-This is ../info/lispref.info, produced by makeinfo version 4.0 from
+This is ../info/lispref.info, produced by makeinfo version 4.0b from
lispref/lispref.texi.
INFO-DIR-SECTION XEmacs Editor
Foundation instead of in the original English.
\1f
-File: lispref.info, Node: Specifier Instancing, Next: Specifier Types, Prev: Specifiers In-Depth, Up: Specifiers
-
-How a Specifier Is Instanced
-============================
-
- Instancing of a specifier in a particular window domain proceeds as
-follows:
-
- * First, XEmacs searches for a specification whose locale is the
- same as the window. If that fails, the search is repeated,
- looking for a locale that is the same as the window's buffer. If
- that fails, the search is repeated using the window's frame, then
- using the device that frame is on. Finally, the specification
- whose locale is the symbol `global' (if there is such a
- specification) is considered.
-
- * The inst-pairs contained in the specification that was found are
- considered in their order in the inst-list, looking for one whose
- tag set matches the device that is derived from the window domain.
- (The tag set is an unordered list of zero or more tag symbols.
- For all tags that have predicates associated with them, the
- predicate must match the device.)
-
- * If a matching tag set is found, the corresponding instantiator is
- passed to the specifier's instantiation method, which is specific
- to the type of the specifier. If it succeeds, the resulting
- instance object is returned as the result of the instancing and
- the instancing is done. Otherwise, the operation continues,
- looking for another matching inst-pair in the current
- specification.
-
- * When there are no more inst-pairs to be considered in the current
- specification, the search starts over, looking for another
- specification as in the first step above.
-
- * If all specifications are exhausted and no instance object can be
- derived, the instancing fails. (Actually, this is not completely
- true. Some specifier objects for built-in properties have a
- "fallback" value, which is either an inst-list or another
- specifier object, that is consulted if the instancing is about to
- fail. If it is an inst-list, the searching proceeds using the
- inst-pairs in that list. If it is a specifier, the entire
- instancing starts over using that specifier instead of the given
- one. Fallback values are set by the C code and cannot be
- modified, except perhaps indirectly, using any Lisp functions.
- The purpose of them is to supply some values to make sure that
- instancing of built-in properties can't fail and to implement some
- basic specifier inheritance, such as the fact that faces inherit
- their properties from the `default' face.)
-
- It is also possible to instance a specifier over a frame domain or
-device domain instead of over a window domain. The C code, for example,
-instances the `top-toolbar-height' variable over a frame domain in
-order to determine the height of a frame's top toolbar. Instancing over
-a frame or device is similar to instancing over a window except that
-specifications for locales that cannot be derived from the domain are
-ignored. Specifically, instancing over a frame looks first for frame
-locales, then device locales, then the `global' locale. Instancing
-over a device domain looks only for device locales and the `global'
-locale.
+File: lispref.info, Node: Abbrev Expansion, Next: Standard Abbrev Tables, Prev: Abbrev Files, Up: Abbrevs
+
+Looking Up and Expanding Abbreviations
+======================================
+
+ Abbrevs are usually expanded by commands for interactive use,
+including `self-insert-command'. This section describes the
+subroutines used in writing such functions, as well as the variables
+they use for communication.
+
+ - Function: abbrev-symbol abbrev &optional table
+ This function returns the symbol representing the abbrev named
+ ABBREV. The value returned is `nil' if that abbrev is not
+ defined. The optional second argument TABLE is the abbrev table
+ to look it up in. If TABLE is `nil', this function tries first
+ the current buffer's local abbrev table, and second the global
+ abbrev table.
+
+ - Function: abbrev-expansion abbrev &optional table
+ This function returns the string that ABBREV would expand into (as
+ defined by the abbrev tables used for the current buffer). The
+ optional argument TABLE specifies the abbrev table to use, as in
+ `abbrev-symbol'.
+
+ - Command: expand-abbrev
+ This command expands the abbrev before point, if any. If point
+ does not follow an abbrev, this command does nothing. The command
+ returns `t' if it did expansion, `nil' otherwise.
+
+ - Command: abbrev-prefix-mark &optional arg
+ Mark current point as the beginning of an abbrev. The next call to
+ `expand-abbrev' will use the text from here to point (where it is
+ then) as the abbrev to expand, rather than using the previous word
+ as usual.
+
+ - User Option: abbrev-all-caps
+ When this is set non-`nil', an abbrev entered entirely in upper
+ case is expanded using all upper case. Otherwise, an abbrev
+ entered entirely in upper case is expanded by capitalizing each
+ word of the expansion.
+
+ - Variable: abbrev-start-location
+ This is the buffer position for `expand-abbrev' to use as the start
+ of the next abbrev to be expanded. (`nil' means use the word
+ before point instead.) `abbrev-start-location' is set to `nil'
+ each time `expand-abbrev' is called. This variable is also set by
+ `abbrev-prefix-mark'.
+
+ - Variable: abbrev-start-location-buffer
+ The value of this variable is the buffer for which
+ `abbrev-start-location' has been set. Trying to expand an abbrev
+ in any other buffer clears `abbrev-start-location'. This variable
+ is set by `abbrev-prefix-mark'.
+
+ - Variable: last-abbrev
+ This is the `abbrev-symbol' of the last abbrev expanded. This
+ information is left by `expand-abbrev' for the sake of the
+ `unexpand-abbrev' command.
+
+ - Variable: last-abbrev-location
+ This is the location of the last abbrev expanded. This contains
+ information left by `expand-abbrev' for the sake of the
+ `unexpand-abbrev' command.
+
+ - Variable: last-abbrev-text
+ This is the exact expansion text of the last abbrev expanded,
+ after case conversion (if any). Its value is `nil' if the abbrev
+ has already been unexpanded. This contains information left by
+ `expand-abbrev' for the sake of the `unexpand-abbrev' command.
+
+ - Variable: pre-abbrev-expand-hook
+ This is a normal hook whose functions are executed, in sequence,
+ just before any expansion of an abbrev. *Note Hooks::. Since it
+ is a normal hook, the hook functions receive no arguments.
+ However, they can find the abbrev to be expanded by looking in the
+ buffer before point.
+
+ The following sample code shows a simple use of
+`pre-abbrev-expand-hook'. If the user terminates an abbrev with a
+punctuation character, the hook function asks for confirmation. Thus,
+this hook allows the user to decide whether to expand the abbrev, and
+aborts expansion if it is not confirmed.
+
+ (add-hook 'pre-abbrev-expand-hook 'query-if-not-space)
+
+ ;; This is the function invoked by `pre-abbrev-expand-hook'.
+
+ ;; If the user terminated the abbrev with a space, the function does
+ ;; nothing (that is, it returns so that the abbrev can expand). If the
+ ;; user entered some other character, this function asks whether
+ ;; expansion should continue.
+
+ ;; If the user answers the prompt with `y', the function returns
+ ;; `nil' (because of the `not' function), but that is
+ ;; acceptable; the return value has no effect on expansion.
+
+ (defun query-if-not-space ()
+ (if (/= ?\ (preceding-char))
+ (if (not (y-or-n-p "Do you want to expand this abbrev? "))
+ (error "Not expanding this abbrev"))))
\1f
-File: lispref.info, Node: Specifier Types, Next: Adding Specifications, Prev: Specifier Instancing, Up: Specifiers
+File: lispref.info, Node: Standard Abbrev Tables, Prev: Abbrev Expansion, Up: Abbrevs
-Specifier Types
-===============
-
- There are various different types of specifiers. The type of a
-specifier controls what sorts of instantiators are valid, how an
-instantiator is instantiated, etc. Here is a list of built-in specifier
-types:
-
-`boolean'
- The valid instantiators are the symbols `t' and `nil'. Instance
- objects are the same as instantiators so no special instantiation
- function is needed.
-
-`integer'
- The valid instantiators are integers. Instance objects are the
- same as instantiators so no special instantiation function is
- needed. `modeline-shadow-thickness' is an example of an integer
- specifier (negative thicknesses indicate that the shadow is drawn
- recessed instead of raised).
-
-`natnum'
- The valid instantiators are natnums (non-negative integers).
- Instance objects are the same as instantiators so no special
- instantiation function is needed. Natnum specifiers are used for
- dimension variables such as `top-toolbar-height'.
-
-`generic'
- All Lisp objects are valid instantiators. Instance objects are
- the same as instantiators so no special instantiation function is
- needed.
-
-`font'
- The valid instantiators are strings describing fonts or vectors
- indicating inheritance from the font of some face. Instance
- objects are font-instance objects, which are specific to a
- particular device. The instantiation method for font specifiers
- can fail, unlike for integer, natnum, boolean, and generic
- specifiers.
-
-`color'
- The valid instantiators are strings describing colors or vectors
- indicating inheritance from the foreground or background of some
- face. Instance objects are color-instance objects, which are
- specific to a particular device. The instantiation method for
- color specifiers can fail, as for font specifiers.
-
-`image'
- Images are perhaps the most complicated type of built-in
- specifier. The valid instantiators are strings (a filename,
- inline data for a pixmap, or text to be displayed in a text glyph)
- or vectors describing inline data of various sorts or indicating
- inheritance from the background-pixmap property of some face.
- Instance objects are either strings (for text images),
- image-instance objects (for pixmap images), or subwindow objects
- (for subwindow images). The instantiation method for image
- specifiers can fail, as for font and color specifiers.
-
-`face-boolean'
- The valid instantiators are the symbols `t' and `nil' and vectors
- indicating inheritance from a boolean property of some face.
- Specifiers of this sort are used for all of the built-in boolean
- properties of faces. Instance objects are either the symbol `t'
- or the symbol `nil'.
-
-`toolbar'
- The valid instantiators are toolbar descriptors, which are lists
- of toolbar-button descriptors (each of which is a vector of two or
- four elements). *Note Toolbar::, for more information.
-
- Color and font instance objects can also be used in turn as
-instantiators for a new color or font instance object. Since these
-instance objects are device-specific, the instantiator can be used
-directly as the new instance object, but only if they are of the same
-device. If the devices differ, the base color or font of the
-instantiating object is effectively used instead as the instantiator.
-
- *Note Faces and Window-System Objects::, for more information on
-fonts, colors, and face-boolean specifiers. *Note Glyphs::, for more
-information about image specifiers. *Note Toolbar::, for more
-information on toolbar specifiers.
-
- - Function: specifier-type specifier
- This function returns the type of SPECIFIER. The returned value
- will be a symbol: one of `integer', `boolean', etc., as listed in
- the above table.
