Foundation instead of in the original English.
\1f
+File: lispref.info, Node: Coding System Properties, Next: Basic Coding System Functions, Prev: EOL Conversion, Up: Coding Systems
+
+Coding System Properties
+------------------------
+
+`mnemonic'
+ String to be displayed in the modeline when this coding system is
+ active.
+
+`eol-type'
+ End-of-line conversion to be used. It should be one of the types
+ listed in *Note EOL Conversion::.
+
+`eol-lf'
+ The coding system which is the same as this one, except that it
+ uses the Unix line-breaking convention.
+
+`eol-crlf'
+ The coding system which is the same as this one, except that it
+ uses the DOS line-breaking convention.
+
+`eol-cr'
+ The coding system which is the same as this one, except that it
+ uses the Macintosh line-breaking convention.
+
+`post-read-conversion'
+ Function called after a file has been read in, to perform the
+ decoding. Called with two arguments, START and END, denoting a
+ region of the current buffer to be decoded.
+
+`pre-write-conversion'
+ Function called before a file is written out, to perform the
+ encoding. Called with two arguments, START and END, denoting a
+ region of the current buffer to be encoded.
+
+ The following additional properties are recognized if TYPE is
+`iso2022':
+
+`charset-g0'
+`charset-g1'
+`charset-g2'
+`charset-g3'
+ The character set initially designated to the G0 - G3 registers.
+ The value should be one of
+
+ * A charset object (designate that character set)
+
+ * `nil' (do not ever use this register)
+
+ * `t' (no character set is initially designated to the
+ register, but may be later on; this automatically sets the
+ corresponding `force-g*-on-output' property)
+
+`force-g0-on-output'
+`force-g1-on-output'
+`force-g2-on-output'
+`force-g3-on-output'
+ If non-`nil', send an explicit designation sequence on output
+ before using the specified register.
+
+`short'
+ If non-`nil', use the short forms `ESC $ @', `ESC $ A', and `ESC $
+ B' on output in place of the full designation sequences `ESC $ (
+ @', `ESC $ ( A', and `ESC $ ( B'.
+
+`no-ascii-eol'
+ If non-`nil', don't designate ASCII to G0 at each end of line on
+ output. Setting this to non-`nil' also suppresses other
+ state-resetting that normally happens at the end of a line.
+
+`no-ascii-cntl'
+ If non-`nil', don't designate ASCII to G0 before control chars on
+ output.
+
+`seven'
+ If non-`nil', use 7-bit environment on output. Otherwise, use
+ 8-bit environment.
+
+`lock-shift'
+ If non-`nil', use locking-shift (SO/SI) instead of single-shift or
+ designation by escape sequence.
+
+`no-iso6429'
+ If non-`nil', don't use ISO6429's direction specification.
+
+`escape-quoted'
+ If non-`nil', literal control characters that are the same as the
+ beginning of a recognized ISO 2022 or ISO 6429 escape sequence (in
+ particular, ESC (0x1B), SO (0x0E), SI (0x0F), SS2 (0x8E), SS3
+ (0x8F), and CSI (0x9B)) are "quoted" with an escape character so
+ that they can be properly distinguished from an escape sequence.
+ (Note that doing this results in a non-portable encoding.) This
+ encoding flag is used for byte-compiled files. Note that ESC is a
+ good choice for a quoting character because there are no escape
+ sequences whose second byte is a character from the Control-0 or
+ Control-1 character sets; this is explicitly disallowed by the ISO
+ 2022 standard.
+
+`input-charset-conversion'
+ A list of conversion specifications, specifying conversion of
+ characters in one charset to another when decoding is performed.
+ Each specification is a list of two elements: the source charset,
+ and the destination charset.
+
+`output-charset-conversion'
+ A list of conversion specifications, specifying conversion of
+ characters in one charset to another when encoding is performed.
+ The form of each specification is the same as for
+ `input-charset-conversion'.
+
+ The following additional properties are recognized (and required) if
+TYPE is `ccl':
+
+`decode'
+ CCL program used for decoding (converting to internal format).
+
+`encode'
+ CCL program used for encoding (converting to external format).
+
+ The following properties are used internally: EOL-CR, EOL-CRLF,
+EOL-LF, and BASE.
+
+\1f
+File: lispref.info, Node: Basic Coding System Functions, Next: Coding System Property Functions, Prev: Coding System Properties, Up: Coding Systems
+
+Basic Coding System Functions
+-----------------------------
+
+ - Function: find-coding-system coding-system-or-name
+ This function retrieves the coding system of the given name.
+
+ If CODING-SYSTEM-OR-NAME is a coding-system object, it is simply
+ returned. Otherwise, CODING-SYSTEM-OR-NAME should be a symbol.
+ If there is no such coding system, `nil' is returned. Otherwise
+ the associated coding system object is returned.
+
+ - Function: get-coding-system name
+ This function retrieves the coding system of the given name. Same
+ as `find-coding-system' except an error is signalled if there is no
+ such coding system instead of returning `nil'.
+
+ - Function: coding-system-list
+ This function returns a list of the names of all defined coding
+ systems.
+
+ - Function: coding-system-name coding-system
+ This function returns the name of the given coding system.
+
+ - Function: coding-system-base coding-system
+ Returns the base coding system (undecided EOL convention) coding
+ system.
+
+ - Function: make-coding-system name type &optional doc-string props
+ This function registers symbol NAME as a coding system.
+
+ TYPE describes the conversion method used and should be one of the
+ types listed in *Note Coding System Types::.
+
+ DOC-STRING is a string describing the coding system.
+
+ PROPS is a property list, describing the specific nature of the
+ character set. Recognized properties are as in *Note Coding
+ System Properties::.
+
+ - Function: copy-coding-system old-coding-system new-name
+ This function copies OLD-CODING-SYSTEM to NEW-NAME. If NEW-NAME
+ does not name an existing coding system, a new one will be created.
+
+ - Function: subsidiary-coding-system coding-system eol-type
+ This function returns the subsidiary coding system of
+ CODING-SYSTEM with eol type EOL-TYPE.
+
+\1f
+File: lispref.info, Node: Coding System Property Functions, Next: Encoding and Decoding Text, Prev: Basic Coding System Functions, Up: Coding Systems
+
+Coding System Property Functions
+--------------------------------
+
+ - Function: coding-system-doc-string coding-system
+ This function returns the doc string for CODING-SYSTEM.
+
+ - Function: coding-system-type coding-system
+ This function returns the type of CODING-SYSTEM.
+
+ - Function: coding-system-property coding-system prop
+ This function returns the PROP property of CODING-SYSTEM.
+
+\1f
+File: lispref.info, Node: Encoding and Decoding Text, Next: Detection of Textual Encoding, Prev: Coding System Property Functions, Up: Coding Systems
+
+Encoding and Decoding Text
+--------------------------
+
+ - Function: decode-coding-region start end coding-system &optional
+ buffer
+ This function decodes the text between START and END which is
+ encoded in CODING-SYSTEM. This is useful if you've read in
+ encoded text from a file without decoding it (e.g. you read in a
+ JIS-formatted file but used the `binary' or `no-conversion' coding
+ system, so that it shows up as `^[$B!<!+^[(B'). The length of the
+ encoded text is returned. BUFFER defaults to the current buffer
+ if unspecified.
+
+ - Function: encode-coding-region start end coding-system &optional
+ buffer
+ This function encodes the text between START and END using
+ CODING-SYSTEM. This will, for example, convert Japanese
+ characters into stuff such as `^[$B!<!+^[(B' if you use the JIS
+ encoding. The length of the encoded text is returned. BUFFER
+ defaults to the current buffer if unspecified.
+
+\1f
+File: lispref.info, Node: Detection of Textual Encoding, Next: Big5 and Shift-JIS Functions, Prev: Encoding and Decoding Text, Up: Coding Systems
+
+Detection of Textual Encoding
+-----------------------------
+
+ - Function: coding-category-list
+ This function returns a list of all recognized coding categories.
+
+ - Function: set-coding-priority-list list
+ This function changes the priority order of the coding categories.
+ LIST should be a list of coding categories, in descending order of
+ priority. Unspecified coding categories will be lower in priority
+ than all specified ones, in the same relative order they were in
+ previously.
+
+ - Function: coding-priority-list
+ This function returns a list of coding categories in descending
+ order of priority.
