Welcome to Spirit
Spirit is a set of C++ libraries for parsing and output generation
implemented as Domain Specific Embedded Languages (DSEL) using Expression templates and Template Meta-Programming. The Spirit libraries enable a
target grammar to be written exclusively in C++. Inline grammar
specifications can mix freely with other C++ code and, thanks to the
generative power of C++ templates, are immediately executable.
Spirit is part of Boost Libraries, a
peer-reviewed, open collaborative development effort.
May 13
Michael Caisse (of Object Modeling Designs), some of you will know him from the Freenode #boost IRC channel, presented his talk about Spirit at BoostCon 2010 last Tuesday. I personally very much like listening to his knowledgeable and entertaining presentations. Apparently many people do so as well, the room he presented in was overfull. People even sat on the floor as all seats were taken. So in case you are interested – here is a link to his slides: Using Spirit V2: Qi and Karma.
GD Star Rating
loading...
Tagged with: Karma • Qi
May 11
Finally, yesterday was the day! Joel and I presented the current status of our work related to the ‘Writing a Compiler’ effort. We submitted this talk to BoostCon 2010 and got accepted back in January. Having to present at BoostCon just put a nice pressure onto us to get moving and to start working on the project. I don’t want to go into any detail about the presentation itself. This will be done in future articles to be published after BoostCon. I just wanted to provide a link to the slides for those interested in having a look. Ok, here we go: A Framework for RAD Spirit, grab it while it’s hot!
GD Star Rating
loading...
Tagged with: Karma • Qi
May 08
Finally, the long wait and the preparations for BoostCon 2010 are over. The last weeks were dominated by writing the code and creating the slides for our talk ‘A Framework for RAD Spirit‘. Regular readers of this site probably have already wondered why we have been inactive here since mid-March. Well, that is mainly because of preparing for BoostCon turned out to be too time consuming to leave any room for writing posts and articles.
Continue reading »
GD Star Rating
loading...
Tagged with: Karma • Qi
Mar 05
The following article is about tracking the parsing position with Spirit V2. This is useful for generating error messages which tell the user exactly where an error has occurred. We also show how to use Spirit V2 to parse from an input stream without first reading the whole stream into a std::string.
Continue reading »
GD Star Rating
loading...
Tagged with: MultiPass • Qi
Mar 03
The concept of Spirit’s semantic actions seems to be easy enough to understand as most people new to the library prefer their usage over applying the built-in attribute propagation rules. That is not surprising. The idea of attaching a function to any point of a grammar which is called whenever the corresponding parser matched is straighforward to grasp. Earlier versions of Spirit required a semantic action to conform to a very specific interface. Today’s semantic actions are more flexible and more powerful. Recently, a couple of people asked questions about them. So I decided dedicating this Tip of the Day to the specifics and the usage model of semantic actions in Spirit Qi.
Continue reading »
GD Star Rating
loading...
Tagged with: Karma • Qi
Feb 24
Spirit supports skipper based parsing since its very invention. So this is definitely not something new to Spirit V2. Nevertheless, the recent discussion on the Spirit mailing list around the semantics of Qi’s lexeme[] directive shows the need for some clarification. Today I try to answer questions like: “What does it mean to use a skipper while parsing?”, or “When do I want to use a skipper and when not?”.
Continue reading »
GD Star Rating
loading...
Tagged with: Qi
Feb 17
Recently, there have been a couple of questions on the Spirit mailing list asking how to parse as set of things known in advance in any sequence and any combination. A simple example would be a list of key/value pairs with known keys but the keys may be ordered in any sequence. This use case seems to be quite common. Fortunately Spirit provides you with a predefined parser component designed for exactly that purpose: the permutation parser.
Continue reading »
GD Star Rating
loading...
Tagged with: Qi
Feb 08
Here is another question raised from time to time: “I know how to use a plain struct as an attribute for a sequence parser in Qi by adapting it with BOOST_FUSION_ADAPT_STRUCT. Unfortunately this does not work if the struct is a template. What can I do in this case?”.
