/**
* Returns true if the linkage is connected when ignoring the links
* whose names are in the given list of link names.
* Actually, what it does is this: it returns false if the connectivity
* of the subgraph reachable from word 0 changes as a result of deleting
* these links.
*/
static bool
apply_must_form_a_cycle(PP_data *pp_data, Linkage sublinkage, pp_rule *rule)
{
List_o_links *lol;
size_t w;
for (w = 0; w < pp_data->num_words; w++)
{
for (lol = pp_data->word_links[w]; lol != NULL; lol = lol->next)
{
if (w > lol->word) continue; /* only consider each edge once */
if (!pp_linkset_match(rule->link_set, sublinkage->link_array[lol->link].link_name)) continue;
clear_visited(pp_data);
reachable_without_dfs(pp_data, sublinkage, w, lol->word, w);
if (!pp_data->visited[lol->word]) return false;
}
}
for (lol = pp_data->links_to_ignore; lol != NULL; lol = lol->next)
{
w = sublinkage->link_array[lol->link].lw;
/* (w, lol->word) are the left and right ends of the edge we're considering */
if (!pp_linkset_match(rule->link_set, sublinkage->link_array[lol->link].link_name)) continue;
clear_visited(pp_data);
reachable_without_dfs(pp_data, sublinkage, w, lol->word, w);
assert(lol->word < pp_data->num_words, "Bad word index");
if (!pp_data->visited[lol->word]) return false;
}
return true;
}
static int
apply_must_form_a_cycle(Postprocessor *pp,Sublinkage *sublinkage,pp_rule *rule)
{
/* Returns TRUE if the linkage is connected when ignoring the links
whose names are in the given list of link names.
Actually, what it does is this: it returns FALSE if the connectivity
of the subgraph reachable from word 0 changes as a result of deleting
these links. */
List_o_links *lol;
int w;
for (w=0; w<pp->pp_data.length; w++) {
for (lol = pp->pp_data.word_links[w]; lol != NULL; lol = lol->next) {
if (w > lol->word) continue; /* only consider each edge once */
if (!pp_linkset_match(rule->link_set, sublinkage->link[lol->link]->name)) continue;
memset(pp->visited, 0, pp->pp_data.length*(sizeof pp->visited[0]));
reachable_without_dfs(pp, sublinkage, w, lol->word, w);
if (!pp->visited[lol->word]) return FALSE;
}
}
for (lol = pp->pp_data.links_to_ignore; lol != NULL; lol = lol->next) {
w = sublinkage->link[lol->link]->l;
/* (w, lol->word) are the left and right ends of the edge we're considering */
if (!pp_linkset_match(rule->link_set, sublinkage->link[lol->link]->name)) continue;
memset(pp->visited, 0, pp->pp_data.length*(sizeof pp->visited[0]));
reachable_without_dfs(pp, sublinkage, w, lol->word, w);
if (!pp->visited[lol->word]) return FALSE;
}
return TRUE;
}
static void reachable_without_dfs(Postprocessor *pp, Sublinkage *sublinkage, int a, int b, int w) {
/* This is a depth first search of words reachable from w, excluding any direct edge
between word a and word b. */
List_o_links *lol;
pp->visited[w] = TRUE;
for (lol = pp->pp_data.word_links[w]; lol != NULL; lol = lol->next) {
if (!pp->visited[lol->word] && !(w == a && lol->word == b) && ! (w == b && lol->word == a)) {
reachable_without_dfs(pp, sublinkage, a, b, lol->word);
}
}
}
/**
* For each link in the linkage that is in the must_form_a_cycle list,
* we want to make sure that that link is in a cycle. We do this
* simply by deleting the link, then seeing if the end points of that
* link are still connected.
*/
static void reachable_without_dfs(PP_data *pp_data,
Linkage sublinkage, size_t a, size_t b, size_t w)
{
/* This is a depth first search of words reachable from w, excluding
* any direct edge between word a and word b. */
List_o_links *lol;
assert(w < pp_data->num_words, "Bad word index");
pp_data->visited[w] = true;
for (lol = pp_data->word_links[w]; lol != NULL; lol = lol->next)
{
assert(lol->word < pp_data->num_words, "Bad word index");
if (!pp_data->visited[lol->word] &&
!(w == a && lol->word == b) &&
!(w == b && lol->word == a))
{
reachable_without_dfs(pp_data, sublinkage, a, b, lol->word);
}
}
}