* Registers:: How registers are implemented. Accessing the text or
position stored in a register.
* Base 64:: Conversion to or from base 64 encoding.
-* MD5 Checksum:: Compute the MD5 ``message digest''/``checksum''.
-* Atomic Changes:: Installing several buffer changes ``atomically''.
+* MD5 Checksum:: Compute the MD5 "message digest"/"checksum".
+* Atomic Changes:: Installing several buffer changes "atomically".
* Change Hooks:: Supplying functions to be run when text is changed.
@end menu
buffer. This is similar to @code{(char-after (point))}. However, if
point is at the end of the buffer, then @code{following-char} returns 0.
-Remember that point is always between characters, and the terminal
-cursor normally appears over the character following point. Therefore,
-the character returned by @code{following-char} is the character the
+Remember that point is always between characters, and the cursor
+normally appears over the character following point. Therefore, the
+character returned by @code{following-char} is the character the
cursor is over.
In this example, point is between the @samp{a} and the @samp{c}.
@end example
@end defun
-@tindex current-word
@defun current-word &optional strict really-word
This function returns the symbol (or word) at or near point, as a string.
The return value includes no text properties.
is the numeric prefix argument.
@end deffn
-@deffn Command split-line
-This command splits the current line, moving the portion of the line
-after point down vertically so that it is on the next line directly
-below where it was before. Whitespace is inserted as needed at the
-beginning of the lower line, using the @code{indent-to} function.
-@code{split-line} returns the position of point.
-
-Programs hardly ever use this function.
-@end deffn
-
@defvar overwrite-mode
This variable controls whether overwrite mode is in effect. The value
should be @code{overwrite-mode-textual}, @code{overwrite-mode-binary},
asking for any confirmation. It returns @code{nil}.
Normally, deleting a large amount of text from a buffer inhibits further
-auto-saving of that buffer ``because it has shrunk''. However,
+auto-saving of that buffer ``because it has shrunk.'' However,
@code{erase-buffer} does not do this, the idea being that the future
text is not really related to the former text, and its size should not
be compared with that of the former text.
@end deffn
@defun delete-and-extract-region start end
-@tindex delete-and-extract-region
This function deletes the text between positions @var{start} and
@var{end} in the current buffer, and returns a string containing the
text just deleted.
Some people think this use of the word ``kill'' is unfortunate, since
it refers to operations that specifically @emph{do not} destroy the
-entities ``killed''. This is in sharp contrast to ordinary life, in
+entities ``killed.'' This is in sharp contrast to ordinary life, in
which death is permanent and ``killed'' entities do not come back to
life. Therefore, other metaphors have been proposed. For example, the
term ``cut ring'' makes sense to people who, in pre-computer days, used
@comment node-name, next, previous, up
@subsection Functions for Yanking
- @dfn{Yanking} means reinserting an entry of previously killed text
-from the kill ring. The text properties are copied too.
+ This section describes higher-level commands for yanking, which are
+intended primarily for the user but useful also in Lisp programs.
+Both @code{yank} and @code{yank-pop} honor the
+@code{yank-excluded-properties} variable and @code{yank-handler} text
+property (@pxref{Yanking}).
@deffn Command yank &optional arg
@cindex inserting killed text
@code{nil} or a function of no arguments.
If the value is a function, @code{current-kill} calls it to get the
-``most recent kill''. If the function returns a non-@code{nil} value,
-then that value is used as the ``most recent kill''. If it returns
+``most recent kill.'' If the function returns a non-@code{nil} value,
+then that value is used as the ``most recent kill.'' If it returns
@code{nil}, then the front of the kill ring is used.
The normal use of this hook is to get the window system's primary
to the buffer's text so that they can be undone. (The buffers that
don't have one are usually special-purpose buffers for which Emacs
assumes that undoing is not useful. In particular, any buffer whose
-name begins with a space has its undo recording off by default,
+name begins with a space has its undo recording off by default;
see @ref{Buffer Names}.) All the primitives that modify the
text in the buffer automatically add elements to the front of the undo
list, which is in the variable @code{buffer-undo-list}.