-
- Functions are also provided to query whether an object is a
-particular kind of specifier:
-
- - Function: boolean-specifier-p object
- This function returns non-`nil' if OBJECT is a boolean specifier.
-
- - Function: integer-specifier-p object
- This function returns non-`nil' if OBJECT is an integer specifier.
-
- - Function: natnum-specifier-p object
- This function returns non-`nil' if OBJECT is a natnum specifier.
-
- - Function: generic-specifier-p object
- This function returns non-`nil' if OBJECT is a generic specifier.
-
- - Function: face-boolean-specifier-p object
- This function returns non-`nil' if OBJECT is a face-boolean
- specifier.
-
- - Function: toolbar-specifier-p object
- This function returns non-`nil' if OBJECT is a toolbar specifier.
-
- - Function: font-specifier-p object
- This function returns non-`nil' if OBJECT is a font specifier.
-
- - Function: color-specifier-p object
- This function returns non-`nil' if OBJECT is a color specifier.
-
- - Function: image-specifier-p object
- This function returns non-`nil' if OBJECT is an image specifier.
-
-\1f
-File: lispref.info, Node: Adding Specifications, Next: Retrieving Specifications, Prev: Specifier Types, Up: Specifiers
+Standard Abbrev Tables
+======================
-Adding specifications to a Specifier
-====================================
+ Here we list the variables that hold the abbrev tables for the
+preloaded major modes of XEmacs.
- - Function: add-spec-to-specifier specifier instantiator &optional
- locale tag-set how-to-add
- This function adds a specification to SPECIFIER. The
- specification maps from LOCALE (which should be a window, buffer,
- frame, device, or the symbol `global', and defaults to `global')
- to INSTANTIATOR, whose allowed values depend on the type of the
- specifier. Optional argument TAG-SET limits the instantiator to
- apply only to the specified tag set, which should be a list of
- tags all of which must match the device being instantiated over
- (tags are a device type, a device class, or tags defined with
- `define-specifier-tag'). Specifying a single symbol for TAG-SET
- is equivalent to specifying a one-element list containing that
- symbol. Optional argument HOW-TO-ADD specifies what to do if
- there are already specifications in the specifier. It should be
- one of
+ - Variable: global-abbrev-table
+ This is the abbrev table for mode-independent abbrevs. The abbrevs
+ defined in it apply to all buffers. Each buffer may also have a
+ local abbrev table, whose abbrev definitions take precedence over
+ those in the global table.
- `prepend'
- Put at the beginning of the current list of instantiators for
- LOCALE.
+ - Variable: local-abbrev-table
+ The value of this buffer-local variable is the (mode-specific)
+ abbreviation table of the current buffer.
- `append'
- Add to the end of the current list of instantiators for
- LOCALE.
-
- `remove-tag-set-prepend'
- This is the default. Remove any existing instantiators whose
- tag set is the same as TAG-SET; then put the new instantiator
- at the beginning of the current list.
+ - Variable: fundamental-mode-abbrev-table
+ This is the local abbrev table used in Fundamental mode; in other
+ words, it is the local abbrev table in all buffers in Fundamental
+ mode.
- `remove-tag-set-append'
- Remove any existing instantiators whose tag set is the same as
- TAG-SET; then put the new instantiator at the end of the
- current list.
-
- `remove-locale'
- Remove all previous instantiators for this locale before
- adding the new spec.
-
- `remove-locale-type'
- Remove all specifications for all locales of the same type as
- LOCALE (this includes LOCALE itself) before adding the new
- spec.
-
- `remove-all'
- Remove all specifications from the specifier before adding
- the new spec.
-
- `remove-tag-set-prepend' is the default.
-
- You can retrieve the specifications for a particular locale or
- locale type with the function `specifier-spec-list' or
- `specifier-specs'.
-
- - Function: add-spec-list-to-specifier specifier spec-list &optional
- how-to-add
- This function adds a "spec-list" (a list of specifications) to
- SPECIFIER. The format of a spec-list is
-
- `((LOCALE (TAG-SET . INSTANTIATOR) ...) ...)'
-
- where
-
- * LOCALE := a window, a buffer, a frame, a device, or `global'
-
- * TAG-SET := an unordered list of zero or more TAGS, each of
- which is a symbol
-
- * TAG := a device class (*note Consoles and Devices::), a
- device type, or a tag defined with `define-specifier-tag'
-
- * INSTANTIATOR := format determined by the type of specifier
-
- The pair `(TAG-SET . INSTANTIATOR)' is called an "inst-pair". A
- list of inst-pairs is called an "inst-list". The pair `(LOCALE .
- INST-LIST)' is called a "specification". A spec-list, then, can
- be viewed as a list of specifications.
-
- HOW-TO-ADD specifies how to combine the new specifications with
- the existing ones, and has the same semantics as for
- `add-spec-to-specifier'.
-
- In many circumstances, the higher-level function `set-specifier' is
- more convenient and should be used instead.
-
- - Macro: let-specifier specifier-list &rest body
- This special form temporarily adds specifications to specifiers,
- evaluates forms in BODY and restores the specifiers to their
- previous states. The specifiers and their temporary
- specifications are listed in SPECIFIER-LIST.
-
- The format of SPECIFIER-LIST is
-
- ((SPECIFIER VALUE &optional LOCALE TAG-SET HOW-TO-ADD) ...)
-
- SPECIFIER is the specifier to be temporarily modified. VALUE is
- the instantiator to be temporarily added to specifier in LOCALE.
- LOCALE, TAG-SET and HOW-TO-ADD have the same meaning as in
- `add-spec-to-specifier'.
-
- This special form is implemented as a macro; the code resulting
- from macro expansion will add specifications to specifiers using
- `add-spec-to-specifier'. After forms in BODY are evaluated, the
- temporary specifications are removed and old specifier spec-lists
- are restored.
-
- LOCALE, TAG-SET and HOW-TO-ADD may be omitted, and default to
- `nil'. The value of the last form in BODY is returned.
-
- NOTE: If you want the specifier's instance to change in all
- circumstances, use `(selected-window)' as the LOCALE. If LOCALE
- is `nil' or omitted, it defaults to `global'.
+ - Variable: text-mode-abbrev-table
+ This is the local abbrev table used in Text mode.
- The following example removes the 3D modeline effect in the
- currently selected window for the duration of a second:
+ - Variable: c-mode-abbrev-table
+ This is the local abbrev table used in C mode.
- (let-specifier ((modeline-shadow-thickness 0 (selected-window)))
- (sit-for 1))
+ - Variable: lisp-mode-abbrev-table
+ This is the local abbrev table used in Lisp mode and Emacs Lisp
+ mode.
- - Function: set-specifier specifier value &optional how-to-add
- This function adds some specifications to SPECIFIER. VALUE can be
- a single instantiator or tagged instantiator (added as a global
- specification), a list of tagged and/or untagged instantiators
- (added as a global specification), a cons of a locale and
- instantiator or locale and instantiator list, a list of such
- conses, or nearly any other reasonable form. More specifically,
- VALUE can be anything accepted by `canonicalize-spec-list'.
+\1f
+File: lispref.info, Node: Extents, Next: Specifiers, Prev: Abbrevs, Up: Top
- HOW-TO-ADD is the same as in `add-spec-to-specifier'.
+Extents
+*******
- Note that `set-specifier' is exactly complementary to
- `specifier-specs' except in the case where SPECIFIER has no specs
- at all in it but `nil' is a valid instantiator (in that case,
- `specifier-specs' will return `nil' (meaning no specs) and
- `set-specifier' will interpret the `nil' as meaning "I'm adding a
- global instantiator and its value is `nil'"), or in strange cases
- where there is an ambiguity between a spec-list and an inst-list,
- etc. (The built-in specifier types are designed in such a way as
- to avoid any such ambiguities.)
+ An "extent" is a region of text (a start position and an end
+position) that is displayed in a particular face and can have certain
+other properties such as being read-only. Extents can overlap each
+other. XEmacs efficiently handles buffers with large numbers of
+extents in them.
- If you want to work with spec-lists, you should probably not use
- these functions, but should use the lower-level functions
- `specifier-spec-list' and `add-spec-list-to-specifier'. These
- functions always work with fully-qualified spec-lists; thus, there
- is no ambiguity.
+ - Function: extentp object
+ This returns `t' if OBJECT is an extent.
- - Function: canonicalize-inst-pair inst-pair specifier-type &optional
- noerror
- This function canonicalizes the given INST-PAIR.
+* Menu:
- SPECIFIER-TYPE specifies the type of specifier that this SPEC-LIST
- will be used for.
+* Intro to Extents:: Extents are regions over a buffer or string.
+* Creating and Modifying Extents::
+ Basic extent functions.
+* Extent Endpoints:: Accessing and setting the bounds of an extent.
+* Finding Extents:: Determining which extents are in an object.
+* Mapping Over Extents:: More sophisticated functions for extent scanning.
+* Extent Properties:: Extents have built-in and user-definable properties.
+* Detached Extents:: Extents that are not in a buffer.
+* Extent Parents:: Inheriting properties from another extent.
+* Duplicable Extents:: Extents can be marked to be copied into strings.
+* Extents and Events:: Extents can interact with the keyboard and mouse.
+* Atomic Extents:: Treating a block of text as a single entity.
- Canonicalizing means converting to the full form for an inst-pair,
- i.e. `(TAG-SET . INSTANTIATOR)'. A single, untagged instantiator
- is given a tag set of `nil' (the empty set), and a single tag is
- converted into a tag set consisting only of that tag.
+\1f
+File: lispref.info, Node: Intro to Extents, Next: Creating and Modifying Extents, Up: Extents
+
+Introduction to Extents
+=======================
+
+ An extent is a region of text within a buffer or string that has
+certain properties associated with it. The properties of an extent
+primarily affect the way the text contained in the extent is displayed.
+Extents can freely overlap each other in a buffer or string. Extents
+are invisible to functions that merely examine the text of a buffer or
+string.
+
+ _Please note:_ An alternative way to add properties to a buffer or
+string is to use text properties. *Note Text Properties::.
+
+ An extent is logically a Lisp object consisting of a start position,
+an end position, a buffer or string to which these positions refer, and
+a property list. As text is inserted into a buffer, the start and end
+positions of the extent are automatically adjusted as necessary to keep
+the extent referring to the same text in the buffer. If text is
+inserted at the boundary of an extent, the extent's `start-open' and
+`end-open' properties control whether the text is included as part of
+the extent. If the text bounded by an extent is deleted, the extent
+becomes "detached"; its start and end positions are no longer
+meaningful, but it maintains all its other properties and can later be
+reinserted into a buffer. (None of these considerations apply to
+strings, because text cannot be inserted into or deleted from a string.)
