
[![logo][logo-url]][reflex-url]

[![build status][travis-image]][travis-url] [![Language grade: C/C++][lgtm-image]][lgtm-url] [![license][bsd-3-image]][bsd-3-url] [![CodeProject][codeproject-image]][codeproject-url]

The regex-centric, fast lexical analyzer generator for C++ with full Unicode
support.

[RE/flex][reflex-url] is faster than Flex while providing a wealth of new
features and contributions.  RE/flex is also much faster than regex libraries
such as Boost.Regex, C++11 std::regex, PCRE2 and RE2.  For example, tokenizing
a 2 KB representative C source code file into 244 tokens takes only 8
microseconds:

<table>
<tr><th>Command / Function</th><th>Software</th><th>Time (μs)</th></tr>
<tr><td><b>reflex --fast --noindent</b></td><td><b>RE/flex 2.0.0</b></td><td><b>8</b></td></tr>
<tr><td><b>reflex --fast</b></td><td><b>RE/flex 2.0.0</b></td><td><b>9</b></td></tr>
<tr><td>flex -+ --full</td><td>Flex 2.5.35</td><td>17</td></tr>
<tr><td>reflex --full</td><td>RE/flex 2.0.0</td><td>18</td></tr>
<tr><td>boost::spirit::lex::lexertl::actor_lexer::iterator_type</td><td>Boost.Spirit.Lex 1.66.0</td><td>40</td></tr>
<tr><td>pcre2_jit_match()</td><td>PCRE2 (jit) 10.32</td><td>60</td></tr>
<tr><td>hs_compile_multi(), hs_scan()</td><td>Hyperscan 5.1.0</td><td>209</td></tr>
<tr><td>reflex -m=boost-perl</td><td>Boost.Regex 1.66.0</td><td>230</td></tr>
<tr><td>pcre2_match()</td><td>PCRE2 10.32</td><td>318</td></tr>
<tr><td>RE2::Consume()</td><td>RE2 (pre-compiled) 2018-04-01</td><td>417</td></tr>
<tr><td>reflex -m=boost</td><td>Boost.Regex POSIX 1.66.0</td><td>450</td></tr>
<tr><td>RE2::Consume()</td><td>RE2 POSIX (pre-compiled) 2018-04-01</td><td>1226</td></tr>
<tr><td>flex -+</td><td>Flex 2.5.35</td><td>3968</td></tr>
<tr><td>pcre2_dfa_match()</td><td>PCRE2 POSIX (dfa) 10.32</td><td>4094</td></tr>
<tr><td>regcomp(), regexec()</td><td>GNU C POSIX.2 regex</td><td>5800</td></tr>
<tr><td>std::cregex_iterator()</td><td>C++11 std::regex</td><td>5979</td></tr>
</table>

Note: *Best times of 30 tests with average time in microseconds over 100 runs
using Mac OS X 10.12.6 clang 9.0.0 -O2, 2.9 GHz Intel Core i7, 16 GB 2133 MHz
LPDDR3.  Hyperscan disqualifies as a scanner due to its "All matches reported"
semantics resulting in 1915 matches for this test, and due to its event handler
requirements.* [Download the tests](https://www.genivia.com/files/perfcomp.zip)
*Timings on other platforms may differ, though in the worst cases tested,
reflex ran equally fast or slightly faster than the best times of Flex.*

The RE/flex matcher tracks line numbers, column numbers, and indentations,
whereas Flex does not (option noyylineno) and neither do the other regex
matchers in the table, except Boost.Regex with reflex.  Tracking this
information incurs some overhead.


