<<
#include <stdlib.h>
#include <string.h>
size_t mylexfn(p_context_t * context, p_token_info_t * out_token_info);
>>

ptype int;

lex_fn mylexfn;

drop /\s+/;
token lparen /\(/;
token rparen /\)/;
token plus /\+/;
token num /\d+/ << char b[32]; memcpy(b, match, match_length); b[match_length] = '\0'; $$ = atoi(b); >>

Start -> Expr << $$ = $1; >>
Expr -> num << $$ = $1; >>
Expr -> Expr plus num << $$ = $1 + $3; >>