(Regexp Example): Update description of how Emacs currently recognizes

the end of a sentence.
(Standard Regexps): Update definition of the variable `sentence-end'.
Add definition of the function `sentence-end'.

1 files changed, 24 insertions, 22 deletions

diff --git a/lispref/searching.texi b/lispref/searching.texi
index 93a152fbbe1..ee6cb06b1e1 100644
--- a/lispref/searching.texi
+++ b/lispref/searching.texi
@@ -1,6 +1,6 @@
 @c -*-texinfo-*-
 @c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999
+@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1998, 1999, 2004
 @c   Free Software Foundation, Inc.
 @c See the file elisp.texi for copying conditions.
 @setfilename ../info/searching
@@ -694,9 +694,9 @@ an @code{invalid-regexp} error is signaled.
 
   Here is a complicated regexp which was formerly used by Emacs to
 recognize the end of a sentence together with any whitespace that
-follows.  It was used as the variable @code{sentence-end}.  (Its value
-nowadays contains alternatives for @samp{.}, @samp{?} and @samp{!} in
-other character sets.)
+follows.  (Nowadays Emacs uses a similar but more complex default
+regexp constructed by the function @code{sentence-end}.
+@xref{Standard Regexps}.)
 
   First, we show the regexp as a string in Lisp syntax to distinguish
 spaces from tab characters.  The string constant begins and ends with a
@@ -730,9 +730,9 @@ deciphered as follows:
 The first part of the pattern is a character alternative that matches
 any one of three characters: period, question mark, and exclamation
 mark.  The match must begin with one of these three characters.  (This
-is the one point where the new value of @code{sentence-end} differs
-from the old.  The new value also lists sentence ending
-non-@acronym{ASCII} characters.)
+is one point where the new default regexp used by Emacs differs from
+the old.  The new value also allows some non-@acronym{ASCII}
+characters that end a sentence without any following whitespace.)
 
 @item []\"')@}]*
 The second part of the pattern matches any closing braces and quotation
@@ -1698,23 +1698,25 @@ whitespace or starting with a form feed (after its left margin).
 @end defvar
 
 @defvar sentence-end
-This is the regular expression describing the end of a sentence.  (All
-paragraph boundaries also end sentences, regardless.)  The (slightly
-simplified) default value is:
-
-@example
-"[.?!][]\"')@}]*\\($\\| $\\|\t\\|@ @ \\)[ \t\n]*"
-@end example
-
-This means a period, question mark or exclamation mark (the actual
-default value also lists their alternatives in other character sets),
-followed optionally by closing parenthetical characters, followed by
-tabs, spaces or new lines.
-
-For a detailed explanation of this regular expression, see @ref{Regexp
-Example}.
+If non-@code{nil}, the value should be a regular expression describing
+the end of a sentence, including the whitespace following the
+sentence.  (All paragraph boundaries also end sentences, regardless.)
+
+If the value is @code{nil}, the default, then the function
+@code{sentence-end} has to construct the regexp.  That is why you
+should always call the function @code{sentence-end} to obtain the
+regexp to be used to recognize the end of a sentence.
 @end defvar
 
+@defun sentence-end
+This function returns the value of the variable @code{sentence-end},
+if non-@code{nil}.  Otherwise it returns a default value based on the
+values of the variables @code{sentence-end-double-space}
+(@pxref{Definition of sentence-end-double-space}),
+@code{sentence-end-without-period} and
+@code{sentence-end-without-space}.
+@end defun
+
 @ignore
    arch-tag: c2573ca2-18aa-4839-93b8-924043ef831f
 @end ignore