diff options
| -rw-r--r-- | lispref/searching.texi | 41 | ||||
| -rw-r--r-- | src/ChangeLog | 7 |
2 files changed, 43 insertions, 5 deletions
diff --git a/lispref/searching.texi b/lispref/searching.texi index b38b6d9577..0b54fcd2fe 100644 --- a/lispref/searching.texi +++ b/lispref/searching.texi @@ -477,6 +477,25 @@ Full backtracking capability exists to handle multiple uses of @samp{\|}, if you use the POSIX regular expression functions (@pxref{POSIX Regexps}). +@item \@{@var{m}\@} +is a postfix operator that repeats the previous pattern exactly @var{m} +times. Thus, @samp{x\@{5\@}} matches the string @samp{xxxxx} +and nothing else. @samp{c[ad]\@{3\@}r} matches string such as +@samp{caaar}, @samp{cdddr}, @samp{cadar}, and so on. + +@item \@{@var{m},@var{n}\@} +is more general postfix operator that specifies repetition with a +minimum of @var{m} repeats and a maximum of @var{n} repeats. If @var{m} +is omitted, the minimum is 0; if @var{n} is omitted, there is no +maximum. + +For example, @samp{c[ad]\@{1,2\@}r} matches the strings @samp{car}, +@samp{cdr}, @samp{caar}, @samp{cadr}, @samp{cdar}, and @samp{cddr}, and +nothing else.@* +@samp{\@{0,1\@}} or @samp{\@{,1\@}} is equivalent to @samp{?}. @* +@samp{\@{0,\@}} or @samp{\@{,\@}} is equivalent to @samp{*}. @* +@samp{\@{1,\@}} is equivalent to @samp{+}. + @item \( @dots{} \) @cindex @samp{(} in regexp @cindex @samp{)} in regexp @@ -496,14 +515,26 @@ To enclose a complicated expression for the postfix operators @samp{*}, number (zero or more) of @samp{na} strings. @item -To record a matched substring for future reference. +To record a matched substring for future reference with +@samp{\@var{digit}} (see below). @end enumerate This last application is not a consequence of the idea of a -parenthetical grouping; it is a separate feature that happens to be -assigned as a second meaning to the same @samp{\( @dots{} \)} construct -because there is no conflict in practice between the two meanings. -Here is an explanation of this feature: +parenthetical grouping; it is a separate feature that was assigned as a +second meaning to the same @samp{\( @dots{} \)} construct because, in +pratice, there was usually no conflict between the two meanings. But +occasionally there is a conflict, and that led to the introduction of +shy groups. + +@item \(?: @dots{} \) +is the @dfn{shy group} construct. A shy group serves the first two +purposes of an ordinary group (controlling the nesting of other +operators), but it does not get a number, so you cannot refer back to +its value with @samp{\@var{digit}}. + +Shy groups are particulary useful for mechanically-constructed regular +expressions because they can be added automatically without altering the +numbering of any ordinary, non-shy groups. @item \@var{digit} matches the same text that matched the @var{digit}th occurrence of a diff --git a/src/ChangeLog b/src/ChangeLog index a5b5ecb6f3..50d9730beb 100644 --- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,3 +1,10 @@ +2000-02-20 Richard M. Stallman <[email protected]> + + * data.c (Fmake_variable_buffer_local): Doc fix. + Init found_for_buffer to 0. + (Fmake_variable_frame_local): If the variable has already + been buffer-local, set the check_frame field. + 2000-02-20 Eli Zaretskii <[email protected]> * msdos.c (IT_write_glyphs): Allocate a larger screen_buf as data |