+
+ - Function: set-coding-category-system coding-category coding-system
+ This function changes the coding system associated with a coding
+ category.
+
+ - Function: coding-category-system coding-category
+ This function returns the coding system associated with a coding
+ category.
+
+ - Function: detect-coding-region start end &optional buffer
+ This function detects coding system of the text in the region
+ between START and END. Returned value is a list of possible coding
+ systems ordered by priority. If only ASCII characters are found,
+ it returns `autodetect' or one of its subsidiary coding systems
+ according to a detected end-of-line type. Optional arg BUFFER
+ defaults to the current buffer.
+
+\1f
+File: lispref.info, Node: Big5 and Shift-JIS Functions, Next: Predefined Coding Systems, Prev: Detection of Textual Encoding, Up: Coding Systems
+
+Big5 and Shift-JIS Functions
+----------------------------
+
+ These are special functions for working with the non-standard
+Shift-JIS and Big5 encodings.
+
+ - Function: decode-shift-jis-char code
+ This function decodes a JIS X 0208 character of Shift-JIS
+ coding-system. CODE is the character code in Shift-JIS as a cons
+ of type bytes. The corresponding character is returned.
+
+ - Function: encode-shift-jis-char character
+ This function encodes a JIS X 0208 character CHARACTER to
+ SHIFT-JIS coding-system. The corresponding character code in
+ SHIFT-JIS is returned as a cons of two bytes.
+
+ - Function: decode-big5-char code
+ This function decodes a Big5 character CODE of BIG5 coding-system.
+ CODE is the character code in BIG5. The corresponding character
+ is returned.
+
+ - Function: encode-big5-char character
+ This function encodes the Big5 character CHARACTER to BIG5
+ coding-system. The corresponding character code in Big5 is
+ returned.
+
+\1f
+File: lispref.info, Node: Predefined Coding Systems, Prev: Big5 and Shift-JIS Functions, Up: Coding Systems
+
+Coding Systems Implemented
+--------------------------
+
+ MULE initializes most of the commonly used coding systems at XEmacs's
+startup. A few others are initialized only when the relevant language
+environment is selected and support libraries are loaded. (NB: The
+following list is based on XEmacs 21.2.19, the development branch at the
+time of writing. The list may be somewhat different for other
+versions. Recent versions of GNU Emacs 20 implement a few more rare
+coding systems; work is being done to port these to XEmacs.)
+
+ Unfortunately, there is not a consistent naming convention for
+character sets, and for practical purposes coding systems often take
+their name from their principal character sets (ASCII, KOI8-R, Shift
+JIS). Others take their names from the coding system (ISO-2022-JP,
+EUC-KR), and a few from their non-text usages (internal, binary). To
+provide for this, and for the fact that many coding systems have
+several common names, an aliasing system is provided. Finally, some
+effort has been made to use names that are registered as MIME charsets
+(this is why the name 'shift_jis contains that un-Lisp-y underscore).
+
+ There is a systematic naming convention regarding end-of-line (EOL)
+conventions for different systems. A coding system whose name ends in
+"-unix" forces the assumptions that lines are broken by newlines (0x0A).
+A coding system whose name ends in "-mac" forces the assumptions that
+lines are broken by ASCII CRs (0x0D). A coding system whose name ends
+in "-dos" forces the assumptions that lines are broken by CRLF sequences
+(0x0D 0x0A). These subsidiary coding systems are automatically derived
+from a base coding system. Use of the base coding system implies
+autodetection of the text file convention. (The fact that the -unix,
+-mac, and -dos are derived from a base system results in them showing up
+as "aliases" in `list-coding-systems'.) These subsidiaries have a
+consistent modeline indicator as well. "-dos" coding systems have ":T"
+appended to their modeline indicator, while "-mac" coding systems have
+":t" appended (eg, "ISO8:t" for iso-2022-8-mac).
+
+ In the following table, each coding system is given with its mode
+line indicator in parentheses. Non-textual coding systems are listed
+first, followed by textual coding systems and their aliases. (The
+coding system subsidiary modeline indicators ":T" and ":t" will be
+omitted from the table of coding systems.)
+
+ ### SJT 1999-08-23 Maybe should order these by language? Definitely
+need language usage for the ISO-8859 family.
+
+ Note that although true coding system aliases have been implemented
+for XEmacs 21.2, the coding system initialization has not yet been
+converted as of 21.2.19. So coding systems described as aliases have
+the same properties as the aliased coding system, but will not be equal
+as Lisp objects.
+
+`automatic-conversion'
+`undecided'
+`undecided-dos'
+`undecided-mac'
+`undecided-unix'
+ Modeline indicator: `Auto'. A type `undecided' coding system.
+ Attempts to determine an appropriate coding system from file
+ contents or the environment.
+
+`raw-text'
+`no-conversion'
+`raw-text-dos'
+`raw-text-mac'
+`raw-text-unix'
+`no-conversion-dos'
+`no-conversion-mac'
+`no-conversion-unix'
+ Modeline indicator: `Raw'. A type `no-conversion' coding system,
+ which converts only line-break-codes. An implementation quirk
+ means that this coding system is also used for ISO8859-1.
+
+`binary'
+ Modeline indicator: `Binary'. A type `no-conversion' coding
+ system which does no character coding or EOL conversions. An
+ alias for `raw-text-unix'.
+
+`alternativnyj'
+`alternativnyj-dos'
+`alternativnyj-mac'
+`alternativnyj-unix'
+ Modeline indicator: `Cy.Alt'. A type `ccl' coding system used for
+ Alternativnyj, an encoding of the Cyrillic alphabet.
+
+`big5'
+`big5-dos'
+`big5-mac'
+`big5-unix'
+ Modeline indicator: `Zh/Big5'. A type `big5' coding system used
+ for BIG5, the most common encoding of traditional Chinese as used
+ in Taiwan.
+
+`cn-gb-2312'
+`cn-gb-2312-dos'
+`cn-gb-2312-mac'
+`cn-gb-2312-unix'
+ Modeline indicator: `Zh-GB/EUC'. A type `iso2022' coding system
+ used for simplified Chinese (as used in the People's Republic of
+ China), with the `ascii' (G0), `chinese-gb2312' (G1), and `sisheng'
+ (G2) character sets initially designated. Chinese EUC (Extended
+ Unix Code).
+
+`ctext-hebrew'
+`ctext-hebrew-dos'
+`ctext-hebrew-mac'
+`ctext-hebrew-unix'
+ Modeline indicator: `CText/Hbrw'. A type `iso2022' coding system
+ with the `ascii' (G0) and `hebrew-iso8859-8' (G1) character sets
+ initially designated for Hebrew.
+
+`ctext'
+`ctext-dos'
+`ctext-mac'
+`ctext-unix'
+ Modeline indicator: `CText'. A type `iso2022' 8-bit coding system
+ with the `ascii' (G0) and `latin-iso8859-1' (G1) character sets
+ initially designated. X11 Compound Text Encoding. Often
+ mistakenly recognized instead of EUC encodings; usual cause is
+ inappropriate setting of `coding-priority-list'.
+
+`escape-quoted'
+ Modeline indicator: `ESC/Quot'. A type `iso2022' 8-bit coding
+ system with the `ascii' (G0) and `latin-iso8859-1' (G1) character
+ sets initially designated and escape quoting. Unix EOL conversion
+ (ie, no conversion). It is used for .ELC files.
+
+`euc-jp'
+`euc-jp-dos'
+`euc-jp-mac'
+`euc-jp-unix'
+ Modeline indicator: `Ja/EUC'. A type `iso2022' 8-bit coding system
+ with `ascii' (G0), `japanese-jisx0208' (G1), `katakana-jisx0201'
+ (G2), and `japanese-jisx0212' (G3) initially designated. Japanese
+ EUC (Extended Unix Code).
+
+`euc-kr'
+`euc-kr-dos'
+`euc-kr-mac'
+`euc-kr-unix'
+ Modeline indicator: `ko/EUC'. A type `iso2022' 8-bit coding system
+ with `ascii' (G0) and `korean-ksc5601' (G1) initially designated.
+ Korean EUC (Extended Unix Code).
