@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998 Free Software Foundation, Inc.
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2002, 2003,
+@c 2004, 2005, 2006 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@setfilename ../info/sequences
-@node Sequences Arrays Vectors, Symbols, Lists, Top
+@node Sequences Arrays Vectors, Hash Tables, Lists, Top
@chapter Sequences, Arrays, and Vectors
@cindex sequence
sequence.
@defun sequencep object
-Returns @code{t} if @var{object} is a list, vector, or
-string, @code{nil} otherwise.
+Returns @code{t} if @var{object} is a list, vector, string,
+bool-vector, or char-table, @code{nil} otherwise.
@end defun
@defun length sequence
@cindex list length
@cindex vector length
@cindex sequence length
+@cindex char-table length
This function returns the number of elements in @var{sequence}. If
-@var{sequence} is a cons cell that is not a list (because the final
-@sc{cdr} is not @code{nil}), a @code{wrong-type-argument} error is
-signaled.
+@var{sequence} is a dotted list, a @code{wrong-type-argument} error is
+signaled. Circular lists may cause an infinite loop. For a
+char-table, the value returned is always one more than the maximum
+Emacs character code.
-@xref{List Elements}, for the related function @code{safe-list}.
+@xref{Definition of safe-length}, for the related function @code{safe-length}.
@example
@group
@end example
@end defun
+@defun string-bytes string
+@cindex string, number of bytes
+This function returns the number of bytes in @var{string}.
+If @var{string} is a multibyte string, this is greater than
+@code{(length @var{string})}.
+@end defun
+
@defun elt sequence index
@cindex elements of sequences
This function returns the element of @var{sequence} indexed by
-@var{index}. Legitimate values of @var{index} are integers ranging from
-0 up to one less than the length of @var{sequence}. If @var{sequence}
-is a list, then out-of-range values of @var{index} return @code{nil};
-otherwise, they trigger an @code{args-out-of-range} error.
+@var{index}. Legitimate values of @var{index} are integers ranging
+from 0 up to one less than the length of @var{sequence}. If
+@var{sequence} is a list, out-of-range values behave as for
+@code{nth}. @xref{Definition of nth}. Otherwise, out-of-range values
+trigger an @code{args-out-of-range} error.
@example
@group
@end group
@group
(elt [1 2 3 4] 4)
- @error{}Args out of range: [1 2 3 4], 4
+ @error{} Args out of range: [1 2 3 4], 4
@end group
@group
(elt [1 2 3 4] -1)
- @error{}Args out of range: [1 2 3 4], -1
+ @error{} Args out of range: [1 2 3 4], -1
@end group
@end example
This function generalizes @code{aref} (@pxref{Array Functions}) and
-@code{nth} (@pxref{List Elements}).
+@code{nth} (@pxref{Definition of nth}).
@end defun
@defun copy-sequence sequence
list. However, the actual values of the properties are shared.
@xref{Text Properties}.
+This function does not work for dotted lists. Trying to copy a
+circular list may cause an infinite loop.
+
See also @code{append} in @ref{Building Lists}, @code{concat} in
-@ref{Creating Strings}, and @code{vconcat} in @ref{Vectors}, for others
-ways to copy sequences.
+@ref{Creating Strings}, and @code{vconcat} in @ref{Vector Functions},
+for other ways to copy sequences.
@example
@group
requires access time that is proportional to the position of the element
in the list.
- Emacs defines four types of array, both of which are one-dimensional:
-@dfn{strings}, @dfn{vectors}, @dfn{bool-vectors} and @dfn{char-tables}.
-A vector is a general array; its elements can be any Lisp objects. A
-string is a specialized array; its elements must be characters (i.e.,
-integers between 0 and 255). Each type of array has its own read
-syntax. @xref{String Type}, and @ref{Vector Type}.
+ Emacs defines four types of array, all one-dimensional: @dfn{strings},
+@dfn{vectors}, @dfn{bool-vectors} and @dfn{char-tables}. A vector is a
+general array; its elements can be any Lisp objects. A string is a
+specialized array; its elements must be characters. Each type of array
+has its own read syntax.
+@xref{String Type}, and @ref{Vector Type}.
All four kinds of array share these characteristics:
change the length of an existing array.
@item
-The array is a constant, for evaluation---in other words, it evaluates
-to itself.
+For purposes of evaluation, the array is a constant---in other words,
+it evaluates to itself.
@item
The elements of an array may be referenced or changed with the functions
@end group
@group
(aref "abcdefg" 1)
- @result{} 98 ; @r{@samp{b} is @sc{ASCII} code 98.}
+ @result{} 98 ; @r{@samp{b} is @acronym{ASCII} code 98.}
@end group
@end example
@end example
If @var{array} is a string and @var{object} is not a character, a
-@code{wrong-type-argument} error results. If @var{array} is a string
-and @var{object} is character, but @var{object} does not use the same
-number of bytes as the character currently stored in @code{(aref
-@var{object} @var{index})}, that is also an error. @xref{Chars and
-Bytes}.