+
+ Each extent has a face or list of faces associated with it, which
+controls the way in which the text bounded by the extent is displayed.
+If an extent's face is `nil' or its properties are partially undefined,
+the corresponding properties from the default face for the frame is
+used. If two or more extents overlap, or if a list of more than one
+face is specified for a particular extent, the corresponding faces are
+merged to determine the text's displayed properties. Every extent has
+a "priority" that determines which face takes precedence if the faces
+conflict. (If two extents have the same priority, the one that comes
+later in the display order takes precedence. *Note display order:
+Extent Endpoints.) Higher-numbered priority values correspond to a
+higher priority, and priority values can be negative. Every extent is
+created with a priority of 0, but this can be changed with
+`set-extent-priority'. Within a single extent with a list of faces,
+faces earlier in the list have a higher priority than faces later in
+the list.
+
+ Extents can be set to respond specially to key and mouse events
+within the extent. An extent's `keymap' property controls the effect of
+key and mouse strokes within the extent's text, and the `mouse-face'
+property controls whether the extent is highlighted when the mouse moves
+over it. *Note Extents and Events::.
+
+ An extent can optionally have a "begin-glyph" or "end-glyph"
+associated with it. A begin-glyph or end-glyph is a pixmap or string
+that will be displayed either at the start or end of an extent or in the
+margin of the line that the start or end of the extent lies in,
+depending on the extent's layout policy. Begin-glyphs and end-glyphs
+are used to implement annotations, and you should use the annotation API
+functions in preference to the lower-level extent functions. For more
+information, *Note Annotations::.
+
+ If an extent has its `detachable' property set, it will become
+"detached" (i.e. no longer in the buffer) when all its text is deleted.
+Otherwise, it will simply shrink down to zero-length and sit in the
+same place in the buffer. By default, the `detachable' property is set
+on newly-created extents. *Note Detached Extents::.
+
+ If an extent has its `duplicable' property set, it will be
+remembered when a string is created from text bounded by the extent.
+When the string is re-inserted into a buffer, the extent will also be
+re-inserted. This mechanism is used in the kill, yank, and undo
+commands. *Note Duplicable Extents::.
- If NOERROR is non-`nil', signal an error if the inst-pair is
- invalid; otherwise return `t'.
+\1f
+File: lispref.info, Node: Creating and Modifying Extents, Next: Extent Endpoints, Prev: Intro to Extents, Up: Extents
- - Function: canonicalize-inst-list inst-list specifier-type &optional
- noerror
- This function canonicalizes the given INST-LIST (a list of
- inst-pairs).
-
- SPECIFIER-TYPE specifies the type of specifier that this INST-LIST
- will be used for.
-
- Canonicalizing means converting to the full form for an inst-list,
- i.e. `((TAG-SET . INSTANTIATOR) ...)'. This function accepts a
- single inst-pair or any abbreviation thereof or a list of
- (possibly abbreviated) inst-pairs. (See `canonicalize-inst-pair'.)
-
- If NOERROR is non-`nil', signal an error if the inst-list is
- invalid; otherwise return `t'.
-
- - Function: canonicalize-spec spec specifier-type &optional noerror
- This function canonicalizes the given SPEC (a specification).
-
- SPECIFIER-TYPE specifies the type of specifier that this SPEC-LIST
- will be used for.
-
- Canonicalizing means converting to the full form for a spec, i.e.
- `(LOCALE (TAG-SET . INSTANTIATOR) ...)'. This function accepts a
- possibly abbreviated inst-list or a cons of a locale and a
- possibly abbreviated inst-list. (See `canonicalize-inst-list'.)
-
- If NOERROR is `nil', signal an error if the specification is
- invalid; otherwise return `t'.
+Creating and Modifying Extents
+==============================
- - Function: canonicalize-spec-list spec-list specifier-type &optional
- noerror
- This function canonicalizes the given SPEC-LIST (a list of
- specifications).
-
- SPECIFIER-TYPE specifies the type of specifier that this SPEC-LIST
- will be used for.
-
- Canonicalizing means converting to the full form for a spec-list,
- i.e. `((LOCALE (TAG-SET . INSTANTIATOR) ...) ...)'. This
- function accepts a possibly abbreviated specification or a list of
- such things. (See `canonicalize-spec'.) This is the function used
- to convert spec-lists accepted by `set-specifier' and such into a
- form suitable for `add-spec-list-to-specifier'.
-
- This function tries extremely hard to resolve any ambiguities, and
- the built-in specifier types (font, image, toolbar, etc.) are
- designed so that there won't be any ambiguities.
-
- If NOERROR is `nil', signal an error if the spec-list is invalid;
- otherwise return `t'.
+ - Function: make-extent from to &optional buffer-or-string
+ This function makes an extent for the range [FROM, TO) in
+ BUFFER-OR-STRING (a buffer or string). BUFFER-OR-STRING defaults
+ to the current buffer. Insertions at point TO will be outside of
+ the extent; insertions at FROM will be inside the extent, causing
+ the extent to grow (*note Extent Endpoints::). This is the same
+ way that markers behave. The extent is initially detached if both
+ FROM and TO are `nil', and in this case BUFFER-OR-STRING defaults
+ to `nil', meaning the extent is in no buffer or string (*note
+ Detached Extents::).
+
+ - Function: delete-extent extent
+ This function removes EXTENT from its buffer and destroys it.
+ This does not modify the buffer's text, only its display
+ properties. The extent cannot be used thereafter. To remove an
+ extent in such a way that it can be re-inserted later, use
+ `detach-extent'. *Note Detached Extents::.
+
+ - Function: extent-object extent
+ This function returns the buffer or string that EXTENT is in. If
+ the return value is `nil', this means that the extent is detached;
+ however, a detached extent will not necessarily return a value of
+ `nil'.
+
+ - Function: extent-live-p object
+ This function returns `t' if OBJECT is an extent that has not been
+ deleted, and `nil' otherwise.
\1f
-File: lispref.info, Node: Retrieving Specifications, Next: Specifier Tag Functions, Prev: Adding Specifications, Up: Specifiers
-
-Retrieving the Specifications from a Specifier
-==============================================
-
- - Function: specifier-spec-list specifier &optional locale tag-set
- exact-p
- This function returns the spec-list of specifications for
- SPECIFIER in LOCALE.
-
- If LOCALE is a particular locale (a window, buffer, frame, device,
- or the symbol `global'), a spec-list consisting of the
- specification for that locale will be returned.
-
- If LOCALE is a locale type (i.e. a symbol `window', `buffer',
- `frame', or `device'), a spec-list of the specifications for all
- locales of that type will be returned.
-
- If LOCALE is `nil' or the symbol `all', a spec-list of all
- specifications in SPECIFIER will be returned.
-
- LOCALE can also be a list of locales, locale types, and/or `all';
- the result is as if `specifier-spec-list' were called on each
- element of the list and the results concatenated together.
-
- Only instantiators where TAG-SET (a list of zero or more tags) is
- a subset of (or possibly equal to) the instantiator's tag set are
- returned. (The default value of` nil' is a subset of all tag sets,
- so in this case no instantiators will be screened out.) If EXACT-P
- is non-`nil', however, TAG-SET must be equal to an instantiator's
- tag set for the instantiator to be returned.
-
- - Function: specifier-specs specifier &optional locale tag-set exact-p
- This function returns the specification(s) for SPECIFIER in LOCALE.
-
- If LOCALE is a single locale or is a list of one element
- containing a single locale, then a "short form" of the
- instantiators for that locale will be returned. Otherwise, this
- function is identical to `specifier-spec-list'.
-
- The "short form" is designed for readability and not for ease of
- use in Lisp programs, and is as follows:
-
- 1. If there is only one instantiator, then an inst-pair (i.e.
- cons of tag and instantiator) will be returned; otherwise a
- list of inst-pairs will be returned.
-
- 2. For each inst-pair returned, if the instantiator's tag is
- `any', the tag will be removed and the instantiator itself
- will be returned instead of the inst-pair.
-
- 3. If there is only one instantiator, its value is `nil', and
- its tag is `any', a one-element list containing `nil' will be
- returned rather than just `nil', to distinguish this case
- from there being no instantiators at all.
-
-
- - Function: specifier-fallback specifier
- This function returns the fallback value for SPECIFIER. Fallback
- values are provided by the C code for certain built-in specifiers
- to make sure that instancing won't fail even if all specs are
- removed from the specifier, or to implement simple inheritance
- behavior (e.g. this method is used to ensure that faces other than
- `default' inherit their attributes from `default'). By design,
- you cannot change the fallback value, and specifiers created with
- `make-specifier' will never have a fallback (although a similar,
- Lisp-accessible capability may be provided in the future to allow
- for inheritance).
-
- The fallback value will be an inst-list that is instanced like any
- other inst-list, a specifier of the same type as SPECIFIER
- (results in inheritance), or `nil' for no fallback.
-
- When you instance a specifier, you can explicitly request that the
- fallback not be consulted. (The C code does this, for example, when
- merging faces.) See `specifier-instance'.
+File: lispref.info, Node: Extent Endpoints, Next: Finding Extents, Prev: Creating and Modifying Extents, Up: Extents
+
+Extent Endpoints
+================
+
+ Every extent has a start position and an end position, and logically
+affects the characters between those positions. Normally the start and
+end positions must both be valid positions in the extent's buffer or
+string. However, both endpoints can be `nil', meaning the extent is
+detached. *Note Detached Extents::.
+
+ Whether the extent overlaps its endpoints is governed by its
+`start-open' and `end-open' properties. Insertion of a character at a
+closed endpoint will expand the extent to include that character;
+insertion at an open endpoint will not. Similarly, functions such as
+`extent-at' that scan over all extents overlapping a particular
+position will include extents with a closed endpoint at that position,
+but not extents with an open endpoint.
+
+ Note that the `start-closed' and `end-closed' properties are
+equivalent to `start-open' and `end-open' with the opposite sense.
+
+ Both endpoints can be equal, in which case the extent includes no
+characters but still exists in the buffer or string. Zero-length
+extents are used to represent annotations (*note Annotations::) and can
+be used as a more powerful form of a marker. Deletion of all the
+characters in an extent may or may not result in a zero-length extent;
+this depends on the `detachable' property (*note Detached Extents::).