Features
--------

- Compatible with Flex to eliminate a learning curve, making a transition from
  Flex++ to RE/flex frustration-free.
- Generates reusable source code that is easy to understand.
- Integrates seamlessly with Bison and supports reentrant, bison-bridge,
  bison-locations, Bison 3.0 C++ interface `%skeleton "lalr1.cc"` and Bison
  complete symbols.
- Fully supports Unicode and Unicode properties `\p{C}`, including Unicode
  identifier matching for C++11, Java, C#, and Python source code.
- Auto-detects UTF-8/16/32 input to match Unicode patterns.
- Supports file encodings ISO-8859-1 through ISO-8859-15, CP 1250 through 1258,
  CP 437, CP 850, CP 858, KOI8, MACROMAN, EBCDIC, and custom code pages.
- Generates scanners for lexical analysis on files, C++ streams, (wide)
  strings, and memory such as mmap files.
- Includes many examples, such as a mini C compiler to Java bytecode, a
  tokenizer for C/C++ source code, a tokenizer for Python source code, a
  tokenizer for Java source code, and more.
- Extensive documentation in the online [User Guide][manual-url].
- Indent/nodent/dedent anchors to match text with indentation, including
  custom `\t` (tab) widths.
- Lazy quantifiers, no hacks are needed to work around greedy repetitions.
- Word boundary anchors.
- Freespace mode option to improve readability of lexer specifications.
- `%class` and `%init` to customize the generated Lexer classes.
- `%include` to modularize lexer specifications.
- Multiple lexer classes can be combined and used in one application, e.g. by
  multiple threads in a thread-safe manner.
- Configurable Lexer class generation to customize the interface for various
  parsers, including Yacc and Bison.
- Generates Graphviz files to visualize FSMs with the Graphviz dot tool.
- Includes an extensible hierarchy of pattern matcher engines, with a choice of
  regex engines, including the RE/flex regex engine, PCRE2, and Boost.Regex.
- The RE/flex regex library makes C++11 std::regex, PCRE2, and Boost.Regex much
  easier to use for pattern matching on (wide) strings, files, and streams.
- Lots of other improvements over Flex++, such as `yypush_buffer_state` saves
  the scanner state (line, column, and indentation positions), not just the
  input buffer; no input buffer length limit (Flex has a 16KB limit); `line()`
  returns the current line (e.g. for error reporting).

The RE/flex software is fully self-contained.  No other libraries are required.
PCRE2 and Boost.Regex are optional to use as regex engines.

The RE/flex repo includes tokenizers for Java, Python, C/C++, JSON, XML, YAML.


Installation
------------

### Windows users

Use `reflex/bin/reflex.exe` from the command line or add a **Custom Build
Step** in MSVC++ as follows:

1. select the project name in **Solution Explorer** then **Property Pages**
   from the **Project** menu (see also
   [custom-build steps in Visual Studio](http://msdn.microsoft.com/en-us/library/hefydhhy.aspx));

2. add an extra path to the `reflex/include` folder in the **Include
   Directories** under **VC++ Directories**, which should look like
   `$(VC_IncludePath);$(WindowsSDK_IncludePath);C:\Users\YourUserName\Documents\reflex\include`
   (this assumes the `reflex` source package is in your **Documents** folder).

3. enter `"C:\Users\YourUserName\Documents\reflex\bin\win32\reflex.exe" --header-file
   "C:\Users\YourUserName\Documents\mylexer.l"` in the **Command Line** property
   under **Custom Build Step** (this assumes `mylexer.l` is in your
   **Documents** folder);

4. enter `lex.yy.h lex.yy.cpp` in the **Outputs** property;

5. specify **Execute Before** as `PreBuildEvent`.

If you are using specific reflex options such as `--flex` then add these in step 3.

Before compiling your program with MSVC++, drag the folders `reflex/lib` and
`reflex/unicode` to the **Source Files** in the **Solution Explorer** panel of
your project.  Next, run `reflex.exe` simply by compiling your project (which
may fail, but that is OK for now as long as we executed the custom build step
to run `reflex.exe`).  Drag the generated `lex.yy.h` (if present) and
`lex.yy.cpp` files to the **Source Files**.  Now you are all set!

In addition, the `reflex/vs` directory contains batch scripts to build projects
with MS Visual Studio C++.

### Unix/Linux and Mac OS X

On macOS systems you can use [homebrew](https://brew.sh) to install RE/flex
with `brew install re-flex`.

On NetBSD systems you can use the standard NetBSD package installer (pkgsrc):
<http://cdn.netbsd.org/pub/pkgsrc/current/pkgsrc/devel/RE-flex/README.html>

Otherwise, you have two options: 1) quick install or 2) configure and make.

**Note:** GCC 8 and greater may produce warnings of the sort *"note: parameter
passing for argument ... changed in GCC 7.1"*.  These warnings should be
ignored.

