+ | symbol T_LESS symbol { $$ = expr_alloc_comp(E_LTH, $1, $3); }
+ | symbol T_LESS_EQUAL symbol { $$ = expr_alloc_comp(E_LEQ, $1, $3); }
+ | symbol T_GREATER symbol { $$ = expr_alloc_comp(E_GTH, $1, $3); }
+ | symbol T_GREATER_EQUAL symbol { $$ = expr_alloc_comp(E_GEQ, $1, $3); }