On 13-05-30 08:35 AM, Simon wrote:
Hi, For one part of a large project, I need to parse math and turn the "mathematical objects" into a C++ abstraction of them. Is it possible that a nested pattern hold semantic values within itself and can be queried for that value somehow? As if a match were a function of its sub-patterns' matches, if that makes sense...
Code might speak better than my english:
class math_number {...}; class math_addition {...}; class math_arglist {...}; class math_funcdef {...};
sregex integer = (s1= +_d) [ return math_number( as<int>(s1) ) ];
sregex addition = (s1= integer) >> '+' >> (s2= integer) [ return math_addition( as<math_number>(s1), as<math_number>(s2) ) ];
sregex arglist = (s1= identifier) >> *( ',' >> (s2= arglist)) [ std::vector<math_id> ids( as<math_arglist>(s2).begin(), as<math_arglist>(s2).end() ); ids.push_back(as<math_id>(s1)); return ids; ]
sregex funcdef = ((s1= identifier) >> '(' >> (s2= arglist) >> ")=" >> (s3= addition)) [ return math_funcdef( as<math_id>(s1), as<math_arglist>(s2), as<math_addition>(s3) ) ];
I just want to avoid the funcdef above to be responsible for the construction of the various math_* objects the funcdef will hold (some of which will be complex to construct). And if I really must store the objects in an external stack, how should the parent-objects find their child-objects?
It really sounds to me that this problem would be better addressed by Boost.Spirit and its attributed parsers. -- Eric Niebler Boost.org