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 methods.
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 language.
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
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
TITLE-TEXT is a text displayed on the screen when this input method is active.
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 commands.
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
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
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 are included.
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 characters.
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 included.
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 are included.
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 typed.
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
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.
- 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.
- 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.
- @0, @1, @2, @3, @4, @5, @6, @7, @8, @9
The 0th, 1st, 2nd, ... 9th position respectively.
- @<, @=, @>
The first, the current, and the last position.
- @-, @+
The previous and the next position.
- @[, @]
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.
- @<, @=, @>
The first, the current, and the last candidate of the current candidate group.
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
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 candidate
- @[, @]
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 position.
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 relocated.
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 relocated.
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 argument.
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
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
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
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 event
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 unhandled.
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
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 EXPRESSION.
If CMD is 'add', it increments the value of SYMBOL1 by the value of EXPRESSION.
If CMD is 'sub', it decrements the value of SYMBOL1 by the value of EXPRESSION.
If CMD is 'mul', it multiplies the value of SYMBOL1 by the value of EXPRESSION.
If CMD is 'div', it divides the value of SYMBOL1 by the value of EXPRESSION.
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
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
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 sequence.
Input Methods provided by the m17n database
Copyright (C) 2001 Information-technology Promotion Agency (IPA)
Copyright (C) 2001-2011 National Institute of Advanced Industrial Science and
Permission is granted to copy, distribute and/or modify this document under the
terms of the GNU Free Documentation License