Is it a boost spirit regression? - boost

Question

I have a boost spirit parser which works very well with boost 1.46.1, and which doesn't work with boost 1.54.
This parser extract informations from the following sentence, which is a variable initialization in a DSEL : "Position #start=0;0;0".
Informations extracted from this sentence are stored in a structure :
Type of the variable will be stored (here position) ;
Name of variable (here start) ;
The "#" means that the variable is "static" ;
The value of the variable (0;0;0).
The code to extract these inforamtions is as follow :
#include <iostream>
#include <boost/spirit/include/classic.hpp>
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
#include <boost/spirit/include/qi_char_class.hpp>
using namespace std;
using namespace boost::spirit;
struct VariableInitialization
{
std::string m_type;
bool m_is_static;
std::string m_name;
std::string m_value;
};
BOOST_FUSION_ADAPT_STRUCT(
VariableInitialization,
(std::string, m_type)
(bool, m_is_static)
(std::string, m_name)
(std::string, m_value)
)
template <typename Iterator>
struct VariableInitializationParser : qi::grammar<Iterator, VariableInitialization(), ascii::space_type> {
/*!
* IsStatic is a mapping betwen a char and a boolean
*/
struct IsStatic_ : qi::symbols<char, bool> {
IsStatic_()
{
add("#", false)("#", true);
}
}IsStatic;
VariableInitializationParser() :
VariableInitializationParser::base_type(start) {
using qi::lit;
using ascii::char_;
using qi::_val;
using qi::_1;
/*!
* For now, type is one of the three following litterals :
*/
var_type %= lit("Position")|lit("String")|lit("Numeric")|lit("Integer")|lit("Trajectory");
/*!
* identifier is how a variable can be named. Name of variable is an alpha (a-zA-Z) or an _,followed
* by any alpha numeric (a-zA-Z0-9) or a _. The followings are correct :
* _toto _T5ot_To t1oTo ...
* The following are incorrect
* 12toto -tiotp ...
*/
identifier %= ((ascii::alpha|char_('_')) >> *(ascii::alnum|char_('_')));
/*!
* var value can be anything because it's parsed by someone else.
*/
var_value %= qi::lexeme[*(char_)];
start = var_type >> IsStatic >> identifier >> '=' >> var_value;
}
qi::rule<Iterator, std::string(), ascii::space_type> var_type;
qi::rule<Iterator, std::string(), ascii::space_type> identifier;
qi::rule<Iterator, std::string(), ascii::space_type> var_value;
qi::rule<Iterator, VariableInitialization(), ascii::space_type> start;
};
int main()
{
VariableInitialization variable;
std::string input = "Position #toto=1;2;2";
std::string::const_iterator iter = input.begin();
std::string::const_iterator end = input.end();
// The phrase_parse call wil fill the structure "variable" with the good values if the syntax is correct.
// if the syntax is not correct, the method will return false.
// So if input = "Integer #toto= 6", variable.m_type == "Integer", variable.m_isStatic==true,
// variable.m_name=="toto" and variable.m_vale="6".
VariableInitializationParser<std::string::const_iterator> m_parser;
bool ok = phrase_parse(iter, end, m_parser, boost::spirit::ascii::space, variable);
if(!ok) return false;
std::cout << "Boost version : " << BOOST_VERSION << std::endl;
std::cout << "Type : " << variable.m_type << std::endl
<< "Is Static : " << variable.m_is_static << std::endl
<< "Name :" << variable.m_name << std::endl
<< "Value :" << variable.m_value << std::endl;
return 0;
}
Output of the following code is different in Boost 1.46.1 and in boost 1.53.
With boost 1.46.1 I have the following Output :
Boost version : 104601
Type : Position
Is Static : 1
Name :toto
Value :1;2;2
With boost 1.54 I have :
Boost version : 105400
Type :
Is Static : 1
Name :toto
Value :1;2;2
As you can see in boost 1.54 the Position output is not filled by the parser.
I read (maybe not carefully) the changelog of Fusion and Spirit, and I can't find why this happens.
Does someone have an explaination ?

Answer 1

No this is not a regression. Quite clearly you depended on undocumented (possibly undefined) behaviour.
Just change lit into string, or just slightly more compact:
var_type = qi::raw[lit("Position")|"String"|"Numeric"|"Integer"|"Trajectory"];
See it Live On Coliru
#include <iostream>
#include <boost/spirit/include/qi.hpp>
#include <boost/fusion/include/adapt_struct.hpp>
using namespace std;
using namespace boost::spirit;
struct VariableInitialization
{
std::string m_type;
bool m_is_static;
std::string m_name;
std::string m_value;
};
BOOST_FUSION_ADAPT_STRUCT(
VariableInitialization,
(std::string, m_type)
(bool, m_is_static)
(std::string, m_name)
(std::string, m_value)
)
template <typename Iterator>
struct VariableInitializationParser : qi::grammar<Iterator, VariableInitialization(), ascii::space_type> {
struct IsStatic_ : qi::symbols<char, bool> {
IsStatic_() {
add("#", false)("#", true);
}
} IsStatic;
VariableInitializationParser() :
VariableInitializationParser::base_type(start) {
using qi::lit;
using ascii::char_;
var_type = qi::raw[lit("Position")|"String"|"Numeric"|"Integer"|"Trajectory"];
identifier = (ascii::alpha|'_') >> *(ascii::alnum|'_');
var_value = qi::lexeme[*(char_)];
start = var_type >> IsStatic >> identifier >> '=' >> var_value;
}
qi::rule<Iterator, std::string(), ascii::space_type> var_type;
qi::rule<Iterator, std::string(), ascii::space_type> identifier;
qi::rule<Iterator, std::string(), ascii::space_type> var_value;
qi::rule<Iterator, VariableInitialization(), ascii::space_type> start;
};
int main()
{
VariableInitialization variable;
std::string input = "Position #toto=1;2;2";
std::string::const_iterator iter = input.begin();
std::string::const_iterator end = input.end();
VariableInitializationParser<std::string::const_iterator> m_parser;
bool ok = phrase_parse(iter, end, m_parser, boost::spirit::ascii::space, variable);
if(!ok) return false;
std::cout << "Boost version : " << BOOST_VERSION << "\n";
std::cout << "Type : " << variable.m_type << "\n"
<< "Is Static : " << variable.m_is_static << "\n"
<< "Name :" << variable.m_name << "\n"
<< "Value :" << variable.m_value << "\n";
}