type (MPlist *) that
represents a list of actions to take.
SET ::= '(' CMD SYMBOL1 EXPRESSION ')'
CMD ::= 'set' | 'add' | 'sub' | 'mul' | 'div'
EXPRESSION ::= INTEGER | SYMBOL2 | '(' OPERATOR EXPRESSION * ')'
OPERATOR ::= '+' | '-' | '*' | '/' | '|' | '&' | '!'
| '=' | '<' | '>' | '<=' | '>='
This action treats SYMBOL1 and SYMBOL2 as variables and sets the value
of SYMBOL1 as below.
If CMD is 'set', it sets the value of SYMBOL1 to the value of
If CMD is 'add', it increments the value of SYMBOL1 by the value of
If CMD is 'sub', it decrements the value of SYMBOL1 by the value of
If CMD is 'mul', it multiplies the value of SYMBOL1 by the value of
If CMD is 'div', it divides the value of SYMBOL1 by the value of
IF ::= '(' CONDITION ACTION-LIST1 ACTION-LIST2 ? ')'
CONDITION ::= [ '=' | '<' | '>' | '<=' | '>=' ] EXPRESSION1 EXPRESSION2
ACTION-LIST1 ::= '(' ACTION * ')'
ACTION-LIST2 ::= '(' ACTION * ')'
This action performs actions in ACTION-LIST1 if CONDITION is true, and
performs ACTION-LIST2 (if any) otherwise.
COND ::= '(' 'cond' [ '(' EXPRESSION ACTION * ') ] * ')'
This action performs the first action ACTION whose corresponding
EXPRESSION has nonzero value.
This is a very simple example for inputting Latin characters with
diacritical marks (acute and cedilla). For instance, when you type:
you will get this:
The definition of the input method is very simple as below, and it is
quite straight forward to extend it to cover all Latin characters.
This example is for inputting Unicode characters by typing C-u
(Control-u) followed by four hexadecimal digits. For instance, when you
type ('^u' means Control-u):
you will get this (Unicode arrow symbols):
The definition utilizes SET and IF commands as below:
("0" ?0) ("1" ?1) ... ("9" ?9) ("a" ?A) ("b" ?B) ... ("f" ?F)))
(starter (set code 0) (set count 0) (shift unicode)))
(hex (set this @-)
(< this ?A
((sub this 48))
((sub this 55)))
(mul code 16) (add code this)
(add count 1)
(= count 4
((delete @<) (insert code) (shift init))))))
This example is for inputting Chinese characters by typing PinYin key
Input Methods provided by the m17n database, mdbGeneral(5)
Copyright (C) 2001 Information-technology Promotion Agency (IPA)
Copyright (C) 2001-2011 National Institute of Advanced Industrial
Science and Technology (AIST)
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License