+Insertion at the position of a zero-length extent expands the extent if
+both endpoints are closed; goes before the extent if it has the
+`start-open' property; and goes after the extent if it has the
+`end-open' property. Zero-length extents with both the `start-open'
+and `end-open' properties are treated as if their starting point were
+closed. Deletion of a character on a side of a zero-length extent
+whose corresponding endpoint is closed causes the extent to be detached
+if its `detachable' property is set; if the corresponding endpoint is
+open, the extent remains in the buffer, moving as necessary.
+
+ Extents are ordered within a buffer or string by increasing start
+position, and then by decreasing end position (this is called the
+"display order").
+
+ - Function: extent-start-position extent
+ This function returns the start position of EXTENT.
+
+ - Function: extent-end-position extent
+ This function returns the end position of EXTENT.
+
+ - Function: extent-length extent
+ This function returns the length of EXTENT in characters. If the
+ extent is detached, this returns `0'. If the extent is not
+ detached, this is equivalent to
+ (- (extent-end-position EXTENT) (extent-start-position EXTENT))
+
+ - Function: set-extent-endpoints extent start end &optional
+ buffer-or-string
+ This function sets the start and end position of EXTENT to START
+ and END. If both are `nil', this is equivalent to `detach-extent'.
+
+ BUFFER-OR-STRING specifies the new buffer or string that the
+ extent should be in, and defaults to EXTENT's buffer or string.
+ (If `nil', and EXTENT is in no buffer and no string, it defaults
+ to the current buffer.)
+
+ See documentation on `detach-extent' for a discussion of undo
+ recording.
\1f
-File: lispref.info, Node: Specifier Tag Functions, Next: Specifier Instancing Functions, Prev: Retrieving Specifications, Up: Specifiers
-
-Working With Specifier Tags
-===========================
-
- A specifier tag set is an entity that is attached to an instantiator
-and can be used to restrict the scope of that instantiator to a
-particular device class or device type and/or to mark instantiators
-added by a particular package so that they can be later removed.
-
- A specifier tag set consists of a list of zero of more specifier
-tags, each of which is a symbol that is recognized by XEmacs as a tag.
-(The valid device types and device classes are always tags, as are any
-tags defined by `define-specifier-tag'.) It is called a "tag set" (as
-opposed to a list) because the order of the tags or the number of times
-a particular tag occurs does not matter.
-
- Each tag has a predicate associated with it, which specifies whether
-that tag applies to a particular device. The tags which are device
-types and classes match devices of that type or class. User-defined
-tags can have any predicate, or none (meaning that all devices match).
-When attempting to instance a specifier, a particular instantiator is
-only considered if the device of the domain being instanced over matches
-all tags in the tag set attached to that instantiator.
-
- Most of the time, a tag set is not specified, and the instantiator
-gets a null tag set, which matches all devices.
-
- - Function: valid-specifier-tag-p tag
- This function returns non-`nil' if TAG is a valid specifier tag.
-
- - Function: valid-specifier-tag-set-p tag-set
- This function returns non-`nil' if TAG-SET is a valid specifier
- tag set.
-
- - Function: canonicalize-tag-set tag-set
- This function canonicalizes the given tag set. Two canonicalized
- tag sets can be compared with `equal' to see if they represent the
- same tag set. (Specifically, canonicalizing involves sorting by
- symbol name and removing duplicates.)
-
- - Function: device-matches-specifier-tag-set-p device tag-set
- This function returns non-`nil' if DEVICE matches specifier tag
- set TAG-SET. This means that DEVICE matches each tag in the tag
- set.
-
- - Function: define-specifier-tag tag &optional predicate
- This function defines a new specifier tag. If PREDICATE is
- specified, it should be a function of one argument (a device) that
- specifies whether the tag matches that particular device. If
- PREDICATE is omitted, the tag matches all devices.
-
- You can redefine an existing user-defined specifier tag. However,
- you cannot redefine the built-in specifier tags (the device types
- and classes) or the symbols `nil', `t', `all', or `global'.
-
- - Function: device-matching-specifier-tag-list &optional device
- This function returns a list of all specifier tags matching
- DEVICE. DEVICE defaults to the selected device if omitted.
-
- - Function: specifier-tag-list
- This function returns a list of all currently-defined specifier
- tags. This includes the built-in ones (the device types and
- classes).
-
- - Function: specifier-tag-predicate tag
- This function returns the predicate for the given specifier tag.
+File: lispref.info, Node: Finding Extents, Next: Mapping Over Extents, Prev: Extent Endpoints, Up: Extents
+
+Finding Extents
+===============
+
+ The following functions provide a simple way of determining the
+extents in a buffer or string. A number of more sophisticated
+primitives for mapping over the extents in a range of a buffer or string
+are also provided (*note Mapping Over Extents::). When reading through
+this section, keep in mind the way that extents are ordered (*note
+Extent Endpoints::).
+
+ - Function: extent-list &optional buffer-or-string from to flags
+ property value
+ This function returns a list of the extents in BUFFER-OR-STRING.
+ BUFFER-OR-STRING defaults to the current buffer if omitted. FROM
+ and TO can be used to limit the range over which extents are
+ returned; if omitted, all extents in the buffer or string are
+ returned.
+
+ More specifically, if a range is specified using FROM and TO, only
+ extents that overlap the range (i.e. begin or end inside of the
+ range) are included in the list. FROM and TO default to the
+ beginning and end of BUFFER-OR-STRING, respectively.
+
+ FLAGS controls how end cases are treated. For a discussion of
+ this, and exactly what "overlap" means, see `map-extents'.
+
+ The optional arguments PROPERTY and VALUE can be used to further
+ restrict which extents are returned. They have the same meaning
+ as for `map-extents'.
+
+ If you want to map a function over the extents in a buffer or
+ string, consider using `map-extents' or `mapcar-extents' instead.
+
+ See also the function `extents-at'.
+
+ Functions that create extents must be prepared for the possibility
+that there are other extents in the same area, created by other
+functions. To deal with this, functions typically mark their own
+extents by setting a particular property on them. The following
+function makes it easier to locate those extents.
+
+ - Function: extent-at pos &optional object property before at-flag
+ This function finds the "smallest" extent (i.e., the last one in
+ the display order) at (i.e., overlapping) POS in OBJECT (a buffer
+ or string) having PROPERTY set. OBJECT defaults to the current
+ buffer. PROPERTY defaults to `nil', meaning that any extent will
+ do. Returns `nil' if there is no matching extent at POS. If the
+ fourth argument BEFORE is not `nil', it must be an extent; any
+ returned extent will precede that extent. This feature allows
+ `extent-at' to be used by a loop over extents.
+
+ AT-FLAG controls how end cases are handled (i.e. what "at" really
+ means), and should be one of:
+
+ `nil'
+
+ `after'
+ An extent is at POS if it covers the character after POS.
+ This is consistent with the way that text properties work.
+
+ `before'
+ An extent is at POS if it covers the character before POS.
+
+ `at'
+ An extent is at POS if it overlaps or abuts POS. This
+ includes all zero-length extents at POS.
+
+ Note that in all cases, the start-openness and end-openness of the
+ extents considered is ignored. If you want to pay attention to
+ those properties, you should use `map-extents', which gives you
+ more control.
+
+ The following low-level functions are provided for explicitly
+traversing the extents in a buffer according to the display order.
+These functions are mostly intended for debugging--in normal operation,
+you should probably use `mapcar-extents' or `map-extents', or loop
+using the BEFORE argument to `extent-at', rather than creating a loop
+using `next-extent'.
+
+ - Function: next-extent extent
+ Given an extent EXTENT, this function returns the next extent in
+ the buffer or string's display order. If EXTENT is a buffer or
+ string, this returns the first extent in the buffer or string.
+
+ - Function: previous-extent extent
+ Given an extent EXTENT, this function returns the previous extent
+ in the buffer or string's display order. If EXTENT is a buffer or
+ string, this returns the last extent in the buffer or string.
\1f
-File: lispref.info, Node: Specifier Instancing Functions, Next: Specifier Example, Prev: Specifier Tag Functions, Up: Specifiers
-
-Functions for Instancing a Specifier
-====================================
-
- - Function: specifier-instance specifier &optional domain default
- no-fallback
- This function instantiates SPECIFIER (return its value) in DOMAIN.
- If no instance can be generated for this domain, return DEFAULT.
-
- DOMAIN should be a window, frame, or device. Other values that
- are legal as a locale (e.g. a buffer) are not valid as a domain
- because they do not provide enough information to identify a
- particular device (see `valid-specifier-domain-p'). DOMAIN
- defaults to the selected window if omitted.
-
- "Instantiating" a specifier in a particular domain means
- determining the specifier's "value" in that domain. This is
- accomplished by searching through the specifications in the
- specifier that correspond to all locales that can be derived from
- the given domain, from specific to general. In most cases, the
- domain is an Emacs window. In that case specifications are
- searched for as follows:
-
- 1. A specification whose locale is the window itself;
-
- 2. A specification whose locale is the window's buffer;
-
- 3. A specification whose locale is the window's frame;
-
- 4. A specification whose locale is the window's frame's device;
-
- 5. A specification whose locale is the symbol `global'.
-
- If all of those fail, then the C-code-provided fallback value for
- this specifier is consulted (see `specifier-fallback'). If it is
- an inst-list, then this function attempts to instantiate that list
- just as when a specification is located in the first five steps
- above. If the fallback is a specifier, `specifier-instance' is
- called recursively on this specifier and the return value used.
- Note, however, that if the optional argument NO-FALLBACK is
- non-`nil', the fallback value will not be consulted.
-
- Note that there may be more than one specification matching a
- particular locale; all such specifications are considered before
- looking for any specifications for more general locales. Any
- particular specification that is found may be rejected because it
- is tagged to a particular device class (e.g. `color') or device
- type (e.g. `x') or both and the device for the given domain does
- not match this, or because the specification is not valid for the
- device of the given domain (e.g. the font or color name does not
- exist for this particular X server).
-
- The returned value is dependent on the type of specifier. For
- example, for a font specifier (as returned by the `face-font'
- function), the returned value will be a font-instance object. For
- images, the returned value will be a string, pixmap, or subwindow.
-
- - Function: specifier-instance-from-inst-list specifier domain
- inst-list &optional default
- This function attempts to convert a particular inst-list into an
- instance. This attempts to instantiate INST-LIST in the given
- DOMAIN, as if INST-LIST existed in a specification in SPECIFIER.
