@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1998, 1999 Free Software Foundation, Inc.
+@c Copyright (C) 1998, 1999, 2002, 2003, 2004,
+@c 2005, 2006 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
@end defvar
@defun position-bytes position
-@tindex position-bytes
Return the byte-position corresponding to buffer position
@var{position} in the current buffer. This is 1 at the start of the
buffer, and counts upward in bytes. If @var{position} is out of
@end defun
@defun byte-to-position byte-position
-@tindex byte-to-position
Return the buffer position corresponding to byte-position
@var{byte-position} in the current buffer. If @var{byte-position} is
out of range, the value is @code{nil}.
@end defun
@defun charset-plist charset
-@tindex charset-plist
This function returns the charset property list of the character set
@var{charset}. Although @var{charset} is a symbol, this is not the same
as the property list of that symbol. Charset properties are used for
@end defun
@defun charset-bytes charset
-@tindex charset-bytes
This function returns the number of bytes used to represent a character
in character set @var{charset}.
@end defun
@defun charset-after &optional pos
This function return the charset of a character in the current buffer
at position @var{pos}. If @var{pos} is omitted or @code{nil}, it
-defauls to the current value of point. If @var{pos} is out of range,
+defaults to the current value of point. If @var{pos} is out of range,
the value is @code{nil}.
@end defun
@defvar translation-table-for-input
Self-inserting characters are translated through this translation
-table before they are inserted. This variable automatically becomes
-buffer-local when set.
+table before they are inserted. Search commands also translate their
+input through this table, so they can compare more reliably with
+what's in the buffer.
@code{set-buffer-file-coding-system} sets this variable so that your
keyboard input gets translated into the character sets that the buffer
-is likely to contain.
+is likely to contain. This variable automatically becomes
+buffer-local when set.
@end defvar
@node Coding Systems
conversion, but some of them leave the choice unspecified---to be chosen
heuristically for each file, based on the data.
+ In general, a coding system doesn't guarantee roundtrip identity:
+decoding a byte sequence using coding system, then encoding the
+resulting text in the same coding system, can produce a different byte
+sequence. However, the following coding systems do guarantee that the
+byte sequence will be the same as what you originally decoded:
+
+@quotation
+chinese-big5 chinese-iso-8bit cyrillic-iso-8bit emacs-mule
+greek-iso-8bit hebrew-iso-8bit iso-latin-1 iso-latin-2 iso-latin-3
+iso-latin-4 iso-latin-5 iso-latin-8 iso-latin-9 iso-safe
+japanese-iso-8bit japanese-shift-jis korean-iso-8bit raw-text
+@end quotation
+
+ Encoding buffer text and then decoding the result can also fail to
+reproduce the original text. For instance, if you encode Latin-2
+characters with @code{utf-8} and decode the result using the same
+coding system, you'll get Unicode characters (of charset
+@code{mule-unicode-0100-24ff}). If you encode Unicode characters with
+@code{iso-latin-2} and decode the result with the same coding system,
+you'll get Latin-2 characters.
+
@cindex end of line conversion
@dfn{End of line conversion} handles three different conventions used
on various systems for representing end of line in files. The Unix
you will want to find out afterwards which coding system was chosen.
@defvar buffer-file-coding-system
-This variable records the coding system that was used for visiting the
-current buffer. It is used for saving the buffer, and for writing part
+This buffer-local variable records the coding system that was used to visit
+the current buffer. It is used for saving the buffer, and for writing part
of the buffer with @code{write-region}. If the text to be written
cannot be safely encoded using the coding system specified by this
variable, these operations select an alternative encoding by calling
Otherwise it signals an error with condition @code{coding-system-error}.
@end defun
+@cindex EOL conversion
+@cindex end-of-line conversion
+@cindex line end conversion
+@defun coding-system-eol-type coding-system
+This function returns the type of end-of-line (a.k.a.@: @dfn{eol})
+conversion used by @var{coding-system}. If @var{coding-system}
+specifies a certain eol conversion, the return value is an integer 0,
+1, or 2, standing for @code{unix}, @code{dos}, and @code{mac},
+respectively. If @var{coding-system} doesn't specify eol conversion
+explicitly, the return value is a vector of coding systems, each one
+with one of the possible eol conversion types, like this:
+
+@lisp
+(coding-system-eol-type 'latin-1)
+ @result{} [latin-1-unix latin-1-dos latin-1-mac]
+@end lisp
+
+@noindent
+If this function returns a vector, Emacs will decide, as part of the
+text encoding or decoding process, what eol conversion to use. For
+decoding, the end-of-line format of the text is auto-detected, and the
+eol conversion is set to match it (e.g., DOS-style CRLF format will
+imply @code{dos} eol conversion). For encoding, the eol conversion is
+taken from the appropriate default coding system (e.g.,
+@code{default-buffer-file-coding-system} for
+@code{buffer-file-coding-system}), or from the default eol conversion
+appropriate for the underlying platform.
+@end defun
+
@defun coding-system-change-eol-conversion coding-system eol-type
This function returns a coding system which is like @var{coding-system}
except for its eol conversion, which is specified by @code{eol-type}.
return value is just one coding system, the one that is highest in
priority.
-If the region contains only @acronym{ASCII} characters, the value
-is @code{undecided} or @code{(undecided)}, or a variant specifying
+If the region contains only @acronym{ASCII} characters except for such
+ISO-2022 control characters ISO-2022 as @code{ESC}, the value is
+@code{undecided} or @code{(undecided)}, or a variant specifying
end-of-line conversion, if that can be deduced from the text.
@end defun
@var{encoding-system} is the coding system for encoding (in case
@var{operation} does encoding).
-The argument @var{operation} should be a symbol, one of
-@code{insert-file-contents}, @code{write-region}, @code{call-process},
-@code{call-process-region}, @code{start-process}, or
-@code{open-network-stream}. These are the names of the Emacs I/O primitives
-that can do coding system conversion.
+The argument @var{operation} should be a symbol, any one of
+@code{insert-file-contents}, @code{write-region},
+@code{start-process}, @code{call-process}, @code{call-process-region},
+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 that I/O primitive. Depending on the primitive, one of those
-arguments is selected as the @dfn{target}. For example, if
+to the corresponding I/O primitive. Depending on the primitive, one
+of those arguments is selected as the @dfn{target}. For example, if
@var{operation} does file I/O, whichever argument specifies the file
name is the target. For subprocess primitives, the process name is the
target. For @code{open-network-stream}, the target is the service name
or port number.
-This function looks up the target in @code{file-coding-system-alist},
-@code{process-coding-system-alist}, or
-@code{network-coding-system-alist}, depending on @var{operation}.
+Depending on @var{operation}, this function looks up the target in
+@code{file-coding-system-alist}, @code{process-coding-system-alist},
+or @code{network-coding-system-alist}. If the target is found in the
+alist, @code{find-operation-coding-system} returns its association in
+the alist; otherwise it returns @code{nil}.
+
+If @var{operation} is @code{insert-file-contents}, the argument
+corresponding to the target may be a cons cell of the form
+@code{(@var{filename} . @var{buffer})}). In that case, @var{filename}
+is a file name to look up in @code{file-coding-system-alist}, and
+@var{buffer} is a buffer that contains the file's contents (not yet
+decoded). If @code{file-coding-system-alist} specifies a function to
+call for this file, and that function needs to examine the file's
+contents (as it usually does), it should examine the contents of
+@var{buffer} instead of reading the file.
@end defun
@node Specifying Coding Systems
@code{no-conversion}.
Here are the functions to perform explicit encoding or decoding. The
-decoding functions produce sequences of bytes; the encoding functions
+encoding functions produce sequences of bytes; the decoding functions
are meant to operate on sequences of bytes. All of these functions
discard text properties.
how Emacs interacts with these features.
@defvar locale-coding-system
-@tindex locale-coding-system
@cindex keyboard input decoding on X
This variable specifies the coding system to use for decoding system
error messages and---on X Window system only---keyboard input, for
@end defvar
@defvar system-messages-locale
-@tindex system-messages-locale
This variable specifies the locale to use for generating system error
messages. Changing the locale can cause messages to come out in a
different language or in a different orthography. If the variable is
@end defvar
@defvar system-time-locale
-@tindex system-time-locale
This variable specifies the locale to use for formatting time values.
Changing the locale can cause messages to appear according to the
conventions of a different language. If the variable is @code{nil}, the
HCoop / bpt / emacs.git / blobdiff