mdbGeneral(5) The m17n Library mdbGeneral(5)
NAME
mdbGeneral - General Format
DESCRIPTION
The mdatabase_load() function returns the data specified by tags in the
form of plist if the first tag is not Mchartable nor Mcharset. The keys
of the returned plist are limited to Minteger, Msymbol, Mtext, and
Mplist. The type of the value is unambiguously determined by the
corresponding key. If the key is Minteger, the value is an integer. If
the key is Msymbol, the value is a symbol. And so on.
A number of expressions are possible to represent a plist. For instance,
we can use the form (K1:V1, K2:V2, ..., Kn:Vn) to represent a plist
whose first property key and value are K1 and V1, second key and value
are K2 and V2, and so on. However, we can use a simpler expression here
because the types of plists used in the m17n database are fairly
restricted.
Hereafter, we use an expression, which is similar to S-expression, to
represent a plist. (Actually, the default database loader of the m17n
library is designed to read data files written in this expression.)
The expression consists of one or more elements. Each element represents
a property, i.e. a single element of a plist.
Elements are separated by one or more whitespaces, i.e. a space (code
32), a tab (code 9), or a newline (code 10). Comments begin with a
semicolon (;) and extend to the end of the line.
The key and the value of each property are determined based on the type
of the element as explained below.
• INTEGER
An element that matches the regular expression -?[0-9]+ or
0[xX][0-9A-Fa-f]+ represents a property whose key is Minteger. An
element matching the former expression is interpreted as an integer in
decimal notation, and one matching the latter is interpreted as an
integer in hexadecimal notation. The value of the property is the result
of interpretation.
For instance, the element 0xA0 represents a property whose value is 160
in decimal.
• SYMBOL
An element that matches the regular expression [^-(0-9]([^\()]|\.)+
represents a property whose key is Msymbol. In the element, \t, \n, \r,
and \e are replaced with tab (code 9), newline (code 10), carriage
return (code 13), and escape (code 27) respectively. Other characters
following a backslash is interpreted as it is. The value of the property
is the symbol having the resulting string as its name.
For instance, the element abc\ def represents a property whose value is
the symbol having the name 'abc def'.
• MTEXT
An element that matches the regular expression '([^']|\')*' represents a
property whose key is Mtext. The backslash escape explained above also
applies here. r, each part in the element matching the regular
expression \[xX][0-9A-Fa-f][0-9A-Fa-f] is replaced with its hexadecimal
interpretation.
After having resolved the backslash escapes, the byte sequence between
the double quotes is interpreted as a UTF-8 sequence and decoded into an
M-text. This M-text is the value of the property.
• PLIST
Zero or more elements surrounded by a pair of parentheses represent a
property whose key is Mplist. Whitespaces before and after a parenthesis
can be omitted. The value of the property is a plist, which is the
result of recursive interpretation of the elements between the
parentheses.
SYNTAX NOTATION
In an explanation of a plist format of data, a BNF-like notation is
used. In the notation, non-terminals are represented by a string of
uppercase letters (including '-' in the middle), terminals are
represented by a string surrounded by '''. Special non-terminals
INTEGER, SYMBOL, MTEXT and PLIST represents property integer, symbol,
M-text, or plist respectively.
EXAMPLE
Here is an example of database data that is read into a plist of this
simple format:
DATA-FORMAT ::=
[ INTEGER | SYMBOL | MTEXT | FUNC ] *
FUNC ::=
'(' FUNC-NAME FUNC-ARG * ')'
FUNC-NAME ::=
SYMBOL
FUNC-ARG ::=
INTEGER | SYMBOL | MTEXT | '(' FUNC-ARG ')'
For instance, a data file that contains this text matches the above
syntax:
abc 123 (pqr 0xff) "m
and is read into this plist:
1st element: key: Msymbol, value: abc
2nd element: key: Minteger, value: 123
3rd element: key: Mplist, value: a plist of these elements:
1st element: key Msymbol, value: pgr
2nd element: key Minteger, value: 255
4th element: key: Mtext, value: m"text
5th element: key: Mplist, value: a plist of these elements:
1st element: key: Msymbol, value: __
2nd element: key: Mplist, value: a plist of these elements:
1st element: key: Mtext, value: string
2nd element: key: Msymbol, value: xyz
3rd element: key: Minteger, value: -456
COPYRIGHT
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
<http://www.gnu.org/licenses/fdl.html>.
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