/**
* psuedocount is used to check to see if a parse is even possible,
* so that we don't waste cpu time performing an actual count, only
* to discover that it is zero.
*
* Returns false if and only if this entry is in the hash table
* with a count value of 0. If an entry is not in the hash table,
* we have to assume the worst case: that the count might be non-zero,
* and since we don't know, we return true. However, if the entry is
* in the hash table, and its zero, then we know, for sure, that the
* count is zero.
*/
static bool pseudocount(count_context_t * ctxt,
int lw, int rw, Connector *le, Connector *re,
unsigned int null_count)
{
Count_bin * count = table_lookup(ctxt, lw, rw, le, re, null_count);
if (NULL == count) return true;
if (hist_total(count) == 0) return false;
return true;
}
/**
* returns NULL if there are no ways to parse, or returns a pointer
* to a set structure representing all the ways to parse.
*
* This code is similar to do_count() in count.c -- for a good reason:
* the do_count() function did a full parse, but didn't actually
* allocate an memory structures to hold the parse. This also does
* a full parse, but it also allocates and fills out the various
* parse structures.
*/
static
Parse_set * mk_parse_set(Sentence sent, fast_matcher_t *mchxt,
count_context_t * ctxt,
Disjunct *ld, Disjunct *rd, int lw, int rw,
Connector *le, Connector *re, unsigned int null_count,
bool islands_ok, Parse_info pi)
{
int start_word, end_word, w;
X_table_connector *xt;
Count_bin * count;
assert(null_count < 0x7fff, "mk_parse_set() called with null_count < 0.");
count = table_lookup(ctxt, lw, rw, le, re, null_count);
/* If there's no counter, then there's no way to parse. */
if (NULL == count) return NULL;
if (hist_total(count) == 0) return NULL;
xt = x_table_pointer(lw, rw, le, re, null_count, pi);
/* Perhaps we've already computed it; if so, return it. */
if (xt != NULL) return &xt->set;
/* Start it out with the empty set of parse chocies. */
/* This entry must be updated before we return. */
xt = x_table_store(lw, rw, le, re, null_count, pi);
/* The count we previously computed; its non-zero. */
xt->set.count = hist_total(count);
#define NUM_PARSES 4
// xt->set.cost_cutoff = hist_cost_cutoff(count, NUM_PARSES);
// xt->set.cut_count = hist_cut_total(count, NUM_PARSES);
#define RECOUNT(X) /* Make it disappear... */
RECOUNT({xt->set.recount = 1;})
/* If the two words are next to each other, the count == 1 */
if (lw + 1 == rw) return &xt->set;
/** Misnamed, this has nothing to do with chart parsing */
static void chart_parse(Sentence sent, Parse_Options opts)
{
int nl;
fast_matcher_t * mchxt;
count_context_t * ctxt;
/* Build lists of disjuncts */
prepare_to_parse(sent, opts);
if (resources_exhausted(opts->resources)) return;
mchxt = alloc_fast_matcher(sent);
ctxt = alloc_count_context(sent->length);
print_time(opts, "Initialized fast matcher");
if (resources_exhausted(opts->resources))
{
free_count_context(ctxt);
free_fast_matcher(mchxt);
return;
}
/* A parse set may have been already been built for this sentence,
* if it was previously parsed. If so we free it up before
* building another. Huh ?? How could that happen? */
free_parse_info(sent->parse_info);
sent->parse_info = parse_info_new(sent->length);
nl = opts->min_null_count;
while (true)
{
Count_bin hist;
s64 total;
if (resources_exhausted(opts->resources)) break;
sent->null_count = nl;
hist = do_parse(sent, mchxt, ctxt, sent->null_count, opts);
total = hist_total(&hist);
if (opts->verbosity > 1)
{
prt_error("Info: Total count with %zu null links: %lld\n",
sent->null_count, total);
}
/* total is 64-bit, num_linkages_found is 32-bit. Clamp */
total = (total > INT_MAX) ? INT_MAX : total;
total = (total < 0) ? INT_MAX : total;
sent->num_linkages_found = (int) total;
print_time(opts, "Counted parses");
select_linkages(sent, mchxt, ctxt, opts);
compute_chosen_disjuncts(sent);
sane_morphism(sent, opts);
post_process_linkages(sent, opts);
if (sent->num_valid_linkages > 0) break;
/* If we are here, then no valid linkages were found.