@defun primitive-undo count list
This is the basic function for undoing elements of an undo list.
It undoes the first @var{count} elements of @var{list}, returning
-the rest of @var{list}. You could write this function in Lisp,
-but it is convenient to have it in C.
+the rest of @var{list}.
@code{primitive-undo} adds elements to the buffer's undo list when it
changes the buffer. Undo commands avoid confusion by saving the undo
of an undo list measures the cons cells that make up the list, plus the
strings of deleted text.) Three variables control the range of acceptable
sizes: @code{undo-limit}, @code{undo-strong-limit} and
-@code{undo-outer-limit}.
+@code{undo-outer-limit}. In these variables, size is counted as the
+number of bytes occupied, which includes both saved text and other
+data.
@defopt undo-limit
This is the soft limit for the acceptable size of an undo list. The
This is a last ditch limit to prevent memory overflow.
@end defopt
+@defopt undo-ask-before-discard
+If this variable is non-@code{nil}, when the undo info exceeds
+@code{undo-outer-limit}, Emacs asks in the echo area whether to
+discard the info. The default value is @code{nil}, which means to
+discard it automatically.
+
+This option is mainly intended for debugging. Garbage collection is
+inhibited while the question is asked, which means that Emacs might
+leak memory if the user waits too long before answering the question.
+@end defopt
+
@node Filling
@comment node-name, next, previous, up
@section Filling
between paragraphs are removed. This function justifies as well as
filling when @var{justify} is non-@code{nil}.
-In an interactive call, any prefix argument requests justification.
-
If @var{nosqueeze} is non-@code{nil}, that means to leave whitespace
other than line breaks untouched. If @var{squeeze-after} is
non-@code{nil}, it specifies a position in the region, and means don't
@defun current-justification
This function returns the proper justification style to use for filling
the text around point.
+
+This returns the value of the @code{justification} text property at
+point, or the variable @var{default-justification} if there is no such
+text property. However, it returns @code{nil} rather than @code{none}
+to mean ``don't justify''.
@end defun
@defopt sentence-end-double-space
@section Margins for Filling
@defopt fill-prefix
-This buffer-local variable specifies a string of text that appears at
-the beginning
-of normal text lines and should be disregarded when filling them. Any
-line that fails to start with the fill prefix is considered the start of
-a paragraph; so is any line that starts with the fill prefix followed by
-additional whitespace. Lines that start with the fill prefix but no
-additional whitespace are ordinary text lines that can be filled
-together. The resulting filled lines also start with the fill prefix.
+This buffer-local variable, if non-@code{nil}, specifies a string of
+text that appears at the beginning of normal text lines and should be
+disregarded when filling them. Any line that fails to start with the
+fill prefix is considered the start of a paragraph; so is any line
+that starts with the fill prefix followed by additional whitespace.
+Lines that start with the fill prefix but no additional whitespace are
+ordinary text lines that can be filled together. The resulting filled
+lines also start with the fill prefix.
The fill prefix follows the left margin whitespace, if any.
@end defopt
@defvar fill-nobreak-predicate
This variable gives major modes a way to specify not to break a line
-at certain places. Its value should be a list of functions, but a
-single function is also supported for compatibility. Whenever filling
-considers breaking the line at a certain place in the buffer, it calls
-each of these functions with no arguments and with point located at
-that place. If any of the functions returns non-@code{nil}, then the
-line won't be broken there.
+at certain places. Its value should be a list of functions. Whenever
+filling considers breaking the line at a certain place in the buffer,
+it calls each of these functions with no arguments and with point
+located at that place. If any of the functions returns
+non-@code{nil}, then the line won't be broken there.
@end defvar
@node Adaptive Fill
starting after the left margin whitespace (if any) on a line; the
characters it matches are that line's candidate for the fill prefix.
