@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990-1995, 1998-1999, 2001-2013 Free Software
+@c Copyright (C) 1990-1995, 1998-1999, 2001-2016 Free Software
@c Foundation, Inc.
@c See the file elisp.texi for copying conditions.
@node Syntax Tables
Usually, this designator character is one that is often assigned that
class; however, its meaning as a designator is unvarying and
independent of what syntax that character currently has. Thus,
-@samp{\} as a designator character always means ``escape character''
+@samp{\} as a designator character always stands for escape character
syntax, regardless of whether the @samp{\} character actually has that
syntax in the current syntax table.
@ifnottex
@node Syntax Class Table
@subsection Table of Syntax Classes
+@cindex syntax class table
Here is a table of syntax classes, the characters that designate
them, their meanings, and examples of their use.
The Lisp modes have two string quote characters: double-quote (@samp{"})
and vertical bar (@samp{|}). @samp{|} is not used in Emacs Lisp, but it
is used in Common Lisp. C also has two string quote characters:
-double-quote for strings, and single-quote (@samp{'}) for character
+double-quote for strings, and apostrophe (@samp{'}) for character
constants.
Human text has no string quote characters. We do not want quotation
comment delimiter, @samp{n} on either character makes it
nestable.
+@cindex comment style
Emacs supports several comment styles simultaneously in any one syntax
table. A comment style is a set of flags @samp{b}, @samp{c}, and
@samp{n}, so there can be up to 8 different comment styles.
@end table
@item
-@samp{p} identifies an additional ``prefix character'' for Lisp syntax.
+@samp{p} identifies an additional prefix character for Lisp syntax.
These characters are treated as whitespace when they appear between
expressions. When they appear within an expression, they are handled
according to their usual syntax classes.
@end defun
@deffn Command modify-syntax-entry char syntax-descriptor &optional table
+@cindex syntax entry, setting
This function sets the syntax entry for @var{char} according to
@var{syntax-descriptor}. @var{char} must be a character, or a cons
cell of the form @code{(@var{min} . @var{max})}; in the latter case,
the current buffer.
@end defun
+@deffn Command describe-syntax &optional buffer
+This command displays the contents of the syntax table of
+@var{buffer} (by default, the current buffer) in a help buffer.
+@end deffn
+
@defmac with-syntax-table table body@dots{}
This macro executes @var{body} using @var{table} as the current syntax
table. It returns the value of the last form in @var{body}, after
@node Motion and Syntax
@section Motion and Syntax
+@cindex moving across syntax classes
+@cindex skipping characters of certain syntax
This section describes functions for moving across characters that
have certain syntax classes.
@node Parsing Expressions
@section Parsing Expressions
+@cindex parsing expressions
+@cindex scanning expressions
This section describes functions for parsing and scanning balanced
expressions. We will refer to such expressions as @dfn{sexps},
following the terminology of Lisp, even though these functions can act
on languages other than Lisp. Basically, a sexp is either a balanced
-parenthetical grouping, a string, or a ``symbol'' (i.e., a sequence
+parenthetical grouping, a string, or a symbol (i.e., a sequence
of characters whose syntax is either word constituent or symbol
constituent). However, characters in the expression prefix syntax
class (@pxref{Syntax Class Table}) are treated as part of the sexp if
A character's syntax controls how it changes the state of the
parser, rather than describing the state itself. For example, a
string delimiter character toggles the parser state between
-``in-string'' and ``in-code'', but the syntax of characters does not
+in-string and in-code, but the syntax of characters does not
directly say whether they are inside a string. For example (note that
15 is the syntax code for generic string delimiters),
@node Motion via Parsing
@subsection Motion Commands Based on Parsing
+@cindex motion based on parsing
This section describes simple point-motion functions that operate
based on parsing expressions.
expected, with nothing except whitespace between them, it returns
@code{t}; otherwise it returns @code{nil}.
-This function cannot tell whether the ``comments'' it traverses are
+This function cannot tell whether the comments it traverses are
embedded within a string. If they look like comments, it treats them
as comments.
@node Position Parse
@subsection Finding the Parse State for a Position
+@cindex parse state for a position
For syntactic analysis, such as in indentation, often the useful
thing is to compute the syntactic state corresponding to a given buffer
@node Control Parsing
@subsection Parameters to Control Parsing
+@cindex parsing, control parameters
@defvar multibyte-syntax-as-symbol
If this variable is non-@code{nil}, @code{scan-sexps} treats all
The behavior of @code{parse-partial-sexp} is also affected by
@code{parse-sexp-lookup-properties} (@pxref{Syntax Properties}).
+@defvar comment-end-can-be-escaped
+If this buffer local variable is non-@code{nil}, a single character
+which usually terminates a comment doesn't do so when that character
+is escaped. This is used in C and C++ Modes, where line comments
+starting with @samp{//} can be continued onto the next line by
+escaping the newline with @samp{\}.
+@end defvar
+
You can use @code{forward-comment} to move forward or backward over
one comment or several comments.
the range @w{@samp{ }} to @samp{~}. You specify the name of a category
when you define it with @code{define-category}.
+@cindex category set
The category table is actually a char-table (@pxref{Char-Tables}).
The element of the category table at index @var{c} is a @dfn{category
set}---a bool-vector---that indicates which categories character @var{c}
Here's an example of defining a new category for characters that have
strong right-to-left directionality (@pxref{Bidirectional Display})
-and using it in a special category table:
+and using it in a special category table. To obtain the information
+about the directionality of characters, the example code uses the
+@samp{bidi-class} Unicode property (@pxref{Character Properties,
+bidi-class}).
@example
(defvar special-category-table-for-bidi
+ ;; Make an empty category-table.
(let ((category-table (make-category-table))
- (uniprop-table (unicode-property-table-internal 'bidi-class)))
+ ;; Create a char-table which gives the 'bidi-class' Unicode
+ ;; property for each character.
+ (uniprop-table (unicode-property-table-internal 'bidi-class)))
(define-category ?R "Characters of bidi-class R, AL, or RLO"
category-table)
+ ;; Modify the category entry of each character whose 'bidi-class'
+ ;; Unicode property is R, AL, or RLO -- these have a
+ ;; right-to-left directionality.
(map-char-table
#'(lambda (key val)
- (if (memq val '(R AL RLO))
- (modify-category-entry key ?R category-table)))
+ (if (memq val '(R AL RLO))
+ (modify-category-entry key ?R category-table)))
uniprop-table)
category-table))
@end example