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Copy edits for the regexp sections in the manuals

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* doc/lispref/searching.texi (Regexp Backslash):
* doc/emacs/search.texi (Regexps, Regexp Backslash): Copy edits
from Jay Bingham (bug#41970).
This commit is contained in:
Lars Ingebrigtsen 2022-05-09 13:38:40 +02:00
parent e195ac3df0
commit 60a15fae02
2 changed files with 44 additions and 44 deletions
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56
doc/emacs/search.texi
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@ -1027,24 +1027,9 @@ 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 @kbd{\@{@var{n}\@}}
is a postfix operator specifying @var{n} repetitions---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 @kbd{\@{@var{n},@var{m}\@}}
is a postfix operator specifying between @var{n} and @var{m}
repetitions---that is, the preceding regular expression must match at
least @var{n} times, but no more than @var{m} times. If @var{m} is
omitted, then there is no upper limit, but the preceding regular
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 @kbd{[ @dots{} ]}
is a @dfn{character set}, beginning with @samp{[} and terminated by
@samp{]}.
is a @dfn{a set of alternative characters}, beginning with @samp{[}
and terminated by @samp{]}.
In the simplest case, the characters between the two brackets are what
this set can match. Thus, @samp{[ad]} matches either one @samp{a} or
@ -1132,12 +1117,12 @@ to depend on this behavior; it is better to quote the special character anyway,
regardless of where it appears.
As a @samp{\} is not special inside a character alternative, it can
never remove the special meaning of @samp{-} or @samp{]}. So you
should not quote these characters when they have no special meaning
either. This would not clarify anything, since backslashes can
legitimately precede these characters where they @emph{have} special
meaning, as in @samp{[^\]} (@code{"[^\\]"} for Lisp string syntax),
which matches any single character except a backslash.
never remove the special meaning of @samp{-}, @samp{^} or @samp{]}.
So you should not quote these characters when they have no special
meaning either. This would not clarify anything, since backslashes
can legitimately precede these characters where they @emph{have}
special meaning, as in @samp{[^\]} (@code{"[^\\]"} for Lisp string
syntax), which matches any single character except a backslash.
@node Regexp Backslash
@section Backslash in Regular Expressions
@ -1202,11 +1187,11 @@ matches the same text that matched the @var{d}th occurrence of a
@samp{\( @dots{} \)} construct. This is called a @dfn{back
reference}.
After the end of a @samp{\( @dots{} \)} construct, the matcher remembers
the beginning and end of the text matched by that construct. Then,
later on in the regular expression, you can use @samp{\} followed by the
digit @var{d} to mean ``match the same text matched the @var{d}th time
by the @samp{\( @dots{} \)} construct''.
After the end of a @samp{\( @dots{} \)} construct, the matcher
remembers the beginning and end of the text matched by that construct.
Then, later on in the regular expression, you can use @samp{\}
followed by the digit @var{d} to mean ``match the same text matched
the @var{d}th @samp{\( @dots{} \)} construct''.
The strings matching the first nine @samp{\( @dots{} \)} constructs
appearing in a regular expression are assigned numbers 1 through 9 in
@ -1223,6 +1208,21 @@ If a particular @samp{\( @dots{} \)} construct matches more than once
(which can easily happen if it is followed by @samp{*}), only the last
match is recorded.
@item @kbd{\@{@var{m}\@}}
is a postfix operator specifying @var{m} repetitions---that is, the
preceding regular expression must match exactly @var{m} times in a
row. For example, @samp{x\@{4\@}} matches the string @samp{xxxx} and
nothing else.
@item @kbd{\@{@var{m},@var{n}\@}}
is a postfix operator specifying between @var{m} and @var{n}
repetitions---that is, the preceding regular expression must match at
least @var{m} times, but no more than @var{n} times. If @var{n} is
omitted, then there is no upper limit, but the preceding regular
expression must match at least @var{m} times.@* @samp{\@{0,1\@}} is
equivalent to @samp{?}. @* @samp{\@{0,\@}} is equivalent to
@samp{*}. @* @samp{\@{1,\@}} is equivalent to @samp{+}.
@item \`
matches the empty string, but only at the beginning of the string or
buffer (or its accessible portion) being matched against.

32
doc/lispref/searching.texi
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@ -549,12 +549,12 @@ can act. It is poor practice to depend on this behavior; quote the
special character anyway, regardless of where it appears.
As a @samp{\} is not special inside a character alternative, it can
never remove the special meaning of @samp{-} or @samp{]}. So you
should not quote these characters when they have no special meaning
either. This would not clarify anything, since backslashes can
legitimately precede these characters where they @emph{have} special
meaning, as in @samp{[^\]} (@code{"[^\\]"} for Lisp string syntax),
which matches any single character except a backslash.
never remove the special meaning of @samp{-}, @samp{^} or @samp{]}.
So you should not quote these characters when they have no special
meaning either. This would not clarify anything, since backslashes
can legitimately precede these characters where they @emph{have}
special meaning, as in @samp{[^\]} (@code{"[^\\]"} for Lisp string
syntax), which matches any single character except a backslash.
In practice, most @samp{]} that occur in regular expressions close a
character alternative and hence are special. However, occasionally a
@ -823,21 +823,21 @@ the characters that stand for them.
matches any character whose syntax is not @var{code}.
@cindex category, regexp search for
@item \c@var{c}
matches any character whose category is @var{c}. Here @var{c} is a
character that represents a category: thus, @samp{c} for Chinese
characters or @samp{g} for Greek characters in the standard category
table. You can see the list of all the currently defined categories
with @kbd{M-x describe-categories @key{RET}}. You can also define
your own categories in addition to the standard ones using the
@item \c@var{code}
matches any character whose category is @var{code}. Here @var{code}
is a character that represents a category: thus, @samp{code} for
Chinese characters or @samp{g} for Greek characters in the standard
category table. You can see the list of all the currently defined
categories with @kbd{M-x describe-categories @key{RET}}. You can also
define your own categories in addition to the standard ones using the
@code{define-category} function (@pxref{Categories}).
@item \C@var{c}
matches any character whose category is not @var{c}.
@item \C@var{code}
matches any character whose category is not @var{code}.
@end table
The following regular expression constructs match the empty string---that is,
they don't use up any characters---but whether they match depends on the
they don't consume any characters---but whether they match depends on the
context. For all, the beginning and end of the accessible portion of
the buffer are treated as if they were the actual beginning and end of
the buffer.