- If the instantiation fails, DEFAULT is returned. In most
- circumstances, you should not use this function; use
- `specifier-instance' instead.
+File: lispref.info, Node: Mapping Over Extents, Next: Extent Properties, Prev: Finding Extents, Up: Extents
+
+Mapping Over Extents
+====================
+
+ The most basic and general function for mapping over extents is
+called `map-extents'. You should read through the definition of this
+function to familiarize yourself with the concepts and optional
+arguments involved. However, in practice you may find it more
+convenient to use the function `mapcar-extents' or to create a loop
+using the `before' argument to `extent-at' (*note Finding Extents::).
+
+ - Function: map-extents function &optional object from to maparg flags
+ property value
+ This function maps FUNCTION over the extents which overlap a
+ region in OBJECT. OBJECT is normally a buffer or string but could
+ be an extent (see below). The region is normally bounded by
+ [FROM, TO) (i.e. the beginning of the region is closed and the end
+ of the region is open), but this can be changed with the FLAGS
+ argument (see below for a complete discussion).
+
+ FUNCTION is called with the arguments (extent, MAPARG). The
+ arguments OBJECT, FROM, TO, MAPARG, and FLAGS are all optional and
+ default to the current buffer, the beginning of OBJECT, the end of
+ OBJECT, `nil', and `nil', respectively. `map-extents' returns the
+ first non-`nil' result produced by FUNCTION, and no more calls to
+ FUNCTION are made after it returns non-`nil'.
+
+ If OBJECT is an extent, FROM and TO default to the extent's
+ endpoints, and the mapping omits that extent and its predecessors.
+ This feature supports restarting a loop based on `map-extents'.
+ Note: OBJECT must be attached to a buffer or string, and the
+ mapping is done over that buffer or string.
+
+ An extent overlaps the region if there is any point in the extent
+ that is also in the region. (For the purpose of overlap,
+ zero-length extents and regions are treated as closed on both ends
+ regardless of their endpoints' specified open/closedness.) Note
+ that the endpoints of an extent or region are considered to be in
+ that extent or region if and only if the corresponding end is
+ closed. For example, the extent [5,7] overlaps the region [2,5]
+ because 5 is in both the extent and the region. However, (5,7]
+ does not overlap [2,5] because 5 is not in the extent, and neither
+ [5,7] nor (5,7] overlaps the region [2,5) because 5 is not in the
+ region.
+
+ The optional FLAGS can be a symbol or a list of one or more
+ symbols, modifying the behavior of `map-extents'. Allowed symbols
+ are:
+
+ `end-closed'
+ The region's end is closed.
+
+ `start-open'
+ The region's start is open.
+
+ `all-extents-closed'
+ Treat all extents as closed on both ends for the purpose of
+ determining whether they overlap the region, irrespective of
+ their actual open- or closedness.
+
+ `all-extents-open'
+ Treat all extents as open on both ends.
+
+ `all-extents-closed-open'
+ Treat all extents as start-closed, end-open.
+
+ `all-extents-open-closed'
+ Treat all extents as start-open, end-closed.
+
+ `start-in-region'
+ In addition to the above conditions for extent overlap, the
+ extent's start position must lie within the specified region.
+ Note that, for this condition, open start positions are
+ treated as if 0.5 was added to the endpoint's value, and open
+ end positions are treated as if 0.5 was subtracted from the
+ endpoint's value.
+
+ `end-in-region'
+ The extent's end position must lie within the region.
+
+ `start-and-end-in-region'
+ Both the extent's start and end positions must lie within the
+ region.
+
+ `start-or-end-in-region'
+ Either the extent's start or end position must lie within the
+ region.
+
+ `negate-in-region'
+ The condition specified by a `*-in-region' flag must _not_
+ hold for the extent to be considered.
+
+ At most one of `all-extents-closed', `all-extents-open',
+ `all-extents-closed-open', and `all-extents-open-closed' may be
+ specified.
+
+ At most one of `start-in-region', `end-in-region',
+ `start-and-end-in-region', and `start-or-end-in-region' may be
+ specified.
+
+ If optional arg PROPERTY is non-`nil', only extents with that
+ property set on them will be visited. If optional arg VALUE is
+ non-`nil', only extents whose value for that property is `eq' to
+ VALUE will be visited.
+
+ If you want to map over extents and accumulate a list of results,
+the following function may be more convenient than `map-extents'.
+
+ - Function: mapcar-extents function &optional predicate
+ buffer-or-string from to flags property value
+ This function applies FUNCTION to all extents which overlap a
+ region in BUFFER-OR-STRING. The region is delimited by FROM and
+ TO. FUNCTION is called with one argument, the extent. A list of
+ the values returned by FUNCTION is returned. An optional
+ PREDICATE may be used to further limit the extents over which
+ FUNCTION is mapped. The optional arguments FLAGS, PROPERTY, and
+ VALUE may also be used to control the extents passed to PREDICATE
+ or FUNCTION, and have the same meaning as in `map-extents'.
+
+ - Function: map-extent-children function &optional object from to
+ maparg flags property value
+ This function is similar to `map-extents', but differs in that:
+
+ * It only visits extents which start in the given region.
+
+ * After visiting an extent E, it skips all other extents which
+ start inside E but end before E's end.
+
+ Thus, this function may be used to walk a tree of extents in a
+ buffer:
+ (defun walk-extents (buffer &optional ignore)
+ (map-extent-children 'walk-extents buffer))
+
+ - Function: extent-in-region-p extent &optional from to flags
+ This function returns `t' if `map-extents' would visit EXTENT if
+ called with the given arguments.
\1f
-File: lispref.info, Node: Specifier Example, Next: Creating Specifiers, Prev: Specifier Instancing Functions, Up: Specifiers
+File: lispref.info, Node: Extent Properties, Next: Detached Extents, Prev: Mapping Over Extents, Up: Extents
+
+Properties of Extents
+=====================
+
+ Each extent has a property list associating property names with
+values. Some property names have predefined meanings, and can usually
+only assume particular values. Assigning other values to such a
+property either cause the value to be converted into a legal value
+(e.g., assigning anything but `nil' to a Boolean property will cause
+the value of `t' to be assigned to the property) or will cause an
+error. Property names without predefined meanings can be assigned any
+value. An undefined property is equivalent to a property with a value
+of `nil', or with a particular default value in the case of properties
+with predefined meanings. Note that, when an extent is created, the
+`end-open' and `detachable' properties are set on it.
+
+ If an extent has a parent, all of its properties actually derive
+from that parent (or from the root ancestor if the parent in turn has a
+parent), and setting a property of the extent actually sets that
+property on the parent. *Note Extent Parents::.
+
+ - Function: extent-property extent property &optional default
+ This function returns EXTENT's value for PROPERTY, or DEFAULT if
+ no such property exists.
+
+ - Function: extent-properties extent
+ This function returns a list of all of EXTENT's properties that do
+ not have the value of `nil' (or the default value, for properties
+ with predefined meanings).
+
+ - Function: set-extent-property extent property value
+ This function sets PROPERTY to VALUE in EXTENT. (If PROPERTY has a
+ predefined meaning, only certain values are allowed, and some
+ values may be converted to others before being stored.)
+
+ - Function: set-extent-properties extent plist
+ Change some properties of EXTENT. PLIST is a property list. This
+ is useful to change many extent properties at once.
+
+ The following table lists the properties with predefined meanings,
+along with their allowable values.
+
+`detached'
+ (Boolean) Whether the extent is detached. Setting this is the
+ same as calling `detach-extent'. *Note Detached Extents::.
+
+`destroyed'
+ (Boolean) Whether the extent has been deleted. Setting this is
+ the same as calling `delete-extent'.
+
+`priority'
+ (integer) The extent's redisplay priority. Defaults to 0. *Note
+ priority: Intro to Extents. This property can also be set with
+ `set-extent-priority' and accessed with `extent-priority'.
+
+`start-open'
+ (Boolean) Whether the start position of the extent is open,
+ meaning that characters inserted at that position go outside of
+ the extent. *Note Extent Endpoints::.
+
+`start-closed'
+ (Boolean) Same as `start-open' but with the opposite sense.
+ Setting this property clears `start-open' and vice-versa.
+
+`end-open'
+ (Boolean) Whether the end position of the extent is open, meaning
+ that characters inserted at that position go outside of the
+ extent. This is `t' by default. *Note Extent Endpoints::.
+
+`end-closed'
+ (Boolean) Same as `end-open' but with the opposite sense. Setting
+ this property clears `end-open' and vice-versa.
+
+`read-only'
+ (Boolean) Whether text within this extent will be unmodifiable.
+
+`face'
+ (face, face name, list of faces or face names, or `nil') The face
+ in which to display the extent's text. This property can also be
+ set with `set-extent-face' and accessed with `extent-face'. Note
+ that if a list of faces is specified, the faces are merged
+ together, with faces earlier in the list having priority over
+ faces later in the list.
+
+`mouse-face'
+ (face, face name, list of faces or face names, or `nil') The face
+ used to display the extent when the mouse moves over it. This
+ property can also be set with `set-extent-mouse-face' and accessed
+ with `extent-mouse-face'. Note that if a list of faces is
+ specified, the faces are merged together, with faces earlier in
+ the list having priority over faces later in the list. *Note
+ Extents and Events::.
+
+`pointer'
+ (pointer glyph) The glyph used as the pointer when the mouse
+ moves over the extent. This takes precedence over the
+ `text-pointer-glyph' and `nontext-pointer-glyph' variables. If
+ for any reason this glyph is an invalid pointer, the standard
+ glyphs will be used as fallbacks. *Note Mouse Pointer::.
+
+`detachable'
+ (Boolean) Whether this extent becomes detached when all of the
+ text it covers is deleted. This is `t' by default. *Note
+ Detached Extents::.
+
+`duplicable'
+ (Boolean) Whether this extent should be copied into strings, so
+ that kill, yank, and undo commands will restore or copy it. *Note
+ Duplicable Extents::.
+
+`unique'
+ (Boolean) Meaningful only in conjunction with `duplicable'. When
+ this is set, there may be only one instance of this extent
+ attached at a time. *Note Duplicable Extents::.
+
+`invisible'
+ (Boolean) If `t', text under this extent will not be displayed -
+ it will look as if the text is not there at all.
+
+`keymap'
+ (keymap or `nil') This keymap is consulted for mouse clicks on this
+ extent or keypresses made while `point' is within the extent.
+ *Note Extents and Events::.
