GNU Emacs Lisp Reference Manual
GNU Emacs Lisp Reference Manual
Here is a table of syntax classes, the characters that stand for them, their meanings, and examples of their use.
@ or -)
separate symbols and words from each other. Typically, whitespace
characters have no other syntactic significance, and multiple whitespace
characters are syntactically equivalent to a single one. Space, tab,
newline and formfeed are almost always classified as whitespace.
w) are parts of normal
English words and are typically used in variable and command names in
programs. All upper- and lower-case letters, and the digits, are typically
word constituents.
_) are the extra
characters that are used in variable and command names along with word
constituents. For example, the symbol constituents class is used in
Lisp mode to indicate that certain characters may be part of symbol
names even though they are not part of English words. These characters
are $&*+-_<>. In standard C, the only non-word-constituent
character that is valid in symbols is underscore (_).
.) are those characters that are
used as punctuation in English, or are used in some way in a programming
language to separate symbols from one another. Most programming
language modes, including Emacs Lisp mode, have no characters in this
class since the few characters that are not symbol or word constituents
all have other uses.
The class of open parentheses is designated with (, and that of
close parentheses with ).
In English text, and in C code, the parenthesis pairs are (),
[], and {}. In Emacs Lisp, the delimiters for lists and
vectors (() and []) are classified as parenthesis
characters.
") are used in
many languages, including Lisp and C, to delimit string constants. The
same string quote character appears at the beginning and the end of a
string. Such quoted strings do not nest.
The parsing facilities of Emacs consider a string as a single token. The usual syntactic meanings of the characters in the string are suppressed.
The Lisp modes have two string quote characters: double-quote (")
and vertical bar (|). | 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 (') for character
constants.
English text has no string quote characters because English is not a programming language. Although quotation marks are used in English, we do not want them to turn off the usual syntactic properties of other characters in the quotation.
\) starts an escape
sequence such as is used in C string and character constants. The
character \ belongs to this class in both C and Lisp. (In C, it
is used thus only inside strings, but it turns out to cause no trouble
to treat it this way throughout C code.)
Characters in this class count as part of words if
words-include-escapes is non-nil. See Word Motion.
/) quotes the
following character so that it loses its normal syntactic meaning. This
differs from an escape character in that only the character immediately
following is ever affected.
Characters in this class count as part of words if
words-include-escapes is non-nil. See Word Motion.
This class is used for backslash in TeX mode.
$) are like
string quote characters except that the syntactic properties of the
characters between the delimiters are not suppressed. Only TeX mode
uses a paired delimiter presently---the $ that both enters and
leaves math mode.
') is used
for syntactic operators that are part of an expression if they appear
next to one. These characters in Lisp include the apostrophe, '
(used for quoting), the comma, , (used in macros), and #
(used in the read syntax for certain data types).
< and >, respectively.
English text has no comment characters. In Lisp, the semicolon
(;) starts a comment and a newline or formfeed ends one.
@.