### Quick install

First clone the code:

    $ git clone https://github.com/Genivia/RE-flex

Then simply do a quick clean build, assuming your environment is pretty much
standard:

    $ sh clean.sh
    $ sh build.sh

This compiles the **reflex** tool and installs it locally in `reflex/bin`.  For
local use of RE/flex in your project, you can add this location to your `$PATH`
variable to enable the new `reflex` command:

    $ export PATH=$PATH:/your_path_to_reflex/reflex/bin

Note that the `libreflex.a` and `libreflex.so` libraries are saved locally in
`reflex/lib`.  Link against the library when you use the RE/flex regex engine
in your code, such as:

    $ c++ <options and .o/.cpp files> -L/your_path_to_reflex/reflex/lib -lreflex

or you could statically link libreflex.a with:

    $ c++ <options and .o/.cpp files> /your_path_to_reflex/reflex/lib/libreflex.a

Also note that the RE/flex header files that you will need to include in your
project are locally located in `include/reflex`.

To install the man page, the header files in `/usr/local/include/reflex`, the
library in `/usr/local/lib` and the `reflex` command in `/usr/local/bin`:

    $ sudo sh allinstall.sh

### Configure and make

The configure script accepts configuration and installation options.  To view
these options, run:

    $ ./configure --help

Run configure and make:

    $ ./configure && make

To build the examples also:

    $ ./configure --enable-examples && make

After this successfully completes, you can optionally run `make install` to
install the `reflex` command and `libreflex` library:

    $ sudo make install

Unfortunately, cloning from Git does not preserve timestamps which means that
you may run into "WARNING: 'aclocal-1.15' is missing on your system."  To
work around this problem, run:

    $ autoreconf -fi
    $ ./configure && make

### Optional libraries to install

- To use PCRE2 as a regex engine with the RE/flex library and scanner
  generator, install [PCRE2][pcre-url] and link your code with `-lpcre2-8`.

- To use Boost.Regex as a regex engine with the RE/flex library and scanner
  generator, install [Boost][boost-url] and link your code with
  `-lboost_regex` or `-lboost_regex-mt`.

- To visualize the FSM graphs generated with **reflex** option `--graphs-file`,
  install [Graphviz dot][dot-url].

### Improved Vim syntax highlighting

Copy the `lex.vim` file to `~/.vim/syntax/` to enjoy improved syntax
highlighting for both Flex and RE/flex.


Usage
-----

There are two ways you can use this project:

1. as a scanner generator for C++, similar to Flex;
2. as a flexible regex matching API for C++.

For the first option, simply build the **reflex** tool and run it on the
command line on a lexer specification:

    $ reflex --flex --bison --graphs-file lexspec.l

This generates a scanner for Bison from the lexer specification `lexspec.l` and
saves the finite state machine (FSM) as a Graphviz `.gv` file that can be
visualized with the [Graphviz dot][dot-url] tool:

    $ dot -Tpdf reflex.INITIAL.gv > reflex.INITIAL.pdf
    $ open reflex.INITIAL.pdf

![Visualize DFA graphs with Graphviz dot][FSM-url]

Several examples are included to get you started.  See the [manual][manual-url]
for more details.

For the second option, simply use the RE/flex matcher API classes to start
pattern matching on strings, wide strings, files, and streams.

You can select matchers that are based on different regex engines:

- RE/flex regex: `#include <reflex/matcher.h>` and use `reflex::Matcher`;
- PCRE2: `#include <reflex/pcre2matcher.h>` and use `reflex::PCRE2Matcher` or
  `reflex::PCRE2UTFMatcher`.
- Boost.Regex: `#include <reflex/boostmatcher.h>` and use
  `reflex::BoostMatcher` or `reflex::BoostPosixMatcher`;
- C++11 std::regex: `#include <reflex/stdmatcher.h>` and use
  `reflex::StdMatcher` or `reflex::StdPosixMatcher`.

Each matcher may differ in regex syntax features (see the full documentation),
but they all share the same methods and iterators, such as:

- `matches()` returns nonzero if the input matches the specified pattern;
- `find()` search input and returns nonzero if a match was found;
- `scan()` scan input and returns nonzero if input at current position matches;
- `split()` returns nonzero for a split of the input at the next match;
- `find.begin()`...`find.end()` filter iterator;
- `scan.begin()`...`scan.end()` tokenizer iterator;
- `split.begin()`...`split.end()` splitter iterator.