+@code{wrong-type-argument} error results. The function converts a
+unibyte string to multibyte if necessary to insert a character.
@end defun
@defun fillarray array object
@defun vconcat &rest sequences
@cindex copying vectors
This function returns a new vector containing all the elements of the
-@var{sequences}. The arguments @var{sequences} may be any kind of
-arrays, including lists, vectors, or strings. If no @var{sequences} are
-given, an empty vector is returned.
+@var{sequences}. The arguments @var{sequences} may be true lists,
+vectors, strings or bool-vectors. If no @var{sequences} are given, an
+empty vector is returned.
The value is a newly constructed vector that is not @code{eq} to any
existing vector.
arguments. This is a special feature to make it easy to access the entire
contents of a byte-code function object. @xref{Byte-Code Objects}.
-The @code{vconcat} function also allows integers as arguments. It
-converts them to strings of digits, making up the decimal print
-representation of the integer, and then uses the strings instead of the
-original integers. @strong{Don't use this feature; we plan to eliminate
-it. If you already use this feature, change your programs now!} The
-proper way to convert an integer to a decimal number in this way is with
-@code{format} (@pxref{Formatting Strings}) or @code{number-to-string}
-(@pxref{String Conversion}).
+In Emacs versions before 21, the @code{vconcat} function allowed
+integers as arguments, converting them to strings of digits, but that
+feature has been eliminated. The proper way to convert an integer to
+a decimal number in this way is with @code{format} (@pxref{Formatting
+Strings}) or @code{number-to-string} (@pxref{String Conversion}).
For other concatenation functions, see @code{mapconcat} in @ref{Mapping
Functions}, @code{concat} in @ref{Creating Strings}, and @code{append}
in @ref{Building Lists}.
@end defun
- The @code{append} function provides a way to convert a vector into a
-list with the same elements (@pxref{Building Lists}):
+ The @code{append} function also provides a way to convert a vector into a
+list with the same elements:
@example
@group
@node Char-Tables
@section Char-Tables
@cindex char-tables
+@cindex extra slots of char-table
A char-table is much like a vector, except that it is indexed by
character codes. Any valid character code, without modifiers, can be
used as an index in a char-table. You can access a char-table's
-elements with @code{aref} and @code{aset}, as with any array.
-Char-tables are constants when evaluated.
+elements with @code{aref} and @code{aset}, as with any array. In
+addition, a char-table can have @dfn{extra slots} to hold additional
+data not associated with particular character codes. Char-tables are
+constants when evaluated.
-@cindex extra slots of char-table
@cindex subtype of char-table
- Each char-table has a @dfn{subtype} which is a symbol. In order to be
-a valid subtype, a symbol must have a @code{char-table-extra-slots}
-property which is an integer between 0 and 10. This integer specifies
-the number of @dfn{extra slots} in the char-table.
+ Each char-table has a @dfn{subtype} which is a symbol. The subtype
+has two purposes: to distinguish char-tables meant for different uses,
+and to control the number of extra slots. For example, display tables
+are char-tables with @code{display-table} as the subtype, and syntax
+tables are char-tables with @code{syntax-table} as the subtype. A valid
+subtype must have a @code{char-table-extra-slots} property which is an
+integer between 0 and 10. This integer specifies the number of
+@dfn{extra slots} in the char-table.
@cindex parent of char-table
- A char-table can have a @dfn{parent}. which is another char-table. If
+ A char-table can have a @dfn{parent}, which is another char-table. If
it does, then whenever the char-table specifies @code{nil} for a
particular character @var{c}, it inherits the value specified in the
parent. In other words, @code{(aref @var{char-table} @var{c})} returns
@code{(aref @var{char-table} @var{c})} returns the default value
whenever the char-table does not specify any other non-@code{nil} value.
-@tindex make-char-table
@defun make-char-table subtype &optional init
Return a newly created char-table, with subtype @var{subtype}. Each
element is initialized to @var{init}, which defaults to @code{nil}. You
all char-tables have room for any valid character code as an index.
@end defun
-@tindex char-table-p
@defun char-table-p object
This function returns @code{t} if @var{object} is a char-table,
otherwise @code{nil}.
@end defun
-@tindex char-table-subtype
@defun char-table-subtype char-table
This function returns the subtype symbol of @var{char-table}.
@end defun
-@tindex set-char-table-default
-@defun set-char-table-default char-table new-default
-This function sets the default value of @var{char-table} to
-@var{new-default}.
+@defun set-char-table-default char-table char new-default
+This function sets the default value of generic character @var{char}
+in @var{char-table} to @var{new-default}.