-@w{@code{"[ \t]*\\([-|#;>*]+[ \t]*\\|(?[0-9]+[.)][ \t]*\\)*"}} is the
+@w{@code{"[ \t]*\\([-!|#%;>*·•‣⁃◦]+[ \t]*\\|(?[0-9]+[.)][ \t]*\\)*"}} is the
default value. This matches a number enclosed in parentheses or
followed by a period, or certain punctuation characters, or any
sequence of these intermingled with whitespace. In particular, it
(save-restriction
(narrow-to-region beg end)
(goto-char (point-min))
- (sort-subr reverse 'forward-line 'end-of-line))))
+ (let ((inhibit-field-text-motion t))
+ (sort-subr reverse 'forward-line 'end-of-line)))))
@end group
@end example
containing position @var{beg}, and the entire line containing position
@var{end}, are included in the region sorted.
-Note that @code{sort-columns} uses the @code{sort} utility program,
-and so cannot work properly on text containing tab characters. Use
-@kbd{M-x untabify} to convert tabs to spaces before sorting.
+Note that @code{sort-columns} rejects text that contains tabs, because
+tabs could be split across the specified columns. Use @kbd{M-x
+untabify} to convert tabs to spaces before sorting.
+
+When possible, this command actually works by calling the @code{sort}
+utility program.
@end deffn
@node Columns
affect the display of tab characters in the buffer (@pxref{Usual
Display}). Note that the @key{TAB} character as input uses this tab
stop feature only in a few major modes, such as Text mode.
+@xref{Tab Stops,,, emacs, The GNU Emacs Manual}.
@deffn Command tab-to-tab-stop
This command inserts spaces or tabs before point, up to the next tab
is with @code{propertize}:
@defun propertize string &rest properties
-@tindex propertize
This function returns a copy of @var{string} which has the text
properties @var{properties}. These properties apply to all the
characters in the string that is returned. Here is an example that
@end defun
@defun next-single-char-property-change pos prop &optional object limit
-@tindex next-single-char-property-change
This is like @code{next-single-property-change} except that it
considers overlay properties as well as text properties, and if no
change is found before the end of the @var{object}, it returns the
@end defun
@defun previous-single-char-property-change pos prop &optional object limit
-@tindex previous-single-char-property-change
This is like @code{next-single-char-property-change}, but scans back
from @var{pos} instead of forward, and returns the minimum valid
position in @var{object} if no change is found.
@item fontified
@kindex fontified @r{(text property)}
-This property says whether the text has had faces assigned to it by
-font locking. The display engine tests it to decide whether a buffer
+This property says whether the character has a face assigned to it by font
+locking. The display engine tests it to decide whether a buffer
portion needs refontifying before display. @xref{Auto Faces}. It
-takes one of these three values---other values are invalid:
+takes one of three values:
@table @asis
@item @code{nil}
-Font locking is disabled, or the @code{face} properties on the text,
-if any, are invalid.
+Font locking is disabled, or the character's @code{face} property, if
+any, is invalid.
-@item The symbol @code{defer}
-This value states that the text's @code{face} properties are invalid
-and marks it for deferred fontification. It is used only when ``just
-in time'' font locking is enabled.
+@item @code{defer}
+This value is only used when ``just in time'' font locking is enabled
+and it means that the character's @code{face} property is invalid and
+needs deferred fontification.
@item @code{t}
-The @code{face} properties, or lack of them, on the text are currently
-valid.
+The character's @code{face} property, or absence of one, is valid.
@end table
@item display
@itemize @bullet{}
@item
-If @var{object} is a buffer, @var{pos} is the position in the buffer
-where the @code{help-echo} text property was found.
+If @var{object} is a buffer, @var{pos} is the position in the buffer.
@item
If @var{object} is an overlay, that overlay has a @code{help-echo}
-property, and @var{pos} is the position in the overlay's buffer under
-the mouse.
+property, and @var{pos} is the position in the overlay's buffer.
@item
If @var{object} is a string (an overlay string or a string displayed
with the @code{display} property), @var{pos} is the position in that
-string under the mouse.
+string.
@end itemize
If the value of the @code{help-echo} property is neither a function nor
@cindex keymap of character
@kindex keymap @r{(text property)}
The @code{keymap} property specifies an additional keymap for
-commands. The property's value for the character before point applies
-if it is non-@code{nil} and rear-sticky, and the property's value for
-the character after point applies if it is non-@code{nil} and
+commands. When this keymap applies, it is used for key lookup before
+the minor mode keymaps and before the buffer's local map.