For example, using Boost.Regex (alternatively use PCRE2 `reflex::PCRE2Matcher`):

```{.cpp}
#include <reflex/boostmatcher.h> // reflex::BoostMatcher, reflex::Input, boost::regex
// use a BoostMatcher to check if the birthdate string is a valid date
if (reflex::BoostMatcher("\\d{4}-\\d{2}-\\d{2}", birthdate).matches() != 0)
  std::cout << "Valid date!" << std::endl;
```

With a group capture to fetch the year:

```{.cpp}
#include <reflex/boostmatcher.h> // reflex::BoostMatcher, reflex::Input, boost::regex
// use a BoostMatcher to check if the birthdate string is a valid date
reflex::BoostMatcher matcher("(\\d{4})-\\d{2}-\\d{2}", birthdate);
if (matcher.matches() != 0)
  std::cout << std::string(matcher[1].first, matcher[1].second) << " was a good year!" << std::endl;
```

To search a string for words `\w+`:

```{.cpp}
#include <reflex/boostmatcher.h> // reflex::BoostMatcher, reflex::Input, boost::regex
// use a BoostMatcher to search for words in a sentence
reflex::BoostMatcher matcher("\\w+", "How now brown cow.");
while (matcher.find() != 0)
  std::cout << "Found " << matcher.text() << std::endl;
```

The `split` method is roughly the inverse of the `find` method and returns text
located between matches.  For example using non-word matching `\W+`:

```{.cpp}
#include <reflex/boostmatcher.h> // reflex::BoostMatcher, reflex::Input, boost::regex
// use a BoostMatcher to search for words in a sentence
reflex::BoostMatcher matcher("\\W+", "How now brown cow.");
while (matcher.split())
  std::cout << "Found " << matcher.text() << std::endl;
```

To pattern match the content of a file, where the file may use UTF-8, 16, or 32
encodings that are automatically converted when a UTF BOM is present:

```{.cpp}
#include <reflex/boostmatcher.h> // reflex::BoostMatcher, reflex::Input, boost::regex
// use a BoostMatcher to search and display words from a FILE
FILE *fd = fopen("somefile.txt", "r");
if (fd == NULL)
  exit(EXIT_FAILURE);
reflex::BoostMatcher matcher("\\w+", fd);
while (matcher.find())
  std::cout << "Found " << matcher.text() << std::endl;
fclose(fd);
```

Same again, but this time with a C++ input stream:

```{.cpp}
#include <reflex/boostmatcher.h> // reflex::BoostMatcher, reflex::Input, boost::regex
// use a BoostMatcher to search and display words from a stream
std::ifstream file("somefile.txt", std::ifstream::in);
reflex::BoostMatcher matcher("\\w+", file);
while (matcher.find())
  std::cout << "Found " << matcher.text() << std::endl;
file.close();
```

Stuffing the search results into a container using RE/flex iterators:

```{.cpp}
#include <reflex/boostmatcher.h> // reflex::BoostMatcher, reflex::Input, boost::regex
#include <vector>         // std::vector
// use a BoostMatcher to convert words of a sentence into a string vector
reflex::BoostMatcher matcher("\\w+", "How now brown cow.");
std::vector<std::string> words(matcher.find.begin(), matcher.find.end());
```

Use C++11 range-based loops with RE/flex iterators:

```{.cpp}
#include <reflex/stdmatcher.h> // reflex::StdMatcher, reflex::Input, std::regex
// use a StdMatcher with std::regex to search for words in a sentence
reflex::StdMatcher matcher("\\w+", "How now brown cow.");
for (auto& match : matcher.find)
  std::cout << "Found " << match.text() << std::endl;
```

RE/flex also allows you to convert expressive regex syntax forms such as `\p`
Unicode classes, character class set operations such as `[a-z--[aeiou]]`,
escapes such as `\X`, and `(?x)` mode modifiers, to a regex string that the
underlying regex library understands and will be able to use:

- `std::string reflex::Matcher::convert(const std::string& regex, reflex::convert_flag_type flags)`
- `std::string reflex::PCRE2Matcher::convert(const std::string& regex, reflex::convert_flag_type flags)`
- `std::string reflex::BoostMatcher::convert(const std::string& regex, reflex::convert_flag_type flags)`
- `std::string reflex::StdMatcher::convert(const std::string& regex, reflex::convert_flag_type flags)`

For example:

```{.cpp}
#include <reflex/matcher.h> // reflex::Matcher, reflex::Input, reflex::Pattern
// use a Matcher to check if sentence is in Greek:
static const reflex::Pattern pattern(reflex::Matcher::convert("[\\p{Greek}\\p{Zs}\\pP]+", reflex::convert_flag::unicode));
if (reflex::Matcher(pattern, sentence).matches() != 0)
  std::cout << "This is Greek" << std::endl;
```

We use `convert` with optional flag `reflex::convert_flag::unicode` to make `.`
(dot), `\w`, `\s` and so on match Unicode and to convert `\p` Unicode character
classes.

