From 4ccef1697aa2e9991fd1494fb037cf52dd77c53d Mon Sep 17 00:00:00 2001
From: Philip Hazel
As well as Perl-style regular expression patterns, some features that appeared @@ -193,18 +194,18 @@ function, listing its arguments and results.
Philip Hazel
-University Computing Service
+Retired from University Computing Service
Cambridge, England.
Putting an actual email address here is a spam magnet. If you want to email me, -use my two initials, followed by the two digits 10, at the domain cam.ac.uk. +use my two names separated by a dot at google.com.
-Last updated: 28 April 2021
+Last updated: 25 August 2021
Copyright © 1997-2021 University of Cambridge.
diff --git a/doc/pcre2.txt b/doc/pcre2.txt
index c6343c6..4837473 100644
--- a/doc/pcre2.txt
+++ b/doc/pcre2.txt
@@ -25,121 +25,122 @@ INTRODUCTION
API is more extensible, and it was simplified by abolishing the sepa-
rate "study" optimizing function; in PCRE2, patterns are automatically
optimized where possible. Since forking from PCRE1, the code has been
- extensively refactored and new features introduced.
+ extensively refactored and new features introduced. The old library is
+ now obsolete and is no longer maintained.
- As well as Perl-style regular expression patterns, some features that
- appeared in Python and the original PCRE before they appeared in Perl
- are available using the Python syntax. There is also some support for
- one or two .NET and Oniguruma syntax items, and there are options for
- requesting some minor changes that give better ECMAScript (aka Java-
+ As well as Perl-style regular expression patterns, some features that
+ appeared in Python and the original PCRE before they appeared in Perl
+ are available using the Python syntax. There is also some support for
+ one or two .NET and Oniguruma syntax items, and there are options for
+ requesting some minor changes that give better ECMAScript (aka Java-
Script) compatibility.
- The source code for PCRE2 can be compiled to support strings of 8-bit,
+ The source code for PCRE2 can be compiled to support strings of 8-bit,
16-bit, or 32-bit code units, which means that up to three separate li-
braries may be installed, one for each code unit size. The size of code
- unit is not related to the bit size of the underlying hardware. In a
- 64-bit environment that also supports 32-bit applications, versions of
+ unit is not related to the bit size of the underlying hardware. In a
+ 64-bit environment that also supports 32-bit applications, versions of
PCRE2 that are compiled in both 64-bit and 32-bit modes may be needed.
- The original work to extend PCRE to 16-bit and 32-bit code units was
+ The original work to extend PCRE to 16-bit and 32-bit code units was
done by Zoltan Herczeg and Christian Persch, respectively. In all three
- cases, strings can be interpreted either as one character per code
+ cases, strings can be interpreted either as one character per code
unit, or as UTF-encoded Unicode, with support for Unicode general cate-
- gory properties. Unicode support is optional at build time (but is the
+ gory properties. Unicode support is optional at build time (but is the
default). However, processing strings as UTF code units must be enabled
explicitly at run time. The version of Unicode in use can be discovered
by running
pcre2test -C
- The three libraries contain identical sets of functions, with names
- ending in _8, _16, or _32, respectively (for example, pcre2_com-
- pile_8()). However, by defining PCRE2_CODE_UNIT_WIDTH to be 8, 16, or
- 32, a program that uses just one code unit width can be written using
+ The three libraries contain identical sets of functions, with names
+ ending in _8, _16, or _32, respectively (for example, pcre2_com-
+ pile_8()). However, by defining PCRE2_CODE_UNIT_WIDTH to be 8, 16, or
+ 32, a program that uses just one code unit width can be written using
generic names such as pcre2_compile(), and the documentation is written
assuming that this is the case.
In addition to the Perl-compatible matching function, PCRE2 contains an
- alternative function that matches the same compiled patterns in a dif-
+ alternative function that matches the same compiled patterns in a dif-
ferent way. In certain circumstances, the alternative function has some
- advantages. For a discussion of the two matching algorithms, see the
+ advantages. For a discussion of the two matching algorithms, see the
pcre2matching page.
- Details of exactly which Perl regular expression features are and are
- not supported by PCRE2 are given in separate documents. See the
- pcre2pattern and pcre2compat pages. There is a syntax summary in the
+ Details of exactly which Perl regular expression features are and are
+ not supported by PCRE2 are given in separate documents. See the
+ pcre2pattern and pcre2compat pages. There is a syntax summary in the
pcre2syntax page.
- Some features of PCRE2 can be included, excluded, or changed when the
- library is built. The pcre2_config() function makes it possible for a
- client to discover which features are available. The features them-
+ Some features of PCRE2 can be included, excluded, or changed when the
+ library is built. The pcre2_config() function makes it possible for a
+ client to discover which features are available. The features them-
selves are described in the pcre2build page. Documentation about build-
- ing PCRE2 for various operating systems can be found in the README and
+ ing PCRE2 for various operating systems can be found in the README and
NON-AUTOTOOLS_BUILD files in the source distribution.
- The libraries contains a number of undocumented internal functions and
- data tables that are used by more than one of the exported external
- functions, but which are not intended for use by external callers.
- Their names all begin with "_pcre2", which hopefully will not provoke
+ The libraries contains a number of undocumented internal functions and
+ data tables that are used by more than one of the exported external
+ functions, but which are not intended for use by external callers.
+ Their names all begin with "_pcre2", which hopefully will not provoke
any name clashes. In some environments, it is possible to control which
- external symbols are exported when a shared library is built, and in
+ external symbols are exported when a shared library is built, and in
these cases the undocumented symbols are not exported.