+
+`hz-gb-2312'
+ Modeline indicator: `Zh-GB/Hz'. A type `no-conversion' coding
+ system with Unix EOL convention (ie, no conversion) using
+ post-read-decode and pre-write-encode functions to translate the
+ Hz/ZW coding system used for Chinese.
+
+`iso-2022-7bit'
+`iso-2022-7bit-unix'
+`iso-2022-7bit-dos'
+`iso-2022-7bit-mac'
+`iso-2022-7'
+ Modeline indicator: `ISO7'. A type `iso2022' 7-bit coding system
+ with `ascii' (G0) initially designated. Other character sets must
+ be explicitly designated to be used.
+
+`iso-2022-7bit-ss2'
+`iso-2022-7bit-ss2-dos'
+`iso-2022-7bit-ss2-mac'
+`iso-2022-7bit-ss2-unix'
+ Modeline indicator: `ISO7/SS'. A type `iso2022' 7-bit coding
+ system with `ascii' (G0) initially designated. Other character
+ sets must be explicitly designated to be used. SS2 is used to
+ invoke a 96-charset, one character at a time.
+
+`iso-2022-8'
+`iso-2022-8-dos'
+`iso-2022-8-mac'
+`iso-2022-8-unix'
+ Modeline indicator: `ISO8'. A type `iso2022' 8-bit coding system
+ with `ascii' (G0) and `latin-iso8859-1' (G1) initially designated.
+ Other character sets must be explicitly designated to be used.
+ No single-shift or locking-shift.
+
+`iso-2022-8bit-ss2'
+`iso-2022-8bit-ss2-dos'
+`iso-2022-8bit-ss2-mac'
+`iso-2022-8bit-ss2-unix'
+ Modeline indicator: `ISO8/SS'. A type `iso2022' 8-bit coding
+ system with `ascii' (G0) and `latin-iso8859-1' (G1) initially
+ designated. Other character sets must be explicitly designated to
+ be used. SS2 is used to invoke a 96-charset, one character at a
+ time.
+
+`iso-2022-int-1'
+`iso-2022-int-1-dos'
+`iso-2022-int-1-mac'
+`iso-2022-int-1-unix'
+ Modeline indicator: `INT-1'. A type `iso2022' 7-bit coding system
+ with `ascii' (G0) and `korean-ksc5601' (G1) initially designated.
+ ISO-2022-INT-1.
+
+`iso-2022-jp-1978-irv'
+`iso-2022-jp-1978-irv-dos'
+`iso-2022-jp-1978-irv-mac'
+`iso-2022-jp-1978-irv-unix'
+ Modeline indicator: `Ja-78/7bit'. A type `iso2022' 7-bit coding
+ system. For compatibility with old Japanese terminals; if you
+ need to know, look at the source.
+
+`iso-2022-jp'
+`iso-2022-jp-2 (ISO7/SS)'
+`iso-2022-jp-dos'
+`iso-2022-jp-mac'
+`iso-2022-jp-unix'
+`iso-2022-jp-2-dos'
+`iso-2022-jp-2-mac'
+`iso-2022-jp-2-unix'
+ Modeline indicator: `MULE/7bit'. A type `iso2022' 7-bit coding
+ system with `ascii' (G0) initially designated, and complex
+ specifications to insure backward compatibility with old Japanese
+ systems. Used for communication with mail and news in Japan. The
+ "-2" versions also use SS2 to invoke a 96-charset one character at
+ a time.
+
+`iso-2022-kr'
+ Modeline indicator: `Ko/7bit' A type `iso2022' 7-bit coding
+ system with `ascii' (G0) and `korean-ksc5601' (G1) initially
+ designated. Used for e-mail in Korea.
+
+`iso-2022-lock'
+`iso-2022-lock-dos'
+`iso-2022-lock-mac'
+`iso-2022-lock-unix'
+ Modeline indicator: `ISO7/Lock'. A type `iso2022' 7-bit coding
+ system with `ascii' (G0) initially designated, using Locking-Shift
+ to invoke a 96-charset.
+
+`iso-8859-1'
+`iso-8859-1-dos'
+`iso-8859-1-mac'
+`iso-8859-1-unix'
+ Due to implementation, this is not a type `iso2022' coding system,
+ but rather an alias for the `raw-text' coding system.
+
+`iso-8859-2'
+`iso-8859-2-dos'
+`iso-8859-2-mac'
+`iso-8859-2-unix'
+ Modeline indicator: `MIME/Ltn-2'. A type `iso2022' coding system
+ with `ascii' (G0) and `latin-iso8859-2' (G1) initially invoked.
+
+`iso-8859-3'
+`iso-8859-3-dos'
+`iso-8859-3-mac'
+`iso-8859-3-unix'
+ Modeline indicator: `MIME/Ltn-3'. A type `iso2022' coding system
+ with `ascii' (G0) and `latin-iso8859-3' (G1) initially invoked.
+
+`iso-8859-4'
+`iso-8859-4-dos'
+`iso-8859-4-mac'
+`iso-8859-4-unix'
+ Modeline indicator: `MIME/Ltn-4'. A type `iso2022' coding system
+ with `ascii' (G0) and `latin-iso8859-4' (G1) initially invoked.
+
+`iso-8859-5'
+`iso-8859-5-dos'
+`iso-8859-5-mac'
+`iso-8859-5-unix'
+ Modeline indicator: `ISO8/Cyr'. A type `iso2022' coding system
+ with `ascii' (G0) and `cyrillic-iso8859-5' (G1) initially invoked.
+
+`iso-8859-7'
+`iso-8859-7-dos'
+`iso-8859-7-mac'
+`iso-8859-7-unix'
+ Modeline indicator: `Grk'. A type `iso2022' coding system with
+ `ascii' (G0) and `greek-iso8859-7' (G1) initially invoked.
+
+`iso-8859-8'
+`iso-8859-8-dos'
+`iso-8859-8-mac'
+`iso-8859-8-unix'
+ Modeline indicator: `MIME/Hbrw'. A type `iso2022' coding system
+ with `ascii' (G0) and `hebrew-iso8859-8' (G1) initially invoked.
+
+`iso-8859-9'
+`iso-8859-9-dos'
+`iso-8859-9-mac'
+`iso-8859-9-unix'
+ Modeline indicator: `MIME/Ltn-5'. A type `iso2022' coding system
+ with `ascii' (G0) and `latin-iso8859-9' (G1) initially invoked.
+
+`koi8-r'
+`koi8-r-dos'
+`koi8-r-mac'
+`koi8-r-unix'
+ Modeline indicator: `KOI8'. A type `ccl' coding-system used for
+ KOI8-R, an encoding of the Cyrillic alphabet.
+
+`shift_jis'
+`shift_jis-dos'
+`shift_jis-mac'
+`shift_jis-unix'
+ Modeline indicator: `Ja/SJIS'. A type `shift-jis' coding-system
+ implementing the Shift-JIS encoding for Japanese. The underscore
+ is to conform to the MIME charset implementing this encoding.
+
+`tis-620'
+`tis-620-dos'
+`tis-620-mac'
+`tis-620-unix'
+ Modeline indicator: `TIS620'. A type `ccl' encoding for Thai. The
+ external encoding is defined by TIS620, the internal encoding is
+ peculiar to MULE, and called `thai-xtis'.
+
+`viqr'
+ Modeline indicator: `VIQR'. A type `no-conversion' coding system
+ with Unix EOL convention (ie, no conversion) using
+ post-read-decode and pre-write-encode functions to translate the
+ VIQR coding system for Vietnamese.
+
+`viscii'
+`viscii-dos'
+`viscii-mac'
+`viscii-unix'
+ Modeline indicator: `VISCII'. A type `ccl' coding-system used for
+ VISCII 1.1 for Vietnamese. Differs slightly from VSCII; VISCII is
+ given priority by XEmacs.
+
+`vscii'
+`vscii-dos'
+`vscii-mac'
+`vscii-unix'
+ Modeline indicator: `VSCII'. A type `ccl' coding-system used for
+ VSCII 1.1 for Vietnamese. Differs slightly from VISCII, which is
+ given priority by XEmacs. Use `(prefer-coding-system
+ 'vietnamese-vscii)' to give priority to VSCII.
