(Regexps): Convert the main table into @table @asis.

This commit is contained in:
Richard M. Stallman 2003-02-26 09:55:45 +00:00
parent 6a080ff1ea
commit f31431028f

View file

@ -413,14 +413,14 @@ and @samp{o} to get the regular expression @samp{fo}, which matches only
the string @samp{fo}. Still trivial. To do something nontrivial, you
need to use one of the special characters. Here is a list of them.
@table @kbd
@item .@: @r{(Period)}
@table @asis
@item @kbd{.}@: @r{(Period)}
is a special character that matches any single character except a newline.
Using concatenation, we can make regular expressions like @samp{a.b}, which
matches any three-character string that begins with @samp{a} and ends with
@samp{b}.@refill
@item *
@item @kbd{*}
is not a construct by itself; it is a postfix operator that means to
match the preceding regular expression repetitively as many times as
possible. Thus, @samp{o*} matches any number of @samp{o}s (including no
@ -441,18 +441,18 @@ tries to match all three @samp{a}s; but the rest of the pattern is
The next alternative is for @samp{a*} to match only two @samp{a}s.
With this choice, the rest of the regexp matches successfully.@refill
@item +
@item @kbd{+}
is a postfix operator, similar to @samp{*} except that it must match
the preceding expression at least once. So, for example, @samp{ca+r}
matches the strings @samp{car} and @samp{caaaar} but not the string
@samp{cr}, whereas @samp{ca*r} matches all three strings.
@item ?
@item @kbd{?}
is a postfix operator, similar to @samp{*} except that it can match the
preceding expression either once or not at all. For example,
@samp{ca?r} matches @samp{car} or @samp{cr}; nothing else.
@item *?, +?, ??
@item @kbd{*?}, @kbd{+?}, @kbd{??}
@cindex non-greedy regexp matching
are non-greedy variants of the operators above. The normal operators
@samp{*}, @samp{+}, @samp{?} are @dfn{greedy} in that they match as
@ -473,13 +473,13 @@ you search for @samp{a.*?$} against the text @samp{abbab} followed by
a newline, it matches the whole string. Since it @emph{can} match
starting at the first @samp{a}, it does.
@item \@{@var{n}\@}
@item @kbd{\@{@var{n}\@}}
is a postfix operator that specifies repetition @var{n} times---that
is, the preceding regular expression must match exactly @var{n} times
in a row. For example, @samp{x\@{4\@}} matches the string @samp{xxxx}
and nothing else.
@item \@{@var{n},@var{m}\@}
@item @kbd{\@{@var{n},@var{m}\@}}
is a postfix operator that specifies repetition between @var{n} and
@var{m} times---that is, the preceding regular expression must match
at least @var{n} times, but no more than @var{m} times. If @var{m} is
@ -488,7 +488,7 @@ expression must match at least @var{n} times.@* @samp{\@{0,1\@}} is
equivalent to @samp{?}. @* @samp{\@{0,\@}} is equivalent to
@samp{*}. @* @samp{\@{1,\@}} is equivalent to @samp{+}.
@item [ @dots{} ]
@item @kbd{[ @dots{} ]}
is a @dfn{character set}, which begins with @samp{[} and is terminated
by @samp{]}. In the simplest case, the characters between the two
brackets are what this set can match.
@ -523,7 +523,7 @@ ends of the range in upper case, or both in lower case, or both should
be non-letters. The behavior of a mixed-case range such as @samp{A-z}
is somewhat ill-defined, and it may change in future Emacs versions.
@item [^ @dots{} ]
@item @kbd{[^ @dots{} ]}
@samp{[^} begins a @dfn{complemented character set}, which matches any
character except the ones specified. Thus, @samp{[^a-z0-9A-Z]} matches
all characters @emph{except} ASCII letters and digits.
@ -536,17 +536,17 @@ A complemented character set can match a newline, unless newline is
mentioned as one of the characters not to match. This is in contrast to
the handling of regexps in programs such as @code{grep}.
@item ^
@item @kbd{^}
is a special character that matches the empty string, but only at the
beginning of a line in the text being matched. Otherwise it fails to
match anything. Thus, @samp{^foo} matches a @samp{foo} that occurs at
the beginning of a line.
@item $
@item @kbd{$}
is similar to @samp{^} but matches only at the end of a line. Thus,
@samp{x+$} matches a string of one @samp{x} or more at the end of a line.
@item \
@item @kbd{\}
has two functions: it quotes the special characters (including
@samp{\}), and it introduces additional special constructs.