Conversion is fast (it runs in linear time in the size of the regex), but it is
not without some overhead.  Making converted regex patterns `static` as shown
above saves the cost of conversion to just once to support many matchings.


How to contribute?
------------------

Please see [CONTRIBUTING](CONTRIBUTING.md).


Where do I find the documentation?
----------------------------------

Read more about RE/flex in the [manual][manual-url].


License and copyright
---------------------

RE/flex by Robert van Engelen, Genivia Inc.
Copyright (c) 2016-2020, All rights reserved.

RE/flex is distributed under the BSD-3 license LICENSE.txt.
Use, modification, and distribution are subject to the BSD-3 license.


Reporting bugs
--------------

Visit GitHub to report bugs: https://github.com/Genivia/RE-flex


Changelog
---------

- Nov 14, 2016: 0.9.0  beta released
- Nov 15, 2016: 0.9.1  improved portability
- Nov 17, 2016: 0.9.2  improvements and fixes for minor issues
- Nov 19, 2016: 0.9.3  replaces `%import` with `%include`, adds freespace option `-x`, fixes minor issues
- Nov 20, 2016: 0.9.4  fixes minor issues, added new examples/json.l
- Nov 25, 2016: 0.9.5  bug fixes and improvements
- Dec  1, 2016: 0.9.6  portability improvements
- Dec  6, 2016: 0.9.7  bug fixes, added option `--regexp-file`, Python tokenizer
- Dec  9, 2016: 0.9.8  fixes minor issues, improved reflex tool options `--full` and `--fast`, generates scanner with FSM table or a fast scanner with FSM code, respectively
- Jan  8, 2017: 0.9.9  bug fixes and improved Flex compatibility
- Jan 15, 2017: 0.9.10 improved compatibility with Flex options, fixed critical issue with range unions
- Jan 25, 2017: 0.9.11 added C++11 std::regex matching engine support, moved .h files to include/reflex, requires `#include <reflex/xyz.h>` from now on, fixed `errno_t` portability issue
- Mar  3, 2017: 0.9.12 refactored and improved, includes new regex converters for regex engines that lack regex features such as Unicode character classes
- Mar  4, 2017: 0.9.13 improved warning and error messages
- Mar  6, 2017: 0.9.14 reflex option `-v` shows stats with execution timings, bug fixes
- Mar  8, 2017: 0.9.15 added `wtext()`, `wpair()`, `winput()` methods, other improvements
- Mar 22, 2017: 0.9.16 bug fixes, speed improvements, improved option `--unicode` regex conversion, also with `(?u:)`, changed `wtext()` to `wstr()` and added a `str()` method
- Mar 24, 2017: 0.9.17 improvements
- Mar 26, 2017: 0.9.18 added reflex option `-p` (`--perf-report`) for performance debugging, added doc/man/reflex.1 man page, added interactive readline example
- Mar 31, 2017: 0.9.19 fixed reflex option `-m`, `lexer.in(i)` now resets the lexer, fixed reassigning the same input to the lexer that caused UTF BOM to be read twice
- Apr  5, 2017: 0.9.20 EBCDIC file translation, other improvements
- Apr 10, 2017: 0.9.21 fixed option `-P` to support multiple lexer classes in one application, added `configure` installation script, optional quick install with `allinstall.sh` (renamed from `install.sh`)
- Apr 12, 2017: 0.9.22 improved explanations of `matches()`, `find()`, `scan()`, `split()` that return nonzero for a match, other minor improvements
- May 24, 2017: 0.9.23 improved portability, added file encoding conversions for CP-1250 to CP-1258, CP 437, and CP 850/858
- Jun 24, 2017: 0.9.24 added an option for users to define their own custom code pages to translate input, fixed `#` in free space mode
- Jun 28, 2017: 0.9.25 fixed `--fast` FSM not always halting on EOF after a mismatch; fixed buffer realloc, added new examples/csv.l
- Jul  5, 2017: 0.9.26 fixed `wstr()` always returning UTF-16 strings (should be UTF-16 only when `std::wstring` requires it)
- Sep 26, 2017: 0.9.27 the Flex-compatible `yy_scan_string()`, `yy_scan_bytes()` and `yy_scan_buffer()` functions now create a new buffer as in Flex, delete this buffer with `yy_delete_buffer()`; fixed examples to work with newer Bison versions (Bison 3.0.4)
- Dec 12, 2017: 0.9.28 added `yy_scan_wstring` and `yy_scan_wbuffer` for wide string scanning with Flex-like functions
- Jan 28, 2018: 1.0.0 removed dynamic exception specifications to comply with C++17, upgraded to stable release 1.0
- Feb 24, 2018: 1.0.1 added Unicode IsBlockName categories
- Mar  6, 2018: 1.0.2 added namespace nesting with `%option namespace=NAME1.NAME2.NAME3 ...`
- Mar  7, 2018: 1.0.3 fixed `--namespace` and `%option namespace`
- Apr 22, 2018: 1.0.4 updated to Unicode 10, cleaned up code to remove tool warnings
- Jun 29, 2018: 1.0.5 updated `--namespace` for options `--fast` and `--full` to support the generation of multiple optimized lexers placed in namespaces.
- Jul  9, 2018: 1.0.6 added `--bison-cc` option to generate scanners for Bison 3.0 `%skeleton "lalr1.cc"` C++ parsers, included two examples `flexexample9xx` and `reflexexample9xx` to demo this feature.
