why does this boost::spirit::qi rule not work? - c++

Question

I have a grammar that defines the following rules:
constantValue = qi::token(ID_FLOAT) | qi::token(ID_INTEGER);
postfixExpression = primaryExpression |
(postfixExpression >> qi::token(ID_OPENBRACKET) >> qi::token(ID_INTEGER) >> qi::token(ID_CLOSEBRACKET)) |
(postfixExpression >> qi::token(ID_DOT) >> qi::token(ID_IDENTIFIER));
primaryExpression = qi::token(ID_IDENTIFIER) |
constantValue |
(qi::token(ID_OPENPAREN) >> primaryExpression >> qi::token(ID_CLOSEPAREN));
ges = postfixExpression >> qi::eoi;
and I want it to match the following strings:
test[1]
testident.ident
and it should not match
test[1.2]
testident.5
but it fails to match the first 2 strings.
The lexer constructor is as follows:
custom_lexer()
: identifier("[a-zA-Z_][a-zA-Z0-9_]*")
, white_space("[ \\t\\n]+")
, integer_value("[1-9][0-9]*")
, hex_value("0[xX][0-9a-fA-F]+")
, float_value("[0-9]*\\.[0-9]+([eE][+-]?[0-9]+)?")
, float_value2("[0-9]+\\.([eE][+-]?[0-9]+)?")
, punctuator("&>|\\*\\*|\\*|\\+|-|~|!|\\/|%|<<|>>|<|>|<=|>=|==|!=|\\^|&|\\||\\^\\^|&&|\\|\\||\\?|:|,")// [ ] ( ) . &> ** * + - ~ ! / % << >> < > <= >= == != ^ & | ^^ && || ? : ,
{
using boost::spirit::lex::_start;
using boost::spirit::lex::_end;
this->self.add
(identifier, ID_IDENTIFIER)
/*(white_space, ID_WHITESPACE)*/
(integer_value, ID_INTEGER)
(hex_value, ID_INTEGER)
(float_value, ID_FLOAT)
(float_value2, ID_FLOAT)
("\\(", ID_OPENPAREN)
("\\)", ID_CLOSEPAREN)
("\\[", ID_OPENBRACKET)
("\\]", ID_CLOSEBRACKET)
("\\.", ID_DOT)
(punctuator, ID_PUNCTUATOR)
;
this->self("WS") = white_space;
}
Why don't I get a match for the mentioned strings?
Thank you
Tobias

Answer 1

I found the reason - I had to re-phrase the rule:
postfixExpression = primaryExpression >> *((qi::token(ID_OPENBRACKET) >> qi::token(ID_INTEGER) >> qi::token(ID_CLOSEBRACKET)) | (qi::token(ID_DOT) >> qi::token(ID_IDENTIFIER)));
I don't know why it's necessary, but now it seems to work.