+
+\1f
+File: lispref.info, Node: CCL, Next: Category Tables, Prev: Coding Systems, Up: MULE
+
+CCL
+===
+
+ CCL (Code Conversion Language) is a simple structured programming
+language designed for character coding conversions. A CCL program is
+compiled to CCL code (represented by a vector of integers) and executed
+by the CCL interpreter embedded in Emacs. The CCL interpreter
+implements a virtual machine with 8 registers called `r0', ..., `r7', a
+number of control structures, and some I/O operators. Take care when
+using registers `r0' (used in implicit "set" statements) and especially
+`r7' (used internally by several statements and operations, especially
+for multiple return values and I/O operations).
+
+ CCL is used for code conversion during process I/O and file I/O for
+non-ISO2022 coding systems. (It is the only way for a user to specify a
+code conversion function.) It is also used for calculating the code
+point of an X11 font from a character code. However, since CCL is
+designed as a powerful programming language, it can be used for more
+generic calculation where efficiency is demanded. A combination of
+three or more arithmetic operations can be calculated faster by CCL than
+by Emacs Lisp.
+
+ *Warning:* The code in `src/mule-ccl.c' and
+`$packages/lisp/mule-base/mule-ccl.el' is the definitive description of
+CCL's semantics. The previous version of this section contained
+several typos and obsolete names left from earlier versions of MULE,
+and many may remain. (I am not an experienced CCL programmer; the few
+who know CCL well find writing English painful.)
+
+ A CCL program transforms an input data stream into an output data
+stream. The input stream, held in a buffer of constant bytes, is left
+unchanged. The buffer may be filled by an external input operation,
+taken from an Emacs buffer, or taken from a Lisp string. The output
+buffer is a dynamic array of bytes, which can be written by an external
+output operation, inserted into an Emacs buffer, or returned as a Lisp
+string.
+
+ A CCL program is a (Lisp) list containing two or three members. The
+first member is the "buffer magnification", which indicates the
+required minimum size of the output buffer as a multiple of the input
+buffer. It is followed by the "main block" which executes while there
+is input remaining, and an optional "EOF block" which is executed when
+the input is exhausted. Both the main block and the EOF block are CCL
+blocks.
+
+ A "CCL block" is either a CCL statement or list of CCL statements.
+A "CCL statement" is either a "set statement" (either an integer or an
+"assignment", which is a list of a register to receive the assignment,
+an assignment operator, and an expression) or a "control statement" (a
+list starting with a keyword, whose allowable syntax depends on the
+keyword).
+
+* Menu:
+
+* CCL Syntax:: CCL program syntax in BNF notation.
+* CCL Statements:: Semantics of CCL statements.
+* CCL Expressions:: Operators and expressions in CCL.
+* Calling CCL:: Running CCL programs.
+* CCL Examples:: The encoding functions for Big5 and KOI-8.
+
+\1f
+File: lispref.info, Node: CCL Syntax, Next: CCL Statements, Up: CCL
+
+CCL Syntax
+----------
+
+ The full syntax of a CCL program in BNF notation:
+
+CCL_PROGRAM :=
+ (BUFFER_MAGNIFICATION
+ CCL_MAIN_BLOCK
+ [ CCL_EOF_BLOCK ])
+
+BUFFER_MAGNIFICATION := integer
+CCL_MAIN_BLOCK := CCL_BLOCK
+CCL_EOF_BLOCK := CCL_BLOCK
+
+CCL_BLOCK :=
+ STATEMENT | (STATEMENT [STATEMENT ...])
+STATEMENT :=
+ SET | IF | BRANCH | LOOP | REPEAT | BREAK | READ | WRITE
+ | CALL | END
+
+SET :=
+ (REG = EXPRESSION)
+ | (REG ASSIGNMENT_OPERATOR EXPRESSION)
+ | integer
+
+EXPRESSION := ARG | (EXPRESSION OPERATOR ARG)
+
+IF := (if EXPRESSION CCL_BLOCK [CCL_BLOCK])
+BRANCH := (branch EXPRESSION CCL_BLOCK [CCL_BLOCK ...])
+LOOP := (loop STATEMENT [STATEMENT ...])
+BREAK := (break)
+REPEAT :=
+ (repeat)
+ | (write-repeat [REG | integer | string])
+ | (write-read-repeat REG [integer | ARRAY])
+READ :=
+ (read REG ...)
+ | (read-if (REG OPERATOR ARG) CCL_BLOCK CCL_BLOCK)
+ | (read-branch REG CCL_BLOCK [CCL_BLOCK ...])
+WRITE :=
+ (write REG ...)
+ | (write EXPRESSION)
+ | (write integer) | (write string) | (write REG ARRAY)
+ | string
+CALL := (call ccl-program-name)
+END := (end)
+
+REG := r0 | r1 | r2 | r3 | r4 | r5 | r6 | r7
+ARG := REG | integer
+OPERATOR :=
+ + | - | * | / | % | & | '|' | ^ | << | >> | <8 | >8 | //
+ | < | > | == | <= | >= | != | de-sjis | en-sjis
+ASSIGNMENT_OPERATOR :=
+ += | -= | *= | /= | %= | &= | '|=' | ^= | <<= | >>=
+ARRAY := '[' integer ... ']'
+
+\1f
+File: lispref.info, Node: CCL Statements, Next: CCL Expressions, Prev: CCL Syntax, Up: CCL
+
+CCL Statements
+--------------
+
+ The Emacs Code Conversion Language provides the following statement
+types: "set", "if", "branch", "loop", "repeat", "break", "read",
+"write", "call", and "end".
+
+Set statement:
+==============
+
+ The "set" statement has three variants with the syntaxes `(REG =
+EXPRESSION)', `(REG ASSIGNMENT_OPERATOR EXPRESSION)', and `INTEGER'.
+The assignment operator variation of the "set" statement works the same
+way as the corresponding C expression statement does. The assignment
+operators are `+=', `-=', `*=', `/=', `%=', `&=', `|=', `^=', `<<=',
+and `>>=', and they have the same meanings as in C. A "naked integer"
+INTEGER is equivalent to a SET statement of the form `(r0 = INTEGER)'.
+
+I/O statements:
+===============
+
+ The "read" statement takes one or more registers as arguments. It
+reads one byte (a C char) from the input into each register in turn.
+
+ The "write" takes several forms. In the form `(write REG ...)' it
+takes one or more registers as arguments and writes each in turn to the
+output. The integer in a register (interpreted as an Emchar) is
+encoded to multibyte form (ie, Bufbytes) and written to the current
+output buffer. If it is less than 256, it is written as is. The forms
+`(write EXPRESSION)' and `(write INTEGER)' are treated analogously.
+The form `(write STRING)' writes the constant string to the output. A
+"naked string" `STRING' is equivalent to the statement `(write
+STRING)'. The form `(write REG ARRAY)' writes the REGth element of the
+ARRAY to the output.
+
+Conditional statements:
+=======================
+
+ The "if" statement takes an EXPRESSION, a CCL BLOCK, and an optional
+SECOND CCL BLOCK as arguments. If the EXPRESSION evaluates to
+non-zero, the first CCL BLOCK is executed. Otherwise, if there is a
+SECOND CCL BLOCK, it is executed.
+
+ The "read-if" variant of the "if" statement takes an EXPRESSION, a
+CCL BLOCK, and an optional SECOND CCL BLOCK as arguments. The
+EXPRESSION must have the form `(REG OPERATOR OPERAND)' (where OPERAND is
+a register or an integer). The `read-if' statement first reads from
+the input into the first register operand in the EXPRESSION, then
+conditionally executes a CCL block just as the `if' statement does.
+
+ The "branch" statement takes an EXPRESSION and one or more CCL
+blocks as arguments. The CCL blocks are treated as a zero-indexed
+array, and the `branch' statement uses the EXPRESSION as the index of
+the CCL block to execute. Null CCL blocks may be used as no-ops,
+continuing execution with the statement following the `branch'
+statement in the containing CCL block. Out-of-range values for the
+EXPRESSION are also treated as no-ops.
+
+ The "read-branch" variant of the "branch" statement takes an
+REGISTER, a CCL BLOCK, and an optional SECOND CCL BLOCK as arguments.
+The `read-branch' statement first reads from the input into the
+REGISTER, then conditionally executes a CCL block just as the `branch'
+statement does.
+
+Loop control statements:
+========================
+
+ The "loop" statement creates a block with an implied jump from the
+end of the block back to its head. The loop is exited on a `break'
+statement, and continued without executing the tail by a `repeat'
+statement.