- Jul 12, 2018: 1.0.7 added `--bison-cc-namespace` and `--bison-cc-parser` options to customize Bison 3.0 `%skeleton "lalr1.cc"` C++ parsers.
- Jul 30, 2018: 1.0.8 updated to Unicode 11.
- Aug 21, 2018: 1.0.9 fixed reflex regex library matching with range quantifiers by correcting coding typo.
- Dec  8, 2018: 1.0.10 fixed `columno()` to take tab spacing into account.
- Jan 18, 2019: 1.0.11 fixed GCC 8.2 warnings, additional enhancements.
- Jan 21, 2019: 1.0.12 the reflex tool now reads files using `reflex::Input`.
- Feb 20, 2019: 1.1.0 code quality updates.
- Mar  6, 2019: 1.1.1 fixed `configure` and `make install` header files, updated `--bison-locations` option.
- Mar  7, 2019: 1.1.2 fixed reflex tool handling of backslashes in file paths.
- Mar 11, 2019: 1.1.3 updated to Unicode 12, examples can now be built with `./configure --enable-examples`.
- Mar 27, 2019: 1.1.4 fixed reflex tool common top code block insertion for all inclusive states.
- Apr  6, 2019: 1.1.5 improved reflex tool command-line option handling, updated documentation.
- Apr 29, 2019: 1.2.0 added `--bison-complete` option, new ugrep utility example, updated manual, fixes minor issues.
- May 15, 2019: 1.2.1 added `reflex::convert_flag::basic` to convert BRE syntax to ERE syntax, used by [ugrep](https://github.com/Genivia/ugrep).
- May 28, 2019: 1.2.2 fixed MinGW builds, fixed `reflex::Input::get()` to return positive character code, matcher option `"N"` for `scan` and `find` matches empty input (`^$`).
- Jun 21, 2019: 1.2.3 fixed reflex long regex string generation, namespaces with option `--full`, updated documentation and other improvements.
- Jun 24, 2019: 1.2.4 fixed an issue with `reflex::StdMatcher` (`std::regex`) causing failures to match input with `split`.
- Jul  2, 2019: 1.2.5 added `reflex::Input::in(const char *memptr, size_t memlen)` to read a memory segment (for scanning etc.), added `reflex::Input::streambuf` class to use a `reflex::Input` object as a `std::streambuf`, improved `yy_scan_buffer` and `yy_scan_bytes`.
- Jul  3, 2019: 1.2.6 fixed a problem with lazy quantifiers used within negative patterns.
- Jul  4, 2019: 1.2.7 added `reflex::Input::dos_streambuf` to convert DOS CRLF to LF, other improvements.
- Jul  8, 2019: 1.2.8 added support for inverted mode modifiers `(?-imsux)` to `reflex::convert` and `reflex::Pattern`.
- Jul 11, 2019: 1.2.9 portability improvements.
- Jul 14, 2019: 1.2.10 added `AbstractMatcher::set_bob()`, moved `AbstractMatcher::peek()` to public, minor improvements.
- Jul 21, 2019: 1.3.0 added subtractive start condition scoping with `<^...>`, added undent `\k` anchor to undo indenting changes ("undenting") with an example in `examples/indent2.l`, improved indent `\i` and dedent `\j` anchors and other improvements.
- Jul 24, 2019: 1.3.1 added `matcher().tabs(n)` to set tab size, used by `columno()` and indent `\i` and dedent `\j` anchors, new `reflex::Pattern` methods, other improvements.
- Jul 27, 2019: 1.3.2 added defined name expansion in bracket lists for the union `||`, intersection `&&`, and subtraction `--` operations, e.g. `[||{letter}||{digit}]` expands into `[a-zA-Z0-9]` when `letter` is defined as `[a-zA-Z]` and `digit` is defined as `[0-9]`, see Character Classes in the documentation.
- Aug  5, 2019: 1.3.3 fixed `reflex::BoostMatcher` (and derived `reflex::BoostPosixMatcher`, `reflex::BoostPerlMatcher`) regression bug that crept into the 1.2.4 update.
- Aug  7, 2019: 1.3.4 speed improvements for non-fast options.
- Aug  8, 2019: 1.3.5 further speed improvements for both fast and non-fast options (15% to 30% faster).
- Aug 12, 2019: 1.3.6 added lexer and matcher `buffer(base, size)` methods and improved Flex-compatible `yy_scan_buffer(base, size)`, these functions scan memory fast with zero copy overhead; added `mmap.l` example to scan an mmap-ed file fast with mmap(2) and `buffer(base, size)`; other improvements.
- Aug 16, 2019: 1.3.7 added `reflex::BufferedInput::dos_streambuf` to improve `dos_streambuf` speed by buffering (`reflex::Input::dos_streambuf` is unbuffered), fixed `%option token-type` to apply without restrictions.
- Aug 17, 2019: 1.3.8 added caching of `lineno()` and `columno()` to increase speed, which is essential for large buffers such as large mmap-ed files scanned with `buffer(base, size)`; other improvements.
- Sep  4, 2019: 1.4.0 added reflex option `-S` (`--find`) for efficient searching instead of scanning input (i.e. efficiently ignoring unmatched input) demonstrated with new `findfast` and `findsearch` examples; changed `--nodefault` to throw an exception when option `--flex` is not used and when the default rule is triggered.
- Sep 10, 2019: 1.4.1 fixed `lineno()` caching issue (1.3.8 bug); faster `find`.
- Sep 15, 2019: 1.4.2 faster `find` for patterns beginning with optional repetitions such as `.*`.
