@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, 2010 Free Software Foundation, Inc.
+@c Copyright (C) 1998-1999, 2001-2012 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
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}
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 an 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
@code{canonical-combining-class}. However, sometimes we shorten the
names to make their use easier.
+@cindex unassigned character codepoints
+ Some codepoints are left @dfn{unassigned} by the
+@acronym{UCD}---they don't correspond to any character. The Unicode
+Standard defines default values of properties for such codepoints;
+they are mentioned below for each property.
+
Here is the full list of value types for all the character
properties that Emacs knows about:
@table @code
@item name
-This property corresponds to the Unicode @code{Name} property. The
-value is a string consisting of upper-case Latin letters A to Z,
-digits, spaces, and hyphen @samp{-} characters.
+Corresponds to the @code{Name} Unicode property. The value is a
+string consisting of upper-case Latin letters A to Z, digits, spaces,
+and hyphen @samp{-} characters. For unassigned codepoints, the value
+is an empty string.
@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
-of the character's classification.
+Corresponds to the @code{General_Category} Unicode property. The
+value is a symbol whose name is a 2-letter abbreviation of the
+character's classification. For unassigned codepoints, the value
+is @code{Cn}.
@item canonical-combining-class
-Corresponds to the Unicode @code{Canonical_Combining_Class} property.
-The value is an integer number.
+Corresponds to the @code{Canonical_Combining_Class} Unicode property.
+The value is an integer number. For unassigned codepoints, the value
+is zero.
+@cindex bidirectional class of characters
@item bidi-class
Corresponds to the Unicode @code{Bidi_Class} property. The value is a
symbol whose name is the Unicode @dfn{directional type} of the
-character.
+character. Emacs uses this property when it reorders bidirectional
+text for display (@pxref{Bidirectional Display}). For unassigned
+codepoints, the value depends on the code blocks to which the
+codepoint belongs: most unassigned codepoints get the value of
+@code{L} (strong L), but some get values of @code{AL} (Arabic letter)
+or @code{R} (strong R).
@item decomposition
Corresponds to the Unicode @code{Decomposition_Type} and
brackets; e.g., Unicode specifies @samp{<small>} where Emacs uses
@samp{small}.
}; the other elements are characters that give the compatibility
-decomposition sequence of this character.
+decomposition sequence of this character. For unassigned codepoints,
+the value is the character itself.
@item decimal-digit-value
Corresponds to the Unicode @code{Numeric_Value} property for
characters whose @code{Numeric_Type} is @samp{Digit}. The value is an
-integer number.
+integer number. For unassigned codepoints, the value is @code{nil},
+which means @acronym{NaN}, or ``not-a-number''.
-@item digit
+@item digit-value
Corresponds to the Unicode @code{Numeric_Value} property for
characters whose @code{Numeric_Type} is @samp{Decimal}. The value is
an integer number. Examples of such characters include compatibility
subscript and superscript digits, for which the value is the
-corresponding number.
+corresponding number. For unassigned codepoints, the value is
+@code{nil}, which means @acronym{NaN}.
@item numeric-value
Corresponds to the Unicode @code{Numeric_Value} property for
characters that have this property include fractions, subscripts,
superscripts, Roman numerals, currency numerators, and encircled
numbers. For example, the value of this property for the character
-@code{U+2155} (@sc{vulgar fraction one fifth}) is @code{0.2}.
+@code{U+2155} (@sc{vulgar fraction one fifth}) is @code{0.2}. For
+unassigned codepoints, the value is @code{nil}, which means
+@acronym{NaN}.
+@cindex mirroring of characters
@item mirrored
Corresponds to the Unicode @code{Bidi_Mirrored} property. The value
-of this property is a symbol, either @code{Y} or @code{N}.
+of this property is a symbol, either @code{Y} or @code{N}. For
+unassigned codepoints, the value is @code{N}.
+
+@item mirroring
+Corresponds to the Unicode @code{Bidi_Mirroring_Glyph} property. The
+value of this property is a character whose glyph represents the
+mirror image of the character's glyph, or @code{nil} if there's no
+defined mirroring glyph. All the characters whose @code{mirrored}
+property is @code{N} have @code{nil} as their @code{mirroring}
+property; however, some characters whose @code{mirrored} property is
+@code{Y} also have @code{nil} for @code{mirroring}, because no
+appropriate characters exist with mirrored glyphs. Emacs uses this
+property to display mirror images of characters when appropriate
+(@pxref{Bidirectional Display}). For unassigned codepoints, the value
+is @code{nil}.
@item old-name
Corresponds to the Unicode @code{Unicode_1_Name} property. The value
-is a string.
+is a string. For unassigned codepoints, the value is an empty string.
@item iso-10646-comment
Corresponds to the Unicode @code{ISO_Comment} property. The value is
-a string.
+a string. For unassigned codepoints, the value is an empty string.
@item uppercase
Corresponds to the Unicode @code{Simple_Uppercase_Mapping} property.
-The value of this property is a single character.
+The value of this property is a single character. For unassigned
+codepoints, the value is @code{nil}, which means the character itself.
@item lowercase
Corresponds to the Unicode @code{Simple_Lowercase_Mapping} property.
-The value of this property is a single character.
+The value of this property is a single character. For unassigned
+codepoints, the value is @code{nil}, which means the character itself.
@item titlecase
Corresponds to the Unicode @code{Simple_Titlecase_Mapping} property.
@dfn{Title case} is a special form of a character used when the first
character of a word needs to be capitalized. The value of this
-property is a single character.
+property is a single character. For unassigned codepoints, the value
+is @code{nil}, which means the character itself.
@end table
@defun get-char-code-property char propname
@result{} Nd
@end group
@group
-(get-char-code-property ?\u2084 'digit-value) ; subscript 4
+;; subscript 4
+(get-char-code-property ?\u2084 'digit-value)
@result{} 4
@end group
@group
-(get-char-code-property ?\u2155 'numeric-value) ; one fifth
- @result{} 1/5
+;; one fifth
+(get-char-code-property ?\u2155 'numeric-value)
+ @result{} 0.2
@end group
@group
-(get-char-code-property ?\u2163 'numeric-value) ; Roman IV
- @result{} \4
+;; Roman IV
+(get-char-code-property ?\u2163 'numeric-value)
+ @result{} 4
@end group
@end example
@end defun
@var{encoding-system} is the coding system for encoding (in case
@var{operation} does encoding).
-The argument @var{operation} is a symbol, one of @code{write-region},
-@code{start-process}, @code{call-process}, @code{call-process-region},
-@code{insert-file-contents}, or @code{open-network-stream}. These are
-the names of the Emacs I/O primitives that can do character code and
-eol conversion.
+The argument @var{operation} is a symbol; it should be one of
+@code{write-region}, @code{start-process}, @code{call-process},
+@code{call-process-region}, @code{insert-file-contents}, or
+@code{open-network-stream}. These are the names of the Emacs I/O
+primitives that can do character code and eol conversion.
The remaining arguments should be the same arguments that might be given
to the corresponding I/O primitive. Depending on the primitive, one
Sometimes, you need to prefer several coding systems for some
operation, rather than fix a single one. Emacs lets you specify a
priority order for using coding systems. This ordering affects the
-sorting of lists of coding sysems returned by functions such as
+sorting of lists of coding systems returned by functions such as
@code{find-coding-systems-region} (@pxref{Lisp and Coding Systems}).
@defun coding-system-priority-list &optional highestp
@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