SECURITY CONSIDERATIONS
- If you are using PCRE2 in a non-UTF application that permits users to
- supply arbitrary patterns for compilation, you should be aware of a
+ If you are using PCRE2 in a non-UTF application that permits users to
+ supply arbitrary patterns for compilation, you should be aware of a
feature that allows users to turn on UTF support from within a pattern.
- For example, an 8-bit pattern that begins with "(*UTF)" turns on UTF-8
- mode, which interprets patterns and subjects as strings of UTF-8 code
+ For example, an 8-bit pattern that begins with "(*UTF)" turns on UTF-8
+ mode, which interprets patterns and subjects as strings of UTF-8 code
units instead of individual 8-bit characters. This causes both the pat-
- tern and any data against which it is matched to be checked for UTF-8
- validity. If the data string is very long, such a check might use suf-
- ficiently many resources as to cause your application to lose perfor-
+ tern and any data against which it is matched to be checked for UTF-8
+ validity. If the data string is very long, such a check might use suf-
+ ficiently many resources as to cause your application to lose perfor-
mance.
- One way of guarding against this possibility is to use the pcre2_pat-
- tern_info() function to check the compiled pattern's options for
- PCRE2_UTF. Alternatively, you can set the PCRE2_NEVER_UTF option when
- calling pcre2_compile(). This causes a compile time error if the pat-
+ One way of guarding against this possibility is to use the pcre2_pat-
+ tern_info() function to check the compiled pattern's options for
+ PCRE2_UTF. Alternatively, you can set the PCRE2_NEVER_UTF option when
+ calling pcre2_compile(). This causes a compile time error if the pat-
tern contains a UTF-setting sequence.
- The use of Unicode properties for character types such as \d can also
- be enabled from within the pattern, by specifying "(*UCP)". This fea-
+ The use of Unicode properties for character types such as \d can also
+ be enabled from within the pattern, by specifying "(*UCP)". This fea-
ture can be disallowed by setting the PCRE2_NEVER_UCP option.
- If your application is one that supports UTF, be aware that validity
- checking can take time. If the same data string is to be matched many
- times, you can use the PCRE2_NO_UTF_CHECK option for the second and
+ If your application is one that supports UTF, be aware that validity
+ checking can take time. If the same data string is to be matched many
+ times, you can use the PCRE2_NO_UTF_CHECK option for the second and
subsequent matches to avoid running redundant checks.
The use of the \C escape sequence in a UTF-8 or UTF-16 pattern can lead
- to problems, because it may leave the current matching point in the
- middle of a multi-code-unit character. The PCRE2_NEVER_BACKSLASH_C op-
+ to problems, because it may leave the current matching point in the
+ middle of a multi-code-unit character. The PCRE2_NEVER_BACKSLASH_C op-
tion can be used by an application to lock out the use of \C, causing a
- compile-time error if it is encountered. It is also possible to build
+ compile-time error if it is encountered. It is also possible to build
PCRE2 with the use of \C permanently disabled.
- Another way that performance can be hit is by running a pattern that
- has a very large search tree against a string that will never match.
- Nested unlimited repeats in a pattern are a common example. PCRE2 pro-
- vides some protection against this: see the pcre2_set_match_limit()
- function in the pcre2api page. There is a similar function called
+ Another way that performance can be hit is by running a pattern that
+ has a very large search tree against a string that will never match.
+ Nested unlimited repeats in a pattern are a common example. PCRE2 pro-
+ vides some protection against this: see the pcre2_set_match_limit()
+ function in the pcre2api page. There is a similar function called
pcre2_set_depth_limit() that can be used to restrict the amount of mem-
ory that is used.
USER DOCUMENTATION
- The user documentation for PCRE2 comprises a number of different sec-
- tions. In the "man" format, each of these is a separate "man page". In
- the HTML format, each is a separate page, linked from the index page.
- In the plain text format, the descriptions of the pcre2grep and
+ The user documentation for PCRE2 comprises a number of different sec-
+ tions. In the "man" format, each of these is a separate "man page". In
+ the HTML format, each is a separate page, linked from the index page.
+ In the plain text format, the descriptions of the pcre2grep and
pcre2test programs are in files called pcre2grep.txt and pcre2test.txt,
- respectively. The remaining sections, except for the pcre2demo section
- (which is a program listing), and the short pages for individual func-
- tions, are concatenated in pcre2.txt, for ease of searching. The sec-
+ respectively. The remaining sections, except for the pcre2demo section
+ (which is a program listing), and the short pages for individual func-
+ tions, are concatenated in pcre2.txt, for ease of searching. The sec-
tions are as follows:
pcre2 this document
@@ -165,24 +166,23 @@ USER DOCUMENTATION
pcre2test description of the pcre2test command
pcre2unicode discussion of Unicode and UTF support
- In the "man" and HTML formats, there is also a short page for each C
+ In the "man" and HTML formats, there is also a short page for each C
library function, listing its arguments and results.
AUTHOR
Philip Hazel
- University Computing Service
+ Retired from University Computing Service
Cambridge, England.
- Putting an actual email address here is a spam magnet. If you want to
- email me, use my two initials, followed by the two digits 10, at the
- domain cam.ac.uk.
+ Putting an actual email address here is a spam magnet. If you want to
+ email me, use my two names separated by a dot at google.com.
REVISION
- Last updated: 28 April 2021
+ Last updated: 25 August 2021
Copyright (c) 1997-2021 University of Cambridge.
------------------------------------------------------------------------------