jefftrull’s gists

jefftrull / gist:983d783cf508249e5352de8e844a27cb

Created September 20, 2016 05:36

Interesting (possibly wrong) synthesized attribute behavior

	#include <iostream>
	#include <boost/spirit/include/qi.hpp>
	#include <boost/optional.hpp>
	#include <boost/optional/optional_io.hpp>

	int main() {
	using namespace std;

	// parsing parentheses that may or may not contain integers
	string in("(10) () (20)");

jefftrull / gist:0d7ecfef151c39885a7633d7547df8e6

Created April 18, 2016 16:06

*qi::string is compatible with both std::string (concatenation) and std::vector<std::string> (push_back) attributes

	#include <string>
	#include <vector>

	#include <boost/spirit/include/qi.hpp>
	using string_it_t = std::string::const_iterator;

	int main() {
	using namespace boost::spirit;
	using namespace boost::spirit::qi;

jefftrull / gist:2fbbd52a0dec25c1e14d1e69af3361ac

Created April 18, 2016 03:21

Spirit sequence-of-sequences: struct vs. string

	// To see if a rule whose attribute is sequence-of-sequence can make appends happen somehow

	#include <string>
	#include <vector>

	#include <boost/spirit/include/qi.hpp>
	#include <boost/fusion/include/adapt_struct.hpp>

	struct tiny {
	std::string thing;

jefftrull / test_ub.cpp

Created March 5, 2016 00:14

Simple test of signed overflow UB

	#include <iostream>
	#include <cstdint>
	#include <limits>

	int main(int argc, char **argv) {
	std::int32_t i = std::numeric_limits<int32_t>::max();
	i++; // signed overflow
	if (i < 0) {
	std::cerr << "i<0 and i=" << i << "\n"; // "expected" or "safe" result (-O1)
	} else {

jefftrull / as_string.cpp

Created May 18, 2015 19:58

Demonstration of apparent need for as_string when synthesizing a sequence of characters to a std::string

	#include <string>
	#include <iostream>
	#include <sstream>

	#define BOOST_SPIRIT_USE_PHOENIX_V3
	#include <boost/spirit/include/qi.hpp>
	#include <boost/spirit/include/phoenix.hpp>

	int main() {

jefftrull / gist:928eac7d47e61f5d9634

Created April 11, 2015 21:09

Demonstration of using a Qi symbol table with a Lex-based Spirit parser, case-insensitive

	#include <string>

	#include <boost/spirit/include/lex_lexertl.hpp>
	#include <boost/spirit/include/lex_lexertl_position_token.hpp>
	#include <boost/spirit/include/support_istream_iterator.hpp>

	#include <boost/spirit/include/qi.hpp>
	#include <boost/spirit/include/phoenix.hpp>

	#include <boost/algorithm/string/case_conv.hpp>

jefftrull / gist:40a441bdb75365b2bf75

Last active August 29, 2015 14:18

An attempt to construct a functional-style function value-returning function from a mutating function, using Phoenix

	// test transforming a mutating function into a value-returning function via Phoenix
	// i.e., void f(T& a) -> T f(T const& a) or T F(T a)

	#define BOOST_SPIRIT_USE_PHOENIX_V3

	#include <iostream>
	#include <string>
	#include <boost/spirit/include/phoenix.hpp>
	#include <boost/algorithm/string/case_conv.hpp>

jefftrull / gist:25fba71dae683bc48f74

Created February 17, 2015 06:58

Demo of getting a dense vector from a row of a sparse matrix in Eigen

	#include <iostream>
	#include <vector>
	#include <Eigen/Dense>
	#include <Eigen/Sparse>

	int main() {
	using namespace std;
	using namespace Eigen;

	vector<Triplet<double> > tripletList;

jefftrull / gist:561b4e51d03bb3df3f86

Created December 4, 2014 10:30

attempt to partially specialize class by defining a member function template to be different for a certain *class* template parameters

	#include <typeinfo>
	#include <string>

	#include <iostream>
	template<typename T> struct A {
	template<typename U>
	A(U u) {
	std::cout << std::string("class template parameter generic, ctor template parameter ") + typeid(u).name() << std::endl;
	}
	};

jefftrull / gist:131626a0dc13238510c2

Created December 3, 2014 18:45

demo "partial" specialization of a class template with a member function template

	#include <typeinfo>
	#include <string>

	#include <iostream>
	template<typename T> struct A {
	template<typename U>
	void foo(U u) {
	std::cout << std::string("class template parameter generic, function template parameter ") + typeid(u).name() << std::endl;
	}
	};

Jeff Trull jefftrull