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.
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.
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Tagged with: MultiPass • 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?”.
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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.
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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.
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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’.
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Tagged with: Qi
Nov 20
Several people have been asking the question of how it would be possible to access the current iterator position from a semantic action. Different solutions have been proposed, all of them somehow abusing the predefined Qi directive raw[] which normally exposes as its attribute the pair of iterators pointing to the range in the input stream matched by the embedded parser. I thought this to be a nice incentive to write about how you can create your own parser components.
See full article here.
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Tagged with: Qi
Nov 17
Wanna make a blazingly fast rule? Use BOOST_AUTO! Check it out here. The code defines a named rule using C++0x auto when available and falls back to some template wizardry on older compilers.
See full article here.
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Tagged with: Qi
Nov 17
This sample is a port of the original “Nabialek trick” from classic Spirit.
See full article here.
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Tagged with: Qi
Nov 15
One of the goals of this blog is to provide shrink wrapped solutions for small everyday parsing and output generation problems. We hope to show how Spirit may be used to simplify the life for you as a C++ programmer related to data conversion problems from some external representation to your internal data structures and vice versa.
See full article here.
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