C++Now 2015

C++ Now 2015. Today is the official release of Spirit X3, aka Spirit 3.0.0. X3 will be in beta, coexisting side by side with Qi, Karma, Lex and Classic.

If you are a Qi user, the best place to start are the examples, especially rexpr and x3 fun.

Remember to use a compiler with c++14 capabilities:

• clang 3.4 or greater
• gcc 4.9 or greater

Documents

Docs: X3 Documentation

Slides: Using X3 Slides

Spirit X3 Source

GitHub: git@github.com:boostorg/spirit.git

Use the develop branch.

Zip of develop: develop.zip

You will find boilerplate (getting started) projects in: example/x3/rexpr
There are two directories.

• rexpr_min – contains a single file to start things off.
• rexpr_full – contains a structure similar to the one in the presentation complete with tests.

X3 Fun

GitHub: git@github.com:cierelabs/x3_fun.git

Integer tests

atoi_test:  4.7452590000 [s] {checksum: 213ce33a}
strtol_test: 4.5116520000 [s] {checksum: 213ce33a}
spirit_int_test: 1.4126110000 [s] {checksum: 213ce33a}

Double Tests

atof_test: 3.2435210000 [s] {checksum: 84a4f7d}
strtod_test: 3.1327660000 [s] {checksum: 84a4f7d}
spirit_double_test: 0.7237810000 [s] {checksum: 84a4f7d}

BMC — Braille Music Compiler

BMC translates between braille music code and visual music notation. It uses Boost.Spirit to parse braille music code into an AST which is later enhanced with various algorithms to resolve ambiguities inherent to braille music code. It can currently convert to LilyPond source format, which can later be translated to a PDF and MIDI representation by LilyPond. BMC aims to become an universal translator between tactile and visual music notation, eventually covering both directions. We are looking for developers with a background in music notation who might be interested to contribute to this unique free software project which aims to bridge the gap between blind and sighted musicians.

I Will Always Find You – Tales of C++

http://talesofcpp.fusionfenix.com/post-8/true-story-i-will-always-find-you

https://github.com/djowel/spirit_x3
https://github.com/djowel/spirit_x3.git
git@github.com:djowel/spirit_x3.git

The full attribute mechanism works + basic C++lambda support. I’ve ported one example (calc4.cpp) which parses to an AST. The AST remains the same. Only the way the grammars are written had to change.

For a teaser: here’s GCC times:

SpiritX3: TOTAL :   4.27 secs
Spirit2:  TOTAL :  10.00 secs

Even faster at CT than the first Spirit3 attempt. Runtime speed? I expect it to be faster than Spirit-2. The rules have changed (pun intentional). Now, there’s no longer the need for virtual functions and auto is used extensively. I expect code size to be smaller too because the compiler can generate more efficient code.

Here’s the calculator grammar (based on calc3.cpp):

///////////////////////////////////////////////////////////////////////////////
//  The calculator grammar
///////////////////////////////////////////////////////////////////////////////
namespace calculator_grammar
{
    using x3::uint_;
    using x3::char_;

    x3::rule<class expression, ast::program> const expression;
    x3::rule<class term, ast::program> const term;
    x3::rule<class factor, ast::operand> const factor;

    auto const expression_def =
        term
        >> *(   (char_('+') >> term)
            |   (char_('-') >> term)
            )
        ;

    auto const term_def =
        factor
        >> *(   (char_('*') >> factor)
            |   (char_('/') >> factor)
            )
        ;

    auto const factor_def =
            uint_
        |   '(' >> expression >> ')'
        |   (char_('-') >> factor)
        |   (char_('+') >> factor)
        ;

    auto const calculator = x3::grammar(
            expression = expression_def,
            term = term_def,
            factor = factor_def
        );
}

using calculator_grammar::calculator;

Here’s the abstract:

Inside Spirit X3.Redesigning Boost.Spirit for C++11
Joel de Guzman, 2013

The hugely successful BoostCon ’07 ’08, ’09 and ’10 Spirit talks provided walk-through presentations and tutorials on how to use Spirit. This, time, I propose a presentation that will focus on the design and implementation of Spirit. But to add more to the thrill, I will present a major redesign of Spirit from the ground up, taking advantage of the new C++11 features. One important goal of this experimental version of Spirit (named X3) is to bring back the elegant simplicity of “Classic” Spirit, which was somehow lost with the complexity of Spirit-2 primarily due to the lack of important language features that are just starting to appear in C++ compilers. In this 90-minute presentation, I would like to get down and dirty with Modern C++11 code, and along the way, share my experience as well as expose some of C++11’s shortcomings and my wishes for C++1y.

Hope to see you there!

See you there!

It’s hard to pinpoint exactly the birthday of Spirit. Looking back, Spirit 1.0 which was uploaded to SourceForge in July 27, 2001 contains this comment in its main header file:

8/28/1999    Original Implementation [ run time polymorphic version ] (JDG)
4/30/2001    Template meta-programming implementation (JDG)
5/13/2001    Major redesign using iterators (JDG)
5/26/2001    Port to G++3.0 and BCC 5.5.1 thanks to Vladimir Prus
5/27/2001    Bug fixes in Difference and Xor classes (JDG)
5/30/2001    Added Iterators (JDG)

And then, there’s the original post to Boost developer’s list dated May 21, 2001:

Hello there,

Spirit is an object oriented recursive descent parser generator framework implemented using template meta-programming techniques. Expression templates allow us to approximate the syntax of Extended Backus Normal Form (EBNF) completely in C++. The Spirit framework enables a target grammar to be written exclusively in C++. EBNF grammar specifications can mix freely with other C++ code and, thanks to the generative power of C++ templates, are immediately executable. In retrospect, conventional compiler-compilers or parser-generators have to perform an additional translation step from the source EBNF code to C or C++ code.

The documentation and source code can be found at http://isis-tech.n3.net. I would appreciate feedback and comments.

Joel de Guzman

Let me declare that the July 27, 2001 SF upload should mark Spirit’s birthday. That’ll be 3 days from now.

Happy 10 years, Spirit!