- Sep 29, 2019: 1.4.3 added `reflex::AbstractMatcher::clone()` to clone a referenced concrete matcher object.
- Oct 23, 2019: 1.4.4 improved option `--flex` for Flex compatibility; fixed option `--token-type` with option `--flex`, now properly defines `YY_NULL` and `yyterminate`; fixed `AbstractMatcher::buffer(n)` for large `n`; faster `find`.
- Nov  5, 2019: 1.5.0 added `border()`, `span()`, `line()`, `wline()`, and `skip(c)` methods; added new section on error reporting and recovery to the documentation; fixed `yy_scan_string()` and `yy_scan_buffer()` when called before calling `yylex()` for the first time; improved performance.
- Nov  7, 2019: 1.5.1 improvements; added `dos.l` demo example of `reflex::InputBuffer::dos_streambuf`.
- Nov 12, 2019: 1.5.2 fixed an internal buffer allocation issue that may cause a crash when input lines are longer than 16KB (regression bug that crept into in 1.5.0).
- Nov 21, 2019: 1.5.3 added `lineno_end()` and `columno_end()` methods, updated `columns()` with clarifications in the updated documentation; expanded the documentation with additional error reporting and handling techniques with RE/flex and Bison bridge and complete configurations; FSM code generation improvements.
- Nov 22, 2019: 1.5.4 added `flexexample11xx` example with Flex specification and Bison complete parser; minor improvements.
- Dec 23, 2019: 1.5.5 expanded the `skip(c)` methods with a `wchar_t` wide character parameter and a UTF-8 string parameter to skip input; added new option `--token-eof`.
- Dec 28, 2019: 1.5.6 added new option `--noindent` to speed up pattern matching and lexical analysis by disabling indentation tracking in the input (also disables anchors `\i`, `\j`, and `\k`); speed improvements.
- Jan 19, 2020: 1.5.7 expanded file encoding formats to include ISO-8859-2 to 16, MacRoman, KOI8; fixed a bug in `line()` and `span()`.
- Feb  3, 2020: 1.5.8 added `wunput()` method; added `lex.vim` improved Flex and RE/flex Vim syntax highlighting; added `yaml.l` example; fixed `--freespace` with `--unicode` when bracket lists contain a `#`; character class operators `{+}`, `{-}`, `{&}` now accept defined names as first operands and inverted character classes; indent anchor `\k` now matches only when indent level is changed as documented.
- Mar  2, 2020: 1.6.0 added PCRE2 regex matcher classes and updated reflex option `--matcher=pcre2-perl`; optimized RE/flex matcher `find()` with AVX/SSE2/NEON/AArch64; updated and improved regex converters.
- Mar  3, 2020: 1.6.1 fixed missing PCRE2 regex type `std::string` in generated scanners.
- Mar 10, 2020: 1.6.2 improved `reflex::PCRE2Matcher`; fixed MSVC++ x86 32-bit build error when `HAVE_AVX512BW` is enabled (requires AVX512BW).
- Mar 19, 2020: 1.6.3 updated to Unicode 13; fixed start condition scope specifications for patterns that start with a `{`; updated lex.vim.
- Mar 22, 2020: 1.6.4 added option `--yy` to enable `--flex` and `--bison`, but also defines the global `FILE*` variables `yyin` and `yyout` for enhanced Lex/Flex compatibility (`yyin` is otherwise a pointer to the `reflex::Input` object to read files, streams, and strings).
- Mar 23, 2020: 1.6.5 updated to permit `}` as closing marker for `%top{`, `%class{`, and `%init{` code blocks, i.e. `%}` or `}` may be used as closing markers.
- Mar 31, 2020: 1.6.6 fixed an issue where a trailing backslash in a pattern in a lexer specification causes a reflex-generated C++ comment to extend to the next line, which results in a compilation warning and possibly a line of code being skipped.
- Apr 30, 2020: 1.6.7 minor improvements to parse and convert regex patterns to FSMs.
- May 14, 2020: 2.0.0 faster FSM construction; new FSM VM opcodes; relaxed limits of pattern length and complexity (max 16,711,679 FSM opcode words, from 65,536 words previously) for high-performance pattern matching with very long and complex regex patterns.
- May 25, 2020: 2.0.1 resolved 64-bit build warnings; fixed reflex CRLF output in C++ source code on Windows.
- Jun 29, 2020: 2.1.0 added Bison complete locations filename member access; added example Mini C compiler `minic` using RE/flex scanner with Bison 3.2 C++ complete locations, compiles C-like source code to Java bytecode (class files); added fast fuzzy (approximate) regex matcher `reflex::FuzzyMatcher` derived from `reflex::Matcher`.
- Jul  8, 2020: 2.1.1 added `%option params` to extend `lex()`/`yylex()` parameters; updated AVX2 detection for SIMD optimizations.
- Jul  9, 2020: 2.1.2 minor update to fix MSVC++ compiler error.
- Aug  3, 2020: 2.1.3 improved `--bison-bridge` option; updated examples.
- Aug 19, 2020: 2.1.4 changed `IN_HEADER` to `yyIN_HEADER` when `--flex` is used with `--header-file`; added `reflex::Input::Handler` event handler for custom handling of `FILE*` errors and non-blocking `FILE*` streams.