-There is no special function to access the default value of a char-table.
-To do that, use @code{(char-table-range @var{char-table} nil)}.
+There is no special function to access default values in a char-table.
+To do that, use @code{char-table-range} (see below).
@end defun
-@tindex char-table-parent
@defun char-table-parent char-table
This function returns the parent of @var{char-table}. The parent is
always either @code{nil} or another char-table.
@end defun
-@tindex set-char-table-parent
@defun set-char-table-parent char-table new-parent
This function sets the parent of @var{char-table} to @var{new-parent}.
@end defun
-@tindex char-table-extra-slot
@defun char-table-extra-slot char-table n
This function returns the contents of extra slot @var{n} of
@var{char-table}. The number of extra slots in a char-table is
determined by its subtype.
@end defun
-@tindex set-char-table-extra-slot
@defun set-char-table-extra-slot char-table n value
This function stores @var{value} in extra slot @var{n} of
@var{char-table}.
A char-table can specify an element value for a single character code;
it can also specify a value for an entire character set.
-@tindex char-table-range
@defun char-table-range char-table range
This returns the value specified in @var{char-table} for a range of
-characters @var{range}. Here @var{range} may be
+characters @var{range}. Here are the possibilities for @var{range}:
@table @asis
@item @code{nil}
Refers to the default value.
@item @var{char}
-Refers to the element for character @var{char}.
+Refers to the element for character @var{char}
+(supposing @var{char} is a valid character code).
@item @var{charset}
Refers to the value specified for the whole character set
@var{charset} (@pxref{Character Sets}).
+
+@item @var{generic-char}
+A generic character stands for a character set, or a row of a
+character set; specifying the generic character as argument is
+equivalent to specifying the character set name. @xref{Splitting
+Characters}, for a description of generic characters.
@end table
@end defun
-@tindex set-char-table-range
@defun set-char-table-range char-table range value
-This function set the value in @var{char-table} for a range of
-characters @var{range}. Here @var{range} may be
+This function sets the value in @var{char-table} for a range of
+characters @var{range}. Here are the possibilities for @var{range}:
@table @asis
@item @code{nil}
Refers to the whole range of character codes.
@item @var{char}
-Refers to the element for character @var{char}.
+Refers to the element for character @var{char}
+(supposing @var{char} is a valid character code).
@item @var{charset}
Refers to the value specified for the whole character set
@var{charset} (@pxref{Character Sets}).
+
+@item @var{generic-char}
+A generic character stands for a character set; specifying the generic
+character as argument is equivalent to specifying the character set
+name. @xref{Splitting Characters}, for a description of generic characters.
@end table
@end defun
-@tindex map-char-table
@defun map-char-table function char-table
This function calls @var{function} for each element of @var{char-table}.
@var{function} is called with two arguments, a key and a value. The key
-is a possible @var{range} argument for @code{char-table-range}, and the
-value is @code{(char-table-range @var{char-table} @var{key})}. Invalid
-character codes are never used as @var{key}.
+is a possible @var{range} argument for @code{char-table-range}---either
+a valid character or a generic character---and the value is
+@code{(char-table-range @var{char-table} @var{key})}.
Overall, the key-value pairs passed to @var{function} describe all the
values stored in @var{char-table}.
+
+The return value is always @code{nil}; to make this function useful,
+@var{function} should have side effects. For example,
+here is how to examine each element of the syntax table:
+
+@example
+(let (accumulator)
+ (map-char-table
+ #'(lambda (key value)
+ (setq accumulator
+ (cons (list key value) accumulator)))
+ (syntax-table))
+ accumulator)
+@result{}
+((475008 nil) (474880 nil) (474752 nil) (474624 nil)
+ ... (5 (3)) (4 (3)) (3 (3)) (2 (3)) (1 (3)) (0 (3)))
+@end example
@end defun
@node Bool-Vectors
from that, you manipulate them with same functions used for other kinds
of arrays.
-@tindex make-bool-vector
@defun make-bool-vector length initial
-Return a new book-vector of @var{length} elements,
+Return a new bool-vector of @var{length} elements,
each one initialized to @var{initial}.
@end defun
and @code{nil} otherwise.
@end defun
+ Here is an example of creating, examining, and updating a
+bool-vector. Note that the printed form represents up to 8 boolean
+values as a single character.
+
+@example
+(setq bv (make-bool-vector 5 t))
+ @result{} #&5"^_"
+(aref bv 1)
+ @result{} t
+(aset bv 3 nil)
+ @result{} nil
+bv
+ @result{} #&5"^W"
+@end example
+
+@noindent
+These results make sense because the binary codes for control-_ and
+control-W are 11111 and 10111, respectively.
+
+@ignore
+ arch-tag: fcf1084a-cd29-4adc-9f16-68586935b386
+@end ignore