There have been plans for a while to create a separate Fusion facility BOOST_FUSION_ADAPT_TPL_STRUCT allowing to adapt templated data types, but this is not in place yet. Today I will describe a trick you can apply to adapt your templates into ‘proper’ Fusion sequences anyway.
Continue reading »
GD Star Rating
loading...
Tagged with: Qi
Jan 31
Most questions on the main Spirit mailing list are centered around attributes and how to correctly utilize Spirit’s attribute propagation rules. We discussed the related basics in several posts already, but many people still have problems to understand the rules. Somebody recently asked on the mailing list whether it would be possible to print the attribute type exposed by an arbitrary parser expression. I answered by posting a sketchy code snippet (see here), but afterwards I realized it might be a good topic for yet another ‘Tip of the Day’.
Continue reading »
GD Star Rating
loading...
Tagged with: Qi
Jan 28
After writing about local variables for rules here I would like to get back to some information I have had lying around for some time already. Today’s topic seems to be a nice fit as porting the dynamic parsers from Spirit.Classic requires to utilize local variables. This allows me to give you some more examples for this facility.
Previous versions of Spirit, which are the versions we refer to as Spirit.Classic today, implemented special dynamic parsers allowing to insert control statements into the parsing process (such as if_p, while_p, and for_p). These dynamic parsers are not available anymore in Qi. But it is easy enough to achieve the same behavior using existing Qi components. This ‘Tip of the Day’ describes those techniques, which have been developed and contributed by Carl Barron. Thanks Carl!
Continue reading »
GD Star Rating
loading...
Tagged with: Qi
Jan 21
In the previous installment of the ‘Tip of the Day’ I started to talk about some lesser known features related to semantic actions. Today I will highlight some more details. If a semantic action is attached to a component which is part of an expression assigned to a rule (the rule’s right hand side) it is not only possible to access the attributes of the components it is connected with. In addition it is possible to access rule specific values! Sounds interesting? Read on!
Continue reading »
GD Star Rating
loading...
Tagged with: Karma • Qi
Jan 19
The concept of semantic actions seems to be quite easy to understand. It appears to be at least easier to grasp than the concept of attribute propagation. This might be because semantic actions have been part of Spirit for almost a decade now. Additionally, with semantic actions data flow control is tightly connected to the component the semantic action is attached to, so the effect is highly localized and easy to spot.
Spirit has some new features related to semantics actions. That’s reason enough to talk about how attributes can be accessed from inside semantic actions.
Continue reading »
GD Star Rating
loading...
Tagged with: Karma • Qi
Jan 17
The Freenet #boost IRC channel amazes me every day with the amount of interest Spirit is getting from a lot of people. Thanks to everyone over there! But the best is those people are asking many interesting questions allowing me to come up with yet another Tip of the Day.
Today’s question has been asked by @psicode: “What is the difference between the components created by the unary operators ‘!’ and ‘~’?”. As the semantics of those operators are slightly dissimilar in Qi and Karma, I will talk about them separately. I will write about the Qi operators today and about the corresponding Karma operators in one of the next installments.
Continue reading »
GD Star Rating
loading...
Tagged with: Qi
Jan 15
If you read the article about attribute handling for non-terminals (The Magical Power of Attributes in Spirit – Directives and Non-terminals) you might remember that Spirit’s non-terminals (rules and grammars) are somewhat special with regard to their attribute handling. In today’s ‘Tip of the Day’ I would like to revisit this topic as it still seems to be difficult to understand.
Continue reading »
GD Star Rating
loading...
Tagged with: Karma • Qi
Jan 14
Over at the Freenet #boost IRC channel somebody (I think it was @VeXocide) suggested to write a ‘Tip of the Day’ about the Qi directive raw[]. I was told this ‘was a major stumbling stone’ while learning Qi. I always appreciate to get suggestions for articles, so here we go…
Continue reading »
GD Star Rating
loading...
Tagged with: Qi
Recent Comments