+@xref{Active Keymaps}. If the property value is a symbol, the
+symbol's function definition is used as the keymap.
+
+The property's value for the character before point applies if it is
+non-@code{nil} and rear-sticky, and the property's value for the
+character after point applies if it is non-@code{nil} and
front-sticky. (For mouse clicks, the position of the click is used
-instead of the position of point.) If the property value is a symbol,
-the symbol's function definition is used as the keymap.
-
-When this keymap applies, it is used for key lookup before the minor
-mode keymaps and before the buffer's local map. @xref{Active
-Keymaps}.
+instead of the position of point.)
@item local-map
@kindex local-map @r{(text property)}
This property works like @code{keymap} except that it specifies a
keymap to use @emph{instead of} the buffer's local map. For most
-purposes (perhaps all purposes), the @code{keymap} is superior.
+purposes (perhaps all purposes), it is better to use the @code{keymap}
+property.
@item syntax-table
The @code{syntax-table} property overrides what the syntax table says
@end defvar
@defvar show-help-function
-@tindex show-help-function
@anchor{Help display} If this variable is non-@code{nil}, it specifies a
function called to display help strings. These may be @code{help-echo}
properties, menu help strings (@pxref{Simple Menu Items},
list.
@defvar text-property-default-nonsticky
-@tindex text-property-default-nonsticky
This variable holds an alist which defines the default rear-stickiness
of various text properties. Each element has the form
@code{(@var{property} . @var{nonstickiness})}, and it defines the
@subsection Defining Clickable Text
@cindex clickable text
- There are two ways to set up @dfn{clickable text} in a buffer.
-There are typically two parts of this: to make the text highlight
-when the mouse is over it, and to make a mouse button do something
-when you click it on that part of the text.
-
- Highlighting is done with the @code{mouse-face} text property.
+ @dfn{Clickable text} is text that can be clicked, with either the
+the mouse or via keyboard commands, to produce some result. Many
+major modes use clickable text to implement features such as
+hyper-links. The @code{button} package provides an easy way to insert
+and manipulate clickable text. @xref{Buttons}.
+
+ In this section, we will explain how to manually set up clickable
+text in a buffer using text properties. This involves two things: (1)
+indicating clickability when the mouse moves over the text, and (2)
+making @kbd{RET} or a mouse click on that text do something.
+
+ Indicating clickability usually involves highlighting the text, and
+often involves displaying helpful information about the action, such
+as which mouse button to press, or a short summary of the action.
+This can be done with the @code{mouse-face} and @code{help-echo}
+text properties. @xref{Special Properties}.
Here is an example of how Dired does it:
@smallexample
(condition-case nil
(if (dired-move-to-filename)
- (put-text-property (point)
- (save-excursion
- (dired-move-to-end-of-filename)
- (point))
- 'mouse-face 'highlight))
+ (add-text-properties
+ (point)
+ (save-excursion
+ (dired-move-to-end-of-filename)
+ (point))
+ '(mouse-face highlight
+ help-echo "mouse-2: visit this file in other window")))
(error nil))
@end smallexample
@noindent
-The first two arguments to @code{put-text-property} specify the
+The first two arguments to @code{add-text-properties} specify the
beginning and end of the text.
The usual way to make the mouse do something when you click it
@smallexample
(defun dired-mouse-find-file-other-window (event)
- "In dired, visit the file or directory name you click on."
+ "In Dired, visit the file or directory name you click on."