+
+ The "break" statement, written `(break)', terminates the current
+loop and continues with the next statement in the current block.
+
+ The "repeat" statement has three variants, `repeat', `write-repeat',
+and `write-read-repeat'. Each continues the current loop from its
+head, possibly after performing I/O. `repeat' takes no arguments and
+does no I/O before jumping. `write-repeat' takes a single argument (a
+register, an integer, or a string), writes it to the output, then jumps.
+`write-read-repeat' takes one or two arguments. The first must be a
+register. The second may be an integer or an array; if absent, it is
+implicitly set to the first (register) argument. `write-read-repeat'
+writes its second argument to the output, then reads from the input
+into the register, and finally jumps. See the `write' and `read'
+statements for the semantics of the I/O operations for each type of
+argument.
+
+Other control statements:
+=========================
+
+ The "call" statement, written `(call CCL-PROGRAM-NAME)', executes a
+CCL program as a subroutine. It does not return a value to the caller,
+but can modify the register status.
+
+ The "end" statement, written `(end)', terminates the CCL program
+successfully, and returns to caller (which may be a CCL program). It
+does not alter the status of the registers.
+
+\1f
File: lispref.info, Node: CCL Expressions, Next: Calling CCL, Prev: CCL Statements, Up: CCL
CCL Expressions
side-effect) to contain the ending values for the corresponding
registers and IC.
- - Function: ccl-execute-on-string ccl-program status str &optional
+ - Function: ccl-execute-on-string ccl-program status string &optional
continue
Execute CCL-PROGRAM with initial STATUS on STRING. CCL-PROGRAM is
a vector of compiled CCL code created by `ccl-compile'. STATUS
`nil' value for a register initializer causes the register to be
set to 0. A `nil' value for the IC initializer causes execution
to start at the beginning of the program. An optional fourth
- argument CONTINUE, if non-nil, causes the IC to remain on the
+ argument CONTINUE, if non-`nil', causes the IC to remain on the
unsatisfied read operation if the program terminates due to
exhaustion of the input buffer. Otherwise the IC is set to the end
of the program. When the program is done, STATUS is modified (by
registered:
- Function: register-ccl-program name ccl-program
- Register NAME for CCL program PROGRAM in `ccl-program-table'.
- PROGRAM should be the compiled form of a CCL program, or nil.
- Return index number of the registered CCL program.
+ Register NAME for CCL program CCL-PROGRAM in `ccl-program-table'.
+ CCL-PROGRAM should be the compiled form of a CCL program, or
+ `nil'. Return index number of the registered CCL program.
Information about the processor time used by the CCL interpreter can
be obtained using these functions:
Special Lisp functions are provided that abstract this, so you do not
have to directly manipulate bit vectors.
- - Function: category-table-p obj
- This function returns `t' if ARG is a category table.
+ - Function: category-table-p object
+ This function returns `t' if OBJECT is a category table.
- Function: category-table &optional buffer
This function returns the current category table. This is the one
This function returns the standard category table. This is the
one used for new buffers.
- - Function: copy-category-table &optional table
- This function constructs a new category table and return it. It
- is a copy of the TABLE, which defaults to the standard category
- table.
+ - Function: copy-category-table &optional category-table
+ This function returns a new category table which is a copy of
+ CATEGORY-TABLE, which defaults to the standard category table.
- - Function: set-category-table table &optional buffer
- This function selects a new category table for BUFFER. One
- argument, a category table. BUFFER defaults to the current buffer
- if omitted.
+ - Function: set-category-table category-table &optional buffer
+ This function selects CATEGORY-TABLE as the new category table for
+ BUFFER. BUFFER defaults to the current buffer if omitted.
- - Function: category-designator-p obj
- This function returns `t' if ARG is a category designator (a char
- in the range `' '' to `'~'').
+ - Function: category-designator-p object
+ This function returns `t' if OBJECT is a category designator (a
+ char in the range `' '' to `'~'').
- - Function: category-table-value-p obj
- This function returns `t' if ARG is a category table value. Valid
- values are `nil' or a bit vector of size 95.
+ - Function: category-table-value-p object
+ This function returns `t' if OBJECT is a category table value.
+ Valid values are `nil' or a bit vector of size 95.
\1f
File: lispref.info, Node: Tips, Next: Building XEmacs and Object Allocation, Prev: MULE, Up: Top
* Comment Tips:: Conventions for writing comments.
* Library Headers:: Standard headers for library packages.
-\1f
-File: lispref.info, Node: Style Tips, Next: Compilation Tips, Up: Tips
-
-Writing Clean Lisp Programs
-===========================
-
- Here are some tips for avoiding common errors in writing Lisp code
-intended for widespread use:
-
- * Since all global variables share the same name space, and all
- functions share another name space, you should choose a short word
- to distinguish your program from other Lisp programs. Then take
- care to begin the names of all global variables, constants, and
- functions with the chosen prefix. This helps avoid name conflicts.
-
- This recommendation applies even to names for traditional Lisp
- primitives that are not primitives in XEmacs Lisp--even to `cadr'.
- Believe it or not, there is more than one plausible way to define
- `cadr'. Play it safe; append your name prefix to produce a name
- like `foo-cadr' or `mylib-cadr' instead.
-
- If you write a function that you think ought to be added to Emacs
- under a certain name, such as `twiddle-files', don't call it by
- that name in your program. Call it `mylib-twiddle-files' in your
- program, and send mail to `bug-gnu-emacs@prep.ai.mit.edu'
- suggesting we add it to Emacs. If and when we do, we can change
- the name easily enough.
-
- If one prefix is insufficient, your package may use two or three
- alternative common prefixes, so long as they make sense.
-
- Separate the prefix from the rest of the symbol name with a hyphen,
- `-'. This will be consistent with XEmacs itself and with most
- Emacs Lisp programs.
-
- * It is often useful to put a call to `provide' in each separate
- library program, at least if there is more than one entry point to
- the program.
-
- * If a file requires certain other library programs to be loaded
- beforehand, then the comments at the beginning of the file should
- say so. Also, use `require' to make sure they are loaded.
-
- * If one file FOO uses a macro defined in another file BAR, FOO
- should contain this expression before the first use of the macro:
-
- (eval-when-compile (require 'BAR))
-
- (And BAR should contain `(provide 'BAR)', to make the `require'
- work.) This will cause BAR to be loaded when you byte-compile
- FOO. Otherwise, you risk compiling FOO without the necessary
- macro loaded, and that would produce compiled code that won't work
- right. *Note Compiling Macros::.
-
- Using `eval-when-compile' avoids loading BAR when the compiled
- version of FOO is _used_.
-
- * If you define a major mode, make sure to run a hook variable using
- `run-hooks', just as the existing major modes do. *Note Hooks::.
-
- * If the purpose of a function is to tell you whether a certain
- condition is true or false, give the function a name that ends in
- `p'. If the name is one word, add just `p'; if the name is
- multiple words, add `-p'. Examples are `framep' and
- `frame-live-p'.
-
- * If a user option variable records a true-or-false condition, give
- it a name that ends in `-flag'.
-
- * Please do not define `C-c LETTER' as a key in your major modes.
- These sequences are reserved for users; they are the *only*
- sequences reserved for users, so we cannot do without them.
-
- Instead, define sequences consisting of `C-c' followed by a
- non-letter. These sequences are reserved for major modes.
-
- Changing all the major modes in Emacs 18 so they would follow this
- convention was a lot of work. Abandoning this convention would
- make that work go to waste, and inconvenience users.
-
- * Sequences consisting of `C-c' followed by `{', `}', `<', `>', `:'
- or `;' are also reserved for major modes.
-
- * Sequences consisting of `C-c' followed by any other punctuation
- character are allocated for minor modes. Using them in a major
- mode is not absolutely prohibited, but if you do that, the major
- mode binding may be shadowed from time to time by minor modes.
-
- * You should not bind `C-h' following any prefix character (including
- `C-c'). If you don't bind `C-h', it is automatically available as
- a help character for listing the subcommands of the prefix
- character.
-
- * You should not bind a key sequence ending in <ESC> except following
- another <ESC>. (That is, it is ok to bind a sequence ending in
- `<ESC> <ESC>'.)
-
- The reason for this rule is that a non-prefix binding for <ESC> in
- any context prevents recognition of escape sequences as function
- keys in that context.
