Made a number of revisions suggested by Fredrik Lundh.
Revised the first paragraph so it doesn't sound like it was written
when 7-bit strings were assumed; note that Unicode strings can be used.
diff --git a/Doc/lib/libre.tex b/Doc/lib/libre.tex
index 0c9df2a..37b4ee8 100644
--- a/Doc/lib/libre.tex
+++ b/Doc/lib/libre.tex
@@ -1,21 +1,21 @@
\section{\module{re} ---
- Perl-style regular expression operations.}
+ Regular expression operations}
\declaremodule{standard}{re}
\moduleauthor{Andrew M. Kuchling}{amk1@bigfoot.com}
+\moduleauthor{Fredrik Lundh}{effbot@telia.com}
\sectionauthor{Andrew M. Kuchling}{amk1@bigfoot.com}
-\modulesynopsis{Perl-style regular expression search and match
-operations.}
+\modulesynopsis{Regular expression search and match operations with a
+ Perl-style expression syntax.}
This module provides regular expression matching operations similar to
-those found in Perl. It's 8-bit clean: the strings being processed
-may contain both null bytes and characters whose high bit is set. Regular
-expression pattern strings may not contain null bytes, but can specify
-the null byte using the \code{\e\var{number}} notation.
-Characters with the high bit set may be included. The \module{re}
-module is always available.
+those found in Perl. Regular expression pattern strings may not
+contain null bytes, but can specify the null byte using the
+\code{\e\var{number}} notation. Both patterns and strings to be
+searched can be Unicode strings as well as 8-bit strings. The
+\module{re} module is always available.
Regular expressions use the backslash character (\character{\e}) to
indicate special forms or to allow special characters to be used
@@ -34,6 +34,15 @@
Usually patterns will be expressed in Python code using this raw
string notation.
+\strong{Implementation note:}
+The \module{re}\refstmodindex{pre} module has two distinct
+implementations: \module{sre} is the default implementation and
+includes Unicode support, but may run into stack limitations for some
+patterns. Though this will be fixed for a future release of Python,
+the older implementation (without Unicode support) is still available
+as the \module{pre}\refstmodindex{pre} module.
+
+
\subsection{Regular Expression Syntax \label{re-syntax}}
A regular expression (or RE) specifies a set of strings that matches
@@ -155,9 +164,16 @@
will match any character except \character{5}.
\item[\character{|}]\code{A|B}, where A and B can be arbitrary REs,
-creates a regular expression that will match either A or B. This can
-be used inside groups (see below) as well. To match a literal \character{|},
-use \regexp{\e|}, or enclose it inside a character class, as in \regexp{[|]}.
+creates a regular expression that will match either A or B. An
+arbitrary number of REs can be separated by the \character{|} in this
+way. This can be used inside groups (see below) as well. REs
+separated by \character{|} are tried from left to right, and the first
+one that allows the complete pattern to match is considered the
+accepted branch. This means that if \code{A} matches, \code{B} will
+never be tested, even if it would produce a longer overall match. In
+other words, the \character{|} operator is never greedy. To match a
+literal \character{|}, use \regexp{\e|}, or enclose it inside a
+character class, as in \regexp{[|]}.
\item[\code{(...)}] Matches whatever regular expression is inside the
parentheses, and indicates the start and end of a group; the contents
@@ -184,6 +200,11 @@
include the flags as part of the regular expression, instead of
passing a \var{flag} argument to the \function{compile()} function.
+Note that the \regexp{(?x)} flag changes how the expression is parsed.
+It should be used first in the expression string, or after one or more
+whitespace characters. If there are non-whitespace characters before
+the flag, the results are undefined.
+
\item[\code{(?:...)}] A non-grouping version of regular parentheses.
Matches whatever regular expression is inside the parentheses, but the
substring matched by the