(interactive "e")
- (let (file)
+ (let (window pos file)
(save-excursion
- (set-buffer (window-buffer (posn-window (event-end event))))
- (save-excursion
- (goto-char (posn-point (event-end event)))
- (setq file (dired-get-filename))))
- (select-window (posn-window (event-end event)))
- (find-file-other-window (file-name-sans-versions file t))))
+ (setq window (posn-window (event-end event))
+ pos (posn-point (event-end event)))
+ (if (not (windowp window))
+ (error "No file chosen"))
+ (set-buffer (window-buffer window))
+ (goto-char pos)
+ (setq file (dired-get-file-for-visit)))
+ (if (file-directory-p file)
+ (or (and (cdr dired-subdir-alist)
+ (dired-goto-subdir file))
+ (progn
+ (select-window window)
+ (dired-other-window file)))
+ (select-window window)
+ (find-file-other-window (file-name-sans-versions file t)))))
@end smallexample
@noindent
-The reason for the outer @code{save-excursion} construct is to avoid
-changing the current buffer; the reason for the inner one is to avoid
-permanently altering point in the buffer you click on. In this case,
-Dired uses the function @code{dired-get-filename} to determine which
-file to visit, based on the position found in the event.
+The reason for the @code{save-excursion} construct is to avoid
+changing the current buffer. In this case,
+Dired uses the functions @code{posn-window} and @code{posn-point}
+to determine which buffer the click happened in and where, and
+in that buffer, @code{dired-get-file-for-visit} to determine which
+file to visit.
Instead of defining a mouse command for the major mode, you can define
a key binding for the clickable text itself, using the @code{keymap}
@end smallexample
@defun mouse-on-link-p pos
-@tindex mouse-on-link-p
This function returns non-@code{nil} if position @var{pos} in the
-current buffer is on a link.
+current buffer is on a link. @var{pos} can also be a mouse event
+location, as returned by @code{event-start} (@pxref{Accessing Events}).
@end defun
@node Fields
to an empty field whose beginning and end are both at @var{pos}.
In all of these functions, if @var{pos} is omitted or @code{nil}, the
-value of point is used by default.
+value of point is used by default. If narrowing is in effect, then
+@var{pos} should fall within the accessible portion. @xref{Narrowing}.
@defun field-beginning &optional pos escape-from-edge limit
-@tindex field-beginning
This function returns the beginning of the field specified by @var{pos}.
If @var{pos} is at the beginning of its field, and
@end defun
@defun field-end &optional pos escape-from-edge limit
-@tindex field-end
This function returns the end of the field specified by @var{pos}.
If @var{pos} is at the end of its field, and @var{escape-from-edge} is
@end defun
@defun field-string &optional pos
-@tindex field-string
This function returns the contents of the field specified by @var{pos},
as a string.
@end defun
@defun field-string-no-properties &optional pos
-@tindex field-string-no-properties
This function returns the contents of the field specified by @var{pos},
as a string, discarding text properties.
@end defun
@defun delete-field &optional pos
-@tindex delete-field
This function deletes the text of the field specified by @var{pos}.
@end defun
@defun constrain-to-field new-pos old-pos &optional escape-from-edge only-in-line inhibit-capture-property
-@tindex constrain-to-field
This function ``constrains'' @var{new-pos} to the field that
@var{old-pos} belongs to---in other words, it returns the position
closest to @var{new-pos} that is in the same field as @var{old-pos}.
converting to and from this code.
@defun base64-encode-region beg end &optional no-line-break
-@tindex base64-encode-region
This function converts the region from @var{beg} to @var{end} into base
64 code. It returns the length of the encoded text. An error is
signaled if a character in the region is multibyte, i.e.@: in a
@end defun
@defun base64-encode-string string &optional no-line-break
-@tindex base64-encode-string
This function converts the string @var{string} into base 64 code. It
returns a string containing the encoded text. As for
@code{base64-encode-region}, an error is signaled if a character in the
@end defun
@defun base64-decode-region beg end
-@tindex base64-decode-region
This function converts the region from @var{beg} to @var{end} from base
64 code into the corresponding decoded text. It returns the length of
the decoded text.
@end defun
@defun base64-decode-string string
-@tindex base64-decode-string
This function converts the string @var{string} from base 64 code into
the corresponding decoded text. It returns a unibyte string containing the
decoded text.
@end defvar
@defvar inhibit-modification-hooks
-@tindex inhibit-modification-hooks
If this variable is non-@code{nil}, all of the change hooks are
disabled; none of them run. This affects all the hook variables
described above in this section, as well as the hooks attached to