// Computes N_1+( * ab * )
uint64_t N1PlusFrontBack(const node_type& node, const node_type& node_rev,
pattern_iterator pattern_begin, pattern_iterator pattern_end) const
{
auto timer = lm_bench::bench(timer_type::N1PlusFrontBack);
// ASSUMPTION: lb, rb already identify the suffix array range corresponding to 'pattern' in
// the forward tree
// ASSUMPTION: pattern_begin, pattern_end cover just the pattern we're interested in (i.e.,
// we want N1+ dot pattern dot)
uint64_t pattern_size = std::distance(pattern_begin, pattern_end);
uint64_t back_N1plus_front = 0;
// this is when the pattern matches a full edge in the CST
if (!m_cst.is_leaf(node) && pattern_size == m_cst.depth(node)) {
if (*pattern_begin == PAT_START_SYM) {
return m_cst.degree(node);
}
auto w = m_cst.select_child(node, 1);
auto root_id = m_cst.id(m_cst.root());
std::vector<uint64_t> new_pattern(pattern_begin, pattern_end);
new_pattern.push_back(EOS_SYM);
while (m_cst.id(w) != root_id) {
auto lb_rev_stored = m_cst_rev.lb(node_rev);
auto rb_rev_stored = m_cst_rev.rb(node_rev);
uint64_t symbol = m_cst.edge(w, pattern_size + 1);
assert(symbol != EOS_SYM);
new_pattern.back() = symbol;
// find the symbol to the right
// (which is first in the reverse order)
backward_search_wrapper(m_cst_rev.csa, lb_rev_stored, rb_rev_stored, symbol, lb_rev_stored,
rb_rev_stored);
back_N1plus_front += N1PlusBack(m_cst_rev.node(lb_rev_stored, rb_rev_stored),
new_pattern.begin(), new_pattern.end());
w = m_cst.sibling(w);
}
return back_N1plus_front;
} else {
// special case, only one way of extending this pattern to the right
if (*pattern_begin == PAT_START_SYM && *(pattern_end - 1) == PAT_END_SYM) {
/* pattern must be 13xyz41 -> #P(*3xyz4*) == 0 */
return 0;
} else if (*pattern_begin == PAT_START_SYM) {
/* pattern must be 13xyzA -> #P(*3xyz*) == 1 */
return 1;
} else {
/* pattern must be *xyzA -> #P(*xyz*) == N1PlusBack */
return N1PlusBack(node_rev, pattern_begin, pattern_end);
}
}
}
iterator_type& operator++()
{
m_cur_node = m_cst->sibling(m_cur_node);
return *this;
}