+
+`copy-function'
+ This is a hook that is run when a duplicable extent is about to be
+ copied from a buffer to a string (or the kill ring). *Note
+ Duplicable Extents::.
+
+`paste-function'
+ This is a hook that is run when a duplicable extent is about to be
+ copied from a string (or the kill ring) into a buffer. *Note
+ Duplicable Extents::.
+
+`begin-glyph'
+ (glyph or `nil') This extent's begin glyph. *Note Annotations::.
+
+`end-glyph'
+ (glyph or `nil') This extent's end glyph. *Note Annotations::.
+
+`begin-glyph-layout'
+ (`text', `whitespace', `inside-margin', or `outside-margin') The
+ layout policy for this extent's begin glyph. Defaults to `text'.
+ *Note Annotations::.
+
+`end-glyph-layout'
+ (`text', `whitespace', `inside-margin', or `outside-margin') The
+ layout policy for this extent's end glyph. Defaults to `text'.
+ *Note Annotations::.
+
+`initial-redisplay-function'
+ (any funcallable object) The function to be called the first time
+ (a part of) the extent is redisplayed. It will be called with the
+ extent as its argument.
+
+ This is used by `lazy-shot' to implement lazy font-locking. The
+ functionality is still experimental, and may change without further
+ notice.
+
+ The following convenience functions are provided for accessing
+particular properties of an extent.
+
+ - Function: extent-face extent
+ This function returns the `face' property of EXTENT. This might
+ also return a list of face names. Do not modify this list
+ directly! Instead, use `set-extent-face'.
+
+ Note that you can use `eq' to compare lists of faces as returned
+ by `extent-face'. In other words, if you set the face of two
+ different extents to two lists that are `equal' but not `eq', then
+ the return value of `extent-face' on the two extents will return
+ the identical list.
+
+ - Function: extent-mouse-face extent
+ This function returns the `mouse-face' property of EXTENT. This
+ might also return a list of face names. Do not modify this list
+ directly! Instead, use `set-extent-mouse-face'.
+
+ Note that you can use `eq' to compare lists of faces as returned
+ by `extent-mouse-face', just like for `extent-face'.
+
+ - Function: extent-priority extent
+ This function returns the `priority' property of EXTENT.
+
+ - Function: extent-keymap extent
+ This function returns the `keymap' property of EXTENT.
+
+ - Function: extent-begin-glyph-layout extent
+ This function returns the `begin-glyph-layout' property of EXTENT,
+ i.e. the layout policy associated with the EXTENT's begin glyph.
+
+ - Function: extent-end-glyph-layout extent
+ This function returns the `end-glyph-layout' property of EXTENT,
+ i.e. the layout policy associated with the EXTENT's end glyph.
+
+ - Function: extent-begin-glyph extent
+ This function returns the `begin-glyph' property of EXTENT, i.e.
+ the glyph object displayed at the beginning of EXTENT. If there
+ is none, `nil' is returned.
+
+ - Function: extent-end-glyph extent
+ This function returns the `end-glyph' property of EXTENT, i.e. the
+ glyph object displayed at the end of EXTENT. If there is none,
+ `nil' is returned.
-Example of Specifier Usage
-==========================
+ The following convenience functions are provided for setting
+particular properties of an extent.
+
+ - Function: set-extent-priority extent priority
+ This function sets the `priority' property of EXTENT to PRIORITY.
+
+ - Function: set-extent-face extent face
+ This function sets the `face' property of EXTENT to FACE.
- Now let us present an example to clarify the theoretical discussions
-we have been through. In this example, we will use the general
-specifier functions for clarity. Keep in mind that many types of
-specifiers, and some other types of objects that are associated with
-specifiers (e.g. faces), provide convenience functions making it easier
-to work with objects of that type.
-
- Let us consider the background color of the default face. A
-specifier is used to specify how that color will appear in different
-domains. First, let's retrieve the specifier:
-
- (setq sp (face-property 'default 'background))
- => #<color-specifier 0x3da>
-
- (specifier-specs sp)
- => ((#<buffer "device.c"> (nil . "forest green"))
- (#<window on "Makefile" 0x8a2b> (nil . "hot pink"))
- (#<x-frame "emacs" 0x4ac> (nil . "puke orange")
- (nil . "moccasin"))
- (#<x-frame "VM" 0x4ac> (nil . "magenta"))
- (global ((tty) . "cyan") (nil . "white"))
- )
-
- Then, say we want to determine what the background color of the
-default face is for the window currently displaying the buffer
-`*scratch*'. We call
-
- (get-buffer-window "*scratch*")
- => #<window on "*scratch*" 0x4ad>
- (window-frame (get-buffer-window "*scratch*"))
- => #<x-frame "emacs" 0x4ac>
- (specifier-instance sp (get-buffer-window "*scratch*"))
- => #<color-instance moccasin 47=(FFFF,E4E4,B5B5) 0x6309>
-
- Note that we passed a window to `specifier-instance', not a buffer.
-We cannot pass a buffer because a buffer by itself does not provide
-enough information. The buffer might not be displayed anywhere at all,
-or could be displayed in many different frames on different devices.
-
- The result is arrived at like this:
-
- 1. First, we look for a specification matching the buffer displayed
- in the window, i.e. `*scratch*'. There are none, so we proceed.
-
- 2. Then, we look for a specification matching the window itself.
- Again, there are none.
-
- 3. Then, we look for a specification matching the window's frame. The
- specification `(#<x-frame "emacs" 0x4ac> . "puke orange")' is
- found. We call the instantiation method for colors, passing it the
- locale we were searching over (i.e. the window, in this case) and
- the instantiator (`"puke orange"'). However, the particular device
- which this window is on (let's say it's an X connection) doesn't
- recognize the color `"puke orange"', so the specification is
- rejected.
-
- 4. So we continue looking for a specification matching the window's
- frame. We find `(#<x-frame "emacs" 0x4ac> . "moccasin")'. Again,
- we call the instantiation method for colors. This time, the X
- server our window is on recognizes the color `moccasin', and so the
- instantiation method succeeds and returns a color instance.
+ - Function: set-extent-mouse-face extent face
+ This function sets the `mouse-face' property of EXTENT to FACE.
-\1f
-File: lispref.info, Node: Creating Specifiers, Next: Specifier Validation Functions, Prev: Specifier Example, Up: Specifiers
+ - Function: set-extent-keymap extent keymap
+ This function sets the `keymap' property of EXTENT to KEYMAP.
+ KEYMAP must be either a keymap object, or `nil'.
-Creating New Specifier Objects
-==============================
+ - Function: set-extent-begin-glyph-layout extent layout
+ This function sets the `begin-glyph-layout' property of EXTENT to
+ LAYOUT.
- - Function: make-specifier type
- This function creates a new specifier.
-
- A specifier is an object that can be used to keep track of a
- property whose value can be per-buffer, per-window, per-frame, or
- per-device, and can further be restricted to a particular
- device-type or device-class. Specifiers are used, for example,
- for the various built-in properties of a face; this allows a face
- to have different values in different frames, buffers, etc. For
- more information, see `specifier-instance', `specifier-specs', and
- `add-spec-to-specifier'; or, for a detailed description of
- specifiers, including how they are instantiated over a particular
- domain (i.e. how their value in that domain is determined), see
- the chapter on specifiers in the XEmacs Lisp Reference Manual.
-
- TYPE specifies the particular type of specifier, and should be one
- of the symbols `generic', `integer', `natnum', `boolean', `color',
- `font', `image', `face-boolean', or `toolbar'.
-
- For more information on particular types of specifiers, see the
- functions `generic-specifier-p', `integer-specifier-p',
- `natnum-specifier-p', `boolean-specifier-p', `color-specifier-p',
- `font-specifier-p', `image-specifier-p',
- `face-boolean-specifier-p', and `toolbar-specifier-p'.
-
- - Function: make-specifier-and-init type spec-list &optional
- dont-canonicalize
- This function creates and initialize a new specifier.
-
- This is a front-end onto `make-specifier' that allows you to create
- a specifier and add specs to it at the same time. TYPE specifies
- the specifier type. SPEC-LIST supplies the specification(s) to be
- added to the specifier. Normally, almost any reasonable
- abbreviation of the full spec-list form is accepted, and is
- converted to the full form; however, if optional argument
- DONT-CANONICALIZE is non-`nil', this conversion is not performed,
- and the SPEC-LIST must already be in full form. See
- `canonicalize-spec-list'.
+ - Function: set-extent-end-glyph-layout extent layout
+ This function sets the `end-glyph-layout' property of EXTENT to
+ LAYOUT.
-\1f
-File: lispref.info, Node: Specifier Validation Functions, Next: Other Specification Functions, Prev: Creating Specifiers, Up: Specifiers
+ - Function: set-extent-begin-glyph extent begin-glyph &optional layout
+ This function sets the `begin-glyph' and `glyph-layout' properties
+ of EXTENT to BEGIN-GLYPH and LAYOUT, respectively. (LAYOUT
+ defaults to `text' if not specified.)
-Functions for Checking the Validity of Specifier Components
-===========================================================
+ - Function: set-extent-end-glyph extent end-glyph &optional layout
+ This function sets the `end-glyph' and `glyph-layout' properties
+ of EXTENT to END-GLYPH and LAYOUT, respectively. (LAYOUT defaults
+ to `text' if not specified.)
- - Function: valid-specifier-domain-p domain
- This function returns non-`nil' if DOMAIN is a valid specifier
- domain. A domain is used to instance a specifier (i.e. determine
- the specifier's value in that domain). Valid domains are a
- window, frame, or device. (`nil' is not valid.)
+ - Function: set-extent-initial-redisplay-function extent function
+ This function sets the `initial-redisplay-function' property of the
+ extent to FUNCTION.
- - Function: valid-specifier-locale-p locale
- This function returns non-`nil' if LOCALE is a valid specifier
- locale. Valid locales are a device, a frame, a window, a buffer,
- and `global'. (`nil' is not valid.)
+\1f
+File: lispref.info, Node: Detached Extents, Next: Extent Parents, Prev: Extent Properties, Up: Extents
+
+Detached Extents
+================
+
+ A detached extent is an extent that is not attached to a buffer or
+string but can be re-inserted. Detached extents have a start position
+and end position of `nil'. Extents can be explicitly detached using
+`detach-extent'. An extent is also detached when all of its characters
+are all killed by a deletion, if its `detachable' property is set; if
+this property is not set, the extent becomes a zero-length extent.