[logo-url]: https://www.genivia.com/images/reflex-logo.png
[reflex-url]: https://www.genivia.com/reflex.html
[manual-url]: https://www.genivia.com/doc/reflex/html
[flex-url]: http://dinosaur.compilertools.net/#flex
[lex-url]: http://dinosaur.compilertools.net/#lex
[bison-url]: http://dinosaur.compilertools.net/#bison
[dot-url]: http://www.graphviz.org
[FSM-url]: https://www.genivia.com/images/reflex-FSM.png
[boost-url]: http://www.boost.org
[pcre-url]: http://www.pcre.org
[travis-image]: https://travis-ci.org/Genivia/RE-flex.svg?branch=master
[travis-url]: https://travis-ci.org/Genivia/RE-flex
[lgtm-image]: https://img.shields.io/lgtm/grade/cpp/g/Genivia/RE-flex.svg?logo=lgtm&logoWidth=18
[lgtm-url]: https://lgtm.com/projects/g/Genivia/RE-flex/context:cpp
[bsd-3-image]: https://img.shields.io/badge/license-BSD%203--Clause-blue.svg
[bsd-3-url]: https://opensource.org/licenses/BSD-3-Clause
[codeproject-image]: https://img.shields.io/badge/CodeProject-★★★★★-orange.svg
[codeproject-url]: https://www.codeproject.com/Articles/1180430/Constructing-Fast-Lexical-Analyzers-with-RE-flex-W
