boost-spirit-qi

Looking at this example for implementing a Spirit parser, something caught me out when I was trying to write something similar. The attribute template parameter of the grammar ( std::map<std::string, std::string>() ) and the signature template parameter of the rules (e.g. qi::rule<Iterator, std::string()> key, value ) contain parentheses. namespace qi = boost::spirit::qi; template <typename Iterator> struct keys_and_values : qi::grammar<Iterator, std::map<std::string, std::string>()> // <- parentheses here { keys_and_values() : keys_and_values::base_type(query) { query = pair >> *((qi::lit(';'

I wanted to raise a subject that just sent me down a rabbit hole and brought up a question about qi::symbols. It all started while I was looking into the new beast library and read a tutorial example It starts with a function that guesses mime types from http path extensions. I started to look more closely and saw this: auto const ext = [&path] { auto const pos = path.rfind("."); if(pos == boost::beast::string_view::npos) return boost::beast::string_view{}; return path.substr(pos); }(); It took me a while to figure out it was a IIFE in C++ style, and was used to initialize ext while declaring

When trying to parse text into a boost::variant, the variant's value does not get changed. The parsers by themselves appear to work fine, so my assumption is that I'm doing something wrong with the variant code. I'm using boost 1.46.1 and the following code compiles in Visual Studio 2008. 1st Update hkaiser noted that the rule and grammar template arguments must not be Variant but Variant() . This got a bit "further" as I now have a compilation error in boost_1_46_1\boost\variant\variant.hpp(1304) . The comment says: // NOTE TO USER : // Compile error here indicates that the given type is not

I'm writing a lexigraphical analyser. It takes an English string, and converts it into a set of latitude/longitude co-ordinates. It's a bit like Google Earth. Anyway, I've written my symbol tables and grammar, and it's happily parsing formatted data. struct LatLongDegrees { std::string dirLat_; double degLat_; std::string dirLong_; double degLong_; } For example: {"North", 23.59, "East", -30.82} Here is my grammar: basic =(latitude >> ' ' >> double_ >> ' ' >> longitude >> ' ' >> double_); Where latitude and longitude are symbol tables that map from shorthand compass directions to strings (eg

I want to parse a file that looks like this (FASTA-like text format): >InfoHeader "Some text sequence that has a line break after every 80 characters" >InfoHeader "Some text sequence that has a line break after every 80 characters" ... e.g.: >gi|31563518|ref|NP_852610.1| microtubule-associated proteins 1A/1B light chain 3A isoform b [Homo sapiens] MKMRFFSSPCGKAAVDPADRCKEVQQIRDQHPSKIPVIIERYKGEKQLPVLDKTKFLVPDHVNMSELVKI IRRRLQLNPTQAFFLLVNQHSMVSVSTPIADIYEQEKDEDGFLYMVYASQETFGFIRENE I wrote a parser for this with boost::spirit. The parser correctly stores the header line and the following text