* If there was a parse overflow, give up now. */
if (PARSE_NUM_OVERFLOW < total) break;
/* loop termination */
if (nl == opts->max_null_count) break;
/* If we are here, we are going round again. Free stuff. */
free_linkages(sent);
nl++;
}
sort_linkages(sent, opts);
free_count_context(ctxt);
free_fast_matcher(mchxt);
}
static Count_bin do_count(fast_matcher_t *mchxt,
count_context_t *ctxt,
int lw, int rw,
Connector *le, Connector *re,
int null_count)
{
Count_bin zero = hist_zero();
Count_bin total;
int start_word, end_word, w;
Table_connector *t;
assert (0 <= null_count, "Bad null count");
t = find_table_pointer(ctxt, lw, rw, le, re, null_count);
if (t) return t->count;
/* Create the table entry with a tentative null count of 0.
* This count must be updated before we return. */
t = table_store(ctxt, lw, rw, le, re, null_count);
if (rw == 1+lw)
{
/* lw and rw are neighboring words */
/* You can't have a linkage here with null_count > 0 */
if ((le == NULL) && (re == NULL) && (null_count == 0))
{
t->count = hist_one();
}
else
{
t->count = zero;
}
return t->count;
}
/* The left and right connectors are null, but the two words are
* NOT next to each-other. */
if ((le == NULL) && (re == NULL))
{
if (!ctxt->islands_ok && (lw != -1))
{
/* If we don't allow islands (a set of words linked together
* but separate from the rest of the sentence) then the
* null_count of skipping n words is just n. */
if (null_count == (rw-lw-1))
{
t->count = hist_one();
}
else
{
t->count = zero;
}
return t->count;
}
if (null_count == 0)
{
/* There is no solution without nulls in this case. There is
* a slight efficiency hack to separate this null_count==0
* case out, but not necessary for correctness */
t->count = zero;
}
else
{
t->count = zero;
Disjunct * d;
int w = lw + 1;
for (d = ctxt->local_sent[w].d; d != NULL; d = d->next)
{
if (d->left == NULL)
{
hist_accumv(&t->count, d->cost,
do_count(mchxt, ctxt, w, rw, d->right, NULL, null_count-1));
}
}
hist_accumv(&t->count, 0.0,
do_count(mchxt, ctxt, w, rw, NULL, NULL, null_count-1));
}
return t->count;
}
if (le == NULL)
{
start_word = lw+1;
}
else
{
start_word = le->word;
}
if (re == NULL)
{
end_word = rw;
}
else
{
end_word = re->word +1;
}
total = zero;
for (w = start_word; w < end_word; w++)
{
Match_node *m, *m1;
m1 = m = form_match_list(mchxt, w, le, lw, re, rw);
for (; m != NULL; m = m->next)
{
unsigned int lnull_cnt, rnull_cnt;
Disjunct * d = m->d;
/* _p1 avoids a gcc warning about unsafe loop opt */
unsigned int null_count_p1 = null_count + 1;
for (lnull_cnt = 0; lnull_cnt < null_count_p1; lnull_cnt++)
{
bool Lmatch, Rmatch;
bool leftpcount = false;
bool rightpcount = false;
bool pseudototal = false;
rnull_cnt = null_count - lnull_cnt;
/* Now lnull_cnt and rnull_cnt are the costs we're assigning
* to those parts respectively */
/* Now, we determine if (based on table only) we can see that
the current range is not parsable. */
Lmatch = (le != NULL) && (d->left != NULL) &&
do_match(le, d->left, lw, w);
Rmatch = (d->right != NULL) && (re != NULL) &&
do_match(d->right, re, w, rw);
/* First, perform pseudocounting as an optimization. If
* the pseudocount is zero, then we know that the true
* count will be zero, and so skip counting entirely,
* in that case.