+(Zero-length extents with the `detachable' property set behave
+specially. *Note zero-length extents: Extent Endpoints.)
+
+ - Function: detach-extent extent
+ This function detaches EXTENT from its buffer or string. If
+ EXTENT has the `duplicable' property, its detachment is tracked by
+ the undo mechanism. *Note Duplicable Extents::.
+
+ - Function: extent-detached-p extent
+ This function returns `nil' if EXTENT is detached, and `t'
+ otherwise.
+
+ - Function: copy-extent extent &optional object
+ This function makes a copy of EXTENT. It is initially detached.
+ Optional argument OBJECT defaults to EXTENT's object (normally a
+ buffer or string, but could be `nil').
+
+ - Function: insert-extent extent &optional start end no-hooks object
+ This function inserts EXTENT from START to END in OBJECT (a buffer
+ or string). If EXTENT is detached from a different buffer or
+ string, or in most cases when EXTENT is already attached, the
+ extent will first be copied as if with `copy-extent'. This
+ function operates the same as if `insert' were called on a string
+ whose extent data calls for EXTENT to be inserted, except that if
+ NO-HOOKS is non-`nil', EXTENT's `paste-function' will not be
+ invoked. *Note Duplicable Extents::.
- - Function: valid-specifier-locale-type-p locale-type
- Given a specifier LOCALE-TYPE, this function returns non-nil if it
- is valid. Valid locale types are the symbols `global', `device',
- `frame', `window', and `buffer'. (Note, however, that in functions
- that accept either a locale or a locale type, `global' is
- considered an individual locale.)
+\1f
+File: lispref.info, Node: Extent Parents, Next: Duplicable Extents, Prev: Detached Extents, Up: Extents
- - Function: valid-specifier-type-p specifier-type
- Given a SPECIFIER-TYPE, this function returns non-`nil' if it is
- valid. Valid types are `generic', `integer', `boolean', `color',
- `font', `image', `face-boolean', and `toolbar'.
+Extent Parents
+==============
- - Function: valid-specifier-tag-p tag
- This function returns non-`nil' if TAG is a valid specifier tag.
+ An extent can have a parent extent set for it. If this is the case,
+the extent derives all its properties from that extent and has no
+properties of its own. The only "properties" that the extent keeps are
+the buffer or string it refers to and the start and end points. (More
+correctly, the extent's own properties are shadowed. If you later
+change the extent to have no parent, its own properties will become
+visible again.)
- - Function: valid-instantiator-p instantiator specifier-type
- This function returns non-`nil' if INSTANTIATOR is valid for
- SPECIFIER-TYPE.
+ It is possible for an extent's parent to itself have a parent, and
+so on. Through this, a whole tree of extents can be created, all
+deriving their properties from one root extent. Note, however, that
+you cannot create an inheritance loop--this is explicitly disallowed.
- - Function: valid-inst-list-p inst-list type
- This function returns non-`nil' if INST-LIST is valid for
- specifier type TYPE.
+ Parent extents are used to implement the extents over the modeline.
- - Function: valid-spec-list-p spec-list type
- This function returns non-`nil' if SPEC-LIST is valid for
- specifier type TYPE.
+ - Function: set-extent-parent extent parent
+ This function sets the parent of EXTENT to PARENT. If PARENT is
+ `nil', the extent is set to have no parent.
- - Function: check-valid-instantiator instantiator specifier-type
- This function signals an error if INSTANTIATOR is invalid for
- SPECIFIER-TYPE.
+ - Function: extent-parent extent
+ This function return the parents (if any) of EXTENT, or `nil'.
- - Function: check-valid-inst-list inst-list type
- This function signals an error if INST-LIST is invalid for
- specifier type TYPE.
+ - Function: extent-children extent
+ This function returns a list of the children (if any) of EXTENT.
+ The children of an extent are all those extents whose parent is
+ that extent. This function does not recursively trace children of
+ children.
- - Function: check-valid-spec-list spec-list type
- This function signals an error if SPEC-LIST is invalid for
- specifier type TYPE.
+ - Function: extent-descendants extent
+ This function returns a list of all descendants of EXTENT,
+ including EXTENT. This recursively applies `extent-children' to
+ any children of EXTENT, until no more children can be found.
\1f
-File: lispref.info, Node: Other Specification Functions, Prev: Specifier Validation Functions, Up: Specifiers
-
-Other Functions for Working with Specifications in a Specifier
-==============================================================
-
- - Function: copy-specifier specifier &optional dest locale tag-set
- exact-p how-to-add
- This function copies SPECIFIER to DEST, or creates a new one if
- DEST is `nil'.
-
- If DEST is `nil' or omitted, a new specifier will be created and
- the specifications copied into it. Otherwise, the specifications
- will be copied into the existing specifier in DEST.
-
- If LOCALE is `nil' or the symbol `all', all specifications will be
- copied. If LOCALE is a particular locale, the specification for
- that particular locale will be copied. If LOCALE is a locale
- type, the specifications for all locales of that type will be
- copied. LOCALE can also be a list of locales, locale types,
- and/or `all'; this is equivalent to calling `copy-specifier' for
- each of the elements of the list. See `specifier-spec-list' for
- more information about LOCALE.
-
- Only instantiators where TAG-SET (a list of zero or more tags) is
- a subset of (or possibly equal to) the instantiator's tag set are
- copied. (The default value of `nil' is a subset of all tag sets,
- so in this case no instantiators will be screened out.) If EXACT-P
- is non-`nil', however, TAG-SET must be equal to an instantiator's
- tag set for the instantiator to be copied.
-
- Optional argument HOW-TO-ADD specifies what to do with existing
- specifications in DEST. If nil, then whichever locales or locale
- types are copied will first be completely erased in DEST.
- Otherwise, it is the same as in `add-spec-to-specifier'.
-
- - Function: remove-specifier specifier &optional locale tag-set exact-p
- This function removes specification(s) for SPECIFIER.
-
- If LOCALE is a particular locale (a buffer, window, frame, device,
- or the symbol `global'), the specification for that locale will be
- removed.
-
- If instead, LOCALE is a locale type (i.e. a symbol `buffer',
- `window', `frame', or `device'), the specifications for all
- locales of that type will be removed.
-
- If LOCALE is `nil' or the symbol `all', all specifications will be
- removed.
-
- LOCALE can also be a list of locales, locale types, and/or `all';
- this is equivalent to calling `remove-specifier' for each of the
- elements in the list.
-
- Only instantiators where TAG-SET (a list of zero or more tags) is
- a subset of (or possibly equal to) the instantiator's tag set are
- removed. (The default value of `nil' is a subset of all tag sets,
- so in this case no instantiators will be screened out.) If EXACT-P
- is non-`nil', however, TAG-SET must be equal to an instantiator's
- tag set for the instantiator to be removed.
-
- - Function: map-specifier specifier func &optional locale maparg
- This function applies FUNC to the specification(s) for LOCALE in
- SPECIFIER.
-
- If LOCALE is a locale, FUNC will be called for that locale. If
- LOCALE is a locale type, FUNC will be mapped over all locales of
- that type. If LOCALE is `nil' or the symbol `all', FUNC will be
- mapped over all locales in SPECIFIER.
-
- FUNC is called with four arguments: the SPECIFIER, the locale
- being mapped over, the inst-list for that locale, and the optional
- MAPARG. If any invocation of FUNC returns non-`nil', the mapping
- will stop and the returned value becomes the value returned from
- `map-specifier'. Otherwise, `map-specifier' returns `nil'.
-
- - Function: specifier-locale-type-from-locale locale
- Given a specifier LOCALE, this function returns its type.
+File: lispref.info, Node: Duplicable Extents, Next: Extents and Events, Prev: Extent Parents, Up: Extents
+
+Duplicable Extents
+==================
+
+ If an extent has the `duplicable' property, it will be copied into
+strings, so that kill, yank, and undo commands will restore or copy it.
+
+ Specifically:
+
+ * When a string is created using `buffer-substring' or
+ `buffer-string', any duplicable extents in the region corresponding
+ to the string will be copied into the string (*note Buffer
+ Contents::). When the string is inserted into a buffer using
+ `insert', `insert-before-markers', `insert-buffer' or
+ `insert-buffer-substring', the extents in the string will be copied
+ back into the buffer (*note Insertion::). The extents in a string
+ can, of course, be retrieved explicitly using the standard extent
+ primitives over the string.
+
+ * Similarly, when text is copied or cut into the kill ring, any
+ duplicable extents will be remembered and reinserted later when
+ the text is pasted back into a buffer.
+
+ * When `concat' is called on strings, the extents in the strings are
+ copied into the resulting string.
+
+ * When `substring' is called on a string, the relevant extents are
+ copied into the resulting string.
+
+ * When a duplicable extent is detached by `detach-extent' or string
+ deletion, or inserted by `insert-extent' or string insertion, the
+ action is recorded by the undo mechanism so that it can be undone
+ later. Note that if an extent gets detached and then a later undo
+ causes the extent to get reinserted, the new extent will not be
+ `eq' to the original extent.
+
+ * Extent motion, face changes, and attachment via `make-extent' are
+ not recorded by the undo mechanism. This means that extent changes
+ which are to be undo-able must be performed by character editing,
+ or by insertion and detachment of duplicable extents.
+
+ * A duplicable extent's `copy-function' property, if non-`nil',
+ should be a function, and will be run when a duplicable extent is
+ about to be copied from a buffer to a string (or the kill ring).
+ It is called with three arguments: the extent and the buffer
+ positions within it which are being copied. If this function
+ returns `nil', then the extent will not be copied; otherwise it
+ will.
+
+ * A duplicable extent's `paste-function' property, if non-`nil',
+ should be a function, and will be run when a duplicable extent is
+ about to be copied from a string (or the kill ring) into a buffer.
+ It is called with three arguments: the original extent and the
+ buffer positions which the copied extent will occupy. (This hook
+ is run after the corresponding text has already been inserted into
+ the buffer.) Note that the extent argument may be detached when
+ this function is run. If this function returns `nil', no extent
+ will be inserted. Otherwise, there will be an extent covering the
+ range in question.
+
+ Note: if the extent to be copied is already attached to the buffer
+ and overlaps the new range, the extent will simply be extended and
+ the `paste-function' will not be called.
