boost::spirit, abstract syntax tree question
is there some trick to have an epsilon_p as a root_node?
(using ast_parse)
so id like this grammar to work:
Code:
expression_0
= expression_1 >> *(root_node_d[epsilon_p] >> expression_2) //!!! doesnt work
;
expression_1
= expression_2 >> *(
(root_node_d[ch_p('+')] >> expression_2) // works perfectly
(root_node_d[ch_p('-')] >> expression_2)
);
expression_2
= identifier
| value
| inner_node_d['(' >> expression_0 >> ')']
;
expression
= expression_0
;
unfortunately, there is no root node created for the rule expression_0.
so instead of building the abstract syntax tree for
"a b c d"
as
Code:
[]
/ \d
[]
/ \
[] c
/ \
a b
the tree is built as:
