X-Git-Url: http://git.chise.org/gitweb/?p=m17n%2Fm17n-docs.git;a=blobdiff_plain;f=data-usr%2Fdbformat.txt;h=0ad20fbad01bdcdc943aef23ca0bd1401367ec76;hp=3a8ecc1a92eeaa20cd267c763e36cc94ec41cd9c;hb=d5b639418e6f1532218a9ec58738290bd8f87322;hpb=021ab1a22c30d1edf07b79e6c99d2adef45e7476

diff --git a/data-usr/dbformat.txt b/data-usr/dbformat.txt
index 3a8ecc1..0ad20fb 100644
--- a/data-usr/dbformat.txt
+++ b/data-usr/dbformat.txt
@@ -1,61 +1,74 @@
-/***@page m17nDatabaseFormat DatabaseFormat
+/***@page m17nDatabaseFormat Data Format of the m17n database
 
-This section describes the formats of predefined @e plist @e type data
-in the m17n database.
+This section describes formats of data in the m17n database.
 
 @section dbformat General format
 
-The m17n library expects that the function mdatabase_load () returns a
-plist of a specific format on loading data identified by a specific
-set of tags.  As the plist format used for the database data is
-strongly limited, we can use the equivalent text of simple syntax
-(S-expression) to represent the plist as below.
-
-The text consists of one or more @e elements .  Each element
-represents a property, i.e. a single element of a plist, and the
-sequence of the elements constitute a plist.
-
-Elements are separated by one or more @e whitespaces, i.e. a space
+The mdatabase_load () function returns the data specified by tags in
+the form of plist if the first tag is not @c Mchartable nor @c
+Mcharset.  The keys of the returned plist are limited to
+<tt>Minteger</tt>, <tt>Msymbol</tt>, <tt>Mtext</tt>, and
+<tt>Mplist</tt>.  The type of the value is unambiguously determined by
+the corresponding key.  If the key is <tt>Minteger</tt>, the value is
+an integer.  If the key is <tt>Msymbol</tt>, 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 <tt>(K1:V1, K2:V2, ..., Kn:Vn)</tt> 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 <i>elements</i>.  Each element
+represents a property, i.e. a single element of a plist.
+
+Elements are separated by one or more <i>whitespaces</i>, i.e. a space
 (code 32), a tab (code 9), or a newline (code 10).  Comments begin
 with a semicolon (<tt>;</tt>) and extend to the end of the line.
 
 The key and the value of each property are determined based on the
-form of element as below:
+type of the element as explained below.
 
 <ul>
 
 <li> INTEGER
 
-An element that matches the regular expression @c -?[0-9]+ or @c
-0[xX][0-9A-Fa-f]+ represents a property whose key is @c Minteger .  An
-element matching the former expression is interpreted as an integer in
-decimal notation, and one matching the latter expression is
-interpreted as an integer in hexadecimal notation.  The resulting
-integer is the value of the property.
+An element that matches the regular expression <tt>-?[0-9]+</tt> or
+<tt>0[xX][0-9A-Fa-f]+</tt> represents a property whose key is
+<tt>Minteger</tt>.  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
-the integer 160.
+For instance, the element <tt>0xA0</tt> represents a property whose value is
+160 in decimal.
 
 <li> SYMBOL
 
-An element that matchs the regular expression @c
-[^-0-9(]([^\\()]|\\.)+ represents a property whose key is @c Msymbol .
-In the sequence, @c \\t , @c \\n , @c \\r , and @c \\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 symbol having the name of the resulting
-sequence is the value of the property.
+An element that matches the regular expression
+<tt>[^-0-9(]([^\\()]|\\.)+</tt> represents a property whose key is
+<tt> Msymbol</tt>.  In the element, <tt>\\t</tt>, <tt>\\n</tt>,
+<tt>\\r</tt>, and <tt>\\e</tt> 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 <tt>abc\ def</tt> represents a property
-whose value is the symbol of name "abc def".
+whose value is the symbol having the name "abc def".
 
 <li> M-TEXT
 
-An element that matches the regular expression @c "([^"]|\\")*"
-represents a property whose key is @c Mtext .  The backslash escape
+An element that matches the regular expression <tt>"([^"]|\\")*"</tt>
+represents a property whose key is <tt>Mtext</tt>.  The backslash escape
 explained above also applies here.  Moreover, each part in the
-sequence matching the regular expression @c
-\\[xX][0-9A-Fa-f][0-9A-Fa-f] is replaced with its hexadecimal
+element matching the regular expression <tt>
+\\[xX][0-9A-Fa-f][0-9A-Fa-f]</tt> is replaced with its hexadecimal
 interpretation.
 
 After having resolved the backslash escapes, the byte sequence between
@@ -64,24 +77,25 @@ an M-text.  This M-text is the value of the property.
 
 <li> PLIST
 
-An element that is preceded by a left parenthesis, followed zero or
-more elements, and terminated by a right parenthesis represents a
-property whose key is @c Mplist .  Parentheses also serve as a
-separator, which means 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.
+Zero or more elements surrounded by a pair of parentheses represent a
+property whose key is <tt>Mplist</tt>.  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.
 