*/
if (Lmatch)
{
leftpcount = pseudocount(ctxt, lw, w, le->next, d->left->next, lnull_cnt);
if (!leftpcount && le->multi)
leftpcount =
pseudocount(ctxt, lw, w, le, d->left->next, lnull_cnt);
if (!leftpcount && d->left->multi)
leftpcount =
pseudocount(ctxt, lw, w, le->next, d->left, lnull_cnt);
if (!leftpcount && le->multi && d->left->multi)
leftpcount =
pseudocount(ctxt, lw, w, le, d->left, lnull_cnt);
}
if (Rmatch)
{
rightpcount = pseudocount(ctxt, w, rw, d->right->next, re->next, rnull_cnt);
if (!rightpcount && d->right->multi)
rightpcount =
pseudocount(ctxt, w,rw, d->right, re->next, rnull_cnt);
if (!rightpcount && re->multi)
rightpcount =
pseudocount(ctxt, w, rw, d->right->next, re, rnull_cnt);
if (!rightpcount && d->right->multi && re->multi)
rightpcount =
pseudocount(ctxt, w, rw, d->right, re, rnull_cnt);
}
/* Total number where links are used on both sides */
pseudototal = leftpcount && rightpcount;
if (!pseudototal && leftpcount) {
/* Evaluate using the left match, but not the right. */
pseudototal =
pseudocount(ctxt, w, rw, d->right, re, rnull_cnt);
}
if (!pseudototal && (le == NULL) && rightpcount) {
/* Evaluate using the right match, but not the left. */
pseudototal =
pseudocount(ctxt, lw, w, le, d->left, lnull_cnt);
}
/* If pseudototal is zero (false), that implies that
* we know that the true total is zero. So we don't
* bother counting at all, in that case. */
if (pseudototal)
{
Count_bin leftcount = zero;
Count_bin rightcount = zero;
if (Lmatch) {
leftcount = do_count(mchxt, ctxt, lw, w, le->next, d->left->next, lnull_cnt);
if (le->multi)
hist_accumv(&leftcount, d->cost,
do_count(mchxt, ctxt, lw, w, le, d->left->next, lnull_cnt));
if (d->left->multi)
hist_accumv(&leftcount, d->cost,
do_count(mchxt, ctxt, lw, w, le->next, d->left, lnull_cnt));
if (le->multi && d->left->multi)
hist_accumv(&leftcount, d->cost,
do_count(mchxt, ctxt, lw, w, le, d->left, lnull_cnt));
}
if (Rmatch) {
rightcount = do_count(mchxt, ctxt, w, rw, d->right->next, re->next, rnull_cnt);
if (d->right->multi)
hist_accumv(&rightcount, d->cost,
do_count(mchxt, ctxt, w, rw, d->right,re->next, rnull_cnt));
if (re->multi)
hist_accumv(&rightcount, d->cost,
do_count(mchxt, ctxt, w, rw, d->right->next, re, rnull_cnt));
if (d->right->multi && re->multi)
hist_accumv(&rightcount, d->cost,
do_count(mchxt, ctxt, w, rw, d->right, re, rnull_cnt));
}
/* Total number where links are used on both sides */
hist_muladd(&total, &leftcount, 0.0, &rightcount);
if (0 < hist_total(&leftcount))
{
/* Evaluate using the left match, but not the right */
hist_muladdv(&total, &leftcount, d->cost,
do_count(mchxt, ctxt, w, rw, d->right, re, rnull_cnt));
}
if ((le == NULL) && (0 < hist_total(&rightcount)))
{
/* Evaluate using the right match, but not the left */
hist_muladdv(&total, &rightcount, d->cost,
do_count(mchxt, ctxt, lw, w, le, d->left, lnull_cnt));
}
/* Sigh. Overflows can and do occur, esp for the ANY language. */
if (INT_MAX < hist_total(&total))
{
#ifdef PERFORM_COUNT_HISTOGRAMMING
total.total = INT_MAX;
#else
total = INT_MAX;
#endif /* PERFORM_COUNT_HISTOGRAMMING */
t->count = total;
put_match_list(mchxt, m1);
return total;
}
}
}
}
put_match_list(mchxt, m1);
}
t->count = total;
return total;
}
/**
* classic_parse() -- parse the given sentence.
* Perform parsing, using the original link-grammar parsing algorithm
* given in the original link-grammar papers.
*
* Do the parse with the minimum number of null-links within the range
* specified by opts->min_null_count and opts->max_null_count.
*
* To that end, call do_parse() with an increasing null_count, from
* opts->min_null_count up to (including) opts->max_null_count, until a
* parse is found.