-
- * Applications should not bind mouse events based on button 1 with
- the shift key held down. These events include `S-mouse-1',
- `M-S-mouse-1', `C-S-mouse-1', and so on. They are reserved for
- users.
-
- * Modes should redefine `mouse-2' as a command to follow some sort of
- reference in the text of a buffer, if users usually would not want
- to alter the text in that buffer by hand. Modes such as Dired,
- Info, Compilation, and Occur redefine it in this way.
-
- * When a package provides a modification of ordinary Emacs behavior,
- it is good to include a command to enable and disable the feature,
- Provide a command named `WHATEVER-mode' which turns the feature on
- or off, and make it autoload (*note Autoload::). Design the
- package so that simply loading it has no visible effect--that
- should not enable the feature. Users will request the feature by
- invoking the command.
-
- * It is a bad idea to define aliases for the Emacs primitives. Use
- the standard names instead.
-
- * Redefining an Emacs primitive is an even worse idea. It may do
- the right thing for a particular program, but there is no telling
- what other programs might break as a result.
-
- * If a file does replace any of the functions or library programs of
- standard XEmacs, prominent comments at the beginning of the file
- should say which functions are replaced, and how the behavior of
- the replacements differs from that of the originals.
-
- * Please keep the names of your XEmacs Lisp source files to 13
- characters or less. This way, if the files are compiled, the
- compiled files' names will be 14 characters or less, which is
- short enough to fit on all kinds of Unix systems.
-
- * Don't use `next-line' or `previous-line' in programs; nearly
- always, `forward-line' is more convenient as well as more
- predictable and robust. *Note Text Lines::.
-
- * Don't call functions that set the mark, unless setting the mark is
- one of the intended features of your program. The mark is a
- user-level feature, so it is incorrect to change the mark except
- to supply a value for the user's benefit. *Note The Mark::.
-
- In particular, don't use these functions:
-
- * `beginning-of-buffer', `end-of-buffer'
-
- * `replace-string', `replace-regexp'
-
- If you just want to move point, or replace a certain string,
- without any of the other features intended for interactive users,
- you can replace these functions with one or two lines of simple
- Lisp code.
-
- * Use lists rather than vectors, except when there is a particular
- reason to use a vector. Lisp has more facilities for manipulating
- lists than for vectors, and working with lists is usually more
- convenient.
-
- Vectors are advantageous for tables that are substantial in size
- and are accessed in random order (not searched front to back),
- provided there is no need to insert or delete elements (only lists
- allow that).
-
- * The recommended way to print a message in the echo area is with
- the `message' function, not `princ'. *Note The Echo Area::.
-
- * When you encounter an error condition, call the function `error'
- (or `signal'). The function `error' does not return. *Note
- Signaling Errors::.
-
- Do not use `message', `throw', `sleep-for', or `beep' to report
- errors.
-
- * An error message should start with a capital letter but should not
- end with a period.
-
- * Try to avoid using recursive edits. Instead, do what the Rmail `e'
- command does: use a new local keymap that contains one command
- defined to switch back to the old local keymap. Or do what the
- `edit-options' command does: switch to another buffer and let the
- user switch back at will. *Note Recursive Editing::.
-
- * In some other systems there is a convention of choosing variable
- names that begin and end with `*'. We don't use that convention
- in Emacs Lisp, so please don't use it in your programs. (Emacs
- uses such names only for program-generated buffers.) The users
- will find Emacs more coherent if all libraries use the same
- conventions.
-
- * Indent each function with `C-M-q' (`indent-sexp') using the
- default indentation parameters.
-
- * Don't make a habit of putting close-parentheses on lines by
- themselves; Lisp programmers find this disconcerting. Once in a
- while, when there is a sequence of many consecutive
- close-parentheses, it may make sense to split them in one or two
- significant places.
-
- * Please put a copyright notice on the file if you give copies to
- anyone. Use the same lines that appear at the top of the Lisp
- files in XEmacs itself. If you have not signed papers to assign
- the copyright to the Foundation, then place your name in the
- copyright notice in place of the Foundation's name.
-
-\1f
-File: lispref.info, Node: Compilation Tips, Next: Documentation Tips, Prev: Style Tips, Up: Tips
-
-Tips for Making Compiled Code Fast
-==================================
-
- Here are ways of improving the execution speed of byte-compiled Lisp
-programs.
-
- * Use the `profile' library to profile your program. See the file
- `profile.el' for instructions.
-
- * Use iteration rather than recursion whenever possible. Function
- calls are slow in XEmacs Lisp even when a compiled function is
- calling another compiled function.
-
- * Using the primitive list-searching functions `memq', `member',
- `assq', or `assoc' is even faster than explicit iteration. It may
- be worth rearranging a data structure so that one of these
- primitive search functions can be used.
-
- * Certain built-in functions are handled specially in byte-compiled
- code, avoiding the need for an ordinary function call. It is a
- good idea to use these functions rather than alternatives. To see
- whether a function is handled specially by the compiler, examine
- its `byte-compile' property. If the property is non-`nil', then
- the function is handled specially.
-
- For example, the following input will show you that `aref' is
- compiled specially (*note Array Functions::) while `elt' is not
- (*note Sequence Functions::):
-
- (get 'aref 'byte-compile)
- => byte-compile-two-args
-
- (get 'elt 'byte-compile)
- => nil
-
- * If calling a small function accounts for a substantial part of
- your program's running time, make the function inline. This
- eliminates the function call overhead. Since making a function
- inline reduces the flexibility of changing the program, don't do
- it unless it gives a noticeable speedup in something slow enough
- that users care about the speed. *Note Inline Functions::.
-
-\1f
-File: lispref.info, Node: Documentation Tips, Next: Comment Tips, Prev: Compilation Tips, Up: Tips
-
-Tips for Documentation Strings
-==============================
-
- Here are some tips for the writing of documentation strings.
-
- * Every command, function, or variable intended for users to know
- about should have a documentation string.
-
- * An internal variable or subroutine of a Lisp program might as well
- have a documentation string. In earlier Emacs versions, you could
- save space by using a comment instead of a documentation string,
- but that is no longer the case.
-
- * The first line of the documentation string should consist of one
- or two complete sentences that stand on their own as a summary.
- `M-x apropos' displays just the first line, and if it doesn't
- stand on its own, the result looks bad. In particular, start the
- first line with a capital letter and end with a period.
-
- The documentation string can have additional lines that expand on
- the details of how to use the function or variable. The
- additional lines should be made up of complete sentences also, but
- they may be filled if that looks good.
-
- * For consistency, phrase the verb in the first sentence of a
- documentation string as an infinitive with "to" omitted. For
- instance, use "Return the cons of A and B." in preference to
- "Returns the cons of A and B." Usually it looks good to do
- likewise for the rest of the first paragraph. Subsequent
- paragraphs usually look better if they have proper subjects.
-
- * Write documentation strings in the active voice, not the passive,
- and in the present tense, not the future. For instance, use
- "Return a list containing A and B." instead of "A list containing
- A and B will be returned."
-
- * Avoid using the word "cause" (or its equivalents) unnecessarily.
- Instead of, "Cause Emacs to display text in boldface," write just
- "Display text in boldface."
-
- * Do not start or end a documentation string with whitespace.
-
- * Format the documentation string so that it fits in an Emacs window
- on an 80-column screen. It is a good idea for most lines to be no
- wider than 60 characters. The first line can be wider if
- necessary to fit the information that ought to be there.
-
- However, rather than simply filling the entire documentation
- string, you can make it much more readable by choosing line breaks
- with care. Use blank lines between topics if the documentation
- string is long.
-
- * *Do not* indent subsequent lines of a documentation string so that
- the text is lined up in the source code with the text of the first
- line. This looks nice in the source code, but looks bizarre when
- users view the documentation. Remember that the indentation
- before the starting double-quote is not part of the string!
-
- * A variable's documentation string should start with `*' if the
- variable is one that users would often want to set interactively.
- If the value is a long list, or a function, or if the variable
- would be set only in init files, then don't start the
- documentation string with `*'. *Note Defining Variables::.
-
- * The documentation string for a variable that is a yes-or-no flag
- should start with words such as "Non-nil means...", to make it
- clear that all non-`nil' values are equivalent and indicate
- explicitly what `nil' and non-`nil' mean.