 </ul>
 
 EXAMPLE
 
-Suppose (K1:V1, K2:V2, ... ,Kn:Vn) represents a plist whose first
-property key and value are K1 and V1, second key and value are K2 and
-V2, and so on.  Then the line:
+Here is an example of plist that is written in the expression
+explained above.
+
 @verbatim
 abc 123 (pqr 0xff) "m\"text" (_\\_ ("string" xyz) -456)
 @endverbatim
-is interpreted as follows.
+
+It represents the following plist:
+
 @verbatim
 (Msymbol:abc,
  Minteger:123,
@@ -94,11 +108,6 @@ is interpreted as follows.
          Minteger:-456))
 @endverbatim
 
-The default database loader of the m17n library actually read a text
-of this syntax from the database file.
-
-Here after we describes the plist format of each data by this syntax.
-
 @section fontenc Font Encoding
 
 The m17n library loads information about the encoding of each font
@@ -107,7 +116,7 @@ format of the data is as follows:
 
 @verbatim
 FONT-ENCODING ::=
-    '(' PER-FONT-INFO * ')'
+    PER-FONT-INFO *
 
 PER-FONT-INFO ::=
     '(' FONT-SPEC ENCODING ')'
@@ -129,14 +138,15 @@ XLFD font name fields.  Omitted symbols are regarded as @c nil, and
 should be applied to all fonts whose family is "alice0 lao", and
 registry is "iso8859-1".
 
-@c ENCODING is a charset symbol.  A font matching @c FONT-SPEC
-supports all characters of the charset, and a character code is mapped
-to the corresponding glyph code of the font by this charset.
+@c ENCODING is a symbol representing a charset.  A font matching @c
+FONT-SPEC supports all characters of the charset, and a character code
+is mapped to the corresponding glyph code of the font by this charset.
+
 
 @section fontsize Font Resizing
 
 In some case, a font contains incorrect information about its size
-(typically in the case of a hacked TrueType font), and results in a
+(typically in the case of a hacked TrueType font), which results in a
 bad text layout when such a font is used in combination with the other
 fonts.  To overcome this problem, the m17n library loads information
 about font-size correction from the m17n database by the tags \<font,
@@ -144,7 +154,7 @@ resize\>.  The plist format of the data is as follows:
 
 @verbatim
 FONT-RESIZE ::=
-    '(' PER-FONT-INFO * ')'
+    PER-FONT-INFO *
 
 PER-FONT-INFO ::=
     '(' FONT-SPEC RESIZE-RATIO ')'
@@ -175,7 +185,7 @@ as follows:
 
 @verbatim
 FONTSET ::=
-    '(' PER-SCRIPT + ')'
+    PER-SCRIPT * PER-CHARSET * FALLBACK *
 
 PER-SCRIPT ::=
     '(' SCRIPT PER-LANGUAGE + ')'
@@ -183,6 +193,12 @@ PER-SCRIPT ::=
 PER-LANGUAGE ::=
     '(' LANGUAGE FONT-SPEC-ELEMENT + ')'
 
+PER-CHARSET ::=
+    '(' CHARSET FONT-SPEC-ELEMENT + ')'
+
+FALLBACK ::=
+    FONT-SPEC-ELEMENT
+
 FONT-SPEC-ELEMENT ::=
     '(' FONT-SPEC [ FLT-NAME ] ')'
 
@@ -192,7 +208,7 @@ FONT-SPEC ::=
     ')'
 @endverbatim    
 
-@c SCRIPT is a symbol of script name (e.g. latin, han), or @c nil.  @c
+@c SCRIPT is a symbol of script name (e.g. latin, han) or @c nil.  @c
 LANGUAGE is a two-letter symbol of language name code defined by ISO
 639 (e.g. ja, zh) or @c nil.  The meanings of @c FOUNDRY to @c
 REGISTRY are the same as @e Font @e Encoding.  @c FLT-NAME is a name
@@ -214,22 +230,22 @@ instructs the rendering engine to use a font of registry
 "jisx0208.1983-0" for a "han" character that has @c Mlanguage text
 propert "ja" if the character is in the repertories of such fonts.
 Otherwise, try a font of registry "gb2312.1980-0" or "big5-0".  If a
-"han" character doesn not have @c Mlangauge text property, try all
+"han" character does not have @c Mlangauge text property, try all
 three fonts.
 
 @section flt Font Layout Table
 
-Usually, the rendering engine converts character codes of a text into
-glyph codes one by one by consulting information about encoding of
-each selected font.  But, for rendering a text that requires
-complicated layouting (e.g. Thai and Indic), such an one to one
-conversion is not sufficient.  In addition, some glyphs must be
-shifted 2-dimensionally on the screen.  For such a case, a font layout
-table (FLT in short) must be used.
-
-A FLT can contain all the information in OpenType Layout Table (CMAP,
-GSUB, and GPOS) in addition to the information about how to extract a
-grapheme cluster and how to re-order characters.
+Usually, the rendering engine converts character codes of into glyph
+codes one by one by consulting information about encoding of each
+selected font.  But, for rendering a text that requires complicated
+layouting (e.g. Thai and Indic), such an one to one conversion is not
+sufficient.  In addition, some glyphs must be shifted 2-dimensionally
+on the screen.  For such a case, a font layout table (FLT in short)
+must be used.
+
+A FLT can contain the information equivarent to OpenType Layout Table
+(CMAP, GSUB, and GPOS) in addition to the information about how to
+extract a grapheme cluster and how to re-order characters.
 
 The m17n library loads a FLT from the m17n database by the tags
 \<font, layouter, FLT-NAME\>.  The plist format of the data is as