boost-spirit-x3

After reading the the Spirit X3 tutorial on error handling and some experimentation. I was drawn to a conclusion. I believe there is some room for improvement on the topic of error handing in X3. An important goal from my perspective is to provide a meaningful error message. First and foremost adding a semantic action that will set the _pass(ctx) member to false wouldn’t do it because X3 will try to match something else. Only throwing an x3::expectation_failure will quit the parse function prematurely, i.e. without trying to match anything else. So what is left are the parser directive expect

In my my previous question it was suggested that the performance of my boost::spirit::x3 parser could be improved by parsing into a boost::string_view using the raw directive. However, I have difficulties getting it to compile. This is what I found out: Before x3 , one had to specialize assign_to_attribute_from_iterators (see e.g. this SO answer ) to handle the raw directive. x3 now uses the move_to free function instead (see e.g. this SO answer ). I therefore added a move_to overload which works if I parse from char* : #include <iostream> #include <string> #include <boost/utility/string_view

How does one prevent X3 symbol parsers from matching partial tokens? In the example below, I want to match "foo", but not "foobar". I tried throwing the symbol parser in a lexeme directive as one would for an identifier, but then nothing matches. Thanks for any insights! #include <string> #include <iostream> #include <iomanip> #include <boost/spirit/home/x3.hpp> int main() { boost::spirit::x3::symbols<int> sym; sym.add("foo", 1); for (std::string const input : { "foo", "foobar", "barfoo" }) { using namespace boost::spirit::x3; std::cout << "\nParsing " << std::left << std::setw(20) << ("'" +

Using Boost.Spirit X3 , I want to parse a comma-separated list of ranges and individual numbers (e.g. 1-4, 6, 7, 9-12) into a single std::vector<int> . Here's what I've come up with: namespace ast { struct range { int first_, last_; }; using expr = std::vector<int>; } namespace parser { template<typename T> auto as_rule = [](auto p) { return x3::rule<struct _, T>{} = x3::as_parser(p); }; auto const push = [](auto& ctx) { x3::_val(ctx).push_back(x3::_attr(ctx)); }; auto const expand = [](auto& ctx) { for (auto i = x3::_attr(ctx).first_; i <= x3::_attr(ctx).last_; ++i) x3::_val(ctx).push_back(i)

Is there a document somewhere which describes how various spirit::x3 rule definition operations affect attribute compatibility? I was surprised when: x3::lexeme[ x3::alpha > *(x3::alnum | x3::char_('_')) ] could not be moved into a fusion-adapted struct: struct Name { std::string value; }; For the time being, I got rid of the first mandatory alphabetical character, but I would still like to express a rule which defines that the name string must begin with a letter. Is this one of those situations where I need to try adding eps around until it works, or is there a stated reason why the above

From the Boost Spirit X3 tutorial: First, let's create a struct representing an employee: namespace client { namespace ast { struct employee { int age; std::string surname; std::string forename; double salary; }; }} Then, we need to tell Boost.Fusion about our employee struct to make it a first-class fusion citizen that the grammar can utilize. BOOST_FUSION_ADAPT_STRUCT( client::ast::employee, (int, age) (std::string, surname) (std::string, forename) (double, salary) )` [...] In fusion's view, a struct is just a form of a tuple. You can adapt any struct to be a fully conforming fusion tuple. [

I've written the following recursive rule in boost::spirit::x3 but it only seems to compile in g++/clang, not VS2017 (15.5.3): #include <iostream> #include <boost/spirit/home/x3.hpp> namespace lex3 { namespace x3 = boost::spirit::x3; x3::rule<struct foo_class> const foo = "foo"; x3::rule<struct bar_class> const bar = "bar"; auto bar_def = *((x3::char_ - "/*") - "*/") >> *(foo > *((x3::char_ - "/*") - "*/")); auto foo_def = "/*" > bar > "*/"; BOOST_SPIRIT_DEFINE(foo) BOOST_SPIRIT_DEFINE(bar) } int main(int argc, char** argv) { std::string input = "/* a /* nested */ comment */"; auto f = input