@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1998, 1999, 2001, 2002, 2003, 2004,
-@c 2005, 2006, 2007, 2008, 2009 Free Software Foundation, Inc.
+@c Copyright (C) 1998-1999, 2001-2011 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../../info/characters
@node Non-ASCII Characters, Searching and Matching, Text, Top
Emacs buffers and strings support a large repertoire of characters
from many different scripts, allowing users to type and display text
-in most any known written language.
+in almost any known written language.
@cindex character codepoint
@cindex codespace
follows the @dfn{Unicode Standard}. The Unicode Standard assigns a
unique number, called a @dfn{codepoint}, to each and every character.
The range of codepoints defined by Unicode, or the Unicode
-@dfn{codespace}, is @code{0..10FFFF} (in hex), inclusive. Emacs
-extends this range with codepoints in the range @code{110000..3FFFFF},
-which it uses for representing characters that are not unified with
-Unicode and raw 8-bit bytes that cannot be interpreted as characters
-(the latter occupy the range @code{3FFF80..3FFFFF}). Thus, a
-character codepoint in Emacs is a 22-bit integer number.
+@dfn{codespace}, is @code{0..#x10FFFF} (in hexadecimal notation),
+inclusive. Emacs extends this range with codepoints in the range
+@code{#x110000..#x3FFFFF}, which it uses for representing characters
+that are not unified with Unicode and @dfn{raw 8-bit bytes} that
+cannot be interpreted as characters. Thus, a character codepoint in
+Emacs is a 22-bit integer number.
@cindex internal representation of characters
@cindex characters, representation in buffers and strings
The representation for a string is determined and recorded in the string
when the string is constructed.
-@defopt enable-multibyte-characters
+@defvar enable-multibyte-characters
This variable specifies the current buffer's text representation.
If it is non-@code{nil}, the buffer contains multibyte text; otherwise,
it contains unibyte encoded text or binary non-text data.
You cannot set this variable directly; instead, use the function
@code{set-buffer-multibyte} to change a buffer's representation.
-
-The @samp{--unibyte} command line option does its job by setting the
-default value to @code{nil} early in startup.
-@end defopt
+@end defvar
@defun position-bytes position
Buffer positions are measured in character units. This function
user that cannot be overridden automatically.
Converting unibyte text to multibyte text leaves @acronym{ASCII}
-characters unchanged, and converts bytes with codes 128 through 159 to
+characters unchanged, and converts bytes with codes 128 through 255 to
the multibyte representation of raw eight-bit bytes.
Converting multibyte text to unibyte converts all @acronym{ASCII}
it is returned unchanged. The function assumes that @var{string}
includes only @acronym{ASCII} characters and raw 8-bit bytes; the
latter are converted to their multibyte representation corresponding
-to the codepoints in the @code{3FFF80..3FFFFF} area (@pxref{Text
-Representations, codepoints}).
+to the codepoints @code{#x3FFF80} through @code{#x3FFFFF}, inclusive
+(@pxref{Text Representations, codepoints}).
@end defun
@defun string-to-unibyte string
characters.
@end defun
+@defun byte-to-string byte
+@cindex byte to string
+This function returns a unibyte string containing a single byte of
+character data, @var{character}. It signals a error if
+@var{character} is not an integer between 0 and 255.
+@end defun
+
@defun multibyte-char-to-unibyte char
This converts the multibyte character @var{char} to a unibyte
character, and returns that character. If @var{char} is neither
The unibyte and multibyte text representations use different
character codes. The valid character codes for unibyte representation
-range from 0 to 255---the values that can fit in one byte. The valid
-character codes for multibyte representation range from 0 to 4194303
-(#x3FFFFF). In this code space, values 0 through 127 are for
-@acronym{ASCII} characters, and values 128 through 4194175 (#x3FFF7F)
-are for non-@acronym{ASCII} characters. Values 0 through 1114111
-(#10FFFF) correspond to Unicode characters of the same codepoint;
-values 1114112 (#110000) through 4194175 (#x3FFF7F) represent
-characters that are not unified with Unicode; and values 4194176
-(#x3FFF80) through 4194303 (#x3FFFFF) represent eight-bit raw bytes.
+range from 0 to @code{#xFF} (255)---the values that can fit in one
+byte. The valid character codes for multibyte representation range
+from 0 to @code{#x3FFFFF}. In this code space, values 0 through
+@code{#x7F} (127) are for @acronym{ASCII} characters, and values
+@code{#x80} (128) through @code{#x3FFF7F} (4194175) are for
+non-@acronym{ASCII} characters.