-
- * When a function's documentation string mentions the value of an
- argument of the function, use the argument name in capital letters
- as if it were a name for that value. Thus, the documentation
- string of the function `/' refers to its second argument as
- `DIVISOR', because the actual argument name is `divisor'.
-
- Also use all caps for meta-syntactic variables, such as when you
- show the decomposition of a list or vector into subunits, some of
- which may vary.
-
- * When a documentation string refers to a Lisp symbol, write it as it
- would be printed (which usually means in lower case), with
- single-quotes around it. For example: `lambda'. There are two
- exceptions: write t and nil without single-quotes. (In this
- manual, we normally do use single-quotes for those symbols.)
-
- * Don't write key sequences directly in documentation strings.
- Instead, use the `\\[...]' construct to stand for them. For
- example, instead of writing `C-f', write `\\[forward-char]'. When
- Emacs displays the documentation string, it substitutes whatever
- key is currently bound to `forward-char'. (This is normally `C-f',
- but it may be some other character if the user has moved key
- bindings.) *Note Keys in Documentation::.
-
- * In documentation strings for a major mode, you will want to refer
- to the key bindings of that mode's local map, rather than global
- ones. Therefore, use the construct `\\<...>' once in the
- documentation string to specify which key map to use. Do this
- before the first use of `\\[...]'. The text inside the `\\<...>'
- should be the name of the variable containing the local keymap for
- the major mode.
-
- It is not practical to use `\\[...]' very many times, because
- display of the documentation string will become slow. So use this
- to describe the most important commands in your major mode, and
- then use `\\{...}' to display the rest of the mode's keymap.
-
-\1f
-File: lispref.info, Node: Comment Tips, Next: Library Headers, Prev: Documentation Tips, Up: Tips
-
-Tips on Writing Comments
-========================
-
- We recommend these conventions for where to put comments and how to
-indent them:
-
-`;'
- Comments that start with a single semicolon, `;', should all be
- aligned to the same column on the right of the source code. Such
- comments usually explain how the code on the same line does its
- job. In Lisp mode and related modes, the `M-;'
- (`indent-for-comment') command automatically inserts such a `;' in
- the right place, or aligns such a comment if it is already present.
-
- This and following examples are taken from the Emacs sources.
-
- (setq base-version-list ; there was a base
- (assoc (substring fn 0 start-vn) ; version to which
- file-version-assoc-list)) ; this looks like
- ; a subversion
-
-`;;'
- Comments that start with two semicolons, `;;', should be aligned to
- the same level of indentation as the code. Such comments usually
- describe the purpose of the following lines or the state of the
- program at that point. For example:
-
- (prog1 (setq auto-fill-function
- ...
- ...
- ;; update modeline
- (redraw-modeline)))
-
- Every function that has no documentation string (because it is use
- only internally within the package it belongs to), should have
- instead a two-semicolon comment right before the function,
- explaining what the function does and how to call it properly.
- Explain precisely what each argument means and how the function
- interprets its possible values.
-
-`;;;'
- Comments that start with three semicolons, `;;;', should start at
- the left margin. Such comments are used outside function
- definitions to make general statements explaining the design
- principles of the program. For example:
-
- ;;; This Lisp code is run in XEmacs
- ;;; when it is to operate as a server
- ;;; for other processes.
-
- Another use for triple-semicolon comments is for commenting out
- lines within a function. We use triple-semicolons for this
- precisely so that they remain at the left margin.
-
- (defun foo (a)
- ;;; This is no longer necessary.
- ;;; (force-mode-line-update)
- (message "Finished with %s" a))
-
-`;;;;'
- Comments that start with four semicolons, `;;;;', should be aligned
- to the left margin and are used for headings of major sections of a
- program. For example:
-
- ;;;; The kill ring
-
-The indentation commands of the Lisp modes in XEmacs, such as `M-;'
-(`indent-for-comment') and <TAB> (`lisp-indent-line') automatically
-indent comments according to these conventions, depending on the number
-of semicolons. *Note Manipulating Comments: (emacs)Comments.
-
-\1f
-File: lispref.info, Node: Library Headers, Prev: Comment Tips, Up: Tips
-
-Conventional Headers for XEmacs Libraries
-=========================================
-
- XEmacs has conventions for using special comments in Lisp libraries
-to divide them into sections and give information such as who wrote
-them. This section explains these conventions. First, an example:
-
- ;;; lisp-mnt.el --- minor mode for Emacs Lisp maintainers
-
- ;; Copyright (C) 1992 Free Software Foundation, Inc.
-
- ;; Author: Eric S. Raymond <esr@snark.thyrsus.com>
- ;; Maintainer: Eric S. Raymond <esr@snark.thyrsus.com>
- ;; Created: 14 Jul 1992
- ;; Version: 1.2
- ;; Keywords: docs
-
- ;; This file is part of XEmacs.
- COPYING PERMISSIONS...
-
- The very first line should have this format:
-
- ;;; FILENAME --- DESCRIPTION
-
-The description should be complete in one line.
-
- After the copyright notice come several "header comment" lines, each
-beginning with `;; HEADER-NAME:'. Here is a table of the conventional
-possibilities for HEADER-NAME:
-
-`Author'
- This line states the name and net address of at least the principal
- author of the library.
-
- If there are multiple authors, you can list them on continuation
- lines led by `;;' and a tab character, like this:
-
- ;; Author: Ashwin Ram <Ram-Ashwin@cs.yale.edu>
- ;; Dave Sill <de5@ornl.gov>
- ;; Dave Brennan <brennan@hal.com>
- ;; Eric Raymond <esr@snark.thyrsus.com>
-
-`Maintainer'
- This line should contain a single name/address as in the Author
- line, or an address only, or the string `FSF'. If there is no
- maintainer line, the person(s) in the Author field are presumed to
- be the maintainers. The example above is mildly bogus because the
- maintainer line is redundant.
-
- The idea behind the `Author' and `Maintainer' lines is to make
- possible a Lisp function to "send mail to the maintainer" without
- having to mine the name out by hand.
-
- Be sure to surround the network address with `<...>' if you
- include the person's full name as well as the network address.
-
-`Created'
- This optional line gives the original creation date of the file.
- For historical interest only.
-
-`Version'
- If you wish to record version numbers for the individual Lisp
- program, put them in this line.
-
-`Adapted-By'
- In this header line, place the name of the person who adapted the
- library for installation (to make it fit the style conventions, for
- example).
-
-`Keywords'
- This line lists keywords for the `finder-by-keyword' help command.
- This field is important; it's how people will find your package
- when they're looking for things by topic area. To separate the
- keywords, you can use spaces, commas, or both.
-
- Just about every Lisp library ought to have the `Author' and
-`Keywords' header comment lines. Use the others if they are
-appropriate. You can also put in header lines with other header
-names--they have no standard meanings, so they can't do any harm.
-
- We use additional stylized comments to subdivide the contents of the
-library file. Here is a table of them:
-
-`;;; Commentary:'
- This begins introductory comments that explain how the library
- works. It should come right after the copying permissions.
-
-`;;; Change log:'
- This begins change log information stored in the library file (if
- you store the change history there). For most of the Lisp files
- distributed with XEmacs, the change history is kept in the file
- `ChangeLog' and not in the source file at all; these files do not
- have a `;;; Change log:' line.
-
-`;;; Code:'
- This begins the actual code of the program.
-
-`;;; FILENAME ends here'
- This is the "footer line"; it appears at the very end of the file.
- Its purpose is to enable people to detect truncated versions of
- the file from the lack of a footer line.
-
-\1f
-File: lispref.info, Node: Building XEmacs and Object Allocation, Next: Standard Errors, Prev: Tips, Up: Top
-
-Building XEmacs; Allocation of Objects
-**************************************
-
- This chapter describes how the runnable XEmacs executable is dumped
-with the preloaded Lisp libraries in it and how storage is allocated.
-
- There is an entire separate document, the `XEmacs Internals Manual',
-devoted to the internals of XEmacs from the perspective of the C
-programmer. It contains much more detailed information about the build
-process, the allocation and garbage-collection process, and other
-aspects related to the internals of XEmacs.
-
-* Menu:
-
-* Building XEmacs:: How to preload Lisp libraries into XEmacs.
