Match weak agreement op with the spec.

Previously it would mandate agreement was met on all categories
in a tag with enough categories, if such tag was found.
Now it checks for agreement only on the number of categories that
actually match, including the case of zero categories matching
(the latter does meet the weak agreement).

libwccl/ops/functions/bool/predicates/weakagreement.cpp

@@ -57,13 +57,16 @@ WeakAgreement::BaseRetValPtr WeakAgreement::apply_internal(const FunExecContext&
 	if (t1->lexemes().size() > t2->lexemes().size()) {
 		std::swap(t1, t2);
 	}
-	// check strong agreement between range endpoints
-	// for each possible agreement between them,
+	// Check strong agreement between range endpoints.
+	// For each possible agreement between the endpoints,
 	// check if remaining tokens meet that agreement too,
-	// but take into account only tokens with a tag that
-	// has enough categories, ignoring the rest (hence "weak" 
-	// agreement).
-	// return True if an agreement met by all selected tokens is found
+	// but instead of looking for strong agreement i.e.
+	// matching on exact number of categories, look for
+	// weak agreement i.e. matching only on those categories
+	// that are present.
+	// Specifically, if there is a lexeme that does not
+	// match any of the categories, that means the token
+	// does meet the weak agreement.
 	foreach (const Corpus2::Lexeme& t1_lex, t1->lexemes()) {
 		const Corpus2::Tag& t1_tag = t1_lex.tag();
 		// don't bother checking t2 unless current t1_tag matches enough categories
@@ -72,21 +75,20 @@ WeakAgreement::BaseRetValPtr WeakAgreement::apply_internal(const FunExecContext&
 				Corpus2::Tag inter = t1_tag.get_masked(t2_lex.tag());
 				// if the intersection matches enough categories we have agreement
 				if (attribs->matching_categories(inter) >= min_card) {
-					// check if selected agreement is met by all remaining tokens
-					// but take into account only tokens with a tag that has
-					// proper amount of categories.
+					// Check if selected agreement is met by all remaining tokens
 					bool agreement_met = true;
 					for(int i = abs_left + 1; agreement_met && (i < abs_right); ++i) {
 						foreach(const Corpus2::Lexeme& i_lex, sc.at(i)->lexemes()) {
-							if (attribs->matching_categories(i_lex.tag()) >= min_card) {
-								// token has a tag matching enough categories,
-								// so now it has to meet the selected agreement
-								agreement_met = false;
-								Corpus2::Tag i_inter = i_lex.tag().get_masked(inter);
-								if (attribs->matching_categories(i_inter) >= min_card) {
-									agreement_met = true;
-									break;
-								}
+							// Check if agreement is met, but taking into account
+							// only categories actually matched in current tag,
+							// without requirement to match all categories in the
+							// agreement.
+							Corpus2::Tag i_inter = i_lex.tag().get_masked(inter);
+							agreement_met =
+								(attribs->matching_categories(i_lex.tag())
+								 == attribs->matching_categories(i_inter));
+							if(agreement_met) {
+								break;
 							}
 						}
 					}