+
+ Emacs character codes are a superset of the Unicode standard.
+Values 0 through @code{#x10FFFF} (1114111) correspond to Unicode
+characters of the same codepoint; values @code{#x110000} (1114112)
+through @code{#x3FFF7F} (4194175) represent characters that are not
+unified with Unicode; and values @code{#x3FFF80} (4194176) through
+@code{#x3FFFFF} (4194303) represent eight-bit raw bytes.
@defun characterp charcode
This returns @code{t} if @var{charcode} is a valid character, and
value is a string consisting of upper-case Latin letters A to Z,
digits, spaces, and hyphen @samp{-} characters.
+@cindex unicode general category
@item general-category
This property corresponds to the Unicode @code{General_Category}
property. The value is a symbol whose name is a 2-letter abbreviation
@var{propname} for the character @var{char}.
@end defun
-@defvar char-script-table
+@defvar unicode-category-table
The value of this variable is a char-table (@pxref{Char-Tables}) that
-specifies, for each character, a symbol whose name is the script to
-which the character belongs, according to the Unicode Standard
-classification of the Unicode code space into script-specific blocks.
-This char-table has a single extra slot whose value is the list of all
-script symbols.
+specifies, for each character, its Unicode @code{General_Category}
+property as a symbol.
+@end defvar
+
+@defvar char-script-table
+The value of this variable is a char-table that specifies, for each
+character, a symbol whose name is the script to which the character
+belongs, according to the Unicode Standard classification of the
+Unicode code space into script-specific blocks. This char-table has a
+single extra slot whose value is the list of all script symbols.
@end defvar
@defvar char-width-table
@cindex @code{eight-bit}, a charset
Emacs defines several special character sets. The character set
@code{unicode} includes all the characters whose Emacs code points are
-in the range @code{0..10FFFF}. The character set @code{emacs}
+in the range @code{0..#x10FFFF}. The character set @code{emacs}
includes all @acronym{ASCII} and non-@acronym{ASCII} characters.
Finally, the @code{eight-bit} charset includes the 8-bit raw bytes;
Emacs uses it to represent raw bytes encountered in text.
The following function comes in handy for applying a certain
function to all or part of the characters in a charset:
-@defun map-charset-chars function charset &optional arg from to
+@defun map-charset-chars function charset &optional arg from-code to-code
Call @var{function} for characters in @var{charset}. @var{function}
is called with two arguments. The first one is a cons cell
@code{(@var{from} . @var{to})}, where @var{from} and @var{to}
indicate a range of characters contained in charset. The second
-argument is the optional argument @var{arg}.
+argument passed to @var{function} is @var{arg}.
By default, the range of codepoints passed to @var{function} includes
all the characters in @var{charset}, but optional arguments
@defun make-translation-table-from-vector vec
This function returns a translation table made from @var{vec} that is
-an array of 256 elements to map byte values 0 through 255 to
+an array of 256 elements to map bytes (values 0 through #xFF) to
characters. Elements may be @code{nil} for untranslated bytes. The
returned table has a translation table for reverse mapping in the
first extra slot, and the value @code{1} in the second extra slot.
@vindex select-safe-coding-system-accept-default-p
If the variable @code{select-safe-coding-system-accept-default-p} is
-non-@code{nil}, its value overrides the value of
-@var{accept-default-p}.
+non-@code{nil}, it should be a function taking a single argument.
+It is used in place of @var{accept-default-p}, overriding any
+value supplied for this argument.
As a final step, before returning the chosen coding system,
@code{select-safe-coding-system} checks whether that coding system is
text. They logically consist of a series of byte values; that is, a
series of @acronym{ASCII} and eight-bit characters. In unibyte
buffers and strings, these characters have codes in the range 0
-through 255. In a multibyte buffer or string, eight-bit characters
-have character codes higher than 255 (@pxref{Text Representations}),
-but Emacs transparently converts them to their single-byte values when
-you encode or decode such text.
+through #xFF (255). In a multibyte buffer or string, eight-bit
+characters have character codes higher than #xFF (@pxref{Text
+Representations}), but Emacs transparently converts them to their
+single-byte values when you encode or decode such text.
The usual way to read a file into a buffer as a sequence of bytes, so
you can decode the contents explicitly, is with
@code{locale-coding-system}. @xref{Locales,,, libc, The GNU Libc Manual},
for more information about locales and locale items.
@end defun
-
-@ignore
- arch-tag: be705bf8-941b-4c35-84fc-ad7d20ddb7cb
-@end ignore
HCoop / bpt / emacs.git / blobdiff