-* Pure Storage:: A kludge to make preloaded Lisp functions sharable.
-* Garbage Collection:: Reclaiming space for Lisp objects no longer used.
-
-\1f
-File: lispref.info, Node: Building XEmacs, Next: Pure Storage, Up: Building XEmacs and Object Allocation
-
-Building XEmacs
-===============
-
- This section explains the steps involved in building the XEmacs
-executable. You don't have to know this material to build and install
-XEmacs, since the makefiles do all these things automatically. This
-information is pertinent to XEmacs maintenance.
-
- The `XEmacs Internals Manual' contains more information about this.
-
- Compilation of the C source files in the `src' directory produces an
-executable file called `temacs', also called a "bare impure XEmacs".
-It contains the XEmacs Lisp interpreter and I/O routines, but not the
-editing commands.
-
- Before XEmacs is actually usable, a number of Lisp files need to be
-loaded. These define all the editing commands, plus most of the startup
-code and many very basic Lisp primitives. This is accomplished by
-loading the file `loadup.el', which in turn loads all of the other
-standardly-loaded Lisp files.
-
- It takes a substantial time to load the standard Lisp files.
-Luckily, you don't have to do this each time you run XEmacs; `temacs'
-can dump out an executable program called `xemacs' that has these files
-preloaded. `xemacs' starts more quickly because it does not need to
-load the files. This is the XEmacs executable that is normally
-installed.
-
- To create `xemacs', use the command `temacs -batch -l loadup dump'.
-The purpose of `-batch' here is to tell `temacs' to run in
-non-interactive, command-line mode. (`temacs' can _only_ run in this
-fashion. Part of the code required to initialize frames and faces is
-in Lisp, and must be loaded before XEmacs is able to create any frames.)
-The argument `dump' tells `loadup.el' to dump a new executable named
-`xemacs'.
-
- The dumping process is highly system-specific, and some operating
-systems don't support dumping. On those systems, you must start XEmacs
-with the `temacs -batch -l loadup run-temacs' command each time you use
-it. This takes a substantial time, but since you need to start Emacs
-once a day at most--or once a week if you never log out--the extra time
-is not too severe a problem. (In older versions of Emacs, you started
-Emacs from `temacs' using `temacs -l loadup'.)
-
- You are free to start XEmacs directly from `temacs' if you want,
-even if there is already a dumped `xemacs'. Normally you wouldn't want
-to do that; but the Makefiles do this when you rebuild XEmacs using
-`make all-elc', which builds XEmacs and simultaneously compiles any
-out-of-date Lisp files. (You need `xemacs' in order to compile Lisp
-files. However, you also need the compiled Lisp files in order to dump
-out `xemacs'. If both of these are missing or corrupted, you are out
-of luck unless you're able to bootstrap `xemacs' from `temacs'. Note
-that `make all-elc' actually loads the alternative loadup file
-`loadup-el.el', which works like `loadup.el' but disables the
-pure-copying process and forces XEmacs to ignore any compiled Lisp
-files even if they exist.)
-
- You can specify additional files to preload by writing a library
-named `site-load.el' that loads them. You may need to increase the
-value of `PURESIZE', in `src/puresize.h', to make room for the
-additional files. You should _not_ modify this file directly, however;
-instead, use the `--puresize' configuration option. (If you run out of
-pure space while dumping `xemacs', you will be told how much pure space
-you actually will need.) However, the advantage of preloading
-additional files decreases as machines get faster. On modern machines,
-it is often not advisable, especially if the Lisp code is on a file
-system local to the machine running XEmacs.
-
- You can specify other Lisp expressions to execute just before dumping
-by putting them in a library named `site-init.el'. However, if they
-might alter the behavior that users expect from an ordinary unmodified
-XEmacs, it is better to put them in `default.el', so that users can
-override them if they wish. *Note Start-up Summary::.
-
- Before `loadup.el' dumps the new executable, it finds the
-documentation strings for primitive and preloaded functions (and
-variables) in the file where they are stored, by calling
-`Snarf-documentation' (*note Accessing Documentation::). These strings
-were moved out of the `xemacs' executable to make it smaller. *Note
-Documentation Basics::.
-
- - Function: dump-emacs to-file from-file
- This function dumps the current state of XEmacs into an executable
- file TO-FILE. It takes symbols from FROM-FILE (this is normally
- the executable file `temacs').
-
- If you use this function in an XEmacs that was already dumped, you
- must set `command-line-processed' to `nil' first for good results.
- *Note Command Line Arguments::.
-
- - Function: run-emacs-from-temacs &rest args
- This is the function that implements the `run-temacs' command-line
- argument. It is called from `loadup.el' as appropriate. You
- should most emphatically _not_ call this yourself; it will
- reinitialize your XEmacs process and you'll be sorry.
-
- - Command: emacs-version
- This function returns a string describing the version of XEmacs
- that is running. It is useful to include this string in bug
- reports.
-
- (emacs-version)
- => "XEmacs 20.1 [Lucid] (i586-unknown-linux2.0.29)
- of Mon Apr 7 1997 on altair.xemacs.org"
-
- Called interactively, the function prints the same information in
- the echo area.
-
- - Variable: emacs-build-time
- The value of this variable is the time at which XEmacs was built
- at the local site.
-
- emacs-build-time "Mon Apr 7 20:28:52 1997"
- =>
-
- - Variable: emacs-version
- The value of this variable is the version of Emacs being run. It
- is a string, e.g. `"20.1 XEmacs Lucid"'.
-
- The following two variables did not exist before FSF GNU Emacs
-version 19.23 and XEmacs version 19.10, which reduces their usefulness
-at present, but we hope they will be convenient in the future.
-
- - Variable: emacs-major-version
- The major version number of Emacs, as an integer. For XEmacs
- version 20.1, the value is 20.
-
- - Variable: emacs-minor-version
- The minor version number of Emacs, as an integer. For XEmacs
- version 20.1, the value is 1.
-
-\1f
-File: lispref.info, Node: Pure Storage, Next: Garbage Collection, Prev: Building XEmacs, Up: Building XEmacs and Object Allocation
-
-Pure Storage
-============
-
- XEmacs Lisp uses two kinds of storage for user-created Lisp objects:
-"normal storage" and "pure storage". Normal storage is where all the
-new data created during an XEmacs session is kept; see the following
-section for information on normal storage. Pure storage is used for
-certain data in the preloaded standard Lisp files--data that should
-never change during actual use of XEmacs.
-
- Pure storage is allocated only while `temacs' is loading the
-standard preloaded Lisp libraries. In the file `xemacs', it is marked
-as read-only (on operating systems that permit this), so that the
-memory space can be shared by all the XEmacs jobs running on the machine
-at once. Pure storage is not expandable; a fixed amount is allocated
-when XEmacs is compiled, and if that is not sufficient for the preloaded
-libraries, `temacs' aborts with an error message. If that happens, you
-must increase the compilation parameter `PURESIZE' using the
-`--puresize' option to `configure'. This normally won't happen unless
-you try to preload additional libraries or add features to the standard
-ones.
-
- - Function: purecopy object
- This function makes a copy of OBJECT in pure storage and returns
- it. It copies strings by simply making a new string with the same
- characters in pure storage. It recursively copies the contents of
- vectors and cons cells. It does not make copies of other objects
- such as symbols, but just returns them unchanged. It signals an
- error if asked to copy markers.
-
- This function is a no-op except while XEmacs is being built and
- dumped; it is usually called only in the file
- `xemacs/lisp/prim/loaddefs.el', but a few packages call it just in
- case you decide to preload them.
-
- - Variable: pure-bytes-used
- The value of this variable is the number of bytes of pure storage
- allocated so far. Typically, in a dumped XEmacs, this number is
- very close to the total amount of pure storage available--if it
- were not, we would preallocate less.
-
- - Variable: purify-flag
- This variable determines whether `defun' should make a copy of the
- function definition in pure storage. If it is non-`nil', then the
- function definition is copied into pure storage.
-
- This flag is `t' while loading all of the basic functions for
- building XEmacs initially (allowing those functions to be sharable
- and non-collectible). Dumping XEmacs as an executable always
- writes `nil' in this variable, regardless of the value it actually
- has before and after dumping.
-
- You should not change this flag in a running XEmacs.
-
projects / chise / xemacs-chise.git / blobdiff