*
* A note about the disjuncts save/restore that is done here:
* To increase the parsing speed, before invoking do_parse(),
* pp_and_power_prune() is invoked to remove connectors which have no
* possibility to connect. It includes a significant optimization when
* null_count==0 that makes a more aggressive removal, but this
* optimization is not appropriate when null_count>0.
*
* So in case this optimization has been done and a complete parse (i.e.
* a parse when null_count==0) is not found, we are left with sentence
* disjuncts which are not appropriate to continue do_parse() tries with
* null_count>0. To solve that, we need to restore the original
* disjuncts of the sentence and call pp_and_power_prune() once again.
*/
void classic_parse(Sentence sent, Parse_Options opts)
{
fast_matcher_t * mchxt = NULL;
count_context_t * ctxt = NULL;
bool pp_and_power_prune_done = false;
Disjunct **disjuncts_copy = NULL;
bool is_null_count_0 = (0 == opts->min_null_count);
int max_null_count = MIN((int)sent->length, opts->max_null_count);
/* Build lists of disjuncts */
prepare_to_parse(sent, opts);
if (resources_exhausted(opts->resources)) return;
if (is_null_count_0 && (0 < max_null_count))
{
/* Save the disjuncts in case we need to parse with null_count>0. */
disjuncts_copy = alloca(sent->length * sizeof(Disjunct *));
for (size_t i = 0; i < sent->length; i++)
disjuncts_copy[i] = disjuncts_dup(sent->word[i].d);
}
for (int nl = opts->min_null_count; nl <= max_null_count; nl++)
{
Count_bin hist;
s64 total;
if (!pp_and_power_prune_done)
{
if (0 != nl)
{
pp_and_power_prune_done = true;
if (is_null_count_0)
opts->min_null_count = 1; /* Don't optimize for null_count==0. */
/* We are parsing now with null_count>0, when previously we
* parsed with null_count==0. Restore the save disjuncts. */
if (NULL != disjuncts_copy)
{
free_sentence_disjuncts(sent);
for (size_t i = 0; i < sent->length; i++)
sent->word[i].d = disjuncts_copy[i];
disjuncts_copy = NULL;
}
}
pp_and_power_prune(sent, opts);
if (is_null_count_0) opts->min_null_count = 0;
if (resources_exhausted(opts->resources)) break;
free_count_context(ctxt, sent);
free_fast_matcher(sent, mchxt);
pack_sentence(sent);
ctxt = alloc_count_context(sent);
mchxt = alloc_fast_matcher(sent);
print_time(opts, "Initialized fast matcher");
}
if (resources_exhausted(opts->resources)) break;
free_linkages(sent);
sent->null_count = nl;
hist = do_parse(sent, mchxt, ctxt, sent->null_count, opts);
total = hist_total(&hist);
lgdebug(D_PARSE, "Info: Total count with %zu null links: %lld\n",
sent->null_count, total);
/* total is 64-bit, num_linkages_found is 32-bit. Clamp */
total = (total > INT_MAX) ? INT_MAX : total;
total = (total < 0) ? INT_MAX : total;
sent->num_linkages_found = (int) total;
print_time(opts, "Counted parses");
extractor_t * pex = extractor_new(sent->length, sent->rand_state);
bool ovfl = setup_linkages(sent, pex, mchxt, ctxt, opts);
process_linkages(sent, pex, ovfl, opts);
free_extractor(pex);
post_process_lkgs(sent, opts);
if (sent->num_valid_linkages > 0) break;
if ((0 == nl) && (0 < max_null_count) && verbosity > 0)
prt_error("No complete linkages found.\n");
/* If we are here, then no valid linkages were found.
* If there was a parse overflow, give up now. */
if (PARSE_NUM_OVERFLOW < total) break;
//if (sent->num_linkages_found > 0 && nl>0) printf("NUM_LINKAGES_FOUND %d\n", sent->num_linkages_found);
}
sort_linkages(sent, opts);
if (NULL != disjuncts_copy)
{
for (size_t i = 0; i < sent->length; i++)
free_disjuncts(disjuncts_copy[i]);
}
free_count_context(ctxt, sent);
free_fast_matcher(sent, mchxt);
}