\1f
-File: lispref.info, Node: Faces and Window-System Objects, Next: Glyphs, Prev: Specifiers, Up: Top
+File: lispref.info, Node: Extents and Events, Next: Atomic Extents, Prev: Duplicable Extents, Up: Extents
+
+Interaction of Extents with Keyboard and Mouse Events
+=====================================================
+
+ If an extent has the `mouse-face' property set, it will be
+highlighted when the mouse passes over it. Highlighting is accomplished
+by merging the extent's face with the face or faces specified by the
+`mouse-face' property. The effect is as if a pseudo-extent with the
+`mouse-face' face were inserted after the extent in the display order
+(*note Extent Endpoints::, display order).
+
+ - Variable: mouse-highlight-priority
+ This variable holds the priority to use when merging in the
+ highlighting pseudo-extent. The default is 1000. This is
+ purposely set very high so that the highlighting pseudo-extent
+ shows up even if there are other extents with various priorities
+ at the same location.
+
+ You can also explicitly cause an extent to be highlighted. Only one
+extent at a time can be highlighted in this fashion, and any other
+highlighted extent will be de-highlighted.
+
+ - Function: highlight-extent extent &optional highlight-p
+ This function highlights (if HIGHLIGHT-P is non-`nil') or
+ de-highlights (if HIGHLIGHT-P is `nil') EXTENT, if EXTENT has the
+ `mouse-face' property. (Nothing happens if EXTENT does not have
+ the `mouse-face' property.)
+
+ - Function: force-highlight-extent extent &optional highlight-p
+ This function is similar to `highlight-extent' but highlights or
+ de-highlights the extent regardless of whether it has the
+ `mouse-face' property.
+
+ If an extent has a `keymap' property, this keymap will be consulted
+for mouse clicks on the extent and keypresses made while `point' is
+within the extent. The behavior of mouse clicks and keystrokes not
+defined in the keymap is as normal for the buffer.
-Faces and Window-System Objects
-*******************************
+\1f
+File: lispref.info, Node: Atomic Extents, Prev: Extents and Events, Up: Extents
-* Menu:
+Atomic Extents
+==============
+
+ If the Lisp file `atomic-extents' is loaded, then the atomic extent
+facility is available. An "atomic extent" is an extent for which
+`point' cannot be positioned anywhere within it. This ensures that
+when selecting text, either all or none of the extent is selected.
-* Faces:: Controlling the way text looks.
-* Fonts:: Controlling the typeface of text.
-* Colors:: Controlling the color of text and pixmaps.
+ To make an extent atomic, set its `atomic' property.
\1f
-File: lispref.info, Node: Faces, Next: Fonts, Up: Faces and Window-System Objects
-
-Faces
-=====
-
- A "face" is a named collection of graphical properties: font,
-foreground color, background color, background pixmap, optional
-underlining, and (on TTY devices) whether the text is to be highlighted,
-dimmed, blinking, or displayed in reverse video. Faces control the
-display of text on the screen. Every face has a name, which is a symbol
-such as `default' or `modeline'.
-
- Each built-in property of a face is controlled using a specifier,
-which allows it to have separate values in particular buffers, frames,
-windows, and devices and to further vary according to device type (X or
-TTY) and device class (color, mono, or grayscale). *Note Specifiers::,
-for more information.
-
- The face named `default' is used for ordinary text. The face named
-`modeline' is used for displaying the modeline. The face named
-`highlight' is used for highlighted extents (*note Extents::). The
-faces named `left-margin' and `right-margin' are used for the left and
-right margin areas, respectively (*note Annotations::). The face named
-`zmacs-region' is used for the highlighted region between point and
-mark.
+File: lispref.info, Node: Specifiers, Next: Faces and Window-System Objects, Prev: Extents, Up: Top
+
+Specifiers
+**********
+
+ A specifier is an object used to keep track of a property whose value
+may vary depending on the particular situation (e.g. particular buffer
+displayed in a particular window) that it is used in. The value of many
+built-in properties, such as the font, foreground, background, and such
+properties of a face and variables such as `modeline-shadow-thickness'
+and `top-toolbar-height', is actually a specifier object. The
+specifier object, in turn, is "instanced" in a particular situation to
+yield the real value of the property in that situation.
+
+ - Function: specifierp object
+ This function returns non-`nil' if OBJECT is a specifier.
* Menu:
-* Merging Faces:: How XEmacs decides which face to use
- for a character.
-* Basic Face Functions:: How to define and examine faces.
-* Face Properties:: How to access and modify a face's properties.
-* Face Convenience Functions:: Convenience functions for accessing
- particular properties of a face.
-* Other Face Display Functions:: Other functions pertaining to how a
- a face appears.
+* Introduction to Specifiers:: Specifiers provide a clean way for
+ display and other properties to vary
+ (under user control) in a wide variety
+ of contexts.
+* Specifiers In-Depth:: Gory details about specifier innards.
+* Specifier Instancing:: Instancing means obtaining the ``value'' of
+ a specifier in a particular context.
+* Specifier Types:: Specifiers come in different flavors.
+* Adding Specifications:: Specifications control a specifier's ``value''
+ by giving conditions under which a
+ particular value is valid.
+* Retrieving Specifications:: Querying a specifier's specifications.
+* Specifier Tag Functions:: Working with specifier tags.
+* Specifier Instancing Functions::
+ Functions to instance a specifier.
+* Specifier Example:: Making all this stuff clearer.
+* Creating Specifiers:: Creating specifiers for your own use.
+* Specifier Validation Functions::
+ Validating the components of a specifier.
+* Other Specification Functions::
+ Other ways of working with specifications.
\1f
-File: lispref.info, Node: Merging Faces, Next: Basic Face Functions, Up: Faces
-
-Merging Faces for Display
--------------------------
-
- Here are all the ways to specify which face to use for display of
-text:
-
- * With defaults. Each frame has a "default face", which is used for
- all text that doesn't somehow specify another face. The face named
- `default' applies to the text area, while the faces `left-margin'
- and `right-margin' apply to the left and right margin areas.
-
- * With text properties. A character may have a `face' property; if
- so, it's displayed with that face. (Text properties are actually
- implemented in terms of extents.) *Note Text Properties::.
-
- * With extents. An extent may have a `face' property, which applies
- to all the text covered by the extent; in addition, if the
- `highlight' property is set, the `highlight' property applies when
- the mouse moves over the extent or if the extent is explicitly
- highlighted. *Note Extents::.
-
- * With annotations. Annotations that are inserted into a buffer can
- specify their own face. (Annotations are actually implemented in
- terms of extents.) *Note Annotations::.
-
- If these various sources together specify more than one face for a
-particular character, XEmacs merges the properties of the various faces
-specified. Extents, text properties, and annotations all use the same
-underlying representation (as extents). When multiple extents cover one
-character, an extent with higher priority overrides those with lower
-priority. *Note Extents::. If no extent covers a particular character,
-the `default' face is used.
-
- If a background pixmap is specified, it determines what will be
-displayed in the background of text characters. If the background
-pixmap is actually a pixmap, with its colors specified, those colors are
-used; if it is a bitmap, the face's foreground and background colors are
-used to color it.
+File: lispref.info, Node: Introduction to Specifiers, Next: Specifiers In-Depth, Up: Specifiers
-\1f
-File: lispref.info, Node: Basic Face Functions, Next: Face Properties, Prev: Merging Faces, Up: Faces
-
-Basic Functions for Working with Faces
---------------------------------------
-
- The properties a face can specify include the font, the foreground
-color, the background color, the background pixmap, the underlining,
-the display table, and (for TTY devices) whether the text is to be
-highlighted, dimmed, blinking, or displayed in reverse video. The face
-can also leave these unspecified, causing them to assume the value of
-the corresponding property of the `default' face.
-
- Here are the basic primitives for working with faces.
-
- - Function: make-face name &optional doc-string temporary
- This function defines and returns a new face named NAME, initially
- with all properties unspecified. It does nothing if there is
- already a face named NAME. Optional argument DOC-STRING specifies
- an explanatory string used for descriptive purposes. If optional
- argument TEMPORARY is non-`nil', the face will automatically
- disappear when there are no more references to it anywhere in text
- or Lisp code (otherwise, the face will continue to exist
- indefinitely even if it is not used).
-
- - Function: face-list &optional temporary
- This function returns a list of the names of all defined faces. If
- TEMPORARY is `nil', only the permanent faces are included. If it
- is `t', only the temporary faces are included. If it is any other
- non-`nil' value both permanent and temporary are included.
-
- - Function: facep object
- This function returns whether the given object is a face.
-
- - Function: copy-face old-face new-name &optional locale how-to-add
- This function defines a new face named NEW-NAME which is a copy of
- the existing face named OLD-FACE. If there is already a face
- named NEW-NAME, then it alters the face to have the same
- properties as OLD-FACE. LOCALE and HOW-TO-ADD let you copy just
- parts of the old face rather than the whole face, and are as in
- `copy-specifier' (*note Specifiers::).
+Introduction to Specifiers
+==========================
+
+ Sometimes you may want the value of a property to vary depending on
+the context the property is used in. A simple example of this in XEmacs
+is buffer-local variables. For example, the variable
+`modeline-format', which controls the format of the modeline, can have
+different values depending on the particular buffer being edited. The
+variable has a default value which most modes will use, but a
+specialized package such as Calendar might change the variable so as to
+tailor the modeline to its own purposes.
+
+ Other properties (such as those that can be changed by the
+`modify-frame-parameters' function, for example the color of the text
+cursor) can have frame-local values, although it might also make sense
+for them to have buffer-local values. In other cases, you might want
+the property to vary depending on the particular window within the
+frame that applies (e.g. the top or bottom window in a split frame), the
+device type that that frame appears on (X or tty), etc. Perhaps you can
+envision some more complicated scenario where you want a particular
+value in a specified buffer, another value in all other buffers
+displayed on a particular frame, another value in all other buffers
+displayed in all other frames on any mono (two-color, e.g. black and
+white only) displays, and a default value in all other circumstances.
+
+ A "specifier" is a generalization of this, allowing a great deal of
+flexibility in controlling exactly what value a property has in which
+circumstances. It is most commonly used for display properties, such as
+an image or the foreground color of a face. As a simple example, you
+can specify that the foreground of the default face be
+
+ * blue for a particular buffer
+
+ * green for all other buffers
+
+ As a more complicated example, you could specify that the foreground
+of the default face be
+
+ * forest green for all buffers displayed in a particular Emacs
+ window, or green if the X server doesn't recognize the color
+ `forest green'
+
+ * blue for all buffers displayed in a particular frame
+
+ * red for all other buffers displayed on a color device
+
+ * white for all other buffers
projects / chise / xemacs-chise.git- / blobdiff